Novel Wedge-Less Stator to Reduce Shaft Voltage in IPMSM for EV Propulsion Considering Manufacturability

This study proposes a novel wedge-less stator (WLS) geometry to reduce the winding-to-rotor capacitance C_wr for mitigating shaft voltage (SV) in electric vehicle (EV) propulsion motors, with consideration for manufacturability. The WLS geometry features a unique structure termed a winding holder (WH), positioned beneath the winding, which not only blocks the electric field between the winding and rotor but also secures the winding without the wedge. Initially, the working principle of the proposed geometry is investigated in terms of electric fields. Subsequently, a comparative study of a wedged stator model (WSM) and the WLS model (WLSM), including a base model, is conducted to evaluate the C_wr mitigation effect according to the stator geometry. Finally, the WSM and WLSM are optimized to enhance torque and electrostatic performances. Finally, prototypes of optimized models are fabricated and tested to validate the improved performance and manufacturability of the proposed concept.