关键词: 永磁同步电机；随机开关频率；谐波抑制

Abstract: As the vehicle permanent magnet synchronous motor (PMSM) vector control space vector pulse width modulation (SVPWM) adopts a fixed switching frequency, its nonlinear characteristics will produce high frequency harmonics near the switching frequency and its integer multiple, increase torque ripple and electromagnetic noise, and cause electromagnetic interference in serious cases. This paper describes the basic working principle of SVPWM, and deduces the expression of high frequency harmonics generated by the non-linearity of the switching components. After that, the working principle of random switching frequency control and three kinds of pseudo random number generation methods are introduced. For the random switching frequency, its spectrum law cannot be directly discussed, so its power spectrum expression is deduced, on this basis, a vector control model based on random switching frequency is established. Based on the simulation results, the suppression effect of random PWM algorithm based on three pseudo random number generation strategies on line voltage, phase current and high frequency harmonics of phase voltage generated during PMSM operation is studied.

Key words: permanent magnet synchronous motor; random switching frequency; harmonic suppression