180 & 120 degree conduction mode inverter

8/10/2019 180 & 120 Degree Conduction Mode Inverter

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Three-Phase Inverters

Consider three single-phase inverters inparallel, driven 120apart.


2/27

Three-Phase Inverter (continued)

Three single-phase full bridge inverters

12 transistors, 12 diodes, 3 transformers

Could it be simpler?


3/27

Alternative (Preferred) Configuration

6 transistors, 6 diodesconduction for 120or 180


4/27

180Conduction

Three transistors ON at a time


5/27

Summary Table


6/27

Waveforms for 180Conduction


7/27

Phase Voltages for 180Conduction


8/27

Waveforms for 180Conduction


9/27

Summary Table


10/27

Mode 1 Operation


11/27

Mode 1 Operation

1

1

1

3

2 2

2

3

2 3

2

3

eq

s s

eq

san cn

sbn

R R

R R

V Vi

R R

Vi Rv v

Vv i R

03

t

Q1, Q5, Q6conduct


12/27

Summary Table


13/27

Mode 2 Operation


14/27

Mode 2 Operation

2

2

2

3

2 2

2

3

2

3

2 3

eq

s s

eq

san

sbn cn

R R

R R

V Vi

R R

Vv i R

Vi Rv v

2

3 3t

Q1, Q2, Q6conduct


15/27

Summary Table


16/27

Mode 3 Operation


17/27

Mode 3 Operation

2

3t

3

3

3

3

2 22

3

2

2

3

eq

s s

eq

an bn

scn

R RR R

V Vi

R R

i

v v

Vv i R

Q1, Q2, Q3conduct


18/27

Phase Voltages for 180Conduction


19/27

Fourier Series for Line-to-Line Voltages

1

5 5

6 6

5

6 6

1,3,5,...

( cos( ) sin( ))2

1 ( ) ( )

4

sin( ) sin( )2 3

4sin sin ( )

3 6

oab n n

n

n s s

s

n

sab

n

av a n t b n t

b V d t V d t

V n n

b n

V nv n t

n


20/27

For the other Line-to-Line Voltages

1,3,5,...

1,3,5,...

4

sin sin ( )3 2

4 7sin sin ( )

3 6

s

bcn

sca

n

V n

v n tn

V nv n t

n


21/27

Line-to-Line rms Voltage

12 23

2

0

2( )

2

20.8165

3

L s

L s s

V V d t

V V V


22/27

rms value of the nth Component

1

4sin

32

1

4 sin 600.7797

2

sLn

sL s

V nV

n

n

VV V

Fundamental Component


23/27

Line-to-Neutral Voltages

2

0.471433

sL

p s

VV

V V


24/27

Phase Voltages (Y-connected load)

1,3,5,..

1,3,5,..

1,3,5,..

4sin( ) sin( )

33

4 2sin( ) sin ( )

3 33

4 4sin( ) sin ( )3 33

saN

n

sbN

n

scN

n

V nv n t

n

V nv n t

n

V nv n tn


25/27

Line Current for an RL load

2 21,3,5,...

1

4sin sin( )

33 ( )

tan

sa n

n

n

V ni n t

n R n L

n L

R


26/27

DC Supply Current

IL=3Iois the rms load line current

Vo1= fundamental rms output line voltage

Iois the rms load phase current

1= the load impedance angle at the fundamental

frequency

11

11

( ) ( ) ( ) ( ) ( ) ( )

....

3 cos( )

3 cos( )

s s ab a bc b ca c

os o

s

os L

s

v i v t i t v t i t v t i t

VI I

V

VI I

V


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Three-Phase Inverter with RL Load

180 & 120 degree conduction mode inverter

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