A FUZZY SET-THEORY BASED CONTROL OF A PHASE-CONTROLLED CONVERTER DC MACHINE DRIVE

Fuzzy logic or fuzzy set theory is recently getting increasing emphasi s in process control applications. The paper describes application of fuzzy-logic in a speed control system that uses a phase-controlled bri dge converter and a separately excited dc machine. The fuzzy control i s used to linearize the transfer characteristics of the converter in d iscontinuous conduction mode occurring at light load and/or high speed . The fuzzy control is then extended to the current and speed control loops, replacing the conventional proportional-integral (PI) control m ethod. The compensation and control algorithms have been developed in detail and verified by digital simulation of a drive system. The simul ation study indicates the superiority of fuzzy control over the conven tional control methods. Fuzzy logic seems to have a lot of promise in the applications of power electronics.