A nonlinear auto-disturbance rejection controller for induction motor

The nonlinear control algorithms have been becoming one of the most important fields in the research of AC drives. This paper proposes a new method for induction motor drives by using a nonlinear auto-disturbance rejection controller (ADRC). The ADRC is independent of the mathematical expression of the object. 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 an “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”. Via the use of ADRC, the stability is guaranteed for the speed servo control and the insensitivity to uncertainties and disturbances is obtained as well. To demonstrate the effectiveness of proposed scheme, the ADRC is applied to the speed control of a 2.2 kW 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