Fuel cell as a power supply system for an aircraft

Abstract

The invention relates to a power supply system (1) for supplying power to at least one propulsive or non-propulsive load of an aircraft (A), the power supply system (1) comprising: - at least one fuel cell (2) configured to be supplied with an air flow (FA) and with a hydrogen flow (FH) and - at least one control unit (8) designed to at least regulate an output voltage from the fuel cell (2) based on at least one parameter related to the air flow (FA) and / or to the hydrogen flow (FH). The invention also relates to an aircraft (A) comprising a power supply system (1).

Description

[0001] AIRCRAFT POWER SUPPLY SYSTEM

[0002] The present invention relates to the field of fuel cells.

[0003] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change. Technological research efforts have already led to very significant improvements in the environmental performance of aircraft.The Applicant takes into consideration the factors impacting all phases of design and development in order to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] To this end, the invention is the result of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing the environmental impact of aircraft.

[0006] BACKGROUND OF THE INVENTION

[0007] It has already been proposed to equip an aircraft with multiple electric propulsion motors to provide propulsion. Typically, the aircraft incorporates at least one fuel cell to electrically power these multiple electric propulsion motors. The fuel cell is a clean technology that generates power without emitting greenhouse gases. In practice, at least depending on the aircraft's flight phase, the power required by the electric propulsion motors varies, resulting in a variable electrical load for the fuel cell.

[0008] However, in practice, it is complex to obtain fuel cells that exactly meet the needs.

[0009] Thus, oversized fuel cells are generally used, which penalizes the mass and size.

[0010] SUBJECT OF THE INVENTION

[0011] The invention is intended, in particular, to improve a fuel cell power system for an aircraft.

[0012] SUMMARY OF THE INVENTION

[0013] For this purpose, the invention provides an electrical power supply system for at least one propulsive or non-propulsive load of an aircraft, the electrical power supply system comprising:

[0014] - at least one fuel cell configured to be powered by an air stream and a hydrogen stream, and

[0015] - at least one control unit arranged to regulate at least one output voltage of the fuel cell from at least one parameter related to the airflow and / or hydrogen flow.

[0016] The inventors realized that controlling the output voltage was particularly advantageous.

[0017] Indeed, in this way, the invention may not need to be associated with a device dedicated to stabilizing the output voltage of the invention (such as an electrical converter) to allow the proper operation of loads powered by the invention, a device which would be arranged downstream of the invention, at the level of the electrical loads, and which would therefore greatly complicate the supply of the loads.

[0018] Furthermore, controlling the output voltage can limit electrical losses in loads powered by the invention, particularly in the event of an increase in the current supplied by the battery and / or in the event of a high intensity of said current.

[0019] Furthermore, regulating the output voltage can counteract and / or slow down the aging of the fuel cell. This increases the cell's lifespan. This can be achieved by maintaining a constant output voltage over time, for a given net power output. Thus, regulating the fuel cell's output voltage via the control unit offers a significant advantage in improving the power supply system.

[0020] Depending on optional features, used individually or in whole or in combination:

[0021] - the parameter is linked to the pressure of the air flow and / or the pressure of the hydrogen flow and / or the stoichiometry of a hydrogen / oxygen mixture present in the fuel cell;

[0022] - at least one valve is arranged to regulate the airflow pressure and at least one sensor is arranged to measure the airflow pressure, the control unit being arranged to control the valve, from at least one signal transmitted by the sensor, in order to regulate the output voltage of the fuel cell;

[0023] - at least one valve is arranged to regulate the hydrogen flow pressure and at least one sensor is arranged to measure the hydrogen flow pressure, the control unit being arranged to control the valve arranged to regulate the hydrogen flow pressure, from at least one signal transmitted by the sensor arranged to measure the hydrogen flow pressure, in order to regulate the output voltage of the fuel cell;

[0024] - a compressor is arranged upstream of the fuel cell so that the airflow passes through the compressor before reaching the fuel cell and in which the control unit is arranged to control said compressor in order to regulate the output voltage of the fuel cell;

[0025] - the control unit is arranged to modify a compressor operating mode in order to regulate the output voltage of the fuel cell;

[0026] - the control unit is configured to maintain the output voltage within a given range, the range being bounded by a minimum output voltage and a maximum output voltage;

[0027] - the control unit defines the minimum output voltage via the air flow pressure and / or the hydrogen flow pressure;

[0028] - the control unit defines the maximum output voltage via the stoichiometry of a hydrogen / oxygen mixture present in the fuel cell.

