Solid oxide fuel cell system shutdown decay suppression system, method, and vehicle

Abstract

The present application belongs to the technical field of solid oxide fuel cell system. A kind of solid oxide fuel cell system shutdown attenuation inhibition system, method and vehicle are presented.The system includes fuel cell module, protective gas supply module and electronic control unit, by controlling first isolation valve and second isolation valve to close to form closed cavity when shutdown, and execute intelligent pressure maintenance control.Electronic control unit monitors cavity pressure and stack temperature in real time, when pressure is lower than lower threshold, quantitative hydrogen-nitrogen mixed protective gas is input to maintain positive pressure environment, when temperature drops to attenuation minimum limit, pressure maintenance operation is terminated.The present application effectively solves the technical problem that rapid shutdown and anode attenuation inhibition are difficult to be considered in prior art, both rapid completion of shutdown process is realized, and effective protection of anode in high temperature stage is ensured, unnecessary gas consumption is avoided, system reliability and economy are significantly improved, and it is especially suitable for application scenarios such as vehicle with urgent demand for rapid start-stop.

Description

Technical Field

[0001] This invention relates to the field of solid oxide fuel cell system technology, specifically to a shutdown degradation suppression system, method, and vehicle for a solid oxide fuel cell system. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Solid oxide fuel cells (SOFCs) are all-solid-state chemical power generation devices that efficiently and environmentally convert the chemical energy of fuel and oxidant into electrical energy directly at medium to high temperatures. Their anodes typically utilize nickel-based ceramic composite materials, which must be placed in a reducing gas atmosphere during high-temperature operation to maintain the stability of their microstructure and excellent electrochemical catalytic activity. Therefore, effectively protecting the anode from degradation during system shutdown is a key technical aspect ensuring the long-term reliable operation of SOFCs.

[0004] However, existing technologies, to prevent shutdown degradation, generally employ a strategy of continuously supplying fuel to the anode after shutdown, coupled with slow cooling. While this method can maintain a reducing atmosphere, it results in an excessively long shutdown process, failing to meet the urgent needs of rapid start-stop applications such as automotive. The fundamental problem lies in the lack of a technical means to effectively establish and maintain a positive pressure protective environment within the sealed cavity of the anode fuel circuit while achieving rapid shutdown. This makes it difficult for the system to simultaneously achieve the dual goals of rapid shutdown and suppression of high-temperature oxidation degradation. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a shutdown degradation suppression system, method, and vehicle for solid oxide fuel cell systems. By constructing a sealed cavity and implementing intelligent pressure-holding control, it achieves rapid shutdown and effective suppression of anode degradation. Through a dual monitoring mechanism of pressure and temperature, it ensures a positive pressure protection environment is maintained during high-temperature stages, while promptly terminating the pressure-holding operation after the temperature drops to a safe threshold. This avoids unnecessary gas consumption and solves the problem of simultaneously achieving rapid shutdown and degradation suppression.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a shutdown degradation suppression system for a solid oxide fuel cell system.

[0007] A shutdown degradation suppression system for a solid oxide fuel cell system includes: a fuel cell module, a protective gas supply module, and an electronic control unit; The protective gas supply module includes a gas source, a pressure reducing device, a manual valve, a first isolation valve, and a mass flow controller connected in sequence. The output of the mass flow controller is connected to the heat exchange component of the fuel cell module, and the heat exchange component is connected to the anode of the fuel cell module. The anode outlet of the fuel cell module is connected in sequence to a condenser and a second isolation valve. The electronic control unit is electrically connected to the mass flow controller, the first isolation valve, and the second isolation valve. The electronic control unit is configured to control the first isolation valve and the second isolation valve to close after the system shutdown command is triggered, so that the anode gas path of the fuel cell module forms a closed cavity, and to perform pressure holding control of the closed cavity.

[0008] In one implementation of the first aspect of the present invention, performing pressure-maintaining control of the sealed cavity includes: Real-time pressure monitoring of the sealed cavity; If the pressure is greater than or equal to the preset upper limit threshold, the second isolation valve will be opened to release the pressure. If the pressure is less than the preset upper limit threshold and the pressure is less than or equal to the preset lower limit threshold, the first isolation valve is opened, and a certain amount of hydrogen-nitrogen mixed protective gas is introduced into the sealed cavity through the mass flow controller until the pressure reaches the preset upper limit threshold and then the first isolation valve is closed. If the pressure is less than the preset upper limit threshold and greater than the preset lower limit threshold, the stack temperature of the fuel cell module is acquired in real time while pressure holding control is performed. When the stack temperature is lower than the preset minimum decay limit, pressure holding control is stopped; otherwise, pressure holding control continues.

[0009] In one implementation of the first aspect of the present invention, a first pressure sensor is provided on the connecting pipeline between the gas source and the pressure reducing device, and a second pressure sensor is provided on the pipeline between the heat exchange component and the anode. Both the first pressure sensor and the second pressure sensor are connected to the electronic control unit.

[0010] In one implementation of the first aspect of the present invention, a temperature sensor is provided between the anode and the condenser of the fuel cell. The temperature sensor is connected to the electronic control unit. The pressure reducing device is configured to reduce the pressure of the high-pressure hydrogen-nitrogen mixture from the gas source to a safe pressure suitable for the gas circuit of the fuel cell module. The manual valve is a manual shut-off valve used to physically isolate the protective gas supply to the module during system maintenance.

[0011] Secondly, the present invention provides a method for suppressing shutdown degradation in a solid oxide fuel cell system.

[0012] A method for suppressing shutdown degradation in a solid oxide fuel cell system includes the following steps: In response to a system shutdown command, the first isolation valve and the second isolation valve are closed to form a sealed cavity; Real-time pressure monitoring of the sealed cavity; If the pressure is greater than or equal to the preset upper limit threshold, the second isolation valve will be opened to release the pressure. If the pressure is less than the preset upper limit threshold and the pressure is less than or equal to the preset lower limit threshold, the first isolation valve is opened, and a certain amount of hydrogen-nitrogen mixed protective gas is introduced into the sealed cavity through the mass flow controller until the pressure reaches the preset upper limit threshold and then the first isolation valve is closed. If the pressure is less than the preset upper limit threshold and greater than the preset lower limit threshold, the stack temperature of the fuel cell module is acquired in real time while pressure holding control is performed. When the stack temperature is lower than the preset minimum decay limit, pressure holding control is stopped; otherwise, pressure holding control continues.

[0013] In one implementation of the second aspect of the invention, before responding to a system shutdown command, the method further includes performing a safety purging to remove residual fuel in the anode gas path of the fuel cell module.

