A fuel cell idle voltage control method

Abstract

This invention discloses a fuel cell idle voltage control method applied to a fuel cell stack with a blind-end air bypass. The method includes: receiving an idle operation command; reducing the output power of the air compressor and the opening of the main air inlet valve of the fuel cell stack; keeping the main air outlet valve of the fuel cell stack open and the blind-end air bypass valve closed; and monitoring the voltage of the fuel cell at the inlet and blind-end terminals in real time. When the voltage of the inlet terminal cell approaches a preset upper voltage limit or the voltage of the blind-end cell approaches a preset lower voltage limit, the opening and closing states of the main air inlet / outlet valve and the blind-end air bypass valve are switched. The pressure distribution of the airflow field within the fuel cell stack is changed through the blind-end bypass pipeline, making the pressure difference between the air inlet and outlet of each cell approach uniformity. The opening of the corresponding valves is continuously adjusted to maintain the voltage of each cell within a preset range until a normal operation command is received, at which point the valves are restored to their initial normal operation state. This invention can control the idle voltage of each cell within the target range for an extended period.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for controlling the idle voltage of a fuel cell. Background Technology

[0002] As a clean and efficient electrochemical power generation device, fuel cells have been widely applied and promoted in various fields such as transportation, stationary power generation, and portable power supplies due to their advantages of zero emissions, high energy conversion efficiency, and long driving range. Idle / standby conditions are one of the most common operating conditions in fuel cell systems. Under these conditions, the system needs to maintain the stack voltage within a reasonable range to avoid degradation of the core stack materials caused by excessively high potentials, while also ensuring a rapid response when the system receives a start-up command. Therefore, the precise and stable control of the idle voltage is directly related to the operational safety, durability, and responsiveness of the fuel cell system.

[0003] Most publicly available fuel cell idle voltage control schemes focus on regulating the overall average voltage of the stack. This is primarily achieved by adjusting the air compressor output power and the opening of the intake and exhaust valves to control the total air intake of the stack, or by cutting off the air supply combined with stack self-discharge, thus keeping the average voltage within a preset reasonable range. While these schemes can achieve basic regulation of the overall stack average voltage, they cannot solve the problem of uneven voltage distribution among the individual cells within the stack. This deficiency is particularly pronounced in fuel cell stacks with air inlets and outlets arranged on the same side, which are currently widely used.

[0004] like Figure 1 As shown, for fuel cell stacks with air inlets and outlets arranged on the same side, the air inlets and outlets are concentrated on the same end plate of the stack, and the other end of the stack is a blind end structure without fluid inlets and outlets. Although this structure can improve system integration and simplify pipeline layout, it has an inherent problem of uneven flow field distribution. Under high flow rate conditions at rated power operation, the air flow inside the stack is sufficient, and the pressure difference and flow rate difference between individual cells can be ignored. However, under idling conditions, in order to control the stack voltage, the total air intake needs to be significantly reduced. At this time, the problem of uneven flow field is significantly amplified. The pressure difference and flow rate of the individual cells near the air inlet and outlet are large, while the pressure difference and flow rate of the blind end individual cells far from the inlet and outlet are small.

[0005] like Figure 2As shown, with the extension of idling operation time, the voltage of individual cells at the inlet and outlet ends of the fuel cell stack will continue to rise, while the voltage of individual cells at the blind end will decrease significantly. Even if the average voltage of the entire stack remains within the preset range, some individual cell voltages will exceed the reasonable upper limit, while others will fall below the reasonable lower limit, ultimately causing the idling voltage control strategy to completely fail. Excessively high individual cell voltages will accelerate the degradation of the fuel cell stack catalyst and the corrosion of the carbon support, while excessively low individual cell voltages will lead to undergassing of individual cells or even reverse polarity risks. This will not only significantly shorten the service life of the fuel cell stack but also pose safety hazards to the long-term stable operation of the system.

[0006] Currently, no existing technology has proposed an effective solution to this problem, and it is impossible to achieve balanced regulation of the voltage of each individual cell within the stack while controlling the average voltage of the entire stack. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a fuel cell idle voltage control method that enables the inlet and outlet pressure differences of each individual cell to be nearly identical, thereby maintaining the idle voltage of each individual cell within the target range over a long period.

[0008] The technical solution adopted in this invention is as follows: A fuel cell idle voltage control method, applied to a fuel cell stack with a blind-end air bypass, the method comprising: Upon receiving the idle speed operation command, the air compressor output power and the opening of the fuel cell air inlet main valve are reduced, the fuel cell air outlet main valve is kept open and the blind end air bypass valve is closed, and the voltage of the fuel cell inlet end and the blind end single cell are monitored in real time. When the voltage of a single cell at the air inlet is close to the preset upper limit or the voltage of a single cell at the blind end is close to the preset lower limit, the opening and closing states of the main air inlet and outlet valves and the blind end air bypass valves are switched. The pressure distribution of the air flow field in the stack is changed through the blind end bypass pipeline, so that the pressure difference between the air inlet and outlet of each single cell approaches the same. The valve opening is continuously adjusted to maintain the voltage of each cell in the fuel cell stack within the preset range until a normal operation command is received, at which point each valve is restored to its initial normal operation state.

[0009] Furthermore, the blind-end air bypass includes a blind-end exhaust bypass disposed between the blind end of the fuel cell stack and the air outlet main line, and the blind-end air bypass valve includes a blind-end exhaust valve disposed in the blind-end exhaust bypass; when switching the valve opening and closing state, the main air outlet valve of the fuel cell stack is closed and the blind-end exhaust valve is opened, so that air enters the fuel cell stack through the main air inlet valve of the fuel cell stack and is discharged from the blind-end exhaust bypass of the blind end of the fuel cell stack, thereby changing the air pressure gradient along the airflow direction in the fuel cell stack and reducing the air inlet and outlet pressure difference between the fuel cell stack air inlet end and each single cell in the blind end.

[0010] Furthermore, while maintaining the voltage of each cell in the stack within a preset range, the opening of the blind-end exhaust valve is dynamically adjusted using the real-time voltage of each cell as a feedback signal, continuously adjusting the pressure distribution of the airflow field inside the stack, so that the air inlet and outlet pressure difference of each cell in the stack remains close to the same.

[0011] Furthermore, the blind-end air bypass includes a blind-end air intake bypass located between the fuel cell stack air inlet main and the fuel cell stack blind end. The blind-end air bypass valve includes a blind-end air intake valve located in the blind-end air intake bypass. When switching the valve opening and closing state, the fuel cell stack air inlet main valve is closed and the blind-end air intake valve is opened, allowing air to enter the fuel cell stack from the blind end via the blind-end air intake bypass and then exit from the fuel cell stack air outlet main valve. This reverses the air flow direction and pressure gradient within the fuel cell stack, reduces the air inlet and outlet pressure difference between the fuel cell stack blind end and the air intake end of each cell, and balances the air flow and voltage level of each cell within the fuel cell stack.

[0012] Furthermore, while maintaining the voltage of each cell in the stack within a preset range, the opening of the blind end air inlet valve is dynamically adjusted using the real-time voltage of each cell as a feedback signal, continuously adjusting the pressure distribution of the air flow field inside the stack, so that the air inlet and outlet pressure difference of each cell in the stack remains close to the same.

