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Embedded Systems and Design & Development - Feb 23, 2026 | Afternoon | VisionAstraa EV Academy

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Summary

Core Theme

This content provides a foundational understanding of power electronic switches, specifically comparing BJTs and IGBTs, and then delves into DC-DC converters (choppers), explaining their types (buck, boost, buck-boost) and operational principles. It emphasizes their application in electrical vehicles and introduces the upcoming topics of rectifiers and inverters.

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Yeah,

I welcome you all back to the session.

So uh here uh just we ended up in uh

bipolar jension transistors and how do

like uh in what are the configurations

they are available. So when you are uh

obviously in uh

electrical vehicle application uh we are

going to use this bipolar junction

transistor by means of switches. So we

are just worried about operating this

bipolar junction as a switches. So we

fixed in with a certain type like common

based type of configuration for your uh

application. So here we ended up like

this is by bipolar junction transistor.

So we will just go on with the other

So the next type of transistors that is

they are field effect transistors. So in

this field effect transistors as we all

as we have discussed in the previous

itself like uh junction transistors are

used for low current application and

sorry low voltage application and IGBTs

are used for low low current

applications. So here if you see uh

there are different types of uh field

effect transistors uh like MOSFET and

these things. So we are not actually

worried about different types of

switching switching circuits here. We

are actually worried about like

junction transistors and field effect

transistors. So in this aspect we are

just going with IGBT. So IGBT is nothing

but it is a combination of BJT as well

as MOSFET. So just like that uh morning

we saw about like BJT right. So this BJT

will be having like a bipolar junction

transistors have three terminals

collector, emitter, base whereas this

MOSFET will have drain, source and gate.

Okay. So IGBT is the combination of

MOSFET plus BJT. Okay. So how this we

are not now I'm not getting into a

deeper topic like how MOSFET is working

and how I emit BJT is working and

ultimately how HGBD is going to work. So

instead we are going to see it in a

different way. As you all know

everything is the combination of uh PNP

type of semiconductors. So here you see

like PT type semiconductor N type of

semiconductor and you do have silicon

oxide. These things actually you can

just go through with other available uh

YouTube video sources. So there you can

see in deep like how these things are

practically working. But what I am here

to tell is about. So here you have three

terminals. I'll just give a brush up

about it. Gate, collector and emitter.

From that what you can understand is

that it is a output wise it will behave

like a bipolar junction transistor.

Whereas its input

uh you will be having as a MOSFET.

Right? So here you have two terminals to

have a little amount of light on it. Uh

the voltage across collector and emitter

will be always existing. Right? But only

when you give a triggering pulse to the

gate whenever the gate is given with

some voltage at that time only current

will flow from collector to emitter. So

this is the logic behind it. So uh

instead of going in for chemical

combination of that how it is working

that things have been briefly discussed

with respect to BJT.

So it is it will also work in a similar

way only. But thing is that the control

technique the control technique is very

simple. Your uh load will be if you want

to connect a lamp in between uh you want

to connect a lamp and you want to blow

it turn it on and turn it off with uh

the help of this IGBT. What you have to

do is you just connect a lamp it will

not glow. But if you measure the voltage

wtage will be there across your bulb.

But when you just give a positive high

to the gate terminal at that time the

bulb will glow. If it is low at that

time the bulb will get off. So like this

only the switches is operating actually.

So now if you see technically it will

work like this only a masset is there

and it's uh drain terminal is used as a

base of your uh IGBT sorry BJT here. So

now if you see the collector terminal of

a BJT is there, emitter terminal of a

BJT is there and gate terminal of your

MOSFET is there. Okay. So this will

actually work under the principle of

your uh BJT itself. See here collector

current is flowing at last emitter

current has to flow. What is my logic

for BJT? My collector current should be

equal to my emitter current. If I able

to do that then I understand my switch

is on. So how do I do that? I just give

a gate voltage to the this terminal. If

I give a high pulse then what happens is

this terminal will get its voltage. At

that point gate gate signal will be

given. At that point your collector

current will be equal to the emitter

current. If you do so

then your uh switches ultimately going

to turn on. So this is how the IGBTs

will work. So this IGBDs are used in the

predominantly in most of the power

electronic circuit which is being used

in the inside an electrical vehicle. Right?

So this is a basic difference between a

BG and an IGBT. Okay. The first point

about it terminals. BJT has three terminals.

terminals.

emitter, base and collector. IGBT also

has the same three terminals but

emitter, collector and gate. Coming to

the control quality, BJ BJT is a current

control device whereas IGBD is a voltage

control device. You control the base

current of your BJT. Whereas in IGBT you

control the voltage between gate and the

emitter that is gate emitter voltage. By

controlling it the output will be

controlled to the current of your base.

So in this logic only these two

transistors will be working. Coming to

control terminal the base terminal has

the control on the operation of BJT

whereas gate terminal has the control on

the operation of IGBT.

drive circuit BJT as a complex drive

circuit. Whereas if you see when you

construct a drive circuit using an IGBT,

it is relatively simple when compared to

BJT. Switching speed is low in a case of

BJT. Whereas for an IGBT, the switching

speed is comparatively high. Switching

time of a BJD is an order of 10 microsconds

microsconds

whereas it is an it is half than that

often be in the case of IGBT that is 0.5 microconds

microconds

drive power has a very require BJT

requires very large drive power that is

the voltage and current consumption of a

BJT is much more higher when compared to

that of an IGBT. So since you are going

to use the switches inside an electrical

vehicle, it is depending upon the

battery voltage to utilize it. Right? So

if it is going to consume more wtages

and current, it ultimately ends up in

draining of battery that will affect

your range of your vehicle. So this is

this also pays a small point in

increasing your range. Next point

switching power losses. for BJT the

switching losses are relatively high

whereas in IGBT the switching losses are

less than the BJT. Okay, switching

frequency. So coming to switching

frequency this is a very important point

a BJT the switching frequency is about

20 KOHZ max whereas here you can go up

to 160 kHz. Okay. So next the input

impedance imped impedance is low in a

case of PJT whereas in the case of IGBD

it is high. Now

safe operating area BJT has a narrow

safe operating area whereas IGBT has the

safe area is wider than that of a BJT.

Okay that is the operating voltage

range. Okay. The operating wtage range

is very very limited with respect to a

BJT. Whereas in case of IGBT you can go

for wide range of operation

PJT is power and capability is very low

when compared to that of an IGBT

onstate resistant temperature

coefficient. Okay. So how much it can

withstand the temperature. Okay. So BJD

has a negative temperature coefficient

of onstate resistance. Whereas IGBT has

positive temperature coefficient.

Application of BJD is low power

switching devices as an amplifier. IGBT

extensively used as a switching devices

in inverter circuits. So basically in

our uh power electronics used in

electrical vehicle we use actually

switching devices only for inverter

circuit. So we prefer IGBT. So if you

ask me like sir we have a junction trans

transistors field effect transistors we

have IGBT so which is better than that.

Okay. So we cannot tell like see uh we

cannot tell if I if I want to replace

IGBT as BJT or BJT as MOSFET like that.

So we cannot tell like that because each

switch has its own advantages and

disadvantages. The call has to be taken

by the designer that is yourself. So if

you are going to design a circuit and if

you are building a circuit for certain

application you have your own

constraints like I can compromise with

certain points correct or not you you

you you may go like this point can be

compromised by myself because instead of

that I can concentrate on some other

point if you have that sort of

understanding you can go with any

switches but compromise should not

affect the performance of the entire

system. So if your compromise is going

to affect the performance of the entire

vehicle system then it should not that

that is not a right decision right. So

end of the day what you have to consider

is that you have to check with the

application and application efficiency

should be good by using any of your

switches that should be in your mind and

with that respect only you have to

choose your switches. In our case, most

of the inverter we are we are in uh our

uh electrical vehicle system we are

going to purely depend upon the

operating this transistor as switches

only. So if it is going to be a switches

it should it should handle more or more

of uh switching frequency with less

switching losses. In that case we can

use either our IGBT or MOSFET for your

application. Right? So this is what

Now we are coming into the next

important topic that is power

electronics right. So now I just wanted

to now I have just ended with all type

of essential things. Okay essential

things in the sense we have studied

about like what is the basics about

electricals that is electrical circuits

that is very much necessary to figure

out the circuit to trace the circuit and

do the fault diagnosis systems. How to

understand the system? how to analyze it

and how to calculate it. Correct? In the

basic electronic system, we understood

what are the components available, how

do they behave when connected in

different sorts of networks and

circuits. And finally, we saw about

different types of switches. Now, what

we are going to do is that using the

switches how we are going to construct a

circuit. So, now we are entering into

the power electronics part of the Okay.

So power electronic

part of your electrical vehicle system.

