Analysis on the Charateristics of Variable Reluctance Resolver Considering Uneven Magnetic Fields

Variable reluctance (VR) resolver is widely used in traction motor for battery-powered electric vehicles (EVs), as well as for hybrid EVs as rotor position sensor. VR resolver generates absolute position signal using resolver-to-digital converter (RDC) to deliver the exact position of permanent magnets in the rotor of a traction motor to the motor controller. This paper deals with analysis methodology on a VR resolver using cosimulation analysis with RDC tracking algorithm for position-angle detection considering uneven magnetic fields. The eccentricity of the VR resolver, short-circuit conditions of the excitation and output-signal coils, and shape of rotor saliency are considered as sources of uneven magnetic fields in the VR resolver. Two-dimensional FEM is used for the SIN and COS output-signal waveforms, and these waveforms are converted into absolute position angle using RDC algorithm. To verify the analysis results of the proposed resolver, experiments on different uneven magnetic field conditions were conducted and compared with the simulation results.