Speed Control of DC Motor Using Fuzzy Logic

Abstract

As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality. When it comes to solving real-world problem uncertainty in the system becomes inevitable, this is where fuzzy logic comes into action. A Fuzzy tool is a mathematical tool that deals with uncertainty around us making Fuzzy system to be a system that takes in imprecise data and vague statements which is all the information we need and produces an output as a decision with a compromise of the amount of uncertainty we are willing to accept. In this paper, the speed of a DC shunt motor is controlled using the fuzzy logic technique. Under unavailability of motor and load parameters, an absolute speed trajectory control can be achieved. This control scheme fetches a very acceptable result in short time. The Fuzzy method adopts a human-like intuition to the control strategy and is self-tolerant to inputs which are not so precise It is very efficient where the precision required is not too high. It is a robust, easily controllable strategy. It is capable of realizing multiple inputs and producing different numerous outputs. Hence, the discussed strategy is used to achieve flexible control of the speed of the Separately Excited DC Motor. Error in speed and the derivative of Error are taken as the inputs to the Fuzzy controller and by selecting suitable membership functions the output of the fuzzy controller changes the duty cycle of a switching device which then controls the supply voltage to the armature. In this way, the speed of the DC motor is controlled by regulating the armature supply voltage.

Keywords: Fuzzy Logic Controller, Pulse Width Modulation, Speed Control of Dc motor