A method and system for controlling the uninterrupted operation of a power high temperature fuel cell system

Abstract

This invention discloses a method and system for uninterrupted operation control of a high-temperature fuel cell system, relating to the field of fuel cell technology. The method includes: detecting the open-circuit voltage of the fuel cell stack in standby or idling mode of the high-temperature fuel cell, and comparing the open-circuit voltage with a set voltage threshold; wherein the voltage threshold is between the normal operating open-circuit voltage and the critical open-circuit voltage of the fuel cell stack; if the open-circuit voltage is not greater than the set voltage threshold, then implementing set oxygen leakage consumption measures to control the oxygen partial pressure on the hydrogen electrode side, thereby keeping the high-temperature fuel cell in standby or idling mode. This allows the fuel cell stack to be maintained in high-temperature standby and idling mode, minimizing frequent start-ups and shutdowns of the fuel cell stack and solving the time-sensitivity and degradation problems caused by fuel cell stack start-ups and shutdowns.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method and system for uninterrupted operation control of a power-type high-temperature 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] Existing high-temperature fuel cells, such as solid oxide fuel cells and molten carbonate fuel cells, typically operate at temperatures of 500-1000℃. In standby or idling conditions, if the fuel cell stack is directly kept at high temperatures, a continuous supply of reducing fuel gas is required, increasing standby costs and safety hazards. Furthermore, when the fuel supply system is shut down, the nickel-based material on the hydrogen electrode side is easily oxidized to nickel oxide, resulting in approximately 70% volume expansion. This can easily cause the hydrogen electrode and electrolyte interface to detach, leading to a decline in battery performance.

[0004] Therefore, during standby, the fuel cell stack needs to be cooled to near room temperature to suppress nickel oxidation. Consequently, the high operating temperature of high-temperature fuel cells leads to excessively long start-stop times, limiting their application in scenarios requiring time-sensitive power sources. Furthermore, the frequent start-stop cycles exacerbate thermal-stress mismatch and other problems, causing rapid performance degradation of the fuel cell stack.

[0005] Furthermore, since the oxidation rate of nickel is related to temperature and ambient oxygen partial pressure, and there is a possibility of leakage in the battery structure, stack structure, and various seals, batteries often have a certain leakage rate, which leads to an increase in oxygen partial pressure and causes nickel oxidation.

[0006] Currently, most protection schemes for high-temperature fuel cells are often crude open-loop controls, which only consider how to protect nickel from oxidation, but cannot determine the triggering time of protection actions or detect the impact of protection actions. This results in the system being in a black box state, which requires excessive protection actions to ensure effective protection of the battery electrodes, thus wasting resources. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a method and system for uninterrupted operation control of a power-type high-temperature fuel cell system. This method enables the fuel cell stack to remain in a high-temperature standby and idling state, minimizing frequent start-ups and shutdowns of the fuel cell stack and resolving the time-sensitivity and degradation issues caused by start-ups and shutdowns of the fuel cell stack.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for uninterrupted operation control of a power-type high-temperature fuel cell system, comprising: In the standby or idling state of a high-temperature fuel cell, the open-circuit voltage of the fuel cell stack is detected and compared with a set voltage threshold; wherein, the set voltage threshold is between the normal operating open-circuit voltage and the critical open-circuit voltage of the fuel cell stack. If the open-circuit voltage is not greater than the set voltage threshold, the set oxygen consumption leakage measures are taken to control the oxygen partial pressure on the hydrogen electrode side, so that the high-temperature fuel cell is kept in standby or idling state.

[0009] As an alternative implementation, when the oxygen partial pressure on the oxygen electrode side is known, the open-circuit voltage is inversely proportional to the oxygen partial pressure on the hydrogen electrode side. Before the open-circuit voltage drops to the critical open-circuit voltage, the oxygen partial pressure on the hydrogen electrode side is insufficient to oxidize the nickel.

[0010] As an alternative implementation method, the measures for reducing oxygen leakage include: A sacrificial agent is introduced into the inner side of the fuel manifold to consume leaked oxygen from the fuel supply, wherein the oxidation priority of the sacrificial agent material is not lower than that of nickel; Alternatively, a reducing or inert gas can be introduced into the fuel manifold to consume the leaked oxygen on the hydrogen electrode side. Alternatively, a sacrificial agent can be introduced into the inside of the fuel manifold, and a reducing or inert gas can be introduced, while controlling the partial pressure of oxygen in the environment at the oxygen electrode and throughout the fuel cell stack.

