Considerations on Spatial Harmonics Due to the Winding Factor in a Multi-Speed Resolver

Abstract

A multi-speed resolver is one of the most accurate angle sensors, which are transformers having primary rotatable windings with respect to their secondary (pick-up) windings. Multiple speeds are possible because each winding consists of a two-pole winding and a multi-pole winding. We propose a new multi-pole pick-up winding method, in which the angle accuracy is governed by the multi-pole winding, which is a sinusoidally distributed winding on a fractional slot structure (fractional winding). Through comparison of the new structure with conventional structures, the following conclusions were obtained: (1) the suggested fractional windings lead to suppression of maximum spatial harmonics; (2) surviving spatial harmonics on the winding factor involve the number of slots in the repeatable group (S_g); (3) the accuracy of the practical test results indicates that the fractional winding is superior to the conventional winding.