Embedded System of DC Motor Closed Loop Speed Control based on 8051 Microcontroller

Abstract

The objective of the present paper is designing 8051 Microcontroller based Embedded Closed Loop Speed Control System of DC Motor to study the reaction of controlled variable to set-point changes. In this present scheme a tachogenerator has been used as a speed sensor which generates a back emf corresponding to the speed attained by the DC Motor. This instantaneous value of output voltage provided by the tachogenerator is then compared with the desired voltage corresponding to the desired speed. The resulting error is used by the microcontroller to control the firing angle of the SCR for controlling the voltage applied to the DC Motor which in turn adjusts directly the motor speed to attain the desired value. Thus a continuous closed loop speed control system has been achieved. Proportional (P) Control Algorithm has been used in the present scheme. Experimental results have been presented to study the reaction of process speed with respect to set-point changes. The system is of low cost and is suitable for different industrial applications such as subway cars, trolley buses and battery operated vehicles.