Design and Simulation of some Controllers for Speed Control of Chopper fed DC Motor

Abstract

This paper presents a comparative study of speed control of a separately excited DC motor by using different type of controllers. Speed of separately excited DC motor can be varied below and above the rated speed by various techniques. It can be varied above rated speed by field flux control and below rated speed by terminal voltage control .Conventional controllers are commonly being used to control the speed of the DC motors in various industrial applications. It’s found to be simple, robust and highly effective when the load disturbance is small. But during high load or rapid variation of load, the fuzzy technique based controllers proves to be fast and reliable. Using chopper input voltage can be varied and thus speed can be varied. For better performance of the DC motor various kind of controller namely P-I, I-P, Fuzzy logic controller are used. Proportional-Integral type controller is used to eliminate the delay and provides fast control. However, the P-I controller has some disadvantages such as: sluggish response to a sudden load change, the high starting overshoots and sensitivity to controller gains. So, the relatively new Integral Proportional (I-P) controller is proposed to overcome the disadvantages of the P-I controller .After obtaining the model of separately excited DC motor, it is simulated using MATLAB (Simulink) environment. Then fuzzy logic controller has been designed and performance has been observed. Finally a comparative study is done between all the controllers.