Effect of Stray Magnetic Field on Position Sensor Used in Permanent Magnet Synchronous Machine (PMSM) Drive for Propulsion System

Permanent magnet synchronous machines (PMSMs) are a widely used traction motor topology because of their high torque and power density which results in a compact mechanical envelop. External electronics control these brushless permanent magnet machines and a position sensor such as a resolver is required to determine the position of the rotor. The position sensor can be located in close proximity to the stator winding in order to reduce the overall package size of the system. However, the performance of the position sensor is impacted by the high electromagnetic field (stray field) that is generated by the current through the end winding of the machine. This research proposes a Finite Element (FE) based modeling technique to analyze the stray field impact on the position sensor performance and the mitigation technique by utilizing electromagnetic shielding. Effects of the stray field on the resolver signals are first discussed. Then, a reduced-order FE technique is proposed for modeling the interference and an electromagnetic shield is designed using this technique.