Have you had a chance yet to scope the wave-form of the drive power? I have been trying to do so with commercial VFDs and a commercial (induction) motor to start getting some understanding of what is going on. There are many images on the 'net of these wave-forms, pretty easy to understand and look like what I would expect in theory. However, on my scope I see mostly garbage. It is very difficult to even identify where the PWM of the carrier is changing to create the "sine". My scope is good, but I may not know how to use the more fancy triggering schemes; that I admit. The induction motor (any motor, probably) must create a lot of noise spikes, so I tried connecting the VFD to pure resistive loads, but really no better. It seems that the switching of the IGBTs is intrinsically creating the noise.