Huge spikes at output voltage

Thread Starter

Tahsina Hossain

Joined Jan 16, 2015
Hi there everyone,

I have developed a single phase full bridge inverter but at the output I am observing huge spikes, what confuses me most is that: I have spike across one node to ground but not on the other.

I have always got constructive and useful feedback from this forum, please help me this time as well.

I am using bipolar spwm from msp430 to generate the control pulses.20150303_145834.jpg


Joined Nov 30, 2010
It looks like 4 gate drivers running 4 IGBTs but the gates are drawn differently. Does that mean this is not a matched set of 4?


Joined Mar 16, 2015
Looks very much like classic overvoltage spikes due to parasitic stray inductances in the commutation path.
You can reduce switching speed (defined by gate-resistance) which might unfortunately increase switching losses. And you should take care about a low-inductive circuit design on your PCB.

Here is a nice animation (Java-applet) which shows what might be going on:
(works only if Java-applets are allowed by the browser)