Search

DE-102024210794-A1 - Load distribution of the air supply for a fuel cell across multiple compressors

DE102024210794A1DE 102024210794 A1DE102024210794 A1DE 102024210794A1DE-102024210794-A1

Abstract

Method (100) for operating an arrangement comprising at least one first compressor (1) and a second compressor (2) for supplying a gaseous operating medium (3) to at least one fuel cell (4) with a predetermined pressure or pressure ratio, wherein the first compressor (1) and the second compressor (2) are connected in series in the flow direction of the operating medium (3), comprising the steps: • a first compression (1a) to be performed by the first compressor (1) and a second compression (2a) to be performed by the second compressor (2) are specified (110) such that the operating equipment (3) has the required pressure or the required pressure ratio to its original pressure after both compressions have been carried out; • Operating parameters (1b, 2b) are determined for the first compressor (1) and for the second compressor (2) (120) such that both compressors (1, 2) deliver their specified compression ratio (1a, 2a) when operating with the respective operating parameters (1b, 2b); • Based on these operating parameters (1b, 2b), a rating number (5a) is determined using a predefined rating function (5) (130), which indicates the extent to which the operation of the compressors (1, 2) with the operating parameters (1b, 2b) is in accordance with at least one first predefined optimization objective; • at least the combination of the first compression to be performed (1a) and the second compression to be performed (2a) is optimized to the goal (140) that a re-evaluation with the evaluation function (5) leads to a better evaluation number (5a).

Inventors

  • Jochen Braun
  • Nicole Bayerle

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241111

Claims (17)

