Control device for a drive system having a fuel cell system

Abstract

The invention relates to a control device for a drive system, which drive system comprises: a fuel cell system having at least one fuel cell; and a mechanical power generator, wherein the control device forwards a received power command differently to the mechanical power generator depending on a received operating state variable of the fuel cell system.

Description

[0001] CONTROL DEVICE FOR A DRIVE SYSTEM WITH A FUEL CELL SYSTEM

[0002] DESCRIPTION

[0003] Technical area

[0004] The present invention relates to a control device for a drive system with a fuel cell system.

[0005] State of the art

[0006] The control device, or the fuel cell or propulsion system with a corresponding control device, can be used in particular in an aircraft, for example as an aircraft propulsion system. Such a propulsion system can comprise at least one fuel cell in addition to a mechanical power generator, e.g., an electric motor. This can generate the electrical power, which is then fed to the mechanical power generator and thus converted into propulsion. A corresponding power request, referred to herein as a power command or pilot command, can be received from the cockpit, for example, as a result of a human-initiated control signal or due to a partially or fully autonomous control system ("autopilot").

[0007] Description of the invention

[0008] The present invention is based on the technical problem of providing an advantageous control device for a drive system with a fuel cell system and a mechanical power generator.

[0009] This is achieved with the control device according to claim 1, which, in addition to a power command input for receiving the power command, has a power limiting device. This is arranged upstream of the mechanical power generator, i.e., is provided interposed between the power command input and the mechanical power generator. The power limiting device is configured to i) receive an operating state variable of the fuel cell system, and ii) forward the power command received via the power command input to the mechanical power generator with a time delay and / or to a reduced extent depending on the received operating state variable; or forward it to the mechanical power generator without delay and to the same extent; or forward it to the mechanical power generator to a greater extent.

[0010] Depending on the operating state of the fuel cell system, the power requested with the power command (pilot command) is thus not converted instantly and / or completely into the corresponding power of the mechanical power generator, but rather with a certain time delay. This can be advantageous for the fuel cell system, for example, in that it can prevent degradation processes in the fuel cell itself and / or in its supply system (see below for details).

[0011] On the other hand, the (slightly) delayed transmission of the pilot command cannot, in any case, represent a significant limitation compared to a conventional propulsion system with an internal combustion engine, because, for example, a thrust command is also converted into thrust with a time delay due to the underlying combustion process. In summary, the present approach involves querying the power retrieved from the fuel cell system by the mechanical power generator, depending on the operating state of the fuel cell system, not directly, but sometimes with a slight delay. This limitation in the power request is implemented in favor of overall more stable and sustainable operation.

[0012] In other operating states of the fuel cell system, however, the power command (pilot command), i.e., the requested power, can also be transmitted without delay and in full (second bullet point under ii.), i.e., without a time delay and to the requested extent. The operating state of the fuel cell system can be decisive for this, i.e., whether it can accommodate a corresponding power change without risk of degradation processes, etc.

[0013] Finally, another possibility is that the power command is transmitted to the mechanical power generator even more extensively (third bullet point under ii.), at least temporarily. In this case, the control system causes the mechanical power generator to request a higher power level than requested via the pilot command. This can be the case, for example, with an abrupt / severe thrust reduction, which the mechanical power generator then implements not instantly, but rather, for example, with a certain delay.

[0014] Preferred embodiments can be found in the dependent claims and the entire disclosure, whereby the presentation of the features does not always distinguish in detail between device and method or use aspects; in any case, the disclosure is implicitly to be read with regard to all claim categories. Furthermore, the presentation always relates to both the control device and a fuel cell system with such a control device, as well as a drive system with such a fuel cell system.

[0015] In summary, the subject matter relates to the control device itself, but additionally also to a fuel cell system having a corresponding control device and at least one fuel cell; and furthermore to a drive system having a corresponding fuel cell system and a mechanical power generator, in particular an electric motor.

[0016] Generally, "a" and "an" are to be read as indefinite articles in the context of the present disclosure and thus, unless expressly stated otherwise, always as "at least one" or "at least one." For example, the fuel cell system will comprise multiple or a plurality of fuel cells, which are assembled, for example, in the form of a fuel cell stack, also referred to as a stack (there may then be several such stacks in total). Nevertheless, for the sake of simplicity, reference will primarily be made below to "the fuel cell," which, however, can equally be read as referring to multiple fuel cells, in particular one or more fuel cell stacks.

