Fuel cell system and water content dynamic adjusting method

Abstract

The invention provides a fuel cell system and a dynamic water content adjusting method, and relates to the technical field of fuel cells, the fuel cell system comprises a controller, an electric pile, and a current acquisition module, an air path subsystem, a hydrogen path subsystem and a nitrogen path subsystem which are connected with the electric pile; the galvanic pile is used for outputting current through electrochemical reaction, the current acquisition module is used for acquiring the output current of the galvanic pile, the air path subsystem is used for providing air to the inside of the galvanic pile, the hydrogen path subsystem is used for providing hydrogen to the inside of the galvanic pile, and the nitrogen path subsystem is used for adjusting the concentration of air and hydrogen in the galvanic pile. And the controller is used for calculating the water content in the galvanic pile according to the galvanic pile output current and generating a regulation instruction so as to regulate and control the air path subsystem, the hydrogen path subsystem and the nitrogen path subsystem. According to the invention, the problems of insufficient water management, poor system reliability, low energy efficiency utilization rate and high system complexity of a fuel cell system in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system and a method for dynamically adjusting water content. Background Art

[0002] As a highly efficient, zero-emission energy conversion device, hydrogen fuel cells have garnered widespread attention in recent years in applications such as new energy vehicles, portable power generation equipment, and stationary power supplies. Proton exchange membrane fuel cells, with their advantages such as low operating temperature, fast startup, and high power density, have become a mainstream technology for commercial applications. However, the stable operation of fuel cell systems is highly dependent on precise control of their internal hydrothermal management.

[0003] During fuel cell operation, the cathode reaction continuously generates water. If the water production rate is too high and drainage is poor, liquid water can easily accumulate in the gas diffusion layer or flow field, blocking the gas channels and causing "flooding," which in turn limits air transmission and significantly reduces battery performance. Conversely, insufficient water production or excessive dehydration during operation can cause membrane electrolyte dehydration and "membrane drying," reducing proton conductivity, damaging the membrane structure, and impacting the stability and service life of the fuel cell.

[0004] Current fuel cell water management technology mainly relies on fixed strategies, such as adjusting the humidifier temperature and using condensers to remove excess water. It lacks dynamic feedback and closed-loop adjustment mechanisms on the actual water content of the battery. Therefore, when faced with different load conditions and changing environmental conditions, it cannot respond to changes in water production in a timely manner, resulting in problems such as insufficient water management and poor system reliability.

[0005] Furthermore, the gas exiting the fuel cell cathode carries a significant amount of waste heat. Directly discharging this heat would not only waste energy but also potentially cause thermal shock in the system, reducing overall energy efficiency. While some existing systems include preheating modules, these are often standalone heating devices that fail to effectively couple this with exhaust heat recovery, resulting in low energy efficiency and high system complexity. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a fuel cell system and a method for dynamically adjusting water content. The present invention solves the problems of insufficient water management, poor system reliability, low energy efficiency utilization, and high system complexity in the prior art fuel cell system.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A fuel cell system comprising:

[0009] Controller, fuel cell stack, and current acquisition module, air circuit subsystem, hydrogen circuit subsystem, and nitrogen circuit subsystem all connected to the fuel cell stack;

[0010] The controller is connected to the current acquisition module, the air path subsystem, the hydrogen path subsystem, and the nitrogen path subsystem respectively;

[0011] The fuel cell stack is used to output current through an electrochemical reaction, the current acquisition module is used to collect the output current of the fuel cell stack, the air path subsystem is used to provide air to the interior of the fuel cell stack, the hydrogen path subsystem is used to provide hydrogen to the interior of the fuel cell stack, and the nitrogen path subsystem is used to adjust the concentrations of air and hydrogen inside the fuel cell stack. The controller is used to calculate the water content inside the fuel cell stack based on the output current of the fuel cell stack and generate adjustment instructions to achieve regulation of the air path subsystem, hydrogen path subsystem, and nitrogen path subsystem.

