Control of induction motor drives using modified-fuzzy logic methods

An investigation into the implementation of a PLC-based modified-fuzzy logic controller for an induction motor drive is presented. The controller consists of two control strategies i.e. a PID-type fuzzy logic controller and an incremental PID action. At the early stage of control action, the task is handled by PID-type fuzzy controller. When the absolute of error is less than a threshold value, the input of integrator at the output side is no longer given by fuzzy action but fed by incremental PID action. In other words, the controller output is no longer PI type + PD type fuzzy control but conventional PID + PD type fuzzy control. In terms of the control action, this can be seen as increasing the proportional and derivative action when the actual value is closed to reference. The controller is simulated under several conditions i.e. sudden changes in reference, sudden changes in load, and both simultaneously. The results revealed the robustness of the controller to the different type of disturbances.