Electric energy supply system for a mobile platform and vehicle having an electric energy supply system

Abstract

The invention relates to an electrical energy supply system for a mobile platform and to a vehicle having an electrical energy supply system. The electrical energy supply system (10) comprises an electrical assembly (12) having at least two fuel cell units (14), which are arranged in the electrical assembly (12) in a manner connected in series (16) to one another and are embodied for providing a voltage supplied to at least one electrical consumer (18). The electrical energy supply system (10) further comprises a ground unit (20) assigned a reference potential, and at least two control units (22) respectively assigned to at least one of the fuel cell units (14), wherein each of the at least two control units (22) is embodied for detecting a voltage of the assigned fuel cell unit (14) relative to the reference potential.

Description

Technical Field

[0001] This invention relates to a fuel cell-based power supply system. More particularly, it relates to a power supply system for a mobile platform and an air vehicle having such a power supply system. Background Technology

[0002] Fuel cell systems are becoming increasingly important, especially in drive systems for mobile platforms. Such fuel cell systems, such as PEM (proton exchange membrane) fuel cells, have voltage levels as individual modules up to approximately 400 V. Furthermore, this is production-dependent and depends on the number of individual cells typically integrated into a fuel cell module. The number of individual cells limits the module's voltage. PEM fuel cells, which can be presented as a so-called single stack, typically provide approximately 30 kW to 50 kW of electrical power. These fuel cells can be combined by connecting them in parallel to achieve higher power outputs. Here, the voltage level refers to the voltage level of a single stack. In automotive applications, if a higher voltage level is required, a DC / DC converter that subsequently provides a higher operating voltage is used. The purpose of requiring a higher operating voltage is to keep the current load, as well as the overall size and weight of the electric drive motor, as low as possible for a given input power. Summary of the Invention

[0003] The purpose of this invention is to provide an improved fuel cell-based power supply system.

[0004] This objective is achieved by the subject matter described below. Exemplary implementations are derived from the following description.

[0005] According to one aspect of the invention, an electrical power supply system for a mobile platform, such as a vehicle, is provided. The electrical power supply system includes an electrical assembly having at least two fuel cell units arranged in series with each other, and configured to provide voltage to at least one power-consuming device. The electrical power supply system also includes a grounding unit assigned a reference potential, and at least two control units correspondingly assigned to at least one of the fuel cell units, wherein each of the at least two control units is configured to detect the voltage of the assigned fuel cell unit relative to the reference potential.

[0006] The energy supply system according to the invention can be used on mobile platforms or in mobile applications. Such mobile platforms are, for example, vehicles, such as land vehicles, air vehicles, and water vehicles.

[0007] The power supply system according to the invention provides the possibility of arranging individual fuel cell units, or so-called fuel cell stacks, in series, with particular consideration for requirements in the aerospace field, thereby increasing the voltage. Since the aerospace field requires significantly higher drive power compared to the automotive field, increasing the system voltage is crucial. The current generated by the system and the weight of the piping can be kept at relatively low levels using the power supply system described herein.

[0008] Furthermore, examples of the present invention provide the possibility of maintaining the voltage at as low a level as possible relative to a reference potential, thereby taking into account the higher operating altitudes of the aircraft and therefore the pressure-related breakdown voltage. Similarly, an electrical supply system can ensure emergency operation in case of failure and provide simple combined operation with additional energy storage. The electrical supply system can achieve the elimination of the need for additional electronic components, i.e., DC / DC converters, to provide voltage.

[0009] As previously mentioned, the power supply system has an electrical assembly with at least two fuel cell units. The fuel cell unit, also referred to herein as a fuel cell stack or fuel cell pile, can correspondingly include one or more fuel cells, such as PEM (proton exchange membrane) fuel cells. Here, the at least two fuel cell units are arranged in series in the electrical assembly, i.e., arranged in series within the power supply system. In other words, the at least two fuel cell units are connected in series. Any number of fuel cell units can be connected in series.

[0010] The fuel cell unit provides voltage to at least one power-consuming device. This device can be a drive unit of a mobile platform, particularly one or more drive motors or electric motors. The drive motors can obtain their AC voltage power, for example, via an inverter that converts the DC voltage of the fuel cell unit into an adjustable and, depending on the configuration, variable AC voltage with a selectable and, depending on the implementation, variable output frequency. The adjustable voltage and variable frequency can be used to control the speed of the electric drive motors. The inverter can also operate during generator operation to recover braking energy generated in the electric motor and subsequently supply it to a traction battery housed in the electrical components.