[0013] Furthermore, the blind-end air bypass includes a blind-end air intake bypass and a blind-end air exhaust bypass. The blind-end air intake bypass is located between the fuel cell stack air inlet main and the fuel cell stack blind end, and the blind-end air exhaust bypass is located between the fuel cell stack blind end and the air outlet main. The blind-end air bypass valve includes a blind-end air intake valve located in the blind-end air intake bypass and a blind-end air exhaust valve located in the blind-end air exhaust bypass. When switching the valve opening and closing state, the air flow path and pressure distribution mode in the fuel cell stack are switched by the combination of opening and closing of the blind-end air intake valve and the blind-end air exhaust valve, so that the air inlet and outlet pressure difference of each cell in the fuel cell stack remains close to the same.

[0014] Furthermore, during idling operation, based on the dispersion of voltage of each cell in the fuel cell stack, idling duration or number of idling operations, the system alternates between the intake reverse flow mode with blind-end intake bypass and the exhaust reverse flow mode with blind-end exhaust bypass to continuously balance the airflow and voltage level of each cell in the fuel cell stack, thereby stabilizing the voltage of all cells within a preset range.

[0015] Furthermore, upon receiving a normal operation command, the blind-end air bypass valve is first closed, and then the main air inlet valve and the main air outlet valve of the fuel cell stack are simultaneously restored to the fully open state for normal operation. At the same time, the output power of the air compressor is increased, so that the fuel cell stack smoothly exits the idling condition and enters the normal operation state, allowing air to flow through the fuel cell stack along the preset positive path.

[0016] Furthermore, the blind-end air bypass is characterized in that it is connected to the internal flow field of the fuel cell stack through a blind-end air tube sheet provided at the blind end of the fuel cell stack, and the blind-end air tube sheet is provided at the cathode blind-end plate where the fuel cell stack originally had no fluid inlet or outlet.

[0017] Furthermore, the blind-end air tube plate is provided with through holes that communicate with the corresponding blind-end air bypass. The blind-end air tube plate and the cathode blind-end plate are independent separate structures, or they are integrated into a single structure.

[0018] The beneficial effects of this invention are as follows: 1. This invention addresses the problem of same-side inlet / outlet cell stack idling conditions by adding an air bypass structure to the blind end of the fuel cell stack, combined with a corresponding valve switching and opening adjustment control method for idling conditions. This fundamentally solves the problem of same-side inlet / outlet cell stack idling conditions by switching the airflow path within the stack through the blind-end bypass, reconstructing the air pressure gradient within the stack, and making the air inlet / outlet pressure difference of each cell in the stack nearly uniform. This effectively eliminates the flow difference between the inlet / outlet ends of the stack and the blind-end cells under low-inlet idling conditions, fundamentally suppressing the problem of increasing single-cell voltage dispersion with idling duration. Compared to existing solutions that only control the average voltage of the entire stack, this invention can maintain the average voltage of the entire stack within a reasonable range while ensuring that the voltage of each cell in the stack remains stable within a preset reasonable range. This completely avoids situations where the voltage of the inlet / outlet cells exceeds the upper limit and the voltage of the blind-end cells falls below the lower limit, ensuring the effectiveness of the idling voltage control strategy over long periods.

[0019] 2. This invention effectively avoids various degradation risks of fuel cell stacks under idling conditions by precisely and evenly controlling the voltage of each individual cell. Stable and controllable individual cell voltages prevent catalyst particle agglomeration, loss of active sites, and carbon support corrosion and oxidation caused by high-potential operation. It also eliminates under-air and reverse polarity phenomena in blind-end cells due to insufficient air supply, preventing irreversible degradation and damage to the membrane electrode assembly (MEA). This significantly reduces wear on core components of the stack under idling conditions, effectively extending the overall service life of the fuel cell stack and improving performance stability and consistency throughout its entire lifecycle.

[0020] 3. This invention possesses strong advantages in engineering application and scenario adaptability. It requires no structural modifications or redesigns to core functional components within the fuel cell stack, such as bipolar plates and membrane electrode assemblies. System upgrades are achieved simply by adding suitable air plates, bypass lines, and valves to the existing blind-end locations of the stack. The upgrade is cost-effective and easy to implement, suitable for both newly developed fuel cell stack systems and convenient upgrades to existing same-side inlet / outlet stack systems. Furthermore, the control logic of this invention is simple and reliable, requiring only valve opening / closing switching and closed-loop adjustment of the valve opening. No additional complex control hardware or detection devices are needed, making it directly compatible with existing fuel cell system controller architectures and facilitating large-scale deployment and application.

[0021] 4. This invention provides multiple flexible implementation schemes, allowing for selection of single-blind-end exhaust bypass, single-blind-end intake bypass, or dual-bypass combination control schemes based on different fuel cell stack structural parameters, application scenarios, and operating conditions. It offers strong adaptability. The dual-bypass combination scheme enables alternating switching between two reverse flow modes, further suppressing the voltage dispersion trend of a single cell under prolonged idling conditions and improving the long-term stability of idling control. Simultaneously, the multi-bypass structure creates control redundancy, effectively enhancing the reliability and safety of system operation. This invention is widely adaptable to the idling / standby operating conditions of various fuel cell applications, including vehicle power, stationary power generation, and backup power, possessing high practical value and promising prospects for widespread adoption. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure and air flow path of a fuel cell stack with the air inlet and outlet arranged on the same side in the existing technology.

[0023] Figure 2 This is a voltage distribution curve of each cell in the fuel cell stack under idling conditions in existing technologies.

[0024] Figure 3 This is a comparison diagram of the inlet and outlet air pressure distribution of each cell in the fuel cell stack under idling conditions according to the present invention.

[0025] Figure 4 This is a schematic diagram of the single blind-end exhaust bypass fuel cell system of the present invention.

[0026] Figure 5 This is a schematic diagram of the single blind-end intake bypass fuel cell system of the present invention.

[0027] Figure 6 This is a schematic diagram of the blind-end intake and exhaust dual bypass fuel cell system of the present invention.

[0028] Figure 7 This is a schematic diagram of the structure of the blind-end air tube sheet of the present invention. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] Example 1 This embodiment provides a fuel cell idle voltage control method, applied to a fuel cell stack with a blind-end air bypass, the method comprising: Upon receiving the idle speed operation command, the air compressor output power and the opening of the fuel cell air inlet main valve are reduced, the fuel cell air outlet main valve is kept open and the blind end air bypass valve is closed, and the voltage of the fuel cell inlet end and the blind end single cell are monitored in real time. When the voltage of a single cell at the air inlet is close to the preset upper limit or the voltage of a single cell at the blind end is close to the preset lower limit, the opening and closing states of the main air inlet and outlet valves and the blind end air bypass valves are switched. The pressure distribution of the air flow field in the stack is changed through the blind end bypass pipeline, so that the pressure difference between the air inlet and outlet of each single cell approaches the same. The valve opening is continuously adjusted to maintain the voltage of each cell in the fuel cell stack within the preset range until a normal operation command is received, at which point each valve is restored to its initial normal operation state.

[0031] It should be noted that this method controls the valve status and air flow path in stages under idling conditions. In the early stage of idling, it initially controls the overall voltage of the fuel cell stack by reducing the intake air volume. When the voltage of a single cell shows a dispersion trend, it switches the air flow field by bypassing the blind end. This fundamentally solves the voltage dispersion problem caused by the uneven pressure difference and large flow difference between the intake end and the blind end of the single cell under idling conditions in traditional fuel cell stacks. It avoids the situation where the voltage of the intake end single cell exceeds the upper limit and the voltage of the blind end single cell falls below the lower limit, thus ensuring the long-term effectiveness of the idling voltage control strategy. At the same time, it does not require major modifications to the core structure of the fuel cell stack. It can achieve precise and balanced control of the single cell voltage simply by switching the flow path and controlling the valve.