[0012] Preferably, the air path subsystem comprises:

[0013] Air compressor, intercooler, first water flow sensor, heat exchanger and first tail valve;

[0014] The air compressor and the intercooler are connected in sequence, the intercooler is connected to the cathode inlet of the fuel cell stack, the first water flow sensor, the heat exchanger and the first tail valve are connected in sequence, and the first water flow sensor is connected to the cathode outlet of the fuel cell stack;

[0015] The air compressor is used to provide air, the intercooler is used to cool the air at the air compressor outlet, the first water flow sensor is used to monitor the water flow at the cathode outlet of the fuel cell stack, the heat exchanger is used to use the high-temperature gas at the cathode outlet of the fuel cell stack to heat the hydrogen at the anode inlet of the fuel cell stack, and the first tail exhaust valve is used to discharge unreacted oxygen and nitrogen and adjust the cathode cavity pressure of the fuel cell stack.

[0016] Preferably, the hydrogen circuit subsystem comprises:

[0017] Hydrogen cylinder, first-stage pressure reducing valve, second-stage pressure reducing valve, second water flow sensor, first three-way valve, second tail valve, hydrogen circulation pump and water-gas separator;

[0018] The hydrogen cylinder, the first-stage pressure reducing valve, the second-stage pressure reducing valve, and the cold-side inlet of the heat exchanger are connected in sequence; the cold-side outlet of the heat exchanger is connected to the anode inlet of the fuel cell stack; the second water flow sensor, the first three-way valve, and the second tail valve are connected in sequence; the second water flow sensor is connected to the anode outlet of the fuel cell stack; the first three-way valve is connected to the water-gas separator and the hydrogen circulation pump in sequence; and the hydrogen circulation pump is connected to the anode inlet of the fuel cell stack;

[0019] The hydrogen cylinder is used to provide hydrogen, the first-level pressure reducing valve and the second-level pressure reducing valve are used to gradually reduce the pressure of the hydrogen at the outlet of the hydrogen cylinder to a preset working pressure, the second water flow sensor is used to monitor the water flow at the outlet of the stack anode, the first three-way valve is used to control the direction of the gas at the outlet of the stack anode, the second tail exhaust valve is used to regularly discharge the water accumulated at the anode outlet and the nitrogen accumulated in the anode circulation, the hydrogen circulation pump is used to circulate the unreacted hydrogen at the stack anode back to the stack anode inlet, and the water-gas separator is used to separate liquid water from the stack anode tail gas.

[0020] Preferably, the nitrogen gas subsystem comprises:

[0021] Nitrogen cylinder, nitrogen pressure reducing valve and second three-way valve;

[0022] The nitrogen cylinder is connected to the nitrogen pressure reducing valve and the second three-way valve in sequence, and the second three-way valve is connected to the cathode inlet of the fuel cell stack and the outlet of the secondary pressure reducing valve respectively;

[0023] The nitrogen cylinder is used to provide high-pressure nitrogen, the nitrogen pressure reducing valve is used to reduce the high-pressure nitrogen at the outlet of the nitrogen cylinder to a preset safety pressure, and the second three-way valve is used to switch the nitrogen flow path.

[0024] Preferably, it also includes:

[0025] The thermal management subsystem is connected to the air path subsystem and the controller, and is used to cool the high-temperature air in the intercooler and absorb the excess heat generated during the operation of the fuel cell stack.

[0026] Preferably, the cooling method of the thermal management subsystem includes:

[0027] Air cooling and water cooling.

[0028] A method for dynamically adjusting water content, the method comprising:

[0029] Use the current acquisition module to collect the output current of the battery stack;

[0030] calculating a water generation amount based on the output current;

[0031] Use the water flow sensor to obtain the outlet water flow of the fuel cell stack;

[0032] Calculating the water content inside the fuel cell stack at the current moment according to the water generation amount and the outlet water flow rate;

[0033] The water content inside the fuel cell stack at the current moment is compared with a preset membrane dry threshold and a preset water flooding threshold, and corresponding adjustment instructions are generated to achieve regulation of the air path subsystem, hydrogen path subsystem, and nitrogen path subsystem.

