DRIVE DEVICE FOR A BRUSHLESS MOTOR

摘要

PCT No. PCT/JP88/01169 Sec. 371 Date Jul. 19, 1989 Sec. 102(e) Date Jul. 19, 1989 PCT Filed Nov. 18, 1988 PCT Pub. No. WO89/05061 PCT Pub. Date Jun. 1, 1989.A brushless motor driving device includes a plurality of motor driving coils and a plurality of driving transistors, coupled to the motor driving coils, for periodically supplying an electric power to the motor driving coils. A power supply switching circuit is provided for generating a power supply switching signal for driving the motor driving coils on the basis of a frequency signal corresponding to an oscillation frequency of a voltage controlled oscillator. A phase difference detector is provided for detecting a difference between the power supply switching signal and a counterelectromotive voltage generated in the motor driving coils during a period in which no electric power is supplied to the motor driving coils. The phase difference detected by the phase different detector circuit is used to control the oscillation frequency of the voltage controlled oscillator.