An Egg-shaped Diagram and its Discrepancies in Switched Reluctance Machines.

Abstract

Recently, switched reluctance motors have attracted attentions from industries. It is a common practice to develop several test machines for performance evaluation. One way to make a comparison among several test machines is to draw an efficiency map in a speed and torque plane, however, it is rather complicated. For an easy comparison, a machine parameter measurement with an egg-shaped diagram has been proposed by the authors. In this method, it is possible to measure a inductance ratio, which indicates the saliency of switched reluctance machines. In this paper, a calculation of tolerance between theoretical egg-shaped curves and measured powers is proposed. It is found that the tolerances are within 4% as a result of several test machines. Although discrepancies in instantaneous current waveforms and voltage phase angles are seen, the obtained machine parameters indicate an exact relation between input power and required apparent power.