This content provides a detailed explanation of rectifiers and inverters, focusing on their principles, types, and applications, particularly within the context of electrical vehicle (EV) systems. It covers the conversion of AC to DC (rectification) and DC to AC (inversion) using various switching techniques and circuit configurations.
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Yeah, good morning to you all. So, I
welcome you all for this today's
session. So, I'm just uh briefing about
like yesterday's session, right? We saw
some fundamentals of electrical and we
saw some fundamentals of electronics and
uh we made a decision to design them
some circuits which is related to
electrical vehicle system. So now we are
uh also was seeing like what is the
importance of power electronics and uh
in power electronics what are the
circuits are available because of
powerronics what can be done in that we
have first chosen for chopper circuit
that converts uh DC to DC right so in
that uh we saw three types that is buck
boost and bug boost and we studied about
the duty cycles and these things right
So today I am just continuing my session
where I left from yesterday right. So
here I'm talk now today we are going to
see about like rectifier.
So yes rectifier is a circuit that
converts AC to DC. So you know in the
fundamentals of electricals we have just
seen like what is the difference between
AC and DC right the major differences
towards the load. The current is the
input supply of AC will have an
alternating current that is current will
flow in both the direction it has two
ars positive off and negative off.
During my positive off it will travel in
one direction and in negative off it
will travel in the opposite direction.
So it has frequency.
uh whereas DC doesn't have change of
current direction. It either goes in a
positive direction or it goes in a
negative direction with respect to the
load. Right? So this is the major
difference between the AC and DC. Now
what we are going to see is that we are
going to build in a circuit. The circuit
is going to operate in such a way that
you are if you give an input in the uh
as a AC and at the output it is going to
get DC. Right? So to build these circuit
also we are not going to implement any
other special uh equipments or these
things. So whatever we learned yesterday
like we know about the switches right.
So basically we are going to arrange the
switches in a circuit and in a manner we
are going to turn it on and turn it off
so that at the output you'll be getting
an DA direct current right. So the most actually
actually
for using rectified. So this is the AC
input and we are going to see this type
of AC sinosidal wave to this type of DC
sinosidal wave. As you see it has two
halves positive and negative.
This is a AC signal and in the X-axis
you can see the time right now this is
the DC signal. same x axis you have time
but you don't have a alternating current
as you have in AC you have a straight
line as DC now what you're going to do
is that your input is going to your
input waveform is going to be in this
way and you are going to convert this
waveform into this way right so this is
what you're going to do for this what
equipment or component what you are
going to use is that you're going to use
diodes right so you can use diodes as
well as transistors also
If you use diode it is called as
uncontrolled rectifier and if you are
going to use thy resisters that is three
terminal devices that is called control
rectifier. As you all know diode is a
device that can turn on but you cannot
turn it off. Whereas thister at whatever
time you need to turn on and turn off
you can do it. That is the difference.
So here I'm going to convert AC signal
to DC signal. So I'm not worried about
the time. So I just ignore the time. So
I don't want at what time it has to on
or what time it has to want to off
because that doesn't depend upon my
output conversion. So for that reason I
can use diode also if you want or I can
use thyister also if I want right. So
basically you know the diode right this
is anode and cathode. So this is going
to be your alternating signal right? So
if I connect this diode in this way. So
whenever my positive off is coming right
this is the positive off. At that time
here I'm connecting a positive input. So
it is in the which case?
It is in which type of bias?
Yes. So it is in forward bias. So if it
is forward bias, what happens to your
diode? It just turn on. So it is turning
on and at the output you are getting
positive. Similarly when it is in
negative right if negative is going to
this point at that point it is going to
be a reverse bias. So I'm just brushing
about yesterday's concept. diode will
turn on when it is forward biased and if
it is reverse biased the current will
never flow and generally we don't do
that right so for turning off a diode we
will just cut off the forward bias so
that it will turn off at its own time
now you are going to get a negative
cycle if negative cycle is coming at
this point it is understood that it is
in reverse bias so at that time you
don't get any output phase right so
similarly it happens for varying cycle
So here from positive and negative off
you have just clipped the negative of
cycles. So at the output you can see
just the positive cycle here in the
output right. So what you have converted
is that at the output you have neglected
all your negative off. So since the
negative off is not there only positive
off is there. This is considered to be a
DC output. Right? But anyhow it is not
replicating this waveform. So for that
we need to do certain things right.
Similarly take this example here the
same signal is given just I have
replaced the diode. So when I am just
replacing the diode when it is for
positive is coming here it is understood
that it is reverse bias. Whereas when
negative is coming here it is understood
ultimately at this terminal could be
positive. So negative off is coming and
triggering at this point. So you are
getting a negative or cycle output. So
diode or one single diode can act as a
rectifier. If you see in the yesterday's
session I have mentioned this the unique
features of diode is it can rectify. So
this is the meaning of rectification.
Rectification means the process of
converting your alternating current to
this direct current. Right? So diode
operates in either way to create a
positive of cycle or a negative of cycle
ignoring the two signals. Okay. So
because of that we can use a single
diode also for your rectification. So
the diode comes in these many
configurations you can see here. So
according to your power requirement or
your uh
heating arrangement and the circuit
arrangement where it is being placed
based upon that you can choose any
configuration of the above mentioned
diode aspects right. So based upon your
thermal characteristics where you're
going to case it you can choose in any
type of any configuration of your diode rectifier.
rectifier.
Now the rectifier broadly it is
classified into two types that is
off-wave rectifier and full wave
rectifier. So off wave rectifier is
nothing but you will be clipping only
one half and you are not you will just
ignore the negative just like you saw in
the example. See here a positive off is
there. This is a input supply I'm giving
here I am using a inductor coil. This is
treated to be a transformer. Okay. But
as for the principle of working, I'm
just taking as an inductor coil. Right?
Inductor coil is there and it is getting
mutually induced to this. This is the
primary coil and this is the secondary
coil. This is being connected to a diode
and this is the load where you are going
to connect your any application. Right?
So this is the way the circuit is going
to be made. Now if you see this is an
inductor coil and you know inductor how
it works. Right? So when inductor is
when the current is flowing through this
way the inductor is getting charged the
current is so here say for example now
it is entering this side this will be
created as a positive and this will be
created as a negative right. So when I
bring any other inductive coil nearer to
this coil the induced current will
naturally induce over this coil. So this
is what I was talking about in the
transformer yesterday right. So based
upon the number of turns see here this
primary side you have more number of
turns and in the secondary side you have
less number of turns when compared to
the primary side. So what you can
understand is that this is going to be a
step down transformer. Right? Now if you
see according to dot theory you have a
theory called dot theory. See here this
is an inductive coil and this is an
inductive coil. Here it is positive and
here it is negative. So when I bring a
inductive coil nearer to this obviously
this will be a positive and this will be
negative this will be a duplication of
this coil. So if this is positive
whenever it is positive off cycle this
will be at positive right. So here it is
inducing as positive and if the current
is flowing through the diode to the
load. Now the diode is forward biased
right when it is forward biased you are
going to get an output
like this. The dotted lines right?
Similarly check for the negative cycle
when it is negative. So this this is
going to be a negative symbol here and
this is going to be a positive symbol
here. So ultimately according to dot
theory this will become a negative and
this will become a positive. So the
negative is coming here the diode is now
reverse biased. Okay since there is
reverse biased the current flow will not
be experienced by the load. So what
happens? The load is not experiencing
any current. So I'm getting a zero over
here and it is leaving back. Now coming
again to the positive again the in the
positive off cycle it will be forward
biased. So it is getting another dotted
lines if you just follow right and again
you'll be getting so you are just
ignoring the negative off. So what
happens is you just all the ignored all
the negative so only at the output you
are getting only positive cycle. So it
is being rectified because negative
cycle is not there. Now since this is
becoming zero I'm not interested in
becoming zero because my ultimate aim is
to bring a waveform like this correct.
So for that what I'm doing I'm just
adding a capacitor. So what is the role
of a capacitor? It's just stores the
energy when the supply is there and when
is when it is then the supply is cut it
just discharges and gives the energy in
the same direction. Right? So when the
diode is forward biased it is getting
the output wtage is coming here. So when
it is reverse biased right this is
storing energy right and when the input
is cut this capacitor will try to
discharge and give the same voltage to
the diode. At that point this will come
like this and not become zero unless and
until it is becoming zero it is coming
here and it is coming here. Right? So
this is called as a filter circuit
because it is filtering the zero
crossing of this waveform. Right? So
this is the role of a capacitor.
Okay. So this is how the half rectifier
is working. Just if you know the
principle of each and every component
and the network theory like how the
current is flowing in one direction and
leaving in another direction, you can
easily understand the concept of any
circuit. I hope so this circuit is very
clear for you. Am I correct?
So just
if I want to make this as a three-phase
configuration then what I have to do
right? So here if you see this is a
three-phase RA rectifier. So you have
three phases VA, VB and VC and you have a
a
neutral supply. Okay. Now you are having
a waveform here. This three waveforms
will have a phase shift of 120°. That is
this is starting here and from here from
this 0 point to this 0 point you have a
phase shift of 120° and from Y to B you
have a phase shift of 120°. So you all
the diodes are connected here and all
the output is connected to one
particular terminal that is one node and
the load is connected to here. Okay.
Right. Now if your waveform is coming in
the positive off obviously this diode
will get forward biased. So you are
getting a forward biased waveform like
this. So in the negative off before it
is getting into the negative off what I
will do because I'm having a 120°ree
phase shift in the next using the next
diode immediately I'm getting the next
uh waveform as positive. So without the
role of capacitor here I'm able to get
the output waveform like this. Okay, it
is actually a three-phase waveform. In
this three-phase waveform, I'm getting
an rectified output at this point.
Right? Okay. So now I hope so this is
clearly understandable for you. So the
concept is very simple. You are just
connecting a diode. The diode is will
work when it is forward biased. When I
can consider my diode is in forward bias
means so when my anode is actually
connected to the positive terminal. So
my input is I'm through my input I'm
giving alternating current. So
alternating current will provide
positive also as well as negative also.
So whenever it is providing a positive
the diode is switching on. Whenever it
is providing a negative off cycle the
obviously the diode is reverse bias. So
it will not allow the current to flow
through it. So the load is experiencing
the current in only one direction and
not the other way. So according to the
load it is acting as a DC only. So only
current flow we are just changing it. So
from this what you can understand is
that I am not doing anything with
respect to the input. My output is load.
The only concept is the load is a DC
load. Okay. The load is a DC load. The
load want only DC supply means what the
load will under how I'm making the load
to work is I'm not giving a DC supply.
Instead I'm giving an AC supply. Now the
load has to work only in the DC supply.
So the uh the load is uh trained in such
a way that you imagine this way the load
is trained in such a way that if the
current is coming in only one direction
I should work. So what I'm doing is
input is having current direction in
both the direction through my switching
operation. I'm just making the load to
believe that the current is coming in
only one direction. Okay. So the load
doesn't know what type of input is
coming to it but the current flow is in
the same direction. So it is accepting
that it is a DC. So in this way only we
are going to make a AC to DC conversion
or DC to AC conversion. We are not going
to change anything in the input side.
Instead we are making the load to
believe that the current is coming in
one direction or the both the way
direction by which we can convert AC to
Yeah. So now the next type is the center
tapped full wave rectifier. Right. So
see here this is another type of
arrangement. Here if you see again I'm
going to play with this dot theory and
the inductive coil only. See here.
So this is my input. My input is having
an AC inductive coil. This this point
and in the secondary side I'm having
another inductive coil. Right? So in
this middle I'm just connecting my load.
This is my load. RL is my load. Okay? So
from there I'm just connecting it in
this way. I'm having two diodes. Okay.
