Hi, I am also facing the same problem, getting voltage spikes on the dc line, my dc voltage is 65V, when switching spikes are around 130v, what might be problem?
gate voltage is 12v, high side is bootstrap, i reduced gate voltage then I can get spike reduced to 80v, but this will increase power loss, increased gate resistance to reduce spike..but I don't understand why such big spikes are coming, is it due bootstrap not discharging completely..cap is 2.2uf calculated with silabs bootstrap calculator app note. Is bootstrap really help helpful or not..what should I do..my scheme would be as AN794 app note..please help





Moderator's Note:
Please don't hijack other member's thread, now you have your own.
This thread was split from --
Three phase inverter
https://forum.allaboutcircuits.com/threads/three-phase-inverter.64418/#post-1099632

 

Hi Raj, welcome to the forums.

Which AN794 do you mean? I web searched it and came up with nothing relevant. Please provide a direct link.

 

Also post a schematic.