[0011] As an alternative implementation method, the proposed measures for reducing oxygen leakage include: applying an external power source to the input terminal of the oxygen electrode and the output terminal of the hydrogen electrode to maintain the potential difference between the oxygen electrode and the hydrogen electrode within a safe open-circuit voltage range; under the action of the external power source, the leaked oxygen is carried back to the oxygen electrode in the form of an oxygen-permeable membrane driven by electrochemical processes.

[0012] As an alternative implementation method, the measures to prevent oxygen loss include: applying an external power source to the oxygen electrode input and hydrogen electrode output to maintain the voltage of the high-temperature fuel cell above the open-circuit voltage, and reversing the fuel cell mode to the electrolysis cell mode to maintain the oxygen partial pressure environment of the hydrogen electrode.

[0013] In a second aspect, the present invention provides a power-type high-temperature fuel cell system, including a control unit, a fuel cell stack, a protective gas unit and a power electronic system connected to the control unit, and a fuel supply unit and an air supply unit connected to the fuel cell stack. The power electronic system is connected to the fuel cell stack; The protective gas unit is connected to the fuel cell stack via a fuel supply unit and an air supply unit, or directly to the fuel cell stack. The control unit is configured to: detect the open-circuit voltage of the fuel cell stack in the standby or idling state of the high-temperature fuel cell, and compare it with a set voltage threshold. When the open-circuit voltage is not greater than the set voltage threshold, control the operation of the power electronic system or the protective gas unit to execute the set oxygen consumption leakage measures, control the oxygen partial pressure on the hydrogen electrode side, and keep the high-temperature fuel cell in the standby or idling state.

[0014] As an alternative implementation, the protective gas unit is a nitrogen supply unit, which is connected to the fuel supply unit and the air supply unit. In the standby or idling state of the high-temperature fuel cell, the fuel supply unit and the air supply unit stop. When the open circuit voltage is less than or equal to the set voltage threshold, the control unit controls the nitrogen supply unit to purge nitrogen to the fuel cell stack through the fuel supply unit and / or the air supply unit.

[0015] As an alternative implementation, the protective gas unit is a hydrogen storage unit, which is directly connected to the fuel cell stack; In the standby or idling state of the high-temperature fuel cell, the fuel supply unit and air supply unit stop. When the open circuit voltage is less than or equal to the set voltage threshold, the control unit controls the hydrogen storage unit to directly supply hydrogen to the hydrogen electrode side of the fuel cell stack to consume the leaked oxygen.

[0016] As an alternative implementation, the control unit controls the power electronic system to apply a protective voltage to the fuel cell stack to ensure that the open-circuit voltage of the fuel cell stack is always greater than a set voltage threshold. Alternatively, the control unit controls the power electronic system to apply an external voltage greater than the open-circuit voltage to the fuel cell stack and introduces water vapor, so that the fuel cell stack operates in the reverse operation mode of the electrolyzer.

[0017] As an alternative implementation, a sacrificial agent manufacturing unit is provided in the fuel inlet and fuel outlet of the fuel cell stack to absorb leaked oxygen from the fuel supply unit through a sacrificial agent.

[0018] Thirdly, the present invention provides a vehicle including the power-type high-temperature fuel cell system described in the second aspect.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: Most current protection schemes for high-temperature fuel cells only consider how to protect nickel from oxidation, without determining the triggering timing of protection actions or detecting the impact of these actions; that is, they are merely open-loop control. This invention proposes a closed-loop dynamic control strategy. By dynamically monitoring the open-circuit voltage of the fuel cell stack and taking proactive measures to reduce oxygen leakage, it controls the oxygen partial pressure on the hydrogen electrode side. This allows the high-temperature fuel cell to maintain its operation in high-temperature standby and idling states for extended periods, enabling rapid startup when needed. This minimizes power consumption and degradation of the fuel cell stack in high-temperature standby and idling states, solving the key and common technical challenges of slow start-up and shutdown and degradation after multiple thermal cycles in power-type high-temperature fuel cell stacks, thus meeting the demand for time-efficient and long-life power sources in various scenarios.

