| 摘要 |
PURPOSE:To make a filter circuit unnecessary and improve characteristics of an apparatus by constituting a phase control loop. CONSTITUTION:Power switched by driving transistors 10-15 is supplied to driving coils 1, 2, 3 of a brushless motor. A counter-electromotive force generated in said driving coils 1-3 is measured so that a motor phase may be decided, and a difference between said motor phase and a driving pulse phase decided via a frequency divider circuit 41 is found by a phase error detector 20. Then, the oscillation frequency and phase of a voltage controlled oscillator 40 is controlled via an error amplifier 30 so that said difference will be zero. The ON- OFF timing of the driving transistors 10-15 is controlled by the output of said voltage controlled oscillator 40 via a logical circuit 42 and a power amplifier 43. At the time when this apparatus is started, the voltage controlled oscillator 40 is controlled by the output of a starting circuit 60 via said error amplifier 30. |
