Slotless Disk Type Resolver: A Solution to Improve the Accuracy of Multi-Speed Wound Rotor Resolvers

A common solution for increasing the accuracy of wound-rotor (WR) resolvers is to increase the number of poles. To achieve a compact design, fractional slot concentrated winding (FSCW) is used for multi-pole WR resolvers. However, employing such windings leads to rich sub-harmonics in the induced voltages. To suppress these undesirable sub-harmonics, multi-layer windings with an appropriate shifting angle between the layers are suggested. However, the said shifting angle is limited by the slot pitch so that the capability of the multi-layer winding is not utilized fully. To overcome the mentioned deficiency, a slotless disk type configuration is proposed in this article. Then, an optimization based on the winding function (WF) model of the sensor is carried out to achieve an optimal winding configuration. 3-D time-stepping finite element method (FEM) is used to verify the success of the proposed analytical model and the performed optimization. Finally, a prototype of the optimal configuration is built for experimental measurements.