Loss and Thermal Analysis Considering Stator Phase Shift Effect in Dual-Stator Spoke-Array Permanent Magnet Vernier Machines

The stator phase shift (PS) of dual-stator spoke-array permanent magnet vernier (DS-Spoke-PMV) machines contributes to the high torque density, which is promising in the tilt-rotor electric vertical take-off and landing (eVTOL) aircraft. While, systematic research on its loss influence principle is still limited. In this paper, to better illustrate the PS loss constraint principle, a single-stator equivalent (SSE) model is proposed, to effectively simplify the dual-stator permeance analysis process. With SSE model, the principle of eddy-current copper loss reduction, PM loss reduction, and iron loss increment in PS DS-Spoke-PMV machines are specifically revealed. Moreover, a comparative study on temperature rise is carried out, with and without PS design. It has been found that the steady rotor temperature rise with PS is decreased up to 21°C, contributing to the high PM demagnetization resistance capability, and leading to a 11% efficiency rise with the output power doubled.