A fuzzy compensated microcomputer based DC drive

Fuzzy logic or fuzzy set theory is recently getting increasing emphasis in process control applications. This paper describes the application of fuzzy logic in a speed control system that uses a single phase, fully-controlled B2C converter bridge driving a separately excited DC motor. The fuzzy logic is used to linearize the transfer characteristics of the converter in discontinuous conduction mode occurring at light loads. The voltage to current ratio increases with discontinuity, which causes an improper operation of the current controller and a sluggish response of the speed controller, as both controllers are tuned in the case of continuous conduction when the ratio between voltage and current is constant. A compensation algorithm is developed in details then fuzzified. A new, fast and efficient algorithm for representing fuzzy sets in real time implementation was suggested. The fuzzy system was simulated and tuned finely to match the actual values. The overall system was verified experimentally by open loop response. The closed loop response was investigated and recorded in both cases, with and without the use of fuzzy compensation and the results were studied and compared. The experimental results (closed loop response) indicated the the befits of fuzzy logic in the field of DC drives.