Nonlinear control algorithm for induction motors

The nonlinear control algorithms have been becoming one of the most important fields in the research of AC drives. In order to improve the robustness of control system, a new method for the induction motor drives is proposed by using nonlinear auto disturbance rejection controller (ADRC). This controller is mainly composed of an “extended state observer” (ESO), an input reference signal tracking differentiator (TD) and a nonlinear state error feedback (NLSEF) control law . By making of the “extended state observer” that can be used to track successfully the “extended state” of the system, it is possible to realize the “state feedback” and “model, external disturbance compensation”. Because the design of ADRC is independent of the controlled system model, this controller can manifest its adaptability and robustness not only in some operation area but also in the whole working area. To demonstrate the effectiveness of proposed scheme, the ADRC is applied to the speed control of a 2.2kW induction motor. The proposed control system has been successfully tested by means of simulations. It is shown that ADRC is robust against modeling uncertainty and measurement noise, and the dynamic performances are improved as well.