| 摘要 |
A high power efficiency drive system for a DC motor which controls the supply of power to polyphase coils has a DC-DC switching converter for changing an output voltage according to an ON-time ratio of the switching transistor, and a switching controller for controlling the ON-time ratio of the switching transistor. The DC-DC switching converter includes a switching transistor for chopping the voltage of a DC voltage source, a filter for smoothing the output voltage of the switching transistor, and a current amplifier for supplying the switching transistor with a base current pulse having a magnitude proportional to an input current. The switching controller controls the operation of the current amplifier for producing the base current pulse of the switching transistor. The system further includes a current detector for detecting the current to the polyphase coils, a current supplier for supplying the current amplifier with the input current corresponding to the detected signal from the current detector, so that the base current of the switching transistor at the ON-time changes corresponding to the current to the polyphase coils.
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