[0014] In one implementation of the second aspect of the present invention, introducing a fixed amount of hydrogen-nitrogen mixed protective gas includes: calculating the total amount of hydrogen-nitrogen mixed protective gas to be introduced based on the volume of the sealed cavity and the difference between the current pressure and the target holding pressure; accumulating the flow rate of the introduced hydrogen-nitrogen mixed protective gas through a mass flow controller; and stopping the introduction when the accumulated flow rate reaches the total amount.

[0015] In one implementation of the second aspect of the present invention, after stopping the pressure holding control, the method further includes: controlling the second isolation valve to open slowly to smoothly release the residual pressure in the sealed cavity.

[0016] Thirdly, the present invention provides a solid oxide fuel cell system, including the shutdown degradation suppression system of the solid oxide fuel cell system of the first aspect of the present invention.

[0017] Fourthly, the present invention provides a vehicle including the shutdown degradation suppression system of the solid oxide fuel cell system of the first aspect of the present invention; or, including the solid oxide fuel cell system of the third aspect of the present invention.

[0018] Compared with the prior art, the beneficial effects of the present invention are: The solid oxide fuel cell system shutdown degradation suppression system provided by this invention effectively solves the technical challenge of simultaneously achieving rapid shutdown and degradation suppression in existing technologies by constructing a collaborative control architecture composed of a fuel cell module, a protective gas supply module, and an electronic control unit (ECU). Upon triggering a shutdown command, the ECU controls the simultaneous closure of the first and second isolation valves, rapidly forming a sealed cavity in the anode gas path, thus achieving rapid shutdown and significantly shortening system downtime. Furthermore, the ECU executes an intelligent pressure-maintaining control strategy: by real-time monitoring of the sealed cavity pressure, the second isolation valve is opened to release pressure when the pressure exceeds the upper threshold, preventing overpressure risks; when the pressure falls below the lower threshold, a precise metered hydrogen-nitrogen mixed protective gas is precisely introduced through a mass flow controller to maintain a positive pressure reducing environment within the cavity; simultaneously, combined with stack temperature monitoring, the pressure-maintaining operation is terminated promptly after the temperature drops to the minimum degradation threshold. This dual monitoring mechanism ensures effective anode protection during high-temperature stages, preventing oxidation degradation, and also avoids unnecessary gas consumption, achieving an organic unity between rapid shutdown and degradation suppression, significantly improving system reliability and economy.

[0019] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 A schematic diagram of the principle of a shutdown attenuation suppression system for a solid oxide fuel cell system provided as an exemplary embodiment of the present invention; Figure 2 A schematic diagram of a pressure holding control process provided for an exemplary embodiment of the present invention; The components include: 1. Gas source; 2. Pressure reducing device; 3. Manual valve; 4. First isolation valve; 5. Mass flow controller; 6. First pressure sensor; 7. Second pressure sensor; 8. Temperature sensor; 9. Electrical control unit; 10. Condenser; 11. Second isolation valve; and 12. Heat exchange components. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] like Figure 1 The diagram shows a schematic of the degradation suppression system of the present invention, including a fuel cell module (including a heat exchange component 12, a stack body, a second pressure sensor 7, and a temperature sensor 8), a protective gas supply module (including a gas source 1, a first pressure sensor 6, a pressure reducing device 2, a manual valve 3, a first isolation valve 4, and a mass flow controller 5), a heat exchange component 12, a second isolation valve 11, a condenser 10, and an electronic control unit 9. More specifically, the protective gas supply module is connected in series along the airflow direction, consisting of the gas source 1, the first pressure sensor 6, the pressure reducing device 2, the manual valve 3, the first isolation valve 4, and the mass flow controller 5. The mass flow controller 5 is connected to the anode of the fuel cell module through the heat exchange component 12, and the anode outlet is connected to the condenser 10, and then to the second isolation valve 11. The electronic control unit 9 is electrically connected to each sensor and valve.

[0025] The overall system architecture of this invention is based entirely on the integrated expansion design of the original gas supply main circuit of the solid oxide fuel cell module. While retaining the original core structure of fuel supply, oxidant supply, cooling cycle and power generation control, an independent, closed and fully controlled protective gas supply module structure is added. The protective gas supply module is combined with the original gas circuit in a parallel fluid connection. The output end of the protective gas supply module is precisely connected to the gas inlet node of the anode side of the fuel cell module. The input end of the protective gas supply module is independently configured with a dedicated protective gas source unit. Thus, an auxiliary protective gas circuit system is constructed that is completely independent of the fuel supply system under normal power generation conditions and is dedicated to anodizing protection during system shutdown.

[0026] The complete protection system of this invention forms a complete, reliable, and stable electrical, signal, and fluid connection with the fuel cell module body, the original gas pipeline, the cooling circulation pipeline, the vehicle electrical system, and the dedicated electronic control unit 9. After the system triggers a shutdown command, it can automatically, quickly, accurately, and stably deliver a hydrogen-nitrogen mixed protective gas of a specified ratio to the anode side of the fuel cell, continuously maintaining a high concentration of reducing gas atmosphere on the anode side. At the same time, it implements real-time monitoring, dynamic adjustment, and stable maintenance of the internal pressure of the gas circuit through a closed-loop control strategy. This fundamentally solves a series of technical problems in solid oxide fuel cells under high-temperature shutdown conditions, such as oxidation, cracking, activity decay, performance degradation, and shortened lifespan due to the loss of reducing gas protection at the anode.

[0027] In this implementation, gas source 1 serves as the sole storage and supply carrier for protective gas. It adopts a high-pressure sealed tank structure design, with the tank body being integrally forged from high-strength aerospace-grade alloy material. The tank body has uniform wall thickness, high strength, and extremely strong impact resistance, fatigue resistance, and deformation resistance, enabling it to withstand long-term storage of high-pressure gas and vibration impacts during vehicle operation. The tank body is equipped with anti-vibration baffles and gas guiding structures to prevent violent gas swaying, impact on the tank wall, and impact on output stability during vehicle operation. The tank body is equipped with a protective shell, a heat insulation layer, and a shock-absorbing pad. The protective shell is made of high-strength engineering plastic, the heat insulation layer is made of high-temperature resistant heat insulation cotton, and the shock-absorbing pad is made of high-elasticity rubber, further enhancing safety and stability.

[0028] Optionally, in other implementations, the top of the gas source 1 is equipped with an inflation port, a pressure relief valve, and a pressure gauge. The inflation port is used to replenish the protective gas, the pressure relief valve is used for overpressure protection, and the pressure gauge is used to visually display the pressure inside the tank. The output end of the gas source 1 is directly and sealed to the input end of the first pressure sensor 6 through a dedicated high-pressure rigid metal pipeline. The connection position is equipped with a double sealing structure and anti-loosening fasteners to eliminate any risk of minor leakage. The gas source 1 is pre-filled with hydrogen and nitrogen protective gas mixed in a specific ratio. The gas is uniformly mixed, has stable composition, and is free of stratification, impurities, and moisture, and can stably supply protective gas for a long period of time.

