Fuel cell system, operating method for a fuel cell system and vehicle

Abstract

The invention relates to a fuel cell system (100) for converting energy, wherein the fuel cell system (100) comprises: - a first fuel cell stack (101), - a first anode subsystem (103), - a second fuel cell stack (105), - a second anode subsystem (107), - a single anode recirculation blower (109), - a computing unit (111), wherein the anode recirculation blower (109) is configured to recirculate a fluid in the first anode subsystem (103), wherein the computing unit (111) is configured to provide the power only through the first fuel cell stack (101) if the power to be provided by the fuel cell system (100) is less than a predetermined threshold, and to provide the power only through the first fuel cell stack (101) if the power to be provided by the fuel cell system (100) is greater than or equal to the predetermined threshold.to provide the power jointly by the first fuel cell stack (101) and the second fuel cell stack (105).

Description

[0001] The presented invention relates to a fuel cell system for converting energy, an operating method for operating the presented fuel cell system, a vehicle with the presented fuel cell system and a program product for carrying out the presented operating method, according to the appended claims. State of the art

[0002] A fuel cell system is a device for converting chemical energy contained in hydrogen and oxygen into electrical energy.

[0003] In this process, gaseous hydrogen is used as fuel via a polymer electrolyte membrane and reacted with oxygen from the air to produce pure water. Electricity and heat are produced as further reaction products in the cell.

[0004] Unlike combustion engines, no toxic exhaust gases are emitted and, provided the hydrogen is not produced from fossil fuels, no carbon dioxide is emitted either.

[0005] A fuel cell system consists of at least one fuel cell stack and several subsystems, such as an anode subsystem for supplying fuel, a cathode subsystem for supplying air and a cooling system for controlling the temperature of the fuel cell system.

[0006] Various system topologies are known, such as an arrangement with only one fuel cell stack or an arrangement with several fuel cell stacks. Disclosure of the invention

[0007] Within the scope of the invention presented, a fuel cell system, an operating method, a vehicle, and a program product are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the fuel cell system according to the invention naturally also apply in connection with the operating method according to the invention, the vehicle according to the invention, and the program product according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0008] The invention presented serves in particular to provide a possibility for a compact fuel cell system.

[0009] Thus, according to a first aspect of the invention presented, a fuel cell system for converting energy is presented.

[0010] The presented fuel cell system comprises a first fuel cell stack, a first anode subsystem, a second fuel cell stack, a second anode subsystem, a single anode recirculation blower and a computing unit, wherein the anode recirculation blower is configured to recirculate a fluid in the first anode subsystem and wherein the computing unit is configured to provide the power only through the first fuel cell stack if the power to be provided by the fuel cell system is less than a predetermined threshold value and to provide the power jointly through the first fuel cell stack and the second fuel cell stack if the power to be provided by the fuel cell system is greater than or equal to the predetermined threshold value.

[0011] In the context of the invention presented, a computing unit is understood to mean a computer, a processor, a control unit or any other programmable circuit.

[0012] The presented fuel cell system is based on the principle of using a first active anode subsystem and a second passive anode subsystem. This means that the first anode subsystem comprises an active anode recirculation fan that can be controlled to circulate, in particular recirculate, fluid in the first anode subsystem, so that the first fuel cell stack can be operated particularly fuel-efficiently even at low loads.

[0013] By combining the first fuel cell stack and the first anode subsystem with the second fuel cell stack and the second anode subsystem, the anode recirculation fan can be dimensioned particularly small, since it only has to circulate fluid in the first anode subsystem. Nevertheless, the presented fuel cell system is capable of handling high loads and providing high power thanks to the second fuel cell stack.

[0014] To switch between operation with only the first fuel cell stack and operation with the first fuel cell stack and the second fuel cell stack, the proposed fuel cell system includes a computing unit that compares a load to be provided, which is specified, for example, by a user via a user interface, with the specified threshold value. Accordingly, the second fuel cell stack is dynamically activated as needed if the power to be provided exceeds the threshold value.

[0015] The invention presented is of course not limited to only a first fuel cell stack and a second fuel cell stack, but can in particular comprise a plurality of second fuel cell stacks but also a plurality of first fuel cell stacks or a plurality of second anode subsystems and / or first anode subsystems.

[0016] The anode recirculation fan may be provided with an operating voltage of 12 volts or 24 volts.

