Patent ID: 8518590

Claim:
A fuel cell system having a fuel cell whose output characteristic has undergone a change over time, the fuel cell system comprising: a fuel cell output characteristic estimating apparatus that estimates an output characteristic of the fuel cell after the output characteristic has undergone a change over time, including a current-voltage detector that detects an output current of the fuel cell and a voltage between terminals of the fuel cell, and a controller that is configured to: estimate the output characteristic of the fuel cell after the output characteristic has undergone a change over time, the estimation being made after the output characteristic has undergone a change over time, the estimation being made on the basis of the detected output current and the detected voltage between the terminals, detected by the current-voltage detector, and a basic output characteristic of the fuel cell which is a characteristic voltage determined based on an internal resistance of the fuel cell calculated from a fuel cell temperature and a theoretical voltage based on a hydrogen supply pressure; set a target output of the fuel cell using the output characteristic of the fuel cell estimated by the controller; adjust an output of the fuel cell such that the set target output is generated by the fuel cell; and correct the basic output characteristic of the fuel cell based on the detected output current and the detected output voltage of the fuel cell; a power supply that supplies electric power to, and receives the electric power from, the fuel cell system; and a converter connected to terminals of the power supply and that transforms the voltage between the terminals of the power supply so as to be applied to the terminals of the fuel cell, wherein the controller corrects the basic output characteristic of the fuel cell by determining a voltage deviation between the detected output voltage and the characteristic voltage, and the controller sets the target output of the fuel cell on the basis of an output required to be generated by the fuel cell system, and when the set target output of the fuel cell is in excess of, or short of, the required output of the fuel cell system, the controller changes supply of the electric power to or from the power supply.