The Research Of Field-Oriented Induction Motor Drive System Based On Active Disturbance Rejection Controller

The field oriented control technique is widely used in high performance motion control of induction motors. However, in real-time implementation, precise decoupling which requires accurate motor parameter can't be fully realized due to significant plant uncertainties such as external disturbances, parameter variations and plant nonlinear dynamics. This may deteriorate the dynamic performances of flux and torque significantly.In order to obtain high performance induction motor drive systems, Active Disturbances Rejection Control (ADRC) for a field-oriented induction motor drive system is proposed in this dissertation, in which he close-loop controllers,the rotor flux observer and the speed identification t are three dominant parts.The dynamic performance of a FOC system depends on its speed and current loop controllers. While same dynamic performance is kept ,ADRC technology is introduced into the controller design to deal with the influences of the unknown external disturbances and the coupling items in speed and current models, the first-order ADRC model is simplified and its computation load is reduced, thus the practicability of ADRC is greatly enhanced .Rotor flux observation is a key step in implementation of a field-oriented control (FOC) system. In order to reject the influence of rotor resistance perturbation, a new rotor flux observer based on an Extended State Observer (ESO) with model compensation is proposed. The perturbation of rotor resistance is taken as a system model disturbance, which can be observed and compensated by ESO. As a result, the performance of rotor flux observer based on ESO compensation is improved to a great degree.For the implementation of sensorless FOC, a speed identification algorithm is introduced on the basis of ESO. By means of the existing structure of ADRC system, speed information is picked up from the observation results of the unknown model in ESO.The simulation and experiment results show that the controller ensures very good robustness and adaptability under modeling uncertainty and external disturbance, and it is concluded that the proposed controller produces better dynamic performance such as small overshoot and fast transient time than conventional PID controller in the overall operating conditions.