Low-Speed Control of Arc Motor Using Kalman Observer via Acceleration-Based Disturbance Observer

This article proposes a novel speed measurement strategy for a permanent magnet arc motor (arc motor) servo system. This method improves the accuracy of a low-resolution encoder at low-speed condition through a newly developed acceleration-based disturbance observer (ADOB) combined with a Kalman observer (ADOB-KMO). A novel model-reference-adaptive inertia identification based on position signal is proposed to accurately construct the motion equation of arc motor. The method can avoid the influence of inaccurate speed on the establishment of the system equation, which is different from the traditional inertia identification strategy relying on the rotor speed. The ADOB is then used to avoid differential and quadratic differential of position signal in existing disturbance observer. In addition, the observation result of ADOB is fed forward to the current control circuit to improve the disturbance rejection performance of the system. Compared with the conventional Kalman velocity observer, ADOB is used to reduce the order of KMO, and ADOB-KMO then replaces the M/T methods to measure the rotor speed. Experiments based on an arc motor and 2500 ppr encoder verify the effectiveness of the proposed method.