[0011] The grounding unit is provided for the power supply system, and the grounding unit is equipped with a reference potential. For example, the grounding unit can be a major conductive structural element of a mobile platform, which is equipped with a zero potential serving as a reference potential for electrical components.

[0012] As previously described, the power supply system has at least two control units, which are correspondingly assigned to at least one fuel cell unit in the fuel cell unit. A first control unit may, for example, be assigned to or electrically coupled and / or communicatively coupled to a first fuel cell unit in the at least two fuel cell units, while a second control unit may be assigned to or electrically coupled and / or communicatively coupled to a second fuel cell unit in the at least two fuel cell units. Alternatively, one or more of the at least two control units may be correspondingly assigned to or electrically coupled and / or communicatively coupled to multiple fuel cell units.

[0013] Each of the at least two control units is configured to detect the voltage of the assigned fuel cell unit relative to a reference potential, such as zero potential. Furthermore, each of the at least two control units can be configured to adjust the voltage of its associated fuel cell unit relative to the reference potential. Such adjustment can be performed in such a way that the total power generated by the fuel cell units is distributed as evenly as possible across the at least two fuel cell units. For example, this adjustment can be performed such that the fuel cell units output substantially the same amount of electrical power to electrical components and supply it to power-consuming devices.

[0014] Communication and control can be performed relative to a reference ground or reference potential. It is particularly advantageous to link the control and regulation of the fuel cell unit and any existing additional units (such as turbines, fan blades, pumps, etc.) to a reference potential to avoid other potential disconnections.

[0015] According to one embodiment, the power supply system does not include power electronic devices for increasing the voltage provided by the fuel cell unit, in particular a DC / DC converter, in addition to the fuel cell unit.

[0016] This could mean that, in the case of the aforementioned series connection of at least two fuel cell units for increasing voltage, the necessity for additional power electronics (e.g., DC / DC converters) is reduced to connecting additional energy storage devices, such as batteries, capacitors, or so-called supercapacitors. Especially to keep system weight low and achieve the highest possible reliability for a given power requirement, it is advantageous to omit power electronics for increasing system voltage (as is the case with parallel fuel cell connections) and to provide the most direct possible power flow.

[0017] According to one embodiment, the at least two control units are correspondingly configured to adjust the voltage of the assigned fuel cell unit relative to a reference potential. This adjustment can be performed in such a way that the electrical power supplied by the corresponding fuel cell unit is substantially the same.

[0018] Therefore, the control unit can, for example, adjust or control the voltage or voltage rise on the fuel cell unit associated with it, thereby regulating the voltage supplied to the power-consuming device by the assigned fuel cell unit individually and independently of the voltage supplied by another fuel cell unit. In a preferred embodiment, the control unit adjusts the voltage of the fuel cell unit associated with it so that the generated power is distributed to the fuel cell unit as evenly as possible.

[0019] According to one embodiment, the fuel cell units are arranged in a symmetrical circuit relative to the grounding unit, such that a first voltage difference between the first fuel cell unit and a reference potential and a second voltage difference between the second fuel cell unit and a reference potential are the same or substantially the same.

[0020] The reference potential used for the fuel cell unit is the grounding unit or ground. The fuel cell units are connected symmetrically with respect to the grounding unit. This type of connection minimizes the voltage relative to the grounding unit while ensuring a high system voltage.

[0021] In other words, the reference potential is connected at a location between the at least two fuel cell units in the electrical assembly. The term "symmetry" is understood here as "electrical symmetry." This relationship will be explained in more detail in the accompanying drawings. Such an electrically symmetrical circuit is advantageous because the voltage relative to the reference potential (ground) is minimized compared to other circuit types.

[0022] When the electrical assembly has, for example, four fuel cell units, every two fuel cell units can be arranged on either side of a reference potential, thereby positioning every two fuel cell units in an electrically symmetrical circuit relative to the reference potential. Here, the voltage difference between the two fuel cell units connected upstream of the reference potential and the voltage difference between the two fuel cell units connected downstream of the reference potential can be detected by the at least two control units. This detection can initiate adjustment of the voltage supplied to each fuel cell unit when a deviation occurs in the detected voltage difference.

[0023] According to one embodiment, in a symmetrical circuit, a reference potential is located on the positive voltage side of the first fuel cell unit and on the negative voltage side of the second fuel cell unit.

