A High Performance Speed Regulator Design for AC Machines

Proportional Integral controllers tuned using classical methods may exhibit poor performance under external disturbances or sudden load changes. Fractional Order Proportional Integral (FO-PI) controllers are expected to perform better in terms of load disturbance rejection due to their Iso-damping property. This paper investigates the potential of an FO-PI controller for the speed control of an indirect field oriented (IFO) induction motor drive system with cascaded current control. The motor is first approximated with a first order plus dead time (FPDT) model and consequently an optimal FO-PI controller is designed. The FO-PI controller is implemented in both simulation and experimentation and shows better performance than its integer order counterparts.