Okay. Now as of now if you have any

doubt in switches or any related uh

things you may just ask I will just give

a break of 1 minute you may just comment

your uh things in the live chat and

accordingly you may I may address your

answers and then uh address your

questions sorry and we can proceed with

Now actually we are going to building

few circuits to which is actually used

by electrical vehicle system. So I think uh

all are asking about good afternoon and

uh time of starting the classes time

So yes, so uh as this thing is uh I

don't see any queries from your side.

I'm just pro proceeding with the circuit

construction. So in this power

electronic circuit what are the circuits

actually there inside an electrical

vehicle system. So the first question is

that right? So where are the what are

the conversions we have to make and

these things. So for that you just

imagine like uh what are the systems

connected with the electrical vehicle

from input to the output input in the

sense like uh from the grid when I

connect my electrical vehicle to the

grid from there my role starts right and

where it ends up means when it when it

is uh getting utilized and my electrical

energy is transmitted to the wheel as a

mechanical motion till the till that

point my point point is ending and that

is like working principle. Now apart

from that you have to understand another

thing. If I want to optimize my system

for example if your vehicle is running

by itself now you want to just you use

the motor to be a generator and you have

to regenerate the principle and again

restore the energy as a kinetic energy

to electrical energy and you have to

restore it into into your energy system

called battery. If you're doing that

again that requires another type of

control system. So if you just think

about it you have what are different

types of different types of different

types of circuits requirement right here

if you want to transmit the power in

electrical vehicle. If you want to

transmit the power from one part to the

other part for example you just imagine

the circuit which I have shown in the

very beginning that is from your battery

you are just transmitting the power to

controller drive circuit. Okay your

battery is having a DC power and that DC

power is being fed to the

uh power electronic control drive which

is driving the motor. Okay. Apart from

that there are many electrical and

electronic components within the

vehicle. For example, what lighting

systems, infotainment and uh you have

other air conditioning systems. So many

systems are there. For that also you

need to transmit the power from the

battery. Right? The inverter power

requirement is something different from

this component level of uh equipments

which is there in the vehicle. So how to

split the power and give because we do

have only one battery right from there

we need to transmit the system. So

though the components may work in DC or

AC that is my secondary question first

how we are going to transmit the power.

Okay. So we are going to transmit the

power from battery to other part of the

system which is there in the electrical

vehicle. Now I all the equipments are

operating at different wtage ranges and

current ranges. So I need to transmit

the same power of battery to all the

systems and component level. Now what I

have to do I need to make certain

necessary arrangement so that that

particular component is going to receive

that much amount of voltage and current

which is required by the load. So there

I I need to transmit the power. So for

that I need to build a circuit. Now from

the grid I need to store the energy to

my battery. So grid is of AC whereas I'm

going to have my battery as my DC. So I

need to convert that AC to DC. Now there

also I need to have a circuit. Similarly

there may be certain applications which

is running only in AC AC supply. So when

I require only AC supply, I do have a

energy source only battery which will

give only me DC supply. So again there I

have to convert my DC to the AC right. So

so we have to take this part into

consideration and we have to build the

circuit for these things right. So in

this aspect only we are seeing about

going to see about these three topics

that is chopper rectifier and inverter.

power electronics. So what is actually a

powerronics? So here we are going to see

about some electronic circuit that is

going to operate in a high voltage.

What was your question?

Can you retype it? I'm not able to find

Okay. So I'm just continuing with the

session. I think uh

something which is irrelevant is going

on. Right. Thank you. So now

uh yeah so what this poweronic systems

are usually used

okay I you want to reduce my speed okay

fine slowly I'm going so power

powerronic systems are widely used in

different types of applications that is

power generation power transmission

power distribution and power control. So

you understand this flow right?

Generation, transmission, distribution

and control. So if you see the meaning

of power electronic circuit is

integrating different parts of the

components. So here you see if you have

a micro grid, it serves as the interface

to all type of application.

Okay. So here you can see like uh this

is general explanation. So,

so from my electrical grid if you want

to connect it to a micro grid say for

example a battery or something

definitely you require a electronic

interface. Similarly from my energy

storage system okay so from there if you

want to have different types of micro

grid there also you require a paratronic

interface. If you're varying load like

AC to DC loads different loads are there

and you want to utilize it for your

micro grid or something anything which

you want to connect that is very simple

only I have quoted these words that is

if you want to generate the power

transmit the power distribute it and

control it definitely you require a

polronic circuit for it. So this is the

brief introduction about the polronics

and this is how it is important for any

system right now just see here this is

the powerronic system. This is how it

works. You give a input power you you

you have a power converter. This is your

powerronic circuit and it will give a

output power. Your input require

required output power. If your input

power may vary at any cost but you fix

your output power should be in this way

accordingly you build a circuit and that

circuit is called as power polonic

circuits and this is the uses of this

power converters right now if still if

you want to have a closed loop operation

you have to have a feedback like this

much should be your reference and

accordingly this controller has to work

for that also you can to create some

feedback and create a compensation

circuit and based upon that compensation

circuit you can control your powerronic

devices so that you'll be having a

closed loop operation. Closed loop

operation means what your output based

upon your output you can even change

your input given to your system or you

can also correct the error between the

output power and your input power. Okay.

So this is actually the role of your

power electronic devices. Now what are

the basic types of power converters?

First, a power converter can convert a

AC input to a DC input.

Next, it can convert a DC to DC power.

Next, your input can be a DC and your

output can be AC.

Next, your input can be AC and output

can be an AC also. So these are the in

four different circuits that can convert

one form of energy to the other form.

Right? So in this aspect if you see

these are the four major circuits found

in a power electronic subject. Now these

four circuit have their own names. What

are they? If you're going to convert AC

to DC they are called as rectifiers.

If you're going to convert DC input to a

DC output then it is called as a chopper

circuit. If you are going to convert a

DC input to a AC output then it is

called as an inverter. If you're going

to convert a AC input to a AC output

then it is called a cylo converter.

So these are the four major circuit

found in a power electronic subjects. Now

Now

you I can understand a thing anybody can

understand like if your input is AC and

if your application is going to be a

output sorry DC. Now maybe your input is

a AC supply that is EB or something from

there you want to use a load which is

actually working in a DC. So you need to

convert a AC to DC. Similarly, there is

an I can also understand this part that

is maybe your input is DC that is you

may use a battery as an energy source

and accordingly your output uh

load can be like application can be a AC

application. So for that you need to

convert a DC to AC. So you are using an

inverter. Okay fine. when your input is

also take these two cases here if you

see your input is also same and output

is also same. So why I need to convert

same DC to again another DC. Why I want

to convert same AC to another AC?

Take 2 minutes time to answer in your

I'm getting access like fixer voltage to

a control voltage

to make it as a variable AC.

So yeah so I am continuing here. So

if you see here the objective is very

simple maybe your input is varying my

output my output should not vary I need

a constant output or your input is v

constant I need a varying output. So fix

it to variable that is actually a

interesting and short crisp answer for

this question. So if your input is fixed

but I don't want a fixed value as an

output. I want different ranges of

output then I need to convert a one for

one form of energy to a same form of

energy. There is a need for it. So so

for that reason only I'm going to

convert a DC to DC. Similarly a AC to

AC. So if you are going to convert a DC

to DC then it is called as a chopper

circuit. When you are going to convert a

AC to AC that is called as a cylo

converter. For our electric vehicle

application we will be in use of chopper

rectifier and inverter whereas the

application towards cylo converter is

very less and refined.

Uh some more few more answers I'm

getting. Uh

yeah mega j yeah yeah okay to change one

DC voltage level to another while

maintaining stable and efficient. Yeah,

that is the answer I have given correct.

So to match consistence power supply.

Yeah, fix it. Yeah, that is what so

maybe you have you have type typed it by

yourself or from the answer I don't know

but uh you have done a good job. Yeah,

that is the answer like if I want to

have my variable what is my requirement

of my output whether it should be a

fixed or variable based upon that I will

take a call. So to continue with here we

are going to use rectifier chopper and

inverter for an electrical vehicle

system whereas in cylo converters

application is not there in an

electrical vehicle system. So we are

just moving on forward. Yeah first step

we are going to see about these circuits

only that is DC to DC converters. So

they are called as choppers right.

right.