[0032] Preferably, the blind-end air bypass includes a blind-end exhaust bypass disposed between the blind end of the fuel cell stack and the air outlet main line, and the blind-end air bypass valve includes a blind-end exhaust valve disposed in the blind-end exhaust bypass; when switching the valve opening and closing state, the main air outlet valve of the fuel cell stack is closed and the blind-end exhaust valve is opened, so that air enters the fuel cell stack through the main air inlet valve of the fuel cell stack and is discharged from the blind-end exhaust bypass of the blind end of the fuel cell stack, thereby changing the air pressure gradient along the airflow direction in the fuel cell stack and reducing the air inlet and outlet pressure difference between the fuel cell stack air inlet end and each cell in the blind end.

[0033] Specifically, a blind-end exhaust bypass connected to the cathode flow field inside the fuel cell stack is set at the cathode blind-end plate. The other end of the blind-end exhaust bypass is connected between the air outlet main line and the tailpipe of the fuel cell system. The blind-end exhaust valve is installed in series in the pipeline of the blind-end exhaust bypass and its opening and closing status and flow opening can be adjusted by the controller. When the valve switching condition is triggered under idling conditions, the controller first sends a closing command to the main air outlet valve of the fuel cell stack. After the main outlet valve is completely closed, it sends an opening command to the blind-end exhaust valve, so that the air output by the air compressor enters the air inlet end of the fuel cell stack through the air inlet main valve, flows along the internal flow channel of the fuel cell stack towards the blind end, and finally flows out from the blind-end exhaust bypass at the blind end and merges into the tailpipe of the system. After the air flow path is switched, the highest air pressure point in the fuel cell stack shifts from the original air inlet end to the blind end, forming a reverse pressure gradient along the airflow direction, so that the inlet and outlet pressure difference of each cell in the fuel cell stack gradually becomes uniform.

[0034] It should be noted that by adding an exhaust bypass at the blind end, the air discharge position can be switched during idling. The pressure distribution inside the stack can be adjusted without changing the air intake direction, which greatly reduces the pressure difference and flow difference between the intake end and the blind end single cell. This effectively suppresses the problem of continuous voltage increase of the intake end single cell. At the same time, the flow path switching control logic is simple and does not require major modifications to the original system's main intake path. It has strong adaptability and can be directly applied to existing fuel cell systems of the same type.

[0035] More preferably, while maintaining the voltage of each cell in the stack within a preset range, the opening of the blind-end exhaust valve is dynamically adjusted using the real-time voltage of each cell as a feedback signal, continuously adjusting the pressure distribution of the airflow field inside the stack, so that the air inlet and outlet pressure difference of each cell in the stack remains close to uniform.

[0036] Specifically, during the idle maintenance phase when the blind-end exhaust valve is open and the fuel cell stack enters reverse exhaust mode, the controller continuously collects real-time voltage data of each cell in the fuel cell stack at a fixed frequency through a voltage monitoring device. The controller compares all collected cell voltage data with a preset voltage range and calculates the voltage difference between the intake end and the blind-end cells. Based on the voltage comparison results and the pressure difference data, the controller sends an opening adjustment signal to the blind-end exhaust valve. When the overall cell voltage is higher than the preset range, the controller reduces the flow opening of the blind-end exhaust valve to reduce the airflow in the fuel cell stack. When the overall cell voltage is lower than the preset range, the controller increases the flow opening of the blind-end exhaust valve to increase the airflow in the fuel cell stack. When the voltage difference between the intake end and the blind-end cells widens, the controller adjusts the opening of the blind-end exhaust valve accordingly to optimize the pressure distribution inside the fuel cell stack and keep the pressure difference between each cell uniform.

[0037] It should be noted that by using closed-loop feedback control to dynamically adjust the opening of the blind-end exhaust valve, the flow field state can be flexibly adjusted according to the real-time changes in the voltage of the individual cells in the fuel cell stack under idling conditions. This not only stabilizes the overall voltage of the fuel cell stack within the preset range, but also continuously suppresses the expansion of the voltage dispersion of individual cells, ensuring the consistency of the voltage of each individual cell under long-term idling conditions and avoiding voltage fluctuations and control failures caused by fixed opening control.

[0038] Preferably, the blind-end air bypass includes a blind-end air intake bypass disposed between the fuel cell stack air inlet main and the fuel cell stack blind end, and the blind-end air bypass valve includes a blind-end air intake valve disposed in the blind-end air intake bypass; when switching the valve opening and closing state, the fuel cell stack air inlet main valve is closed and the blind-end air intake valve is opened, so that air enters the fuel cell stack from the fuel cell stack blind end through the blind-end air intake bypass and is discharged from the fuel cell stack air outlet main valve, thereby reversing the air flow direction and pressure gradient in the fuel cell stack, reducing the air inlet and outlet pressure difference of each cell at the fuel cell stack blind end and air intake end, and balancing the air flow and voltage level of each cell in the fuel cell stack.

[0039] Specifically, a blind-end air intake bypass, connected to the cathode flow field inside the fuel cell stack, is installed at the cathode blind-end plate of the fuel cell stack. The other end of the blind-end air intake bypass is connected to the air inlet main line upstream of the air compressor outlet and the air inlet main valve of the fuel cell system. The blind-end air intake valve is installed in series in the pipeline of the blind-end air intake bypass, and its opening and closing status and flow opening can be adjusted by the controller. When the valve switching condition is triggered under idling conditions, the controller first sends a closing command to the fuel cell stack air inlet main valve. After the inlet main valve is completely closed, it then sends an opening command to the blind-end air intake valve. The command causes the air output from the air compressor to enter the blind end of the fuel cell stack directly through the blind end intake bypass. The air then flows along the internal flow channel of the fuel cell stack towards the original intake end, and finally flows out from the original air outlet main valve of the fuel cell stack, merging into the system tailpipe. After the air flow path is switched, the air flow direction in the fuel cell stack is completely reversed, and the highest pressure point shifts from the original intake end to the blind end, forming a pressure gradient that is completely opposite to the original forward flow path. This allows the blind end cell, which originally had the smallest flow rate, to obtain sufficient air flow, reducing the pressure difference and flow rate difference between the blind end and the intake end cells.

[0040] It should be noted that by adding an intake bypass at the blind end, the airflow direction inside the fuel cell stack is completely reversed under idling conditions, which fundamentally solves the problem of insufficient air supply and continuous voltage reduction of the blind end single cell in the traditional forward flow path. By reversing the air intake, the blind end single cell obtains higher intake pressure and flow, effectively balancing the voltage levels of the first and last single cells of the fuel cell stack. At the same time, the flow path switching only requires controlling the opening and closing of two valves, making the control logic simple and the operation highly reliable.

[0041] More preferably, while maintaining the voltage of each cell in the stack within a preset range, the opening of the blind end air inlet valve is dynamically adjusted using the real-time voltage of each cell as a feedback signal, and the pressure distribution of the air flow field inside the stack is continuously adjusted so that the air inlet and outlet pressure difference of each cell in the stack remains close to the same.

