Research on Sensorless Control of Permanent Magnet Synchronous Motors Based on a Gain-Adaptive Sliding Mode Observer

To solve the problems associated with conventional sliding mode observers, such as high-frequency chattering, phase delay, and sensitivity to the noise of the arctangent function, we propose a novel sliding mode adaptive gain strategy and apply it to an ultra-twisted sliding mode structure. The proposed adaptive gain can be dynamically adjusted according to the rotational speed, which can effectively reduce the chattering at low speeds and enhance the stability at high speeds. As a result, the estimation accuracies of both rotational speed and rotor position are significantly improved. In addition, the stability of its application in the super-twisted sliding mode structure is analyzed. Simulation results show that the improved control system can reduce the speed error by 56.63 %, while exhibiting excellent speed tracking performance and stability.