So DC toDC converters convert a fixed DC

input to a variable DC voltage or vice

versa. The DC voltage is controlled by

varying actually the duty cycle. So what

is a duty cycle? We'll go about it. Next

why we need to convert the DC toDC

conversion. These are the three points

that is fixed variable to a variable

value to avoid the huge scale power

devices. For example, if my battery is

of 48 volt, okay, maybe 100 volt or

something. Now, if I want to use a small

equipment, okay, which is of less

operating voltage, say 12 volt or 10

volt, I need not go I can connect it but

ultimately the main power source of from

the battery will be drained because of

this lesser load. Correct? So uh now

what I have to do is that I have to

either go for a separate battery or I I

I have an option like I have to step

down the voltage. So the best option is

stepping down the voltage. Similarly for

a huge operating application I need not

go and invest more amount on building up

a another uh new battery for only that

application. So instead what I can do I

can use a step up chopper and I can add

in in in between it so that it will

boost the voltage and it will give. So

to avoid huge scale power devices what

we can do is we can use a low power

devices itself instead of going in for

huge power. For example if I'm going to

buy an inverter if I matching with my

battery capacity what happens is I need

to go for a higher higher power

inverter. So instead of that what I will

do I will just put a small power

inverter which can operate my motor and

what I will do I'll just add a step down

chopper in between the battery and my

inverter. So this saves the cost as well

as the complexity in the component

level. So to avoid these things only

what we are doing we are in

incorporating this types of variable DC

toDC converters that is called as

shoppers. So finally the unrelated

signal to regulate signal that is the

variable input I told no that can be

considered to be unregulated signal

right because if your input is going to

be continuously varied it can be like

varying uh unregulated signal is not

regulated it is unregulated. So when I

turned it to to make it as a constant

value it is called as a regulated value.

So from unreulated signal I have

converted that to a regulated signal. Okay.

Okay.

So these are few of the applications

where you use uh

DC toDC converter chopper that is

several switch mode power supply that is

SMPS for ECUs in automotive application

like body safety ADAS that is advanced

driver assist systems powertrain in

e-mobility exclusively like automotive

DC toDC converter IC are in high demand

regenerative braking system and to

operate any LED as a display or

emergency lamps with seamless bug boost

regulations and fast dynamic load jump

behavior. Synchronous DCT offer

additional flexibility to high power

applications. So that is what this point

denotes like to avoid huge scale power

devices. Right now with this brief

introduction I'm just going into the circuit.

So just consider this circuit. See this

circuit. It is a very simple circuit,

right? you are going to have a switch

and from there I'm connecting a inductor

and it is connected to a load. So it is

ending up here. Now here I have

connected a diode parall to the load.

Correct? This is a diode. You know the

symbol this is a diode and this is an

inductor and this is a load and this is

a switch. So in the morning session you

have learned about all these components

and you know definitely how this circuit

is going to work. The mode of circuit is

when I going to switch on the circuit

and when I'm going to switch off this

switch what happens.

You may not give the answers but just

check the circuit and just recall

yourself like how these components will

work accordingly. You just bring it into

your mind like when the switch is

getting closed how the current flow will

be there and when the switch is open how

the current flow will be there. So this

is what you're going to spend another 30

seconds for this. Just go through the

circuit analyze within yourself. You

need not comment on the live chat box.

You may just analyze it, follow the

current flow and you can keep it in your

mind so that we will discuss. If you

find any change in your thought process

that means you have not understood the

subject properly or you can correct it.

If your frequency is matching with like

your answer is matching with whatever I

am going to deliver then you have

understood the concept whatever you have

told from model right. Just analyze when

the switch is closed how the current is

going to travel what is going to happen

in the circuit when the switch is open

what is going to happen in the circuit

just I'm giving a time of 40 to 30 seconds

Yes, here I'm ending up the time and I'm

going to now explain about the circuit.

Before that I have a question like what

does variable DC actually means? So

variable DC means if your input is say

for example 30 volt DC your output

requirement may be like 10 volt DC 15

volt DC that is called as actually

variable DC. Your input is constant but

your outputs are different. So that that

variable means different outputs. It is

not like constantly it is varying. It is

like different outputs. Okay. Say for

example, let us take a solar panel as an

example where you can see the radiation

is there. The solar panel is supposed to

give 1 kilowatt output. Maybe because of

the radiation it is varying. Now your

input is also varying. Because of that

the output is varying. Though the input

is varying. If you want to get a

constant output as a voltage you just

use a regulator that is chopper circuit.

Right? So that is the meaning. variable

means it you have a different sets of

output values right I think I have

answered your question I'm moving on to

the circuit now here you see now I'm

just going to switch on the circuit now

so when the circuit is switch on what

happens the load is connected so the

when the load is connected this circuit

is called as a closed circuit if the

load is not connected I have obviously

is I what I will tell it is a open

circuit now the circuit is closed

because the load is connected with two

terminals. When the load is connected

with two terminals, what happens? The my

current is going to start to flow. How

much amount of current will flow? My

load requirement demand. If my load is

demanding for 3 amp, 3 amp of current

only will flow. If my load is requiring

for 10 amp, then it will 10 amp of

current only will flow. Not more than

that. Now, this particular current is

starting to flow. As the switch is on,

the current is going to reach this

point. And I'm sure you know this point.

This point is called as no. Yeah. Now

the node node is coming here. So my

current start to divide. Now my current

is going to come this way. And finds my

diode is reverse bias. Since my diode is

reverse bias. Now my current will not

flow through this line. Instead the

entire current will flow through this

line only. So the total amount of

current will flow this this line only.

Now my inductor is getting charged. My

current is traveling through the loop.

My inductor is getting charged and I my

current is coming here reaching the

load. My load is starting working. That

is let us take an example of bulb. My

bulb is glowing now and the current is

leaving through the negative terminal.

So this is how the circuit is working.

Right now the second mode is when my

switch off that is my switch is

released. So when my switch is released

what happens? My input supply is cut.

Now my inductor is charged. Correct or

not? My inductor is charged. When the

supply is cut in the circuit, what

happens? My inductor will start to

discharge. How the inductor will

discharge? My inductor will discharge by

changing its polarity. So when the

current entered this way, right? It was

positive here and it was negative at

this point. Right? The minor current

traveled here. It traveled through the

loop and it came this way. So this was

positive and this was negative. Correct?

Now my inductor is going to discharge.

When inductor is discharging what

happens? It changes its polarity. Now

this is this will become a positive and

this will become a negative. My inductor

is going to discharge few current. How

the current will flow from positive to

negative through the load. So from this

is going to be positive. This is

negative. So it is coming here. My

current is coming here. My bulb is

starting to blow. After glowing my

current will glow here, come here. Come

here. As the switch is closed. This this

line is actually disconnected. So my

current is coming here. It is just

traveling through the this path. When

this path is there, my diode is forward

bias. Again my current will go this way.

As the switch is closed, my current will

not go this way. So again it will travel

through the inductor. So this will be in

a loop.

Okay. This will be in a loop.

And unless what time? Unless this

inductor is getting discharged. Unless

it is getting discharged, what it is

going? My current will be in a loop. My

load will be constantly receiving a

current and it will slowly slowly slowly

discharge and it will go to the zero.

Before it is going to reach zero, I'll

again switch on this circuit. So what

happens again? My current will flow.

Current will come here. This is reverse

bias. My current will not go that side.

So it will go recharge it and it will

come back. load is getting supply and it

will close. Again I will remove my

switches. My conduct my inductor will be

in discharging in opposite polarity. So

this will become positive. Again this

will be in a loop again before getting

zero. So continuously I will switch on

and switch off my switch. So this is how

this is working. So if I do so what

happens? If I do so what happens is that

this is what it happens. So I am

constantly increasing my uh switching on

and switching off my circuit. So what

happens is my load is getting a RMS wise

it is getting a low voltage. How it is

getting a low voltage? Yes, just check

out this equation. My output wtage

output wtage means wtage across this

load that is given by supply voltage

into T on by T. This t on by t is called

as duty cycle.

This is t. Okay. So t on by t is duty

cycle. So my input is v out is equal v

out will be equal to vs into t on by t.

So by doing so what I am doing is that I

am see let us take an example. Let us

take two water uh one water can. Okay.

which is uh you have a tank and you have

a bucket. Your tank and the bucket is of

same capacity. Okay. Now you are just

turning on the tap. Now the tank is

fully drained at the same time. Your

bucket is full. It is fulling. So when

it is reaching the full let us take it

is taking 40 seconds. Now what you are

doing you are again refilling the tank.

You are now that for in that 40

secondond you are just switching on the

tap for 20 second and you are switching

off it for 20 second. Now the total

amount of work done time taken is 40

second but in this 40 secondond your

tank is not fully drained or your bucket

is not fully filled. It is of 50%age. So

you are reducing the amount of work

done. Okay, 50%age of work only done but

same time 40 second again in the 20

second again 10 10 for each 10 seconds

or 15 seconds you are going on on and

off on and off by doing so what you will

do is the total time you are taking the

total time you are taking is same but

whereas in infrequently you are

switching on and switching off because

of that the amount of work done is low

now when the amount of work done is low

average work done will be less So here

also what you are doing is you are

making the voltage to flow on and off in

different situation at a higher voltage

and lower voltage for the entire

operation the average output wtage you

got will be very less. So this is what

you're going to do correct. So this

equation states that only like based

upon your duty cycle based upon your

duty cycle the amount of voltage can be

increased or decreased based upon your

duty cycle that is how fast you are

turning on and turning off. How at what

sequence you are how much time you are

turning off and turning on you may

change the amount of output wtage you

have achieved. So now you just take this

example VS is 10 volt that is your

supply voltage is 10 volt T on T on is 7

second T off is T on plus T off that is

7 + 3 10. So what would be your V out?

seven. So the outputs are the answer is

coming as seven right

so all are uh texting as 7 volt so I

need not calculated maybe uh you are

good so because of that I'm believing

your answer it is to be 7 volt now your

input wtage was 10 volt you didn't do

anything you just turned on and turn off

the switch only other than that you

didn't do but out at the output you got

a output wtage of 7 volt am I correct so

what you have done your input was high

and your output was less okay this is

called as you're stepping down your

wtage correct now similarly you have so

I think most of you have texted a right

answer and I I'm happy to see that now I

just wanted to trigger your uh

calculative knowledge much more. So I'm

just giving this task also just put your

key on and off at any value. I just

wanted my V out to be greater than your

uh input wtage. That is your vol output

wtage should be more than 10 volt. You

have to mention me in the chat box about

T on second and T of second. Yes, just

One answer is came as not possible. If

somebody is making it possible, I will

be happy. Just mention me.

