Complex vector decoupling and Delay compensation for PMSM at Low Carrier Ratio

PI current controller based on synchronous reference frame has been widely used in industry. It has high reliability and easy to use. However, when the permanent magnet synchronous motor(PMSM) operates at a higher speed, the ratio of the inverter switching frequency to the motor operating frequency(carrier ratio) is low, which intensifies the coupling between the $d$-axis current and the $q$-axis current of the PMSM. This will cause the current to oscillation, and even lead to the current out of control. In this paper, the complex vector decoupling method is used to control the motor current, which improves the current coupling and the dynamic performance of the system. In addition, the low carrier ratio will also aggravate the delay problem in the drive system. This paper analyzes this problem and adopts the phase compensation to solve it. Simulation and experiment verify the effectiveness of the proposed method.