Patent ID: 7541760
Filing Date: 2009-06-02
Classification: H02P

Abstract:
1. A method capable of controlling a brushless DC motor, which has a stator wound with a plurality of coils and a rotor rotating around the stator, comprising the following steps: a Hall component detecting a magnetic pole position and producing a Hall signal corresponding to said magnetic pole position; a driving unit producing a PWM signal based on an external control signal; and a switch circuit being controlled with the PWM signal and the Hall signal to switch the phase of a current outputting to the coils for driving the rotor; characterized in that the method further comprises following steps: (A) the level of the external control signal increasing or decreasing corresponding to a change of the level of the Hall signal at the time of the level of the Hall signal being detected to be switched; (B) the duty cycle of the PWM signal gradually increasing to a preset duty cycle from 0 while the level of the external control signal increasing; and (C) said duty cycle gradually decreasing to 0 from the preset duty cycle while the level of the external control signal decreasing.