As an aspiring1 musician, I sometimes add a little distortion to my guitar amp to make the sound more interesting or to cover up my mistakes. However, when dealing with a drive connected to a motor, the best distortion is no distortion. As Dr. Ned Mohan put it, the goal is harmony, not harmonics! In the case of AC (alternating current) induction motors, the desire is to achieve the cleanest sine waves possible coming out of the drive.