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.

 

A circuit would help us further...

 

Useful information from us requires useful information from you.
Please post a circuit diagram.

 

Is there an inductor in the output circuit somewhere?

 

Hi there,

Yes, I should have posted the circuit earlier, was so caught up in the spike thing, I dont have any sort of inductor in the output circuit.

 

The schematic is unreadable, unless I want to spend hours unraveling spaghetti.
Take the time to re-draw this in a more orderly fashion, it will help you to communicate with others, and to clarify your own design ideas.

http://opencircuitdesign.com/xcircuit/goodschem/goodschem.html

 

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?

 

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: http://www.ipes.ethz.ch/ipes/switching/e_niederind.html
(works only if Java-applets are allowed by the browser)