Simultaneous State and Disturbances Estimation for Sensorless PMSM Control: Design and Experiments

Sensorless control for permanent magnet synchronous motor (PMSM) is drawing increasing research interest in both academia and industry. To enhance the robustness of sensorless control schemes, disturbance observers are typically designed for feedforward disturbance compensation. However, the conventional framework, which separately estimates speed/position and disturbances, may lead to system instability, particularly when disturbances significantly affect speed/position estimation performance. To address this issue, this article proposes a novel estimation-based control framework that simultaneously estimates system states and disturbances. Within this framework, two simultaneous observers are introduced. First, an augmented extended Kalman filter that extends disturbances as additional states and second, a composite extended Kalman filter integrating disturbance observer and extended Kalman filter. The feasibility and effectiveness of the proposed sensorless control schemes are validated through extensive comparative hardware experiments. Compared with the conventional separate-estimation framework, the proposed approach significantly improves speed and position-estimation accuracy under load disturbances in sensorless PMSM drives.