So see here this is A C B three points.
Now as I said in the dot theory, right?
when it is connected in bringing your
inductive coil in this way. What happens is
is
if this is positive and this is negative
the secondary coil also will experience
this is positive and this is negative.
But if I keep the same coil down here as
a series as you see here. Okay. Now if
this is positive this this point will
become negative and again this will
become positive and this will become
negative. It will be in this in this aspect.
aspect.
Are you understanding? So if A is
positive, C will see C the upper part of
C will be negative and lower part of C
will be positive and B will be
ultimately negative. So it will be in
this aspect. Now you just take a minute
minute time so that you can understand
like how the waveform is coming in
positive and in negative when when it is
experiencing you have to think about one
thing how the current will travel is
from positive to negative through the
load. So this is your load. Okay. So
from positive to negative the current
will flow through the load. So when this
is positive and this is negative, this
will be positive and this will be
negative. But in the C you can see upper
part will be negative and lower part
will be positive. Okay. So this is
called as dot theory of the inductance.
So you just go through the circuit and
understand this waveform. I'll give a
So were you able to understand how it is
So the positive will off will come here.
When positive off is coming this will
become positive. This will become
negative. So at the same time this will
become positive and this will become
negative and this will become positive
and this will become negative. So
wherever it is getting positive at that
diode only it will get forward biased.
When it is forward biased it will come
here through the load. It is again going
here and again it will come here. So it
will come here. Again it will reach the
diode. So it will be like a loop.
Okay. So you'll be continuously getting
the output DC waveform like this. It
will you will not even in the negative
cycle it is quite similar to your
three-phase only. But what is the
difference between your three-phase and
this is here you can see the magnitude
your magnitude will be much more higher
when compared to the three-phase of this
magnitude. So this is the difference
between it. Right? So this is how this
thing is happening in a center taped
full wave rectifier. Now I'm just going
to reconfigure
this uh same thing the same thing into a
bridge form of circuit. See here this is
called the bridge arrangement. Okay. So
now I'm just increasing the more number
of switches D1 D2 D3 D4. Just understand
the concept. Okay. See here I'm just
explaining the circuit first. So this is
the input. You are making an arrangement
like this. D1 D2 D3 D4 like this in this
arrangement and now your input of AC
supply is connected to one point neutral
to be this point and face to be at this
point okay where I am taking output is
in between D2 and D3 this point this
point actually you can draw this redraw
the circuit like this also just for your
uh understanding purpose I'm giving like
this and later on I will explain you see
here this is A load right here. Here it
is load. This load can be connected here
also. Since it is it will create some
clumsiness. I have created the circuit
in this way. Like load is connected
here. Okay. You know the role of this
capacitor. This capacitor is used as a
filter. So that your positive of voltage
is not going to zero. So it will be like
a smoothing waveform. Right now. So it
is called as a smoothing capacitor. See
here. So just follow the circuit. When
positive off is there which two diodes
will switch on and when negative off is
there which two switch on will switch
on? You just comment in the chat box
take few time.
So just imagine you cannot if if you are
able to draw it in a note and check just
make this load to be across this point
this positive and negative since it will
create clumsiness I have
drawn in this way. So if you want to
analyze keep this load in between this
positive and negative here.
If you keep like this that will be more
I'll just give a couple of minute time
you just uh understand it. So when I am
explaining again you will understand you
will you can correct yourself like what
where you are going wrong. That will
help you to understand much more easier
answers are coming.
Just what about others? You may also try it.
it.
Though you are non-elect electrical, you
can just follow the things what you I am
telling and you can try it out
so that it will be easy for you to
understand. Just try it out.
If you are qu asking why we are not
getting from initial 0 volt, you'll be
getting from initial 0 volt only. Uh you
that you need to understand through
delay. Okay. So hopefully if uh the
theoretical is being ending like uh
through inverter today in today's
morning session in offline session
you'll start with the demo right at that
time you can understand that delay what
it is and uh zero how you can make it to
actually it is starting from zero only
just for your
just for For understanding we are doing
that that can be easily understood
So I'm getting few answers. Okay. So now
I'm just continuing with my session
here. See here the same circuit I am
just giving you. This is the this is for
your positive off. Okay. So for your
positive off you the current is going to
come here. This is a node right? When
this is the node the current will try to
divide correct the current is dividing.
This is at reverse bias. So this will
this will not work. Now the current will
come here. That this diode is forward
biased. Okay. So this is forward biased.
So this will work. The current will go
here. Again at this point this current
will try to divide. So it is dividing in
this way. You see D4 is reverse biased.
So again it will not work. So through
the load it is going here. Now maybe the
load you can consider as bulb. So the
bulb is glowing now. Now it is coming
current is coming at this point. Now
your D3 is actually forward biased. So
when it is forward biased it is coming
here. It is going there and the circuit
is closed. Right? Similarly in the
negative off if you see so you got a
positive off like this right. Similarly
in the negative off this is your output.
Negative off if you see the negative off
is coming here. Okay. See in the below
below circuit the negative of it is
coming here. Right? So this is becoming
a positive and this is becoming a
negative. Now at the input terminal now
it is coming here. The current is coming
at this point. The current is trying to
divide. when it is divided again this is
reverse biased at this stage. So my
forward biased is D4. Now the D4 is
forward biased. Right? Now it is coming
here. Again at this node the current is
trying to divide. When it is going
towards D1 it is reverse bias. The
current will not flow here. So the
current is coming here. The bulb is
blowing. Now it is coming here. It is
attaining at C. Now again the current
will try to divide. So the current is
trying to divide. Now it is going in
this way. D2 is bordered by us and this
is coming in this way and it is ending
in this way. So during my positive off
my D1 and D3 is on. During my negative
off D2 and D4 is on. So over has given
this answer they are right and I and I
am happy like most of you have given a
right answer. So I think you understood
the concept very easily. Right? So I
think now you are in now you know the
cir how to build your circuit with these
things. Now
I'm just going to type of rectifiers.
Okay. So what are what are the types the
rectifiers are available. So if you take
in a EV generally why we are using
rectifier is we are going to convert the
AC to DC. In EV we use this rectifier at
the point of charging. Okay. So from
your grid, from your uh transmission
line, from your grid, you are just going
to connect it to a connector, right? Or
your socket, okay? From socket, you are
just through connector, you are going to
change that AC input power to DC output
power. Then only your battery is going
to get charged. So this rectification
process generally happens at which point
it will be happening at your
plug point or socket that is the three
holes which where you find no at that
point or at the connector. So generally
we make it at the connector point and it
will convert into DC and then it will
give it to the battery again. So this is
what it will be happening generally we
will make in that way only. So it will
convert the DC and it will give it to
the battery. So we will not actually
convert directly into DC and we will
give it if you connect uh convert
directly into DC and if you are charging
the battery through the socket and the
DC itself it is faster called as fast
charge. Okay. So anyway your source is
in input is you are available AC sources
only. So anyhow I need to convert that
into a DC to use for my battery
charging. Right? So in this way if you
see in more configurations you have the
rectifiers are being classified based
upon the faces that is a b c you saw
know generally we will notate it as r y
b in electricity right now if you see here
here
in singlephase you have only phase and
neutral. Okay whereas in three-phase
what do you have? You have r y three
phases and one neutral. Correct. So in
singlephase rectifier you have again
three types. Uncontrolled, offcont
controlled and fully controlled. Okay.
So uncontrolled means you know that we
are going to use diode at the switch.
Controlled means you know that you are
going to use transistors as your
switches. So in the same way three-phase
also you'll be having uncontrolled, half
controlled and fully controlled.
Generally in in use we will be using
either an uncontrolled or fully
controlled. We will not be using half
control. Right? So these are the
configurations in which the rectifiers
are available. So in the rectifiers
uh in all the configurations you have
another two subcategories that is half
wave and full wave. So what is the
meaning of halfwave and full wave? So
only if one half is being converted as a
to an output then it is half wave. If
both the cycles positive off and
negative off. If both the cycles are
being converted to one pulsating signal
then that is called as full wave
rectifier. So these are the different
types of rectifier. Now so now we are
coming into three-phase full wave full
wave bridge rectifier. Okay. So this is
the bridge circuit. So you need to
understand this concept very clearly.
Okay. Now you are going to use D1 D. So
this is the numbering order. See here
D1, D4, D3, D5, D2, D4, D6. Okay. So in
this order only you should actually
number your diodes. And this how it is
numbered means see after D1 D2 will be
on it and D3 will be on and D4 will
switch on. D5 D6 in this order you have
to go. So that is the thing. So as of
now I'm just leaving the input and
output and just explaining this bridge
circuit alone. Okay. So in this bridge
circuit if you take you have totally six
number of switches. Why six number means
three phases. So for for per phase you
need to use minimum two switches. So in
this aspect if you see for the three
phase you are having totally six number
of switches 1 2 3 4 5 6. So totally six
number of switches you are having. So if
you see the conduction of these switches
it will be in this order. D1 D2 D3 D4 D5
D6 right now how you are what is the
thumb rules of this bridge circuit.
Okay. So this is generally we will call
this one leg, two leg, three leg. Okay.
Totally three legs you are having. So in
maybe in a technical language you may
take it as branch one, branch two,
branch three. In branch one two diodes.
In branch two, two diodes. In branch
three, two diodes. D1 and D2 are in
branch one. D3 and D4 are in branch 2.
D5 and D6 are in branch three. Now these
are three branches. Now if you see I'm
taking it in row, upper row and bottom
row. So this one, D1, D3, D5 are in
upper row and D2, D4, D6 are in lower
row. Okay. So how the the upper rows
whenever you are getting a positive off
cycle the any switch from the upper row
will be switched on. Okay. Whenever you
are getting negative off cycle negative
of cycle this is you take this thing
this is positive of cycle and this is
negative of cycle. So whenever positive
of cycle is coming any one switch from
the upper arm will switch on. Okay. So
whenever negative off is coming any
switch from the lower arm will be
switching off. So this is the rule.
These are the rules. Another most
important thumb rule is that you have to
make a you have to make a switching
arrangement in such a way that D1 if D1
is on in the same branch D2 should not
be on. Is that clear? So if this switch
is on either D4 or D6 should switch on.
If D3 is on, D4 should not be on. Either
D2 or D6 should switch on. If D5 is on,
D2 and D4 should not should only switch
on, not D6. So the thumb rule is in one
branch in one branch only one switch
should switch on. Is that clear? So why
I should not switch on the two switches
in a single branch? If I do that, what happens?
In one in one branch if both the
short circuit correct so if in one one
branch both the switches are on it will
become a short circuit. So I need to
switch on one circuit from here and one
switch from this branch or this branch.
So this is what I need to maintain. So
by making a switching arrangement you
will convert this sort of waveform into
this. Okay. So now how it is being
converted. Okay. So that is what we are
going to see now. So I'm just showing
here. See here. So this is a small write
up which was made by myself. So see here
this is called as phaser diagram. So
this is three-phase VR, Vy and VB. So
three phases will have a phase shift of
120°. This is called as phase voltage.
In a three-phase
uh circuit in a three-phase transmission
system you have totally three phase
voltages. Okay. So you will also be
having what now? You will be also be
having line wtages. So what is the
meaning of line wtages? The voltage
between two lines. Okay, we have three
lines, right? So V R Y the voltage
between R and Y is called as line
wtages. V R Y.