[0029] In this implementation, the first pressure sensor 6 is a high-precision, wide-temperature-range, anti-interference, and long-life pressure detection element. It integrates a high-sensitivity pressure-sensitive chip, signal amplification circuit, temperature compensation circuit, filtering circuit, and signal output interface. It can collect the output pressure of the gas source 1 and the remaining gas in the tank in real time, accurately, and stably. The measurement range covers the entire pressure range of the protective gas, and the measurement accuracy reaches the industry-leading level. It can work stably for a long time in a wide temperature range of -40℃ to 150℃, strong electromagnetic interference, and high-frequency vibration environment, with minimal drift and high reliability.

[0030] The first pressure sensor 6 establishes a bidirectional electrical connection with the electronic control unit 9 via a dedicated shielded signal cable. The shielded cable effectively isolates electromagnetic interference, ensuring stable and distortion-free signal transmission. It converts the acquired analog pressure signal into a standard digital signal in real time and transmits it to the electronic control unit 9, providing core, reliable, and continuous data support for subsequent pressure reduction regulation, flow control, pressure closed-loop regulation, and fault diagnosis. The first pressure sensor 6 is installed close to the output end of the gas source 1, enabling it to capture minute fluctuations in the output pressure of the gas source 1 immediately, avoiding signal delays that could lead to control deviations, and ensuring the timeliness, accuracy, and stability of the entire protection system's control response.

[0031] In this implementation, the pressure reducing device 2 is a multi-stage series precision pressure regulating structure, internally integrating multi-stage pressure reducing valve cores, pressure feedback loops, flow stabilization components, safety relief valves, pressure display interfaces, and fault detection interfaces. The entire device is made of high-temperature resistant stainless steel, featuring a precise structure, high pressure resistance, and good stability. The pressure reducing device 2 receives the high-pressure hydrogen-nitrogen mixture from the gas source 1 at its input end. Through the multi-stage pressure reducing valve cores, it gradually, smoothly, and precisely reduces the gas pressure, avoiding pressure surges, shocks, and fluctuations caused by single-stage pressure reduction. It accurately regulates the high-pressure protective gas to a low-pressure range perfectly suited for the safe operation of the fuel cell gas circuit, achieving high regulation accuracy and minimal pressure fluctuations.

[0032] The pressure feedback loop inside the pressure reducing device 2 can monitor the output pressure in real time. When the output pressure deviates slightly due to fluctuations in the pressure of the gas source 1, changes in flow rate, or changes in ambient temperature, it automatically, quickly, and accurately adjusts the valve core opening for dynamic compensation, ensuring that the output pressure is always stable within the preset minimum error range. This effectively prevents high-pressure gas from directly impacting the fuel cell pipeline, seals, stack flow channels, and individual cells, causing structural damage, performance degradation, and shortened lifespan.

[0033] The input end of the pressure reducing device 2 is fixedly connected to the output end of the first pressure sensor 6 through a sealed pipeline. The output end of the pressure reducing device 2 is tightly connected to the input end of the hand valve 3 through a high-temperature and corrosion-resistant threaded sealing structure. The threaded connection is wrapped with multiple layers of high-temperature and aging-resistant sealing tape, and is used in conjunction with a special fluororubber sealing gasket to further enhance the sealing effect and prevent gas leakage.

[0034] In this implementation, the hand valve 3 is a manually controlled shut-off valve. The valve body is made of high-temperature resistant, corrosion-resistant, and high-strength stainless steel through precision casting. The valve core is made of hard alloy material through precision machining. The valve stem adopts an anti-rotation and anti-jamming structure design. The sealing surface is precision ground, resulting in excellent sealing performance.

[0035] The hand valve 3 features a robust, wear-resistant, and anti-aging design with excellent sealing performance. It can operate continuously in environments with temperatures ranging from -20℃ to 180℃, high pressure, and high-frequency vibration without jamming or leakage. The operating handle of the hand valve 3 extends to a designated position on the fuel cell system maintenance panel. The handle is ergonomically designed for comfortable grip and effortless operation, allowing operators to quickly, easily, and accurately perform manual opening and closing operations during system inspection, maintenance, component replacement, or emergency situations.

[0036] Hand valve 3 remains open during normal system operation and protection conditions, ensuring that protective gas can flow smoothly and normally to the protective gas supply module. When the system needs to be disassembled, repaired, or the protective gas source 1 needs to be replaced, troubleshooting is required, or a major abnormal condition occurs, the handle can be manually rotated to quickly and completely close hand valve 3, forcibly cutting off the protective gas supply path and achieving physical isolation between the protective gas supply module and the fuel cell system, thus eliminating the safety risks caused by gas leakage and misoperation from the source. Hand valve 3 has three functions in the protective gas supply module: manual on / off, safety isolation, and maintenance, and is an important component of the safety design of the entire protection system.

[0037] In this implementation, the first isolation valve 4 is an electromagnetically driven high-precision electrically controlled switch valve. The valve body is made of high-temperature resistant, insulating, and anti-aging engineering plastic molding, which has good insulation performance, high temperature resistance, and is not easy to age. The valve core is made of highly elastic, anti-aging, low-temperature resistant, and corrosion-resistant fluororubber material, which has excellent sealing performance and can achieve zero leakage. The valve seat is made of wear-resistant alloy material, which is wear-resistant and has a long service life.

[0038] The first isolation valve 4 has an extremely fast overall response speed, with opening and closing times in the millisecond range. It has extremely low power consumption, stable and reliable operation, and can work for a long time in a wide temperature range, vibration, and electromagnetic interference environment. The first isolation valve 4 establishes a reliable and stable electrical connection with the output terminal of the electronic control unit 9 through a dedicated high-temperature resistant and bend-resistant control cable. The cable is made of flame-retardant material, which is resistant to aging and not easy to break, and accurately receives the on / off control electrical signals sent by the electronic control unit 9.

[0039] The input end of the first isolation valve 4 and the output end of the hand valve 3 are flexibly connected via a high-strength, aging-resistant, and vibration-resistant sealing hose. The sealing hose employs a multi-layer composite structure, with an inner corrosion-resistant layer and an outer aging-resistant layer, possessing excellent flexibility, fatigue resistance, and sealing performance. It effectively absorbs vibration, impact, and displacement during vehicle operation, preventing pipe breakage, seal failure, and gas leakage. The output end of the first isolation valve 4 and the input end of the mass flow controller 5 are rigidly connected via a high-strength sealing flange. The flange is made of stainless steel, with precision-machined connection surfaces and fitted with high-temperature, high-pressure, and corrosion-resistant special fluororubber gaskets. High-strength bolts are then evenly tightened to ensure a secure connection, tight sealing, and no leakage.

