The present disclosure relates to a fuel cell system and a method of controlling a heater thereof. A fuel cell system according to the present disclosure includes a cathode oxygen depletion (COD) heater that is disposed on a line through which cooling water flowing into a fuel cell stack circulates and heats the cooling water or consumes residual power of the fuel cell stack, and a controller that determines power consumption according to a target heating amount of the COD heater and controls an operation of the COD heater based on the determined power consumption.

Disclosed herein is a method of controlling start/stop of a parallel fuel cell system, which, when controlling stop of a parallel fuel cell system in which two or more fuel cell systems are connected in parallel, considers operating state information of each fuel cell system, such as a current speed value of an air compressor and an opening degree of an air-exhaust-side air pressure valve of a fuel cell stack. Accordingly, the method can calculate a delay time for performing fuel cell system stop control for the two or more fuel cell systems, and sequentially perform the fuel cell system stop control for the two or more fuel cell systems based on the calculated delay time. Therefore, it is possible to minimize output delay of each fuel cell system and to achieve deterioration prevention and efficiency improvement of the fuel cell stack by fuel cell system start/stop control.

Disclosed herein is a method of controlling start/stop of a parallel fuel cell system, which, when controlling stop of a parallel fuel cell system in which two or more fuel cell systems are connected in parallel, considers operating state information of each fuel cell system, such as a current speed value of an air compressor and an opening degree of an air-exhaust-side air pressure valve of a fuel cell stack. Accordingly, the method can calculate a delay time for performing fuel cell system stop control for the two or more fuel cell systems, and sequentially perform the fuel cell system stop control for the two or more fuel cell systems based on the calculated delay time. Therefore, it is possible to minimize output delay of each fuel cell system and to achieve deterioration prevention and efficiency improvement of the fuel cell stack by fuel cell system start/stop control.

The invention relates to a shut-off valve (1) for temporarily interrupting the supply of air to a fuel cell stack in a fuel cell system, said shut-off valve comprising a valve piston (3) which can move back and forth in a cylindrical housing bore (2) and is prestressed in the direction of a sealing seat (5) by the spring force of a spring (4), wherein a connection between an air inlet duct (6) and an air outlet duct (7) is established or interrupted depending on the axial position of the valve piston (3). According to the invention, inside the housing bore (2), one end of the valve piston (3) delimits a spring chamber (8) which accommodates the spring (4) and is subjected to ambient pressure, and the other end thereof delimits a control chamber (9) which can be connected to the air inlet duct (7) via a control valve (10). The invention also relates to a fuel cell system comprising a shut-off valve (1) according to the invention.

The invention relates to a shut-off valve (1) for temporarily interrupting the supply of air to a fuel cell stack in a fuel cell system, said shut-off valve comprising a valve piston (3) which can move back and forth in a cylindrical housing bore (2) and is prestressed in the direction of a sealing seat (5) by the spring force of a spring (4), wherein a connection between an air inlet duct (6) and an air outlet duct (7) is established or interrupted depending on the axial position of the valve piston (3). According to the invention, inside the housing bore (2), one end of the valve piston (3) delimits a spring chamber (8) which accommodates the spring (4) and is subjected to ambient pressure, and the other end thereof delimits a control chamber (9) which can be connected to the air inlet duct (7) via a control valve (10). The invention also relates to a fuel cell system comprising a shut-off valve (1) according to the invention.

A method of controlling a fuel cell device includes: a step of purging a hydrogen supply unit of a fuel electrode and purging a gas supply unit of an oxidant electrode when an operation of the fuel cell device ends; a step of measuring a voltage between the fuel electrode and the oxidant electrode and determining whether the voltage is greater than a predetermined threshold; a step of continuing power generation in the fuel cell device when the voltage is greater than the predetermined threshold; and a step of depressurizing the hydrogen supply unit and the gas supply unit when the voltage is equal to or less than the predetermined threshold.

Disclosed are a method of improving fuel efficiency of a fuel cell electric vehicle, and an apparatus and a system therefor. The method includes collecting navigation information and vehicle speed information, calculating a coasting line when a specified event point is detected based on the navigation information, determining whether deceleration is necessary by comparing a current traveling speed with a coasting line speed corresponding to a current location, and changing a criterion for determining whether to enter a fuel cell stop (FC STOP) state when the deceleration is necessary as a determination result.

Disclosed are a method of improving fuel efficiency of a fuel cell electric vehicle, and an apparatus and a system therefor. The method includes collecting navigation information and vehicle speed information, calculating a coasting line when a specified event point is detected based on the navigation information, determining whether deceleration is necessary by comparing a current traveling speed with a coasting line speed corresponding to a current location, and changing a criterion for determining whether to enter a fuel cell stop (FC STOP) state when the deceleration is necessary as a determination result.

A fuel cell system includes a plurality of fuel cell units each including a fuel cell, a fuel cell cooling system having a heat exchanger that exchanges heat between a primary-side coolant, and a secondary-side coolant flowing through the fuel cell, and a coolant pump that adjusts the flow rate of the secondary-side coolant, and a controller that controls the fuel cell, a cooling device, and a cooling system that supplies the primary-side coolant from the cooling device to each fuel cell unit. During stop of operation of the fuel cell system, the cooling device supplies the primary-side coolant having a temperature equal to or higher than a predetermined temperature to each fuel cell unit, and the controller activates the coolant pump to cause the secondary-side coolant to flow through the heat exchanger, in one or more fuel cell units in which the fuel cell has a possibility of freezing.

An apparatus and a method for controlling a fuel cell system includes a fuel cell system including a fuel cell stack, a balance of plant for operating the fuel cell stack, and a fuel cell controller configured for controlling the BOP, a first power converter located between the fuel cell stack and a first voltage battery and including a bidirectional low voltage DC/DC converter, a second power located between the fuel cell stack and a second voltage battery to include a single bidirectional DC/DC converter module, and a controller configured for operating the first power converter or the single bidirectional DC/DC converter module of the second power converter, when the fuel cell system is started or stopped, and controlling the first power converter or the second power converter to supply driving power to the BOP using electrical energy of the first voltage battery or the second voltage battery.