<p>The issue of accuracy and convergence speed in speed control of induction motors is considered one of the important challenges that has recently attracted researchers. This paper addresses this issue and presents a hybrid control method consisting of a controller and an estimator for controlling the velocity of an induction motor. Unlike previous papers drawing on the model predictive control (MPC) tactic for controlling an induction motor’s velocity, this paper uses a fractional-order MPC for this purpose. In other words, a fractional-order cost function is used in the presented control method to increase the convergence speed and tracking accuracy. On the other hand, this paper uses a strategy to increase the control loop’s resistance to unwanted load changes. More specifically, this paper presents an extended load estimator (ELE), using which the load torque is estimated at each time constant and referred to the controller. In this way, the control law is updated at each time constant in proportion to the load and, as a result, will be resistant to sudden changes because these changes are detected by this estimator and the controller compensates for them. The productivity of the method presented in this paper was measured in a series of practical experiments in the laboratory, and the outcomes confirmed its effectiveness in increasing the convergence speed and also increasing the tracking accuracy.</p>

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A hybrid strategy including fractional model predictive control and extended load estimator for the speed control of induction motors for the accuracy and convergence enhancement

  • Chuanwu Liu,
  • Liuning Zhu

摘要

The issue of accuracy and convergence speed in speed control of induction motors is considered one of the important challenges that has recently attracted researchers. This paper addresses this issue and presents a hybrid control method consisting of a controller and an estimator for controlling the velocity of an induction motor. Unlike previous papers drawing on the model predictive control (MPC) tactic for controlling an induction motor’s velocity, this paper uses a fractional-order MPC for this purpose. In other words, a fractional-order cost function is used in the presented control method to increase the convergence speed and tracking accuracy. On the other hand, this paper uses a strategy to increase the control loop’s resistance to unwanted load changes. More specifically, this paper presents an extended load estimator (ELE), using which the load torque is estimated at each time constant and referred to the controller. In this way, the control law is updated at each time constant in proportion to the load and, as a result, will be resistant to sudden changes because these changes are detected by this estimator and the controller compensates for them. The productivity of the method presented in this paper was measured in a series of practical experiments in the laboratory, and the outcomes confirmed its effectiveness in increasing the convergence speed and also increasing the tracking accuracy.