Abstract: A control device of a fuel cell system determines opening-closing abnormality of a first valve and a second valve based on a comparison between a first pressure decrease rate and a second pressure decrease rate, the first pressure decrease rate being a decrease rate of a pressure detection value of a pressure sensor when a first control is executed, the first control being a control in which the first valve is opened in a state where the second valve is closed, the second pressure decrease rate being a decrease rate of the pressure detection value of the pressure sensor when a second control is executed, the second control being a control in which the second valve is opened in a state where the first valve is closed.

Abstract: A supply path of hydrogen gas in a fuel cell system connects a plurality of fuel cell stacks in series with each other. The supply path includes a downstream supply path configured to supply the fuel cell stack on a downstream side with exhaust gas of hydrogen gas supplied to the fuel cell stack on an upstream side, without circulating the exhaust gas to the fuel cell stack on the upstream side, and a circulating path configured to circulate exhaust gas from the fuel cell stack on the downstream side to the fuel cell stack on the downstream side.

Abstract: A fuel cell system includes a controller configured to control opening and closing of a drain valve and opening and closing of an exhaust valve. The controller is configured to, when an amount of water stored in a gas-liquid separator is larger than or equal to a predetermined value, open the drain valve to drain, via the drain valve, the water stored in the gas-liquid separator. The controller is configured to, when a concentration of impurities contained in circulating gas is higher than or equal to a predetermined value, open the exhaust valve to release, via the exhaust valve, the circulating gas circulating in the circulating path.

Abstract: It is a power source in which a plurality of fuel cell systems and one boost converter are connected in series and output power according to the required power. Among the plurality of fuel cell systems, the first fuel cell system generates electricity using a power command obtained by dividing the required power by the number of the plurality of fuel cell systems, and the other fuel cell systems except the first fuel cell system Electricity is generated using a current command having the same current value as the output current of the first fuel cell system.

Abstract: An FC system disclosed herein comprise FC units, a cooler and a controller. Each of the FC units comprises a FC stack, a supply/a return/a circulating passages through which refrigerant flows and first to third temperature sensors. The first to third temperature sensors measure temperatures of the refrigerant in the passages at different positions. The controller is configured to stop a specific FC unit, compare measured values of the first to third temperature sensors of the stopped specific FC unit and, when one of the measured values differs from the other two of the measured values, provide notification about malfunction of the temperature sensor with the different measured value.

Abstract: A controller of a FC system disclosed herein may be configured to: (1) start both of first and second FC stacks when a measured value of a gas sensor is lower than a first concentration: (2) maintain both of the first and second FC stacks stopped when the measured value is higher than a second concentration which is higher than the first concentration; and (3) when the measured value is from the first concentration to the second concentration, supply the fuel gas to the first FC stack while maintaining supply of the fuel gas to the second FC stack stopped, thereafter stop supply of the fuel gas to the first FC stack when a pressure in the first FC stack reaches a pressure threshold, and thereafter start the first FC stack when the pressure in the first FC stack after a predetermined time is higher than a pressure lower limit.

Abstract: An FC system disclosed herein comprise FC units, a cooler and a controller. Each of the FC units comprises a FC stack, a supply/a return/a circulating passages through which refrigerant flows and first to third temperature sensors. The first to third temperature sensors measure temperatures of the refrigerant in the passages at different positions. The controller is configured to stop a specific FC unit, compare measured values of the first to third temperature sensors of the stopped specific FC unit and, when one of the measured values differs from the other two of the measured values, provide notification about malfunction of the temperature sensor with the different measured value.

Abstract: An FC system disclosed herein may comprise a plurality of FC units, a cooler, and a controller. Each of the FC units may comprise a FC stack, a supply passage / a return passage / a circulating passage through which refrigerant passes, and first temperature sensor. The supply passage supplies the refrigerant from the cooler to the FC stack. The return passage returns the refrigerant to the cooler. The circulating passage is connected to the supply passage and the return passage. The first temperature sensor is configured to measure a temperature of the refrigerant in the supply passage at a position upstream of a merging point of the supply passage and the circulating passage. When measured values of the first temperature sensors of the plurality of the FC units do not match, the controller is configured to provide notification about malfunction of the first temperature sensor.