A PLC-based modified-fuzzy controller for PWM-driven induction motor drive with constant V/Hz ratio control

In this paper, a method to develop and design a fuzzy-hybrid control on an industrial controller to control speed of an induction motor and implementing a constant V/Hz ratio control is presented. Detailed discussions on the controller for a PWM-driven induction motor drive system, the system identification for the model transfer function, and the analysis on output responses and the associated manipulated variables are presented. The control objective is to provide an effective control action to sudden changes in reference speed and/or load torque. A switching type controller consisting of two control modes are devised: a PID-type fuzzy controller consisting of a PI-type and a PD-type fuzzy controller, and a conventional PID. At the early phase of the control action, the control task is handled by the PID-type fuzzy controller. At a later phase 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 the incremental PID action. In term of control action, this is an enhanced proportional and derivative action when the actual value is closed to reference. Detailed evaluations of the controller's performance based on pre-defined performance indices under several conditions are presented. The findings demonstrate the ability of the control approach to provide a viable control solution in response to the different operating conditions and requirements.

► We promote the development of PLC-based PWM-driven VVVF speed drive controller.
► We illustrate a scheme for implementing a hybrid fuzzy-PID controller on a PLC.
► We model the PLC-based VVVF drive system in MATLAB/Simulink via system ID.
► The hybrid fuzzy-PID control of VSD implementing constant V/Hz ratio is addressed.
► We reveal the PWM constant V/Hz ratio control via the experiment at low speed.