Repeat the question. Okay. Again, I am

repeating. So in the in my example, I

have given a t on and t of time. If you

substitute in that uh equation, you are

able to get 7 volt as an output. That is

your step down. Supply was 10 volt and

output wtage was 7 volt. Now I just

wanted some other options to be tried

out in T on and T off so that my VS will

be 10 volt and V not will be more than

13 volt if uh t on is 10 second and t

off is 3 seconds. Can anybody verify that?

Somebody claiming it to be a wrong answer.

So I think uh you are trying out very

hard and you are not able to find out

because I got seven as an answer very

fast. Many of you have replied but for

VSSs 10 volt

okay it's not possible sir many oh you

are giving maximum we get 10 volt if

duty cycle is 100%. Okay, good. So, what

you can understand? No, stop there.

Yeah. Okay, fine. Thank you. Many of you

have tried out. Very good. But uh and

you are able to find out we are not able

to go beyond that uh input wtage. Yes,

that is correct. Few good answers are

also coming like duty cycle maximum we

get is 10 volt if the duty cycle is 100%

which cannot that cannot be done because

the duty cycle should be on and off

period right that cannot be done. So I

understand these things. So why we are

not able to do is this is simply a

simple example of a chopper circuit.

Okay, this is a chopper circuit. We are

going to convert a DC to DC. But for

doing higher operations like either a

bringing a small voltage to a higher

voltage, we need to rebuild a circuit

according to our need. So that is what

we want. Okay. In rebuilding means you

don't you need not think like uh we are

going to go in for a complicated circuit

or different components and these things

it is going to be a headache like that.

You need not worry about it. Why?

Because whatever you have studied in the

morning session, those are the

components only available in an

electronics. Other than that, nothing

nothing else is there. Okay? You have to

rearrange the component in that way

only. And you have to operate the switch

in whatever pattern you want to do only.

But so other than that nothing is there.

If I give any circuit any complicated

circuit in the world now you are in a

position to debug it because you know

when a switch is on how the current is

going to flow when the current is going

to switch that particular component how

it will react when it is reacting

accordingly how my graph is going to be

there I'm very sure about it you know

these things so when you know these

things definitely you can crack down any

circuit so just I'm going into deeper

into this chopper circuit so here it is

so this is how a practical homemade that

is our labm made uh buck buck converter

is there here. So here you can see the

type of DC toDC converter. It is divided

into three types. One is buck converter

that naturally step downs your voltage

from the input wtage. The next one is

boost converter which actually steps up

your input to the output. Your output

will be more. And buck boost converter

that is the combination of bug as well

as boost. It can birectionally operate

in both the direction. Either it can

reduce the voltage and give you or it

can increase the voltage and give you.

Right? So this is the simple line

diagram of all the three circuits.

Right? You can find from this circuit

any any new component is there. Right?

Nothing. So

many all are the same components only.

Whatever components you are finding in

this circuit only it is there. Whatever

components you are finding in this

circuit only it is there here also.

Other than that no component is there.

So see about the components whatever you

have studied in the morning class only

it is there other than that no other

component is there. So it is again a

much more easy task for you to study

about these circuits right with this

confidence you just go into this buck

converter. Buck converter was the

converter we just saw right now for

explaining the chopper circuit that is

a switch will be there. From there I

will connect an inductor to the load.

The role of this capacitor is voltage

regulation. They do not have any

predominant role over here. If you have

this or do not have this, no problem.

This actually stabilizes the voltage.

Right? So this actually acts as a filter

or something like that. So it is used

for stabilization purpose only. So you

need not worry about these things. So

just the main components are your switch

diode, inductor and your resistor. So

you saw this mode of operation. One is

mode one is switch on. Switch one is on

and freewheing diode is off because when

the switch is on the role of freewheing

diode is not there because it is reverse

bias. So the role of reverse bi in the

reverse bias the diode will not turn on.

You know that and uh mode two is when

the switch is off now the diode is

forward biased. When the forward bias is

happening the current is going to be in

a loop. So if I do so these are my

output waveforms. My current is going to

be like this.

Whenever the inductor is discharging, my

current is discharging, right? So my

average output wtage will be lesser than

the input wtage. So this thing only we

have studied in the normal operation of

a chopper circuit.

If you see the mathematical approach

over here in both the state I'm going to

apply Kov's voltage law. By applying

Kov's voltage law I I know that when the

I is closed what happens to the voltage

and the duty cycle. And uh using the

sorry using the kit current law in both

the condition like opened state and the

closed state I will understand how what

would be my wtages and the sum of the

voltages uh currents and coming to

finally the sum of the wtages to be zero

that is kov's voltage if I equate with

this equation I'll be getting my output

wtage to be duty cycle into my input

wtage. So using this equation you'll be

able to find it out right what would be

your uh this thing and you have

calculated it and you have seen it also. So

next is the main thing is whenever you

are performing or constructing this type

of chopper the value chosen for inductor

is very very important because the

inductor value calculation is why that

much crucial because because of that

only you can just able to manage like

current current flow to be in a loop

till what period because you are fixing

this duty cycle right your t on and t

off period is decided by So according

when the when the circuit is in T off

period that is when the switch is off at

that time inductor should have the

capability to hold the current till the

other cycle other T on period is coming.

So based upon that you need to calculate

your inductor value in such a way that

your current current uh drop is not

going to reach this point. Instead it

has to maintain in this peak itself. It

will not it should not come to zero. So

that is your main aim. Based upon that

only you should calculate your inductor

value. Right? Next coming to boost

converter. Now what I am doing is I'm

just placing my this is my circuit

arrangement. I'm taking those three

components. I I took the switch from

here and kept here. And from that

inductor I have kept my inductor here. I

kept my diode here. This is my

arrangement I have made. Now again as

you did in the previous chopper circuit

that is buck converter you you just

perfor take some 30 to 40 minutes

analyze this circuit again the mode is

going to be switch is going to on and

switching is going to off. So when the

switch is on what is going to happen and

when the switch is off what is going to

happen right? So this is what you need

to analyze for another 30 to 40 second

and then again I will start explaining

the circuit. If it is matches with your

understanding then you're well and good.

If not just learn from what I'm doing.

Yeah just take some 30 to 40 minutes

So yes, I think you might have gone

through the circuit and you might have

known like when the circuit is on, when

the switch is on, what happens and when

the switch is off, what is going to

happen, right? So first thing I want to

ask a question when I switch on this

circuit when I bring this switch towards

this line I close the circuit what I am

capacitor

manybody everybody's asking about

capacitor capacitor as I said it is used

for voltage stability so the role is

very simple if you remove the capacitor

also it is not going to be an effect

so having a capacitor and not having a

capacitor doesn't make that change in

the working principle.

It is just stabilizing the voltage. So

you need not worry about it.

So it must be there in a boost

converter. So if you want to have a

capacitor in a boost converter well and

good you can have it. No issues. But if

you remove capacitor also that doesn't

make any influence on the performance or

see again I have told no here I have

added a capacitor similarly if you want

to add a capacitor here I am working for

explaining the working principle. So for

a working principle the role of

capacitor is

negligible. So I have just ignored it.

So if you want to have a capacitor

definitely you can have it. If you see

any practical buck or boost converter

capacitor will be there. I'm not telling

capacitor should will be eradicated or

capacitor should not be there. I'm

telling the capacitor will be there for

a working principle explanation

operation. It is not required to have a

circuit in a capacitor inside a circuit.

Okay. So now coming to the question when

I bringing this switch to the closed

position what I am doing actually to the circuit

My question is something different. Very

simple question. When I bring the switch

to the closed question, what I am

actually doing to the circuit? First

tell me that and then you can explain

about the working principle. First tell

me like first point when I switch the

when I make the switch to close what

actually I'm doing to the circuit. You have studied about different types of

have studied about different types of circuit in the morning session right? It

circuit in the morning session right? It should be within that. Just think and

should be within that. Just think and tell me the answer.

