Speed Sensorless Control of Asynchronous Motors Using Sliding Mode Observer with an adaptive power-order reaching law

This paper proposes an adaptive power-order reaching law sliding mode observer (APORLSMO) based on a novel nonlinear integral sliding surface for speed and rotor flux estimation in sensorless vector control of induction motors. Firstly, a rotor flux observer based on the new type of nonlinear integral sliding surface is designed in the coordinate system. Secondly, the stability of the observer is proven using the Lyapunov theorem, and by combining adaptive sliding mode reaching law, precise motor speed control is achieved. Finally, simulation results demonstrate the effectiveness of the proposed method. Compared to existing observers, this observer combines the smoothness of power-order reaching law and the fast convergence of constant-order reaching law, resolving the contradiction between the fast reaching of sliding surface required for transient performance and the large chattering after fast reaching. Additionally, it adapts well to changes in sliding surface and system states.