| 摘要 |
PURPOSE:To efficiently operate a brushless motor by applying a pulse having a duty ratio proportional to the speed deviation signal to the input of one complementary transistor to which a current from a stator coil is flowed, thereby preventing the through phenomenon. CONSTITUTION:When the outputs of magnetic detectors 1, 2 are respectively L and H, transistors TR14, 25 of complementary amplifiers 4, 5 of output terminal are ON, while transistors TR15, 24 are OFF. Thus, a current from a power source VCC flows in a circuit of the TR14, the stator coil 7-1, the TR25 and a ground terminal G. In the amplifier 4, the TR15 is OFF with constant resistance. Even if a rectangular pulse is applied to the base of a modulation transistor TR 16, no through phenomenon occurs. In the amplifier 5, the TR24 is OFF, and the power voltage VCC is constant. Accordingly, no through phenomenon occurs. The TR25 is modulated with the rectangular pulse from a speed control circuit 10 via the modulating TR26, and the duty ratio of the rectangular pulse is controlled by the current of the stator coil 7-1. |