Okay. So you can do a ve if you if you
apply the algebraic equation here v y is
equal to if you change this into a
vector addition concept. So v r minus
vy. So vr minus vy can be written as vr
+ minus vy. Correct? So this is how we
can write. So if I represent the same
vector di this phaser diagram like this
okay into a vector diagram what happens
is so you have VB vy and vr all the
three is having 120° phase shift among
each faces now for opposite to vy you
have minus vy similarly opposite to vb
you have minus vb opposite to vr you
have minus vr right if If you are
closing if you are doing a vector
addition between these two then only
you'll be getting V R Y correct. So the
vector addition with these two is you
just draw a line here and this will give
you the summation of this largest and
lines will give the summation of this is
actually this is not actually repaired
for you just for understanding I'm just
telling. So if you see the angle between
these two between this 120° minus VR and
minus 20 is 60° and the angle between VY
and VR is 30° right. So this is what you
need to understand for switching angles.
Now totally how many how much amount of
how many line wtages will be there means
here here I'm representing V R Y V YB
and VBR and another three line wtages
will be there which is in reverse
direction of this V Y R V and V RB. So
totally you have three phase wtages and
six line wtages.
The phase angle between the line wtages
how you will be getting is that 360° one
sinosidal waveform one complete
sinosidal waveform is 360°. So 360°
divided by six line wtages you'll be
getting 60°. So why we should get this
means see here in the in this phaser
diagram you can understand. So each
switch will for a line voltage it will
conduct for 60°. Okay, why I need to
find this means I need to switch on for
how much time that I need to understand.
So for that only I understood like so
I'm going to have a 60° of conduction
period of for each switch. Okay, see
here I'm just putting the same thing
into a switching diagram now. Okay, 0 to
60. Okay. 60 to 120, 120 to 180, 180 to
240, 240 to 360, 360 to 3, 360. Okay.
Now in the from the diagram we
understood like each switch will be
conducting for 60° correct and from each
phase you have a phase shift of 120°. So
what I can understand is this from the
upper switch. Okay. In the upper switch
I am I if I am conducting okay if I am
conducting how I have to conduct is that
I need to conduct it for 60° the next
switch will be switching on after 120°
phase shift only. So in this aspect if
you see the switch one T_1 and T2 T1
will conduct for 60° but my T3 will
conduct I'm taking only for upper switch
now T3 will conduct in 120° see till
120° my T on will be on T1
right after that T3 will be on for
another 120° and again T5 will be on for
another 120°
Now my T2 my T2 I need to switch on. So
my two now I need to switch on my lower
switches. So if I want to switch my
lower switches how I can understand is
T1 will be conducting for 60°. From
there I'm just making a shift over
there. So my 22 is conducting from 60°.
So 60° it will conduct till 120°. So
till 120° I'm making the T2 to conduct.
After that T4 it is starting. T4 is
switching on and after that for after
120° conduction of T4 T6 is switching
on. So T6 is coming here.
So if you just check with that
three-phase waveform I'm just making as
a table column. Now see here angle
firing sequence and phase voltages.
Right? So 0 to 60, 60 to 120, 120 to
180, 180 to 240, 240 to 300, 300 to 360.
So 0 to 60, what two switches are on? T1
and T6. Okay. So I'm writing this T1 and T6.
T6.
Next for 60 to 120, T1 and TS2. So T1
and T2. So I'm just filling this table
like this. So from 120 to 180, 120 to
180, T3 and T2. So T3 and T2 180 to 240
T3 and T4 180 to 240 T3 and T4 240 to
300 T5 and T4 240 to 300 T5 to T4 300 to
360 T5 and T6. So T5 and T6. Okay. Now
you just apply this to the circuit. Okay.
Okay.
Just you draw this circuit and keep in
keep in your mind. Okay. T1, T2, T3, T4,
T5, T6. Okay. Now you keep this if you
have a rough note or any paper you just
draw the circuit and you just keep it uh
aside of that so that you'll be
understanding much more better. Right?
So now
when T1 and T6 is on T1 and T6 T1 is
responsible for VR. Okay. and T6 is
responsible for Yphase. So you will be
getting a phase wtage of V R Y.
When T1 is on, T1 will responsible for
VR and TS2 is on the leg of the branch
of B. Right? So B is switched on. So the
voltage phase wtages V RB. So when T3
and TS2 is there in the branch V and VB
will be there. So similarly if you
follow the switching pattern these phase
voltages will be there. So once you
complete this
you just apply it in a graph like this.
So 0 to 60 0 to 60 you take as 1 to 60
60 like this. Drawing this graph you'll
be understanding this. So you just draw
a waveform like this and you can add an
output for each and every here you can
see for each and every 60° you'll be
getting this sort of output as an output
waveform. So what you made your input
was sinosidal
you see just at an output you have just
converted into a pulsating DC so if I
don't want this drop over this point I
just needed to add a capacitor at the
end. So if I add a capacitor this will
not become zero. Instead it will become
a straight line like this. So that is
DC conversion. Right? Have you
understood the concept? So what you can
do is that if you want you can I'll just
give some five minutes of time. You can
just go through this switching pattern.
You may just practice it. Okay. Five
minutes of time I'll give and just uh if
you you may drop your uh queries in the
live chat box.
In each cycle I'm getting a question
like in each cycle the more positive and
more negative faces will content right.
So if you have any doubt over here
because this is very easy way to
understand. If you if you understood
this then you understood the entire
I'll just give now the time is nearly
10:55 till 11 I can just give some time
let me just go through this if you have
time you just practice over paper so
that you will be understanding much more clearly
clearly
so again I will repeat it. So maybe I'll
give some 3 minutes of time you just try
to understand by yourself. Uh again I
I'm there to explain it because the same
concept we will see in a reverse way for
inverters. So ho the same concept you
are again and again we we are going to
go through it no problem but you just uh
try to understand by yourself for 3
minutes you just take a 3 minutes of time
time
and uh by then again I will once again I
will repeat it so that you will
Yeah. Okay. So I think uh again I will
take few minutes to explain it. So I'm
just explaining it. uh
what you can do is that uh maybe see
this requires actually board teaching if
it is board teaching then it'll be much
more easier but anyhow in during your
afternoon demo session you'll understand
much more clearly than this I hope so
anyhow I'm just taking few minutes of
time to explain this so this is a bridge
circuit right so you are having totally
switches so you are having a three-phase
conversion of uh AC here. So I'm for
each phase I'm using two switches,
right? So totally six number of
switches. So VA that is R phase you are
connecting red face you are connecting
here and B phase is not connected here
and it is connected here. Cph face it is
not connected here. It is not connected
here and it is connected here. Right?
And your output as this point because
you're connecting all the diodes in the
single point and you're connecting it to
the positive terminal of your load and
all negatives are connected to the lower
switch and the negative connected to the
negative part of your right this is the
circuit arrangement. So
as you all know as the AC waveform is
coming whenever the positive terminal is
coming when the positive terminal hits
that particular diode at the anode point
that anode point diode will switch on by
it automatically right so this is what
I'm going to do so we are going to make
it switch it off automatically when
you're using the diode but the same
circuit when you are using tyristers or
any type of IGBTs the transistor will be
switching on when you give the switch
supply right when you give the gate
triggering point that time only that u
switches will switch on. Similarly if
you stop the gray triggering point the
time will switch off uh switch off and
switch on. Now I am taking this example
if you follow like this
how the whenever the positive is coming
at that point you consider this to be
positive and this point to be negative.
Similarly, whenever the negative of
cycle is coming, you consider this point
to be negative and this point to be a
positive. And I explained the circuit
correct. This is also the same way only
instead of four switches here, we are
going to use six switches. Okay. So
whenever positive off is coming right,
this diode D1 will switch on. Okay. So
when the diode D on is switching on and
ultimately at that point another D6 will
be in negative off. See here if the
circuit is coming here. Okay. So it is
coming here and it is going here this
way and it will come here this way. So
this is how the circuit if D1 and D6 is
switch on. So now for better
understanding what we are doing is we
are not leaving the concept of automatic
switch on and switch off that you can
learn by yourself like whenever you can
just follow as as we taught in the uh
this half rectifier right. So now what
I'm doing is I'm just connecting this
switches to be a controllable switch and
I am going to switch on by myself. So if
you see here if I want to switch on what
I have to do okay so for that only I
should find what is the conduction
period. So how I'm going to conduction
how I can find the conduction period
what is the angle I can how I can find
is by means of this phaser diagrams. I
know there are three phases VR VY and
VB. All the three are
okay. All the three are differentiated
by itself as a phase shift of 120°. So
here you can see it. Now in a
three-phase we do have line wtages. Line
wtages means what? The voltage between
two lines because here you are
considering the voltage to be between
two lines only because two switches has
to be switched on from each branches.
That means what? Two lines. The branches
you consider as line. So two lines has
to be switched on. So what is the line
voltage means? VR, VY, VB. These are the
line wtages. If you see six line wtages
will be there. V R Y, V Y B, VBR.
Similarly, Vy R, VB Y and V RB. Right?
So if I take the six line voltages, the total
total
uh singlephase waveforms conduction
angle is 360°. So if I divide it by six,
six line voltages, I get 60 60°. So for
each 60° each uh line wtages should be
conducting that is VR will be conducting
for 60°. Okay. And each phase will have
a phase shift of 120°. That means what
in this column two switches will be
operating for 60. In this row if you
take each switch will be operating for
120. So you have to consider this way.
See these are faces right? So each faces
will conduct for 120.
T1 is connecting for 120. T3 is
conducting for another 120. T5 is
conducting for another
120. Similarly, if you take the lower,
T2 is conducting for 120. T4 is
conducting for 120. T6 is conducting for
another 120. So, if you take the line
wtages, it is in column. Okay. Line
wtage is in column. So, it will be
conducting for 60. See here T1 T6 is one
combination that will conduct for 60.
Check with other combination. T1 TS2
that will be happening for another 60 T3
TS2 another switches. So this is I am
switching on for this particular time to
achieve a correct waveform. Okay. Now
the angle is 0 to 60. So the 0 to 60 60
to 120 I'm just putting this angles in
column wise mode. Okay. So 0 to 60, 60
to 120, 120 to 180, 180 to 240, 240 to
300, 300 to 360. Right? I'm just for
each period I'm seeing which are the
switches switching on and switching off.
So T1 and T6 is on during 0 to 60. So T1
and T60 T6. Similarly in during 60 to
120 T1 and TS2 is switching on T1 and
T2. Similarly from 120 to 180 T3 and T2
from 180 to 240 T3 and T4. 240 to 300 T5
and T4. 300 to 360 T5 and T6. So I have
written here. So when I switch on this
switch, okay, when I switch on the
switch, what wtage I get at that output?
That is what I'm trying to fill in this
this column. Okay. So see here first one
is T1 T6. So when T1 and T6 is there, T1
is Rphase and T6 is connected where? To
the C phase. So this is what I have
written here. So
T1 and T6 next
next
T_1 and TS2
T_1 and T2. So like this if you follow
you'll be getting different types of
phase wtages.
See here if you take the waveform like
this and if you see here you'll be
getting VR at the output you'll be
getting zero VR
VRB VYB VR VBR and VB. So like this
you'll be getting at that output
terminal. So this is what your circuit
is all about. So this is how you are
going to rectify your input three-phase
input to the three-phase DC output.
Right? So this is what about rectifier.
Now I think you may understand is that clear?
Yeah. Afternoon session we'll be trying
So next we are going to see about the
inverter. Okay. So what is an inverter?
