Spikes cause IGBT gate driver to modify wave shape -help

[moshik3]

Hi,

I am using a PIC (18F14K22@16MhzX4) to send a pulse of about 100uSec to a gate driver (FAN3214).
PIC has 0.1uF and 100uF bypass both ceramic SMD.
the gate driver is powered by 18-19v, also has 0.1uF and 100uF bypass both ceramic SMD.

The gate driver is powering an array of 10 IGBTs (through 20-Ohm gate resistor each)
The IGBTs are controlling a xenon flash lamp.

Everything works nicely, except one thing:
I set the unit to produce that 100uS pulse, at 10Hz (10 times per second),
I randomly get "brighter" flashes, which correspond to some noise in the gate driver output to the IGBT,
and also on the gate driver input from the PIC.

in the video below i recorded the wave form of the 18v supply to the gate driver (blue)
and the output of the gate driver to the IGBTs (yellow).

near the end of the video (at 0:22) you can see some additional noise\spikes in the middle of the wave form,
the brighter flashes appear just when these noise appear in the scope.
it can function very well and consistently for a few seconds, until that happens.
:arrow:https://videobam.com/RGPCe (cick the "close to play" button)

I have bypass capacitors everywhere,
I even added a 1nF capacitor on the gate driver input side.
Tried both powering from mains adapter and isolated batteries.
Tried different batteries - one for the 5v PIC and one for the 18v IGBT.

Thanks for helping out

 

[FvM]

You are on this board since some time. Why are you still cross-posting?

P.S.: You better answer here: https://www.edaboard.com/threads/299893/

 

[kripacharya]

Why does your 18v supply (blue trace) have almost the same shape as your gate drive (yellow) ? Shouldn't that be a steady 18v ? What am i missing...