[0029] The invention also relates to an aircraft comprising an electrical power supply system.

[0030] Other features and advantages of the invention will become apparent from the following description of particular and non-limiting embodiments of the invention.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Reference will be made to the attached drawings, including:

[0033] [Fig. 1] Figure 1 is a schematic representation of an aircraft comprising electric propulsion motors powered by electrical power systems, including at least one electrical power system according to a particular embodiment of the invention;

[0034] [Fig. 2] Figure 2 is a schematic representation of the power supply system according to a particular embodiment of the invention visible in Figure 1, the air circuits FA, hydrogen FH and cooling FR being represented in a very simplified manner;

[0035] [Fig. 3] Figure 3 is a schematic representation of the air supply circuit of the electrical supply system illustrated in Figure 2;

[0036] [Fig. 4] Figure 4 is a schematic representation of the hydrogen supply circuit of the electrical power supply system illustrated in Figure 2;

[0037] [Fig. 5] Figure 5 is a graph representing a polarization curve related to the power supply system illustrated in Figure 2 for two different inlet pressure values ​​of the air flow and / or hydrogen flow;

[0038] [Fig. 6] Figure 6 is a graph representing a polarization curve related to the power supply system illustrated in Figure 2 for two different stoichiometry values ​​of a hydrogen / oxygen mixture.

[0039] DETAILED DESCRIPTION OF THE INVENTION

[0040] With reference to Figure 1, an aircraft A is shown comprising at least one, and preferably several, electric propulsion motors M for its propulsion. Aircraft A further comprises at least one, and preferably at least two, electrical power supply systems 1 according to a particular embodiment of the invention. At least one of the electrical power supply systems 1 powers, for example, a propulsive or non-propulsive load of aircraft A. At least one, and preferably both, of the electrical power supply systems 1 each power at least one propulsive load and, preferably, several electric propulsion motors M. It is understood that the invention applies to any type of vehicle and, in particular, to any type of aircraft, whether single-engine, twin-engine, or multi-engine. The invention relates to airplanes, helicopters, and vertical takeoff and landing (VTOL) aircraft.

[0041] In this example, the electric propulsion motors M are positioned in the immediate vicinity of the electrical power supply system 1 to which they are associated in order to limit electrical losses.

[0042] In this example, the electrical power systems 1 are positioned under the lateral wings of aircraft A, but it goes without saying that their positioning could be different.

[0043] With reference to Figure 2, one of the power supply systems 1 will now be described. Here, the two power supply systems 1 are identical, so the following description also applies to the other power supply system.

[0044] The power supply system 1 is, here, mounted in an enclosure, also referred to as a "nacelle", extending along a longitudinal axis X.

[0045] In this example, the power supply system 1 includes a single fuel cell 2 electrically powering an electrical distribution box 3 configured to be directly connected to the propulsion electric motors M which here form the loads powered by the fuel cell 2.

[0046] As is known, fuel cell 2 generates electrical energy from an electrochemical reaction. Typically, different fluids circulate through fuel cell 2 to react and generate electrical energy. In this case, the reaction is a redox reaction between oxygen and hydrogen. Fuel cell 2 is thus supplied with oxygen and hydrogen. The redox reaction also produces water, which is discharged from fuel cell 2.

[0047] In this example, the power supply system 1 includes an air supply circuit 4 to provide an air flow FA including dioxygen to the fuel cell 2 and a hydrogen supply circuit 5 to provide a hydrogen flow FH to the fuel cell 2.