[0020] 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

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a short stack consisting of two batteries provided in Embodiment 1 of the present invention; Figure 2 This is a graph showing the change of open-circuit voltage over time after the battery fuel supply is cut off, as provided in Embodiment 1 of the present invention. Figure 3 This is a flowchart of the uninterrupted operation control method for a power-type high-temperature fuel cell system provided in Embodiment 1 of the present invention; Figure 4 This is a comparison chart of the operating effects of the power-type high-temperature fuel cell system provided in Embodiment 1 of the present invention; Figure 5 This is a structural diagram of a high-temperature fuel cell system with nitrogen purging provided in Embodiment 2 of the present invention; Figure 6 This is a structural diagram of a high-temperature fuel cell system with a hydrogen storage unit provided in Embodiment 2 of the present invention; The components are: 1. Oxygen electrode; 2. Hydrogen electrode; 3. Electrolyte; 4. Connector; 5. Sacrificial agent; 6. Fuel cell stack; 7. Control unit; 8. Power module; 9. Power electronic system; 10. Fuel supply unit; 11. Air supply unit; 12. Nitrogen supply unit; and 13. Hydrogen storage unit. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] 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.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0027] Terminology explanation.

[0028] Idle state: The fuel cell maintains the minimum stable state of operation at zero or low power, only maintaining its own operation, but has no power output to the outside (net output power ≈ 0), only supplying the fuel and oxidant required to maintain the reaction, and maintaining high temperature operation.

[0029] Partial pressure: If all other gases except a certain gas are removed from a gas mixture while keeping the system volume and temperature constant, the pressure of the gas at this time is called the partial pressure of that gas in the gas mixture.

[0030] Oxygen partial pressure: The partial pressure of oxygen in a gas mixture.

[0031] Hydrogen electrode: The electrode in a fuel cell where hydrogen reacts or produces hydrogen.

[0032] Open-loop control: A control method that does not receive feedback information from the controlled object.

[0033] Example 1 In the actual operation of most high-temperature fuel cell stacks, if the fuel cell stack is directly kept at high temperatures (500-1000℃), a continuous supply of reducing fuel gas is required, which increases standby costs and safety hazards. Furthermore, when the fuel supply system is shut down, the nickel-based material on the hydrogen electrode side is easily oxidized to nickel oxide, resulting in approximately 70% volume expansion. This can significantly cause the hydrogen electrode and electrolyte interface to detach, leading to a decline in battery performance. Therefore, when the fuel cell stack is in standby mode, it is necessary to cool it to near room temperature to suppress nickel oxidation.

[0034] Since the oxidation rate of nickel is directly related to the operating temperature and the partial pressure of oxygen in the environment, the oxidation of nickel can be avoided by reducing the partial pressure of oxygen in the environment on the hydrogen electrode side to below the critical oxygen partial pressure at that temperature without lowering the operating temperature.

[0035] Ideally, even after the fuel cell is shut down, the residual reducing fuel gas on the hydrogen electrode side is sufficient to maintain the hydrogen electrode side at an extremely low oxygen partial pressure.

[0036] However, in actual operation, due to the possibility of leakage in the battery structure, stack structure, and various seals, the battery often has a certain leakage rate, which leads to an increase in oxygen partial pressure.

[0037] Based on the Elingham diagram (oxygen potential diagram) or thermodynamic calculations, nickel can be obtained at 600... o The critical oxygen partial pressure at C is approximately 10. -14 Pa, while the open-circuit voltage of the hydrogen electrode side during normal operation of the fuel cell can be estimated to be approximately 10 Pa. -23 Pa. Therefore, the oxygen partial pressure on the hydrogen electrode side can change dramatically even with a small amount of oxygen leakage (10 Pa). -14 Pa and 10 -23 Pa is a very small quantity.

[0038] like Figure 1 As shown, taking a short stack consisting of two batteries as an example, the two batteries are connected by connector 4 to form a short stack. The oxygen leakage mainly includes cross leakage from fuel supply and cross leakage from oxygen electrode 1.

[0039] Specifically: (1) Cross-leakage from fuel supply. After the fuel supply is shut down, oxygen may leak from the reformer of the fuel supply system, the fuel manifold and the incomplete seal between the hydrogen electrode 2 and the connector 4, and then diffuse to the interface of the hydrogen electrode 2-electrolyte 3.

[0040] (2) Cross-leakage from oxygen electrode 1. Since electrolyte 3 is not dense or has both electronic and ionic conductivity, oxygen will diffuse directly from oxygen electrode 1 to the interface of hydrogen electrode 2-electrolyte 3 in a physical or electrochemical manner due to the concentration difference between the two electrodes. This may cause oxidation of nickel at the interface of hydrogen electrode 2-electrolyte 3, which will then damage the battery.

