also - most of those " spikes " are common mode " CM " pickup due to poor probing techniques
try shorting the probes on the pos rail and then the neg rail and see if the same " spikes " are there - if they are
think about your probing.
--- Updated ---
Is there a diode in your high side power feed ?
the complete and LEGIBLE schematic would be helpful
Attached the power supply and gate schematic.also - most of those " spikes " are common mode " CM " pickup due to poor probing techniques
try shorting the probes on the pos rail and then the neg rail and see if the same " spikes " are there - if they are
think about your probing.
--- Updated ---
Is there a diode in your high side power feed ?
the complete and LEGIBLE schematic would be helpful
Its a custom power supply. Im not observing the spikes on the 5v input of the gate driver. Only the 15v side is affectedSo you're observing these spikes on the input side of the isolated drivers? Could be parasitic capacitance in the isolation transformers. Are they off-the-shelf power supplies, or custom?
The schematic you attached isn't legible...
i shorted the probe at the 15v rail and im observing the 40khz spikeyes, yes, SHORT the scope probe on the +ve 15V rail, i.e. probe tip and gnd on this point
do the same on the 0v of the 15V supply
if you still see the spikes ( you should see zero - as the probe is shorted ) then the problem is in common mode noise - and the spikes are artifact only.
Attached the power supply and gate schematic.
Pos and neg rail meaning should i probe the power supply to the isolation transformer?
Thanks for the reply
Ok now we get some more details.Its a custom power supply. Im not observing the spikes on the 5v input of the gate driver. Only the 15v side is affected
Thanks for the reply
Observing this in both high and low side driver.Ok now we get some more details.
Are you observing this on the supply for the high side driver, or the low side driver, or both?
What sort of probe(s) are you using to make these measurements?
when i increase the dc voltage for the inverter , the amplitude of the spike goes up as well, is there a way i can eliminate common mode noise with any CM chokes or is board redesign required?Do you know about CM ( common mode ) noise and how it increases as your voltage rail goes up ?
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