A fuel cell system and the method of controlling the fuel cell system improve next-time startability in the following manner. Hydrogen, air, generation water, and the like that remain inside a large-sized fuel cell system needs to be removed after finishing operation of the large-sized fuel cell system, such as a fuel cell system for generating electric power. To the present end, when an air compressor needs to be operated, one fuel cell module is selected as a power supply module, and an air compressor is operated by the power supply module. Thus, durability of a fuel cell stack is improved, and at the same time, a constant amount of generated electricity necessary to restart the large-sized fuel cell system is ensured.

A fuel cell system includes a plurality of fuel cells and a control device that controls an operation state of each fuel cell. The control device has a command receiver that acquires an output command showing a total output power which should be generated by the fuel cell system, a first determiner that determines the number of fuel cells which should be operated in the normal operation mode, and an operation state manager that determines the operation state of each fuel cell. Based on the output command, the operation state manager changes the operation state of at least one of the fuel cells which are being operated in the normal operation mode to the standby operation mode, or changes the operation state of at least one of the fuel cells which are being operated in the standby operation mode to the normal operation mode.

A fuel cell system includes a plurality of fuel cells and a control device that controls an operation state of each fuel cell. The control device has a command receiver that acquires an output command showing a total output power which should be generated by the fuel cell system, a first determiner that determines the number of fuel cells which should be operated in the normal operation mode, and an operation state manager that determines the operation state of each fuel cell. Based on the output command, the operation state manager changes the operation state of at least one of the fuel cells which are being operated in the normal operation mode to the standby operation mode, or changes the operation state of at least one of the fuel cells which are being operated in the standby operation mode to the normal operation mode.

An illustrative example fuel cell reactant flow control valve assembly includes a pneumatic valve configured to allow reactant flow when the pneumatic valve is in an open condition and to prevent reactant flow when the pneumatic valve is in a closed condition. A control valve selectively allows a pressure of the reactant to provide pneumatic pressure to maintain the pneumatic valve in the open condition. The control valve selectively vents the pneumatic pressure reservoir to control a rate at which the pneumatic pressure decreases and a rate at which the pneumatic valve changes from the open condition to the closed condition.

A system for estimating a concentration of hydrogen in a fuel cell is provided. The system includes a hydrogen supply line supplying the hydrogen to the fuel cell and a time measurement sensor measuring a time duration from a point in time when an operation of the fuel cell ends to a point in time when the fuel cell restarts. A controller estimates an amount of air introduced into the fuel cell during the time duration using the measured time duration and estimates a concentration of hydrogen in the hydrogen supply line at the time of restarting the fuel cell based on the measured time duration and the estimated amount of introduced air.

A fuel cell control method, control system and electric vehicle. The control method comprises the following steps of determining that the fuel cell is shut down and controlling the fuel cell to enter a standby mode, wherein the standby mode comprises the step of controlling the electric quantity output by the stack module of the fuel cell such that it is used only for maintaining the working temperature of the fuel cell. From the above content, it can be known that according to the technical solution provided by the invention, the low-power consumption standby operation of the fuel cell can be maintained, the temperature of the fuel cell is ensured to be at the working temperature, the heat loss caused by the shutdown of the fuel cell is reduced, the power requirement of a whole vehicle is met in an instant response manner when the fuel cell is started for the second time, the starting time is short, the gas loss and the starting time caused by heating the fuel cell during the second starting are reduced, and the fuel cell does not need to be heated during the second starting, so that the rotating speed of a fan does not need to be increased, and the comfort of the electric vehicle is ensured.

A fuel cell power system that includes multiple strings that each have multiple sub-stacks of fuel cells. Each sub-stack is electrically isolated from other sub-stacks and each sub-stack can be independently controlled by a DC control module on a printed circuit board. The DC control module of a sub-stack can regulate or shut off the output power of the sub-stack if the sub-stack becomes weak or fails. A sub-stack can be shut off while other sub-stacks in the system continue to operate. The output power of other sub-stacks can be increased to compensate for sub-stacks that are shut down.

A fuel cell power system that includes multiple strings that each have multiple sub-stacks of fuel cells. Each sub-stack is electrically isolated from other sub-stacks and each sub-stack can be independently controlled by a DC control module on a printed circuit board. The DC control module of a sub-stack can regulate or shut off the output power of the sub-stack if the sub-stack becomes weak or fails. A sub-stack can be shut off while other sub-stacks in the system continue to operate. The output power of other sub-stacks can be increased to compensate for sub-stacks that are shut down.

To provide an electrical power system and an electrical power control device that make it possible to improve fuel efficiency compared to that conventionally possible. An electrical power system according to an embodiment includes fuel cells at a count of n, n representing an integer of 2 or greater, and a controller. The fuel cells are each configured to generate electrical power through electrochemical reactions. The controller is configured to set, based on a required output required in accordance with electrical power to be consumed by a load, an operation mode for each of the fuel cells to one mode determined from a plurality of modes including a first electrical power generation mode under which starting and stopping of generation of electrical power are repeated, a second electrical power generation mode under which generation of electrical power continues, and a stop mode under which generation of electrical power is stopped.

To provide an electrical power system and an electrical power control device that make it possible to improve fuel efficiency compared to that conventionally possible. An electrical power system according to an embodiment includes fuel cells at a count of n, n representing an integer of 2 or greater, and a controller. The fuel cells are each configured to generate electrical power through electrochemical reactions. The controller is configured to set, based on a required output required in accordance with electrical power to be consumed by a load, an operation mode for each of the fuel cells to one mode determined from a plurality of modes including a first electrical power generation mode under which starting and stopping of generation of electrical power are repeated, a second electrical power generation mode under which generation of electrical power continues, and a stop mode under which generation of electrical power is stopped.