[0041] Therefore, it is necessary to cut off or neutralize the two types of oxygen leakage to prevent the local oxygen partial pressure from increasing to above the critical oxygen partial pressure.

[0042] The challenge of this solution lies in how to dynamically detect a minimum oxygen partial pressure, a feature not addressed in most fuel cell system protection schemes. Existing solutions often employ open-loop control, meaning they cannot detect the impact of protection actions. This embodiment proposes a dynamic detection and control technology for initiating protection actions, thereby reducing the cost of performing protection actions, such as consuming less reducing gas.

[0043] The specific plan is explained as follows: Treating the fuel cell as a concentration cell of oxygen, according to the Nernst equation, the open-circuit voltage across the fuel cell stack is described as follows: (1); In the formula, is the total open-circuit voltage of the fuel cell stack (V); n is the number of fuel cell stacks connected in series within the fuel cell stack (units). The gas constant is 8.3145 J kg. -1 K -1 ; T Where is the stack temperature in K; F is the Faraday constant in 96485.309 C mol. -1 ; The oxygen partial pressure on the oxygen electrode side is expressed in Pa. The oxygen partial pressure on the hydrogen electrode side is given in Pa.

[0044] If the oxygen partial pressure on the oxygen electrode side is known, for example, if oxygen electrode 1 is directly connected to air, its oxygen partial pressure is 81000 Pa. Then, the oxygen partial pressure on the hydrogen electrode side can be directly obtained by measuring the open-circuit voltage of the fuel cell stack. That is, as the oxygen partial pressure on the hydrogen electrode side increases, the open-circuit voltage gradually decreases. When the oxygen partial pressure on the hydrogen electrode side increases to the critical oxygen partial pressure, the open-circuit voltage of the fuel cell stack also decreases accordingly to the critical open-circuit voltage.

[0045] like Figure 2 The graph shows the change of open-circuit voltage over time between terminal A of oxygen electrode 1 and terminal B of hydrogen electrode 2 after the battery fuel supply is cut off. The red line represents the set voltage threshold, and the dashed line represents the actual voltage measured during the process.

[0046] Clearly, the oxygen partial pressure on the hydrogen electrode side is low enough to prevent nickel oxidation before the open-circuit voltage drops to the critical open-circuit voltage.

[0047] Assuming the oxygen electrode side is always open to the atmosphere, the value of a short stack consisting of two cells connected in series at 600°C can be calculated using equation (1). o The safe open-circuit voltage range under C is 1.6-2.4 V.

[0048] Therefore, the oxygen partial pressure on the hydrogen electrode side can be obtained by real-time monitoring of the open-circuit voltage of the cell or stack. This embodiment utilizes the open-circuit voltage to monitor the oxygen partial pressure on the hydrogen electrode side, and then uses this variable as an input to control the fuel cell system. As long as active measures are taken to reduce the oxygen partial pressure on the hydrogen electrode side before the open-circuit voltage drops to a critical open-circuit voltage, the problem can be solved.

[0049] The specific execution process is as follows: Figure 3 As shown, it includes: In the standby or idling state of a high-temperature fuel cell, the open-circuit voltage of the fuel cell stack is detected and compared with a set voltage threshold; wherein, the set voltage is between the normal operating open-circuit voltage and the critical open-circuit voltage of the fuel cell stack. If the open-circuit voltage is greater than the set voltage threshold, the high-temperature fuel cell system will be started upon receiving a start command; otherwise, the open-circuit voltage will be continuously monitored. If the open-circuit voltage is not greater than the set voltage threshold, the set oxygen consumption leakage measures are taken to control the oxygen partial pressure on the hydrogen electrode side, so that the high-temperature fuel cell is kept in standby or idling state. Thus, the high-temperature fuel cell can be started quickly when it needs to be started.

[0050] In this embodiment, active measures refer to a variety of actions that can effectively reduce the oxygen partial pressure on the hydrogen electrode side, including but not limited to one or a combination of the following methods.