[0034] The present invention discloses the following technical effects:

[0035] The present invention provides a fuel cell system and a method for dynamically regulating water content. The fuel cell system includes: a controller, a fuel cell stack, and a current acquisition module, an air path system, a hydrogen path system, and a nitrogen path system, all connected to the fuel cell stack; the controller is connected to the current acquisition module, the air path system, the hydrogen path system, and the nitrogen path system, respectively; the fuel cell stack is used to output current through an electrochemical reaction, the current acquisition module is used to acquire the output current of the fuel cell stack, the air path system is used to supply air to the interior of the fuel cell stack, the hydrogen path system is used to supply hydrogen to the interior of the fuel cell stack, and the nitrogen path system is used to adjust the concentrations of air and hydrogen inside the fuel cell stack; the controller is used to calculate the water content inside the fuel cell stack based on the fuel cell stack output current and generate adjustment instructions to achieve regulation of the air path system, the hydrogen path system, and the nitrogen path system. The present invention can combine real-time water production monitoring and water discharge measurement to achieve accurate estimation of internal water content, and adjust parameters such as inlet pressure, concentration, and flow rate accordingly to prevent water flooding and membrane drying, thereby improving system reliability and stability. The system's energy efficiency is improved by combining cathode outlet waste heat recovery with hydrogen preheating strategies. The system estimates the fuel cell's internal water content to determine its operating status and performs corresponding regulatory operations on both the anode and cathode sides, achieving more targeted control and higher precision. By regulating the water production rate through the nitrogen subsystem, the system maintains an appropriate water content within the fuel cell without the need for an external humidifier, simplifying the system structure and reducing fuel cell system operation and maintenance costs. A heat exchanger is added to the existing air and hydrogen system circuits, resulting in minimal changes and easy implementation. Furthermore, the high-temperature gas at the fuel cell's cathode outlet is used to preheat the hydrogen at the anode inlet, recovering and reusing waste heat, thereby improving the fuel cell's overall energy efficiency. This improves the fuel cell's cold start performance during cold starts. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A schematic diagram of the structure of a fuel cell system provided by an embodiment of the present invention;

[0038] Figure 2 A detailed schematic diagram of a fuel cell system device provided in an embodiment of the present invention.

[0039] Reference numerals:

[0040] 1. Air flow; 2. Air compressor; 3. Intercooler; 4. First water flow sensor; 5. Heat exchanger; 6. First tail exhaust valve; 7. Hydrogen cylinder; 8. First stage pressure reducing valve; 9. Second stage pressure reducing valve; 10. Second water flow sensor; 11. First three-way valve; 12. Second tail exhaust valve; 13. Water-gas separator; 14. Hydrogen circulation pump; 15. Fuel cell; 16. Second three-way valve; 17. Nitrogen pressure reducing valve; 18. Nitrogen cylinder; 19. Current acquisition module; 20. Controller; 21. Air circuit system; 22. Hydrogen circuit system; 23. Nitrogen circuit system. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 1 As shown, the present invention provides a fuel cell system, comprising:

[0044] Controller 20, fuel cell stack 15 and current acquisition module 19, air path subsystem 21, hydrogen path subsystem 22, nitrogen path subsystem 23, all connected to fuel cell stack 15;

[0045] The controller 20 is connected to the current acquisition module 19, the air circuit subsystem 21, the hydrogen circuit subsystem 22, and the nitrogen circuit subsystem 23 respectively;

[0046] The fuel cell stack 15 is used to output electrical energy through electrochemical reactions, the current acquisition module 19 is used to collect the output current of the fuel cell stack 15, the air subsystem 21 is used to provide air to the interior of the fuel cell stack 15, the hydrogen subsystem 22 is used to provide hydrogen to the interior of the fuel cell stack 15, and the nitrogen subsystem 23 is used to adjust the concentrations of air and hydrogen inside the fuel cell stack 15. The controller 20 is used to calculate the water content inside the fuel cell stack 15 based on the output current of the fuel cell stack 15 and generate adjustment instructions to achieve regulation of the air subsystem 21, the hydrogen subsystem 22, and the nitrogen subsystem 23.

