A TRANSPUTER-BASED ADAPTIVE SPEED CONTROLLER FOR AC INDUCTION-MOTOR DRIVES WITH LOAD TORQUE ESTIMATION

In this paper, we design and implement an adaptive speed controller th at can estimate load torque for ac induction motor drives employing a transputer-based parallel processing technique, The adaptive speed con troller, which precedes the held-oriented control loop, consists of a two-degree-of-freedom controller and a feedforward load-torque compens ator, The two-degree-of-freedom controller is designed by a pole-place ment technique with polynomial manipulations. Its parameters are adjus ted adaptively in terms of estimated model parameters, Estimating the model parameters entails a second-order least-squares estimator with c onstant trace to avoid estimator windup. The design of the feedforward compensator is based on an estimated load-torque model, Estimating th e load torque entails a first-order least-squares estimator with varia ble forgetting factor and covariance resetting, the purposes of which are to detect any slow or sudden changes of torque disturbance, respec tively. The resulting adaptive controller is implemented in parallel b y IMS T800-20 transputers, Experimental results demonstrate the robust ness of the proposed control method in contending with varying load an d torque disturbance.