Okay. The inverter converts DC voltage
to AC voltage. Okay, in most of the
cases the input DC vol wtage is lower
while the AC is equal to the grid supply
of voltage. So generally when you are
converting AC to DC your AC will be
higher and that output you'll be getting
DC know that value will be much lower
than your AC input. Okay? Right? So if
you see the types of inverter so
according to the type of your waveform
you will be getting square wave inverter
and modified sine wave inverter. So
generally if you see what as we all know
you are having a DC supply means you'll
be having a straight output whereas in
an AC you'll be having sinosidal output
that sinosidal output should have
positive off and negative off. Okay. So
again I'm telling you you just imagine
like your DC is a straight line that I
have to convert into this sort of
sinosidal waveform right. So it should
have a positive off and it should have a
negative off. Okay. If it is going to
have a positive off and negative off
then only to my load I will get the
current in both the direction. In
positive off you can go higher uh sorry
in positive off it will go in one
direction and in negative off it will
come in the other direction. So this is
how this circuit will happen. Right? So
now actually the cinosidal waveform is
coming here. Right? And then it is
coming here and this is going there as a
cinosidal waveform. I have to convert
this type of waveform only. So if it is
a pulsating you can see it is in
pulsating. So actually I should get this
type of sinosidal waveform. For that you
need to use certain techniques so that
you'll be getting modified sine wave
inverter. So according to the waveform
if you see you have two types square
wave inverter and modified sine wave
inverter. Okay. So what is actually a
challenge in inverter. Okay. You don't
have challenge in anything in rectifier.
Why? Because in rectifier in rectifier
if you see uh you are going to convert a
AC to DC correct you are going to convert a AC to DC so AC has particular
convert a AC to DC so AC has particular time interval whereas DC doesn't have so
time interval whereas DC doesn't have so you can you need not worry about the
you can you need not worry about the switching time okay for example we have
switching time okay for example we have calced a switching time of 60° 0 to 60°
calced a switching time of 60° 0 to 60° these switches will be on these switches
these switches will be on these switches will be off right but if that is not
will be off right but if that is not correct also if you're moving it for
correct also if you're moving it for conduction period more time also then
conduction period more time also then also at that output you will not be
also at that output you will not be having any difference because your DC is
having any difference because your DC is not at all depending upon time okay
not at all depending upon time okay whereas when you're converting DC to AC
whereas when you're converting DC to AC okay this should be of equal interval
okay this should be of equal interval this is one particular sign see here
this is one particular sign see here this is one particular cycle right your
this is one particular cycle right your positive off and this negative off
positive off and this negative off should be equally so this time period
should be equally so this time period for this positive off and this time
for this positive off and this time period for this negative off should be
period for this negative off should be equal. Okay. Then only you'll be getting
equal. Okay. Then only you'll be getting a frequency of 50 Hz or 60 Hz according
a frequency of 50 Hz or 60 Hz according to your need. So frequency is nothing
to your need. So frequency is nothing but 1 divided by this t. So if you want
but 1 divided by this t. So if you want 50 Hz, what would be the time period?
50 Hz, what would be the time period? Frequency is 1 by t. If your frequency
Frequency is 1 by t. If your frequency is 50 Hz, what is the time period? Just
is 50 Hz, what is the time period? Just comment in your chart chat boxes.
Again I'm repeating frequency is equal to 1 by time period. So if I want to get
to 1 by time period. So if I want to get 50 Hz, what is the time period of the
50 Hz, what is the time period of the cycle?
0.02 Everybody is giving correct answer. But what unit?
Correct. 0.02 seconds. Okay. So 0.02 seconds means
seconds. Okay. So 0.02 seconds means what? This positive off should be 0.01
what? This positive off should be 0.01 and this negative off should be 0.01.
and this negative off should be 0.01. And totally this cycle is 0.02 seconds.
And totally this cycle is 0.02 seconds. So in 0.01 second you have to make it as
So in 0.01 second you have to make it as positive off and 0.01 01 seconds you
positive off and 0.01 01 seconds you have to make it as sec negative negative
have to make it as sec negative negative of then only you'll be getting a 50 Hz
of then only you'll be getting a 50 Hz of sinosidal waveform. So in converting
of sinosidal waveform. So in converting DC to AC it is very important to turn on
DC to AC it is very important to turn on the switch and turn off the switch at
the switch and turn off the switch at the right time. So the switches which
the right time. So the switches which you are going to keep right the switches
you are going to keep right the switches which you are going to keep right it
which you are going to keep right it should turn on and turn off at your
should turn on and turn off at your distinct time your designated time. So
distinct time your designated time. So can I use diode as a switch for
can I use diode as a switch for inverter? My next question,
inverter? My next question, can I use diode as a switch for making
can I use diode as a switch for making inverter circuits like this inverter
inverter circuits like this inverter circuit?
Correct. So there there I got an answer like as they are uncontrolled they
like as they are uncontrolled they cannot be used. Correct. Since diode
cannot be used. Correct. Since diode cannot turn off at at our time instant.
cannot turn off at at our time instant. Diode cannot be used to construct as a
Diode cannot be used to construct as a inverter circuit. So there is no concept
inverter circuit. So there is no concept called uncontrolled inverter. As you
called uncontrolled inverter. As you have in rectifier you have only
have in rectifier you have only controlled switches. So controlled
controlled switches. So controlled switches should only be used. So
switches should only be used. So controlled inverters are only there.
controlled inverters are only there. There is no concept of uncontrolled
There is no concept of uncontrolled inverters. So one type of inverters we
inverters. So one type of inverters we saw. The next type is according to the
saw. The next type is according to the type of load what type of load you are
type of load what type of load you are connecting whether it is a singlephase
connecting whether it is a singlephase load or you are going to use a
load or you are going to use a three-phase load. Accordingly you have
three-phase load. Accordingly you have singlephase inverter and three-phase
singlephase inverter and three-phase inverter. In singlephase inverter you
inverter. In singlephase inverter you have halfbridgeidge inverter and
have halfbridgeidge inverter and fullbridgeidge inverter. Similarly in
fullbridgeidge inverter. Similarly in three-phase according to the conduction
three-phase according to the conduction mode you have 120° mode and 180° mode.
mode you have 120° mode and 180° mode. Generally we will be using three-phase
Generally we will be using three-phase inverter 180° mode of operation. So is
inverter 180° mode of operation. So is that clear? So I think you are giving a
that clear? So I think you are giving a good answers and right answers in the
good answers and right answers in the chat boxes. I'm very happy. Right. So
chat boxes. I'm very happy. Right. So I'm just for going with the flow here.
I'm just for going with the flow here. If you see the inverter generally the
If you see the inverter generally the inverters are classified into two types.
inverters are classified into two types. Okay. Wage source inverter and current
Okay. Wage source inverter and current source inverter. In short voltage source
source inverter. In short voltage source inverters are called as VSI and current
inverters are called as VSI and current source inverters are called as CSI.
source inverters are called as CSI. Right? So the power circuit of VSI is
Right? So the power circuit of VSI is like this. So you have a voltage source
like this. So you have a voltage source here. Correct? Input wtage is kept
here. Correct? Input wtage is kept constant.
constant. Okay, that is the main concept of your
Okay, that is the main concept of your voltage source inverter and you are
voltage source inverter and you are going to control the current toward in
going to control the current toward in this circuit. You are going to keep this
this circuit. You are going to keep this voltage constant and you're going to
voltage constant and you're going to control the current flowing through it.
control the current flowing through it. Right?
Right? Similarly, if you see current source,
Similarly, if you see current source, you just you have a input current is
you just you have a input current is kept actually the constant by means of
kept actually the constant by means of an inductor here. Okay, you are keeping
an inductor here. Okay, you are keeping the current as a constant over here and
the current as a constant over here and you are going to control through
you are going to control through voltages. Okay, so this is the concept
voltages. Okay, so this is the concept of your two types of inverters. So
of your two types of inverters. So generally we will be using voltage
generally we will be using voltage source inverter. This current source
source inverter. This current source inverters are used for any specific
inverters are used for any specific application. Okay.
application. Okay. So this is the difference between a
So this is the difference between a voltage source inverter and a current
voltage source inverter and a current source inverter. In voltage source
source inverter. In voltage source inverter the input wtage is kept
inverter the input wtage is kept constant. Whereas in current source
constant. Whereas in current source inverter the input current is kept
inverter the input current is kept constant. What here it is fed from a DC
constant. What here it is fed from a DC voltage source having small or
voltage source having small or negligible impedance. Whereas here you
negligible impedance. Whereas here you your CSI you have a adjustable current
your CSI you have a adjustable current source from a DC voltage source of high
source from a DC voltage source of high impedance. Okay. So here actually you
impedance. Okay. So here actually you can just go through it. This is actually
can just go through it. This is actually small differentiation. This I have given
small differentiation. This I have given for a theoretical question. This may not
for a theoretical question. This may not be that much helpful for you but where I
be that much helpful for you but where I can just
can just um
um tell is that yeah here here actually see
tell is that yeah here here actually see here the last part that is pulse with
here the last part that is pulse with modulation technique is used and pulse
modulation technique is used and pulse with technique is not used in a current
with technique is not used in a current source inverter. Okay. So generally we
source inverter. Okay. So generally we are we will not be using this current
are we will not be using this current source inverter. We'll be using voltage
source inverter. We'll be using voltage source inverse for electrical vehicle
source inverse for electrical vehicle application here. So here uh we use
application here. So here uh we use pulse with modulation techniques to
pulse with modulation techniques to switch on the switches. So that also
switch on the switches. So that also I'll be telling in this uh end of this
I'll be telling in this uh end of this session.
session. So see here now now
actually this is the circuit. Okay. So generally I uh
generally I uh so generally I make the my peoples to
so generally I make the my peoples to learn in this way like you have to learn
learn in this way like you have to learn it properly. So I just made this type of
it properly. So I just made this type of uh
uh practice session. See here. Now here we
practice session. See here. Now here we are going to now study about the
are going to now study about the switching sequence of this. So here you
switching sequence of this. So here you can understand T1. See you you can just
can understand T1. See you you can just ignore this diode. Okay. Diode is used
ignore this diode. Okay. Diode is used for uh this thing only like uh
for uh this thing only like uh protection devices only. So whenever
protection devices only. So whenever high current is flowing it will just uh
high current is flowing it will just uh make it to run in a loop. So we are just
make it to run in a loop. So we are just concentrating on uh this thyristus only.
concentrating on uh this thyristus only. Thyristus means control switches. Okay.
