When the permanent magnet assisted synchronous reluctance motor(PMaSynRM)runs at high-speed with flux-weakening control,the DC bus voltage utilization is not high,and the efficiency and torque output capacity of the motor are low. Therefore,a flux-weakening control strategy of permanent magnet assisted synchronous reluctance motor based on hexagonal trajectory was proposed. Firstly,based on the d-q axis equivalent circuit of the permanent magnet assisted synchronous reluctance motor,the voltage and current constraints of the flux-weakening process were derived,and the root cause of the flux-weakening control to improve the speed regulation ability of the motor was proved. Secondly,in order to give full play to the advantages of high-power density under high-speed operation of permanent magnet assisted synchronous reluctance motor,the over-modulation algorithm was derived. It was applied to the flux-weakening operation of permanent magnet assisted synchronous reluctance motor to achieve higher DC bus voltage utilization. Finally,the effectiveness of the proposed method was verified by simulation.

The model predictive control (MPC) with duty ratio regulation has been widely studied. However, most of the existing MPC regulates the duty ratio without considering the speed region. In this paper, the generation of torque ripple is analyzed quantitatively. Based on the cause of torque ripple, this paper performs a four quadrants correction on the duty ratio regulation. The equation for the torque variation during one inverter cycle is rewritten. The torque variation is calculated in a new perspective. The proposed method can further reduce torque ripple in the whole speed region. In specific, the effect of the proposed method in the low-speed zone is better than that in the high-speed zone. Finally, simulation results are provided to demonstrate the effectiveness of this method.

The current loop is significant for disturbance rejection performance in interior permanent magnet synchronous motor (IPMSM) drive system. This article presents a robust current model predictive control method which significantly expands the bandwidth of the current loop. The proposed method is based on an incremental model which can avoid the disturbance of inaccurate flux linkage. However, disturbance from inaccurate inductors and resistors in the motor model can also affect predictive control. To cope with this problem, the proposed method combines with an extended state observer (ESO) which is used to estimate disturbance and compensate for it. Finally, the effectiveness of the proposed method is verified in Simulink.