Patent ID: 8098039

Claim:
A generator motor driving device comprising: a generator motor; an engine that has a drive shaft linked to the generator motor; a capacitor that stores electric power generated from the generator motor, and supplies power to the generator power; a driver that is connected to the generator motor and drives the generator motor, and is supplied with the electric power generated from the generator motor; a booster that is connected in parallel to the capacitor and the driver, and boosts a capacitor voltage of the capacitor and outputs the boosted voltage to the driver; and a controller that supplies power from the capacitor to the generator motor being driven by the engine, drives the generator motor using the engine as a load, performs a rated constant current control on the generator motor and a rated constant voltage control on the booster until the capacitor voltage decreases to a first voltage, and, after the capacitor voltage decreases to the first voltage, performs the rated constant current control on the generator motor and a voltage control on the booster to maintain a predetermined ratio between the capacitor voltage and a booster output voltage to be output to the driver until the capacitor voltage decreases to a second voltage that is lower than the first voltage.