Fuzzy logic enhanced speed control system of a VSI-fed three phase induction motor

In closed loop speed control, the speed loop error signal controls the PWM inverter frequency and voltage. The control strategy can be implemented by scalar control and vector control. Though so many researches have been carried on vector control of induction motor, scalar control is rather simple to implement and there is a lot of scope to make the control system of the induction machine robust through scalar control. A speed control with closed loop flux improves the performance of the machine under v/f control. The flux feedback signal can be estimated from machine terminal quantities as current and speed and then solving first order simultaneous differential equations. But complications arise with the numerical solution of differential equations. The numerical solution of such problem requires iterations that lead to a massive amount of communication delay. Moreover numerical solutions of machine´s differential equations need uniform and periodic sampling of line quantities that is the limitations of many data acquisition hardware. In this paper, fuzzy-mapping technique is proposed as a substitute of the conventional method in the machine control application to make the overall control efficient in real time.