Current Harmonic Minimum Pulse Width Modulation for Dual Three-Phase PMSM System With 3L-NPC Inverter and Output Filter

The dual three-phase permanent magnet synchronous motor (DTP-PMSM) has wide applications in fields such as wind power generation, electric vehicles, and flywheel energy storage. Reducing the current harmonics of the DTP-PMSM is beneficial for enhancing operational efficiency, diminishing noise and vibration, and improving electromagnetic compatibility, which is of significant importance for boosting the overall performance of the system. This article focuses on the current harmonic minimum pulse width modulation (CHMPWM) for the surface-mounted DTP-PMSM with a 3L-NPC inverter and an output filter. Based on the system model, the relationship between the switching angles and the harmonic current of the motor is derived, and the mathematical model of CHMPWM is established. Furthermore, the optimal switching angles that minimize the current harmonics can be obtained by solving the established optimization problem. The proposed CHMPWM takes into account the effect of filter and motor parameters on the current harmonic characteristics, which is the main difference from the conventional CHMPWM. Simulation and experimental studies were conducted on a 1 MW/40MJ flywheel energy storage system, and the results show that compared to sine PWM and space vector PWM, the current harmonics of the proposed CHMPWM are reduced by more than 40% on average. Compared to the conventional CHMPWM, the proposed CHMPWM further reduces the current harmonics by more than 20% on average and exhibits good robustness to motor parameters.