[0048] The fuel cell 2 is also supplied with coolant FR to remove the heat generated by the electrochemical reaction. Such coolant FR is a heat transfer fluid, such as oil or water, which may be mixed with additives. In this example, the power supply system 1 includes at least one cooling circuit 6.

[0049] The power supply system 1 also includes at least one collector 7 which is supplied by the air flow FA and the hydrogen flow FH to power cells 15 of the fuel cell 2 which are connected to the collector 7. The cells 15 themselves supply electrical energy to the electrical distribution box 3. The electrical energy at the input of the electrical distribution box 3 (and / or at the output of the fuel cell 2) is thus defined by an output voltage and an output current.

[0050] The power supply system 1 also includes a control unit 8. For example, the control unit 8 is arranged in the power distribution box 3. The control unit 8 is arranged to at least regulate an output voltage of the fuel cell 2 from at least one parameter related to the air flow FA (i.e. the inlet flow of the fuel cell 2 preferentially supplying the cathodes) and / or the hydrogen flow FH (i.e. the inlet flow of the fuel cell 2 preferentially supplying the anodes).

[0051] According to a first variant, the control unit 8 is arranged to at least regulate an output voltage of the fuel cell 2 from at least one parameter related to the airflow FA.

[0052] Figure 3 schematically represents the air supply circuit 16 of the fuel cell 2. Hereafter, the terms "upstream" and "downstream" should be understood according to the direction of air flow in the circuit.

[0053] The circuit comprises a first line 20 between the air intake line and the fuel cell inlet. This first line 20 includes, successively, a compressor 11, a heat exchanger 28, a humidifier 29, a distributor 30, and a valve 31. The first line 20 is also equipped with at least one first temperature sensor 32 arranged between the valve 31 and the distributor 30, and a second temperature sensor 33 arranged between the compressor 11 and the heat exchanger 28. The first line 20 also includes at least one humidity sensor 34 arranged between the humidifier 29 and the distributor 30. Finally, the first line 20 also includes at least one first pressure sensor 35 arranged between the compressor 11 and the heat exchanger 28.

[0054] The circuit also includes a second line 21 between the fuel cell outlet and a first air exhaust line 25. The second line 21 includes successively a valve 36 and the same humidifier 29 as the first line 20. The second line 21 also includes at least a second pressure sensor 37 arranged between the valve 36 and the humidifier 29.

[0055] The circuit also includes a third line 22 extending between the outlet of the heat exchanger 28 and a second air exhaust line 23, said third line 22 thus including a bypass valve 38.

[0056] The circuit also includes a fourth line 24 extending between the outlet of the distributor 30 and the second air exhaust line 23.

[0057] The second air exhaust line 23 includes a non-return valve 39 arranged downstream of the connection of the third line 22 and the fourth line 24 to the second air exhaust line 23. The non-return valve 39 is arranged to ensure a one-way flow of air from the distributor to the outside of the air supply circuit 16.

[0058] In operation, air enters the compressor 11 to be compressed and is then possibly cooled by the heat exchanger 28 (according for example to the data provided by the first temperature sensor 32 and / or the second temperature sensor 33) and possibly dried or humidified by the humidifier 29 (according for example to the data provided by the humidity measurement sensor 34) in order to reach the fuel cell.

[0059] It is therefore understood that the third line 22 makes it possible to secure the circuit by allowing air to be evacuated through the third line if the pressure in the circuit (according for example to the data provided by the first pressure sensor 35 and / or the second pressure sensor 37) exceeds a certain threshold.

[0060] Preferably at least one and preferably all elements of the circuit are controlled by control unit 8.

[0061] According to a first alternative, the control unit 8 is arranged to at least regulate the output voltage of the fuel cell 2 based on the airflow pressure FA (i.e., the airflow pressure FA at the fuel cell inlet). The parameter related to the airflow FA is therefore said pressure.

[0062] Preferably, the air supply circuit 16 includes at least one valve 9 and / or at least one pressure sensor 10 to regulate the airflow pressure FA. This valve 9 and / or pressure sensor 10 are, for example, in addition to the valves and pressure sensor already described. This valve 9 and / or pressure sensor 10 are thus exclusively dedicated to regulating the airflow pressure FA. This valve 9 and / or pressure sensor 10 are controlled by the control unit 8.