It is not closed path. Again I'm telling if a load is connected if the switch is

if a load is connected if the switch is not here then also it is closed path

not here then also it is closed path only because uh

only because uh your battery is connected to the load

your battery is connected to the load and load is closing. If the switch is

and load is closing. If the switch is not there also it is a closed circuit

not there also it is a closed circuit only. So it is closed path.

only. So it is closed path. So one answer I'm getting is short

So one answer I'm getting is short circuit. Is that correct or not?

Not dividing current. I'm not dividing the current there. Am I

I'm not dividing the current there. Am I making a short circuit or not? Just tell

making a short circuit or not? Just tell yes or no in your comment boxes.

Am I creating a short circuit in my circuit by switching on it?

circuit by switching on it? Am I doing a short circuit

Am I doing a short circuit or not?

or not? Yes. One answer. Yes.

What about others? I'm getting no one answer to be no.

I don't want any other answer other than yes or no.

yes or no. Am I creating a short circuit or not?

Am I creating a short circuit or not? Give me one answer. Yes or no? I don't

Give me one answer. Yes or no? I don't want justification.

Krisha, you only said it is short circuit. Now

you only said it is short circuit. Now you are telling no.

you are telling no. Previously I got all the answers to be

Previously I got all the answers to be yes. Yes. Yes. No. Everything is no. No.

yes. Yes. Yes. No. Everything is no. No. No.

What actually you are doing is short circuit? It is yes. The answer is yes

circuit? It is yes. The answer is yes only. Actually you are creating a short

only. Actually you are creating a short circuit only because you are just

circuit only because you are just connecting the positive and negative of

connecting the positive and negative of the battery terminal. Aren't you doing

the battery terminal. Aren't you doing that?

that? You are doing that you are creating a

You are doing that you are creating a short circuit. So since you are getting

short circuit. So since you are getting a creating a short circuit when the

a creating a short circuit when the switch is getting closed what actually

switch is getting closed what actually you are doing? What happens to the

you are doing? What happens to the circuit? What happens to the voltage and

circuit? What happens to the voltage and current

current in a short short circuit? What happens

in a short short circuit? What happens to the voltage and current?

current is maximum and voltage is zero. Yes. So now current is maximum and

Yes. So now current is maximum and voltage is zero. So when the current is

voltage is zero. So when the current is maximum what happens to the inductor?

maximum what happens to the inductor? Aren't you making the inductor to charge

Aren't you making the inductor to charge to its maximum value?

So one this is once this is charged to the maximum value now you are turning it

the maximum value now you are turning it off. Now what happens the voltage is

off. Now what happens the voltage is coming the inductors are charged and it

coming the inductors are charged and it is when this is going to

is when this is going to open inductor start starts to discharge

open inductor start starts to discharge but you are not allowing it to

but you are not allowing it to discharge. Okay so when you are getting

discharge. Okay so when you are getting uh sorry when this switch is on the

uh sorry when this switch is on the inductor will try to discharge correct

inductor will try to discharge correct or not. So but when it tries to

or not. So but when it tries to discharge it you it will not discharge.

discharge it you it will not discharge. Why? Because its input terminal are

Why? Because its input terminal are connected to the voltage

connected to the voltage battery terminal. So what happens is

battery terminal. So what happens is this will draw a current and similarly

this will draw a current and similarly since it is short circuited as a

since it is short circuited as a previous point. This inductor is again

previous point. This inductor is again charged to the maximum value. Now both

charged to the maximum value. Now both will add upon and come here. your diode

will add upon and come here. your diode is forward bias and it will reach the

is forward bias and it will reach the load which actually makes the amount of

load which actually makes the amount of voltage to flow through it to a higher

voltage to flow through it to a higher value. So this is the basic work

value. So this is the basic work principle. Okay. First thing what you

principle. Okay. First thing what you are doing is you are just making the

are doing is you are just making the inductor to charge very fast to its

inductor to charge very fast to its maximum value. After that you are

maximum value. After that you are switching off means your voltage will

switching off means your voltage will get your short circuit is getting

get your short circuit is getting released and your voltage will start

released and your voltage will start current will start to flow through the

current will start to flow through the inductor from the voltage. Now your

inductor from the voltage. Now your voltages uh average wtages will add upon

voltages uh average wtages will add upon each values and it will try to boost the

each values and it will try to boost the regular input wtage value. So this is

regular input wtage value. So this is the basic work principle of your boost

the basic work principle of your boost converter. See here. So the first mode

converter. See here. So the first mode is your switch is on. Now the inductor

is your switch is on. Now the inductor is charged now. The inductor is charged

is charged now. The inductor is charged now and your current is not flowing

now and your current is not flowing through this. Now what happens is you

through this. Now what happens is you are just going to switch off it. When

are just going to switch off it. When you switch off it now from the positive

you switch off it now from the positive the diode is coming to the load and it

the diode is coming to the load and it is going just what you are doing is you

is going just what you are doing is you are making the inductor

your inductor to charge more at this instant. Now the inductor is charged for

instant. Now the inductor is charged for higher higher potential.

higher higher potential. Now when the switch is off obviously if

Now when the switch is off obviously if you disconnect it from this point then

you disconnect it from this point then only the inductor will discharge but

only the inductor will discharge but since it is getting connected and you

since it is getting connected and you are making the path flow to be higher

are making the path flow to be higher here. The voltage also will flow from

here. The voltage also will flow from here and it is not disconnected. So the

here and it is not disconnected. So the voltage also will flow from here. So

voltage also will flow from here. So from this positive to negative the

from this positive to negative the current will flow in this loop only. Now

current will flow in this loop only. Now this makes the inductor to

this makes the inductor to add upon the voltage and give at the

add upon the voltage and give at the base terminal. So this is what actually

base terminal. So this is what actually you are making it to boost the voltage

you are making it to boost the voltage RMS voltage. Right? If you see it in a

RMS voltage. Right? If you see it in a closed path here in a mathematical way

closed path here in a mathematical way see here when the I is closed okay your

see here when the I is closed okay your voltage and inductor will into duty

voltage and inductor will into duty cycle by your time. Now when the switch

cycle by your time. Now when the switch is open now again by applying your K KCL

is open now again by applying your K KCL if you see your output wtage equation

if you see your output wtage equation will be in this way. So applying KVL the

will be in this way. So applying KVL the summation of open and closed state will

summation of open and closed state will be equal to zero. If you equate this

be equal to zero. If you equate this both the value to zero you'll be getting

both the value to zero you'll be getting the final equations to be V by VN will

the final equations to be V by VN will be 1 by 1 minus your duty cycle. Okay.

be 1 by 1 minus your duty cycle. Okay. So in that case if you apply your

So in that case if you apply your voltage and check you can find your

voltage and check you can find your based upon your duty cycle if you vary

based upon your duty cycle if you vary the duty cycle and check you'll be

the duty cycle and check you'll be getting an increased output wtage. Okay

getting an increased output wtage. Okay so this is how your boost boost uh

so this is how your boost boost uh converter will be working that is your

converter will be working that is your step up voltage.

step up voltage. So here also the calculation of your

So here also the calculation of your inductor is very very important. So

inductor is very very important. So based upon your inductor value only what

based upon your inductor value only what you can achieve is that you can get a

you can achieve is that you can get a how much amount of current it can work

how much amount of current it can work to with which time that is depending

to with which time that is depending upon this inductor value. Again I'm

upon this inductor value. Again I'm telling the calculation of this inductor

telling the calculation of this inductor is very very important. So the as you

is very very important. So the as you know once the value of inductor is

know once the value of inductor is connected calculated what you have to do

connected calculated what you have to do is inductor is what a core will be there

is inductor is what a core will be there over that a wind wire will be wounded.

over that a wind wire will be wounded. So based upon the number of turns you

So based upon the number of turns you can increase the inductance value. So

can increase the inductance value. So you can just if time permits in this

you can just if time permits in this session I means in this course of time

session I means in this course of time like for this five days if time permits

like for this five days if time permits we may also have a demo like how to

we may also have a demo like how to check this inverter using any simulation

check this inverter using any simulation tool that thing also we'll be doing it

tool that thing also we'll be doing it right. So choice of inductor is very

right. So choice of inductor is very very important in a case of your bug as

very important in a case of your bug as well as boost converter. Now coming to

well as boost converter. Now coming to bug boost converter. So these are few

bug boost converter. So these are few modules which are available readyly in

modules which are available readyly in market. So

market. So so this could be your circuit over here

so this could be your circuit over here right. So

right. So here you have a switch and in this case

here you have a switch and in this case you are going to connect a inductor in

you are going to connect a inductor in parallel to the load and your input and

parallel to the load and your input and you have a diode over there. So again as

you have a diode over there. So again as you did in the previous two

you did in the previous two circuits in this circuit also what you

circuits in this circuit also what you have to do you have to just switch on

have to do you have to just switch on and switch off your t switches. So there

and switch off your t switches. So there would be two modes one is switch on and

would be two modes one is switch on and one is switch off. So you're going to

one is switch off. So you're going to adjust the duty cycle by actually what

adjust the duty cycle by actually what you're doing by switching on switching

you're doing by switching on switching off is you are adjusting the duty cycle.

