Paralleling IGBT bricks for H-bridge

[Patrik]

Hi!
I am new here and I want to ask about paralleling IGBT bricks to create an H-bridge for my SSTC.
I have two 6MBI75UC-120-52 IGBT bricks each consisting of three half bridges for 3 phase inverter.
Here is the datasheet, if you want to check it out: http://www.bjrtd.com/pdf/6MBI75UC-120.pdf

Now, I want to put all of the half brigdes inside the brick in parallel, creating one big halfbridge, so that I can run about 100A through the primary coil
and out of those two paralleled modules create a full bridge to drive the primary.
I have done some research before and I know, I should use separate matched gate resistors and drive them from single GDT.
I will be placing a antiparallel doide to the resistor to speed up the discharging of the gate.

As a driver I will be using a Steve Wards universal driver 1.3.

Do you think, that this settup will be powerful enough to drive the IGBT transistors? And should I replace the 7824 regulator with a separate power supply or it is fine to keep it in the circuit?

Thank you wery much!

[davekni]

Are you building a DRSSTC (Dual Resonant SSTC where the primary coil and capacitor are tuned to match or slightly below secondary frequency)?  Or is this a normal SSTC with non-resonant primary coil?  For normal SSTCs, most designs use FETs rather than IGBTs.  For the short bursts of a DRSSTC, that IGBT brick could likely handle a peak of 300A per half-bridge, or 900A for all three in parallel.  Certainly at least 200A per half-bridge as is listed as the 1ms maximum in the specification.

Other details about your coil would help too - frequency in particular.  A dump from JavaTC would be even better.

[Patrik]

Hi!
I am building a regular SSTC, without the primary resonance capacitor. I know, that most people use mosfet transistors, but I have these at home, and want to try them in this circuit.

The primary has an inductance of about 12uH.
The javaTC output:

[davekni]

Switching energy loss will dominate when using IGBTs for a SSTC (be much higher than conduction losses).  For 10-20% duty cycle on your 73kHz coil, you probably could run the three paralleled half-bridges at 100A.  Perhaps higher - depends largely on the current at switching times.  With your high-Q secondary, before long arcs form, current may drop fairly low before switching.  Scope at low duty cycle (and measure IGBT temperature) before increasing duty cycle.

[Mads Barnkob]

You are mixing some things together here, as Dave points out there is a problem with switching losses by using IGBTs in a SSTC.

You also mention that you will use the Steve Ward Universal Driver 1.3b , but that is a DRSSTC driver that needs a powerful primary cirucit feedback, which you can not get from a SSTC as its primary circuit is not resonant.

You need to make choice about building either a SSTC or DRSSTC and then use the right parts and drivers for each kind.