[0040] In this implementation, the mass flow controller 5 is a high-precision, intelligent, wide-range gas flow control element. It integrates a high-precision flow detection sensor, an electromagnetic flow regulating solenoid valve, a microcontroller circuit board, a signal processing circuit, a communication interface, a fault detection circuit, and a temperature compensation circuit. The outer shell is made of aluminum alloy, which has good heat dissipation and anti-interference properties.

[0041] The mass flow controller 5 covers the commonly used flow range of protective gases, offering extremely high measurement and control accuracy. It can detect the instantaneous flow rate, cumulative flow rate, and velocity of the protective gas in real time, with rapid response, good stability, and minimal long-term drift. Based on the flow setting command issued by the electronic control unit 9, the mass flow controller 5 can dynamically, quickly, and accurately adjust the opening of the solenoid valve to achieve closed-loop precise control of the protective gas flow rate. This ensures that the protective gas is delivered stably, uniformly, and without pulsation at the set flow rate, without flow fluctuations or impacts. The mass flow controller 5 possesses outstanding advantages such as strong anti-interference capability, high temperature resistance, and wide adaptability. It can perfectly adapt to the flow control requirements of hydrogen-nitrogen mixed protective gases and is also compatible with various inert and reducing gases.

[0042] In this implementation, the mass flow controller 5 establishes a bidirectional high-speed data communication connection with the electronic control unit 9 via a dedicated shielded communication cable. It provides real-time feedback of flow data, operating status, fault information, and temperature information, while simultaneously receiving flow setpoints, control commands, and calibration commands from the electronic control unit 9. Communication is stable and data transmission is reliable. The output of the mass flow controller 5 is precisely and sealed to the anode-side gas inlet of the fuel cell module via a high-temperature, high-pressure resistant metal rigid pipe. The pipe uses seamless steel tubing and is welded and sealed to ensure that all protective gas is delivered to the anode channel without loss, diversion, or dead zones, guaranteeing a uniform, stable, and fully covered protective atmosphere on the anode side.

[0043] At the gas outlet of the fuel cell module, an additional independent second isolation valve 11 is installed. This second isolation valve 11 is an electromagnetically driven electrically controlled valve of the same model, specification, material, performance, and control method as the second isolation valve 11 used in the protective gas supply module. The two are completely consistent in structural design, material selection, sealing performance, response speed, operating temperature range, and electrical parameters to ensure synchronous operation, performance matching, and reliable control.

[0044] The input end of the second isolation valve 11 at the gas circuit outlet is connected to the gas circuit outlet of the fuel cell module with a high-precision seal via a high-temperature resistant and corrosion-resistant sealing pipeline. The pipeline is welded and fixed, ensuring good sealing performance. The outlet of the condenser 10 is connected to the inlet of the second isolation valve. The condenser 10 adopts a shell-and-tube structure to cool the exhaust gas and prevent high-temperature gas from affecting subsequent components. This forms a complete, controllable, and sealable pressure control loop at the end of the fuel cell module's gas circuit, allowing for flexible control of gas circuit opening and closing and pressure release. The second isolation valve 11 is also electrically connected to the output end of the electronic control unit 9 via a dedicated control cable. Under the unified, coordinated, and synchronous control of the electronic control unit 9, it works in conjunction with the various functional components of the protective gas supply module to jointly complete a series of operations, including supplying protective gas inside the fuel cell gas circuit, constructing a sealed cavity, maintaining pressure, dynamically adjusting, and releasing gas. The coordinated linkage between the two is the core hardware foundation for achieving stable closed-loop control of system pressure, ensuring a positive pressure reducing atmosphere on the anode side, and suppressing oxidation degradation.

[0045] The electronic control unit 9, as the core control hub of the entire shutdown attenuation suppression system, uses an industrial-grade, highly reliable, anti-interference, and high-temperature resistant embedded microprocessor as its core computing unit. The processor boasts a high clock speed, fast processing speed, and powerful processing capabilities. Internally, the electronic control unit 9 integrates a high-speed multi-channel data acquisition module, an intelligent control computing module, a high-precision instruction output driver module, a large-capacity non-volatile storage module, a multi-protocol communication interface module, a fault diagnosis module, a power management module, and a temperature monitoring module. These functional modules achieve high-speed data interaction, rapid instruction transmission, and real-time status synchronization through a high-speed, stable, and anti-interference internal bus. The bus has high bandwidth, strong anti-interference capabilities, and stable and reliable data transmission.

[0046] The electronic control unit 9 establishes high-precision data acquisition connections with the first pressure sensor 6, the second pressure sensor 7, the temperature sensor 8, and the mass flow controller 5 through multiple sets of shielded signal cables. It collects key operating parameters such as system pressure, temperature, flow rate, and gas source 1 inventory in real time, continuously, and at high frequency, with high sampling frequency and high data accuracy. The electronic control unit 9 also establishes reliable control output connections with the first isolation valve 4 of the protective gas supply module and the second isolation valve 11 of the gas circuit outlet through multiple sets of high-temperature resistant and bend-resistant control drive cables. It has strong output drive capability and fast action response. The electronic control unit 9 also establishes bidirectional data interaction connections with the vehicle control system and the fuel cell main control system through an industrial-grade high-speed communication bus. The communication protocol is universal and has good compatibility. It receives system emergency stop commands and operating mode commands issued by the vehicle in real time, and simultaneously feeds back the operating status, key parameters, fault information, and execution results of the protection system.

[0047] The electronic control unit 9 internally stores a shutdown protection control program, various operating parameter thresholds, fault diagnosis logic, emergency handling strategies, calibration data, and historical operating data, all of which have undergone extensive bench testing, real-vehicle verification, multi-condition optimization, and long-term operational iteration. The program boasts rigorous logic, strong fault tolerance, and high stability. Based on real-time collected operating data and the preset control program, it can automatically, quickly, and accurately execute logical operations, control decisions, command issuance, and status feedback, achieving fully automated, intelligent, and unmanned operation of the entire shutdown protection process without human intervention, manual operation, or on-site intervention. The electronic control unit 9 is externally encased in a metal shell, providing electromagnetic interference resistance, excellent heat dissipation, and adaptability to the complex electromagnetic environment of an automotive vehicle.

