SHEPWM-Based Dead-Zone Control for PMSM under Low Switching Frequency

Nowadays, permanent magnet synchronous motor (PMSM) has attracted extensive attention because of the high power density, high torque inertia ratio, etc., but PMSM presents poor performance under low switching frequency. Selective harmonic elimination pulse width modulation (SHEPWM) can eliminate low-order harmonics precisely under the low switching frequency. In this paper, the SHEPWM strategy is used to restrain the output current harmonics of the PMSM drive system, and a dead zone-based current control strategy is proposed to improve the dynamic response of the drive system. Firstly, the exact switching angles of SHE are solved by using algebraic methods, followed by the traditional control system for PMSM based on the SHEPWM strategy is given and the problem is analyzed in detail. Then, the dead-zone-based control method for PMSM with SHEPWM is proposed, which can suppress the output oscillation of the SHEPWM modulator and guarantee the stable operation of the control system. Finally, the simulation based on the 35kW PMSM drive system is established to verify the correctness and effectiveness of the proposed method, and the simulation results prove that the PMSM drive system has a good performance in both steady-state and dynamic response based on the proposed method.