[0024] Therefore, the symmetrical circuit provides bipolar components relative to the reference potential, and differs from the configuration where the reference potential of the communication and control devices is located on the negative voltage side of all fuel cell units. In the aforementioned symmetrical circuit, this remains true for positive voltages, but not for negative voltages. For the latter, the reference potential of the communication and control devices is still related to the grounding unit, however, the connection terminals of the fuel cell power components are located on the positive side of the respective fuel cell unit. This will also be more clearly seen in the accompanying drawings.

[0025] According to one embodiment, the voltage on the negative voltage side of the electrical component is the same as the reference potential.

[0026] This is an alternative configuration for the aforementioned symmetrical circuit. Here, the reference potential for the active components and the housing is particularly relevant to the grounding unit. In this type of connection in a TN / TT power grid, the negative return line carrying current from the power-consuming equipment to the fuel cell unit is the same as the grounding unit.

[0027] In one implementation, all active components of the electrical assembly are decoupled from a reference potential.

[0028] This is an alternative configuration for the aforementioned symmetrical circuit. Again, the fuel cell units are connected in series; however, the reference potential is in the form of an IT power grid. Here, only the housing is associated with the grounding unit; the active components of the electrical assembly are separated from the housing, i.e., electrically decoupled.

[0029] According to one embodiment, the power supply system further includes an energy storage device or battery, which is arranged in parallel relative to the at least two fuel cell units.

[0030] The energy storage device can be a capacitor, such as a supercapacitor. Ensuring a unidirectional current flow direction allows for the parallel connection of such energy storage devices, as this prevents current from flowing into the fuel cell. Parallel connection of energy storage devices enables higher system power and higher peak power output, which might be impossible to achieve using only the fuel cell. Furthermore, energy storage also allows for the utilization of recovered energy (even at reduced speeds, the symmetrical adjustment power of the drive unit is still enhanced).

[0031] In applications involving air transportation, energy recovery can be achieved during descent, where the rotation of the blades / propellers can power an electrically driven machine in generator mode. Another example is the autorotation in helicopters or similar aircraft, which also enables energy recovery. To absorb recovered energy, electrical energy storage devices or other power-consuming devices, such as additional batteries, can be used.

[0032] By changing and adjusting the operating point or operating pressure of the fuel cell, its charging state and operating state (charging / discharging) can be controlled when the battery is used as an energy storage device. These controls can also be performed by one or more of the at least two control units.

[0033] According to one embodiment, the power supply system further includes a switching device or switch arranged in parallel relative to one of the at least two fuel cell units to provide current bypassing the fuel cell unit.

[0034] To provide redundancy or address emergency situations, it is advantageous to use the energy source as reliably as possible. For example, the at least two fuel cell units are designed with redundant auxiliary units, also known as BOPs (Balance of Plants), allowing the system to continue operating in the event of a failure (e.g., pump failure). To this end, the fuel cell units can be equipped with anti-parallel current paths, for example in the form of diodes, to ensure current flow even in the event of fuel cell unit failure. This ensures power extraction despite a drop in system voltage. Therefore, the power supply system can continue operating by using a switch connected in parallel with the failed fuel cell unit.

[0035] According to one aspect of the invention, an air vehicle having an electrical power supply system as described above and below is provided. The air vehicle may be an aircraft, particularly a transport aircraft, or other flying equipment such as a drone or helicopter. Attached Figure Description

[0036] Figure 1 An embodiment of an electrical power supply system is shown, which has a fuel cell unit in a circuit that is symmetrical with respect to a reference potential.

[0037] Figure 2 An electrical power supply system according to another embodiment is shown, which has a fuel cell unit in a circuit that is symmetrical with respect to a reference potential.

[0038] Figure 3An electrical power supply system according to an embodiment is shown, wherein the voltage on the negative voltage side of the fuel cell unit assembly is the same as the reference potential.

[0039] Figure 4 An electrical power supply system according to an embodiment is shown, wherein all active components of the electrical assembly having a fuel cell unit are decoupled from a reference potential.

[0040] Figure 5 An air vehicle having an electrical power supply system according to an embodiment is shown. Detailed Implementation

[0041] The illustrations in the figures are schematic and not to scale. If the same reference numerals are used in different figures in the following description of the figures, they refer to the same or similar elements. However, the same or similar elements may also be referred to by different reference numerals.

