POWER SUPPLY SYSTEM AND VOLTAGE CONTROL METHOD OF FUEL CELL

摘要

An object is to maintain the voltage of a fuel cell at a desired voltage level and suppress a voltage variation, even in the case of a low load request. A power supply system including a fuel cell causes at least part of a required electric power to be supplied from the fuel cell in an ordinary load state. In a low load state, the power supply system supplies an amount of oxygen that is required to make the voltage of the fuel cell equal to a predetermined target voltage and that is less than an amount of oxygen supplied to the fuel cell in the ordinary load state, to the fuel cell. In a first low load state, the power supply system sets the target voltage to a first target voltage and supplies oxygen to the fuel cell. After a subsequent shift to a state that the required electric power becomes higher than a predetermined reference value to cause the fuel cell to generate electric power at an output voltage that is higher than the first target voltage, in a further shift to a second low load state, the power supply system sets the target voltage to a second target voltage that is higher than the first target voltage and supplies oxygen to the fuel cell.