[0047] Specifically, such as Figure 2As shown, the fuel cell stack 15 is an energy conversion device that outputs electrical energy through electrochemical reactions within the fuel cell stack 15. The current acquisition module 19 acquires the output current through a current sensor module (such as a Hall current sensor) connected to the fuel cell stack 15.

[0048] Furthermore, the air path subsystem 21 includes:

[0049] Air compressor 2, intercooler 3, first water flow sensor 4, heat exchanger 5, first tail valve 6;

[0050] The air compressor 2 and the intercooler 3 are connected in sequence, the intercooler 3 is connected to the cathode inlet of the fuel cell stack 15, the first water flow sensor 4, the heat exchanger 5, and the first tail valve 6 are connected in sequence, and the first water flow sensor 4 is connected to the cathode outlet of the fuel cell stack 15;

[0051] The air compressor 2 is used to provide air according to the input air flow 1, the intercooler 3 is used to cool the air at the outlet of the air compressor 2, the first water flow sensor 4 is used to monitor the water flow at the cathode outlet of the fuel cell stack 15, the heat exchanger 5 is used to heat the hydrogen at the anode inlet with the high-temperature gas at the cathode outlet of the fuel cell stack 15, and the first tail valve 6 is used to exhaust and drain water, discharge unreacted oxygen and nitrogen, maintain the stability of the cathode gas concentration and pressure, regularly discharge produced water, prevent water accumulation and flooding at the cathode, and ensure the performance of the fuel cell stack 15; adjust the pressure, and work together with the air compressor 2 to adjust the cathode cavity pressure to improve the system response and stability; safety protection, as a pressure relief channel, prevent excessive pressure from damaging the fuel cell stack 15 under abnormal working conditions.

[0052] Specifically, the air compressor 2 and intercooler 3 in the air circuit subsystem 21 are connected in sequence to the cathode inlet of the fuel cell; the first water flow sensor 4, the hot side inlet of the heat exchanger 5, and the hot side outlet of the heat exchanger 5 are connected in sequence to the first tail valve 6 and connected to the cathode outlet of the fuel cell. The air circuit subsystem 21 is used to supply the oxygen required for the electrochemical reaction to occur. The air compressor 2 provides air of appropriate pressure and flow to the fuel cell system. The intercooler 3 cools the high-temperature gas at the outlet of the air compressor 2 to prevent the high-temperature gas from directly entering the interior of the fuel cell and affecting the performance of the stack 15 and the proton exchange membrane. The heat exchanger 5 is used to use the high-temperature gas at the cathode outlet of the fuel cell to heat the hydrogen at the anode inlet, thereby increasing the reaction rate, recovering waste heat, and improving energy utilization. During the cold start process, the cold start performance of the fuel cell can be improved.

[0053] Furthermore, the hydrogen circuit subsystem 22 includes:

[0054] Hydrogen cylinder 7, first-stage pressure reducing valve 8, second-stage pressure reducing valve 9, second water flow sensor 10, first three-way valve 11, second tail valve 12, hydrogen circulation pump 14, water-gas separator 13;

[0055] The hydrogen cylinder 7, the first-stage pressure reducing valve 8, the second-stage pressure reducing valve 9, and the cold-side inlet of the heat exchanger 5 are connected in sequence, the cold-side outlet of the heat exchanger 5 is connected to the anode inlet of the fuel cell stack 15, the second water flow sensor 10, the first three-way valve 11, and the second tail valve 12 are connected in sequence, the second water flow sensor 10 is connected to the anode outlet of the fuel cell stack 15, the first three-way valve 11 is connected to the water separator 13 and the hydrogen circulation pump 14 in sequence, and the hydrogen circulation pump 14 is connected to the anode inlet of the fuel cell stack 15;