  1. Method (100) for operating an arrangement comprising at least one first compressor (1) and a second compressor (2) for supplying a gaseous operating medium (3) to at least one fuel cell (4) at least at a predetermined pressure or pressure ratio, wherein the first compressor (1) and the second compressor (2) are connected in series in the flow direction of the operating medium (3), comprising the steps of: • defining a first compression (1a) to be performed by the first compressor (1) and a second compression (2a) to be performed by the second compressor (2) (110) such that the operating medium (3) has at least the required pressure or the required pressure ratio to its original pressure after both compressions have been performed; • Operating parameters (1b, 2b) are determined for the first compressor (1) and for the second compressor (2) (120) such that both compressors (1, 2) deliver their specified compression ratio (1a, 2a) when operating with the respective operating parameters (1b, 2b); • Based on these operating parameters (1b, 2b), a rating number (5a) is determined using a predefined rating function (5) (130), which indicates the extent to which the operation of the compressors (1, 2) with the Operating parameters (1b, 2b) are consistent with at least one first predefined optimization goal; • at least the combination of the first compression to be performed (1a) and the second compression to be performed (2a) is optimized to the goal (140) that a re-evaluation with the evaluation function (5) leads to a better evaluation number (5a).
  2. Procedure (100) according to Claim 1 , wherein the first specified optimization goal includes a total energy consumption and/or electrical power of the air compression, and/or a total wear and/or dynamics of the arrangement of the first compressor (1) and the second compressor (2) (131).
  3. Procedure (100) according to one of the Claims 1 until 2 , wherein in addition a steepness (5b) of the dependence of the rating number (5a) on the first and/or second compaction to be performed (1a, 2a), and/or on at least one operating parameter (1b, 2b), with regard to the first optimization objective is determined (150).
  4. Procedure (100) according to one of the Claims 1 until 3 , wherein at least the combination of the first compression to be performed (1a) and the second compression to be performed (2a) is additionally optimized to at least one further optimization goal (141).
  5. Procedure (100) according to Claim 3 and 4 , wherein • using the gradient (5b) a range (1c, 2c) is determined (160) in which the first and/or second compression to be performed (1a, 2a), and/or the at least one operating parameter (1b, 2b), can be changed without leaving the optimum with respect to the first optimization objective; and • the first and/or second compression to be performed (1a, 2a), and/or the at least one operating parameter (1b, 2b), are optimized within this range (1c, 2c) with respect to the at least one further optimization objective (170).
  6. Procedure (100) according to one of the Claims 1 until 5 , wherein a shift in the optimal compression of the first and/or second compression to be performed with regard to the first optimization objective (1a*, 2a*), or of the optimal at least one operating parameter (1b*, 2b*) with regard to the first optimization objective, and/or a change in the slope (5b), is considered an indicator of aging or other degradation of the arrangement of the first and second compressors (1, 2) (180).
  7. Procedure (100) according to Claim 6 , wherein, in response to the detection of aging or other degradation, a probable cause of the aging or degradation and/or a probable location where the aging or degradation manifests itself is determined using at least one other measurement relating to the operating condition of the arrangement consisting of the first and second compressors (1, 2) (190).
  8. Procedure (100) according to one of the Claims 1 until 7 , where a gradient-based optimization method is chosen (142, 171).
  9. Procedure (100) according to one of the Claims 1 until 8 , wherein the optimization is carried out on a simulation model (143, 172) which models at least the arrangement of the first compressor (1) and the second compressor (2).
  10. Procedure (100) according to Claim 9 , wherein the simulation model additionally models the behavior of • at least one fuel cell (4) supplied by the arrangement, and/or • at least one vehicle in which the arrangement and the fuel cell (4) are carried (143a, 172a).
  11. Procedure (100) according to one of the Claims 1 until 10 , wherein during the optimization at least temporarily • a fuel cell (4) supplied by the arrangement of the first compressor (1) and the second compressor (2) is kept in a steady operating state (144, 173) and • changing power requirements on this fuel cell are balanced by drawing energy from an energy storage device (145, 174).
  12. Procedure (100) according to one of the Claims 1 until 11 , wherein • an optimal first compression (1a*) to be performed by the first compressor (1) and a second compression (2a*) to be performed by the second compressor (2), and/or • operating parameters (1b*, 2b*) of the first and second compressors (1, 2) with which the compressors (1, 2) each deliver such an optimal compression (1a*, 2a*), in association with one or more state variables (6) that characterize • the operating state of the arrangement consisting of the first compressor (1) and the second compressor (2), and/or • the operating state of at least one fuel cell (4) supplied by this arrangement, and/or • the operating state of a vehicle in which the arrangement and the at least one fuel cell (4) are carried, are stored in a database (7), and/or as training parameters. game is used for a machine learning model to be trained (8) (200).
  13. Method (300) for operating an arrangement of at least one first compressor (1) and a second compressor (2) for supplying a gaseous operating medium (3) to at least one fuel cell at a predetermined pressure or pressure ratio, wherein the first compressor (1) and the second compressor (2) are connected in series in the flow direction of the operating medium (3), comprising the steps of: • determining one or more state variables (6) (310) that characterize ◯ the operating state of the arrangement consisting of the first compressor (1) and the second compressor (2), and/or ◯ the operating state of at least one fuel cell (4) supplied by this arrangement, and/or ◯ the operating state of a vehicle in which the arrangement and the at least one fuel cell (4) are transported; • Based on these state variables (6), a first compression (1a) to be performed by the first compressor (1) and a second compression (2a) to be performed by the second compressor (2) are determined such that the operating equipment (3) has the required pressure or the required pressure ratio to its original pressure after both compressions have been carried out, and/or related operating parameters (1b, 2b) for the first and second compressors (1, 2) are retrieved from a database (7) and/or from a trained machine learning model (8) (320).
  14. Procedure (100, 300) according to one of the Claims 12 until 13 , where the altitude of a position where a vehicle with the arrangement of the first compressor and the second compressor is located is chosen as the state variable (6) (201, 311).
  15. Procedure (100, 300) according to one of the Claims 1 until 14 , wherein the arrangement consisting of the first compressor (1) and the second compressor (2) is operated with the compressions (1a, 2a) and/or operating parameters (1b, 2b) to be provided which were found in the course of optimization or retrieved from the database (7) and/or from the machine learning model (8) (210, 330).
  16. Computer program containing machine-readable instructions which, when executed on one or more computers, cause the computer(s) to perform the procedure (100) according to one of the Claims 1 until 15 to execute.
  17. Machine-readable data carrier and/or download product containing the computer program according to Claim 16 .