[0042] Specifically, during the idle speed maintenance phase when the blind-end intake valve is open and the fuel cell stack enters reverse intake, the controller continuously collects real-time voltage data of each cell in the fuel cell stack at a fixed frequency through a voltage monitoring device. It compares all collected cell voltage data with a preset voltage range and calculates the voltage difference between the blind-end and intake-end cells. Based on the voltage comparison results and pressure difference data, the controller sends an opening adjustment signal to the blind-end intake valve. When the overall cell voltage is higher than the preset range, the controller reduces the flow opening of the blind-end intake valve to decrease the air intake volume in the fuel cell stack. When the overall cell voltage is lower than the preset range, the controller increases the flow opening of the blind-end intake valve to increase the air intake volume in the fuel cell stack. When the voltage difference between the blind-end and intake-end cells widens, the controller adjusts the opening of the blind-end intake valve accordingly to optimize the pressure distribution inside the fuel cell stack, ensuring that the inlet and outlet pressure difference of each cell remains uniform.

[0043] It should be noted that the blind-end intake valve opening can be dynamically adjusted through closed-loop feedback control. The intake volume and flow field state can be flexibly adjusted according to the real-time changes in the voltage of the individual cells in the fuel cell stack under idling conditions, accurately compensating for the air supply of the individual cells in the blind end. This not only stabilizes the overall voltage of the fuel cell stack within the preset range, but also continuously reduces the voltage difference between individual cells, ensuring the stability and effectiveness of voltage control under long-term idling conditions, and avoiding the problem of reverse voltage dispersion at the beginning and end caused by the fixed opening control of reverse intake.

[0044] Preferably, the blind-end air bypass includes a blind-end air intake bypass and a blind-end air exhaust bypass. The blind-end air intake bypass is located between the fuel cell stack air inlet main and the fuel cell stack blind end, and the blind-end air exhaust bypass is located between the fuel cell stack blind end and the air outlet main. The blind-end air bypass valve includes a blind-end air intake valve located in the blind-end air intake bypass and a blind-end air exhaust valve located in the blind-end air exhaust bypass. When switching the valve opening and closing state, the air flow path and pressure distribution mode in the fuel cell stack are switched by the combination of opening and closing of the blind-end air intake valve and the blind-end air exhaust valve, so that the air inlet and outlet pressure difference of each cell in the fuel cell stack remains close to the same.

[0045] Specifically, a blind-end intake bypass and a blind-end exhaust bypass are simultaneously installed at the cathode blind end plate of the fuel cell stack. The upstream end of the blind-end intake bypass is connected to the air inlet main line upstream of the air compressor outlet and the air inlet main valve, and the downstream end is connected to the internal flow field of the fuel cell stack blind end. The blind-end intake valve is installed in series in the blind-end intake bypass. The upstream end of the blind-end exhaust bypass is connected to the internal flow field of the fuel cell stack blind end, and the downstream end is connected to the air outlet main line downstream of the air outlet main valve and the tailpipe. The blind-end exhaust valve is installed in series in the blind-end exhaust bypass. During idle operation, the controller can switch the flow path by different valve opening and closing combinations according to the voltage status of the individual cells of the fuel cell stack. It can choose to close the air outlet main valve and open the blind-end exhaust valve to achieve reverse exhaust mode, or close the air inlet main valve and open the blind-end intake valve to achieve reverse intake mode, or simultaneously open the blind-end intake valve and the blind-end exhaust valve, and coordinate with the opening degree adjustment of the inlet and outlet main valves to achieve bidirectional flow field adjustment mode. By switching between different modes, the pressure distribution inside the fuel cell stack is continuously optimized.

[0046] It should be noted that by simultaneously setting up blind-end intake and exhaust dual bypasses, the internal airflow field of the fuel cell stack can be flexibly adjusted in multiple modes. Compared with the single bypass structure, it can adapt to more complex idling conditions and single-cell voltage variation scenarios. The optimal flow path adjustment mode can be selected according to the specific situation of voltage dispersion, continuously ensuring the consistency of the inlet and outlet pressure difference of each single cell, further improving the flexibility and accuracy of idling voltage control. At the same time, the dual bypass structure can be redundant to each other, improving the reliability of system operation.

[0047] More preferably, during idling operation, depending on the dispersion of the voltage of each cell in the fuel cell stack, the idling duration or the number of idling operations, the system alternates between the intake reverse flow mode with the blind intake bypass and the exhaust reverse flow mode with the blind exhaust bypass, continuously balancing the airflow and voltage level of each cell in the fuel cell stack, and maintaining the voltage of all cells stably within a preset range.

[0048] Specifically, during idling operation, the controller records the continuous idling time and cumulative idling frequency in real time, while simultaneously calculating the voltage dispersion of each cell in the fuel cell stack using a voltage monitoring device. The controller has preset switching thresholds. When the continuous idling time reaches a preset duration threshold, the cumulative idling frequency reaches a preset frequency threshold, or the single-cell voltage dispersion reaches a preset dispersion threshold, the controller immediately sends a switching command to each valve, switching between the intake reverse flow mode and the exhaust reverse flow mode. After the mode switch is complete, the controller resumes recording the idling time and continuously monitors the single-cell voltage dispersion. When the switching threshold is reached again, the mode switch is performed again, thus achieving alternating operation of the two reverse flow modes throughout the idling process.

[0049] It should be noted that by alternating between the two reverse flow modes, the problems of uneven local flow field in the stack and reverse voltage dispersion of individual cells caused by a single reverse flow path for a long time can be avoided. By periodically switching the flow path, the air flow of each individual cell in the stack is continuously balanced. No matter how long the idling condition lasts, the voltage of all individual cells can be stably maintained within the preset range. This completely solves the problem of long-term failure of traditional idling control strategies and greatly improves the stability and durability of fuel cell idling operation.

[0050] Preferably, upon receiving a normal operation command, the blind-end air bypass valve is first closed, and then the main air inlet valve and the main air outlet valve of the fuel cell stack are simultaneously restored to the fully open state for normal operation. At the same time, the output power of the air compressor is increased, so that the fuel cell stack smoothly exits the idling condition and enters the normal operation state, allowing air to flow through the fuel cell stack along a preset positive path.

[0051] Specifically, when the controller receives a normal operation command from the vehicle controller or system controller, it first sends a fully closed command to the blind-end air bypass valve, which is in the open state. After confirming that the blind-end air bypass valve is completely closed, it sends a fully open command to the fuel cell stack air inlet main valve and air outlet main valve to restore the two main valves to the fully open state corresponding to normal operation. At the same time, it sends a control signal to the air compressor to increase the operating speed and output power of the air compressor, so that the air output by the air compressor enters the fuel cell stack through the air inlet main valve along the preset positive path, and then flows out through the air outlet main valve, so that the fuel cell stack can smoothly complete the switch from idle condition to normal operation condition.

[0052] It should be noted that by setting a fixed operating condition switching sequence, closing the blind-end bypass valve first and then restoring the main valve state, problems such as air flow path short circuit and sudden changes in intake volume during the operating condition switching process can be avoided, preventing large fluctuations in single-cell voltage and ensuring the stability of the fuel cell stack operation during the operating condition switching process. At the same time, the original forward flow path under normal operating conditions is completely restored, which will not have any impact on the rated power operation of the fuel cell stack, thus balancing the idle speed control effect and the performance requirements of normal operation.

[0053] Preferably, the blind-end air bypass is connected to the internal flow field of the fuel cell stack through a blind-end air tube sheet installed at the blind end of the fuel cell stack. The blind-end air tube sheet is located at the cathode blind end plate where the fuel cell stack originally had no fluid inlet or outlet.

