Full bridge driver for multi Kw supply

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twenglish1

New member
I took a break for a while on designing my switch mode plasma cutter/welder, I have been doing a lot of reading and research on the subject and revised my design, I will be using two half bridge igbt modules configured in a full bridge setup, the modules are rated at 150 amps continuous at 1000volts, I decided to go with the EE80 cores, how much power can they handle? I have 8 pairs so paralleling them is an option, however before I get into transformer design I would like to perfect the IGBT drive circuitry and the inverter portion of the design which smps driver ic would you recommend using? The input voltage to the inverter will be about 330vdc, I have some large capacitors for the initial rectifier stage, I have 6 890uF 400 volt capacitors and 3 3300uF 400v capacitors, also have lots of spare igbt modules that I hopefully won't need. Anyway I am in need of some pointers as to where I should start in designing the full bridge driver, gate drive transformer and also I understand the dangers involved, safety pointers are always welcomed but I don't want to be told it can't be done and to not do it
 
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twenglish1

New member
Here is the schematic so far, i realize that it still needs alot of work, also i think i will be using a gate drive transformer instead of the transistor pairs, since the transistor pair method would require an isolated power supply for each switch, anybody see any other aspects that i should change?

 
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twenglish1

New member
In the schematic, what is the purpose of the circuitry between the gate drive transformer secondarys and the igbt gates? My guess is to prevent a short circuit caused by two high sides or two low sides both being activated at once?
 
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KX36

New member
I can't zoom in on the schematic from this PC, so it's a little unclear but it looks like it's a gate turn off circuit to speed up turn off. This would help to reduce the risk of shootthrough as you have speculated, but also just plain reduce switching loss. big IGBT modules have big gate capacitances which store a lot of charge. They consequently need powerful drivers to turn them off and on. There might also be a DC recovery circuit in there. I really can't tell on this PC.

The gate drive transformer's leakage inductance can give a relatively high impedance through which the gate would have to charge and discharge, so transistor drivers after the GDT are not uncommon.
 
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