Sensorless Speed Control of PMDC Motor with Cascade PI Controller

In this paper, the cascade control scheme for the speed and current control of permanent magnet DC (PMDC) motor is presented without any sensor where the inner loop is to adjust the armature current and the outer loop is to control the speed of the motor. Thus, while overall system cost, maintenance and complexity are reduced, the reliability and robustness of system is improved. Moreover, the importance of current control is demonstrated by means of the settling time to steady-state and life cycle of PMDC motor and its driver circuit. The control algorithm is realized by using LPC1768 microcontroller.