| 摘要 |
PROBLEM TO BE SOLVED: To avoid wasting power at refresh discharge of second-battery. SOLUTION: A current from a secondary battery 14 is converted by an inverter 16 to a three-phase alternating current to drive a motor 10. One terminal of a commercial power supply 24 is connected to a neutral point of the motor 10, while the other terminal is connected to positive and negative electrodes of the secondary battery 14 through transistors 34a and 34b. When the terminal to the neutral point has a positive voltage, a transistor 32a on the positive side of the inverter 16 and the transistor 34b are turned on and off under pulse modulation control by using a control circuit 18. When the terminal has a negative voltage, a transistor 32b on the negative side of the inverter 16 and the transistor 32b are placed under pulse modulation control. In this way, the power of the secondary battery 14 is returned to the commercial power supply 24. |
