Fuel cell system and fuel cell control method

Abstract

A fuel cell system includes a fuel cell and a supplying unit, which supplies reactive gases to the fuel cell. A control unit includes a power production effective area calculator calculates the areas of the electrodes available for power production as a power production effective area. A current density calculator which calculates a current density of the power production effective area calculated by the power production effective area calculator based on the total amount of power required by the fuel cell. A gas supply amount determiner determines the amount of reactive gas to be supplied to the fuel cell depending on the current density. A gas supply controller controls the supplying unit so as to supply the amount of reactive gas determined by the gas supply amount determiner to the fuel cell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a fuel cell system according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a cell that makes up part of a fuel cell;

FIG. 3 is a block diagram of a control unit used by the fuel cell system;

FIG. 4 is a graph illustrating a relationship between power production effective areas of electrodes and a lowest temperature of a monitored fuel cell; and

FIG. 5 is a flowchart of the fuel cell system.

Claims

1. A fuel cell system, comprising: a fuel cell, which includes a membrane, and an anode and a cathode which sandwich the membrane therebetween, wherein the fuel cell produces electric power from a reaction of reactive gases via the membrane when the reactive gases are supplied to the anode and the cathode;a supplying means for supplying the reactive gases to the fuel cell; anda controlling means for controlling the supplying means, wherein the controlling means comprises:a power production effective area estimating means for estimating areas of the electrodes available for producing power as a power production effective area;a current density calculating means for calculating a current density of the power production effective area calculated by the power production effective area estimating means based on a total power required by the fuel cell;a gas supply amount determining means for determining an amount of reactive gas to be supplied to the fuel cell based on the calculated current density; anda gas supply controlling means for controlling the supplying means to supply the amount of reactive gas determined by the gas supply amount determining means to the fuel cell.

2. The fuel cell system of claim 1, wherein the power production effective area estimating means estimates the power production effective areas of the electrodes based on a temperature of the fuel cell when a lowest temperature of the fuel cell is below a predetermined temperature which indicates that moisture contained in the electrodes has frozen.

3. The fuel cell system of claim 2, wherein the power production effective area estimating means estimates the power production effective areas based on a predetermined producing power effective area estimation map.

4. The fuel cell system of claim 2, wherein the power production effective area estimating means estimates the power production effective areas of the electrodes when the temperature of the fuel cell is below a temperature of 0° C.

5. A control method for a fuel cell, which comprises a membrane, and an anode and a cathode which sandwich the membrane therebetween, wherein the fuel cell produces electric power from a reaction of reactive gases via the membrane when the reactive gases are supplied to the anode and the cathode, the method comprising the following steps of: estimating areas of the electrodes available for producing power as a power production effective area;calculating a current density of the calculated power production effective area based on a total power required by the fuel cell;determining an amount of reactive gas to be supplied to the fuel cell based on the calculated current density; andsupplying the determined amount of reactive gas to the fuel cell.

6. The control method for a fuel cell of claim 5, wherein the estimating step estimates the producing power effective areas of the electrodes based on a temperature of the fuel cell when a predetermined lowest temperature of the fuel cell is below a temperature which indicates that moisture contained in the electrodes has frozen.

7. The control method for a fuel cell of claim 6, wherein the producing power effective areas of the electrodes are estimated using a predetermined producing power effective area estimation map.

8. The control method for a fuel cell of claim 6, wherein the producing power effective areas of the electrodes are estimated when the temperature of the fuel cell is below a temperature of 0° C.