A Reverse-Salient Permanent Magnet Synchronous Motor for Electric Vehicles Considering Operating Conditions

Permanent magnet synchronous motors (PMSMs) provide many attractive electromagnetic performances such as high torque density, high efficiency and simple structure, which make them more competitive in electric vehicles (EVs). However, designing a PMSM with a wide constant-power speed range and high power factor at high speeds is still full of challenges and requires further effort. In this paper, the performance of vehicle motors considering their operating conditions is analyzed. The design rules of the reverse-salient permanent magnet synchronous motor (RSPMSM) are summarized, and an RSPMSM is proposed. The principle of the RSPMSM with high torque especially in the flux-weakening states is studied by analyzing the variable flux leakage and variable saliency ratio in detail. The electromagnetic performance of the proposed RSPMSM is investigated using the finite element method (FEM), and its prototype is manufactured and tested. The experimental results show that the constant-power speed range is 5.5:1, and the power factor is close to 1 at high speed. Thus, the RSPMSM proposed in this paper is a favorable candidate for EVs.