[0048] like Figure 2 The diagram shows the attenuation suppression control process. Triggered by a system shutdown command, the system first determines the required flow rate of protective gas based on the system status, then enters the system pressure holding stage. During this process, the system continuously performs pressure closed-loop judgment. When the system pressure P is found to be below (upper limit ± threshold), the second isolation valve 11 is opened to release pressure, and the system returns to the pressure holding state. When the system pressure meets P < upper limit ± threshold, the system further judges whether the system pressure meets P > (lower limit ± threshold). If not, the first isolation valve 4 is opened to introduce protective gas, and the system returns to the pressure holding state again. When the system pressure simultaneously meets both the upper and lower limit judgment conditions, the system temperature is judged. If the fuel cell temperature T is not below (set value ± threshold), the system pressure holding continues, and the above pressure closed-loop judgment process is repeated. When the system temperature T meets T < (set value ± threshold), the process ends, and the protection action is completed. The control process is logically rigorous, timing precise, and responsive. It performs closed-loop regulation around the two core parameters of system pressure P and temperature T throughout the process, ensuring the stability of the protective atmosphere on the anode side during shutdown, while avoiding the ineffective consumption of protective gas. It is fully adapted to the actual needs of suppressing shutdown degradation of solid oxide fuel cells.

[0049] In this implementation, after the system emergency stop response phase is completed and all components have performed normal self-checks and are fault-free, the process automatically enters the safety purging preparation phase. The electronic control unit 9 first checks the status of the purging gas supply device, confirming that the purging gas pressure is sufficient, the flow rate is normal, the supply valve is in the correct open / closed position, and the purging gas is high-purity nitrogen, meeting purity standards and free of impurities. It then checks the mechanical and electrical control status of the existing gas circuit inlet and outlet valves, confirming that the valves can open and close normally without jamming or leakage. Next, it checks the connection, power supply, and signal status of the residual gas concentration sensor, confirming that the sensor is working normally and can accurately collect residual fuel concentration data in real time. Finally, it checks the status of the cooling system, confirming that the cooling medium circulation is normal and can assist in controlling the purging temperature. Finally, it checks the internal purging-related parameter configuration of the electronic control unit 9, confirming that the thresholds are reasonable and the logic is correct.

[0050] After all preparatory checks are passed without any abnormalities, the process proceeds to the safety purging execution phase. Safety purging is an essential and crucial pre-shutdown safety procedure for fuel cell systems. Its core purpose is to thoroughly, cleanly, and completely remove residual hydrogen or hydrogen-rich fuel from the anode flow channels, fuel distribution chambers, existing gas pipelines, connecting pipelines, and related accessories of the fuel cell module. This prevents residual fuel from coming into contact with air in the high-temperature environment of the fuel cell stack, which could lead to major safety accidents such as combustion, explosion, backfire, or flash explosion. At the same time, it prevents residual fuel from mixing with subsequent protective gases, reducing the purity of the protective gases, affecting the effectiveness of the protective atmosphere, preventing side reactions between residual fuel and protective gases, and ensuring the safety and stability of the protection process.

[0051] After the safety purging phase is initiated, the electronic control unit 9 fully opens the original gas circuit inlet and outlet valves, ensuring a complete purging path. It then activates the purging gas supply device, continuously, stably, and uniformly introducing high-purity nitrogen into the gas circuit at a preset flow rate and pressure. The purging gas flows forward along the gas circuit, from the inlet to the outlet, thoroughly and completely replacing and cleaning the entire fuel circuit, removing residual fuel. During the purging process, the electronic control unit 9 continuously and frequently monitors the residual fuel concentration in the gas discharged from the gas circuit outlet using a residual gas concentration sensor, sampling multiple times per second and continuously performing the purging operation, updating the concentration data in real time. When the residual fuel concentration is consistently below the preset safety threshold for multiple consecutive sampling cycles, and the purging time reaches the preset minimum effective purging time, both conditions are simultaneously met, indicating that the purging is completely complete and there is no residual fuel. The electronic control unit 9 automatically shuts off the purging gas supply device and related valves, stopping the purging action. The safety purging phase ends, and the process automatically jumps to the protective gas introduction preparation phase.

[0052] During the protective gas introduction preparation stage, the electronic control unit 9 checks the status of each component in the protective gas circuit item by item: It checks the pressure and quantity of the protective gas source 1, confirming sufficient gas, normal pressure, no leaks, and no abnormalities; it checks the output pressure of the pressure reducing device 2, confirming stable pressure, compliance with the set value, and normal adjustment; it checks the electrical connection and mechanical status of the first isolation valve 4 of the protective gas supply module, confirming that the valve can open and close normally, without jamming or leaks; it checks the power supply, communication, and flow calibration status of the mass flow controller 5, confirming normal operation and accurate flow control; it checks the status of the second isolation valve 11 at the gas circuit outlet, confirming that it is in the closed position and has a good seal; it checks the status of the second pressure sensor 7 and temperature sensor 8 on the anode side, confirming that they can collect data normally; and it checks the relevant parameters for protective gas introduction inside the electronic control unit 9, confirming that the flow rate, total quantity, and ratio settings are reasonable. After all preparation items pass the verification and there are no faults or abnormalities, the process enters the protective gas quantitative introduction stage. This stage is the core, key, and decisive link in the entire shutdown protection process. It directly determines the quality of the reducing protective atmosphere construction on the anode side, the protection effect, and the attenuation suppression capability. The accuracy, stability, and uniformity of the introduction process directly affect the success or failure of the protection.

[0053] After the protective gas metering phase is initiated, the electronic control unit 9 first sends an opening command to the first isolation valve 4 of the protective gas supply module. The electromagnetic coil is energized, and the valve core opens rapidly, opening the protective gas supply path. At the same time, it sends a preset flow command to the mass flow controller 5 to activate the flow control function and set the target flow value. The hydrogen-nitrogen mixture output from the protective gas source 1 is depressurized and stabilized by the pressure reducing device 2 and then flows into the mass flow controller 5 through the opened isolation valve. The mass flow controller 5 adjusts the opening of the electromagnetic valve in real time according to the set flow rate, accurately, stably, and uniformly delivering the protective gas with minimal flow fluctuations and smooth delivery. The protective gas flows rapidly into the gas inlet of the fuel cell module anode side along the high-temperature resistant pipeline, quickly diffuses and fills the entire anode flow channel, and is evenly distributed along the flow field plate, forming a uniform, stable, and high-concentration reducing protective atmosphere on the anode surface. This completely blocks air infiltration, isolates oxygen contact, and eliminates the conditions for oxidation reaction. Hydrogen in the protective gas provides reducing properties, while nitrogen dilutes the concentration, improves safety, and assists in cooling.