[0017] Since the anode recirculation fan of the presented fuel cell system is designed or configured for a single anode subsystem to supply only one fuel cell stack, it can be designed to be particularly compact and performance-optimized. For this purpose, a recirculation fan with a low voltage of, for example, 12 volts or 24 volts can be selected, allowing the recirculation fan to be powered, for example, by a vehicle's electrical system.

[0018] Accordingly, it may be provided that the second anode subsystem is a passive anode subsystem that does not include an anode recirculation fan.

[0019] An anode subsystem without an anode recirculation fan may, for example, include a jet pump to provide a mixture that is fed to a corresponding fuel cell stack.

[0020] Due to the passive design without an anode recirculation fan, the second fuel cell stack is less fuel efficient than the first fuel cell stack, especially at partial load, so that the second fuel cell stack is only activated when high load requirements are encountered.

[0021] For example, the second fuel cell stack can be operated at full load and the first fuel cell stack can be operated in a modulating manner to adjust the power provided or to be provided.

[0022] It can further be provided that the fuel cell system comprises a first partial fuel cell system and a second partial fuel cell system, wherein the first partial fuel cell system comprises the first fuel cell stack, the first anode subsystem and first auxiliary units for operation independent of the second partial fuel cell system, and wherein the second partial fuel cell system comprises the second fuel cell stack, the second anode subsystem and second auxiliary units for operation independent of the first partial fuel cell system.

[0023] The presented fuel cell system can be designed as a so-called “twinbox” system, which comprises two independent fuel cell systems, or as a so-called “twinstack” system, which comprises two fuel cell stacks that share at least some auxiliary units.

[0024] Accordingly, it can further be provided that the first partial fuel cell system is an active fuel cell system and the second partial fuel cell system is a passive fuel cell system.

[0025] It may further be provided that the anode recirculation blower is configured only to supply the first fuel cell stack.

[0026] An anode recirculation blower configured only to supply the first fuel cell stack can be designed to be particularly compact, i.e., space-optimized and consumption-optimized.

[0027] According to a second aspect, the presented invention relates to an operating method for operating a fuel cell system comprising a first fuel cell stack and a second fuel cell stack, wherein the first fuel cell stack is supplied with fuel by a first anode subsystem comprising an anode recirculation blower and the second fuel cell stack is supplied with fuel by a second anode subsystem which does not comprise an anode recirculation blower.

[0028] The presented operating method comprises determining a power to be provided, comparing the power to be provided with a predetermined threshold value, operating only the first fuel cell stack to provide the power to be provided in the event that the power to be provided is less than the threshold value, and operating the first fuel cell stack and the second fuel cell stack jointly to provide the power to be provided in the event that the power to be provided is greater than or equal to the threshold value.

[0029] The presented operating procedure is used in particular for operating the presented fuel cell system.

[0030] Accordingly, it can be provided that a possible embodiment of the presented fuel cell system is selected as the fuel cell system.

[0031] According to a third aspect, the presented invention relates to a vehicle, wherein the vehicle comprises a possible embodiment of the presented fuel cell system.

[0032] The vehicle presented can, for example, be supplied with energy solely by the first fuel cell stack in a first operating mode and, in a second operating mode, be supplied with energy jointly by the first fuel cell stack and the second fuel cell stack. In particular, the first operating mode can be used for urban operation, which involves frequent load changes, thus protecting the second fuel cell stack from operation with changing loads and, as a result, being particularly durable.

[0033] Due to the particularly compact fuel cell system presented, the vehicle can also be designed to be particularly compact. For example, the vehicle presented could be a passenger car.

[0034] According to a fourth aspect, the presented invention relates to a program product, wherein the program product comprises program code means configured, when the program product is executed on a computing unit, to configure the computing unit to execute a possible embodiment of the presented operating method.

[0035] Advantages that are described in detail for the fuel cell system for converting energy according to the first aspect of the invention apply equally to the vehicle according to the second or third or fourth aspect of the presented invention.

[0036] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0037] They show schematically: Fig. 1 a representation of a first possible design of the presented fuel cell system, Fig. 2 a possible design of the proposed operating procedure, and Fig. 3 a possible design of the presented vehicle.

[0038] The figures are described in conjunction below. Like reference numerals indicate like features.

[0039] In Fig. 1 illustrates a fuel cell system 100 for converting energy. The fuel cell system 100 includes a first fuel cell stack 101, a first anode subsystem 103, a second fuel cell stack 105, a second anode subsystem 107, a single anode recirculation fan 109, and a processing unit 111.