[0051] Specifically: 1. In the fuel manifold ( Figure 1 Cells made of sacrificial agent 5, such as particles or films, are introduced into the inner side of the fuel inlet manifold to consume leaked oxygen from the fuel supply system, ensuring that nickel in the electrodes is not preferentially oxidized. When the actual fuel cell is operating normally, the reducing gas introduced into the fuel manifold can reduce the oxides of these materials back to elemental form, ensuring the recycling of sacrificial agent 5. The oxidation priority of sacrificial agent 5 materials is no less than that of nickel, and includes, but is not limited to, Ni, Co, Fe, Sn, C, Cr, V, Mn, Ti, Al, Mg, etc.

[0052] 2. Based on the leakage rate of the fuel cell stack test, in the fuel manifold ( Figure 1Slowly introduce reducing or inert gases, including but not limited to CO, H2, N2, Ar, etc., into the fuel inlet and fuel outlet of the hydrogen electrode to consume or remove the leaked oxygen on both sides of the hydrogen electrode.

[0053] 3. By adopting strategies 1 and 2 above, the oxygen partial pressure in the environment of the oxygen electrode 1 side and the entire fuel cell stack system is controlled, and the oxygen partial pressure in the environment of the oxygen electrode 1 side and the entire fuel cell stack system is significantly reduced, so as to reduce the oxygen content in the leaked gas to the hydrogen electrode 2 side.

[0054] 4. Use an external power source (such as a battery) to act on Figure 1 Between terminals A and B, the potential difference between oxygen electrode 1 and hydrogen electrode 2 is maintained within a safe open-circuit voltage range (1.6-2.4 V). (If strategy 3 is adopted, it needs to be recalculated based on the actual oxygen partial pressure on the oxygen electrode side.) Once oxygen leakage occurs, under the action of an external power supply, the leaked oxygen will be carried back to oxygen electrode 1 in the form of an oxygen-permeable membrane driven by electrochemical power.

[0055] 5. Use an external power source (such as a battery) to act on Figure 1 Between terminals A and B, the voltage of the fuel cell system is maintained above the open-circuit voltage, directly reversing the fuel cell mode to electrolyzer mode to produce hydrogen by electrolyzing water vapor, thus maintaining the low oxygen partial pressure environment of hydrogen electrode 2. The electrolyzed hydrogen can be stored in the hydrogen storage unit inside the fuel cell system as backup fuel or as a source of reducing gas in Strategy 2, or it can be supplied to another operating fuel cell system or stored in an external hydrogen storage container.

[0056] This embodiment proposes an uninterrupted operation control method for a power-type high-temperature fuel cell system. By dynamically monitoring the open-circuit voltage at both ends of the battery, the oxygen partial pressure on the hydrogen electrode side is controlled, enabling the high-temperature fuel cell to maintain a high-temperature standby and idling state for a long time, and allowing the high-temperature fuel cell stack to start up quickly when needed.

[0057] like Figure 4 As shown, where, Figure 4 (a) in the figure is a diagram showing the effect of using the control method of this embodiment. Figure 4 (b) in the figure shows the effect when starting from room temperature. It can be seen that when the strategy of this embodiment is not implemented, the system needs to start from room temperature, and the battery startup time needs to go through an additional delay before it can output full power. This puts forward higher requirements on the capacity of the vehicle battery. Frequent thermal cycling also causes the battery to fail due to frequent hot and cold cycles, making it difficult for high-temperature fuel cells to be applied to the use-and-go scenario for a long time.

[0058] When the strategy of this embodiment is adopted, after the power-type high-temperature fuel cell stack is shut down, the power-type high-temperature fuel cell stack is maintained at a high temperature. When the power-type high-temperature fuel cell stack requires power output, it can quickly reach the rated working state, reducing the capacity requirements of the vehicle battery. This meets the requirements of rapid start-up and shutdown in vehicle scenarios and solves the common technical problems of slow start-up and shutdown and degradation after multiple thermal cycles of the power-type high-temperature fuel cell stack.

[0059] Example 2 Based on the uninterrupted operation control method of the power-type high-temperature fuel cell system described in Example 1, this example proposes a power-type high-temperature fuel cell system, including: a control unit 7, a fuel cell stack 6, a protective gas unit and a power electronic system 9 connected to the control unit 7, and a fuel supply unit 10 and an air supply unit 11 connected to the fuel cell stack 6. Among them, the fuel supply unit 10 is connected to the fuel inlet of the fuel cell stack 6, and the air supply unit 11 is connected to the air inlet of the fuel cell stack 6. The power electronics system 9 is connected to the fuel cell stack 6; The protective gas unit is connected to the fuel cell stack 6 via the fuel supply unit 10 and the air supply unit 11, or directly to the fuel cell stack 6. The control unit 7 is configured to: detect the open-circuit voltage of the fuel cell stack 6 in the standby or idling state of the high-temperature fuel cell, and compare it with a set voltage threshold. When the open-circuit voltage is not greater than the set voltage threshold, control the power electronic system 9 or the protective gas unit to perform the set oxygen consumption leakage measures, control the oxygen partial pressure on the hydrogen electrode side, and keep the high-temperature fuel cell in the standby or idling state.