[0063] For example, pressure sensor 10 is a third pressure sensor 10. This third pressure sensor 10 is arranged here at the inlet of fuel cell 2. This allows for optimal measurement of the pressure at the cathodes. The third pressure sensor 10 is thus arranged on the first line 20.

[0064] For example, valve 9 is a proportional control valve, and for example, a proportional back-pressure control valve. Valve 9 is located here at the outlet of fuel cell 2. More precisely, valve 9 is located here on the first air exhaust line 25. Valve 9 is, for example, located downstream of humidifier 29.

[0065] In operation, the control unit 8 transmits (preferably continuously) a signal to the valve 9 based on at least one indication provided (preferably continuously) by at least one pressure sensor 10, so that the valve can modify its outlet flow rate if necessary. The valve 9 thus allows the pressure of the exhaust air to be regulated (and consequently, the pressure present at the fuel cell inlet). Alternatively, the control unit 8 is configured to regulate at least the output voltage of the fuel cell 2 based on the stoichiometry of the hydrogen / oxygen mixture at the fuel cell inlet. The parameter related to the airflow FA is therefore this stoichiometry of the hydrogen / oxygen mixture.

[0066] This second alternative can replace the first alternative or can be implemented at the same time as it, the control unit 8 acting on both the pressure of the air flow and on the stoichiometry of the hydrogen / oxygen mixture to regulate the output voltage.

[0067] To this end, the control unit 8 relies on elements already present in the air supply circuit 16. For example, the control unit 8 will control the compressor 11 to regulate the stoichiometry of the hydrogen / oxygen mixture. For example, the control unit 8 will control the compressor 11 to regulate the stoichiometry of the hydrogen / oxygen mixture by controlling the inlet mass flow rate of the compressor 11. For example, the control unit 8 will rely on at least one data point directly provided by the compressor 11 (operating point of the system, compression ratio, etc.) and / or on at least one data point provided by at least one sensor (for example, the first temperature sensor 32 and / or the second temperature sensor 33) to control the compressor 11 and thus regulate its inlet mass flow rate.

[0068] In operation, the control unit 8 controls (preferably continuously) the compressor 11 by controlling its mass flow rate. To this end, the control unit 8 transmits (preferably continuously) a signal to the compressor 11 based on at least one indication provided (preferably continuously) by at least one of the temperature sensors, at least one indication provided (preferably continuously) on the compression ratio of the compressor 11, and at least one indication provided (preferably continuously) on the operating point of the compressor 11. The compressor 11 thus allows the adjustment of the mass flow rate of the intake air (and consequently the stoichiometry of the hydrogen / oxygen mixture present at the inlet of the fuel cell).

[0069] According to a second variant, the control unit 8 is arranged to regulate at least one output voltage of the fuel cell 2 from at least one parameter related to the hydrogen flow FH. This second variant can replace the first variant or can be implemented at the same time as it, the control unit 8 controlling both at least one parameter related to the air flow (e.g. the air flow pressure and / or the stoichiometry of the hydrogen / oxygen mixture) and both a parameter related to the hydrogen flow to regulate the output voltage.

[0070] Figure 4 schematically represents the hydrogen supply circuit 17 of the fuel cell 2. Hereafter, the terms "upstream" and "downstream" should be understood according to the direction of flow of hydrogen in the circuit.

[0071] Said circuit 17 preferably includes a recirculation path 46 so that the hydrogen at the outlet of the fuel cell can be reinjected at the inlet of the fuel cell.

[0072] The circuit thus comprises a hydrogen inlet line 26, successively including a first valve 40 and downstream of it a first distributor 41 and downstream of it a second valve 42, the inlet line 26 supplying hydrogen to the anodes of the fuel cell. The circuit also comprises a hydrogen outlet line 27 extending from the fuel cell and successively including a third valve 43, a second distributor 44, and a purge valve 45. The recirculation path 46 extends between the second distributor 44 and the first distributor 41 and may optionally include one or more recirculation devices 14, such as one or more filters.Nominally the purge valve 45 is closed and the hydrogen at the outlet of the fuel cell flows from said cell through the second distributor 44, the recirculation path 46 and the first distributor 41 to be injected back into the fuel cell.