Thyristus means control switches. Okay. T1, T3, T5, T4, T6, T2. Okay. Now if you
T1, T3, T5, T4, T6, T2. Okay. Now if you see I am just at an output how many how
see I am just at an output how many how many things I have to get. This is my
many things I have to get. This is my input. I'm giving a DC supply. So the DC
input. I'm giving a DC supply. So the DC supply is giving here. So from here I'm
supply is giving here. So from here I'm taking one phase that is Rphase and I'm
taking one phase that is Rphase and I'm connecting it to my load. Similarly from
connecting it to my load. Similarly from the second uh branch I'm taking another
the second uh branch I'm taking another wire and again I'm connecting it to my
wire and again I'm connecting it to my load. From the third branch I'm taking
load. From the third branch I'm taking the other other terminal and I'm
the other other terminal and I'm connecting it to the load. This load
connecting it to the load. This load either can be connected in a star or
either can be connected in a star or delta. So as of now you need not worry
delta. So as of now you need not worry about that star and delta because uh
about that star and delta because uh that thing we have studied during I
that thing we have studied during I think my our uh phases and line wtages
think my our uh phases and line wtages itself. So here if you see this will be
itself. So here if you see this will be this will be connected to your motor or
this will be connected to your motor or something you can just imagine in that
something you can just imagine in that way right. So now this is at the output
way right. So now this is at the output how many waveform I should get for Race
how many waveform I should get for Race I should get one waveform Yphase I
I should get one waveform Yphase I should get one waveform and B phase I
should get one waveform and B phase I should get one waveform. So I'm
should get one waveform. So I'm splitting my output waveform to be R Y
splitting my output waveform to be R Y B. Okay now I'm just writing the
B. Okay now I'm just writing the switching sequences for R phase. Okay.
switching sequences for R phase. Okay. So for Rphase if I want to get a
So for Rphase if I want to get a sinosidal waveform my switch T1 should
sinosidal waveform my switch T1 should be there for positive and T4 should be
be there for positive and T4 should be for my negative. So each switches will
for my negative. So each switches will be conducting for three it should
be conducting for three it should conduct for 360°. So this is also 60 60
conduct for 360°. So this is also 60 60 60 60 like this. So for 360° my T1
60 60 like this. So for 360° my T1 should in the 360 for 180° my T1 should
should in the 360 for 180° my T1 should switch on and for 180° my T4 should
switch on and for 180° my T4 should switch on. So I'm taking my switching
switch on. So I'm taking my switching sequences like this T1 T1 T1 for 180°
sequences like this T1 T1 T1 for 180° that is 30 60 180 right so again I'm
that is 30 60 180 right so again I'm putting like
putting like 60
60 120 180 okay so another T4 for negative
120 180 okay so another T4 for negative of 60 120 180 so positive off I have
of 60 120 180 so positive off I have switched on for 180 and negative I have
switched on for 180 and negative I have switched for 180 so like this T1 and T4
switched for 180 so like this T1 and T4 I have switched ing for Rphase to
I have switched ing for Rphase to achieve Rphase. Now to achieve Yphase
achieve Rphase. Now to achieve Yphase okay for Yphase I need to switch on T3.
okay for Yphase I need to switch on T3. Okay. So as I know the conduction in the
Okay. So as I know the conduction in the rectifier we studied know the uh T1 will
rectifier we studied know the uh T1 will be conducting for 120°. So after 120° I
be conducting for 120°. So after 120° I need to switch my T3. Okay. So T1 is
need to switch my T3. Okay. So T1 is conducting for 60 120 here. So after 120
conducting for 60 120 here. So after 120 I'm switching on my T3. Okay. So T3 is
I'm switching on my T3. Okay. So T3 is switching on T3 T3 T3 for 180°. Okay.
switching on T3 T3 T3 for 180°. Okay. After that T6 should should jump. So T6
After that T6 should should jump. So T6 again will will be conducting for 18
again will will be conducting for 18 another negative of 180°. So T6 T6 T6.
another negative of 180°. So T6 T6 T6. Okay. So again for next phase B phase B
Okay. So again for next phase B phase B phase it is T5 and TS2. So when my T5
phase it is T5 and TS2. So when my T5 will start start to switch on after the
will start start to switch on after the conduction of T3 into 120°. So T3 is
conduction of T3 into 120°. So T3 is completing is 120° here. So from here
completing is 120° here. So from here again T5 I'm switching on. T5 will be
again T5 I'm switching on. T5 will be switched on for 180°. So 60 120 180. So
switched on for 180°. So 60 120 180. So again in the lower half it is T2. So T2
again in the lower half it is T2. So T2 will be connecting for TS2 T2 T2 for
will be connecting for TS2 T2 T2 for another 180°. Are you understanding this
another 180°. Are you understanding this switching pattern? Just comment your
did you understand how I filled this box.
So this is 0 to 60. This is 60 to 120, 120 to 180, 180 to 240, 240 to 300, 300
120 to 180, 180 to 240, 240 to 300, 300 to 360. So did you understand how to
to 360. So did you understand how to fill this?
Just go through the circuit and understand this switching. I just give
understand this switching. I just give another 2 to 3 minutes for this. Okay,
another 2 to 3 minutes for this. Okay, you just go through it.
you just go through it. If you're clear, clear enough, you just
If you're clear, clear enough, you just tell me. We can proceed.
Okay. Is that clear? So shall we proceed to
Is that clear? So shall we proceed to the next table how it has been filled?
Yeah. I will show the waveform. We'll go one by one.
because I want to want you to understand much more better and clearly
much more better and clearly because this inverter circuit only you
because this inverter circuit only you will be feeding it to your motor of your
will be feeding it to your motor of your electrical vehicle.
electrical vehicle. Okay. So this is much important.
So I believe that you understood the concept and I'm just moving on to the
concept and I'm just moving on to the next table. So next is table what you do
next table. So next is table what you do is so here you put the conduction angle
is so here you put the conduction angle that 0 to 60 to 120 120 to 180 180 to
that 0 to 60 to 120 120 to 180 180 to 240 240 to 300 300 to 360 and fill this
240 240 to 300 300 to 360 and fill this column right and then you just put
column right and then you just put switch.
switch. So from 0 to 60, what are the switches
So from 0 to 60, what are the switches on? T1, T6, T5. You just fill it. T1,
on? T1, T6, T5. You just fill it. T1, T6, T5. And 62 to 180. T1, T6, and T2.
T6, T5. And 62 to 180. T1, T6, and T2. T1, T6, and T2. And is 12. Next is 120
T1, T6, and T2. And is 12. Next is 120 to 180. You have T1, T3, T2. So 18 120
to 180. You have T1, T3, T2. So 18 120 to 180. T1, T3, T2. 180 to 240. you have
to 180. T1, T3, T2. 180 to 240. you have T4, T3, TS2. So 180 to 240 I have
T4, T3, TS2. So 180 to 240 I have written T4, T3, T2. And 240 to 300 you
written T4, T3, T2. And 240 to 300 you have T4, T3, T5. So I have written here
have T4, T3, T5. So I have written here 240 to 300 T4, T3, T5. From 300 to 360
240 to 300 T4, T3, T5. From 300 to 360 you have T4, T6, T5. So I have written
you have T4, T6, T5. So I have written 300 to 360 as T4, T6, 3, T5. So again if
300 to 360 as T4, T6, 3, T5. So again if you continue it it the cycles will
you continue it it the cycles will continue. Now I need to check with the
continue. Now I need to check with the output wtages. Okay. So I need to check
output wtages. Okay. So I need to check with what would be my output wtage at
with what would be my output wtage at that point when this switches are on. So
that point when this switches are on. So my next column should be output wtage.
my next column should be output wtage. So before going into filling about this
So before going into filling about this output wtage you just see with this
output wtage you just see with this circuit right now if you could see like
circuit right now if you could see like T1
T1 right? So t_1, t6, t5. Now how I am
right? So t_1, t6, t5. Now how I am going to write the output wtage that is
going to write the output wtage that is very very important. You need to know
very very important. You need to know about one constraint. What is this
about one constraint. What is this constraint? Actually uh in your uh
constraint? Actually uh in your uh YouTube channel I'm just finding a blue
YouTube channel I'm just finding a blue line of strip like like the videos and
line of strip like like the videos and subscribe. Uh behind this actually I've
subscribe. Uh behind this actually I've written that but you are it is not
written that but you are it is not visible for you. I'm just telling you
visible for you. I'm just telling you just write and keep so that you'll be
just write and keep so that you'll be understanding it. Okay. For a balanced
understanding it. Okay. For a balanced circuit, for a balanced circuit, your
circuit, for a balanced circuit, your all the phase voltages should be equal
all the phase voltages should be equal to zero. Okay, in a balanced circuit, if
to zero. Okay, in a balanced circuit, if you sum up all the phase voltages, that
you sum up all the phase voltages, that is a rule. Even Kilov's voltage law
is a rule. Even Kilov's voltage law tells the tells the same thing only. In
tells the tells the same thing only. In a balanced circuit, if you take the
a balanced circuit, if you take the summation of all the voltages, it will
summation of all the voltages, it will be equal to zero. That is VR plus Vy
be equal to zero. That is VR plus Vy plus VB will be equal to zero. If in
plus VB will be equal to zero. If in that case only you can tell the system
that case only you can tell the system is balanced or or else you should tell
is balanced or or else you should tell like the system is not balanced. Okay.
like the system is not balanced. Okay. So VR + Vy + VB will be equal to zero.
So VR + Vy + VB will be equal to zero. Okay. Just write it and keep. Okay. Now
Okay. Just write it and keep. Okay. Now I am asking when VR + Vy plus VB equal
I am asking when VR + Vy plus VB equal to0 then there is no voltage. Correct?
to0 then there is no voltage. Correct? Then how this equation is managed?
If VR plus Vy plus VB is equal to zero, it is a balanced system. Correct? That
it is a balanced system. Correct? That means what? VR should be zero, Vy should
means what? VR should be zero, Vy should be zero and VB should be zero. Right?
be zero and VB should be zero. Right? Then there is no voltage itself. Then
Then there is no voltage itself. Then how this rulers came.
how this rulers came. So how it is how you can understand this
So how it is how you can understand this is VR plus VY is equal to minus VT. you
is VR plus VY is equal to minus VT. you write now VR + Vy will be equal to minus
write now VR + Vy will be equal to minus VB.
VB. Okay. So now you see the equation is
Okay. So now you see the equation is balanced right v + vy will be equal to
balanced right v + vy will be equal to minus vb. So if you take the LCM for
minus vb. So if you take the LCM for this equation and if you check how I can
this equation and if you check how I can write is that
write is that 1x3 of VR plus 1x3 of VY will be equal
1x3 of VR plus 1x3 of VY will be equal to minus 2x3 of VB. So that means what?
to minus 2x3 of VB. So that means what? If VR is equal to 2, V is equal to 2, VB
If VR is equal to 2, V is equal to 2, VB will be 4 minus 4.
will be 4 minus 4. Okay. So that's how the voltage is not
Okay. So that's how the voltage is not becoming zero and then also the system
becoming zero and then also the system is balanced. So this is what you need to
is balanced. So this is what you need to understand. Are you understanding the
understand. Are you understanding the point? So VR VY will be equal to minus
point? So VR VY will be equal to minus VB. This is for an example. Okay. This
VB. This is for an example. Okay. This is for an example. Now we are going to
is for an example. Now we are going to imple implement the same situation in
imple implement the same situation in here also. Okay. So see here these are
here also. Okay. So see here these are three switches. Take the first case
three switches. Take the first case three switches T1, T6, T5. here T1 will
three switches T1, T6, T5. here T1 will be here
be here upper upper row T5 will be here again it
upper upper row T5 will be here again it is on upper row so T6 is lower row so
is on upper row so T6 is lower row so what I can understand is that T1 and T5
what I can understand is that T1 and T5 will be positive and T6 will be negative
will be positive and T6 will be negative the two switches from the same row will
the two switches from the same row will be positive and the one switch which is
be positive and the one switch which is not within the same row will be negative
not within the same row will be negative Is that clear? Like that if you try to
Is that clear? Like that if you try to fill it. So T1 will be like in the R
fill it. So T1 will be like in the R phase. So VR.
phase. So VR. So T6 is here that is Vy and T5 is here
So T6 is here that is Vy and T5 is here that is VB. So VR and VB are in positive
that is VB. So VR and VB are in positive row and Vy is in the negative row. So
row and Vy is in the negative row. So I'm just putting Vy as negative.
I'm just putting Vy as negative. Is that clear? So like that I am just
Is that clear? So like that I am just continuing all the thing right. So now
continuing all the thing right. So now t_1 t6 ts2 so t_s_1 is positive
t_1 t6 ts2 so t_s_1 is positive t6 is negative and tsub_2 is negative
t6 is negative and tsub_2 is negative again. So vr minus vy minus vb similarly
again. So vr minus vy minus vb similarly t_1 t3 tsub2 so t_1 is vr t3 is vy and
t_1 t3 tsub2 so t_1 is vr t3 is vy and t2 ts2 is minus vb. So like this you are
t2 ts2 is minus vb. So like this you are filling it. So next state t4 t3 t2. So
filling it. So next state t4 t3 t2. So the t4 is minus vr. T4 is minus vr and
the t4 is minus vr. T4 is minus vr and t3
t3 t3 is v y vy and t2 t2 is minus vb. So
t3 is v y vy and t2 t2 is minus vb. So similarly t4 t3 t5. So t4 is minus vr.
similarly t4 t3 t5. So t4 is minus vr. T3 is v y and t5 is vb.