[0060] In this embodiment, the fuel cell stack 6 is composed of several fuel cell cells connected in series and / or in parallel via a connector 4. It is mainly used to provide electrical power output. The fuel cells can be solid oxide fuel cells, molten carbonate fuel cells, or other high-temperature fuel cells.

[0061] The fuel cell stack 6 also includes a fuel inlet, a fuel outlet, an air inlet, and an air outlet for supplying and discharging fuel and gas for the stack.

[0062] In this embodiment, the power electronic system 9 is connected to the power module 8 (such as a battery). The power module 8 is mainly responsible for storing or outputting electrical energy and can be a lithium battery, lead-acid battery or other storage battery, supercapacitor or similar energy storage device.

[0063] In this embodiment, the power electronic system 9 mainly performs operations such as step-up / step-down, step-down / step-up, DC / AC conversion, and positive / negative polarity conversion on the input / output current and voltage between the fuel cell stack 6 and the power module 8 to meet the requirements of multi-strategy operation.

[0064] In this embodiment, the control unit 7 collects real-time data such as flow rate, temperature, pressure, voltage, current and capacity of the fuel cell stack 6, power module 8, power electronic system 9, fuel supply unit 10, air supply unit 11 and protective gas unit through sensors, and directly controls the power electronic system 9, fuel supply unit 10, air supply unit 11 and protective gas unit based on this data.

[0065] In this embodiment, the fuel supply unit 10 controls parameters such as the gas intake flow rate, pressure, and temperature to provide the required gas for the fuel cell stack 6.

[0066] In this embodiment, the air supply unit 11 controls parameters such as airflow, pressure, and temperature entering the fuel cell stack module to provide the required air for the fuel cell stack 6.

[0067] In this embodiment, the protective gas unit controls the corresponding gas intake flow rate, pressure, temperature and other parameters, and is connected to the fuel supply unit 10 and the air supply unit 11 to provide protective gas for the fuel cell stack 6, or is directly connected to the fuel cell stack 6 to provide protective gas for the fuel cell stack 6.

[0068] The protective gas unit can be a nitrogen supply unit 12, a hydrogen storage unit 13, or other inert or reducing gas devices with basic storage and supply functions.

[0069] like Figure 5 As shown, the protective gas unit adopts a nitrogen supply unit 12, providing a power-type high-temperature fuel cell system with nitrogen purging, wherein the nitrogen supply unit 12 is connected to the fuel supply unit 10 and the air supply unit 11.

[0070] When the fuel cell system is operating normally, the nitrogen supply unit 12 is turned off, and the fuel supply unit 10 and air supply unit 11 supply fuel and gas to the fuel cell stack 6. The DC power output by the fuel cell stack 6 is supplied by... Figure 5 Terminals C and D in the circuit are led out and pass through terminals E and F of the power electronic system 9 to charge the power module 8 or output electrical energy.

[0071] When the fuel cell system shuts down, the fuel supply unit 10 and the air supply unit 11 stop, and the control unit 7 monitors the open-circuit voltage of the fuel cell stack 6 in real time. When the open-circuit voltage is less than or equal to the set voltage threshold, the control unit 7 controls the nitrogen supply unit 12 to purge nitrogen into the fuel cell stack 6 through the fuel supply unit 10 and / or the air supply unit 11 to consume leaked oxygen and control the oxygen partial pressure on the hydrogen electrode side.

[0072] As an alternative, the control unit 7 controls the power electronic system 9 to apply a protective voltage to the terminals C and D of the fuel cell stack 6 through terminals E and F of the power electronic system 9, so as to ensure that the open circuit voltage of the fuel cell stack 6 is always greater than the set voltage threshold.

[0073] As an alternative, a sacrificial agent manufacturing unit is provided in the fuel inlet and fuel outlet of the fuel cell stack 6 to absorb the leaked oxygen from the fuel supply unit 10 through the sacrificial agent 5.

