What is the difference in the use of harmonics between a Chorus motor and a conventional 3-phase motor?
A – The effect of harmonics on 3-phase machines is well known. Harmonic components in the drive waveform produce rotating magnetic fields that are superimposed upon the fundamental rotating field. The fundamental rotating field essentially swamps the harmonic components, but each component has its effect on machine output. For example, any fifth harmonic component in the drive waveform will produce a rotating field with the same pole count as that of the fundamental, but rotating in the reverse direction at five times the speed of the fundamental. A slight amount of fifth harmonic content in the drive feeding a 3-phase machine will cause substantial losses, a noticeable reduction in efficiency, and an increase in machine heating. In the Chorus technology, the rotating fields produced by the harmonics of any reasonable drive waveform are similarly swamped by those of the fundamental, with the exception of intentional pole changing. These harmonics are superimposed upon the fundamental r
