| 摘要 |
PROBLEM TO BE SOLVED: To smoothly change the main circuit voltage by providing an inverter circuit outputting the DC voltage of a capacitor as the AC voltage, and selecting a resistor circuit from multiple resistor circuits to change the resistance value in response to the detected voltage across both ends of the capacitor. SOLUTION: Electric power is fed to an induction motor 4 via an inverter 3 at the time of power running, and electric power is regenerated to the inverter 3 from the motor 4 at the time of regenerative operation. When the main circuit voltage VDC detected by a voltage detector 11 rises to the first reference voltage, the first switch 6a is turned on by the output of the first hysteresis comparator 12 a via a drive circuit 13a. The regenerative electric power determined by the resistance value of the first resistor 5a and the switch action voltage is consumed. When the voltage VDC rises to the second reference voltage, the second switch 6b is turned on by the output of the second comparator 12b, and the regenerative electric power is consumed by the parallel connection of the resistors 5a, 5b. |
