A SIMPLE FUZZY LOGIC SPEED CONTROLLER FOR A DC MOTOR FED BY SEPIC CONVERTER

Document Type : Original Article

Author

Department of Electrical Engineering, Faculty of Engineering., Minoufiya University. Egypt.

Abstract

This paper presents a closed loop speed controi of a separately excited DC motor. A cascade
combination of a diode bridge rectifier and single-ended primary inductor converter (SEPIC) is
used to feed the DC motor from an AC supply. This circuit combination offers both step-up and
step-down characteristics of the motor terminal voltage as well as an approximately sinusoidal
supply current with an improved power factor. A fuzzy logic speed controller is used to overcome
any system nonlinearity and parameter changes. Also. a wide range of both speed and load
changes with satisfactory response is obtained. Two fuzzy membership functions are used
reflecting few and simple control rules. Moreover. a genetic algorithm (GA) is used to optimally
tune the fuzzy controller parameters. Simulation results of the system are obtained by solving the
differential equations in different modes of operation. The system is laboratory implemented and
the controller is investigated using a digital signal processing board (DSPI 104). The experimental
and simulation results are verified and a correlation between both has been found. The results
confirm the relevance of the proposed configuration a- a useful rectifier that achieves sinusoidal
supply current, high power factor and motor speed regulator.

Keywords