We've got a thread going on the overall controller on DIYcar, but this is specific to the VLA driver board from this thread so I thought this would be a more appropriate place to ask.
We're getting a strange output from the VLA500 board.
At first we thought it was the IGBT, but it is not. (we have other problems with the IGBT: gate resistors etc to sort through).
The output from the P&S controller board shows a clean 8khz signal. The output from the VLA board has unstable transitions between the 8khz main pulses. They SEEM to be more prevalent when the duty cycle is ramping up and go away when it is stable.
Here are a couple of screenshots of the gate-emitter trace with the unwanted pulses. The controller board signal has clean pulses every 6.25 divisions (125 u-sec).
My son made some mods to disable the desat detection (shown) and pull the gate resistor off of the driver board.
Can you see any obvious places to start to look for the cause?
Thanks