[0056] Hydrogen cylinder 7, first-stage pressure reducing valve 8, second-stage pressure reducing valve 9, second water flow sensor 10, first three-way valve 11, second tail valve 12, hydrogen circulation pump 14, water-gas separator 13;

[0057] The hydrogen cylinder 7 is used to provide high-pressure hydrogen. The first-level pressure reducing valve 8 and the second-level pressure reducing valve 9 are respectively used to gradually reduce the pressure of the high-pressure hydrogen at the outlet of the hydrogen cylinder 7 to a working pressure suitable for the anode gas supply of the fuel cell stack 15. The second water flow sensor 10 is used to monitor the water flow at the anode outlet of the fuel cell stack 15. The first three-way valve 11 is used to control the direction of the anode outlet gas and switch to a circulation or discharge channel. The first three-way valve 11 connects the water-gas separator 13 and the hydrogen circulation pump 14 as a circulation channel. The first three-way valve 11 connects the second tail drain valve 12 as a discharge channel. The second tail drain valve 12 is used to regularly discharge the water accumulated at the anode outlet and the nitrogen accumulated in the anode circulation to maintain the anode side pressure and gas purity and ensure the reaction stability. The hydrogen circulation pump 14 is used to circulate the unreacted hydrogen at the anode back to the anode inlet of the fuel cell stack 15 to improve the hydrogen utilization rate and play the role of intake humidification. The water-gas separator 13 is used to separate liquid water in the anode tail gas, assist in water management, and avoid anode flooding.

[0058] Specifically, the hydrogen gas circuit subsystem 22 includes a hydrogen cylinder 7, a first pressure reducing valve 8, a second pressure reducing valve 9, a cold-side inlet of a heat exchanger 5, and a cold-side outlet of the heat exchanger 5, which are sequentially connected to the anode inlet of the fuel cell. A second water flow sensor 10, a first three-way valve 11, and a second tail valve 12 are sequentially connected to the anode outlet of the fuel cell. One outlet of the first three-way valve 11 is sequentially connected to a water separator 13 and a hydrogen circulation pump 14, which are connected in parallel to the anode inlet of the fuel cell. The hydrogen gas, which is depressurized by the second pressure reducing valve 9 in the hydrogen circuit subsystem 22, is used to provide hydrogen gas at an appropriate pressure to the fuel cell stack 15 to ensure the continued electrochemical reaction. The water separator 13 is used to separate liquid water and gas at the anode outlet, which can improve drainage efficiency and prevent water from returning to the fuel cell stack 15 with the gas, thereby achieving more effective water management. The hydrogen circulation pump 14 not only improves hydrogen utilization, but also serves as an intake air humidifier, improving the output performance of the fuel cell stack 15.

[0059] Furthermore, the nitrogen gas subsystem 23 includes:

[0060] Nitrogen cylinder 18, nitrogen pressure reducing valve 17 and second three-way valve 16;

[0061] The nitrogen cylinder 18 is connected to the nitrogen pressure reducing valve 17 and the second three-way valve 16 in sequence. The second three-way valve 16 is connected to the cathode inlet of the fuel cell stack 15 and the outlet of the secondary pressure reducing valve 9 respectively.

[0062] The nitrogen cylinder 18 is used to provide nitrogen, and the nitrogen pressure reducing valve 17 is used to reduce the high-pressure nitrogen at the outlet of the nitrogen cylinder 18 to a safe pressure suitable for the operation of the system pipeline and the fuel cell stack 15. The second three-way valve 16 is used to switch the nitrogen flow path, which can not only realize the directional purge of the cathode or anode channel, but also realize the adjustment of the concentration and flow of the reaction gas in the cathode or anode channel, thereby controlling the water production rate.

