Prediction of Magnetic Field for PM Machines With Irregular Rotor Cores Based on an Enhanced Conformal Mapping Model Considering Magnetic-Saturation Effect

In this article, permanent magnet (PM) machines with irregular rotor cores, mainly including surface-mounted PM (SMPM) machines and surface-inset PM (SIPM) machines, are analyzed by an enhanced conformal mapping (CM) model. The three special issues have been addressed. The irregular boundary in the rotor core is divided into several segments, and the enhanced CM model can be used to deal with PM machines with irregular rotor cores conveniently. Then, the proposed equivalent-current model converts various shaped PMs into current sheets, and the actual permeability of PMs can be considered by constructing the model of modified equivalent currents to improve the accuracy of the PM equivalent-current method. Furthermore, the enhanced model can also consider the magnetic-saturation effect of machines. Finally, the electromagnetic performances of machines, such as air-gap magnetic density and back-EMF, can be predicted accurately. PM machines with various rotor core structures and PM shapes are modeled by the enhanced CM model, and the finite-element model and experiments are used to verify its universality and correctness. This model has high universality, accuracy and speed, which is of great help to the initial design and optimization of PM machines.