[0054] The protective gas supply adopts a strict quantitative control mode. The electronic control unit 9 accurately calculates the total amount of protective gas required based on the anode flow channel volume, gas pipeline volume, target pressure holding pressure, and protective gas concentration to avoid excessive or insufficient supply affecting the protection effect. The mass flow controller 5 accumulates the total amount of protective gas supplied in real time and updates the accumulated data every second. When the accumulated flow reaches the preset total threshold, the supply is immediately determined to be over. The electronic control unit 9 then issues a stop delivery command, shuts off the output of the mass flow controller 5, and simultaneously issues a shutdown command to close the first isolation valve 4 of the protective gas supply module, cutting off the protective gas supply. The quantitative supply stage of protective gas ends, and the process automatically jumps to the system pressure holding preparation stage.

[0055] During the system pressure holding preparation phase, the electrical control unit 9 checks the electrical and mechanical status of the first isolation valve 4 at the front end of the mass flow controller 5 and the second isolation valve 11 at the rear end of the condenser 10 to confirm that the valves can close quickly and tightly and have good sealing performance; it checks the status of the second pressure sensor 7 on the anode side to confirm that it can monitor the pressure of the sealed cavity in real time and accurately; it checks the internal pressure holding parameters of the electrical control unit 9 to confirm that the upper and lower pressure thresholds are reasonable and the control logic is correct; and it confirms that the protective gas introduction has been completed and the anode side is full of protective gas.

[0056] After all preparations are complete, the process enters the system pressure holding stage. The electronic control unit 9 synchronously, rapidly, and precisely sends closing commands to the first isolation valve 4 upstream of the mass flow controller 5 and the second isolation valve 11 downstream of the condenser 10. Both isolation valves operate simultaneously and close tightly, ensuring that the fuel cell module's gas path, anode flow path, and connecting pipes together form a completely sealed cavity structure with no leakage channels. The previously introduced quantitative hydrogen-nitrogen mixed protective gas is sealed within the sealed cavity, preventing leakage and naturally forming a stable positive pressure environment within the cavity. This positive pressure, higher than the external atmospheric pressure, effectively prevents outside air from seeping into the anode side through pipe gaps, fuel cell stack sealing strip gaps, and minute gaps in component connections, fundamentally eliminating contact between oxygen and the anode active material and completely blocking the oxidation reaction pathway. During the pressure holding process, the electronic control unit 9 monitors the pressure changes inside the sealed cavity in real time and at high frequency through the second pressure sensor 7, sampling multiple times per second to confirm that the pressure is stable within the preset pressure holding range, without abnormal fluctuations or rapid drops, thus determining that the pressure holding is stable and the seal is good; after the pressure holding is stable, the process enters the pressure closed-loop dynamic adjustment stage and enters the continuous protection cycle.

[0057] The pressure closed-loop dynamic adjustment stage is the core of the continuous maintenance of the entire protection process. On the basis of stable pressure, through real-time pressure monitoring and dynamic gas replenishment and pressure stabilization, the positive pressure and protective atmosphere of the sealed cavity are continuously maintained, compensating for minor leaks and ensuring that the anode side is in a safe reducing environment for a long time. The electronic control unit 9 monitors the internal pressure of the sealed cavity in real time, continuously and uninterruptedly at a high-frequency sampling frequency, establishes a real-time pressure data curve, and compares the current pressure with the preset threshold in real time: when the pressure of the sealed cavity is detected to be higher than the preset upper limit threshold, it is determined that the pressure is too high and there is a safety risk. The electronic control unit 9 briefly opens the second isolation valve 11 at the gas circuit outlet to release a small amount of protective gas. After the pressure quickly drops back to the normal range, the second isolation valve 11 is immediately closed to avoid damage to the pipeline and seals due to excessive pressure. When the pressure of the sealed cavity is detected to be lower than the preset critical pressure value, it is determined that there is a slight leak in the cavity, the protective gas is slowly lost, the concentration of the protective atmosphere on the anode side decreases, the positive pressure weakens, and the oxidation risk increases, immediately triggering the low-pressure gas replenishment process.

[0058] After the gas replenishment process is initiated, the electronic control unit 9 opens the first isolation valve 4 at the front end of the mass flow controller 5, opening the gas replenishment path; the mass flow controller 5 is activated to deliver protective gas at a preset gas replenishment flow rate, quickly replenishing the gas reserves in the chamber and increasing the pressure; the pressure recovery process is monitored in real time, and when the pressure recovers to the preset upper limit threshold, gas replenishment is immediately stopped, all isolation valves are closed, and the pressure holding state is re-entered. This closed-loop logic of "pressure monitoring - high pressure relief / low pressure replenishment - re-pressure holding" is executed continuously, repeatedly, and uninterruptedly, dynamically compensating for leakage losses, maintaining the chamber pressure stable within a safe range, and continuously ensuring a positive pressure reducing atmosphere on the anode side until the stack temperature drops to a safe level. The entire process is uninterrupted, without delay, and without manual intervention, with rapid response, precise adjustment, and high stability.

[0059] Throughout the continuous operation of the pressure closed-loop dynamic regulation phase, the electronic control unit 9 simultaneously enters the real-time temperature monitoring and linkage control phase. Temperature monitoring and pressure regulation are executed in parallel, without interference and in close coordination. The electronic control unit 9 continuously monitors the core temperature of the fuel cell stack in real time through the high-precision temperature sensor 8, sampling multiple times per second and generating a temperature drop curve in real time to accurately track temperature change trends. The preset minimum decay limit is the critical temperature at which the oxidation activity of the anode material is significantly reduced and the oxidation risk is negligible. When the real-time temperature of the stack is higher than the minimum decay limit, it is determined that the oxidation activity of the anode material is strong and the oxidation risk is high. The protective atmosphere and positive pressure environment must be maintained continuously, and the pressure closed-loop regulation process continues to run without interruption. When the system detects that the real-time temperature of the stack is lower than the minimum decay limit and remains stable below this temperature for a period of time, it is determined that the oxidation reaction of the anode material has basically stopped and the oxidation risk has dropped to a safe level. It is no longer necessary to maintain the protective gas atmosphere and system pressure. The electronic control unit 9 automatically triggers the shutdown exit preparation process, and the protection process can be safely exited, avoiding ineffective consumption of protective gas and improving system economy.