Description

The present invention relates to the supply of one or more fuel cells with air as an oxidizing agent, particularly on board vehicles where the requirements for the compression of this air are constantly changing. State of the art In a fuel cell, fuel is placed in an anode compartment and an oxidizer in a cathode compartment on either side of an ion-permeable electrolyte. Ions, such as hydrogen ions, from the fuel migrate through the electrolyte into the cathode compartment, while electrons released during the ionization of the fuel reach the cathode compartment via an external electrical load. There, the ions, electrons, and oxygen from the oxidizer react to form, for example, water as a byproduct. Ambient air, which is available in any quantity and does not need to be stored in a tank, is used as the oxidizing agent, particularly in the operation of fuel cells in vehicles. This ambient air typically needs to be compressed to a specific operating pressure, which can depend on the current power demand of the fuel cell. The final required compression ratio also depends on the ambient air pressure. Especially when driving uphill at altitudes with significantly thinner air, such as over Alpine passes, a single compressor stage is insufficient to provide the required compression ratio. In such cases, an arrangement of at least two compressors connected in series in the direction of airflow is necessary. Disclosure of the invention The invention provides a method for operating an arrangement comprising at least one first compressor and a second compressor for supplying a gaseous operating medium to at least one fuel cell at a predetermined pressure or pressure ratio. In this arrangement, the first and second compressors are connected in series in the direction of flow of the operating medium. The operating medium can, in particular, be ambient air, which serves as the oxidizer for the fuel cell. In addition to the pressure and pressure ratio, the load distribution between the first and second compressors also takes into account other required operating parameters, such as mass flow rate, temperature, and humidity for the air supplied to the cathode path of the respective stack, and mass flow rate in the exhaust gas path for diluting purge gas from the anode path. This means that target values can also be specified for these operating parameters, which must be maintained during operation of the compressor arrangement. These specifications can originate from the fuel cell itself, from a fuel cell stack containing the fuel cell, or from another source, such as the exhaust gas path. The fuel cell can, for example, be part of a fuel cell stack. In such a fuel cell stack, a large number of fuel cells are connected in series to obtain an electrical voltage usable for practical applications. A single fuel cell delivers only a very low voltage, such as a maximum of 1.2 volts for a hydrogen-oxygen cell. For the method proposed here, it is irrelevant whether only a single fuel cell or one or more fuel cell stacks need to be supplied with operating fluids. For the sake of clarity, only one fuel cell downstream of the arrangement consisting of the two compressors will be discussed below. As part of the process, a first compression cycle, to be performed by the first compressor, and a second compression cycle, to be performed by the second compressor, are determined such that, after both compression cycles, the operating fluid has at least the required pressure or pressure ratio relative to its original pressure. "At least" here means that if target values are specified for other operating parameters, these target values must also be met. That is, a pressure and/or a pressure ratio, and optionally other operating parameters, can be specified, and the compression cycles to be performed are determined in such a way that all these specifications are met. The required compression load is therefore initially distributed. This initial distribution can be obtained, for example, from offline simulations and/or previously conducted development tests. If, for example, a pressure ratio is required, the pressure ratio provided by the first compressor and the pressure ratio provided by the second compressor are multiplied by the series connection to form a total pressure ratio for the arrangement, which can then be compared with the requirement. In addition to the requested target pressures for the cathode paths of the stacks and the ambient pressure for determining the overall pressure ratio and its distribution across the compression stages, the pressure losses in the air paths and their components can also be taken into account. the (e.g., pipes, heat exchangers, valves, etc.). This results in a higher overall compression ratio, which the compressor stages are intended to adjust. Operating parameters are determined for the first and second compressors such that both compressors, when operating with their respective parameters, deliver t