Optimal Slot Design of IPMSM in Railway With Independently Rotating Wheelsets

This paper proposes a quasi-semi-closed (QSC) slot design method for an open-slot-type interior permanent magnet synchronous motor (IPMSM) for independently rotating wheelsets necessary to reduce the total harmonic distortion of no-load back-electromotive force and the torque ripple in the IPMSM. Four different slot-opening models were selected-the basic model, hairpin coil model, magnetic-wedge model, and QSC-slot model-and 2-D finite-element analysis was performed under open-circuit and load operations for each of the four models. Next, the relationships among the cogging torque, the torque ripple, and the saturation phenomenon in the core were analyzed. In addition, the manufacturing process, manufacturing cost, fill factor, end-winding resistance, copper loss, and efficiency were investigated. The experimental results verify the accuracy of the proposed method.