Study on harmonic suppression of permanent magnet synchronous motor with improved SHEPWM

SHEPWM (Selected Harmonic Elimination PWM, SHEPWM) is an effective modulation strategy that operates at a low switching frequency. Due to its low switching loss, it is widely used in electric propulsion systems such as new energy vehicles. Although SHEPWM can eliminate the low harmonics that significantly impact the motor, the distribution of other harmonics will be too concentrated, resulting in a series of electromagnetic noises. RSVPWM (Random Space Vector Pulse Width Modulation, RSVPWM) can disperse the centrally distributed harmonics in a specific frequency domain range. This paper adds this idea to SHEPWM, which is based on SHEPWM to achieve the random change of voltage phase in one cycle to disperse the centrally distributed harmonics, to make the harmonic distribution range wider and the peak value lower. The effects of different random number distribution laws and arrangement laws on the harmonic dispersion effect are considered. The effectiveness of the random SHEPWM (RSHEPWM) is verified by simulation.