Investigation and Comparison of Different Rotor Profiles for Variable Reluctance Resolvers

A resolver is an electromagnetic transducer sensor that has been used in the control of electric motors for many years. They allow to read speed and position through the analog signal. Since they provide analog output, they are more reliable than other feedback devices with digital outputs in determining position and speed, especially in harsh environments. Therefore, they are frequently used in many areas in industry. In this paper, a study of a 3-pole variable reluctance resolver with different rotor profiles is presented. The influence of the various rotor profiles with low and high saliencies on the performance of a resolver has been investigated in the paper. Hybrid 2D finite element analysis (FEA), including both static and transient simulations, is used to evaluate electromagnetic behavior. Based on the FEA results, a prototype is built and experimentally validated through both static and dynamic tests using a special resolver test bench. Test results show that the resolver operates with low total harmonic distortion (THD) below 2% and provide high position accuracy, with an average absolute position error (AAPE) of 0.089° and a maximum position error (MPE) of 0.206° under dynamic conditions. Consequently, the proposed rotor geometry provides improved signal strength and accurate position estimation, demonstrating a cost-effective and high-performance solution for industrial applications.