Optimization and Pole-Slot Analysis of a New Type Permanent Magnet Hybrid Pole Motor for Electric Vehicles

To reduce the use of rare earth materials and improve the performance of the motor, a new hybrid pole structure is proposed. The equivalent air-gap magnetic density model is established, and the N-th harmonic analytical expression of the air-gap magnetic density under the hybrid pole is derived; The optimal parameters of the hybrid pole structure are obtained by using sensitivity analysis to stratify the optimized parameters, using a mixture of Box-Behnken Design (BBD) method and Multi-Objective Genetic Algorithm-II (MOGA-II) for the first level parameters, and Central Composite Design (CCD) method for the second level parameters. The electromagnetic performance of the motor under different slots was analyzed based on the finite element method, and the results showed that the cogging torque and the no-load back electromotive force total harmonic distortion of the 48-slot compared to the 12-slot motor under the hybrid pole structure decreased by 45.2 and 47.3%, respectively. At the same time, the hybrid pole structure uses 19% less-rare-earth compared to the conventional structure.