Abstract: In a fuel cell system, when an electric current drawn from fuel cells is controlled based on a target power generation value, an upper limit of the electric current is optimally set to make suspensions of operation caused by voltage drops to be as infrequent as possible. The upper limit of the electric current is set by adding a predetermined offset value (e.g., 2 A) to an average value of the electric current before a predetermined delay time (e.g., 10 seconds). Moreover, when the electric current drawn from the fuel cells is controlled based on a target power generation value, the value of the electric current is compared with the upper limit of the electric current, to control the electric current.

Abstract: In the fuel cell system, a change in a voltage from a cell stack in relation to a fuel utilization rate is acquired and deterioration of the cell stack is detected by comparing a value of the voltage with a reference value. Moreover, when it is determined that the cell stack has deteriorated, the rated power of the system is decreased so that the fuel cell system operates according to the deterioration state of the cell stack.

Abstract: In a fuel cell system, when an electric current drawn from fuel cells is controlled based on a target power generation value, an upper limit of the electric current is optimally set to make suspensions of operation caused by voltage drops to be as infrequent as possible. The upper limit of the electric current is set by adding a predetermined offset value (e.g., 2 A) to an average value of the electric current before a predetermined delay time (e.g., 10 seconds). Moreover, when the electric current drawn from the fuel cells is controlled based on a target power generation value, the value of the electric current is compared with the upper limit of the electric current, to control the electric current.

Abstract: The present invention provides a method for preparing a pyrochlore type oxide having a larger specific surface area, a polymer electrolyte fuel cell and a fuel cell system improved in power generation efficiency and capable of being produced more inexpensively, and a method for producing an electro catalyst for a fuel cell, which electro catalyst has a larger specific surface area, is relatively inexpensive, and has high electrode activity per unit mass. A method for preparing a pyrochlore type oxide represented by A2B2O7-Z wherein A and B represent a metal element, Z represents a number of 0 or more and 1 or less, A includes at least one selected from the group consisting of Pb, Sn, and Zn, and B includes at least one selected from the group consisting of Ru, W, Mo, Ir, Rh, Mn, Cr, and Re, wherein the pyrochlore type oxide is produced by a reaction of a halide or nitrate of A with an alkali salt of a metal acid of B.

Abstract: The present invention provides a method for preparing a pyrochlore type oxide having a larger specific surface area, a polymer electrolyte fuel cell and a fuel cell system improved in power generation efficiency and capable of being produced more inexpensively, and a method for producing an electro catalyst for a fuel cell, which electro catalyst has a larger specific surface area, is relatively inexpensive, and has high electrode activity per unit mass. A method for preparing a pyrochlore type oxide represented by A2B2O7-Z wherein A and B represent a metal element, Z represents a number of 0 or more and 1 or less, A includes at least one selected from the group consisting of Pb, Sn, and Zn, and B includes at least one selected from the group consisting of Ru, W, Mo, Ir, Rh, Mn, Cr, and Re, wherein the pyrochlore type oxide is produced by a reaction of a halide or nitrate of A with an alkali salt of a metal acid of B.