A fuzzy set theory based control of a phase-controlled converter DC machine drive

Fuzzy logic or fuzzy set theory is getting increasing emphasis in process control applications. The paper describes application of fuzzy logic in a speed control system that uses a phase-controlled bridge converter and a separately excited DC machine. The fuzzy control is used to linearize the transfer characteristics of the converter in discontinuous 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 method. The compensation and control algorithms have been developed in detail and verified by digital simulation of a drive system. The simulation study indicates the superiority of fuzzy control over the conventional control methods