Design Optimization of an Interior Permanent Magnet Synchronous Machine with Asymmetric and Auxiliary Slot Structure

The interior permanent magnet synchronous motor (IPMSM) is widely used for electric vehicle driving applications since it has high torque and efficiency. However, torque ripple is very high which is a main drawback of the IPMSM. Its torque ripple can be reduced by designing the auxiliary slots on the rotor and stator surfaces and designing its permanent magnet and flux barrier with an asymmetric structure. Meanwhile, the design parameters will be increased greatly if the above design methods are employed for the IPMSM, which will make the machine difficult to design and optimize. In this paper, a four-stage multi-level optimization design process (FSMLODP) is proposed to optimize IPMSM with the double-layer asymmetric and rotor auxiliary slot structure for achieving low torque ripple performance. The effectiveness of the proposed FLMLODP is verified by three different IPMSMs, it can be seen that the torque ripple of IPMSM can be reduced greatly by taking asymmetric and rotor auxiliary slot design for the IPMSM. The torque performance of optimal IPMSMs using conventional asymmetric main parameter design optimization (CAMPDO) methods and FSMLODP was compared and verified FSMLODP is effective and efficient.