T3 is v y and t5 is vb. Okay. Again t4 t6 t5. So t4 t4 is minus
Okay. Again t4 t6 t5. So t4 t4 is minus vr. Okay. T6 is minus vy and t5 is vb
vr. Okay. T6 is minus vy and t5 is vb this. So you have filled this table.
this. So you have filled this table. Okay. this P. Next what I have to
Okay. this P. Next what I have to understand is what is my maximum
understand is what is my maximum voltage. Now only you have to apply the
voltage. Now only you have to apply the concept of taking LCM and filling the
concept of taking LCM and filling the balanced system. So here you have two
balanced system. So here you have two positive that is VR positive and VB
positive that is VR positive and VB positive and the left out is only one
positive and the left out is only one negative. So these two positive will be
negative. So these two positive will be 1x3 VR 1x3 VB and negative will be minus
1x3 VR 1x3 VB and negative will be minus 2x3 VB. So accordingly I'm writing here.
2x3 VB. So accordingly I'm writing here. Is that clear? Are you understanding
Is that clear? Are you understanding this point?
Just apply. If it is yes, we can just fill fill this the other the entire
fill fill this the other the entire column.
So now going to the second thing VR minus VY minus VB. So two negative is
minus VY minus VB. So two negative is there that means what I should put 1x3
there that means what I should put 1x3 here 1x3 here and 2x3 here. So VR VB
here 1x3 here and 2x3 here. So VR VB there are two positive and one negative.
there are two positive and one negative. So what I should do 1x3 VR 1x 3 V and
So what I should do 1x3 VR 1x 3 V and minus 2x3 VB.
minus 2x3 VB. So there are two negative here. So 1x3
So there are two negative here. So 1x3 VR 1x3 VB and 2x3 VY.
VR 1x3 VB and 2x3 VY. So take this VR V two positive is there.
So take this VR V two positive is there. So 1x3 VY 1X 3 VB and - 2x3 VR. So minus
So 1x3 VY 1X 3 VB and - 2x3 VR. So minus VR minus VY and minus so two negative is
VR minus VY and minus so two negative is there 1x 3 VR minus 1x 2 1x3 VY and plus
there 1x 3 VR minus 1x 2 1x3 VY and plus 2x3 VB. So likewise I have filled the
2x3 VB. So likewise I have filled the entire table. Now this I am taking into
entire table. Now this I am taking into the graph now. So this is the graph. So
the graph now. So this is the graph. So in the x-axis if you see 60, 120, 180,
in the x-axis if you see 60, 120, 180, 240, 300, 360, 420. So I have just 400
240, 300, 360, 420. So I have just 400 sorry uh 420. So like this I have
sorry uh 420. So like this I have completely drawn the x-axis. In yaxis I
completely drawn the x-axis. In yaxis I should have two two points that is 1x3
should have two two points that is 1x3 and 2x3. So for three faces VR, Vy and
and 2x3. So for three faces VR, Vy and VB. Okay. So like this I have to draw my
VB. Okay. So like this I have to draw my graph. So I'm just for 0 to 60 I need to
graph. So I'm just for 0 to 60 I need to fill all the three faces. Similarly from
fill all the three faces. Similarly from 60 to 120 I have to draw all the three
60 to 120 I have to draw all the three faces. So 120 to 180 I'll draw all the
faces. So 120 to 180 I'll draw all the three faces from this value.
three faces from this value. Okay. Let's say for example 0 to 60.
Okay. Let's say for example 0 to 60. What is VR? Plus 1x3 VR. So 1x3 I'm
What is VR? Plus 1x3 VR. So 1x3 I'm drawing one graph like this. Next 0 to
drawing one graph like this. Next 0 to 60 V is minus 2x3. So 0 to 60. This is Y
60 V is minus 2x3. So 0 to 60. This is Y face and this is B phase. So minus 2x3
face and this is B phase. So minus 2x3 I'll be getting here. Okay. Here
I'll be getting here. Okay. Here - 2 Vx 3 and then 1x 3 VB. So 1x3 VB.
- 2 Vx 3 and then 1x 3 VB. So 1x3 VB. Okay. So Rphase,
Okay. So Rphase, Yphase and Bphase. So similarly I have
Yphase and Bphase. So similarly I have to draw for entire 360°. So if I draw
to draw for entire 360°. So if I draw like this I'll be getting the waveform
like this I'll be getting the waveform like this. If you sum up this waveform
like this. If you sum up this waveform and if you see it will be pure sinosidal
and if you see it will be pure sinosidal waveform like this. Here you see you'll
waveform like this. Here you see you'll be getting this sort of waveform.
be getting this sort of waveform. Okay. So now I'm just putting this slide
Okay. So now I'm just putting this slide again. You may just go through once with
again. You may just go through once with the waveform and the table which I have
the waveform and the table which I have written.
written. You take just two to three minutes. I'll
You take just two to three minutes. I'll just again continue
again you are asking for sharing TPT that I think uh you may get it. I'm
that I think uh you may get it. I'm ready to serve.
So just to take two minutes and just uh type in your live chat like continue. I
type in your live chat like continue. I may just continue to the next part.
I'm not getting any reply like to continue.
continue. Are you writing it or what?
I'm not getting any reply. Is that any problem?
Is there any delay? Please explain. Please text in the live chat box.
Please text in the live chat box. I'm not getting any reply. I'm not able
I'm not getting any reply. I'm not able to see the reply in your uh
to see the reply in your uh inboxes.
Yeah. Okay. Actually I had a
I had a miscommunication in uh this YouTube
miscommunication in uh this YouTube which I am seeing. I think no delay
which I am seeing. I think no delay right. You just uh come and meet me.
right. You just uh come and meet me. Shall I continue?
>> Yeah. So I'm just uh continuing with the flow. Now we have seen about like
flow. Now we have seen about like rectifier and inverter right. So just uh
rectifier and inverter right. So just uh I just wanted to showcase this. Okay. So
I just wanted to showcase this. Okay. So I told about uh two types of uh inverter
I told about uh two types of uh inverter right wattage source inverter and
right wattage source inverter and current source inverter. If you are
current source inverter. If you are really interested you just go through
really interested you just go through this paper. Uh this is actually they are
this paper. Uh this is actually they are this is not nothing new. So whatever we
this is not nothing new. So whatever we studied theoretically only it is there
studied theoretically only it is there in a paper but they have proven it
in a paper but they have proven it through simulation. If you if you are
through simulation. If you if you are really interested to know about the
really interested to know about the differences between a voltage source
differences between a voltage source inverter and current source inverter,
inverter and current source inverter, you just note down this paper. This will
you just note down this paper. This will actually show this will actually
actually show this will actually showcase like what would be the DC see
showcase like what would be the DC see here. This is actually beautiful, right?
here. This is actually beautiful, right? So what are the dieseling wtages, grid
So what are the dieseling wtages, grid voltages and these everything is same
voltages and these everything is same over here. But when it is operated as
over here. But when it is operated as current source and voltage source, what
current source and voltage source, what would be the switching frequency and how
would be the switching frequency and how would be the other parameter losses?
would be the other parameter losses? they have analyzed it and they have
they have analyzed it and they have given us a comparative proof for
given us a comparative proof for everything as a thing. This I found
everything as a thing. This I found interesting. So if you want just uh note
interesting. So if you want just uh note down and you can just go through it much
down and you can just go through it much more you can understand about like how
more you can understand about like how to adjust the switching frequencies and
to adjust the switching frequencies and these things much more clearly. Okay. So
these things much more clearly. Okay. So everything is bring into this lecture
everything is bring into this lecture series. So definitely it will run out of
series. So definitely it will run out of time. So I'm just giving a just glimpse
time. So I'm just giving a just glimpse of this paper. You can just go through
of this paper. You can just go through it. You may find these sort of
it. You may find these sort of interesting results also over there.
So see here this is what the switching things we have made. Okay. So this is a
things we have made. Okay. So this is a switching arrangement and we have
switching arrangement and we have connected to a motor. So if you want to
connected to a motor. So if you want to do it practically and if you want to
do it practically and if you want to check it see here uh this is a practical
check it see here uh this is a practical arrangement which we have made. Okay. So
arrangement which we have made. Okay. So this is your you know Arduino board.
this is your you know Arduino board. From this Arduino board we are just
From this Arduino board we are just giving the signals like gate signals
giving the signals like gate signals alone we will give like at what time it
alone we will give like at what time it should actually switch on and switch
should actually switch on and switch off. Okay. So accordingly we have made
off. Okay. So accordingly we have made certain arrangement. Here you can see we
certain arrangement. Here you can see we have used resistors and we have used LED
have used resistors and we have used LED to showcase which uh switches on and
to showcase which uh switches on and which switches off so that you can
which switches off so that you can understand much more better. So you can
understand much more better. So you can make if you want to do a hands-on with
make if you want to do a hands-on with among yourself. So at the end of the
among yourself. So at the end of the session we will teach like how to code
session we will teach like how to code this adino and these things. So you may
this adino and these things. So you may learn that and you can incorporate this
learn that and you can incorporate this inverter switching circuit here and you
inverter switching circuit here and you can take a waveform your waveform will
can take a waveform your waveform will be seen like this. Okay. So in real time
be seen like this. Okay. So in real time these are the IGBT switches. So in this
these are the IGBT switches. So in this IGBT switches we have
IGBT switches we have uh so this is actually MOSFET drain
uh so this is actually MOSFET drain source and gate. Okay. So in drain you
source and gate. Okay. So in drain you are giving the pulses here. Okay. From
are giving the pulses here. Okay. From here you are getting the pulses and
here you are getting the pulses and these things you are doing and here you
these things you are doing and here you can see the gate you are giving the
can see the gate you are giving the pulses over here and you are getting an
pulses over here and you are getting an output at the windings. So this is the
output at the windings. So this is the phase of your motor. So if your waveform
phase of your motor. So if your waveform is not pure sinosodal like this your
is not pure sinosodal like this your motor will not run proper. So is that
motor will not run proper. So is that clear? Like this setup also you can just
clear? Like this setup also you can just practice as an add-on. You can just do
practice as an add-on. You can just do it. So this will be in your final stage.
it. So this will be in your final stage. uh now as of now I'm just giving a
uh now as of now I'm just giving a glimpse like uh how these inverters are
glimpse like uh how these inverters are practically made as a circuit to run a
practically made as a circuit to run a motor. Okay. So this is what you can
motor. Okay. So this is what you can understand by this.
understand by this. So you will be at the end of this
So you will be at the end of this session means like on the fifth day that
session means like on the fifth day that is Friday or something you'll be
is Friday or something you'll be learning about about this uh adino kit
learning about about this uh adino kit and how to program it and these things
and how to program it and these things you we can also see this is actually the
you we can also see this is actually the real embedded system coding for that we
real embedded system coding for that we are learning all these things okay in
are learning all these things okay in order to code it properly we need to
order to code it properly we need to know about the circuit right that is
know about the circuit right that is what our aim and we are focusing on that
what our aim and we are focusing on that aspects only. So now how to switch on
aspects only. So now how to switch on the gate pulses. This is actually very
the gate pulses. This is actually very very important for giving that only what
very important for giving that only what we will do. We will we are giving a gate
we will do. We will we are giving a gate triggering circuit right pulses at that
triggering circuit right pulses at that time only our thy restor will switch on
time only our thy restor will switch on or any like uh my mosfet or IGBT will
or any like uh my mosfet or IGBT will switch on. So how I'm going to switch it
switch on. So how I'm going to switch it on is by means of pulse with modulation
on is by means of pulse with modulation technique. This is a technique. Okay. So
technique. This is a technique. Okay. So gener what I will do is that I'll just
gener what I will do is that I'll just create a pulse. that pulse will have a T
create a pulse. that pulse will have a T on period and T off period that I will
on period and T off period that I will provide to the gate signal. So whenever
provide to the gate signal. So whenever it is on high my gate will trigger at
it is on high my gate will trigger at that time current flow will happen.