off is you are adjusting the duty cycle. Okay. So by uh duty cycle you are

Okay. So by uh duty cycle you are adjusting in certain way that your

adjusting in certain way that your switches will be on for certain time and

switches will be on for certain time and off for certain time. Is that clear? So

off for certain time. Is that clear? So in that mode

so please do slowly because we are non electrical students. Okay. Actually I'm

electrical students. Okay. Actually I'm going slow only according to myself but

going slow only according to myself but again okay I'll take some time to

again okay I'll take some time to explain this circuit also then see here

explain this circuit also then see here this switch now you are going to turn it

this switch now you are going to turn it on and turn it off that is the duty

on and turn it off that is the duty cycle dut you are controlling the

cycle dut you are controlling the circuit by means of duty cycle you are

circuit by means of duty cycle you are you have you don't have any other

you have you don't have any other controlling option because your aim is

controlling option because your aim is to here if some voltage is given here

to here if some voltage is given here you have to get some voltage that is it

you have to get some voltage that is it this voltage voltage is given by the

this voltage voltage is given by the source. This voltage is utilized by the

source. This voltage is utilized by the load that is any application.

load that is any application. Correct? So you have built this circuit.

Correct? So you have built this circuit. You have only option to control over the

You have only option to control over the circuit is on and off period of the

circuit is on and off period of the switches. So that is called on and off

switches. So that is called on and off period of the switches is called as duty

period of the switches is called as duty cycle. The thing which is you are going

cycle. The thing which is you are going to perform by switching on and switching

to perform by switching on and switching off the circuit is called as duty cycle.

off the circuit is called as duty cycle. So whatever you are going to control in

So whatever you are going to control in the circuit it is by means of duty

the circuit it is by means of duty cycle. So through duty cycle you are

cycle. So through duty cycle you are going to switch it on and switch it off.

going to switch it on and switch it off. Right?

Right? So I'm going to analyze the circuit now

So I'm going to analyze the circuit now when the switch is on. So when the

when the switch is on. So when the switch is on what happens this circuit

switch is on what happens this circuit is becoming a closed circuit. When the

is becoming a closed circuit. When the circuit is being closed circuit and the

circuit is being closed circuit and the load is connected my current will start

load is connected my current will start to flow. So my current is flowing from

to flow. So my current is flowing from positive to to negative through load.

positive to to negative through load. Now from positive it is traveling

Now from positive it is traveling through the switch. switch is on now.

through the switch. switch is on now. Now it is coming here. Now inductor is

Now it is coming here. Now inductor is charged. Okay. When I when it it is

charged. Okay. When I when it it is traveling to this part, this part the

traveling to this part, this part the diode is what happening? Diode is

diode is what happening? Diode is reverse bias. When the diode is reverse

reverse bias. When the diode is reverse bias, you all know diode will not turn

bias, you all know diode will not turn on. Now the inductor is getting charged.

on. Now the inductor is getting charged. Totally it will get charged and till

Totally it will get charged and till then the current is not going to the

then the current is not going to the load. Okay, it is getting charged and

load. Okay, it is getting charged and this will stay at this path. Now I am

this will stay at this path. Now I am switching off the circuit. That is I'm

switching off the circuit. That is I'm turning off this circuit off.

When I'm turning off, now what happens? The inductor will change its polarity.

The inductor will change its polarity. Okay. When the current was giving, this

Okay. When the current was giving, this was positive and this was negative.

was positive and this was negative. Correct? Here it is positive and here it

Correct? Here it is positive and here it is negative. Now while discharging this

is negative. Now while discharging this has to become positive and this has to

has to become positive and this has to become negative. So from positive to

become negative. So from positive to negative the current will always travel

negative the current will always travel through the load. So from positive the

through the load. So from positive the inductor is discharging. Now it is going

inductor is discharging. Now it is going to the load and the current is coming

to the load and the current is coming here. It is forward by us and it will

here. It is forward by us and it will close here. And this current will be in

close here. And this current will be in a loop. Okay. This current is going to

a loop. Okay. This current is going to be in a loop unless and until what time?

be in a loop unless and until what time? Unless and until your inductor is

Unless and until your inductor is getting discharged totally to zero

getting discharged totally to zero value. So what we will do before it is

value. So what we will do before it is going to get a zero value we will again

going to get a zero value we will again turn off the switch. So this is how in

turn off the switch. So this is how in all the three switch in all the three

all the three switch in all the three types of choppers the mode of operation

types of choppers the mode of operation will be there. Why the mode of operation

will be there. Why the mode of operation is same in all the type of choppers

is same in all the type of choppers because again I'm repeating the same

because again I'm repeating the same thing. This is a circuit. This circuit

thing. This is a circuit. This circuit you are going to place in between a load

you are going to place in between a load and the supply. You don't have any

and the supply. You don't have any freedom of changing in input or an

freedom of changing in input or an output. You can change everything. You

output. You can change everything. You can play and you can change everything

can play and you can change everything within the circuit what you have built.

within the circuit what you have built. This is this is the circuit which I have

This is this is the circuit which I have built. This input I have not built and

built. This input I have not built and this load I have not built. I am talking

this load I have not built. I am talking about practical scenario. In a practical

about practical scenario. In a practical scenario, battery will be there. You'll

scenario, battery will be there. You'll be having any application like fan or

be having any application like fan or light or any uh infotainment or any

light or any uh infotainment or any any other application air condition or

any other application air condition or anything. So you are going to place your

anything. So you are going to place your buck to boost converter in between

buck to boost converter in between battery and this load. This load is also

battery and this load. This load is also not decided by you. This voltage input

not decided by you. This voltage input is also not decided by you. But your

is also not decided by you. But your task is you need to match this wtage.

task is you need to match this wtage. You have to take some voltage from this

You have to take some voltage from this side and you have to give to this side

side and you have to give to this side by means of adjusting your circuit

by means of adjusting your circuit parameter only. What is the parameter

parameter only. What is the parameter which I can change in my circuit is that

which I can change in my circuit is that only the duty cycle of the switch. The

only the duty cycle of the switch. The duty cycle of the switch means what? The

duty cycle of the switch means what? The turn on and turn off period of my

turn on and turn off period of my switch. So by doing that what happens?

switch. So by doing that what happens? First I am analyzing it. So I have I

First I am analyzing it. So I have I have analyzed when the switch is off.

have analyzed when the switch is off. When the switch is off nothing is going

When the switch is off nothing is going to happen. So I'm going to now switch on

to happen. So I'm going to now switch on it. Now I'm switch oning it. When I

it. Now I'm switch oning it. When I switch on it, the current is coming

switch on it, the current is coming here. This diode is reverse bias. The

here. This diode is reverse bias. The entire current will go through this path

entire current will go through this path only. So the inductor is getting charged

only. So the inductor is getting charged and this will be in a charging mode. Now

and this will be in a charging mode. Now when I turn the switch off, what

when I turn the switch off, what happens? My inductor is getting

happens? My inductor is getting discharged in the opposite polarity. So

discharged in the opposite polarity. So my current direction will be in this go

my current direction will be in this go to the load and it will through the

to the load and it will through the diode. It will again close in a loop and

diode. It will again close in a loop and it will be in a loop.

it will be in a loop. So before this inductor is totally

So before this inductor is totally drained out and your current value is

drained out and your current value is becoming totally zero, I will again

becoming totally zero, I will again switch on the circuit and make the

switch on the circuit and make the inductor to charge. So this I'll be

inductor to charge. So this I'll be continuously repeating. By doing that,

continuously repeating. By doing that, what happens to the output wtage? This

what happens to the output wtage? This is what we are going to check. Now

is what we are going to check. Now this was my mode. So when my switch is

this was my mode. So when my switch is on and my switch is off, whatever I had

on and my switch is off, whatever I had told I just represented in a

told I just represented in a diagrammatic way.

diagrammatic way. So when the circuit is off I and on I

So when the circuit is off I and on I get this equation that is my output

get this equation that is my output wtage by input wtage is minus duty cycle

wtage by input wtage is minus duty cycle by divided by 1 minus duty cycle. Okay.

by divided by 1 minus duty cycle. Okay. So

so this is my output equation. from this output equation if I derive my output

output equation if I derive my output input uh with respect to input wtage

input uh with respect to input wtage I'll be getting certain values so how it

I'll be getting certain values so how it is going to operate that is what we are

is going to operate that is what we are going to study now so in this how you

going to study now so in this how you are operating how I can operate it buck

are operating how I can operate it buck as well as boost if you see the output

as well as boost if you see the output wtage itself you'll be understanding it

wtage itself you'll be understanding it is actually the

is actually the uh combination of your buck as well as

uh combination of your buck as well as boost right so previously it was d into

boost right so previously it was d into vin for buck and 1 - 1 by D for V out

vin for buck and 1 - 1 by D for V out for a boost converter. So now it is a

for a boost converter. So now it is a combination of both. So in this case

combination of both. So in this case only simple thing what you have to

only simple thing what you have to remember is that we know that duty cycle

remember is that we know that duty cycle always varies from because you you found

always varies from because you you found it right? You found it. Okay. So you

it right? You found it. Okay. So you have concluded like through the duty

have concluded like through the duty cycle only you will be able you are you

cycle only you will be able you are you will be able to reduce the voltage in

will be able to reduce the voltage in the first very first chopper circuit.