[0060] During the shutdown exit preparation phase, the electronic control unit 9 confirms that the fuel cell stack temperature has reached the standard and the oxidation risk has been eliminated; confirms that the system pressure is within the normal range and there are no abnormalities; and confirms that all protection actions have been completed without faults. After the preparation phase is completed, the shutdown exit execution phase begins. The electronic control unit 9 first issues a closing command to the first isolation valve 4 of the protective gas supply module to completely cut off the protective gas supply path and prevent gas from continuing to flow in and causing waste. Then, it slowly and controllably opens the second isolation valve 11 at the gas circuit outlet to release the residual protective gas in the sealed cavity in stages and smoothly, strictly controlling the depressurization rate to avoid pipeline impact, fuel cell stack vibration, or pressure fluctuations caused by rapid depressurization, thus protecting the safety of system components. After depressurization is completed, the system pressure drops to atmospheric pressure, and the electronic control unit 9 sequentially shuts off the power supply to all sensors, controllers, and actuators, cutting off system energy consumption and entering a low-power standby mode. After completing all shutdown exit actions, the system enters a complete shutdown standby state, waiting for the next start command to trigger. The entire shutdown attenuation suppression process is successfully completed, with safety, stability, and reliability throughout, and significant protection effect.

[0061] The hydrogen-nitrogen mixed protective gas serves as the core protective medium. Its ratio has been optimized through extensive testing and real-vehicle verification, balancing reducibility, safety, thermal conductivity, and economy. Hydrogen, as the core reducing component, possesses extremely strong reducing capabilities, rapidly eliminating trace oxidizing impurities on the anode surface, blocking oxidation chain reactions, and protecting the anode active material. Nitrogen, as an inert diluent component, is chemically stable, non-flammable, and highly safe, effectively reducing the hydrogen concentration in the mixture, lowering the risk of flammability and explosion, and improving system safety. Simultaneously, nitrogen's excellent thermal conductivity helps remove localized high temperatures on the anode side, further suppressing the high-temperature oxidation reaction rate. The mixture ratio is tailored to the characteristics of the solid oxide fuel cell anode material and the shutdown temperature range, maximizing safety, reducing costs, and extending the range of gas source 1 while ensuring effective reduction and protection.

[0062] In this implementation, high-purity nitrogen is used as the purging medium for safety purging. The purity of the nitrogen is strictly controlled at an extremely high level, with no oxygen, impurities, or moisture. This prevents residual oxygen from entering the anode and causing secondary oxidation, or impurities from contaminating the fuel cell stack flow channels. The purging flow rate, purging time, and purging pressure are precisely set according to the fuel cell specifications, pipeline volume, and residual fuel characteristics to ensure efficient, thorough, and residue-free purging, eliminating safety hazards and creating a clean environment for the subsequent introduction of protective gas.

[0063] In this implementation, during the quantitative protective gas introduction stage, the flow control is highly precise and the quantity is accurate, accurately matching the cavity volume and pressure holding requirements to avoid gas waste or insufficient protection. The introduction process is stable and uniform, with the protective gas evenly distributed in the anode channel, without localized low concentrations, ensuring full coverage of the protective atmosphere without dead zones. During the system pressure holding stage, the sealed cavity has strong sealing performance, and the multiple sealing design of the first isolation valve 4 and the second isolation valve 11 results in extremely low leakage, stable and persistent positive pressure, and effective isolation from external air, eliminating oxidation pathways at the source. In the pressure closed-loop regulation stage, the response is rapid, the regulation is precise, and the fluctuations are small, allowing for real-time compensation for minor leaks, maintaining stable pressure, and ensuring a continuous and reliable protective atmosphere, adapting to various operating conditions such as long-term vehicle shutdown or short-term parking. Through temperature-linked control, the oxidation risk inflection point is accurately captured, and the intelligent start-stop protection process balances protection effectiveness and economy, avoiding ineffective energy consumption and gas consumption. During the shutdown and exit process, the pressure relief is stable, the power disconnection is orderly, and the system is safe and reliable, protecting system components, preparing for the next startup, and extending the system's service life.

[0064] In summary, this invention designs a fuel cell shutdown degradation protection and suppression system with comprehensive fault diagnosis, alarm, and emergency protection functions. It can achieve rapid system shutdown by introducing protective gas into the anode, meeting the rapid start-up and shutdown requirements of vehicle-mounted systems. Furthermore, it utilizes system pressure for closed-loop control, calculating the flow rate of the protective gas to achieve precise control. It can monitor component status in real time, quickly identify faults, and automatically trigger emergency strategies to ensure system operational safety. This invention effectively solves the problem of high-temperature shutdown and anode oxidation in solid oxide fuel cells, significantly suppressing degradation and extending stack lifespan. It fully meets the practical application requirements of rapid start-up and shutdown, efficient protection, stable operation, and safe and reliable operation of on-board solid oxide fuel cells, possessing extremely high engineering application value and promising prospects for industrial promotion.

[0065] This implementation also proposes a solid oxide fuel cell system that integrates the aforementioned shutdown degradation suppression system. This system can be used as an independent power generation unit or range extender and can be applied to various stationary or mobile scenarios.

[0066] For example, it can be used as a fixed backup power source, and the system can be deployed in data centers, communication base stations, or home energy stations. In the event of a grid power outage, the system quickly starts to provide emergency power. When mains power is restored or a shutdown command is triggered upon completion of the task, its built-in shutdown attenuation suppression system immediately activates. By constructing a sealed cavity and implementing pressure-holding control, it ensures that the fuel cell anodes are effectively protected even when unattended, extending the lifespan and reliability of the backup power source.

[0067] For example, it can be used as a distributed generation unit in microgrids or combined heat and power (CHP) systems, where the fuel cell system can be started and stopped according to energy demand. Frequent scheduling operations pose a significant challenge to the lifespan of the fuel cell stack. The shutdown degradation suppression system of this invention can effectively cope with this operating condition by automatically executing a protection program after each shutdown, solving the problem of rapid performance degradation caused by frequent start-stop operations and ensuring long-term operational economy.

[0068] This implementation also proposes a vehicle that, by integrating the aforementioned solid oxide fuel cell system or its shutdown degradation suppression system, is particularly suitable for transportation applications with high requirements for driving range, refueling convenience, and system durability. Different types of vehicle application scenarios present different needs for shutdown protection strategies, and the system of this invention can be flexibly adapted to the following vehicles.

[0069] Example 1: Heavy commercial vehicles (such as long-haul trucks and city buses).

[0070] Scenario 1: Rest stops or overnight parking. Drivers may stop for several hours or even overnight at service areas or terminals. During this time, the fuel cell stack remains at a high temperature, making it highly susceptible to anodic oxidation and degradation. The system of this invention automatically activates after the vehicle is turned off, forming a sealed positive pressure chamber and continuously monitoring the pressure and temperature. This allows the vehicle to maintain the fuel cell stack in good condition even after long periods of parking, enabling "stop and go" without the need for lengthy preheating or purging processes, greatly improving operational efficiency.