that time current flow will happen. Whenever it is in low at that time the
Whenever it is in low at that time the gate triggering will be off. At that
gate triggering will be off. At that time my switch is off. Okay. So to
time my switch is off. Okay. So to generate that what I will do is that
generate that what I will do is that simple logic only. This is a comparator
simple logic only. This is a comparator circuit. In this I will give a reference
circuit. In this I will give a reference waveform like this and I will give a
waveform like this and I will give a modulating signal. This will cut this
modulating signal. This will cut this line. This two will compare. This
line. This two will compare. This modicing signal will be a straight line.
modicing signal will be a straight line. This straight line will cut this
This straight line will cut this sawtooth waveform. So when I cut this
sawtooth waveform. So when I cut this sawtooth waveform, wherever the cutting
sawtooth waveform, wherever the cutting process is there at this point and this
process is there at this point and this point, I'll be getting a pulse over
point, I'll be getting a pulse over here.
here. Okay, this is for an example. So by
Okay, this is for an example. So by adjusting the width of this pulse, what
adjusting the width of this pulse, what I can do is I can adjust the on period
I can do is I can adjust the on period and off period. Okay, so I should
and off period. Okay, so I should maintain the 50% on period and 50% off
maintain the 50% on period and 50% off period. So this is what actually the
period. So this is what actually the pulse signal. So to how much wtage I can
pulse signal. So to how much wtage I can give. For example, if my switch is
give. For example, if my switch is operating at five voltages. So I have to
operating at five voltages. So I have to maintain a magnitude of 5 volt. This is
maintain a magnitude of 5 volt. This is the amplitude. This amplitude I should
the amplitude. This amplitude I should maintain at 5 volt. Okay. So if I want
maintain at 5 volt. Okay. So if I want to get uh on period and off period of
to get uh on period and off period of exact 50%age uh duty cycle I need to
exact 50%age uh duty cycle I need to maintain 50% on and 50%age off. So this
maintain 50% on and 50%age off. So this is what I should maintain. So this is
is what I should maintain. So this is called as pulse with modulation
called as pulse with modulation technique. This pulse we will feed this
technique. This pulse we will feed this pulse to the gate triggering point of
pulse to the gate triggering point of the transistors. So triggering point of
the transistors. So triggering point of the transistor we will input we will
the transistor we will input we will give as an input for this one only. So
give as an input for this one only. So if I am having for example in an
if I am having for example in an inverter circuit how many switches I
inverter circuit how many switches I have totally six switches for each and
have totally six switches for each and every switch I should have a drive
every switch I should have a drive circuit for each and every switch I
circuit for each and every switch I should have a drive circuit. So if if I
should have a drive circuit. So if if I am keeping one switch for that I should
am keeping one switch for that I should give pulses. So for that pulses I should
give pulses. So for that pulses I should have a dry circuit. So totally there are
have a dry circuit. So totally there are six switches. So I am in need to have a
six switches. So I am in need to have a six switches for six uh sorry six drive
six switches for six uh sorry six drive circuits for six switches and six dry
circuits for six switches and six dry circuit will create this sort of pulses.
circuit will create this sort of pulses. So is that clear? So this is how the
So is that clear? So this is how the gate triggering signals are given to the
gate triggering signals are given to the switches. This we can see in again we
switches. This we can see in again we can see this also in our demo session in
can see this also in our demo session in the afternoon we are planning to have a
the afternoon we are planning to have a demo of the circuits right we will do
demo of the circuits right we will do that also right
that also right see here. So you can use any sort of
see here. So you can use any sort of waveform here. Okay. Single pulse with
waveform here. Okay. Single pulse with modulation, multiple pulsation.
modulation, multiple pulsation. Generally we will use sinosidal pulse
Generally we will use sinosidal pulse with modulation that is SPWM technique.
with modulation that is SPWM technique. SPWM technique. Okay. Sinos space vector
SPWM technique. Okay. Sinos space vector pulse with modulation also is there.
pulse with modulation also is there. SVPWM. So that is also is there many
SVPWM. So that is also is there many type of is there but for easy
type of is there but for easy understanding generally we will use uh
understanding generally we will use uh cost effective and uh for control to
cost effective and uh for control to develop a control system also the
develop a control system also the cinosidal pulse with modulation serves
cinosidal pulse with modulation serves as a good thing. So you can just uh go
as a good thing. So you can just uh go through it and you can find it. So here
through it and you can find it. So here what we will do we will have a carrier
what we will do we will have a carrier waveform like this we have a sawtooth
waveform like this we have a sawtooth and modulating will be having a
and modulating will be having a sinosidal waveform. So we are getting a
sinosidal waveform. So we are getting a sinosidal waveform here. Okay. So what
sinosidal waveform here. Okay. So what you can understand is that
you can understand is that you are going to cut into a this part
you are going to cut into a this part right. So we are having a different on
right. So we are having a different on period and off period. Okay. So what you
period and off period. Okay. So what you can understand is this this one pulse
can understand is this this one pulse and this pulse is for one cycle only and
and this pulse is for one cycle only and for lower off you will get another
for lower off you will get another cycle. So like this for one cycle itself
cycle. So like this for one cycle itself you are switching on and switching off
you are switching on and switching off for three times one positive off.
for three times one positive off. Similarly for one you are switching off
Similarly for one you are switching off switching off for three times. So this
switching off for three times. So this is called as actually the switching
is called as actually the switching frequency. Okay. So through pulse with
frequency. Okay. So through pulse with modulation technique what you can get is
modulation technique what you can get is that you can still get a pure sinosidal
that you can still get a pure sinosidal waveform at your output point because
waveform at your output point because you are creating more number of sample
you are creating more number of sample time more number of samples. See this is
time more number of samples. See this is what I I was mentioning in this point.
here. See here instead of one pulse like this through pulse with modulation what
this through pulse with modulation what you can create is that you can create
you can create is that you can create this many sort of steps. So when you
this many sort of steps. So when you create these many types of steps
create these many types of steps ultimately you are trying to achieve
ultimately you are trying to achieve this sort of sinosidal waveform
this sort of sinosidal waveform inverter. So is that clear what why we
inverter. So is that clear what why we need to switch on and switch off using
need to switch on and switch off using pulse with modulation technique that
pulse with modulation technique that many times in order to get a smooth
many times in order to get a smooth waveform at the output
waveform at the output for one off for one half of the
for one off for one half of the sinosidal for one half of this square
sinosidal for one half of this square wave we are switching on switching off
wave we are switching on switching off through pulse with modulation n number
through pulse with modulation n number of times. See for example 1 2 3 4 5 6
of times. See for example 1 2 3 4 5 6 you are creating a six levels. Okay. So
you are creating a six levels. Okay. So six levels you are creating. Six times
six levels you are creating. Six times you are switching 6 + 6 12 6 + 6 12. So
you are switching 6 + 6 12 6 + 6 12. So 12 times you have switched on and switch
12 times you have switched on and switch off this puls through puls modulation.
off this puls through puls modulation. Because of that what you are able to get
Because of that what you are able to get is this sinos this square wave inverter
is this sinos this square wave inverter square wave output has become a
square wave output has become a sinosidal waveform. Is that clear why we
sinosidal waveform. Is that clear why we are going to use an pulsive modulation
are going to use an pulsive modulation technique in switching on and switching
technique in switching on and switching off?
So I'm getting only one S. So others, what about others?
So is that clear why we are using pulse with modulation technique?
So using that what you can do is you can take different level of outputs. Because
take different level of outputs. Because of that what happens is at your output
of that what happens is at your output at your output point if your output is a
at your output point if your output is a square wave this pulse with modulation
square wave this pulse with modulation technique will help you to get in a such
technique will help you to get in a such a way that it is somewhat sinosidal.
a way that it is somewhat sinosidal. Okay. So this is the major point of
Okay. So this is the major point of pulse with modulation technique. So
pulse with modulation technique. So using pulse with modulation technique
using pulse with modulation technique only you'll be switching on and
only you'll be switching on and switching off the switches which is
switching off the switches which is being present inside your inverter
being present inside your inverter circuit. If you're going to use
circuit. If you're going to use rectifier also, rectifier also if you're
rectifier also, rectifier also if you're using thyristus means by the at that
using thyristus means by the at that time also you can use this puls
time also you can use this puls modulation technique to use for it.
modulation technique to use for it. Right?
So here are certain things of switching on and switching off of your thyristers
on and switching off of your thyristers switches. Okay. First thing is
switches. Okay. First thing is triggering angle or fire angle. It is
triggering angle or fire angle. It is the angle at which the ACR gets turned
the angle at which the ACR gets turned on and starts conducting. So this is the
on and starts conducting. So this is the point at which you are turning on the
point at which you are turning on the SCR and it is trying to conduct. Okay.
SCR and it is trying to conduct. Okay. This is the angle where the designer
This is the angle where the designer actually applies the gate pulse to
actually applies the gate pulse to control its ACR. So you are explain you
control its ACR. So you are explain you are putting the gate pulse right. It is
are putting the gate pulse right. It is exactly it should be off at this point.
Okay. Next commutation angle or extension angle. Okay. Next angle is
extension angle. Okay. Next angle is commutation angle or extension angle.
commutation angle or extension angle. These three parameters are very
These three parameters are very important to control the switches. If
important to control the switches. If you were asking about like why it is not
you were asking about like why it is not starting from zero right these things
starting from zero right these things can be corrected using these these
can be corrected using these these parameters. Okay. So what is commutation
parameters. Okay. So what is commutation angle or extension angle beta. Okay it
angle or extension angle beta. Okay it is the angle at which which is turned
is the angle at which which is turned off that is it is STR is turned on
off that is it is STR is turned on during the triggering angle and it is
during the triggering angle and it is turned on off at the commutation angle.
turned on off at the commutation angle. So you're just exactly turning it off at
So you're just exactly turning it off at the commutation angle. Okay. So for AC
the commutation angle. Okay. So for AC resistive load application normally the
resistive load application normally the commutation takes place at every zero
commutation takes place at every zero crossing. That is wherever the zero
crossing. That is wherever the zero crossing is happening in a pulse
crossing is happening in a pulse withidth modulation at that time the
withidth modulation at that time the commutation angle will happen. Okay. So
commutation angle will happen. Okay. So the triggering and commutation is
the triggering and commutation is nothing but during your pulse with at
nothing but during your pulse with at what time you are switching on the gate
what time you are switching on the gate pulse that is called as triggering angle
pulse that is called as triggering angle that is at that particular point only
that is at that particular point only your switches is turning on and during
your switches is turning on and during the extension angle you are just
the extension angle you are just switching off the switches. Is that
switching off the switches. Is that clear? And finally you have another
clear? And finally you have another angle that is conduction angle.
angle that is conduction angle. Conduction angle is the angle between
Conduction angle is the angle between your tire triggering angle and your
your tire triggering angle and your commutation angle. Up to that angle your
commutation angle. Up to that angle your switches will on. For example, we have
switches will on. For example, we have checked that 0 to 60°. Right? If it is 0
checked that 0 to 60°. Right? If it is 0 to 60°, 0° is your triggering angle. 60°
to 60°, 0° is your triggering angle. 60° is your commutation angle. Conduction
is your commutation angle. Conduction angle is 0 to 60. Is that clear? Are you
angle is 0 to 60. Is that clear? Are you able to get what are these three angles
able to get what are these three angles are about?
