hello everyone, welcome back to sun innovative YouTube channel. and we are back with the

new video on multiple carrier PWM techniques for multilevel inverters. so before starting

this video i would like to tell you something about the multilevel inverter see when we

are going to design the multilevel inverter so as we know that we need to use more than

6 switches either in MOSFET or IGBT so it is a very much difficult to design PWM pulses

for the inverter and to design the PWM intervals for the output like 5 level, 7 level or the

9 level inverter so here we have some design and we have some techniques regarding PWM

techniques so we will discuss about this techniques and we will go for the simulation. so lets

start this video so here is block diagram of the PWM technique so in which you can see

the multiple carrier are used to design PWM at the different level of output inverter and

a if we combine all the PWM generated pulses in one segment so it will be output voltage

in a PWM sine output voltage. and this is all about the techniques which we are going

to discuss about in this video. so now start with the phase disposition (PD) technique

so it is a PWM in which we need to take X-Y graph here so one carrier waveform is taken

here and the second carrier waveform is taken like this way in which you can see the upper

on X axis above on X axis the phase is 0 degree on below X axis same phase because there is

no phase shifting between the two carrier signal and when we are going to talk about

level so there is equation for the phase disposition technique so that equation is when you are

going to design for 5 level inverter so equation is (N-1) so N is level of output voltage if

you put (5-1) will = 4, so it means the 4 carrier signal you will be required to design

the PWM technique but here there is only two level so there is we can generate output pulses

for 3 level inverter because we have used the two carrier signals like this if you use

the equation (N-1) so it will be a three level inverter (3-1) = 2 so 2 different carrier

frequency is used if you are comparing sinusoidal signal with the carrier signal so you can

see there is a according to frequency of sinusoidal generate the pulses as you can see in a bottom

of PWM pulses are shown here. and a same way you can see the different frequency here two

more level are used here so you can see here the 1 2 3 and 4 carrier signals are used so

ultimately you wanted to calculate the level of inverter so its 5 level inverter because

(N-1) equal to 4 so that's why the 4 levels are used for carrier signals and will be 5

level inverter also see and verify output level 1 2 3 4 and the 5. so like this way

you can generate the PWM pulses for phase disposition system. and now move to again

the equation i have written here you can see this is all about the phase disposition techniques

now move to next method that is a phase opposition disposition so in which as usual we are going

to calculate for the 5 level inverter so same equation we can follow as we have discussed

in a phase disposition system so now same PWM pulses carrier signal are use on a above

x axis and 180 degree shifted carrier waveform are used to design phase opposition disposition

because you can see above x axis the different phase angle and below x axis there is 180

degree phase shifting gate pulse, that's why i have also used the different color for the

identification of carrier signals so by this way you can generate the phase opposition disposition

POD PWM technique and after comparing the sinusoidal waveform you will get the PWM gate pulse.

so don't worry about the all techniques today we are going to discuss about the ultimate;ly

after this video i am going to discuss about the comparison of all techniques and the

what are the advantages having in PD POD and APOD different PWM techniques are there but

we need to also look in part that how it is used and where it is used. now move to the

next method that is the alternate phase opposition disposition technique so in which you can

see the 4 different layers are used for generating carrier signal so in which a if you talk about

the first level 1 part so it is having 0 degree phase shifting and once again level 2 is having

180 degree shifting and one more time 0 degree and once again 180 degree shifting carrier

is used so if you are generating this type of carrier signal to generate the PWM pulses

so that method is called APOD now move to next method that is a carrier overlapping PWM

technique so in which you can see in a graph the carrier signals are overlapping with each

other overlapping means the magnitude offered by the level one carrier signal it will be

a intersect with each other intersect doesn't mean cross the signal it means the middle

part of first carrier signal is the peak value for the second carrier signal that's why it

is called the overlapping so magnitude of 1 signal and the 2 signal and many other signals

are overlapping with each other so this technique popular in generating PWM pulse for multilevel

inverter so there is so many advantages are also there because where you required the

selective harmonic technique for the output inverter to get the eliminate the third harmonic

or fifth harmonic like wise this technique mostly used in a inverter and this is the

variable frequency carrier VFC PWM technique in which you can see two signals are used

as a carrier signal and the both signals having different frequency like upper signals green

one having more frequency and blue signals is having low frequency as you can see in

a graph also and by comparing the sinusoidal signal with this type of technique so you

will be also get the gate pulse for the PWM technique now move to the switching frequency

optimal SFO PWM technique in which you can see the gate signals are used here it is a

alternate phase opposition disposition technique because APOD carrier is used and there is

little change in sinusoidal signal it is like M - W type signal because if you see detail

in the curve that it is look like M - W type so whenever you wanted to operate in a over

modulation technique like when your inverte is having maximum reference signal magnitude

then carrier that time over modulation is happen with inverter so that time if you wanted

to operate your inverter in a 0.8 or point 8 modulation index so that time you can use

this type of technique to get the maximum power or maximum voltage output at the inverter.

