I'm trying to create a single phase 120VAC VFD to run an AC motor at variable speeds.

I plan to use 4 individual IGBT's, logic level gated, to run this motor.

My question about IGBTs is (can't find an answer anywhere) - will they operate normally even when the emitter is not connected to ground?

Obviously two out of the 4 IGBTs will have their emitters connected to the AC Motor, and the other 2 IGBTs will have their emitters connected to ground.

Any input is appreciated, thanks.

 

I think they will work since you will have their emitters still connected to a driver ic of some kind. I believe you drive them like high-side MOSFETs meaning you need a boot strapped driver to raise their gates above their floating emitters.

See this app note:
http://www.ixys.com/Documents/AppNotes/IXAN0010.pdf

 

I will be using an Arduino Microcontroller to drive the IGBTs

 

If you are using IGBTs I assume you are talking higher power. Without knowing details of the parts you want to use the Arduino probably does not put out enough current to turn the IGBTs on and off fast enough.