[0073] Preferably at least one and preferably all elements of the circuit are controlled by control unit 8.

[0074] Optionally, the control unit 8 is arranged to at least regulate the output voltage of the fuel cell 2 based on the hydrogen flow pressure FH (i.e., the hydrogen flow pressure FH at the fuel cell inlet). The parameter related to the hydrogen flow FH is therefore said pressure.

[0075] Preferably, the hydrogen supply circuit 17 includes at least one valve 12 and / or at least one pressure sensor 13 to regulate the pressure of the hydrogen flow FH. This valve 12 and / or this pressure sensor 13 are, for example, additional to the circuit elements already described. This valve 12 and / or this pressure sensor 13 are thus exclusively dedicated to regulating the pressure of the hydrogen flow FH. This valve 12 and / or this pressure sensor 13 are controlled by the control unit 8.

[0076] For example, the pressure sensor 13 is arranged upstream of the fuel cell 2. The pressure sensor 13 is thus arranged on the intake line 26. The pressure sensor 13 is, for example, arranged upstream of the first distributor 41 and / or downstream of the first valve 40.

[0077] For example, valve 12 is a proportional control valve. Valve 12 is located here at the fuel cell inlet. More precisely, valve 12 is located on the intake line 26. Valve 12 is, for example, located upstream of the first distributor 41 and / or downstream of the first valve 40. Valve 12 is, for example, located between the pressure sensor 13 and the first valve 40.

[0078] In operation, the control unit 8 transmits (preferably continuously) a signal to the valve 12 based on at least one indication provided (preferably continuously) by at least one pressure sensor 13, so that the valve can modify its output flow rate if necessary. The valve 12 thus allows the hydrogen pressure at the fuel cell inlet to be regulated.

[0079] Thus, regardless of the variant or alternative considered, the control unit 8 regulates the output voltage by acting on one or more parameters related to the airflow and / or the hydrogen flow. In this case, the control unit only acts on the following parameters to regulate the output voltage (and on no other physical parameter related to either flow, such as the flow temperature, and / or on any other physical parameter related to the power supply system, such as the fuel cell temperature – electrical consumption not being considered a physical parameter): airflow pressure (FA) and / or hydrogen flow pressure (FH) and / or stoichiometry of a hydrogen / oxygen mixture present in the fuel cell.

[0080] In particular, the control unit 8 constantly measures or estimates the output voltage to be controlled, then defines the setpoint(s) to modify one or more of the aforementioned influencing parameters, and transmits these setpoints to the relevant elements of the air supply circuit 16 or hydrogen supply circuit 17. The power supply system 1 described above allows control of the fuel cell output voltage in order to broaden the fuel cell's operating range and / or the use of the power supply system without complicating the electrical distribution box 3. Various applications are thus possible based on this principle, depending on how the output voltage is to be controlled.

[0081] As more clearly seen in Figures 5 and 6, the output voltage of the fuel cell 2 is a direct function of the power drawn by the propulsion motors M, as shown by a bias curve. This curve is defined on the x-axis by the current density supplied by cell 15 (i.e., the current supplied divided by the active area of ​​cell 15) and on the y-axis by the voltage supplied by a given cell 15 of the fuel cell. At any given instant, the relationship between the output voltage and the output current of said cell (and therefore indirectly of the fuel cell 2, since the output voltage of the fuel cell is simply the sum of the output voltages of its various cells) is given by its bias curve. Variations in the power drawn by the propulsion motors M, downstream of the fuel cell 2, thus cause movement along the bias curve.Since the power supplied by the cell (and therefore indirectly by the fuel cell 2) is the product of the current and the voltage, this means, due to the shape of the bias curve, that the higher the power supplied, the lower the output voltage of the cell (and therefore indirectly of the fuel cell 2). Preferably, the output voltage of the power supply system 1 should be maintained within a given range bounded by a minimum output voltage and a maximum output voltage.

