Patent ID: 9444113
Filing Date: 2016-09-13
CPC Classification: H01M,Y02E,Y02P,Y02T

Claim Text:
1. A fuel cell system, comprising: a fuel cell configured to receive a fuel gas and an oxygen-containing gas respectively supplied to an anode and a cathode, which are placed to face each other across an electrolyte membrane having proton conductivity, and generate electric power; a power generation controller configured to perform load-responding power generation control that controls power-generating operation of the fuel cell based on a power demand for an external load; and a secondary battery capable of charging and discharging electric power to be usable in combination with the fuel cell, as a power source to supply power to the load, wherein the power generation controller is configured such that when the fuel cell is in a performance degradation state that has potential for degradation of power generation performance of the fuel cell, the power generation controller performs water production increasing control, which shifts a power-generating operation state of the fuel cell to a state of increasing an amount of water production on the cathode compared with the load-responding power generation control, and subsequently performs water production non-increasing control, which shifts the power-generating operation state of the fuel cell to a state of reducing an increase in amount of water production compared with the water production increasing control, wherein the power generation controller is configured to oscillate between the water production increasing control and the water production non-increasing control in the performance degradation state, wherein the power generation controller is configured such that when performing the water production increasing control, the power generation controller shifts the power-generating operation state of the fuel cell to a state of an increased electric current and a decreased voltage to increase an amount of water production on the cathode, and when performing the water production non-increasing control, the power generation controller shifts the power-generating operation state of the fuel cell to a state of decreased electric current region and increased voltage region compared with the water production increasing control to suppress an increase in the amount of water production compared with the water production increasing control, and wherein the power generation controller is configured to compare the state of charge of the secondary battery and a predetermined threshold range, the threshold range becoming a low threshold range at a cell temperature in an intermediate temperature range, the threshold range becoming a high threshold range at a cell temperature in a low temperature range where the threshold range becomes higher than the low threshold range as the temperature range becomes lower than the intermediate temperature range, and the threshold range becoming a high threshold range at a cell temperature in a high temperature range where the threshold range becomes higher than the low threshold range as the temperature range becomes higher than the intermediate temperature range, and wherein the power generation controller is configured such that when the state of charge of the secondary battery exceeds the predetermined threshold range, the power generation controller determines availability of the water production increasing control.