Automatic phase adjuster for a brushless motor driving signal

Abstract

An automatic phase adjuster for the driver of a brushless motor is provided. This automatic phase adjuster can output a driving signal adaptively with a suitable phase-lead or phase-lag angle so as to allow the motor to be operated with the optimal output characteristics, including optimal output torque, optimal output efficiency, and optimal output power at all speeds. The automatic phase adjuster is configured variously in accordance with the particular type of the motor on which the automatic phase adjuster is used. For single-direction motors operated at a fixed speed, the automatic phase adjuster includes a phase-lead filter coupled to a Hall sensor which detects the motor speed. For single-direction motors operated at various speeds, the automatic phase adjuster includes a phase-lead filter, a phase-lag filter, a multiplexer, and a Hall sensor. The multiplexer selects either the phase-lead filter or the phase-lag filter to process the motor speed signal. For dual-direction motors operated at various speeds, the automatic phase adjuster includes a phase-lead filter, a phase-lag filter, a multiplexer, and a Hall sensor. The multiplexer selects either the phase-lead filter or the phase-lag filter depending on the direction and acceleration/deceleration condition of the motor. This allows the motor to be always driven with optimal performance.