[0017] The pilot or power command is received via the power command input and, without the present control device, would be passed directly to the mechanical power generator, i.e., its control unit. In this case, however, the power limiting device is interposed, where the received power command is compared with the operating state variable of the fuel cell system. As discussed in detail below, the "operating state variable" can comprise several individual values, i.e., one or more operating parameters of the fuel cell system. The power limiting device compares the requested power with the operating state variable, i.e., the operating parameter(s), and prioritizes one or the other.

[0018] In other words, the power limitation device represents a selection logic; the pilot or power command, for example, is transmitted directly or with a slight delay / reduction. In simple terms, this allows power generation and power demand to be well coordinated. The "delayed" transmission of the power command, which generally represents a delta to the actual state, can, for example, affect a few seconds, e.g., at least 1 s, 2 s, or 3 s (with possible upper limits of, for example, a maximum of 10 s or 8 s). After this time, the power command can be fully implemented. The "reduction" of the power command can, for example, mean a reduction of at least 10%, 30%, or 50%; initially, 0% is generally also possible.

[0019] According to a preferred embodiment, a limit value or limits are stored for the operating parameter(s). Depending on the parameter type, etc., multiple limit values ​​can be stored, for example; in particular, a lower and an upper limit value can be specified (min / max value). If the respective operating parameter lies within the limit, the power command can be transmitted directly; otherwise, it is delayed / reduced.

[0020] The limit value adjustment can take into account an actual state and / or a new state that would result from the actual state upon implementation of the power command. Regardless of these details, the limit value adjustment can be advantageous, for example, in that it allows for the implementation of a control architecture with comparatively low complexity that is simultaneously functional and robust. The limit value adjustment can be performed relatively quickly, for example, without complex calculations / algorithms.

[0021] In a preferred embodiment, several operating parameters are considered during control, for which several limit values ​​are stored, preferably an upper and a lower limit for each operating parameter (see above). Furthermore, a selection logic can be provided that prioritizes the operating parameters differently. The query "Limit value exceeded / undershot - yes / no" can therefore also be weighted according to the respective operating parameter, e.g., according to criticality (risk of damage if the limit is exceeded / undershot). Alternatively or additionally, the extent to which a respective limit is exceeded or undershot can also be taken into account.

[0022] According to a preferred embodiment, the power limiting device takes into account an operating parameter of the fuel cell, in particular a current output by the fuel cell and / or an applied voltage. The current and voltage, i.e., the power, can be used to determine an operating point of the fuel cell.

[0023] In a preferred embodiment, the control device has a speed detection device, i.e., a tachometer for measuring the speed generated by the mechanical power generator, in particular the electric motor. The speed can be taken into account in the selection logic in addition to the operating state variable of the fuel cell system. In a preferred embodiment, the power limitation device transmits the pilot or power command with a time delay and / or a reduced value depending on the received speed.

[0024] As mentioned at the beginning, the subject matter also relates to a fuel cell system comprising a fuel cell and a control device. The fuel cell system preferably comprises a fuel cell supply system, which can, for example, supply the actual fuel cell with a reaction gas(es) and / or provide cooling, such as pumping a cooling fluid through the fuel cell.

[0025] In a preferred embodiment, a component temperature, an available cooling capacity, a surge limit, and / or a reaction gas value are used as operating parameters of the fuel cell supply system. The component temperature relates to a component of the supply system, e.g., a pump or, in general, a supply motor. The reaction gas value can, for example, relate to a pressure and / or volume flow rate at which a respective reaction gas, e.g., hydrogen, oxygen, or air, can be made available to the fuel cell. The surge limit can characterize the operating range of a pump in the supply system, while the cooling capacity can characterize the operating range of a cooling system.

[0026] In a preferred embodiment, the fuel cell supply system has a supply system controller, which is preferably arranged in parallel with the power limiting device. The latter means that the power command is fed to the supply system controller in parallel with the power limiting device, i.e., for example, in the case of a delayed / reduced transmission to the mechanical power generator, the power command is already available to the supply system controller. The supply system controller can then preferably prepare the fuel cell supply system for the power command, for example, in the case of an increased power demand, already start up the cooling system and / or adjust a pump output, etc. In simple terms, the interim period of the delay can therefore already be used for the adjustment, meaning that the power command can be implemented more quickly overall.