[0054] Specifically, a blind-end air tube sheet is installed at the cathode blind-end plate of the fuel cell stack. One side of the blind-end air tube sheet is connected to the cathode flow channel inside the fuel cell stack, and the other side is provided with an interface for docking with the blind-end air bypass pipeline. This allows the blind-end air bypass pipeline to form a complete connected flow path with the cathode flow field inside the fuel cell stack through the blind-end air tube sheet. The blind-end air tube sheet is installed at the position of the original cathode blind-end plate of the fuel cell stack, replacing part of the sealing and flow guiding functions of the original blind-end plate. No modifications are required to the core components inside the fuel cell stack, such as bipolar plates and membrane electrodes. The bypass flow path docking can be completed simply by installing the tube sheet at the original blind-end position.

[0055] It should be noted that the blind-end air tube sheet enables the connection between the blind-end bypass and the internal flow field of the fuel cell stack. The structure is simple and highly adaptable, and it can be directly adapted to existing conventional fuel cell stacks without requiring significant adjustments to the core structure and manufacturing process of the stack. This reduces the cost and difficulty of technology application modification. At the same time, the blind-end air tube sheet can ensure uniform connection between the bypass and the flow field of the fuel cell stack, avoiding the problem of local flow field disturbance caused by bypass connection, and ensuring the uniformity and effectiveness of flow field regulation.

[0056] More preferably, the blind-end air tube plate is provided with a through hole communicating with the corresponding blind-end air bypass, and the blind-end air tube plate and the cathode blind-end plate are independent separate structures, or integrated with the cathode blind-end plate as a whole structure.

[0057] Specifically, according to the blind-end air bypass configuration scheme, corresponding through holes are opened on the blind-end air tube sheet. When only a blind-end exhaust bypass is configured, an exhaust through hole connected to the blind-end exhaust bypass is opened on the tube sheet. When only a blind-end intake bypass is configured, an intake through hole connected to the blind-end intake bypass is opened on the tube sheet. When both blind-end intake and exhaust bypasses are configured simultaneously, corresponding intake and exhaust through holes are opened on the tube sheet respectively. All through holes are uniformly connected to the cathode flow channel inside the fuel cell stack. In the actual production and assembly process, the blind-end air tube sheet and the cathode blind-end plate can be processed into two independent separate parts and fastened together as a whole by sealing during assembly. Alternatively, the structure of the blind-end air tube sheet and the cathode blind-end plate can be integrated and processed into a single part, which can be directly used as the cathode blind-end plate of the fuel cell stack.

[0058] It should be noted that by setting corresponding through holes on the blind-end air pipe plate, the bypass airflow and the internal flow field of the fuel cell stack can be uniformly connected, realizing the synchronous adjustment of the flow field of each cell in the entire stack and ensuring the consistency of the differential pressure adjustment of each cell. At the same time, the two structural designs, split and integrated, can be adapted to different production processes and assembly requirements. The split structure can directly modify and upgrade existing fuel cell stacks, while the integrated structure can reduce the number of parts, reduce assembly difficulty, and improve the system integration and operational reliability.

[0059] Example 2 This embodiment is based on embodiment 1: This embodiment provides a fuel cell idle voltage control method, specifically a single blind-end exhaust bypass fuel cell idle voltage control scheme, which is described in detail below.

[0060] I. System Structure like Figure 4 As shown, the fuel cell system in this embodiment includes a fuel cell stack, an air compressor, an air inlet main valve M1, an air outlet main valve M2, a blind-end exhaust valve M3, a blind-end air tube sheet, a voltage monitoring device, and a system controller.

[0061] In this fuel cell stack, both the air inlet and air outlet are located on the same end plate side, while the other end of the stack is a cathode blind end plate without any existing fluid inlet or outlet. The blind end air pipe plate is installed correspondingly at the cathode blind end plate; the two can be assembled separately with a sealed assembly or integrated into a single structure. Figure 7 As shown, the blind-end air pipe plate is provided with an exhaust port for connecting the bypass. One end of the blind-end exhaust bypass is connected to the entire cathode flow field inside the fuel cell stack through the exhaust port. The other end of the blind-end exhaust bypass is connected to the tailpipe downstream of the fuel cell stack air outlet main. The blind-end exhaust valve M3 is installed in series in the pipeline of the blind-end exhaust bypass to control the opening and closing of the bypass and the flow degree.

[0062] The air inlet main valve M1 is installed in the air inlet main line between the air compressor outlet and the fuel cell stack air inlet, and is used to control the on / off and opening degree of the forward air intake of the fuel cell stack; the air outlet main valve M2 is installed in the air outlet main line between the fuel cell stack air outlet and the tailpipe, and is used to control the on / off and opening degree of the forward exhaust of the fuel cell stack; the voltage monitoring device is electrically connected to each cell in the fuel cell stack, and is used to collect the voltage data of each cell in real time and transmit it to the system controller; the system controller is connected to the air compressor, air inlet main valve M1, air outlet main valve M2, blind end exhaust valve M3, and voltage monitoring device respectively, and is used to issue control commands and receive feedback signals.

[0063] II. Idle Speed ​​Voltage Control Scheme 1. Normal operation phase When the fuel cell system is operating at rated power, the system controller keeps the air inlet main valve M1 and the air outlet main valve M2 fully open, and keeps the blind end exhaust valve M3 fully closed. The air compressor operates at rated power, and the output air enters the cathode flow field inside the stack through the air inlet main valve M1, flows through each cell, and then flows out from the stack air outlet. It then flows through the air outlet main valve M2 and is discharged into the tailpipe. At this time, the air flow field inside the stack is in a positive flow mode, which meets the air supply requirements for normal operation of the stack.

[0064] 2. Initial Idle Speed ​​Control Phase When the system controller receives the idle speed operation command, it immediately enters the initial idle speed control stage: the controller sends a power reduction command to the air compressor to reduce the operating speed and output power of the air compressor, and simultaneously sends an opening adjustment command to the air inlet main valve M1 to reduce the flow opening of M1, while keeping the air outlet main valve M2 fully open and the blind end exhaust valve M3 fully closed, thereby reducing the overall air intake of the fuel cell stack and initially controlling the average single cell voltage of the fuel cell stack within the preset range; during this process, the voltage monitoring device collects the real-time voltage of the single cells at the air inlet end of the fuel cell stack near the air inlet and the single cells at the blind end far from the air inlet and outlet at a preset frequency, and transmits the voltage data to the controller in real time, and the controller continuously monitors the voltage change trend of each single cell in the fuel cell stack.

[0065] 3. Idle flow path switching stage During the initial idle control phase, when the controller receives a signal from the voltage monitoring device and confirms that the voltage of the single cell at the intake end is close to the preset upper limit or the voltage of the single cell at the blind end is close to the preset lower limit, it immediately triggers the flow path switching procedure: the controller first sends a fully closed command to the air outlet main valve M2, and after confirming that M2 is completely closed, it sends an open command to the blind end exhaust valve M3 to complete the switching of the air flow path; at this time, the air output from the air compressor enters the fuel cell intake end through the air inlet main valve M1, flows along the cathode flow channel inside the fuel cell towards the blind end, and finally enters the blind end exhaust bypass through the exhaust port of the blind end air pipe plate, and is discharged into the tailpipe through the blind end exhaust valve M3, corresponding to the attached Figure 3 The air pressure distribution state is determined, the air pressure gradient along the airflow direction in the stack is reconstructed, the air inlet and outlet pressure difference of each cell at the air inlet end and the blind end is greatly reduced, and the inlet and outlet pressure difference of each cell approaches the same.

