A Microcontroller based Speed Controller for Permanent Magnet Brushless DC Motor

This paper presents a software controlled digital speed controller for Permanent Magnet Brushless DC motor. The scheme of the implemented drive system includes a position sensing mechanism, speed calculation from shaft encoder, speed controller, reference current generator, current controller, current controlled voltage source inverter and PMBL Motor. The hardware scheme developed consists of Hall effect current sensors used for the measurement of phase currents, optical isolation, driver circuit and MOSFET based Inverter. An assembly language program is written to realize PI speed controller, reference current generator, PWM current controller etc. The digitally controlled system provides high accuracy, reliability, flexibility and good system interaction and cost effective solution. The entire drive system is controlled by an intel 16b microcontroller. The drive system is simulated under real time conditions to investigate the performance of the drive under starting, reversal and load perturbation. The simulated results are compared with the experimental results. Experimental results obtained from a prototype drive are shown to confirm the validity of the simulated results.