Abstract: A method for diagnosing the operating state of an electrochemical system in real-time comprising a stack of cells, said method comprising steps for performing voltage measurements of said cells. Said method further comprises: real-time processing of the voltage measurements (61) thus performed, in order to extract specific waveforms (40) therefrom, converting said specific waveforms in order to generate specific points (65) therefrom of the real-time operation of the electrochemical system, and comparing these specific points of the real-time operation and specific points (75) of an off-line operation of the electrochemical system that originate from a conversion of specific waveforms (74) extracted from voltage measurements (78) performed off-line, while the electrochemical system is placed in known operating states including fault states, so as to produce information (69) relating to the real-time operating state of the electrochemical system.

Abstract: A method for diagnosing the operating state of an electrochemical system in real-time comprising a stack of cells, said method comprising steps for performing voltage measurements of said cells. Said method further comprises: real-time processing of the voltage measurements (61) thus performed, in order to extract specific waveforms (40) therefrom, converting said specific waveforms in order to generate specific points (65) therefrom of the real-time operation of the electrochemical system, and comparing these specific points of the real-time operation and specific points (75) of an off-line operation of the electrochemical system that originate from a conversion of specific waveforms (74) extracted from voltage measurements (78) performed off-line, while the electrochemical system is placed in known operating states including fault states, so as to produce information (69) relating to the real-time operating state of the electrochemical system.

Abstract: The invention relates to a cooling system for a fuel cell (2), comprising a main heat-transfer-fluid circuit including a main circulation pump (6) and a heat exchanger (8) with the exterior, which feed an upstream pipe (12) supplying the fluid to the cells (4) of the fuel cell, said fluid leaving the cells via a downstream pipe (14) in order to return to the main pump. The system is characterised in that a secondary circuit, comprising a secondary circulation device (30) that circulates the fluid in an alternate manner, is connected in parallel with the main circuit to the upstream (12) and downstream (14) pipes and in that one or more controlled valves (10, 16) allow the main circuit and the secondary circuit to operate independently.

Abstract: The invention relates to a cooling system for a fuel cell, comprising a main heat-transfer-fluid circuit including a circulation pump (6) and a heat exchanger (8) with the exterior, which feed an upstream pipe (12) supplying the fluid to the cells (4) of the fuel cell, said fluid leaving the cells via a downstream pipe (14) in order to return to the main pump. The invention is characterized in that the main circuit comprises a three-port controlled valve (10, 16) on each upstream (12) and downstream (14) pipe, the third available port (10c) of the upstream pipe (12) being connected to the inlet of the pump (6) and the third available port (16c) of the downstream pipe (14) being connected to the outlet of the pump in order to establish a secondary fluid circuit.

Abstract: The invention relates to a cooling system for a fuel cell, comprising a main heat-transfer-fluid circuit including a circulation pump (6) and a heat exchanger (8) with the exterior, which feed an upstream pipe (12) supplying the fluid to the cells (4) of the fuel cell, said fluid leaving the cells via a downstream pipe (14) in order to return to the main pump. The invention is characterised in that the main circuit comprises a three-port controlled valve (10, 16) on each upstream (12) and downstream (14) pipe, the third available port (10c) of the upstream pipe (12) being connected to the inlet of the pump (6) and the third available port (16c) of the downstream pipe (14) being connected to the outlet of the pump in order to establish a secondary fluid circuit.

Abstract: The invention relates to a cooling system for a fuel cell (2), comprising a main heat-transfer-fluid circuit including a main circulation pump (6) and a heat exchanger (8) with the exterior, which feed an upstream pipe (12) supplying the fluid to the cells (4) of the fuel cell, said fluid leaving the cells via a downstream pipe (14) in order to return to the main pump. The system is characterised in that a secondary circuit, comprising a secondary circulation device (30) that circulates the fluid in an alternate manner, is connected in parallel with the main circuit to the upstream (12) and downstream (14) pipes and in that one or more controlled valves (10, 16) allow the main circuit and the secondary circuit to operate independently.

Abstract: The invention relates to a method for operating a fuel cell (2), which is to be implemented by means of a control computer (10) that drives the level of current generated by the cells of the fuel cell, said fuel cell including a means for tracking the temperature of the cells, said method being characterized in that it comprises the following steps: when starting the operation of the fuel cell, if the temperature of the cells is at a sufficiently low level, particularly less than 0° C., driving a series of cycles of current intervals including, alternately for each cycle, a low non-zero current (Imin), and then a current interval comprising raising and lowering the strength of the current at programmed speeds.

Abstract: The invention relates to a current collecting plate (50) for a fuel cell. According to the invention, the plate comprises a substantially constant thickness of an electrically conductive material along the stacking axis of the cells of the fuel cell, forming a plane at the end of the stack in order to collect the current from the fuel cell. The invention is characterised in that it comprises holes (52) pierced in the thickness of the material, extending parallel to the plane of the plate.

Abstract: A fuel-cell stack including a stack of fuel cells with intermediate conductive bipolar plates. The bipolar plates include internal flow channels for flow of a heat-transfer fluid. The channels are connected to a circuit of a cooling system. Only some of the bipolar plates include internal flow channels that are temporarily or permanently not in service.