[0071] Scenario 2: Hydrogen / Gas refueling station refueling. During refueling, the vehicle needs to be completely shut down. This system ensures that the high-temperature fuel cell stack is effectively protected during the brief refueling intervals, avoiding cumulative damage caused by frequent short shutdowns.

[0072] Example 2: Special-purpose vehicles (such as port AGVs, mining transport vehicles, and airport tractors): These vehicles typically operate continuously in enclosed or semi-enclosed areas, requiring frequent starts and stops. Traditional shutdown protection methods are too time-consuming, severely impacting the work cycle. The rapid shutdown attenuation suppression system of this invention perfectly meets this need, completing shutdown protection actions within tens of seconds, enabling vehicles to quickly respond to the next dispatch command and ensuring the continuity of logistics and production.

[0073] Example 3: Passenger vehicles (such as sedans and SUVs).

[0074] Scenario 1: Daily Commuting. Users may start and stop the vehicle multiple times a day. This system ensures that the fuel cell stack is properly protected after each shutdown (regardless of duration), addressing users' concerns about performance degradation after long-term use of fuel cell vehicles, and improving product reliability and user confidence.

[0075] Scenario 2: Emergency Situation. In emergency situations such as collisions, the vehicle safety system will issue an emergency stop command. The system of this invention can be linked with the vehicle's overall safety system to immediately activate the shutdown degradation suppression program while cutting off the main fuel supply, preventing secondary safety risks or irreversible damage caused by the high temperature of the fuel cell stack exposed to air after an accident.

[0076] Example 4: Rail transit vehicles (such as locomotives and trams): These vehicles have extremely high requirements for system reliability and lifespan. When trains enter stations, return to the depot at night, or are undergoing line maintenance, the shutdown protection system of this invention can ensure that the core stack of large fuel cell power units is not affected by degradation under various planned or unplanned shutdown conditions, thus guaranteeing the punctuality rate and long-term operating costs of public transportation.

[0077] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A shutdown degradation suppression system for a solid oxide fuel cell system, characterized in that, include: Fuel cell module, protective gas supply module, and electronic control unit; The protective gas supply module includes a gas source, a pressure reducing device, a manual valve, a first isolation valve, and a mass flow controller connected in sequence. The output of the mass flow controller is connected to the heat exchange component of the fuel cell module, and the heat exchange component is connected to the anode of the fuel cell module. The anode outlet of the fuel cell module is connected in sequence to a condenser and a second isolation valve. The electronic control unit is electrically connected to the mass flow controller, the first isolation valve, and the second isolation valve. The electronic control unit is configured to control the first isolation valve and the second isolation valve to close after the system shutdown command is triggered, so that the anode gas path of the fuel cell module forms a closed cavity, and to perform pressure holding control of the closed cavity.

2. The shutdown degradation suppression system for a solid oxide fuel cell system as described in claim 1, characterized in that, Perform pressure control on the sealed cavity, including: Real-time pressure monitoring of the sealed cavity; If the pressure is greater than or equal to the preset upper limit threshold, the second isolation valve will be opened to release the pressure. If the pressure is less than the preset upper limit threshold and the pressure is less than or equal to the preset lower limit threshold, the first isolation valve is opened, and a certain amount of hydrogen-nitrogen mixed protective gas is introduced into the sealed cavity through the mass flow controller until the pressure reaches the preset upper limit threshold and then the first isolation valve is closed. If the pressure is less than the preset upper limit threshold and greater than the preset lower limit threshold, the stack temperature of the fuel cell module is acquired in real time while pressure holding control is performed. When the stack temperature is lower than the preset minimum decay limit, pressure holding control is stopped; otherwise, pressure holding control continues.

3. The shutdown degradation suppression system for a solid oxide fuel cell system as described in claim 1, characterized in that, A first pressure sensor is installed on the connecting pipeline between the gas source and the pressure reducing device, and a second pressure sensor is installed on the pipeline between the heat exchange component and the anode. Both the first and second pressure sensors are connected to the electronic control unit.

4. The shutdown degradation suppression system for a solid oxide fuel cell system as described in claim 1, characterized in that, A temperature sensor is installed between the anode and the condenser of the fuel cell. The temperature sensor is connected to the electronic control unit. The pressure reducing device is configured to reduce the pressure of the high-pressure hydrogen-nitrogen mixture from the gas source to a safe pressure suitable for the fuel cell module's gas circuit. The manual valve is a manual shut-off valve used to physically isolate the protective gas supply to the module during system maintenance.

5. A method for suppressing shutdown degradation in a solid oxide fuel cell system, characterized in that, The process includes the following: In response to a system shutdown command, the first isolation valve and the second isolation valve are closed to form a sealed cavity; Real-time pressure monitoring of the sealed cavity; If the pressure is greater than or equal to the preset upper limit threshold, the second isolation valve will be opened to release the pressure. If the pressure is less than the preset upper limit threshold and the pressure is less than or equal to the preset lower limit threshold, the first isolation valve is opened, and a certain amount of hydrogen-nitrogen mixed protective gas is introduced into the sealed cavity through the mass flow controller until the pressure reaches the preset upper limit threshold and then the first isolation valve is closed. If the pressure is less than the preset upper limit threshold and greater than the preset lower limit threshold, the stack temperature of the fuel cell module is acquired in real time while pressure holding control is performed. When the stack temperature is lower than the preset minimum decay limit, pressure holding control is stopped; otherwise, pressure holding control continues.

6. The method for suppressing shutdown degradation in a solid oxide fuel cell system as described in claim 5, characterized in that, Prior to responding to a system shutdown command, the procedure also includes performing a safety purging to remove residual fuel from the anode gas path of the fuel cell module.

7. The method for suppressing shutdown degradation in a solid oxide fuel cell system as described in claim 5, characterized in that, Introducing a fixed amount of hydrogen-nitrogen mixed protective gas includes: calculating the total amount of hydrogen-nitrogen mixed protective gas to be introduced based on the volume of the sealed cavity and the difference between the current pressure and the target holding pressure; accumulating the flow rate of the introduced hydrogen-nitrogen mixed protective gas through a mass flow controller, and stopping the introduction when the accumulated flow rate reaches the total amount.

8. The method for suppressing shutdown degradation in a solid oxide fuel cell system as described in claim 5, characterized in that, After the pressure holding control is stopped, the procedure also includes: controlling the second isolation valve to open slowly to smoothly release the residual pressure in the sealed cavity.

9. A solid oxide fuel cell system, characterized in that, Includes the shutdown degradation suppression system for solid oxide fuel cell systems as described in any one of claims 1-4.

10. A vehicle, characterized in that, Includes the shutdown degradation suppression system for solid oxide fuel cell systems according to any one of claims 1-4; or includes the solid oxide fuel cell system according to claim 9.

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