[0074] like Figure 6 As shown, the protective gas unit adopts a hydrogen storage unit 13, providing a power-type high-temperature fuel cell system with a hydrogen storage unit, wherein the hydrogen storage unit 13 is directly connected to the fuel cell stack 6.

[0075] When the fuel cell system is operating normally, the hydrogen storage unit 13 is turned off, and the fuel supply unit 10 and the air supply unit 11 supply fuel and working gas to the fuel cell stack 6. The DC power output by the fuel cell stack 6 is supplied by... Figure 6 Terminals C and D in the circuit are led out and pass through terminals E and F of the power electronic system 9 to charge the power module 8 or output electrical energy.

[0076] When the fuel cell system shuts down, the fuel supply unit 10 and the air supply unit 11 stop. The control unit 7 monitors the open circuit voltage of the fuel cell stack in real time. When the open circuit voltage is less than or equal to the set voltage threshold, the control unit 7 controls the hydrogen storage unit 13 to slowly introduce an appropriate flow of hydrogen directly into the hydrogen electrode side of the fuel cell stack 6. This can also be a reducing gas, such as CO, to consume the leaked oxygen and control the oxygen partial pressure on the hydrogen electrode side.

[0077] As an alternative, the control unit 7 controls the power electronic system 9 to apply a protective voltage to the terminals C and D of the fuel cell stack 6 through terminals E and F of the power electronic system 9, so as to ensure that the open circuit voltage of the fuel cell stack 6 is always greater than the set voltage threshold.

[0078] As an alternative, the control unit 7 controls the power electronic system 9 to apply an external voltage greater than the open-circuit voltage to the terminals C and D of the fuel cell stack 6 through the terminals E and F of the power electronic system 9, and introduces water vapor so that the fuel cell stack 6 operates in the reverse operation mode of the fuel cell electrolyzer. The hydrogen produced by electrolysis can be stored in the hydrogen storage unit 13 or introduced to the outside.

[0079] As an alternative, a sacrificial agent manufacturing unit is provided in the fuel inlet and fuel outlet of the fuel cell stack 6 to absorb the leaked oxygen from the fuel supply unit 10 through the sacrificial agent 5.

[0080] Example 3 This embodiment provides a vehicle including the power-type high-temperature fuel cell system described in Embodiment 2.

[0081] Understandably, the core of this invention lies in proposing a method for uninterrupted operation control of a power-type high-temperature fuel cell system. By dynamically monitoring the open-circuit voltage of the fuel cell stack, the oxygen partial pressure on the hydrogen electrode side is controlled, enabling the high-temperature fuel cell to maintain a high-temperature standby and idling state for a long time. This allows the high-temperature fuel cell stack to start up quickly when needed, solving the key and common technical problems of slow start-up and shutdown and degradation after multiple thermal cycles in power-type high-temperature fuel cell stacks. This is beneficial to extending the lifespan of high-temperature fuel cell stacks and promoting their practical application.

[0082] Therefore, based on the uninterrupted operation control method for a power-type high-temperature fuel cell system, the above embodiments provide several structures for such systems. Although specific embodiments of the present invention have been described in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solution of this invention, simple modifications and arrangements of the above structure are easily achievable by those skilled in the art, and various modifications or variations that can be made by those skilled in the art without creative effort are still within the protection scope of this invention. The various embodiments of this invention are interconnected, but each embodiment has a different focus. Similar parts between embodiments can be referred to mutually.

[0083] The basic principles of the present invention can be implemented in other embodiments with slight modifications. Therefore, the scope of the present invention is not limited to the embodiments shown herein, but is within the broadest range that conforms to the principles and novel features disclosed herein.

Claims

1. A method for uninterrupted operation control of a power-type high-temperature fuel cell system, characterized in that, include: In the standby or idling state of a high-temperature fuel cell, the open-circuit voltage of the fuel cell stack is detected and compared with a set voltage threshold; wherein, the set voltage threshold is between the normal operating open-circuit voltage and the critical open-circuit voltage of the fuel cell stack. If the open-circuit voltage is not greater than the set voltage threshold, the set oxygen consumption leakage measures are taken to control the oxygen partial pressure on the hydrogen electrode side, so that the high-temperature fuel cell is kept in standby or idling state.

