A Full-Speed Range Hybrid PWM Strategy for High-Speed Permanent Magnet Synchronous Machine Considering Mitigation of Current Harmonics

High-speed permanent magnet synchronous machine (HSPMSM) has been widely used in high speed direct-drive applications due to its high power density and high efficiency. However, the low inductance of the HSPMSM under the condition of low carrier ratio of the motor-drive system, especially in medium and high power systems, results in high current harmonics. This paper proposes a hybrid pulse width modulation (PWM) strategy in full speed range of HSPMSM system based on a hybrid utilization of the space vector PWM (SVPWM) method and the selective harmonic elimination PWM (SHEPWM) method, in addition to having a RLC harmonic filter. The operating principle of the SHEPWM is analyzed firstly, and the structure and working principle of the system are expounded. Then, a comparison between the SHEPWM and SVPWM is carried out considering the current harmonics. Furthermore, the SHEPWM and the RLC filter are combined to achieve a better overall performance. Finally, the dynamic switching technology under different PWM methods is investigated to achieve smooth transition, and the proposed control strategy in this paper is verified by simulation results.