The figure on the left illustrates a general circuit

topology of an inverter welding power source. This

circuit topology is composed of four stages: A) Rectifier

stage, B) PFC & Boost stage, C) Power stage, and D)

Output stage. Input power from a power grid enters

the rectification stage to be rectified to a DC value

and is processed via a power factor correction boost

converter. From there it enters the power stage which

employs a full bridge inverter to convert the voltage

back to AC at high frequencies typically from 50Khz

to 100Khz. The AC signal is then stepped down via T1

transformer which then gets rectified and smoothed

out at the output stage.

The figure on the right illustrates an AC motor

drive that utilizes a resonant DC link inverter. A

resonant link (L1, C2) is affixed to the DC bus line

of a pulse width modulation inverter. The resonant

link is then ‘excited’ and maintains resonance

through the control of the IGBTs in a way that

the resonating dc voltage bus frequently reaches

zero volts. The IGBTs are turned on and off at

zero voltage and are synchronized to match the

zero voltage crossings to achieve the desired low

switching loss. An active clamp circuit (Q7, C1) is

added to clamp down unwanted overshoot when

the DC inverter current decreases abruptly caused

by the switching behavior of the IGBTs.

C2

Motor

Q1

Q2

Q3

Q4

Q5

Q6

Q7

C1

3-Phase AC

Gate Drive Controller

Vs

L1

C1

Q2

Q3

Q4

Q5

D1

D3

D2

D4

Q1

D5

D6

D7

R1

C2

C3

R2

C4

C5

230VAC

Rectifier

Power

Factor

Correction

Boost

Converter

Power Stage

Full Bridge Inverter

Step Down

Transformer

Output Stage

Vout+

Work Clamp

PFC

Controller

Gate Drive

Controller

L1

L2

www.ixys.com

PB60IGBTA3B3C3 1.4

January 2009

Multi-Process High Frequency Inverter Welder

AC Motor Drive (Resonant DC Link Inverter)

applIcaTIons

Power inverters

ƒ

Uninterruptible power supplies

ƒ

Motor drives

ƒ

Switch mode power supplies

ƒ

Power factor correction circuits

ƒ

Welding machines

ƒ

Lamp ballasts

ƒ

feaTures

Optimized for low switching &

ƒ

conduction losses

Square RBSOA

ƒ

High current handling capability

ƒ

International standard packages

ƒ

BenefITs

High power density

ƒ

Low gate drive requirement

ƒ