[0082] Therefore, the control unit 8 is configured to maintain (preferably continuously) the output voltage between its minimum output voltage and its maximum output voltage despite variations in power called by the propulsion motors M.

[0083] Therefore, even in the case where several different stabilized power points are required by the propulsion motors M (for example according to different flight phases), the control unit 8 is configured to maintain the output voltage within the limits set by the interval.

[0084] To this end, as described for the first variant and the second alternative, the control unit 8 can maintain the output voltage within the aforementioned range by relying on one or more parameters corresponding to physical properties of the air flow FA and / or the hydrogen flow FH.

[0085] Indeed, and as can be seen in Figure 5, playing with the pressure of one and / or the other of the air flow FA and the hydrogen flow FH allows the polarization curve to be modified and therefore the output voltage to be affected.

[0086] Indeed, and as can be seen in Figure 6, playing with the stoichiometry of the hydrogen / oxygen mixture allows us to modify the polarization curve and therefore to play with the output voltage.

[0087] Preferably, the control unit 8 can maintain the output voltage above the minimum output voltage by adjusting a first parameter (e.g., the air flow pressure (FA) and / or the hydrogen flow pressure (FH)) and the control unit 8 can maintain the output voltage below the maximum output voltage by adjusting a second parameter different from the first parameter (e.g., the stoichiometry of the hydrogen / oxygen mixture present in the fuel cell 2). This facilitates the control of the power supply system 1.

[0088] Preferably, the control unit 8 takes into account, in order to regulate the output voltage, the electrical consumption of at least one of the elements of the power supply system and for example of at least one of the elements of the air circulation circuit 16 or of hydrogen 17 and for example of at least one element supplied at least in part by the power supply system itself.

[0089] For example, if compressor 11 is powered at least partially by fuel cell 2, compressor 11 may consume more electrical power when the control unit calls upon it to modify, for example, the stoichiometry of the hydrogen / oxygen mixture. Therefore, this increased power consumption of compressor 11 must be taken into account when regulating the output voltage.

[0090] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0091] In particular, although the parameters chosen here are related to the pressure of the air flow (FA) and / or the hydrogen flow (FH) and / or the stoichiometry of the hydrogen / oxygen mixture present in the fuel cell, other parameters could be regulated to control the fuel cell output voltage, such as the temperature of at least one fuel cell and / or the temperature of the air flow (FA) and / or the temperature of the air flow (FH) and / or the relative humidity of the air flow (FA) and / or the relative humidity of the hydrogen flow (FH). For example, regulating the temperature of the fuel cell allows for modification of the bias curve and therefore the output voltage. Similarly, regulating the temperature of the air flow (FA) and / or the hydrogen flow (FH) allows for modification of the bias curve and therefore the output voltage.For example, regulating the relative humidity of the air flow FA and / or the hydrogen flow FH allows the polarization curve and therefore the output voltage to be modified.

[0092] Furthermore, to ensure the stability of the output voltage, it may be possible to consider optimizing the stacking of cells, the number of stacks in series and / or the number of stacks in parallel.

[0093] Although the power supply system is mounted in the nacelle here, it could be installed in another part of the aircraft, for example, in the fuselage. Similarly, while the fuel cell shown here comprises cells connected to a collector, it can be configured differently. The fuel cell may not have a collector and / or may have a different number of cells than shown, for example, a single cell.

[0094] Although here the control unit 8 is arranged within the electrical distribution box 3, the control unit 8 could be arranged outside the electrical distribution box 3 and be arranged within another component of the electrical power system, or form a dedicated, isolated enclosure within the electrical power system. Although here the electrical power system supplies a propulsion load, it could also be used to supply a non-propulsive load. For example, the electrical power system could be arranged to provide power to an aircraft cabin (lighting, oven, air conditioning system, etc.). For example, the electrical power system could be arranged to provide power to the aircraft's navigation lights or the aircraft's wing de-icing system.