[0027] As mentioned at the beginning, the application also relates to a propulsion system that, in addition to the fuel cell system, has at least one mechanical power generator supplied with electrical power by the fuel cell system. Furthermore, the propulsion system can also have, for example, a propulsor associated with the mechanical power generator for generating thrust, such as a propeller.

[0028] The application further relates to a method for operating such a drive system or fuel cell system or the control device, wherein the power limiting device i) receives an operating state variable of the fuel cell system, and ii) transmits a power command received via the power command input to the mechanical power generator with a time delay and / or to a reduced extent depending on the received operating state variable; or transmits it to the mechanical power generator without delay and to the same extent; or transmits it to the mechanical power generator to a greater extent. Brief description of the drawings

[0029] In the following, the invention is explained in more detail using an exemplary embodiment, whereby the individual features within the scope of the independent claims can also be essential to the invention in other combinations and no distinction is made in detail between the different claim categories.

[0030] In detail,

[0031] Figure 1 shows a drive system comprising a fuel cell system with a control device, in a schematic diagram;

[0032] Figure 2 some process steps in a flow chart

[0033] Figure 3 shows a schematic representation of an aircraft with a propulsion system according to Figure 1.

[0034] Preferred embodiment of the invention

[0035] Fig. 1 shows a schematic representation of a drive system 100, which has a fuel cell system 10 and a mechanical power generator 110, in the present example an electric motor 111 for driving a propeller 120. The fuel cell system 10 has at least one fuel cell 20, in detail this can be one or more fuel cell stacks (not shown in detail).

[0036] A fuel cell supply system 30 supplies the fuel cell 20 with, among other things, reaction gases 31, for example, hydrogen and air. For this purpose, the fuel cell supply system 30 is equipped with appropriate hardware 35, e.g., pumps, lines, etc. Furthermore, it has a supply system controller 36, which controls the hardware 35 of the fuel cell supply system 30.

[0037] The fuel cell system 10 further comprises a control device 1, which initially has a power command input 2 and a power limiting device 3. A power command 90, for example a command to increase thrust, is received via the power command input 2, which is shown separately here for illustration purposes but can also be implemented as an integrated interface, for example. The power command 90 is not forwarded directly to the mechanical power generator 110 or its control unit 105; instead, the power limiting device 3 is interposed.

[0038] In addition to the power command 90, the power limiting device 3 receives an operating state variable 50 of the fuel cell system 10, specifically several operating parameters 51, 52. With or in the intermediate power limiting device 3, the power command 90 is compared with the operating state variable 50 and, if necessary, passed on with some time delay and / or to a reduced extent.

[0039] Furthermore, as can be seen from Figure 1, the power command 90 is also fed to the supply system controller 36 in parallel with the adjustment in the power limitation detection device 3, which can accordingly already initiate the corresponding adaptation of the fuel cell supply system 10 to the power command 90.

[0040] The control device 1 further comprises a speed detection device 125, with which the speed 53 generated by the mechanical power generator 110 can be detected. The speed 53 is also fed into the power limiting device 3 and can therefore, for example, lead to a delayed or reduced transmission of the power command 90 if a predefined limit is exceeded or undershot. Furthermore, a power value 54 is also fed to the power limiting device 3, with which the power command 90 can be determined as the actual state as a delta to the target state.

[0041] In Fig. 2, some method steps are schematically summarized in a flow chart. After receiving 201 the power command 90 and receiving 202 the operating state variable 50, the power command is forwarded 205 depending on the operating state variable 50, possibly with some time offset and / or to a reduced extent. The operating parameters 51 of the fuel cell can be, in particular, a current I and / or a voltage U, while the operating parameter(s) 52 of the fuel cell supply system can be, for example, a temperature T or a power P of the cooling system or a pump parameter. The power limiting device can also take into account the rotational speed 53; see above for details.

[0042] Fig. 3 shows a schematic representation of an aircraft 200, which has the propulsion system 100 with the fuel cell 20 and the control device, which is not further referenced in detail in Fig. 3. The mechanical power generator 110 is an electric motor 111, which drives a propeller 120.

