| 摘要 |
PURPOSE:To stably and effectively drive in full-wave a brushless DC motor and to prevent the oversaturation of a drive transistor by controlling the energizing time operating state of the second drive transistor group so that the operating voltage at the energizing time of the first drive transistor group becomes the prescribed value. CONSTITUTION:The first feedback loop (current feedback loop) is composed of a current controller 21, the first selector 22, the first drive transistors 5-7, a coil current detecting resistor 26, and a resistor 27, and is operated so that a coil current detection signal Va is equalized to a command signal V1. The second feedback loop is composed of an operation detector 41, the second selector 61, and the second drive transistors 8-10, and the energizing time operating voltage detection signal V4 of the first drive transistor is equalized to the reference voltage V2. The output signal 71 of the speed detector 70 at the motor starting time is small, but the coil supply current Ia is corrected in response to the command signal V1 in response to the signal 71 and the output current i7 of the detector 41, thereby preventing the oversaturation of the first drive transistors 5-7. |
