A question for the chaps repairing inverters.

I have a 1kVA  fivestar  UPS/inverter with shorted H bridge IGBT transistors after customer tried to power an undersink water heater and kettle at the same time.

I would like to test the drivers before replacing the IGBT's.

What is the best way to do this ?

Can I scope the gate drive waveform with the IGBT transistors out or is there a better way to test them ?

Thanks

20 hours ago, DaveS said:

Can I scope the gate drive waveform with the IGBT transistors out or is there a better way to test them ?

I don't know about better, but the way I do it is with a dual power supply (maybe I needed three, I can't recall exactly now). One on +12V, the other on the isolating driver chip (ACPL-T350). (Maybe I put the third one on -12 V, but I can't see how that would be necessary now.) If it's Axpert compatible, there will be a diode (e.g. D11 for QA1 on my schematic) that I can short with tweezers and watch the gate drive go from about -5V to about +13 V. It's painful with all the connections you need at once, but it gives great peace of mind that the IGBT gate drivers are working end to end.

Edit: in off-grid Axperts, the processor drive is open collector, so it's safe to short the output to ground. That may not be the case for all variants.

Edited August 25, 20224 yr by Coulomb

Thank you @Coulomb

Will try your tried and tested method .