[0066] 4. Idle voltage maintenance phase After the flow path switching is completed, the system enters the idle voltage maintenance phase: the controller uses the voltage of each individual cell collected in real time by the voltage monitoring device as a closed-loop feedback signal to dynamically adjust the flow opening of the blind-end exhaust valve M3; when the overall individual cell voltage of the fuel cell stack is higher than the preset voltage range, the controller reduces the opening of the blind-end exhaust valve M3 to reduce the air flow in the fuel cell stack, so that the overall voltage falls back to the preset range; when the overall individual cell voltage of the fuel cell stack is lower than the preset voltage range, the controller increases the opening of the blind-end exhaust valve M3 to increase the air flow in the fuel cell stack, so that the overall voltage rises back to the preset range; at the same time, the controller continuously monitors the voltage dispersion of each individual cell, and continuously optimizes the pressure distribution in the fuel cell stack by fine-tuning the opening of the blind-end exhaust valve M3, so that the inlet and outlet pressure difference of each individual cell remains close to the same, and the voltage of all individual cells is stably maintained within the preset range.

[0067] 5. Operational recovery phase During the idle voltage maintenance phase, when the system controller receives a normal operation command, it immediately enters the operating condition recovery procedure: the controller first sends a fully closed command to the blind end exhaust valve M3, and after confirming that M3 is completely closed, it sends a fully open command to the air outlet main valve M2, and simultaneously sends a fully open command to the air inlet main valve M1 and a power increase command to the air compressor, restoring the air compressor power and the status of each valve to the initial state of normal operation, so that the fuel cell stack smoothly exits the idle condition and re-enters the normal operating forward flow mode.

[0068] It should be noted that this embodiment, by adding a single exhaust bypass at the blind end of the fuel cell stack, can reconstruct the pressure distribution of the flow field within the stack under idling conditions simply by adjusting the opening and closing of three valves. This fundamentally solves the core problem of traditional fuel cell stacks with the same inlet and outlet sides under idling conditions: large pressure difference and high flow rate at the inlet end cause the voltage to exceed the upper limit, while small pressure difference and low flow rate at the blind end cause the voltage to fall below the lower limit. This effectively suppresses the problem of the voltage dispersion of single cells increasing with idling time, ensuring the effectiveness of the voltage control strategy under long-term idling conditions. Furthermore, this embodiment only requires adding an air pipe plate with through holes to the existing fuel cell stack blind end to complete the system modification, without modifying core components such as bipolar plates and membrane electrode assemblies inside the stack. The modification cost is low, the adaptability is strong, and the control logic is simple and reliable, making it directly applicable to existing conventional fuel cell systems with the same inlet and outlet sides.

[0069] Example 3 This embodiment is based on embodiment 1: This embodiment provides a fuel cell idle voltage control method, specifically a single blind-end intake bypass fuel cell idle voltage control scheme, which is described in detail below.

[0070] I. System Structure like Figure 5 As shown, the fuel cell system in this embodiment includes a fuel cell stack, an air compressor, an air inlet main valve M1, an air outlet main valve M2, a blind-end air inlet valve M4, a blind-end air tube sheet, a voltage monitoring device, and a system controller.

[0071] In this fuel cell stack, both the air inlet and air outlet are located on the same end plate side, while the other end of the stack is a cathode blind end plate without any existing fluid inlet or outlet. The blind end air pipe plate is installed correspondingly at the cathode blind end plate; the two can be assembled separately with a sealed assembly or integrated into a single structure. Figure 7As shown, an air inlet hole for connecting the bypass is provided on the blind end air pipe plate. One end of the blind end air inlet bypass is connected to the entire cathode flow field inside the fuel cell stack through the air inlet hole. The other end of the blind end air inlet bypass is connected to the air inlet main line upstream of the air compressor outlet and the air inlet main valve M1. The blind end air inlet valve M4 is installed in series in the pipeline of the blind end air inlet bypass to control the opening and closing of the bypass and the flow degree.

[0072] The air inlet main valve M1 is installed downstream of the blind-end air intake bypass docking point and in the air inlet main line before the fuel cell air inlet, and is used to control the on / off and opening degree of the forward air intake of the fuel cell; the air outlet main valve M2 is installed in the air outlet main line between the fuel cell air outlet and the tailpipe, and is used to control the on / off and opening degree of the fuel cell exhaust; the voltage monitoring device is electrically connected to each cell in the fuel cell, and is used to collect the voltage data of each cell in real time and transmit it to the system controller; the system controller is connected to the air compressor, air inlet main valve M1, air outlet main valve M2, blind-end air intake valve M4, and voltage monitoring device, respectively, and is used to issue control commands and receive feedback signals.

[0073] II. Idle Speed ​​Voltage Control Scheme 1. Normal operation phase When the fuel cell system is operating normally at rated power, the system controller keeps the air inlet main valve M1 and the air outlet main valve M2 fully open, and keeps the blind end inlet valve M4 fully closed. The air compressor operates at rated power, and the output air enters the cathode flow field inside the stack through the air inlet main valve M1, flows through each cell, and then flows out from the stack air outlet. It then flows through the air outlet main valve M2 and is discharged into the tailpipe. At this time, the air flow field inside the stack is in a positive flow mode, which meets the air supply requirements for normal operation of the stack.

[0074] 2. Initial Idle Speed ​​Control Phase When the system controller receives the idle speed operation command, it immediately enters the initial idle speed control stage: the controller sends a power reduction command to the air compressor to reduce the operating speed and output power of the air compressor, and simultaneously sends an opening adjustment command to the air inlet main valve M1 to reduce the flow opening of M1, while keeping the air outlet main valve M2 fully open and the blind end air inlet valve M4 fully closed, thereby reducing the overall air intake of the fuel cell stack and initially controlling the average single cell voltage of the fuel cell stack within the preset range; during this process, the voltage monitoring device collects the real-time voltage of the single cells at the air inlet end of the fuel cell stack near the air inlet and the single cells at the blind end far from the air inlet and outlet at a preset frequency, and transmits the voltage data to the controller in real time, and the controller continuously monitors the voltage change trend of each single cell in the fuel cell stack.

[0075] 3. Idle flow path switching stage During the initial idle control phase, when the controller receives a signal from the voltage monitoring device and confirms that the voltage of the single cell at the intake end is close to the preset upper limit or the voltage of the single cell at the blind end is close to the preset lower limit, it immediately triggers the flow path switching procedure: the controller first issues a fully closed command to the air inlet main valve M1, and after confirming that M1 is completely closed, it issues an open command to the blind end intake valve M4 to complete the switching of the air flow path; at this time, the air output from the air compressor enters the blind end of the fuel cell stack through the blind end intake bypass and the blind end intake valve M4, flows along the cathode flow channel inside the fuel cell stack towards the original intake end, and finally flows out from the original air outlet of the fuel cell stack, and is discharged through the air outlet main valve M2 into the tailpipe. Figure 3 The air pressure distribution state is such that the air flow direction and pressure gradient in the stack are completely reversed. The blind end cell, which originally had the smallest flow rate, becomes the air inlet head, which greatly reduces the air inlet and outlet pressure difference between the blind end and the air inlet and outlet cells of each cell, making the inlet and outlet pressure difference of each cell approach the same.

[0076] 4. Idle voltage maintenance phase After the flow path switching is completed, the system enters the idle voltage maintenance phase: the controller uses the voltage of each individual cell collected in real time by the voltage monitoring device as a closed-loop feedback signal to dynamically adjust the flow opening of the blind end air intake valve M4; when the overall individual cell voltage of the fuel cell stack is higher than the preset voltage range, the controller reduces the opening of the blind end air intake valve M4 to reduce the air intake in the fuel cell stack, so that the overall voltage falls back to the preset range; when the overall individual cell voltage of the fuel cell stack is lower than the preset voltage range, the controller increases the opening of the blind end air intake valve M4 to increase the air intake in the fuel cell stack, so that the overall voltage rises back to the preset range; at the same time, the controller continuously monitors the voltage dispersion of each individual cell, and continuously optimizes the pressure distribution in the fuel cell stack by fine-tuning the opening of the blind end air intake valve M4, so that the inlet and outlet pressure difference of each individual cell remains close to the same, and the voltage of all individual cells is stably maintained within the preset range.

