基于改进指数趋近律的感应电机滑模转速观测器研究

For the speed estimation of speed-sensorless induction motor (IMs) vector control system, the conventional exponential reaching law-based sliding mode observer (SMO) can effectively reduce system chattering. However, since there exists an equal reaching term with constant gain, the chattering problem is still inevitable. Therefore, this paper proposes an improved exponential reaching law-based sliding mode observer for speed estimation to further suppress system chattering by achieving adaptive control according to the system state. First, the estimated stator current errors were chosen as sliding mode surfaces. Then a stator current and rotor flux sliding mode observer was designed. In order to realize the adaptive control of the observer on the system state variables, a variable gain was introduced into the conventional exponential reaching law-based SMO. The gain contained the stator current estimation information of SMO. Thus, the system convergence is guaranteed, while the system chattering is attenuated. On this basis, an adaptive speed observer was constructed, and the adaptive speed law was derived by Lyapunov stability theorem. Thus, an accurate observation of motor speed is achieved. The comparison experimental results show that the proposed observer can adjust system convergence speed adaptively according to the system state, and the chattering existing in the conventional sliding mode speed observer can be effectively suppressed.