A vehicle includes first and second fuel-cell stacks, a first coolant circuit having conduit arranged to circulate coolant through the first fuel-cell stack, a second coolant circuit having conduit arranged to circulate coolant through the second fuel-cell stack, a heater in fluid communication with at least the first coolant circuit, and an isolation valve assembly configured to proportion a flow of coolant between the first and second coolant circuits. The isolation valve assembly includes valving. The valving has an isolation position in which the first and second circuits are isolated. The valving also has at least one mixing position in which the first and second circuits are in fluid communication.

A fuel cell system includes a fuel cell generator, a rechargeable energy storage circuit, an auxiliary load, a converter circuit, and a switch circuit. The fuel cell generator is operable to generate electrical power in a stack output signal. The auxiliary load is powered by the rechargeable energy storage circuit while in a first mode, and powered by a local signal while in a second mode. The converter circuit is operable to convert the stack output signal into a plurality of recharge signals while in the first mode and in the second mode, and convert the stack output signal into the local signal while in the second mode. The switch circuit is operable switch the plurality of recharge signals to one or more electric vehicles, and switch the local signal to the auxiliary load while in the second mode.

According to an embodiment, a power supply control system includes a state acquirer configured to acquire states of a plurality of fuel cell systems mounted in an electric device that operates using electric power, a power acquirer configured to acquire a required amount of electric power from the electric device, and a power generation controller configured to control power generation of one or more fuel cell systems among the plurality of fuel cell systems so that the required amount of electric power acquired by the power acquirer is satisfied on the basis of the state of each of the plurality of fuel cell systems acquired by the state acquirer.

A fuel cell system includes a fuel cell stack that generates electricity using fuel and oxidant gases, a reformer that produces the fuel gas by reforming a raw material, a raw material feeder that supplies the raw material to the reformer, a combustor that combusts anode off-gas discharged from the anode of the fuel cell stack, and a controller that controls the raw material feeder. The period of a load-following operation in which the power output of the fuel cell stack shifts from a lower level to a higher level, is divided into multiple sub-periods. For each sub-period, a ratio is determined from the increase amounts in the flow rate of the raw material during the sub-period and the length of the sub-period. The controller controls the raw material feeder to make a ratio on the higher output side smaller than another on the lower output side.

A fuel cell system including a fuel cell, an air compressor that supplies oxidant gas to the fuel cell, an upstream supply pipe provided with the air compressor, a downstream supply pipe connected to the upstream supply pipe and the fuel cell, an upstream discharge pipe connected to the fuel cell, a downstream discharge pipe connected to the upstream discharge pipe, a bypass pipe, a valve mechanism configured to be switchable between a supply state and a bypass state, and a controller configured to control the air compressor, the valve mechanism, and a power generation state of the fuel cell.

During performance of low efficiency power generation, a control device controls the flow rate of feed of the oxidizing agent gas so that the amount of heat generation of the fuel cell accompanying power generation loss becomes a first amount of heat generation when the state of a mount on which the fuel cell system is mounted is a first mode and controls the flow rate of feed of the oxidizing agent gas so that the amount of heat generation becomes a second amount of heat generation smaller than the first amount of heat generation when the state of the mount is a second mode where the generated electric power of the fuel cell fluctuates more easily compared with the first mode.

The control device is configured so that when a temperature of the fuel cell at the time of start of power generation of the fuel cell is less than a standard temperature, it makes the fuel cell generate power so that the amount of heat generation of the fuel cell accompanying the power generation loss becomes a first amount of heat generation and so that when a cumulative value of current of a time period during which the fuel cell is made to generate power so that the amount of heat generation becomes the first amount of heat generation is equal to or greater than a predetermined cumulative value, it makes the fuel cell generate power so that the amount of heat generation becomes a second amount of heat generation larger than the first amount of heat generation.

The control device is provided with a power generation part configured to be able to selectively perform normal power generation and low efficiency power generation in which the power generation loss is greater compared with normal power generation when there is a request for warmup of the fuel cell. The power generation part temporarily stops the low efficiency power generation and performs normal power generation when during performance of the low efficiency power generation the target generated electric power of the fuel cell becomes equal to or greater than a predetermined first switching electric power.

A control system and a control method of fuel cell stacks are provided. The control system includes a set of fuel cell stacks, a secondary battery, a monitoring device, and a control device. Each fuel cell stack has a power output that can be independently started up or shut down. The secondary battery is connected to power output terminals of the fuel cell stacks via a power transmission path. The monitoring device is configured to monitor an electrical parameter of the power transmission path. The control device receives an electrical parameter signal from the monitoring device, and outputs a control signal to shut down or start up the power output of at least one of the fuel cell stacks if the electrical parameter's value is higher than a predetermined upper limit or lower than a predetermined lower limit.

A fuel cell system includes: a fuel cell unit including first to nth fuel cells connected in series to each other to supply electric power to a load device; first to nth supply systems that independently supply cathode gas to the first to nth fuel cells, respectively; a switching device capable of switching a state between a connected state and a disconnected state; and a control unit, when required output to the fuel cell unit is equal to or smaller than a threshold value, configured to control the switching device to switch the state from the connected state to the disconnected state, and to control the first to nth supply systems to respectively control the first to nth fuel cells so as to respectively control flow rates of the cathode gas to be supplied to the first to nth fuel cells.