and once again this is a different approach like carrier overlapping with the phase disposition

technique it is called CO-PD PWM technique and in which you can see the above X axis

there is a phase disposition it means the whatever the phase angle of carrier signal

the same we are going to use in a below x axis that's why it is called phase disposition

technique with the carrier overlapping technique because here we are doing the multiplication

of both thing like phase disposition and the carrier overlapping so this is also having

some advantage in a different PWM technique and the this is the carrier overlapping phase

opposition and disposition technique so here you can see the above x axis there is different

0 degree phase difference and below you can see the 180 degree phase different is there

and by comparing the sinosoidal signal you will get gate pulse for the inverter and this

is the one another technique carrier overlapping technique with APOD so in which you can see

the overlapping are in the intersecting of the signal you can see in the level of inverter

here so 2 and more than 2 three carrier signal are going to use for intersect with each other

so that's why its is called carrier overlapping with APOD technique so these are the table

which i have prepared for this because after applying this gate pulse to multilevel inverter

so we found that this are the THD level we got 3 level to 9 level inverter so this is

the change we have observed from the PWM techniques when the gate pulse is generated and given

to the inverter so now it is time to get the simulation file so now we are going to use

the MATLAB simulation software to generate and see the how gate pulse is going to generate

in this techniques so lets start the simulation ok now this is the simulation of MATLAB and

PD& POD technique i already developed in MATALAB in this simulation software so i am going

to give introduction regarding PWM technique in MATLAB so actually that depend upon the

type of multilevel inverter that you are gong to use like cascaded H-bridge is there or

a flying diode is there and the NPC invrter is there so that depend on how many mosfet

you are going to use in your inverter and the how many pulse you wanted from the PWM techniques

so basically i given one equation that suppose there is a equation like (N-1) so this equation

wil show you that how to use number of gate pulse from the PWM technique so here is (N-1)

that is the N is level of inverter so if i am going to work for the 5 level inverter

so there is a equation (N-1) so i need to provide the N = 5 so i will be get the (5-1)

equal to 4 so answer is 4 here so ultimately i need a 4 different type of levels carrier

signals in this PWM technique to get the different 5 level pulses inverter and the generate the

5 level output voltage, so here is a answer ultimately i found that if i am wanted to

develop the 5 level inverter so i will be required 4 different type of carrier signal to design

the gate pulse so here you can see this is the sorry i need to remove this so here it

is see here the 4 different type of carrier signal i have use here and once again this

4 different type of here and the only one reference signal i have used here as a sinusoidal

signal here and a this is not gate i have used so ultimately you have two different

pulses like i can also get the pulse from here and like this way suppose if i remove

this so i can get pulse from here and also i can get the pulse from here. so it is complimentary

switching means i can connect this one of the MOSFET and another one like this way i

have used 4 different channels so i can prove the gate pulse for 4 different type of MOSFET

so you can see in a screen also i am going to show you that the how you can use this

gate PWM signal to the multilevel inverter so you can see in the diagram there is 8 MOSFETs

are used so you can give this gate pulse to 8 mosfet and generate the multilevel output

so now lets move to another technique that is POD PWM technique so same way i have used

the 4 different carrier signal and the reference signal so let me show you different values

which i have selected for this, so this is the different values so let me open this and

this one same, and i have divided by the 1000 values so it shows the frequency of a output

carrier signal so 1000 it means 1 kHz, and same value you need to provide in each block

which you are going to use design for and by using this technique you can give the offset

value so that you can design the above the x axis carrier signal and below X axis so

it is called offset values and a same way the values for this signals i have used here and

here also so there is a little change in phase opposition dispossession because as i

told you in and also show you in a presentation that above x axis same phase angle and below

x axis same shifting so it will call as phase disposition and if you are selecting above

x axis as 0 phase shifting and below as 180 degree of it will technique is called POD

technique so now i am going to run this simulation to show you results so let me run this simulation

now it is done here so let me zoom this signal so you can see here the sinusoidal it is the

reference signal and all green lines are carrier signals and you can see and you can check

all the values are in a phase so this technique name is phase disposition because all signals

having the same phase angle without changing any phase that's why this know as PD PWM and

let me open this scope so this is another method that is POD method so in which you can

see carrier and reference signal here and zoom this signal so you can see the above

x axis there is change or there is zero phase degree and below x axis you can see there

is 180 degree phase shifting so you can see this border line and above x axis and below

x axis so that's why this name given as POD technique because all carrier signals are

change on above and below X axis so by this way you can generate the PWM technique in

a matab simulation software so thank you guys suppose if you like this video and a

if you write the comment like you wanted to see this video in next level like apply the

gate pulse to multilevel inverter to show the output results so please guys you share

your comment and ideas in comment box so that i can develop the matlab simulation and to

show you the results thank you guys thank you very much.