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CN-122000380-A - Fuel cell system, method for operating a fuel cell system, and vehicle

CN122000380ACN 122000380 ACN122000380 ACN 122000380ACN-122000380-A

Abstract

The invention relates to a fuel cell system for converting energy, wherein the fuel cell system comprises a fuel cell stack comprising an anode chamber and a cathode chamber, an air system for supplying air to the cathode chamber, wherein the air system comprises a compressor for compressing air, a cathode exhaust gas recirculation system configured for recirculating exhaust gas flowing out of the cathode chamber at least partially through the cathode chamber, wherein the cathode exhaust gas recirculation system comprises a switchable cathode recirculation valve, and a calculation unit configured for opening the cathode recirculation valve when a gas flow to be supplied to the cathode chamber reaches a surge boundary of the compressor.

Inventors

  • J. Brightinger
  • M. HERMAN

Assignees

  • 罗伯特·博世有限公司

Dates

Publication Date
20260508
Application Date
20251106
Priority Date
20241108

Claims (10)

  1. 1. A fuel cell system (100) for converting energy, Wherein the fuel cell system (100) includes: -a fuel cell stack (101) comprising an anode chamber (103) and a cathode chamber (105); -an air system (107) for supplying air to the cathode chamber (105), wherein the air system (107) comprises a compressor (109) for compressing air; -a cathode exhaust gas recirculation system (111) configured for at least partially recirculating exhaust gas flowing out of the cathode chamber (105) through the cathode chamber (105), wherein the cathode exhaust gas recirculation system (111) comprises a switchable cathode recirculation valve (113), and -A calculation unit (115) configured for opening the cathode recirculation valve (113) when the gas flow to be supplied to the cathode chamber (105) reaches a surge boundary of the compressor (109).
  2. 2. The fuel cell system (100) according to claim 1, It is characterized in that the method comprises the steps of, The cathode recirculation valve (113) is arranged in a connection line (125) connecting an exhaust section (121) of the fuel cell system (100) with an air line for supplying air to the cathode chamber (105), Wherein the connection line (125) is part of the cathode exhaust gas recirculation system (111), and Wherein the cathode recirculation valve (113) is configured for: in a first position, the connection line (125) is blocked to prevent the flow of air from the air line from flowing into the exhaust (121) while bypassing the cathode chamber (105), or In a second position, the air flow from the air line is allowed to flow through the connection line (125) into the exhaust (121) and thereby cause an un-restriction of the fluid path downstream of the compressor (109).
  3. 3. The fuel cell system (100) according to claim 1 or 2, It is characterized in that the method comprises the steps of, The cathode recirculation valve (113) can be flown through in both directions, wherein when the air flow to be supplied to the cathode chamber (105) reaches the surge boundary of the compressor (109), the air flow flows in a first direction from an air line for supplying air to the cathode chamber (105) through the cathode recirculation valve (113) to the exhaust part, and Wherein when there is a cathode recirculation demand, an air flow flows in a second direction from the exhaust (121) through the cathode recirculation valve (113) to the air line.
  4. 4. The fuel cell system (100) according to one of the preceding claims, It is characterized in that the method comprises the steps of, The calculation unit (115) is configured for opening the cathode recirculation valve (113) when the gas flow to be supplied to the cathode chamber (105) is so small that a surge boundary of the compressor (109) is reached or a pressure ratio between an input pressure and an output pressure of the compressor (109) is so high that a surge boundary of the compressor is reached.
  5. 5. The fuel cell system (100) according to one of the preceding claims, It is characterized in that the method comprises the steps of, The computing unit (115) is configured for measuring the input pressure of the compressor (109) by means of a pressure sensor arranged in the air line upstream of the compressor (109) in the flow direction or for determining the input pressure of the compressor from the ambient pressure.
  6. 6. The fuel cell system (100) according to one of the preceding claims, It is characterized in that the method comprises the steps of, The fuel cell system (100) further comprises at least one sensor (117) for measuring the pressure and/or the mass air flow and/or the temperature in the air system (107) and/or the exhaust (121).
  7. 7. The fuel cell system (100) according to one of the preceding claims, It is characterized in that the method comprises the steps of, The fuel cell system (100) does not include a bypass path (123) that is attached to the cathode exhaust gas recirculation system (111) and that directly connects the exhaust section (121) to an air line for supplying air to the cathode chamber (105).
  8. 8. The fuel cell system (100) according to one of the preceding claims, It is characterized in that the method comprises the steps of, The computing unit (115) is configured for: Comparing the gas flow supplied to the fuel cell stack (101) with a predetermined operating point in a characteristic curve of the compressor (109), the characteristic curve being based on the pressure ratio between the inlet and the outlet of the compressor (109) and the flow rate of the compressor (109), and The cathode recirculation valve (113) is opened for the case that the gas flow reaches a surge boundary predefined by the characteristic diagram for the predefined operating point.
  9. 9. A vehicle (300), Wherein the vehicle (300) comprises a fuel cell system (100) according to one of claims 1 to 8.
  10. 10. Method (200) for operating a fuel cell system (100), in particular a fuel cell system (100) according to one of the preceding claims 1 to 8, Wherein the method (200) comprises: -opening (205) a cathode recirculation valve (113) of the fuel cell system (100) when the gas flow to be supplied to a cathode chamber (105) of a fuel cell stack (101) of the fuel cell system (100) reaches a surge boundary of a compressor (109) for supplying air to the cathode chamber (105).

