| 摘要 |
PURPOSE:To provide a subsidiary power supply for driving a transistor by providing a series circuit at the positive side of a single power supply for driving a control circuit operating a plurality of pairs of transistor bridges and then connecting the series circuit to the output point of the transistor bridges. CONSTITUTION:A charge current according to a DC voltage Vcc flows to capacitors 16-18 which are connected to output points U, V, and W at GND level via an electronic switch 19, a limiter resistor 12, and diodes 13-15 from a first power supply 4 and the capacitors 16-18 are charged to a voltage which is obtained by subtracting the forward voltage of the diodes 13-15 from the first power supply 4. At this time, the charge current is limited to a peak current by the limiter resistor 12. The capacitors 16-18 repeat charging/ discharging corresponding to the potential change of the output points U-W, gate amplifiers 9-11 are operated by the release of electric charge stored at the capacitors 16-18, and output transistors Q1, Q2, and Q3 at the positive side of each phase arm are properly turned on or off by receiving the control signal from a pre-driver circuit 8. |
