Patent ID: 8096377

Claim:
A generator driving device comprising: a generator; an engine whose drive shaft is connected to a drive shaft of the generator; a power source capacitor that supplies power to the generator and also stores power generated by the generator; a generator inverter connected to the generator; an AC-coupled bi-directional DC - DC converter that includes two voltage source inverters whose DC terminals are connected to an additive polarity in series, and a transformer that AC-couples AC terminals of the two voltage source inverters and has a specific leak inductance, one of the two voltage source inverters being connected in parallel with the power source capacitor and supplying the inverter with a DC voltage generated by boosting a capacitor voltage of the power source capacitor; a surge absorbing condenser that is connected in parallel with the power source capacitor, has capacitance smaller than that of the power source capacitor, and at least absorbs surge; a contactor connected in series between the power source capacitor and the surge absorbing condenser; and a control unit for performing control such that the contactor is turned on after only the voltage source inverter that is not connected in parallel with the power source capacitor is activated to perform a chopping operation while the generator is operated with the contactor off, in order to control a voltage of the surge absorbing condenser so that a voltage difference between the power source capacitor and the surge absorbing condenser falls within a predetermined range.