SHANTILAL SHAH ENGINEERING COLLEGE BHAVNAGAR

DEPARMENT OF ELECTRICAL ENGINEERING

ACADEMIC YEAR 2015-16

POWER ELECTRONICS-II

3-Phase Inverter 180 degree conduction mode

S.NO NAME ENROLLMENT 1 SUDHIR SINGH 130430109052 2 BHAVIN PATEL 130430109039 3 SAMIR DABHI 130430109011

Faculty: PROF.J.K.CHAVDA

dc

LOAD

3-Phase Inverter Circuit

180 degree conduction mode This is a controlling scheme for 3-phase inverter. Each switch conduct for period of 180 degree. Switches are triggered in sequence of their numbers with an interval of 60 .⁰ At a time, three switches(one from each leg) conduct. Two switches of same leg are prevented from conducting. Switch pair in each leg, i.e. S1 , S4,S3 , S6 and S5 , S2. One complete cycle is divide into 6 modes.

Table for gatting scheme

S.NO INTERVAL DEVICE CONDUCTING INCOMING DEVICE OUTGOING DEVICE

1 I 5, 6, 1 1 4

2 II 6, 1, 2 2 5

3 III 1, 2, 3 3 64 IV 2, 3, 4 4 1

5 V 3, 4, 5 5 2

6 VI 4, 5, 6 6 3

Waveform of gating signals

wt

wt

wt

wt

wt

wt

0

0

0

0

0

0

g1

g2

g3

g4

g5

g6

π 2

/ 3

2 / 3

Analysis of 180 degree conduction for 3-phase inverter

The waveform of 3-phase inverter for 180 degree conduction divided into six interval of 60 degree for complete 360 degree interval.

Interval 1 Operation0

3t

1

1

1

32 223

2 323

eq

s s

eq

san cn

sbn

R RR R

V Vi

R R

Vi Rv v

Vv i R

SV

R

R

R

NC

AI 1

Interval 2 Operation 23 3

t

2

2

2

32 223

23

2 3

eq

s s

eq

san

sbn cn

R RR R

V Vi

R R

Vv i R

Vi Rv v

Interval 3 Operation 23

t

3

3

3

32 223

223

eq

s s

eq

an bn

scn

R RR R

V ViR R

iv v

Vv i R

Output phase voltage for star connected load

INTERVAL I II III IV V VI

Waveform for phase voltage

wt

wt

wt

2 3

2

3

32

0

0

0

3sv

3sv

3sv

3sv

23sv

23sv

Van

Vbn

Vcn

Fourier Series for Line-to-Line Voltages

1

5 56 6

56 6

1,3,5,...

( cos( ) sin( ))2

1 ( ) ( )

4 sin( )sin( )2 3

4sin sin ( )

3 6

oab n n

n

n s s

sn

sab

n

av a n t b n t

b V d t V d t

V n nbn

V nv n tn

1,3,5,...

1,3,5,...

4 sin sin ( )3 2

4 7sin sin ( )3 6

sbc

n

sca

n

V nv n tnV nv n tn

12 23

2

0

2 ( )2

2 0.81653

L s

L s s

V V d t

V V V

Line to line rms voltage

RMS value of the nth Component

1

4 sin32

14 sin 60 0.7797

2

sLn

sL s

V nVn

nVV V

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