Yes. So coming here if your firing angle is zero. Okay. See here if I change the
is zero. Okay. See here if I change the firing angle. Okay. That is your
firing angle. Okay. That is your triggering angle. If I'm changing the
triggering angle. If I'm changing the triggering angle accordingly you see
triggering angle accordingly you see here the waveforms are getting deviated
here the waveforms are getting deviated in the same phase. If your firing angle
in the same phase. If your firing angle is zero right your output waveform you
is zero right your output waveform you see here it is like this. It is you are
see here it is like this. It is you are not at all getting any dip point like
not at all getting any dip point like this. Okay. If I making the firing angle
this. Okay. If I making the firing angle alpha that is this firing angle to be
alpha that is this firing angle to be that is triggering angle to be 30 then I
that is triggering angle to be 30 then I will get a dipping at that 30° like
will get a dipping at that 30° like this. See here you can find a dipping
this. See here you can find a dipping whereas here you cannot find any
whereas here you cannot find any dipping. If I am fire if my firing angle
dipping. If I am fire if my firing angle is more than 30 then again still more my
is more than 30 then again still more my amplitude will get increased because my
amplitude will get increased because my dipping angle is still increasing and I
dipping angle is still increasing and I will get a delay over here. See here
will get a delay over here. See here this delay. Okay. So based upon your
this delay. Okay. So based upon your firing angle you will manage to make it
firing angle you will manage to make it make your waveform to start at zero or
make your waveform to start at zero or some other triggering point. So this is
some other triggering point. So this is the based upon your application this
the based upon your application this firing angle can be actually changed.
firing angle can be actually changed. Okay this generally in EV if you take we
Okay this generally in EV if you take we are not we are going to use this
are not we are going to use this inverter just to run the motor. Other
inverter just to run the motor. Other than that we don't have any requirement
than that we don't have any requirement to convert your DC to AC generally.
to convert your DC to AC generally. Okay. So for running the motor you need
Okay. So for running the motor you need not worry about this firing angle
not worry about this firing angle because this firing angle is actually
because this firing angle is actually shows more influence over the resistive
shows more influence over the resistive load not on the inductive load or
load not on the inductive load or something. So you just you while your uh
something. So you just you while your uh simulation you may just understand it.
simulation you may just understand it. Okay. Okay. So other than that you need
Okay. Okay. So other than that you need not worry about that much about this
not worry about that much about this firing angle.
firing angle. Next if you take a traction inverter the
Next if you take a traction inverter the inverter that is directly being used to
inverter that is directly being used to a electric wave electric motor this
a electric wave electric motor this actually actually drives the motor
actually actually drives the motor actually it minimizes switching
actually it minimizes switching switching losses and it has it should
switching losses and it has it should have more thermal efficiency and it
have more thermal efficiency and it should be treated in such a way that it
should be treated in such a way that it should be having regenerative braking as
should be having regenerative braking as well as recharge the battery. That means
well as recharge the battery. That means what? I should place the bridge circuit
what? I should place the bridge circuit in such a way that it is acting as a
in such a way that it is acting as a inverter as well as a rectifier because
inverter as well as a rectifier because see here from the battery you are going
see here from the battery you are going to the motor control unit and motor
to the motor control unit and motor control unit to the gate driver and
control unit to the gate driver and you'll be having a inverter circuit.
you'll be having a inverter circuit. This is your inverter circuit and then
This is your inverter circuit and then it is going given to the motor. Okay. So
it is going given to the motor. Okay. So if it is operating as a motor from
if it is operating as a motor from battery the voltage is taken. The motor
battery the voltage is taken. The motor control unit will decide how much gate
control unit will decide how much gate pulses has to be given to the gate
pulses has to be given to the gate driver and the gate driver will create
driver and the gate driver will create the great gate uh pulses for six
the great gate uh pulses for six switches. Six gate pulses are given and
switches. Six gate pulses are given and it is taken to the inverter module. From
it is taken to the inverter module. From here your motor is running. Now it is
here your motor is running. Now it is operating as a inverter from battery DC
operating as a inverter from battery DC to motor AC. The total is actually
to motor AC. The total is actually inverter. Now during regeneration the
inverter. Now during regeneration the motor has to operate as generator. Okay.
motor has to operate as generator. Okay. Now the motor has to feed the current
Now the motor has to feed the current back. So now the current is coming back.
back. So now the current is coming back. The inverter now is operating as a
The inverter now is operating as a rectifier. Accordingly the gate pulses
rectifier. Accordingly the gate pulses will change to a rectifier model. This
will change to a rectifier model. This motor control unit will take care of it.
motor control unit will take care of it. Now it is taking care of the rectifier.
Now it is taking care of the rectifier. Now when it is rectifier again it is
Now when it is rectifier again it is being given AC is converted to DC and
being given AC is converted to DC and this DC will be given back to the
this DC will be given back to the battery.
battery. Okay. This is what actually in
Okay. This is what actually in electrical vehicle rectifier role and
electrical vehicle rectifier role and inverter role is are for. Are you
inverter role is are for. Are you understanding the real fact and factual
understanding the real fact and factual about the rectifier and inverter? Why I
about the rectifier and inverter? Why I taught this for you?
taught this for you? Because when you operate this as a motor
Because when you operate this as a motor or generator your current flow will be
or generator your current flow will be in opposite direction. Your inverter
in opposite direction. Your inverter should be your your this
should be your your this converter module should be in such an
converter module should be in such an aspect like it should operate it should
aspect like it should operate it should be able to operate as a rectifier as
be able to operate as a rectifier as well as inverter. That is very very
well as inverter. That is very very important because you need to operate
important because you need to operate this as a motor also or you need to
this as a motor also or you need to operate this as a generator also for
operate this as a generator also for your battery saving. Accordingly your
your battery saving. Accordingly your pulse with modulation technique also
pulse with modulation technique also should change and gate pulses switching
should change and gate pulses switching on and switching off pattern you studied
on and switching off pattern you studied know in the in the beginning of the
know in the in the beginning of the session T1 T2 for 60° like that that
session T1 T2 for 60° like that that should also be changed. So this is what
should also be changed. So this is what about your chopper rectifier and
about your chopper rectifier and inverter. Are you getting this? If you
inverter. Are you getting this? If you have any doubt you can just ask me. We
have any doubt you can just ask me. We have some five minutes of time. So if
have some five minutes of time. So if you have any doubt you can just ask me.
you have any doubt you can just ask me. Still we have this type of this is the
Still we have this type of this is the entire unit. You can see here entire
entire unit. You can see here entire unit of your traction motor here. This
unit of your traction motor here. This is the motor right. So from battery you
is the motor right. So from battery you have a battery disconnect unit. You this
have a battery disconnect unit. You this is this is a actual drawing of uh
is this is a actual drawing of uh electrical vehicle. Here you can see the
electrical vehicle. Here you can see the IGBT model. This is the power stages
IGBT model. This is the power stages right from battery you have a battery
right from battery you have a battery discharge connect unit. So if you want
discharge connect unit. So if you want to disconnect the battery at that time
to disconnect the battery at that time for charging and discharging you can you
for charging and discharging you can you have a unit for it separately and you
have a unit for it separately and you have a DC link capacitors you have
have a DC link capacitors you have discharge unit again and you then give
discharge unit again and you then give your current and voltage input to this
your current and voltage input to this controller module from there three
controller module from there three phases from morning you are studying
phases from morning you are studying about this only.
about this only. Okay this and this.
Okay this and this. Okay. So yesterday we studied about uh
Okay. So yesterday we studied about uh chopper, right? Those choppers will be
chopper, right? Those choppers will be there in this type of unit
there in this type of unit TC to DC conversion for power
TC to DC conversion for power transmission. Okay. So everything is
transmission. Okay. So everything is controlled through this microcontroller.
controlled through this microcontroller. So our role of this session is for about
So our role of this session is for about embedded systems. So to give input to
embedded systems. So to give input to this you need to study about all these
this you need to study about all these parameters
parameters and finally we will study about this
So this is actually taken this is confidential this is taken from an
confidential this is taken from an electrical vehicle unit. So you may just
electrical vehicle unit. So you may just go through it
if you have any doubt. So morning we were studying yesterday we are studying
were studying yesterday we are studying about these things and morning you
about these things and morning you studied about these things. We will have
studied about these things. We will have a demo of uh these things whatever we
a demo of uh these things whatever we have studied as chopper, rectifier and
have studied as chopper, rectifier and inverter in the afternoon session and
inverter in the afternoon session and maybe tomorrow we will be planning as
maybe tomorrow we will be planning as the demo session is over we may plan for
the demo session is over we may plan for motor how this uh signals are given to
motor how this uh signals are given to the motor and how the motor is running
the motor and how the motor is running and we will see the demo of this circuit
and we will see the demo of this circuit along with the motor and how we can
along with the motor and how we can control the motor in attraction and then
control the motor in attraction and then finally we will go in for this
finally we will go in for this microcontroller unit
microcontroller unit through Ardin.
So still we have 3 minutes time you can just go through it.
So still we have to look about some some more uh points here. it takes nearly 10
more uh points here. it takes nearly 10 to 15 minutes of this uh content. So
to 15 minutes of this uh content. So still we have uh three to two minutes
still we have uh three to two minutes only time for the morning session. So
only time for the morning session. So what I will do is that I'll just uh give
what I will do is that I'll just uh give a brief introduction about uh that falls
a brief introduction about uh that falls in the afternoon session and we'll
in the afternoon session and we'll continue with the demo with similing
continue with the demo with similing software. Is that clear?
software. Is that clear? Once again, explain inverter table once.
Once again, explain inverter table once. Okay, I will explain it in the afternoon
Okay, I will explain it in the afternoon session or once the demo is over, I'll
session or once the demo is over, I'll try to explain it. Don't worry, okay?
try to explain it. Don't worry, okay? Because here we are running out of time.
Because here we are running out of time. We have only 2 minutes. So, just go
We have only 2 minutes. So, just go through this uh
through this uh follow this network. Actually, if you if
follow this network. Actually, if you if you are able to create a snapshot, you
you are able to create a snapshot, you can snapshot this thing and you can go
can snapshot this thing and you can go through it. Here
you can see like bug boost pre-registers.
So whatever you have studied it is within the electrical vehicle system you
within the electrical vehicle system you are not studying which is not uh there
are not studying which is not uh there in a system right. So everything is
in a system right. So everything is related to electrical vehicle system
related to electrical vehicle system only. We are just going through one one
only. We are just going through one one subcategories. Okay. If time permits uh
subcategories. Okay. If time permits uh I will try to cover up charger also. I
I will try to cover up charger also. I think time will not be that much
think time will not be that much sufficient to cover charger. If it is
sufficient to cover charger. If it is there, I'll just run up as a snap. Yeah.
So I think I am concluding over here. I think you don't have any doubt. Uh I
think you don't have any doubt. Uh I have just got a request of explaining
have just got a request of explaining inverter circuit once again. Definitely
inverter circuit once again. Definitely I'll do it as we as we have any time. We
I'll do it as we as we have any time. We will just plan it in a session. If I
will just plan it in a session. If I have some 10 to 15 minutes at the end
have some 10 to 15 minutes at the end part again I will go with the inverter
part again I will go with the inverter and I will explain it. Don't worry. So
and I will explain it. Don't worry. So I'm concluding this session here. Thank
I'm concluding this session here. Thank you.
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