| 摘要 |
PROBLEM TO BE SOLVED: To increase an electric braking force in a middle and high speed range without hardly bringing about cost increase and weight increase of a vehicle. SOLUTION: A series body composed of a brake chopper device 9 and a brake resistor is connected in parallel with a filter capacitor 8. A chopper device 14 for resistance control is connected in parallel with the brake resistor 11. A breaker 5 for the time of the voltage rise of the filter capacitor is inserted between a breaker 4 and an input terminal on non-grounding side of an inverter device 6. A reverse flow preventive diode is inserted between the junction between the brake chopper device 9 and the brake resistor 11 and the junction between the breaker and the breaker 5 for the time of voltage rise of the filter capacitor. Then, this device is provided with a voltage detector 12, which detects the voltage across the filter capacitor 8, and a controller 13 which controls the turning-on and -off of the brake chopper device 9 and the chopper device 14 for resistance control, based on the detected voltage of the voltage detector 12 and the rotational speed signal from the speed sensor 17. Hereby, this increases the electric braking force in the intermediate and high speed range, by raising the voltage between the terminals of a motor to an aerial cable voltage or higher at regenerative braking.
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