Open-End Winding Permanent Magnet Synchronous Machine With Winding Connection Change Method for High Efficiency EV Traction

This paper proposes a winding connection (WC) change method with open-end windings (OEW) for permanent magnet synchronous machines (PMSMs). Through the proposed method, the electromagnetic performance such as torque density and efficiency of PMSMs can be improved than the conventional three-phase PMSMs. The proposed method enables to drive the PMSMs with two operating modes, which are series and parallel mode with OEW. As the series turns per phase varies with each mode, the motor parameters such as resistance,
$d, q$
-axis inductances, and flux-linkage are dependent on which mode is selected. In addition, it is possible to enhance the electromagnetic performance of PMSMs because of the improved flux-weakening characteristics due to the increased modulation index by OEW. In order to verify the results, the conventional PMSMs and OEW-PMSMs with proposed method are compared through simulations.