the first very first chopper circuit. You concluded like through duty cycle

You concluded like through duty cycle you are you you will be able to adjust

you are you you will be able to adjust the voltage range correct then you you

the voltage range correct then you you yourself concluded another point that is

yourself concluded another point that is I cannot go duty cycle more than one

I cannot go duty cycle more than one because I need to get t on by t off okay

because I need to get t on by t off okay so t I should have t on period also and

so t I should have t on period also and I should have t period also in that case

I should have t period also in that case what I should have I uh if my t on

what I should have I uh if my t on period itself is existing or t of period

period itself is existing or t of period itself existing then only I'll be

itself existing then only I'll be getting an option of more than one. So

getting an option of more than one. So in that case I'm just I we we concluded

in that case I'm just I we we concluded like your duty cycle will be 0 to 1.

like your duty cycle will be 0 to 1. Correct. In this particular circuit if

Correct. In this particular circuit if you are maintaining your duty cycle from

you are maintaining your duty cycle from 0 to 50% that is 0 to.5 value. If your

0 to 50% that is 0 to.5 value. If your DD cycle is 0.5 okay 0 to 0.5 then your

DD cycle is 0.5 okay 0 to 0.5 then your output wtage is larger than your input

output wtage is larger than your input wtage that is your output wtage is huger

wtage that is your output wtage is huger and input wtage is lesser that is you

and input wtage is lesser that is you are boosting if your duty cycle is less

are boosting if your duty cycle is less than 0.05 05 that is 0.5 to 0. Here it

than 0.05 05 that is 0.5 to 0. Here it is 0.5 to 1 and here it is 0 to 0.5. If

is 0.5 to 1 and here it is 0 to 0.5. If it is there then your input wtage is

it is there then your input wtage is small sorry your output wtage is smaller

small sorry your output wtage is smaller than your input wtage that means you are

than your input wtage that means you are step downing. To sum up this point if

step downing. To sum up this point if your duty cycle is 0 to.5 0 to 50%age

your duty cycle is 0 to.5 0 to 50%age then this will behave as a buck

then this will behave as a buck converter. If your duty cycle is 0.5 to

converter. If your duty cycle is 0.5 to 1 then this is called as this will

1 then this is called as this will behave as boost converter. So in this

behave as boost converter. So in this one circuit you will be able to operate

one circuit you will be able to operate either a buck converter or a boost

either a buck converter or a boost converter based upon your duty cycle.

converter based upon your duty cycle. Is that clear?

So this is where we are ending about the chopper. Chopper means what? you'll be

chopper. Chopper means what? you'll be able to convert DC circuit to a fixed DC

able to convert DC circuit to a fixed DC value to a variable DC value or variable

value to a variable DC value or variable DC value to a fixed decision

DC value to a fixed decision is made. So are are you understanding

is made. So are are you understanding the concept of chopper here?

Yeah, cut converter is also acting on the both right but I am what I am trying

the both right but I am what I am trying to convey through this slides or I

to convey through this slides or I cannot go with different types of

cannot go with different types of converters. Okay. I can I I I we we have

converters. Okay. I can I I I we we have different types of uh with switching

different types of uh with switching arrangement to achieve this uh cir to be

arrangement to achieve this uh cir to be very frank nowadays we are not going to

very frank nowadays we are not going to use this sort of circuit also because we

use this sort of circuit also because we are having one circuit from that circuit

are having one circuit from that circuit we are we will be able to switch on and

we are we will be able to switch on and switch off different types of control

switch off different types of control modules through our programs. We will be

modules through our programs. We will be able to access different types of uh

able to access different types of uh circuit component from different

circuit component from different circuit. uh that is if I making a entire

circuit. uh that is if I making a entire circuit board and from there I'm just

circuit board and from there I'm just going to control that circuit board I'm

going to control that circuit board I'm going to utilize for a buck converter

going to utilize for a buck converter means I can do that from that circuit if

means I can do that from that circuit if I want to make it as a rectifier means I

I want to make it as a rectifier means I can do that that I can do by means of my

can do that that I can do by means of my processing processes through my

processing processes through my programming through my switch on and

programming through my switch on and switch off technique I can operate the

switch off technique I can operate the same circuit in different way okay so in

same circuit in different way okay so in that case here what I'm trying to do is

that case here what I'm trying to do is that I'm not trying to show because in

that I'm not trying to show because in your exam examination point of view or

your exam examination point of view or academic point of view. You may study

academic point of view. You may study about different types of converters

about different types of converters right but we are not worried about that

right but we are not worried about that in practical scenario what it is we are

in practical scenario what it is we are need to understand the principle that is

need to understand the principle that is what our aim so so I am resting it to

what our aim so so I am resting it to restricting it to bug as well as boost

restricting it to bug as well as boost whatever converter you're going to use

whatever converter you're going to use you are just going to do one thing only

you are just going to do one thing only you are going to transmit the DC power

you are going to transmit the DC power from battery to other components for

from battery to other components for transmitting it either you are going to

transmitting it either you are going to use a buck converter sorry you are going

use a buck converter sorry you are going to operate the converter in a buck mode

to operate the converter in a buck mode or boost mode that is you're going to

or boost mode that is you're going to step up the voltage or step down the

step up the voltage or step down the voltage according to your application.

voltage according to your application. So there there by themsel there there

So there there by themsel there there only I'm concluding my point. So I you

only I'm concluding my point. So I you I'm just explaining the principle of how

I'm just explaining the principle of how this is happening to be a step up and

this is happening to be a step up and step down thing. I'm not worried about

step down thing. I'm not worried about different types of thing.

different types of thing. So that's why I have chosen these

So that's why I have chosen these things.

So I found few comments like uh today's stuff is more heavy so please try to

stuff is more heavy so please try to conclude it. Is that in the same way for

conclude it. Is that in the same way for others also?

others also? If it is for others also it is in the

If it is for others also it is in the same way then I will try to conclude

same way then I will try to conclude here. We may discuss some general points

here. We may discuss some general points and we may conclude it.

If you want to go forward then I can go with rectifier and inverter today.

Can you plan please share your uh departments? I see like different uh you

departments? I see like different uh you are from non-elect electrical also. So

are from non-elect electrical also. So can you get some can I get some

can you get some can I get some information about your department?

EC mechanical

Easy. Okay. I understand you are from different uh branches.

different uh branches. So

according to me if uh if I conclude here uh will that be okay

if I conclude here uh will that be okay because uh still I think I have a half

because uh still I think I have a half not of time.

Okay I think majority majority students are asking uh me to conclude over here.

Okay. Till here I think uh I'm getting some

Okay. So I I think like uh some relevant points sensible points are there. If you

points sensible points are there. If you cover less topic it will be helpful for

cover less topic it will be helpful for us to understand.

us to understand. Okay. I will take it in a positive note.

Okay. I will take it in a positive note. Okay then fine. I think we will

Okay then fine. I think we will conclude. Shall I conclude now

Okay. What I understand is that uh till 4 p.m. few peoples are

really interested to go through it. So maybe what I can do is that if those who

maybe what I can do is that if those who are really interested to for this class

are really interested to for this class you may

you may go in for shoot out few questions I may

go in for shoot out few questions I may answer for it. Maybe maybe we can have

answer for it. Maybe maybe we can have that sort of a session for another 10 to

that sort of a session for another 10 to 15 minutes and then we'll end up just

15 minutes and then we'll end up just shoot your questions whatever you want

shoot your questions whatever you want to ask to me I will just answer for the

to ask to me I will just answer for the questions

see again PPT sharing uh that academy will be doing for you I am ready to

will be doing for you I am ready to share to them okay

My name is Karun Silva. I have told already

here I have concluded technically if you want to ask any question you may just

want to ask any question you may just ask shoot up few questions regarding the

ask shoot up few questions regarding the subject or anything else

DC to DC converter in simple way what we can keep in mind sir

can keep in mind sir I'm not getting your question in the

I'm not getting your question in the right way but uh I'll just take it in

right way but uh I'll just take it in this way. I am understanding in a way.

this way. I am understanding in a way. I'll just go in a flow. What you maybe

I'll just go in a flow. What you maybe your question is

your question is simple or DC to DC converter what and

simple or DC to DC converter what and all I should keep it in in my mind.

all I should keep it in in my mind. Maybe I will take it in this this way.