[0077] 5. Operational recovery phase During the idle voltage maintenance phase, when the system controller receives the normal operation command, it immediately enters the operating condition recovery procedure: the controller first sends a fully closed command to the blind end intake valve M4, and after confirming that M4 is completely closed, it sends a fully open command to the air inlet main valve M1, and simultaneously sends a power increase command to the air compressor, restoring the air compressor power and the status of each valve to the initial state of normal operation, so that the fuel cell stack smoothly exits the idle condition and re-enters the normal operating forward flow mode.

[0078] It should be noted that this embodiment addresses the core issue of insufficient air supply and continuous voltage drop in blind-end cells under idling conditions in traditional same-side inlet / outlet cells by adding a single air intake bypass at the blind end of the fuel cell stack and reconstructing the pressure gradient by reversing the airflow direction within the stack. This fundamentally solves the problem. By reversing the air intake, the blind-end cells receive sufficient and stable airflow, effectively balancing the voltage levels of the first and last cells in the stack and preventing the voltage dispersion from continuously increasing under idling conditions. Furthermore, this embodiment only requires adding an air pipe plate with air intake holes to the existing blind end of the fuel cell stack to complete the system modification. No changes are needed to the core components inside the stack, resulting in low modification costs, strong adaptability, and simple and reliable control logic. It can specifically address the pain point of undervoltage idling control in blind-end cells.

[0079] Example 4 This embodiment is based on embodiment 1: This embodiment provides a fuel cell idle voltage control method, specifically a blind-end intake + exhaust dual-bypass fuel cell idle voltage control scheme, which is described in detail below.

[0080] I. System Structure like Figure 6 As shown, the fuel cell system in this embodiment includes a fuel cell stack, an air compressor, an air inlet main valve M1, an air outlet main valve M2, a blind end exhaust valve M3, a blind end intake valve M4, a blind end air tube sheet, a voltage monitoring device, and a system controller.

[0081] In this fuel cell stack, both the air inlet and air outlet are located on the same end plate side, while the other end of the stack is a cathode blind end plate without any existing fluid inlet or outlet. The blind end air pipe plate is installed correspondingly at the cathode blind end plate; the two can be assembled separately with a sealed assembly or integrated into a single structure. Figure 7 As shown, the blind-end air duct plate is provided with both an air inlet and an air outlet, which are used to connect to the two bypasses respectively.

[0082] One end of the blind-end intake bypass is connected to the entire cathode flow field inside the fuel cell stack through the intake port of the blind-end air pipe plate, and the other end is connected to the air inlet main line upstream of the air compressor outlet and the air inlet main valve M1. The blind-end intake valve M4 is installed in series in the pipeline of the blind-end intake bypass. One end of the blind-end exhaust bypass is connected to the entire cathode flow field inside the fuel cell stack through the exhaust port of the blind-end air pipe plate, and the other end is connected to the tail exhaust pipeline downstream of the fuel cell stack air outlet main line. The blind-end exhaust valve M3 is installed in series in the pipeline of the blind-end exhaust bypass.

[0083] The air inlet main valve M1 is installed in the air inlet main line downstream of the blind end air intake bypass docking point and before the fuel cell stack air inlet. The air outlet main valve M2 is installed in the air outlet main line upstream of the fuel cell stack air outlet and the blind end exhaust bypass docking point. The voltage monitoring device is electrically connected to each cell in the fuel cell stack and is used to collect the voltage data of each cell in real time and transmit it to the system controller. The system controller is connected to the air compressor, air inlet main valve M1, air outlet main valve M2, blind end exhaust valve M3, blind end air intake valve M4, and voltage monitoring device for issuing control commands and receiving feedback signals.

[0084] II. Idle Speed ​​Voltage Control Scheme 1. Normal operation phase When the fuel cell system is operating at rated power, the system controller keeps the air inlet main valve M1 and the air outlet main valve M2 fully open, and keeps the blind end exhaust valve M3 and the blind end intake valve M4 fully closed. The air compressor operates at rated power, and the output air enters the cathode flow field inside the stack through the air inlet main valve M1, flows through each cell, and then flows out from the stack air outlet. It then flows through the air outlet main valve M2 and is discharged into the tailpipe. At this time, the air flow field inside the stack is in a positive flow mode, which meets the air supply requirements for normal operation of the stack.

[0085] 2. Initial Idle Speed ​​Control Phase When the system controller receives the idle speed operation command, it immediately enters the initial idle speed control stage: the controller sends a power reduction command to the air compressor to reduce the operating speed and output power of the air compressor, and simultaneously sends an opening adjustment command to the air inlet main valve M1 to reduce the flow opening of M1, while keeping the air outlet main valve M2 fully open and the blind end exhaust valve M3 and blind end intake valve M4 fully closed, thereby reducing the overall air intake of the fuel cell stack and initially controlling the average single cell voltage of the fuel cell stack within the preset range; during this process, the voltage monitoring device collects the real-time voltage of the fuel cell stack intake end and blind end single cells at a preset frequency, calculates the single cell voltage dispersion, records the idle speed operation time and the cumulative number of idle speeds, and transmits the relevant data to the controller in real time.

[0086] 3. Idle flow path switching and alternation control stage During continuous operation in the initial idle control phase, when the controller receives a signal from the voltage monitoring device and confirms that the intake single-cell voltage is close to the preset upper voltage limit or the blind single-cell voltage is close to the preset lower voltage limit, it immediately triggers the flow path switching program and enters the dual bypass alternating control mode. In the first stage, the controller first sends a fully closed command to the air inlet main valve M1 and the blind-end exhaust valve M3. After confirming that both valves are completely closed, it then sends an open command to the blind-end intake valve M4 and the air outlet main valve M2, switching to the reverse intake flow mode. At this time, air enters the blind end of the fuel cell stack through the blind-end intake bypass and is discharged from the original air outlet, corresponding to the attached... Figure 3 The pressure distribution state is reversed, the pressure gradient inside the stack is reversed, the air supply of the blind end cells is compensated, and the pressure difference between the individual cells is reduced. In the second stage, when the reverse intake mode continues to run until the preset idling time or cumulative idling number, or when the single cell voltage dispersion is detected to reach the preset threshold again, the controller sends a full-close command to the blind-end intake valve M4 and the air outlet main valve M2. After confirming that the two valves are completely closed, the controller sends an opening command to the air inlet main valve M1 and the blind-end exhaust valve M3, switching to the reverse exhaust flow mode. At this time, air enters the fuel cell stack through the original inlet main valve and is discharged from the blind-end exhaust bypass, reconstructing the pressure gradient in the fuel cell stack and suppressing the trend of increasing single cell voltage at the intake end. Throughout the idling process, the controller alternates between the two reverse flow modes mentioned above, based on the voltage dispersion of a single cell, the duration of idling, or the number of idling operations, to continuously balance the airflow and inlet / outlet pressure difference of each cell in the stack.

