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Cogging Torque Optimization of Permanent Magnet Direct-driven Wind Turbine Generator

In order to improve the operation performance of 6-pole 72 slot permanent magnet direct-drive wind turbine, a method of reducing cogging torque by combining magnet segmentation with rotor auxiliary slot is proposed. According to the analytical formula and superposition principle of cogging torque, the effectiveness of magnetic pole block and rotor auxiliary slot on reducing cogging torque is analyzed. Based on Maxwell finite element software, the influence of the number of permanent magnet pole blocks and rotor slotting on cogging torque is studied, and the optimal number of magnetic pole blocks and the pole arc angle of the auxiliary circle of rotor slotting are obtained. By comparing and analyzing the simulation results of the motor before and after optimization, it can be seen that the cogging torque of the motor has been significantly reduced, and the sinusoidal characteristics of the air-gap flux density and the phase no-load back EMF are also improved.