A Reverse-Salient Permanent Magnet Synchronous Motor and Its dq-Axis Current Distribution Laws

The reverse-salient permanent magnet synchronous motors (RSPMSMs) have attracted considerable attention in electric vehicles due to their wide constant-power speed range. However, the
dq
-axis current distribution laws of the RSPMSM are absent, and the relationships between motor parameters and the constant-power speed range are still unclear. First, the flux-intensifying effects and
dq
-axis current distribution laws of the RSPMSM are investigated. Second, the relationships between motor parameters and the constant-power speed range are summarized. Then, an RSPMSM with a wide constant-power speed range is proposed. The electromagnetic performance of the proposed RSPMSM is investigated by finite element method simulations and is compared with a conventional interior permanent magnet synchronous motor. Finally, an RSPMSM prototype is manufactured and tested. The results show that the RSPMSM exhibits favorable characteristics such as a wide constant-power speed range, weak flux-weakening current, high permanent magnet operating point, strong short-circuit current suppression capability, and high efficiency at a high speed. The constant-power speed range tested by the experiment reaches 5.5:1. Thus, the
dq
-axis current distribution laws, the relationships between motor parameters and the constant-power speed range are of great significance to the design of the RSPMSM.