Analytical Model for IPMSMs With Mixed Eccentricity Considering the Effect of Eccentricity on Core Saturation

Abstract

Analytical model (AM) is a time-saving and low-cost way to predict the open-circuit magnetic field of interior permanent magnet synchronous motor (IPMSM) with mixed eccentricity (ME), compared to experimental or numerical methods. However, the effect of ME together with rotor rotation on saturation is difficult to be considered in AM. This article proposes a new iterative approach with two loops that can accurately obtain the time-varying nonuniform saturation of inner and outer magnetic bridges (MBs) and develops a simple and effective AM for IPMSM with eccentricity. The motor is divided into several sections along circumference. The magnetic equivalent circuit (MEC) model is improved by introducing the equivalent airgap reluctance after eccentricity into it to iterate to get the magnetic flux density of IPMSM with ME. Then, the magnetic flux density obtained from the improved MEC model is modified, according to the actual airgap length distribution in this section. The improved MEC model combined with the proposed iterative approach can consider the effect of eccentricity, slotting, and rotor rotation on saturation. It can effectively capture the open-circuit magnetic field distribution of IPMSM with ME, even under large eccentricity ratio. Finally, the accuracy of the proposed model is verified by finite element method (FEM) and experiments.