[0063] Specifically, the nitrogen cylinder 18 in the nitrogen gas subsystem 23 is sequentially connected to the nitrogen pressure reducing valve 17 and the second three-way valve 16. One outlet of the second three-way valve 16 is connected in parallel to the cathode inlet of the fuel cell, and the other outlet of the second three-way valve 16 is connected in parallel to the outlet of the secondary pressure reducing valve 9 of the hydrogen gas subsystem 22. In addition to purging the anode and cathode after the fuel cell stack 15 is shut down, the nitrogen gas subsystem 23 can also regulate the concentration and flow of the anode and cathode reactant gases, thereby controlling the water production rate, increasing the purge gas flow rate, and effectively regulating the water content within the fuel cell.

[0064] Furthermore, it also includes:

[0065] The thermal management subsystem is connected to the air path subsystem 21 and the controller 20, and is used to cool the high-temperature air in the intercooler 3 and take away the excess heat generated during the operation of the fuel cell stack 15, so as to ensure that the fuel cell stack 15 operates at a suitable temperature.

[0066] Specifically, fuel cells release a large amount of heat during electrochemical reactions. If this heat is not removed promptly, the temperature inside the fuel cell stack 15 will rise, and the water content in the membrane will change, which will in turn affect the performance of the fuel cell. The role of the thermal management subsystem is to promptly remove this heat. Whether using air cooling or water cooling, the thermal management subsystem is responsible for cooling the high-temperature air in the intercooler 3 and removing excess heat generated during the operation of the fuel cell stack 15, thereby maintaining the fuel cell operating at an appropriate temperature.

[0067] Furthermore, the controller 20 is used to receive real-time operating data collected by the current acquisition module 19, water flow sensor, etc. in the fuel cell system, estimate the water generation and water content based on the built-in algorithm, and intelligently judge the current operating state according to the set water threshold value, output adjustment instructions to control parameters such as intake pressure, gas flow and concentration, and the air subsystem 21, hydrogen subsystem 22, and nitrogen subsystem 23 components execute corresponding adjustment programs to form a closed-loop water management control strategy to ensure that the stack 15 operates stably under the appropriate water content state. At the same time, the controller 20 is also responsible for adjusting the thermal management subsystem components to ensure that the stack 15 operates at an appropriate temperature. The air subsystem 21, hydrogen subsystem 22, nitrogen subsystem 23, and thermal management subsystem are electrically connected to the controller 20.

[0068] This embodiment also provides a method for dynamically adjusting water content, the method comprising:

[0069] Use the current acquisition module to collect the output current of the battery stack;

[0070] calculating a water generation amount based on the output current;

[0071] Use the water flow sensor to obtain the outlet water flow of the fuel cell stack;

[0072] Calculating the water content inside the fuel cell stack at the current moment according to the water generation amount and the outlet water flow rate;

[0073] The water content inside the fuel cell stack at the current moment is compared with a preset membrane dry threshold and a preset water flooding threshold, and corresponding adjustment instructions are generated to achieve regulation of the air path subsystem, hydrogen path subsystem, and nitrogen path subsystem.

[0074] Specifically, by collecting the output current of the fuel cell stack and monitoring the water production and discharge in real time, the water content inside the fuel cell is accurately estimated and compared with the flooding threshold and membrane dryness threshold. When the water content is greater than the flooding threshold, it indicates that the water content inside the fuel cell is too high and is in a flooded state. When the water content is less than the membrane dryness threshold, it indicates that the water content inside the fuel cell is too low and is in a membrane dryness state.

[0075] When the fuel cell is flooded, the anode and cathode inlet pressures are increased to enhance scavenging capacity and accelerate water removal. Simultaneously, the second three-way valve is opened to introduce nitrogen into the air and hydrogen subsystems, increasing the scavenging flow rate and further accelerating water removal. An appropriate amount of nitrogen is added to the cathode air to reduce the oxygen concentration, and a hydrogen-nitrogen mixture is introduced into the anode to reduce the hydrogen concentration entering the stack, slowing the reaction rate and further slowing water generation. The outlet of the first three-way valve connecting to the water separator is closed, and the hydrogen circulation pump is turned off. Hydrogen circulation humidification is discontinued to prevent moisture in the circulating hydrogen from entering the fuel cell stack.

