A tunable fuzzy logic controller for chopper-fed separately excited DC motor drives

The paper presents a novel online tunable fuzzy logic controller (FLC) for the speed regulation of separately excited DC motor drives. FLC structure is implemented with linguistic classifications using a hybrid input of motor speed and current errors. The membership grade has been scaled (weighted) by a tuning factor in the defuzzifier stage of the FLC structure. The weighting factor is determined using a dynamic online rule-based scaling criteria of minimum speed excursion. In the defuzzification output stage, a modified "weighted center of area" technique is use to produce a crisp effective output to control the duty cycle ratio of the DC-DC chopper. The paper presents dynamic simulation results for a separately excited DC motor fed from a PWM DC-DC chopper. These results are obtained using the tunable fuzzy logic controller with an online adaptive variable defuzzifier structure and give good dynamic and robust response with minimum inrush motor current.<<ETX>>