Design and Optimization of Series-Connected Hybrid Excitation Permanent Magnet Synchronous Motor.

To address the problems that the traditional permanent magnet synchronous motor airgap flux is difficult to adjust and that the weak magnetic speed expansion ability is poor, a new series-connected hybrid excitation permanent magnet synchronous motor is proposed. A DC excitation winding is added to the rotor, allowing the excitation field generated by this winding to form a series connection with the magnetic field of the permanent magnets. The structure of this paper includes an overview of the novel rotor structure and principle of operation. For the complex rotor structure, a multi-objective genetic algorithm is used for optimization, followed by finite element analysis to compare the performance of the initial motor, the optimized motor, and the conventional motor in terms of no-load air-gap magnetism, reverse electromotive force, as well as output torque and efficiency. The magnetic load of the motor in the demagnetized state is increased from 0.2 to 0.266 compared to the unexcited state, and the magnetization capacity is improved by 33%. The output torque of the optimized motor is 252 N·m at low speed; the output torque of the conventional motor is 220 N·m; and the starting torque of the motor was improved by 14.5%. The maximum speed is increased from 10,000 rpm to 11,500 rpm, and the speed expansion capacity is enhanced by 15%. The effectiveness and feasibility of the series-connected hybrid excitation permanent magnet synchronous motor are verified. [ABSTRACT FROM AUTHOR]