[0043] LIST OF REFERENCE SYMBOLS

[0044] Control device 1

[0045] Power command input 2

[0046] Power limitation device 3

[0047] Fuel cell system 10

[0048] Fuel cell 20

[0049] Fuel cell supply system 30

[0050] Reaction gases 31

[0051] Hardware 35

[0052] Supply system control 36

[0053] Operating state variable 50

[0054] Operating parameters 51, 52

[0055] Speed ​​53

[0056] Performance value 54

[0057] Power command 90

[0058] Drive system 100

[0059] Control unit 105 mechanical power generator 110

[0060] Electric motor 111

[0061] Propeller 120

[0062] Speed ​​detection device 125

[0063] Aircraft 200

[0064] Receive (Power Command) 201

[0065] Receive (operating state variable) 202

[0066] Reception (RPM) 203

[0067] Transfer 205

Claims

CLAIMS 1. A control device (1) for a drive system (100) comprising a fuel cell system (10) with at least one fuel cell (20) and a mechanical power generator (110), wherein the control device (1) comprises: a power command input (2) for receiving (201) a power command (90), and a power limiting device (3) connected between the power command input (2) and the mechanical power generator (110), wherein the power limiting device (3) is configured to i) receive (202) an operating state variable (50) of the fuel cell system (10), and ii) forward (205) the power command (90) received via the power command input (2) to the mechanical power generator (110) with a time delay and / or at a reduced level depending on the received operating state variable (50); or - to be passed on to the mechanical power generator (110) without delay and to the same extent; or to be passed on to the mechanical power generator (110) to a greater extent.

2. Control device (1) according to claim 1, in which a limit value is stored for an operating parameter (51, 52) of the operating state variable (50), wherein the transmission of the power command (90) according to step ii) takes place as a function of a comparison with the limit value.

3. Control device (1) according to claim 2, in which limit values are stored for several operating parameters (51, 52), wherein a selection logic Operating parameters (51, 52) are prioritized differently with regard to their criticality.

4. Control device (1) according to one of the preceding claims, wherein the operating state variable (50) of the fuel cell system (10) to be received comprises an operating parameter (51) of the at least one fuel cell (20).

5. Control device (1) according to claim 4, wherein the operating parameter (51) of the at least one fuel cell (20) to be received comprises at least one of a voltage and a current.

6. Control device (1) according to one of the preceding claims, with a speed detection device (125) which is designed to detect a speed (53) generated by the mechanical power generator (110).

7. Control device (1) according to claim 6, wherein the power limiting device (3) is configured to receive a speed (53) from the speed detection device (125) and to transmit the power command (90) received via the power command input (2) to the mechanical power generator (110) with a time delay and / or to a reduced extent depending on the received speed (53).

8. Fuel cell system (10), with at least one fuel cell (20), and a control device (1) according to one of the preceding claims.

9. Fuel cell system (10) according to claim 8, which comprises a fuel cell supply system (30), wherein the operating state variable (50) of the Fuel cell system (10) comprises an operating parameter (52) of the fuel cell supply system (30).

10. The fuel cell system (10) of claim 9, wherein the operating parameter (52) of the fuel cell supply system (30) comprises at least one of a component temperature, an available cooling capacity, a surge limit, and a reaction gas value.

11. Fuel cell system (10) according to claim 9 or 10, wherein the fuel cell supply system (30) has a supply system controller (36), wherein the supply system controller (36) is configured to receive the power command (90) in parallel with the power limiting device (3).

12. Fuel cell system (10) according to claim 9 or 10, wherein the supply system controller (36) is configured to adapt the fuel cell supply system (30) to the power command (90), even if the power command (90) is initially transmitted to the mechanical power generator (110) with a delay and / or to a reduced extent.

13. Propulsion system (100), in particular of an aircraft (200), with a mechanical power generator (110), and a fuel cell system (10) according to one of claims 8 to 12.

14. A method for operating a drive system (100) according to claim 13 or a fuel cell system (10) according to one of claims 8 to 10 or a control device (1) according to one of claims 1 to 7, in which the power limiting device (3) receives i) an operating state variable (50) of the fuel cell system (10), and ii) a power command (90) received via the power command input (2) is forwarded (205) to the mechanical power generator (110) with a time delay and / or to a reduced extent depending on the received operating state variable (50); or is forwarded to the mechanical power generator (110) without delay and to the same extent; or is forwarded to the mechanical power generator (110) to a greater extent.

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