Low-Speed LADRC for Permanent Magnet Synchronous Motor With High-Pass Speed Compensator

The operation of permanent magnet synchronous motors (PMSMs) is subject to many disturbances due to structural characteristics and operating situations. Particularly at low speeds, periodic disturbances, for instance, offset current error, cogging torque, etc., have a greater impact on the stable operation of the motor. For periodic disturbances, the conventional disturbance observer suffers from high delay and static error. Although the observer bandwidth can be increased to enhance the tracking ability to perturbations, this will introduce high-frequency noise at the same time. To solve these problems, an improved linear active disturbance rejection controller (LADRC) in this article is designed. By adding an error proportional feedback term to the extended state observer (ESO), the capability of the system to observe load perturbations is tremendously enhanced. A high-pass filter (HPF) is employed at the state error feedback (SEF) as a speed compensator. This method can reduce the speed of ripples feasibly without complex structures and tedious calculations. The stability of the proposed method is demonstrated by theoretical analysis, and both simulation and experimental results are given to verify the effectiveness of the proposed method.