Wye vs. Delta

[BrianG]

I still don't think the feedback pulses are perfect sine waves. You are applying a high current square wave signal to a coil. When the field collapses, it will generate a back-EMF spike. However, since this is happening kinda fast, the spikes aren't as bad as they normally would be. It probably looks more like a semi-sinusoidal pulse with a little decay before the next pulse from the ESC comes in.

Now, if we were talking about variable frequency sine-wave drives, then yes, the feedback would be a perfect sine wave. Man, I wish I still had access to a o-scope to check this!