Patent ID: 6534938
Filing Date: 2003-03-18
Classification: H02P

Abstract:
A method for controlling a sensorless BLDC motor with a plurality of windings noted with a plurality of phase numbers and operated at PWM chopping mode to perform a series of sequential commutations, wherein the motor has an inverter with a plurality of high-side and low-side half bridge and a zero-crossing detection circuit, the method comprising the steps of:detecting a falling edge in a plurality of rotor position signals generated from the BEMF zero crossing detection circuit; recording the incident time and the corresponding phase number when a falling edge in the rotor position signals being detected, calculating all the delay values for the sequential commutations, and setting the time points for the sequential commutations for the high-side and low-side half bridge in the inverter respectively; determining whether the time has reached the time point for the high-side commutation; performing the high-side commutation to switch current on a pair of windings to a new pair of windings when the current time reaches the time point for the high-side commutation; determining whether the current time has reached the time points for the low-side commutation; and performing the low-side commutation to switch current to a pair of windings to a new pair of windings when the current time reaches the time point for the low-side commutation.