[0042] Figure 1 A power supply system 10 is shown. The power supply system 10 includes an electrical assembly 12 having two fuel cell units 14, namely a first fuel cell unit 14a and a second fuel cell unit 14b, which are arranged in series 16 and provide voltage for supplying power to a power-consuming device 18. The power supply system 10 also includes a grounding unit 20 assigned a reference potential, such as zero potential for the electrical assembly. The power supply system 10 also includes two control units 22, namely a first control unit 22a and a second control unit 22b, which are respectively assigned to at least one of the two fuel cell units 14a, 14b, wherein each of the two control units 22a, 22b is configured to detect the voltage of the assigned fuel cell unit 14a, 14b relative to the reference potential. Here, the first control unit 22a can be assigned to the first fuel cell unit 14a, and the voltage of the first fuel cell unit 14a can be detected or measured. Similarly, a second control unit 22b can be assigned to the second fuel cell unit 14b, and the voltage of the second fuel cell unit 14b can be detected or measured. The minimum voltage of the first fuel cell unit 14a is, for example, -400 V, and the maximum voltage of the first fuel cell unit 14a is, for example, -250 V. The minimum voltage of the second fuel cell unit 14b is, for example, +250 V, and the maximum voltage of the second fuel cell unit 14b is, for example, +400 V. These two control units 22a and 22b are coupled to the reference potential of the grounding unit, so the voltages of the fuel cell units 14a and 14b can be adjusted or controlled independently relative to the reference potential.

[0043] exist Figure 1In the example shown, fuel cell units 14a and 14b are arranged in a symmetrical circuit 24 relative to grounding unit 20. Therefore, the first control unit 22a can detect a first voltage difference between the first fuel cell unit 14a and a reference potential, and the second control unit 22b can detect a second voltage difference between the second fuel cell unit 14b and the reference potential. Thus, the voltages of the two fuel cell units 14a and 14b can be adjusted individually by these two assigned control units 22a and 22b. The adjustment of control units 22a and 22b can make the voltages of the two fuel cell units 14a and 14b substantially the same.

[0044] exist Figure 1 In the symmetrical circuit 24 shown, the reference potential is located on the positive voltage side 142a of the first fuel cell unit 14a and on the negative voltage side 141b of the second fuel cell unit 14b. Therefore, a bipolar assembly is proposed relative to the reference potential, in which the power components of the first fuel cell unit 14a are connected via the positive terminal (indicated by the symbol "+") of the first fuel cell unit 14a, and the power components of the second fuel cell unit 14b are connected via the negative terminal of the second fuel cell unit 14a. Here, precise joint operation management of the positive and negative fuel cell units 14a and 14b relative to the reference potential is performed to avoid different positive and negative voltages relative to the reference potential (ground). For this purpose, the voltage of each fuel cell unit 14a and 14b and its individual cells, as well as the voltage relative to the reference potential (ground), can be continuously monitored through the control and regulation of the control units 22a and 22b. Therefore, potential faults and connection failures or degradations relative to the reference potential can be detected earlier, and appropriate measures can be taken.

[0045] The power supply system 10 also includes line sections that electrically connect the components of the electrical assembly 12 described herein to each other and form a circuit in which power-consuming devices 18 are used. The power-consuming device 18 is, for example, an electric motor of a moving platform. Figure 1 In the electrical component 12 shown, current flows from the negative voltage side 141a of the first fuel cell unit 14a to the positive voltage side 142a of the first fuel cell unit 14a, and then from the negative voltage side 141b of the second fuel cell unit 14b to the positive voltage side 142b of the second fuel cell unit 14b.

[0046] The power supply system 10 also includes an energy storage device 26, which is connected in parallel with respect to the at least two fuel cell units 14 within the electrical assembly 12. The parallel connection of the energy storage device 26 enables higher system power and higher peak power outputs exceeding those available from the fuel cell units 14a and 14b. In the energy storage device 26, recovered energy can be absorbed by the power-consuming device 18 when it operates in generator mode, as recovered energy cannot be absorbed by the fuel cell units 14a and 14b.

[0047] The power supply and power ratio of the fuel cell units 14a, 14b and the energy storage device 26 can be set or adjusted via control units 22a and 22b. The charging state and operating state (charging / discharging) of the energy storage device 26 can be adjusted by changing the operating point of the fuel cell units 14a and 14b, such as the operating pressure.

