Shape Design Optimization and Comparative Analysis of a Novel Synchronous Reluctance Machine With Grain-Oriented Silicon Steel

Synchronous reluctance machines (SynRMs) have received much research attention due to their simple structure, wide speed regulation ability, and no need for permanent magnet excitation. However, the SynRM still has the disadvantages of lower output torque, lower power factor, and lower efficiency compared to permanent magnet synchronous machines (PMSMs). In this article, a novel SynRM with a rotor core made of grain-oriented (GO) silicon sheets (GO-SynRM) is proposed. By taking the merits of the high permeability in the rolling direction (RD) of GO silicon sheets, the d-axis magnetization characteristic of the SynRM has been improved. By taking the new rotor topology, the torque ability and power factor of the GO-SynRM can be improved compared to SynRM with a non-GO (NGO) silicon steel rotor core (NGO-SynRM). Moreover, the shape of the rotor flux barrier of SynRM has a significant impact on the performance of the machine since it determines the flux distribution. Therefore, the segmented linear interpolation method is proposed to determine the boundary of the rotor flux barrier and an arbitrary shape of the flux barrier can be obtained to improve the machine performance furthermore. Meanwhile, the multilevel optimization (MLO) method is employed to optimize the flux barrier shape of NGO-SynRM and GO-SynRM to reduce the optimization time as there are too many design parameters. Finally, the performances of the above machines are comparative analyzed and discussed.