Sensorless Speed Control of Permanent Magnet DC Motor Using PI Controller

Many brushed DC motor applications require precise speed and position control, thus requiring a sensor feedback. Commonly a separate rotary encoder is required to provide speed and positional feedback to the system with additional cost. To minimize cost of drive, we required sensorless algorithm to be implemented. This report describes back EMF based closed loop control of DC motor for controlling the speed of motor. Output speed is continuously compared with set point based on back EMF measured and generated error signal is provided to PID controller. The resulting closed loop system gives linear relationship between back EMF and DC motor speed.