Dynamic equations algorithm of the sensorless BLDC motor drive control with Back-EMF filtering based on dsPIC30F2010

This application note describes a sensorless Brushless Direct Current (BLDC) motor control algorithm that is implemented using dsPIC30F2010 Digital Signal Controller (DSC). The algorithm works utilizing a majority function for digitally filtering the Back-Electromotive Force (BEMF). Each phase of the motor is filtered to determine when to commutate the motor drive voltages. This control technique excludes the need for discrete, low-pass filtering hardware and off-chip comparators. It should be pointed out that all the discussions here, and the application software, assume a 3-phase motor has to be used.