Simulation studies of optimized classical direct torque fuzzy controlled drive for permanent magnet synchronous motor

In this paper, a fuzzy logic based direct torque control (DTC) scheme with optimum number of input membership functions and fuzzy inference rules is presented. The proposed direct torque fuzzy control (DTFC) algorithm is based on classical DTC while the hysteresis controllers are replaced with a single Mamdani type of fuzzy controller. As a result of such a modification, considerable flux and torque ripple reduction as well as much lower current distortion is attained, while the perfect dynamic response of classical schemes is still maintained. In fact, the obtained improvements are mainly due to linguistic nature of reasoning provided by fuzzy controller which enables more appropriate voltage vectors to be chosen for the pertaining flux and torque error values. In terms of assigned input membership functions, zero voltage vectors capability is considered yet the unnecessary algorithm complexity is avoided. As far as fuzzy inference system is concerned, the proposed controller employs less fuzzy rules compared to other classical DTFCs, which also enables lower implementation cost. The performance of such a drive is evaluated in terms of both steady state and dynamic response by means of comparative simulation study.