[0040] The anode recirculation blower 109 is configured to recirculate a fluid in the first anode subsystem 109.

[0041] The computing unit 111 is configured to provide the power only through the first fuel cell stack 101 in the event that a power to be provided by the fuel cell system 100 is less than a predetermined threshold value, i.e. to activate only the first fuel cell stack 101, and to provide the power jointly through the first fuel cell stack 101 and the second fuel cell stack 105 in the event that the power to be provided by the fuel cell system 100 is greater than or equal to the predetermined threshold value, i.e. to operate the first fuel cell stack 101 and the second fuel cell stack 105 in parallel or simultaneously.

[0042] In Fig. 2 shows an operating method 200 for operating the fuel cell system 100.

[0043] The operating method 200 comprises a determination step 201 in which a power to be provided by the fuel cell system 100 is determined, an adjustment step 203 in which the power to be provided is adjusted to a predetermined threshold value, a first operating step 205 in which only the first fuel cell stack is activated to provide the power to be provided in the event that the power to be provided is less than the threshold value, and a second operating step 207 in which the first fuel cell stack and the second fuel cell stack are operated jointly or in parallel to provide the power to be provided in the event that the power to be provided is greater than or equal to the threshold value.

[0044] In Fig. 3 shows a vehicle 300. The vehicle 300 includes the fuel cell system 100 according to Fig. 1.

Claims

[1] Fuel cell system (100) for converting energy, wherein the fuel cell system (100) comprises: - a first fuel cell stack (101), - a first anode subsystem (103), - a second fuel cell stack (105), - a second anode subsystem (107), - a single anode recirculation fan (109), - a computing unit (111), wherein the anode recirculation blower (109) is configured to recirculate a fluid in the first anode subsystem (103), wherein the computing unit (111) is configured to provide the power only through the first fuel cell stack (101) in the event that a power to be provided by the fuel cell system (100) is less than a predetermined threshold value, and to provide the power jointly through the first fuel cell stack (101) and the second fuel cell stack (105) in the event that the power to be provided by the fuel cell system (100) is greater than or equal to the predetermined threshold value. [2] Fuel cell system (100) according to claim 1, characterized by that the anode recirculation fan (109) has an operating voltage of 12 volts or 24 volts. [3] Fuel cell system (100) according to claim 1 or 2, characterized by that the second anode subsystem (107) is a passive anode subsystem that does not include an anode recirculation fan. [4] Fuel cell system (100) according to one of the preceding claims, characterized by , that the fuel cell system (100) comprises a first partial fuel cell system and a second partial fuel cell system, wherein the first partial fuel cell system comprises the first fuel cell stack (101), the first anode subsystem (103) and first auxiliary units for operation independent of the second partial fuel cell system, and wherein the second partial fuel cell system comprises the second fuel cell stack (105), the second anode subsystem (107) and second auxiliary units for operation independent of the first partial fuel cell system. [5] Fuel cell system (100) according to claim 4, characterized by that the first partial fuel cell system is an active fuel cell system and the second partial fuel cell system is a passive fuel cell system. [6] Fuel cell system (100) according to one of the preceding claims, characterized by that the anode recirculation blower (109) is configured only to supply the first fuel cell stack (101). [7] An operating method (200) for operating a fuel cell system (100) comprising a first fuel cell stack (101) and a second fuel cell stack (105), wherein the first fuel cell stack (101) is supplied with fuel by a first anode subsystem (103) comprising an anode recirculation blower (109) and the second fuel cell stack (105) is supplied with fuel by a second anode subsystem (107) not comprising an anode recirculation blower, the operating method (200) comprising: - Determining (201) a service to be provided, - comparing (203) the power to be provided with a predetermined threshold value, - operating (205) only the first fuel cell stack (101) to provide the power to be provided in the event that the power to be provided is less than the threshold value, - operating (207) the first fuel cell stack (101) and the second fuel cell stack (105) together to provide the power to be provided in the event that the power to be provided is greater than or equal to the threshold value. [8] Operating method (200) according to claim 7, characterized by that a fuel cell system (100) according to one of claims 1 to 6 is selected as the fuel cell system (100). [9] Vehicle (300), wherein the vehicle (300) comprises a fuel cell system (100) according to one of claims 1 to 6. [10] A program product, wherein the program product comprises program code means configured, when the program product is executed on a computing unit, to configure the computing unit to execute an operating method (200) according to one of claims 7 or 8.

Images