[0048] The power supply system 10 also includes switching devices 28 arranged in parallel relative to one of the at least two fuel cell units 14a, 14b to bypass fuel cell units 14a, 14b in providing current. Specifically, a first switching device 28a, such as a diode, is connected in parallel with the first fuel cell unit 14a, and a second switching device 28b, such as another diode, is connected in parallel with the second fuel cell unit 14b. This parallel connection ensures that the failure of one or more fuel cell units 14a, 14b does not affect the operation of the entire power supply system 10, as current flow is still guaranteed.

[0049] Electrical component 12 may also include inverter 32, which converts the DC voltage supplied by fuel cell units 14a, 14b into AC voltage subsequently supplied to power-consuming device 18. Figure 1 As shown, an additional switching device 34 or an additional unit 30 can be provided in the electrical assembly 12.

[0050] Figure 2 An electrical power supply system 10 is shown, which has a fuel cell unit 14 in a circuit 24 that is symmetrical with respect to a reference potential. Here, Figure 2 All connection methods and characteristics of the electrical component 12 shown are the same as those of the electrical component 12 shown. Figure 1 The connection methods and characteristics of the electrical components shown are, in principle, the same, therefore this applies accordingly to Figure 1 The content described. However, in Figure 2The illustrated electrical assembly 12 also includes a redundancy scheme, comprising two redundant auxiliary units 30a and 30b, or so-called BoP (Balance of Plant) components, which, like the fuel cell units 14a and 14b, are also related to a reference potential, thus avoiding the cost of potential separation of such components. All housings of the electrical assembly 12 are related to a reference potential. Here, in the illustrated symmetrical circuit 24, the reference potential is located on the positive voltage side (indicated by the symbol "+") of the first fuel cell unit 14a and the negative voltage side of the second fuel cell unit 14b. The minimum voltage of the first fuel cell unit 14a is, for example, -400 V, and the maximum voltage of the first fuel cell unit 14a is, for example, -250 V. The minimum voltage of the second fuel cell unit 14b is, for example, +250 V, and the maximum voltage of the second fuel cell unit 14b is, for example, +400 V. The housing including the first control unit 22a may include the first auxiliary unit 30a, and the housing including the second control unit 22b may include the second auxiliary unit 30b, thus further avoiding potential separation between these components.

[0051] Figure 3 A power supply system 10 is shown, wherein the voltage on the negative voltage side 36 of the fuel cell unit 14 assembly is the same as the reference potential. The minimum voltage of the first fuel cell unit 14a is, for example, +250 V, and the maximum voltage of the first fuel cell unit 14a is, for example, +400 V. The minimum voltage of the second fuel cell unit 14b is, for example, +250 V, and the maximum voltage of the second fuel cell unit 14b is, for example, +400 V. As described above, the two fuel cell units 14a and 14b are connected in series, and the two fuel cell units 14a and 14b are respectively equipped with control units 22a and 22b for regulation; however, with… Figure 1 and Figure 2 The configuration shown differs; the reference potential is now set on the negative voltage side 36 of all fuel cell units 14. The grounding unit 20 is therefore coupled to the negative terminal of the first fuel cell unit 14a. The reference potential for the active components and housing of the electrical components is grounded. In this type of connection in a TN / TT power grid, the negative return line from the power-consuming device 18 to the first fuel cell 14a is either the same as grounded or coupled to the grounding unit 20. Figure 3 In the configuration shown, with Figure 1 and Figure 2 Compared to the configuration shown, a higher voltage can occur relative to the reference potential, which may require a larger insulation distance.

[0052] Figure 4A power supply system 10 is shown, in which all active components of electrical assembly 12 are decoupled from a reference potential. As described above, the two fuel cell units 14a and 14b are connected in series, and each fuel cell unit 14a and 14b is equipped with a control unit 22a and 22b for regulation; however, all active components of electrical assembly 12 are decoupled from the reference potential. Only the housing of each component is related to the reference potential. Here, the minimum voltage of the first fuel cell unit 14a is, for example, +250 V, and the maximum voltage of the first fuel cell unit 14a is, for example, +400 V. The minimum voltage of the second fuel cell unit 14b is, for example, +250 V, and the maximum voltage of the second fuel cell unit 14b is, for example, +400 V. Such a DC voltage connection in the form of an IT grid has advantages, so any potential asymmetry will not cause system failure. To ensure the symmetry of the voltages of fuel cell units 14a and 14b relative to the reference potential and thus keep the load on the insulation distance at a low level, the voltages of fuel cell units 14a and 14b are continuously monitored and the voltages of each fuel cell unit 14a and 14b are adjusted as necessary.

