Adaptive sliding mode observer-based vector control of asynchronous motors without speed sensors

In asynchronous motor vector control systems, speed sensors are often used to measure the motor speed. Speed sensors can destroy the inherent robustness of asynchronous motors and at the same time raise the control system’s cost. This research proposes an adaptive sliding mode observer that is used in an asynchronous motor vector control system to solve these issues. Based on the mathematical model of the asynchronous motor in a two-phase stationary coordinate system, the rotor magnetic chain observer and the stator current observer are built. The sliding mode observer’s surface is made up of the difference between the observed stator current and real stator current, and as the sliding mode moves, the observed stator current value eventually converges to the real value, thus realizing the estimation of the rotor magnetic chain. The estimated rotational speed is then procured by using Lyapunov stability theory. Compared to other conventional observers, the adaptive sliding mode observer’s estimated rotational speed is more precise. At last, the simulation software MATLAB/SIMULINK is used to validate the constructed observer’s performance, and the resaults demonstrate that the observer may obtain the motor speed with a high degree of speed estimation accuracy. The observer demonstrates robustness and immunity to changes in load, motor resistance, and speed.