Maybe I will take it in this this way. Few points I can uh shoot out like that.

Few points I can uh shoot out like that. So you are if you are going to have a DC

So you are if you are going to have a DC toDC converter the common name used for

toDC converter the common name used for DC toDC converter is chopper. You may

DC toDC converter is chopper. You may you have to keep that in mind and your

you have to keep that in mind and your duty your uh DC converters the choppers

duty your uh DC converters the choppers are controlled through duty cycle. Duty

are controlled through duty cycle. Duty cycle is a diff important terminology.

cycle is a diff important terminology. So duty cycle is nothing but t on by t

So duty cycle is nothing but t on by t total time that is t on by t on plus t

total time that is t on by t on plus t off that is the total on time divided by

off that is the total on time divided by total time period of on plus off. Okay.

total time period of on plus off. Okay. So that is actually the duty cycle.

So that is actually the duty cycle. Based upon the duty cycle only you'll be

Based upon the duty cycle only you'll be able to get how much amount of step down

able to get how much amount of step down percentage or step up percentage you can

percentage or step up percentage you can make. Okay. So based upon the duty cycle

make. Okay. So based upon the duty cycle only you can come to a conclusion like

only you can come to a conclusion like for if my voltage is 10 volt if I'm

for if my voltage is 10 volt if I'm going to make it as 8 volt or 4 volt or

going to make it as 8 volt or 4 volt or 6 volt in a case of step down. Similarly

6 volt in a case of step down. Similarly if it is 10 volt I making going to make

if it is 10 volt I making going to make it as 12 volt or 14 volt 16 volt that is

it as 12 volt or 14 volt 16 volt that is dependent upon the duty cycle both in

dependent upon the duty cycle both in the step up and step down buck as well

the step up and step down buck as well as boost. Okay but if you take the

as boost. Okay but if you take the current current waveform current should

current current waveform current should not go zero. Okay current should not go

not go zero. Okay current should not go to zero because if current is going to

to zero because if current is going to zero your application will switch off.

zero your application will switch off. So we should not make the current to go

So we should not make the current to go to zero for because I am going to switch

to zero for because I am going to switch off my voltage at that time. My current

off my voltage at that time. My current should not go to zero. I my ultimate is

should not go to zero. I my ultimate is making the voltage to go go zero. I

making the voltage to go go zero. I should not make the current to zero. For

should not make the current to zero. For that only what I'm doing I am utilizing

that only what I'm doing I am utilizing a inductor there. So when I utilize an

a inductor there. So when I utilize an inductor there my inductor is taking

inductor there my inductor is taking care of giving the necessary current to

care of giving the necessary current to the load. So when my inductor is giving

the load. So when my inductor is giving necessary current to my load, my load is

necessary current to my load, my load is not turning off but I am switching by

not turning off but I am switching by making the open circuit I making the

making the open circuit I making the voltage to become zero. So when the

voltage to become zero. So when the voltage is becoming zero, my average

voltage is becoming zero, my average voltage if I calculate it is becoming

voltage if I calculate it is becoming less or more. So this is what I am

less or more. So this is what I am doing. So somebody was know capacitor

doing. So somebody was know capacitor should be there should not be there. See

should be there should not be there. See again I'm telling capacitor is choice of

again I'm telling capacitor is choice of yours. If you see a practical chopper

yours. If you see a practical chopper capacitors will be there but for a

capacitors will be there but for a working principle the role of capacitor

working principle the role of capacitor is not there because the role of

is not there because the role of capacitor is to stabilize the voltage.

capacitor is to stabilize the voltage. Okay. So I am here to explain about how

Okay. So I am here to explain about how the system works. For the system works

the system works. For the system works if you see in the equations also there

if you see in the equations also there will not be any equation related to

will not be any equation related to capacitors.

capacitors. It will be related to inductor only.

It will be related to inductor only. Role of inductor will not be in equation

Role of inductor will not be in equation because working principle does not

because working principle does not depend upon capacitor. Capacitor is

depend upon capacitor. Capacitor is nothing but it has it will be regulating

nothing but it has it will be regulating the voltage but for working we are

the voltage but for working we are concentrating on providing the current

concentrating on providing the current to the load that is done by inductor. So

to the load that is done by inductor. So the importance of inductor is there but

the importance of inductor is there but the importance of capacitor is reduced

the importance of capacitor is reduced there. So choice of duty cycle the

there. So choice of duty cycle the important points in chopper is choice of

important points in chopper is choice of switch that is duty cycle and choice of

switch that is duty cycle and choice of inductor and where you place that

inductor and where you place that inductor and the common name is chopper

inductor and the common name is chopper and duty cycle ratio when the duty cycle

and duty cycle ratio when the duty cycle is 0 to 50% it should be in bug 50 to 1%

is 0 to 50% it should be in bug 50 to 1% it will be in boost. So these are the

it will be in boost. So these are the key points that you has to remember uh

key points that you has to remember uh with regard to DC toDC converter and

with regard to DC toDC converter and then uh

then uh we can use stepper motor to control

we can use stepper motor to control firing angle. No to control stepper

firing angle. No to control stepper motor by using firing angle you can do

motor by using firing angle you can do that. Okay.

uh thank you for simple actually my my explanations are simple only I am

explanations are simple only I am actually explaining conceptually only if

actually explaining conceptually only if I go into technical part the other

I go into technical part the other department domain students will get

department domain students will get irritated so I'm just going in an

irritated so I'm just going in an application oriented way and

application oriented way and conceptually

conceptually okay so it is conceptually I'm

okay so it is conceptually I'm explaining it so that even the subject

explaining it so that even the subject handling even the students who are

handling even the students who are familiar to this the way of expl my

familiar to this the way of expl my explanation is something related to

explanation is something related to application way and conceptual way. So

application way and conceptual way. So they will also understand in a different

they will also understand in a different aspect. So my aim is that only. So

aspect. So my aim is that only. So actually this session is planned till a

actually this session is planned till a practical oriented way also. Uh there is

practical oriented way also. Uh there is a demonstration of these type of

a demonstration of these type of circuits in MATLAB simulation. How you

circuits in MATLAB simulation. How you can vary the value and how you can just

can vary the value and how you can just interestingly create a circuit. these

interestingly create a circuit. these things we are planning to do it but as

things we are planning to do it but as the session is going on right if you are

the session is going on right if you are not asking me to conclude uh much

not asking me to conclude uh much earlier I will still go on with further

earlier I will still go on with further demonstrations so you should also

demonstrations so you should also understand those points

understand those points so if you are just asking me to conclude

so if you are just asking me to conclude what I will do is I'll just make the

what I will do is I'll just make the content to be much more uh smaller

content to be much more uh smaller content

content right so but I can understand your point

right so but I can understand your point also if I go in for more uh this thing

also if I go in for more uh this thing uh technically

uh technically deeper and more content in a single day.

deeper and more content in a single day. For grasping it will be more difficult.

For grasping it will be more difficult. I understand that. But uh maybe uh you

I understand that. But uh maybe uh you can just try it out. You can check it

can just try it out. You can check it out. Maybe from tomorrow we you may be

out. Maybe from tomorrow we you may be prepared mentally like you can learn

prepared mentally like you can learn more or something else so that we can

more or something else so that we can from tomorrow you will be having some

from tomorrow you will be having some brainstorming sessions and uh hands-on

brainstorming sessions and uh hands-on like demo sessions. Maybe you will be

like demo sessions. Maybe you will be interested on that. Maybe you may learn

interested on that. Maybe you may learn more. This session was an basically

more. This session was an basically introductory plus technical session. So

introductory plus technical session. So it took theoretically from tomorrow we

it took theoretically from tomorrow we will be having some demo sessions.

So I kindly request everybody to be present tomorrow on time. First point

present tomorrow on time. First point and the next point is be prepared that

and the next point is be prepared that your session is going to be for 2 hours

your session is going to be for 2 hours for sure. Is that clear?

So I think few questions were asked and I have

few questions were asked and I have answered for the questions. So tomorrow

answered for the questions. So tomorrow you are going to see about rectifiers

you are going to see about rectifiers and inverters continuing with the demo

and inverters continuing with the demo of those rectifiers and inverters. Is

of those rectifiers and inverters. Is that clear? So when that is being done

that clear? So when that is being done we will go in for motors

we will go in for motors and uh finally we will conclude it with

and uh finally we will conclude it with embedded system programming and coding.

embedded system programming and coding. So this is our plan as I said in the

So this is our plan as I said in the morning itself. So again I'm repeating

morning itself. So again I'm repeating the same thing be on time and don't

the same thing be on time and don't insist me to conclude earlier instead be

insist me to conclude earlier instead be prepared like you are being comfortable

prepared like you are being comfortable for 2 hours of session.

Thank you. Bye. We'll meet tomorrow. Thank you. Bye.

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YouTube Transcript:Embedded Systems and Design & Development - Feb 23, 2026 | Afternoon | VisionAstraa EV Academy