| 摘要 |
PURPOSE: To constantly obtain a regular position detection point by fixing the interval of induced voltage generated in the armature winding of a brushless motor from its current-flow changed time on the basis of a comparison result of the induced voltage excluding the interval up to the beginning with a reference voltage, and masking spike voltage generated in the armature winding surely. CONSTITUTION: FF circuits 12a, 12b, 12c are set at the point of generated time of spike voltage and are reset at the point of generated time of induced voltage, and the Q outputs of the FF circuits 12a, 12b, 12c become pulses corresponding to the spike voltage. Namely, the spike voltage is surely removed from signals to be inputted to a current-flow changing signal generating part 5, since the width of the input OE signals of buffers 4a, 4b, 4c changes corresponding to the change of the waveform of the spike voltage. Accordingly, it becomes possible to obtain a regular position detection point of the rotor 1a of a brushless motor 1, in the current-flow changing signal generating part 5. As a result, it becomes possible to raise the reliability and safety of an appliance having a brushless motor 1. |
