Abstract: A control strategy for controlling how much current can be provided by a fuel cell stack to a system load during a power up-transient. When a power up-transient command is given, the control strategy limits the amount of power or current that the stack can provide to the load based on how fast an anode exhaust gas recirculation pump can meet the exhaust gas recirculation demand so that the ratio between the recirculated anode exhaust gas and the fresh hydrogen remains substantially constant. Thus, during the power up-transient, the relative humidity provided by the combination of the fresh hydrogen and the anode exhaust gas maintains the membranes in the stack at the desired humidity level. Any difference between the commanded stack power and the limited stack power during the power up-transient can be provided by a system battery.

Abstract: A control strategy for controlling how much current can be provided by a fuel cell stack to a system load during a power up-transient. When a power up-transient command is given, the control strategy limits the amount of power or current that the stack can provide to the load based on how fast an anode exhaust gas recirculation pump can meet the exhaust gas recirculation demand so that the ratio between the recirculated anode exhaust gas and the fresh hydrogen remains substantially constant. Thus, during the power up-transient, the relative humidity provided by the combination of the fresh hydrogen and the anode exhaust gas maintains the membranes in the stack at the desired humidity level. Any difference between the commanded stack power and the limited stack power during the power up-transient can be provided by a system battery.