IGBT BASED 180 DEGREE CONDUCTION MODE VSI

Detailed design of IGBT-based VSI inverter with 180-degree conduction mode technique.

Switching logic for 180 degree conduction Mode for VSI

In this circuit we have 6 mosfets and we group it into positive and negative group

Positive Group are S1 S3 S5

Negative Group are S4 S6 S2

Three Legs

Leg1 Leg2 Leg3

S1 S3 S5

S4 S6 S2

Note: Two switch of same leg shoud not conduct thats why we use NOT gate

Switching logic for 180 degree conduction Mode for VSI

180 degree means out of full cycle(360 degree T=50 Sec) each switch will conduct for 180 degree,

which is nothing but it will conducts for every half period(180 degreeT/2= 25 sec).

Therefore duty cycle is 50 percentage which i substitute in the pulse generator.

T=1/50= 20msec

m=milli=0.001=10^(-3)=E-03

Delay Calculation for pulse generator

Pulse generator 1 starts from zero

Xdelay1=0 sec

Pulse generator 2 starts from

360 degree= 20msec

60 degree=x=xdelay2

xdelay2=(60*20*0.001)/(360)=3.3333*10^(-3)=3.3333*E-03= Which i substitute in pulse generator two

Xdelay2=3.3333*E-03sec

360 degree= 20msec

120 degree=x=xdelay3

xdelay3=(120*20*0.001)/(360)=6.666*10^(-3)=6.666E-03= Which i substitute in pulse generator three

xdelay3=6.666E-03

Opertion mode

At every instant three switch will conduct for 60 degree= 360/6 switch= 60 degree

mode1: S1 S6 S5 mode conducts for 60 degree 0 degree<wt<60 degree

0sec<t< 3.333msec

mode2:S1 S6 S2 mode conducts for 60 degree from 60 degree<wt<120 degree

3.333msec<t< 6.666msec

mode3:S1 S3 S2 mode conducts for 60 degree from 120 degree<wt<180 degree

6.666msec<t< 10msec

mode4:S4 S3 S2 mode conducts for 60 degree from 180 degree<wt<240 degree

10msec<t< 13.333msec

mode4:S4 S3 S5 mode conducts for 60 degree from 240 degree<wt<300 degree

13.333msec<t< 16.666msec

mode6:S4 S6 S5 mode conducts for 60 degree from 300 degree<wt<360 degree

16.666msec<t< 20msec

From Mode 1 to Mode 3 common switch is S1 will conduct for 60 degree+60 degree+60 degree= 180 degree ,hence the name 180 degree conduction mode.