[0053] This invention provides a power supply system 10 having a series connection 16 of two or more fuel cell stacks 14a, 14b for increasing the voltage used to drive electric drive equipment. Here, it is particularly possible to provide voltages exceeding 800 V, where additional power electronics, such as DC / DC converters, can be eliminated, which also helps improve the reliability of the entire system. Also, to keep the system weight as low as possible for a given power demand, it is advantageous to eliminate power electronics, for example, that would be provided in parallel connection to increase the system voltage, and to provide the most direct possible power flow. Especially under high power demand, higher voltage is beneficial for keeping the current as low as possible. However, in the case of air transport, for example, where the mobile platform using the power supply system 10 according to the invention may have a potentially high operating altitude, it is difficult to significantly increase the system voltage, because the insulation distance is limited by such an altitude factor. In operation at low air pressure, due to the higher operating altitude, Paschen's law (the breakdown voltage related to air pressure) needs to be considered. Here, the power supply system 10 in… Figure 1 and Figure 2 The configuration shown is particularly advantageous because it is consistent with the configuration in [the text]. Figure 3 and Figure 4 Compared to other configurations shown, the former, based on the described bipolar assembly, minimizes the maximum voltage (to ground) relative to the reference potential. The housing of the components used is typically related to the reference potential, similar to protective grounding; therefore, higher voltages relative to the reference potential also require greater insulation distances, especially in… Figure 3 and 4 This might be the case in the configuration shown.

[0054] Figure 5 A mobile platform 100 in the form of an air vehicle 100 is shown, which includes the aforementioned power supply system 10.

[0055] Additionally, it should be noted that "comprising" does not exclude other elements or steps, and "an" or "a" does not exclude a plurality. Furthermore, it should be noted that features or steps already described with reference to one of the above embodiments, as well as combinations of other features or steps with other embodiments described above, may be used. Reference numerals in the claims should not be considered limiting.

Claims

1. A power supply system (10) for a mobile platform (100), comprising: An electrical assembly (12) having at least two fuel cell units (14) arranged in the electrical assembly (12) in series (16) with each other and configured to provide voltage to at least one power-consuming device (18); Grounding unit (20), wherein the grounding unit is equipped with a reference potential; as well as At least two control units (22) are assigned to at least one of the fuel cell units (14), wherein each of the at least two control units (22) is configured to detect the voltage of the assigned fuel cell unit (14) relative to the reference potential and to individually adjust the voltage of the assigned fuel cell unit (14) relative to the reference potential.

2. The power supply system (10) according to claim 1. The power supply system (10) therein does not include power electronics for increasing the voltage provided by the fuel cell unit (14), except for the fuel cell unit (14).

3. The power supply system (10) according to claim 1. The at least two control units (22) are respectively configured to individually adjust the voltage of the assigned fuel cell unit (14) relative to the reference potential, so that the electrical power provided by the fuel cell unit (14) is the same accordingly.

4. The power supply system (10) according to claim 1. The fuel cell unit (14) is arranged in a symmetrical circuit (24) relative to the grounding unit (20), such that the first voltage difference between the first fuel cell unit (14a) of the at least two fuel cell units (14) and the reference potential and the second voltage difference between the second fuel cell unit (14b) of the at least two fuel cell units (14) and the reference potential are the same.

5. The power supply system (10) according to claim 4. In the symmetrical circuit (24), the reference potential is located on the positive voltage side (142a) of the first fuel cell unit (14a) and on the negative voltage side (141b) of the second fuel cell unit (14b).

6. The power supply system (10) according to claim 1. The voltage on the negative voltage side of the electrical component (12) is the same as the reference potential.

7. The power supply system (10) according to claim 1. All active components of the electrical component (12) are decoupled from the reference potential.

8. The power supply system (10) according to claim 1 further comprises: An energy storage device (26) is provided in parallel relative to the at least two fuel cell units (14).

9. The power supply system (10) according to claim 1 further comprises: A switching device (28) is arranged in parallel relative to the fuel cell units (14a, 14b) of the at least two fuel cell units (14) to provide current around the fuel cell units (14a, 14b).

10. An air vehicle (100) having an electrical power supply system (10) according to any one of claims 1 to 9.

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