2. The uninterrupted operation control method for a power-type high-temperature fuel cell system as described in claim 1, characterized in that, When the oxygen partial pressure on the oxygen electrode side is known, the open-circuit voltage is inversely proportional to the oxygen partial pressure on the hydrogen electrode side. Before the open-circuit voltage drops to the critical open-circuit voltage, the oxygen partial pressure on the hydrogen electrode side is insufficient to oxidize nickel.

3. The uninterrupted operation control method for a power-type high-temperature fuel cell system as described in claim 1, characterized in that, The measures to address oxygen leakage include: A sacrificial agent is introduced into the inner side of the fuel manifold to consume leaked oxygen from the fuel supply, wherein the oxidation priority of the sacrificial agent material is not lower than that of nickel; Alternatively, a reducing or inert gas can be introduced into the fuel manifold to consume the leaked oxygen on the hydrogen electrode side. Alternatively, a sacrificial agent can be introduced into the inside of the fuel manifold, and a reducing or inert gas can be introduced, while controlling the partial pressure of oxygen in the environment at the oxygen electrode and throughout the fuel cell stack.

4. The uninterrupted operation control method for a power-type high-temperature fuel cell system as described in claim 1, characterized in that, The proposed measures to consume leaked oxygen include: applying an external power source to the input and output terminals of the oxygen and hydrogen electrodes to maintain the potential difference between them within a safe open-circuit voltage range; and, under the action of the external power source, the leaked oxygen is carried back to the oxygen electrode in the form of an oxygen-permeable membrane driven by electrochemical processes.

5. The uninterrupted operation control method for a power-type high-temperature fuel cell system as described in claim 1, characterized in that, The measures to address oxygen consumption leakage include: applying an external power source to the oxygen electrode input and hydrogen electrode output to maintain the voltage of the high-temperature fuel cell above the open-circuit voltage; and reversing the fuel cell mode to the electrolysis cell mode to maintain the oxygen partial pressure environment of the hydrogen electrode.

6. A power-type high-temperature fuel cell system, comprising a control unit, a fuel cell stack, a protective gas unit and a power electronic system connected to the control unit, and a fuel supply unit and an air supply unit connected to the fuel cell stack; The power electronic system is connected to the fuel cell stack; The protective gas unit is connected to the fuel cell stack via a fuel supply unit and an air supply unit, or directly to the fuel cell stack. The control unit is configured to: detect the open-circuit voltage of the fuel cell stack in the standby or idling state of the high-temperature fuel cell, and compare it with a set voltage threshold. When the open-circuit voltage is not greater than the set voltage threshold, control the operation of the power electronic system or the protective gas unit to execute the set oxygen consumption leakage measures, control the oxygen partial pressure on the hydrogen electrode side, and keep the high-temperature fuel cell in the standby or idling state.

7. A power-type high-temperature fuel cell system as described in claim 6, characterized in that, The protective gas unit is a nitrogen supply unit, which is connected to the fuel supply unit and the air supply unit. In the standby or idling state of the high-temperature fuel cell, the fuel supply unit and the air supply unit stop. When the open circuit voltage is less than or equal to the set voltage threshold, the control unit controls the nitrogen supply unit to purge nitrogen to the fuel cell stack through the fuel supply unit and / or the air supply unit.

8. A power-type high-temperature fuel cell system as described in claim 6, characterized in that, The protective gas unit is a hydrogen storage unit, which is directly connected to the fuel cell stack. In the standby or idling state of the high-temperature fuel cell, the fuel supply unit and air supply unit stop. When the open circuit voltage is less than or equal to the set voltage threshold, the control unit controls the hydrogen storage unit to directly supply hydrogen to the hydrogen electrode side of the fuel cell stack to consume the leaked oxygen.

9. A power-type high-temperature fuel cell system as described in claim 6, characterized in that, The control unit controls the power electronic system to apply a protective voltage to the fuel cell stack to ensure that the open-circuit voltage of the fuel cell stack is always greater than the set voltage threshold. Alternatively, the control unit controls the power electronic system to apply an external voltage greater than the open-circuit voltage to the fuel cell stack and introduces water vapor, so that the fuel cell stack operates in the reverse operation mode of the electrolyzer. Alternatively, sacrificial agent manufacturing units can be installed within the fuel inlet and fuel outlet of the fuel cell stack to absorb leaked oxygen from the fuel supply unit using sacrificial agents.

10. A vehicle, characterized in that, Including the power-type high-temperature fuel cell system as described in any one of claims 6-9.

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