Description

Fuel cell system, method for operating a fuel cell system, and vehicle Technical Field The invention relates to a fuel cell system for converting energy, to a method for operating a fuel cell system and to a vehicle having a fuel cell system according to the invention. Background In conventional air systems of fuel cell systems, valves are used to control the flow of air through the air system. Patent document DE 10 2022 210 075 A1 of robusta bosch limited (Robert Bosch GmbH) describes a fuel cell system with a compressor, a cathode exhaust gas recirculation system and a bypass path. Here, in addition to the cathode exhaust gas recirculation system, the bypass path is also used to directly pass air from an air line for supplying the cathode chamber of the fuel cell stack of the fuel cell system to the exhaust portion of the fuel cell system. Disclosure of Invention Within the framework of the proposed invention, a fuel cell system, a method for operating a fuel cell system and a vehicle are proposed. Other features and details of the invention are set forth in the description and drawings. The features and details described in connection with the fuel cell system according to the invention are of course also applicable here in connection with the method according to the invention or the vehicle according to the invention and vice versa, so that the disclosures on the individual inventive aspects always relate to each other or can relate to each other. The invention is particularly useful for providing a possibility to achieve a robust operation of a fuel cell system. Thus, according to a first aspect of the present invention, a fuel cell system for converting energy is presented. The proposed fuel cell system comprises a fuel cell stack comprising an anode chamber and a cathode chamber, an air system for supplying air to the cathode chamber, wherein the air system comprises a compressor for compressing air, a cathode exhaust gas recirculation system configured for recirculating exhaust gas flowing out of the cathode chamber at least partly through the cathode chamber, wherein the cathode recirculation system comprises a switchable cathode recirculation valve, and a calculation unit configured for opening the cathode recirculation valve when an air flow to be supplied to the cathode chamber reaches/violates (verletzen) a surge boundary (Pumpgrenze) of the compressor. The proposed invention is based on the use of a cathode recirculation valve to de-throttle (entdrosseln) the fluid path downstream of the compressor of the fuel cell system. Accordingly, the cathode recirculation valve serves two purposes, on the one hand, for adjusting the recirculation rate of the recirculated cathode exhaust gas and, on the other hand, for conducting air from the air system of the fuel cell system out of the fuel cell stack of the fuel cell system, thereby protecting the compressor of the air system from harmful surge operation and/or ensuring that the air flow through the air system always complies with (einhalten) the surge boundary of the compressor/remains within the surge boundary of the compressor. Since the air from the air system is guided into the exhaust (Abgastrakt) of the proposed fuel cell system using a cathode recirculation valve, an additional air guiding path, for example an additional bypass path, can be dispensed with, which connects a supply line for supplying air to the fuel cell stack or its cathode chamber with the exhaust. Accordingly, the number of openings in the air system and the exhaust portion is reduced to a minimum. Therefore, by the present invention, the probability of occurrence of leakage of the air system or the exhaust portion is minimized, and robust operation of the fuel cell system can be achieved. It may be provided that the cathode recirculation valve is arranged in a connection line which connects the exhaust gas section with an air line for supplying air to the cathode chamber, wherein the connection line is part of the cathode exhaust gas recirculation system, and wherein the cathode recirculation valve is configured for, in a first position, blocking the connection line to prevent a gas flow from the air line (in particular in the case of bypassing the cathode chamber) from flowing through the connection line into the exhaust gas section, or, in a second position, allowing a gas flow from the air line to flow through the connection line into the exhaust gas section and thereby causing an un-throttling of the fluid path downstream of the compressor. By means of a cathode recirculation valve movable between at least two positions, a fluid path located downstream of the compressor in the flow direction can be checked (kontrollieren) such that it can be coupled in fluid communication with the exhaust, and thus de-throttled, if required, i.e. for the gas flow to be supplied to the cathode chamber to reach the surge boundary of the compressor, in particular if the cathode chamber is by