A power distribution method and system for a fuel cell vehicle is provided. The method includes deducing an amount of moisture in a stack of a fuel cell, when a supply amount of air of the stack of the fuel cell is decreased and determining a state of the fuel cell based on the amount of moisture. Additionally, the method includes deducing allowance power of a regenerative braking of a driving motor using maximum power of the regenerative braking of an air compressor and chargeable power of a high voltage battery based on the determined state. The regenerative braking of the driving motor is then adjusted to prevent actual power of the regenerative braking of the driving motor from exceeding the allowance power of the regenerative braking.

A power supply apparatus according to an example embodiment includes an abnormal state determiner configured to determine a maximum output of a fuel cell by determining whether there is an abnormality in the fuel cell, a fuel cell controller configured to control output power of the fuel cell within the maximum output based on demand power of a load, an energy storage configured to charge with power by receiving the power from the fuel cell and supply the power to the load, a charging state determiner configured to determine a charging state of the energy storage based on a charging amount of the energy storage, and a storage controller configured to control charging and discharging of the energy storage based on a difference between the demand power of the load and the output power of the fuel cell.

A controller (control portion) of a fuel cell system is provided with a flow path switching control device that switches a thermostat valve (flow path switching valve) so that, after a fuel cell has stopped generating electric power, coolant is supplied to a radiator circulation path until the coolant temperature becomes a second temperature threshold value that is lower than a first temperature threshold value.

A fuel battery system includes a fuel battery, an electric storage, a voltage adjuster, a pump, an abnormity detector, and circuitry. The fuel battery generates electricity using fuel gas and oxidant gas. The voltage adjuster is connected to at least one of the fuel battery and the electric storage. The voltage adjuster is configured to adjust voltage output from the fuel battery or the electric storage to output the adjusted voltage to a load. The pump supplies the oxidant gas to the fuel battery using electric power output from at least one of the fuel battery and the electric storage. The voltage adjuster is connected between the fuel battery and the pump. The abnormity detector detects abnormity in the voltage adjuster. The circuitry is configured to restrict the electric power supplied to the pump in a case where the abnormity detector detects the abnormity in the voltage adjuster.

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 method for starting a cold or frozen fuel cell stack as efficiently and quickly as possible in a vehicle application is based upon a state of charge of a first power source such as a high voltage battery. Power flow between the first power source and fuel cell system is coordinated in conjunction with a specific load schedule and parallel control algorithms to minimize the start time required and optimize system warm-up.

The present invention provides a method for controlling the temperature of a fuel cell system by controlling the rotational speeds of a coolant pump and a cooling fan based on the coolant outlet temperature, the amount of heat generated by a fuel cell stack, etc. In particular, the present invention controls the temperature of a fuel cell system by utilizing a controller which receives a coolant outlet temperature from a sensor in a state where a reference temperature for each stage is determined with respect to the coolant outlet temperature and a target rotational speed for each stage is determined based on the coolant outlet temperature. Then the controller performs proportional integral (PI) control with respect to each rotational speed of a coolant pump and a cooling fan at the target rotational speed for each stage determined based on the current coolant outlet temperature detected by the water temperature sensor.

A fuel cell system includes an auxiliary machine to be connected to a fuel cell, warm-up power control means for controlling generated power of the fuel cell by adjusting power supplied to the auxiliary machine during the warm-up of the fuel cell, and IV characteristic estimation means for temporarily reducing the power supplied to the auxiliary machine and estimating an IV characteristic of the fuel cell on the basis of at least two pairs of current values and voltage values at that time during the warm-up of the fuel cell.

A fuel cell has an electrolyte membrane of 5 to 10 μm in thickness. A control device for this fuel cell comprises: a controller configured to control an amount of power generation by the fuel cell according to a required amount of electric power; and a power generation reducer configured to reduce the amount of power generation by the fuel cell at a humidity of an electrolyte membrane of 95 to 98% RH to be lower than the amount of power generation at the humidity of the electrolyte membrane of lower than 95% RH.

The disclosure relates to a fuel cell system comprising a fuel cell stack for providing an electrical power P.sub.stack depending on a power demand, at least one auxiliary unit for operating the fuel cell stack with an electrical power consumption P.sub.aux, at least one consumer with an electrical power request P.sub.use, and a control unit for regulating the power demand as well as a method for controlling such a fuel cell system. It is provided that the control unit is configured to selectively operate the fuel cell system in a first operating mode or in a second operating mode, whereby the fuel cell stack is turned off depending on the operating mode upon the falling below of an optimal efficiency degree operating point P(η.sub.max) of the fuel cell system or a minimum operating point P.sub.min of the fuel cell stack. In particular, at least one auxiliary unit is also turned off in the first operating mode, when the optimal efficiency degree operating point decreases.