Sensorless control of a BLDC motor with back EMF detection method using DSPIC

This paper proposes a scheme for sensorless control of a brushless dc (BLDC) motor by direct back EMF detection method using dsPIC30F3010. A mathematical model of the drive system is simulated with MATLAB SIMULINK Toolbox and the reference design incorporates both hardware and software parts of the system. The simulated and experimental results from a prototype BLDC drive system are verified. Experimental waveforms of phase back EMF, current and speed obtained from a 3-phase, 120 W, 4-pole, BLDC drive system are validated with simulation results. As the terminal voltage of the motor is proportional to the phase back EMF on the floating phase, the DSP-ADC feature utilized to sense the back EMF proved the validity of sensorless control over a wide speed range.