Magnetic loss in AC motors in transportation

Abstract

This paper describes a very practical model that can be used to determine the magnetic loss in motor driven by a nonsinusoidal waveform such an inverter waveform (e.g. PWM, six-step). We have shown that if either the classical eddy current losses or excess eddy current loss is the dominant loss mechanism, the loss due to nonsinusoidal waveform can far exceed die loss for the corresponding sinusoidal wave-from even when the frequency and the peak flux density are the same for the two types of waveforms. We pointed out that in such cases it is not appropriate to use the manufacturer supplied data for the sinusoidal waveform to describe the loss for nonsinusoidal waveforms. However, we have provided some simple formulas in this paper which can be used to calculate loss for nonsinusoidal waveform using the manufacturer supplied data.