Research of Asymmetric Rotor Structure in Magnetic-Field-Shifting and Flux-Intensifying IPMSM

In order to meet the increasing torque and speed requirements of various applications, the widely used interior permanent magnet synchronous machine (IPMSM) requires new design and analysis methods that can further improve performance. The electromechanical energy conversion of IPMSM relies on the interaction of various magnetic fields. So, studying the characteristics of “excitation-magnetic permeability-magnetic field” is effective in improving performance. This article proposes an analysis method for these characteristics and a design method based on asymmetric structures and summarizes how each characteristic affects performance and the effects of changing the above. Taking conventional IPMSM, magnetic-field-shifting (MFS) IPMSM, and flux-intensifying (FI) IPMSM as examples, the relationship between the above characteristics and performance with different phases is theoretically analyzed. The method of changing the phase and other characteristics of the magnetic fields to increase torque and speed during normal and flux-weakening (FW) operation has been researched. Based on the above, the design method using asymmetric structures to optimize characteristics and improve performance has been verified by finite element analysis (FEA).