Split Ratio Optimization Analysis for Inner Boost Permanent Magnet Motor Considering Maximum Overload Capacity

Abstract Inner boost permanent magnet motor (IBPMM) can make full use of the internal space of the motor rotor, and the inner stator only runs when overloaded, so it has a high short‐term overload capacity. The split ratio of IBPMM affects the electromagnetic performances of the inner and outer stators simultaneously, so the rated efficiency, maximum overload capacity and electromagnetic load of the IBPMM are all dependent on the split ratio. In this paper, the structure and operation principle of IBPMM are explained first. Then, aiming at the problem of large error of traditional analytical method, an equivalent magnetic network (EMN) model with sliding mesh is established to consider the saturation effect, flux leakage and improve the calculation accuracy of electromagnetic performances of the IBPMM. This model is used to optimize the split ratio of IBPMM with limited copper loss and fixed permanent magnet spacing. The influences of the split ratio on rated efficiency, maximum overload capacity, electromagnetic load and input current of IBPMM under the voltage limit are analyzed. The temperature distribution of IBPMM with different split ratios are compared by transient finite element method (FEM). Finally, the accuracy of the analysis is verified by FEM and prototype experiments. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.