Patent ID: 6879129
Filing Date: 2005-04-12
Classification: H02P

Abstract:
1. A brushless motor control method for controlling a brushless motor provided with a stator having a number of windings and a rotor having a number of magnetic poles, comprising: a step of detecting a supplied DC voltage, a step of detecting an induced voltage appearing at a terminal of an OFF phase, a step of generating an induced voltage reference value depending on the operation state of said brushless motor, a step of renewing an induced voltage change rate generation table on the basis of a change rate of said induced voltage detected at least at two points, a step of generating the change rate of said induced voltage depending on the operation state of said brushless motor on the basis of the renewed induced voltage change rate generation table, a step of detecting an intersection time of the intersection of said detected induced voltage and said induced voltage reference value on the basis of said detected induced voltage and said induced voltage reference value, or calculating said intersection time on the basis of said detected induced voltage, said induced voltage reference value and said induced voltage change rate, a step of calculating the rotation speed of said brushless motor on the basis of time interval of said detected intersection time values, a step of outputting a duty factor index on the basis of a deviation between a command speed and said rotation speed of said brushless motor, and a step of driving said brushless motor on the basis of said detected intersection time, said rotation speed and said duty factor index.