[0076] When the fuel cell is in a dry membrane state, the anode and cathode inlet pressures are reduced, reducing the scavenging capacity to prevent excessive water carryover. At the same time, the inflow of hydrogen and oxygen is increased to improve the electrochemical reaction rate and promote water generation within the fuel cell. At the same time, the speed of the hydrogen circulation pump is increased to increase the amount of circulating hydrogen and humidify the anode inlet gas.

[0077] When the fuel cell is in a normal working state, the second three-way valve remains closed.

[0078] When the controller receives a shutdown command, the fuel cell needs to enter the shutdown state, the second three-way valve remains open, and nitrogen is purged into the anode and cathode channels, mainly to remove residual gas and accumulated water to prevent damage and aging of the fuel cell.

[0079] More specifically, water generation estimates:

[0080] During the operation of the fuel cell, the output current I of the stack is collected in real time. st , the water production per unit time can be estimated by the following formula:

[0081] ;

[0082] Where, I st Represents the stack current; n represents the number of single cells in the stack; M w represents the molar mass of water; F is the Faraday constant.

[0083] Outlet water flow monitoring:

[0084] Water flow sensors are placed at the cathode outlet and the anode outlet respectively to record the amount of water discharged per unit time W w,out .

[0085] Water content estimation:

[0086] According to the difference between water production and water discharge, estimate the water content inside the battery at the current moment:

[0087] ;

[0088] And compare it with the set flooding threshold and membrane drying threshold.

[0089] Feedback regulation strategy:

[0090] When the water content is greater than the flooding threshold, the anode and cathode air inlet pressures are increased to enhance the scavenging capacity and accelerate the discharge of water;

[0091] A mixture of hydrogen and nitrogen is fed to the anode to reduce hydrogen concentration and thus the reaction rate. A suitable amount of nitrogen is added to the cathode air to reduce oxygen concentration, further slowing water formation and increasing the purge air flow rate to further accelerate water removal. Simultaneously, the outlet of the first three-way valve connecting to the water separator is closed, and the hydrogen circulation pump is turned off, discontinuing hydrogen circulation humidification to prevent moisture in the circulating hydrogen from entering the fuel cell stack.

[0092] When the water content falls below the membrane dry threshold, the inlet pressure is lowered, reducing the scavenging capacity to prevent rapid water removal. The inflow of hydrogen and oxygen is increased to boost the electrochemical reaction rate and promote water generation within the fuel cell. Simultaneously, the speed of the hydrogen circulation pump is increased to increase the circulating hydrogen volume and humidify the anode inlet gas.

[0093] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0094] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A fuel cell system, characterized in that: include: Controller, fuel cell stack, and current acquisition module, air circuit subsystem, hydrogen circuit subsystem, and nitrogen circuit subsystem all connected to the fuel cell stack; The controller is connected to the current acquisition module, the air path subsystem, the hydrogen path subsystem, and the nitrogen path subsystem respectively; The fuel cell stack is used to output current through an electrochemical reaction, the current acquisition module is used to collect the output current of the fuel cell stack, the air path subsystem is used to provide air to the interior of the fuel cell stack, the hydrogen path subsystem is used to provide hydrogen to the interior of the fuel cell stack, and the nitrogen path subsystem is used to adjust the concentrations of air and hydrogen inside the fuel cell stack. The controller is used to calculate the water content inside the fuel cell stack based on the output current of the fuel cell stack and generate adjustment instructions to achieve regulation of the air path subsystem, hydrogen path subsystem, and nitrogen path subsystem.