[0095] The invention is applicable to any aircraft power supply system whose output voltage is dependent on the power demanded by one or more loads, propulsive or non-propulsive, supplied by the power supply system.

[0096] The invention is applicable to any variable environment (variable pressure, change of altitude, aircraft cabin, etc.).

[0097] The invention is applicable to any electrochemical energy source with the supply of reagents carried on board an aircraft.

[0098] Although the intended application here is to maintain the output voltage within a given voltage range, either as a complement or replacement, the intended application may be different. For example, one could:

[0099] - temporarily increase the output voltage (to reduce the output current), for example in the case of stabilized operation at a transient and / or intermediate operating point of the propulsion motors M; and / or

[0100] - gradually increase the output voltage to compensate for the aging of the fuel cell in order to maintain a constant output voltage over time, for a given net power.

Claims

DEMANDS 1. Electrical power supply system (1) for at least one propulsive or non-propulsive payload of an aircraft (A), the electrical power supply system (1) comprising: - at least one fuel cell (2) configured to be powered by an air stream (FA) and by a hydrogen stream (EH) and - at least one control unit (8) arranged to regulate at least one output voltage of the fuel cell (2) from at least one parameter related to the air flow (FA) and / or the hydrogen flow (FH), the at least one parameter related to the air flow (FA) being able to be measured by: - at least one sensor (10) arranged to measure airflow pressure (AF) and / or - at least one sensor (32, 33) arranged to measure a temperature of an air supply circuit (16); and / or at least one parameter related to the hydrogen flow (FH) that can be measured by a sensor (13) arranged to measure a hydrogen flow (FH) pressure.

2. System (1) according to claim 1, wherein the parameter is related to the air flow pressure (FA), measured by the sensor (10) arranged to measure the air flow pressure, and / or to the hydrogen flow pressure (FH), measured by the sensor (13) arranged to measure a hydrogen flow pressure (FH), and / or to the stoichiometry of a hydrogen / oxygen mixture present in the fuel cell (2), measured by at least the sensor (32, 33) arranged to measure the temperature of the air supply circuit (16).

3. System (1) according to claim 1 or claim 2, comprising at least one valve (9) arranged to regulate the airflow pressure (FA) and at least the sensor (10) arranged to measure the airflow pressure, the control unit (8) being arranged to control the valve (9), from at least one signal transmitted by the sensor (10), in order to regulate the output voltage of the fuel cell (2).

4. System (1) according to any one of the preceding claims, comprising at least one valve (12) arranged to regulate the hydrogen flow pressure (FH) and at least one sensor (13) arranged to measure the hydrogen flow pressure (FH), the control unit (8) being arranged to control the valve (12) arranged to regulate the hydrogen flow pressure (FH), from at least one signal transmitted by the sensor (13) arranged to measure the hydrogen flow pressure, in order to regulate the output voltage of the fuel cell (2).

5. System (1) according to any one of the preceding claims, comprising a compressor (11) arranged upstream of the fuel cell (2) such that the airflow passes through the compressor (11) before reaching the fuel cell (2) and wherein the control unit (8) is arranged to control said compressor (11) in order to regulate the output voltage of the fuel cell (2).

6. System (1) according to claim 5, wherein the control unit (8) is arranged to modify an operating mode of the compressor (11) in order to regulate the output voltage of the fuel cell (2).

7. System (1) according to any one of the preceding claims, wherein the control unit (8) is configured to maintain the output voltage within a given range, the range being bounded by a voltage minimum output and maximum output voltage.

8. System (1) according to claim 7, wherein the control unit (8) sets the minimum output voltage via the air flow pressure (FA) and / or the hydrogen flow pressure (FH).

9. System (1) according to any one of claims 7 or 8, wherein the control unit (8) sets the maximum output voltage through the stoichiometry of a hydrogen / oxygen mixture present in the fuel cell (2).

10. Aircraft (A) comprising a system (1) according to any one of the preceding claims.

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