ECE 442 Power Electronics 1

Series Resonant Inverter with Bidirectional Switch

ECE 442 Power Electronics 2

Turn Q1 ON at t = 0

A “resonant” pulse of current flows, charging C to VC1, Q1 turns OFF

ECE 442 Power Electronics 3

C charges to VC1, Q1 turns OFF

ECE 442 Power Electronics 4

C discharges via D1 and Vs

• For t > t1

– The capacitor acts as a voltage source

– Current io reverses, and flows via D1 to VS

ECE 442 Power Electronics 5

V1220 V

D2DIODE_VIRTUAL

L120uH

C12uF

3

0

D1DIODE_VIRTUAL

1

2

“Idealized Version”

ECE 442 Power Electronics 6

ECE 442 Power Electronics 7

Half-Bridge Series Resonant Inverter

ECE 442 Power Electronics 8

Turn Q1 ON, Resonant Pulse of current appears.

ECE 442 Power Electronics 9

Turn Q2 ON, Resonant Pulse of current appears in the opposite direction, and goes to zero.

ECE 442 Power Electronics 10

Waveform Summary

ECE 442 Power Electronics 11

Overlapping and Non-Overlapping modes

• Non-Overlapping Mode– Firing of the switching device is delayed until the last

current oscillation through the diode is completed

ECE 442 Power Electronics 12

Overlapping and Non-Overlapping modes

• Overlapping Mode– Firing of the switching device occurs before the last

current oscillation through the diode is completed.– This increases the output frequency and the output

power

ECE 442 Power Electronics 13

MultiSim Simulation

D2DIODE_VIRTUAL

L

20uH

C

2uF

D1DIODE_VIRTUAL

V1110 V

V2110 V

J11 V 0mV

J21 V 0mV

XFG1

D3

DIODE_VIRTUAL

D4

DIODE_VIRTUAL

Rsample

1 Ohm

XSC1

A B

G

T

ECE 442 Power Electronics 14

Non-Overlapping Mode

ECE 442 Power Electronics 15

Overlapping Mode

ECE 442 Power Electronics 16

Full-Bridge Series Resonant Inverter

ECE 442 Power Electronics 17

Frequency Response of

Series-Resonant Inverters

ECE 442 Power Electronics 18

Series-Loaded Inverter

• Load Resistor in series with L and C

ECE 442 Power Electronics 19

0

0

0

( )( )

1( )

1( )

11

1

1( )

1

o

i

o

s

ss

V j RG j

V j R j Lj C

G jL

j jR RC

LCL

QR

G jQj jQ

ECE 442 Power Electronics 20

0

0

0

0

0

2 2

1( )

1

1( )

1

1( )

11 ( )

1( )

11 ( )

ss

s

s

s

G jQj jQ

G j

jQ

u

G jjQ u

u

G j

Q uu

ECE 442 Power Electronics 21

Frequency Response

ECE 442 Power Electronics 22

Parallel-Loaded Case

ECE 442 Power Electronics 23

2

0

0

2

20 0

1

1( )

( )( ) 1

1

1( )

1

1

1

1( )

1

o

s

s

Rj C

RV j j C

G jV j

Rj C

j LR

j C

G jL

LC jR

LCR

QQ L

G jQ

j

ECE 442 Power Electronics 24

2

20 0

2

0 0

0

2

2

2 2

1( )

1

1( )

1

1( )

1

1( )

(1 )

G jQ

j

G j

jQ

u

G ju

u jQ

G ju

uQ

ECE 442 Power Electronics 25

Frequency Response

ECE 442 Power Electronics 26

Series-Parallel Loaded Case

ECE 442 Power Electronics 27

Frequency Response