Winding Function Model for Predicting Performance of 2-DOF Wound Rotor Resolver

Two-degree-of-freedom (2-DOF) electrical machines require position sensors for their motion control. In comparison with using two independent sensors, using a 2-DOF sensor enhances the closed-loop control system’s performance. However, due to the 3-D structure of the 2-DOF sensor, its performance evaluation needs 3-D analysis. Also, due to helical motion the accuracy deterioration of the sensor, under mechanical faults needs more attention. Although the finite element method (FEM) is the best way to simulate such sensors, most of the commercial packages for transient finite element simulations are not able to consider two separate motions simultaneously. Furthermore, FEM has a high computational burden that limits its usage in iterative design and optimization process or under mechanical faults. Therefore, developing a fast, and comprehensive analytical model to be used for performance evaluation of helical motion resolvers under mechanical faults is appreciate. Consequently, in this article, an analytical model based on the winding function method (WFM) is developed for a helical motion resolver. The model can predict the performance of the sensor in a healthy condition, as well as that under eccentricity fault. The success of the model is verified using 3-D FEM and the experimental measurements on the prototype sensor.