Apparatus and method for determining commutation time of sensorless brushless direct current (BLDC) motor

摘要

Disclosed is an apparatus and a method for determining a commutation time of a three phase brushless direct current (BLDC) motor. The apparatus comprises a commutation controlling pulse generation unit receiving a phase voltage of each phase and generating a commutation controlling pulse to determine a commutation time of each phase of the motor; a first counter receiving a first commutation controlling pulse output from the commutation controlling pulse generator and counting the period of commutation controlling pulses; a memory storing one half of the counted values of the period of the first commutation controlling pulses counted by the first counter; a first comparator comparing a counting value of a period of a commutation controlling pulse provided after the first commutation controlling pulse counted by the first counter with one half of the counted values of the first commutation controlling pulses stored in the memory; and an output controller receiving the comparison result of the first comparator and outputting a switching signal to control commutation of each phase of the motor. The method comprises the steps of receiving variations of the BEMF of each phase of the motor and generating commutation controlling pulses for determining a commutation time; counting the period of the commutation controlling pulses; storing one half of counted values of the counted period of the commutation controlling pulses in a memory; counting a period of the commutation controlling pulses provided after the counted commutation controlling pulses; comparing counted number of the commutation controlling pulses input during the counting operation with the value stored in the memory; and generating a switching pulse to perform commutation of each phase of the motor when the comparison results are identical.