[0087] 4. Idle voltage maintenance phase During the alternating operation of the two flow modes, the system synchronously enters the closed-loop voltage maintenance stage: the controller uses the voltage of each cell collected in real time by the voltage monitoring device as feedback signal, and adjusts the flow opening of the blind end air inlet valve M4 or blind end exhaust valve M3 that is currently in the open state accordingly; when the overall cell voltage of the fuel cell stack deviates from the preset range, the valve opening is adjusted to correct the air intake; when the voltage dispersion of the cell increases, the valve opening is finely adjusted to optimize the flow field pressure distribution, so that the air inlet and outlet pressure difference of each cell in the fuel cell stack continues to be close to the same state, and the voltage of all cells is stably maintained within the preset range.

[0088] 5. Operational recovery phase During the idle speed alternation control process, when the system controller receives the normal operation command, it immediately enters the operating condition recovery procedure: the controller first issues a fully closed command to the blind end intake valve M4 and the blind end exhaust valve M3. After confirming that both bypass valves are completely closed, it issues a fully open command to the air inlet main valve M1 and the air outlet main valve M2, and simultaneously issues a power increase command to the air compressor to restore the air compressor power and the status of each valve to the initial state of normal operation, so that the fuel cell stack smoothly exits the idle speed condition and re-enters the normal operation forward flow mode.

[0089] It should be noted that this embodiment achieves flexible adjustment and alternating control of the airflow field within the fuel cell stack through the simultaneous setting of blind-end intake and exhaust dual bypasses. Compared to the single bypass scheme, it can adapt to more complex idling conditions. No matter how long the idling condition lasts, the expansion of single-cell voltage dispersion can be continuously suppressed through alternating mode switching, completely solving the core pain point of long-term failure of traditional idling control strategies. At the same time, the dual bypass structure can achieve mutual redundancy, greatly improving the reliability of system operation. Multiple flow field adjustment modes can be achieved through valve opening and closing combinations, taking into account the accuracy, flexibility and stability of idling voltage control, and maximizing the extension of the fuel cell stack's operating life under idling conditions.

[0090] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0091] It should be noted that, for the sake of simplicity, the foregoing method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0092] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "install", and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a wired connection or a wireless connection.

Claims

1. A fuel cell idle voltage control method, applied to a fuel cell stack with a blind-end air bypass, characterized in that, The method includes: Upon receiving the idle speed operation command, the air compressor output power and the opening of the fuel cell air inlet main valve are reduced, the fuel cell air outlet main valve is kept open and the blind end air bypass valve is closed, and the voltage of the fuel cell inlet end and the blind end single cell are monitored in real time. When the voltage of a single cell at the air inlet is close to the preset upper limit or the voltage of a single cell at the blind end is close to the preset lower limit, the opening and closing states of the main air inlet and outlet valves and the blind end air bypass valves are switched. The pressure distribution of the air flow field in the stack is changed through the blind end bypass pipeline, so that the pressure difference between the air inlet and outlet of each single cell approaches the same. The valve opening is continuously adjusted to maintain the voltage of each cell in the fuel cell stack within the preset range until a normal operation command is received, at which point each valve is restored to its initial normal operation state.

2. The fuel cell idle voltage control method according to claim 1, characterized in that, The blind-end air bypass includes a blind-end exhaust bypass located between the blind end of the fuel cell stack and the air outlet main line. The blind-end air bypass valve includes a blind-end exhaust valve located in the blind-end exhaust bypass. When switching the valve opening and closing state, the main air outlet valve of the fuel cell stack is closed, and the blind-end exhaust valve is opened, so that air enters the fuel cell stack through the main air inlet valve of the fuel cell stack and is discharged from the blind-end exhaust bypass of the fuel cell stack blind end, thereby changing the air pressure gradient along the airflow direction in the fuel cell stack and reducing the air inlet and outlet pressure difference between the fuel cell stack air inlet end and each cell in the blind end.

3. The fuel cell idle voltage control method according to claim 2, characterized in that, While maintaining the voltage of each cell in the stack within a preset range, the opening of the blind-end exhaust valve is dynamically adjusted using the real-time voltage of each cell as a feedback signal. This continuously adjusts the pressure distribution of the airflow field inside the stack, keeping the air inlet and outlet pressure difference of each cell in the stack nearly uniform.

4. The fuel cell idle voltage control method according to claim 1, characterized in that, The blind-end air bypass includes a blind-end air intake bypass located between the fuel cell stack air inlet main and the fuel cell stack blind end. The blind-end air bypass valve includes a blind-end air intake valve located in the blind-end air intake bypass. When switching the valve opening and closing state, the fuel cell stack air inlet main valve is closed and the blind-end air intake valve is opened, so that air enters the fuel cell stack from the blind end through the blind-end air intake bypass and is discharged from the fuel cell stack air outlet main valve. This reverses the air flow direction and pressure gradient in the fuel cell stack, reduces the air inlet and outlet pressure difference of each cell at the fuel cell stack blind end and air intake end, and balances the air flow and voltage level of each cell in the fuel cell stack.

5. The fuel cell idle voltage control method according to claim 4, characterized in that, While maintaining the voltage of each cell in the stack within a preset range, the opening of the blind end air inlet valve is dynamically adjusted using the real-time voltage of each cell as a feedback signal. This continuously adjusts the pressure distribution of the airflow field inside the stack, keeping the air inlet and outlet pressure difference of each cell in the stack nearly uniform.

6. The fuel cell idle voltage control method according to claim 1, characterized in that, The blind-end air bypass includes a blind-end air intake bypass and a blind-end air exhaust bypass. The blind-end air intake bypass is located between the fuel cell stack air inlet main and the fuel cell stack blind end, and the blind-end air exhaust bypass is located between the fuel cell stack blind end and the air outlet main. The blind-end air bypass valve includes a blind-end air intake valve located in the blind-end air intake bypass and a blind-end air exhaust valve located in the blind-end air exhaust bypass. When switching the valve opening and closing state, the air flow path and pressure distribution mode in the fuel cell stack are switched by the combination of opening and closing of the blind-end air intake valve and the blind-end air exhaust valve, so that the air inlet and outlet pressure difference of each cell in the fuel cell stack remains close to the same.

7. The fuel cell idle voltage control method according to claim 6, characterized in that, During idling operation, the system alternates between the intake reverse flow mode with the blind intake bypass and the exhaust reverse flow mode with the blind exhaust bypass, depending on the dispersion of the voltage of each cell in the fuel cell stack, the duration of idling operation, or the number of idling operations. This continuously balances the airflow and voltage level of each cell in the fuel cell stack, and keeps the voltage of all cells stable within a preset range.

8. The fuel cell idle voltage control method according to claim 1, characterized in that, Upon receiving the normal operation command, the blind-end air bypass valve is first closed, and then the main air inlet valve and the main air outlet valve of the fuel cell stack are simultaneously restored to the fully open state for normal operation. At the same time, the output power of the air compressor is increased, so that the fuel cell stack smoothly exits the idling condition and enters the normal operation state, allowing air to flow through the fuel cell stack along the preset positive path.

9. The fuel cell idle voltage control method according to any one of claims 1 to 8, characterized in that, The blind-end air bypass is connected to the internal flow field of the fuel cell stack through a blind-end air tube sheet installed at the blind end of the fuel cell stack. The blind-end air tube sheet is located at the cathode blind end plate where the fuel cell stack originally had no fluid inlet or outlet.

10. The fuel cell idle voltage control method according to claim 9, characterized in that, The blind-end air tube plate is provided with through holes that communicate with the corresponding blind-end air bypass. The blind-end air tube plate and the cathode blind-end plate are independent separate structures, or they are integrated into a single structure.

Images