2. A fuel cell system according to claim 1, characterized in that: The air path subsystem includes: Air compressor, intercooler, first water flow sensor, heat exchanger and first tail valve; The air compressor and the intercooler are connected in sequence, the intercooler is connected to the cathode inlet of the fuel cell stack, the first water flow sensor, the heat exchanger and the first tail valve are connected in sequence, and the first water flow sensor is connected to the cathode outlet of the fuel cell stack; The air compressor is used to provide air, the intercooler is used to cool the air at the air compressor outlet, the first water flow sensor is used to monitor the water flow at the cathode outlet of the fuel cell stack, the heat exchanger is used to use the high-temperature gas at the cathode outlet of the fuel cell stack to heat the hydrogen at the anode inlet of the fuel cell stack, and the first tail exhaust valve is used to discharge unreacted oxygen and nitrogen and adjust the cathode cavity pressure of the fuel cell stack.

3. A fuel cell system according to claim 2, characterized in that: The hydrogen circuit subsystem comprises: Hydrogen cylinder, first-stage pressure reducing valve, second-stage pressure reducing valve, second water flow sensor, first three-way valve, second tail valve, hydrogen circulation pump and water-gas separator; The hydrogen cylinder, the first-stage pressure reducing valve, the second-stage pressure reducing valve, and the cold-side inlet of the heat exchanger are connected in sequence; the cold-side outlet of the heat exchanger is connected to the anode inlet of the fuel cell stack; the second water flow sensor, the first three-way valve, and the second tail valve are connected in sequence; the second water flow sensor is connected to the anode outlet of the fuel cell stack; the first three-way valve is connected to the water-gas separator and the hydrogen circulation pump in sequence; and the hydrogen circulation pump is connected to the anode inlet of the fuel cell stack; The hydrogen cylinder is used to provide hydrogen, the first-level pressure reducing valve and the second-level pressure reducing valve are used to gradually reduce the pressure of the hydrogen at the outlet of the hydrogen cylinder to a preset working pressure, the second water flow sensor is used to monitor the water flow at the outlet of the stack anode, the first three-way valve is used to control the direction of the gas at the outlet of the stack anode, the second tail exhaust valve is used to regularly discharge the water accumulated at the anode outlet and the nitrogen accumulated in the anode circulation, the hydrogen circulation pump is used to circulate the unreacted hydrogen at the stack anode back to the stack anode inlet, and the water-gas separator is used to separate liquid water from the stack anode tail gas.

4. A fuel cell system according to claim 3, characterized in that: The nitrogen circuit subsystem comprises: Nitrogen cylinder, nitrogen pressure reducing valve and second three-way valve; The nitrogen cylinder is connected to the nitrogen pressure reducing valve and the second three-way valve in sequence, and the second three-way valve is connected to the cathode inlet of the fuel cell stack and the outlet of the secondary pressure reducing valve respectively; The nitrogen cylinder is used to provide high-pressure nitrogen, the nitrogen pressure reducing valve is used to reduce the high-pressure nitrogen at the outlet of the nitrogen cylinder to a preset safety pressure, and the second three-way valve is used to switch the nitrogen flow path.

5. A fuel cell system according to claim 2, characterized in that: Also includes: The thermal management subsystem is connected to the air path subsystem and the controller, and is used to cool the high-temperature air in the intercooler and absorb the excess heat generated during the operation of the fuel cell stack.

6. A fuel cell system according to claim 5, characterized in that: The cooling method of the thermal management subsystem includes: Air cooling and water cooling.

7. A method for dynamically adjusting water content, applied to the fuel cell system according to any one of claims 1 to 6, characterized in that: The adjustment method comprises: Use the current acquisition module to collect the output current of the battery stack; calculating a water generation amount based on the output current; Use the water flow sensor to obtain the outlet water flow of the fuel cell stack; Calculating the water content inside the fuel cell stack at the current moment according to the water generation amount and the outlet water flow rate; The water content inside the fuel cell stack at the current moment is compared with a preset membrane dry threshold and a preset water flooding threshold, and corresponding adjustment instructions are generated to achieve regulation of the air path subsystem, hydrogen path subsystem, and nitrogen path subsystem.

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