Water management control method and device of fuel cell stack system, storage medium and vehicle

Abstract

The invention discloses a water management control method and device of a fuel cell stack system, a storage medium and a vehicle, a fuel cell stack comprises a plurality of single cells, and each single cell comprises an anode and a cathode. The method comprises the following steps: acquiring an internal water flow parameter of internal water molecule movement of a fuel cell stack and an external water flow parameter of external water molecule movement; determining the actual dragging water flow of water molecules flowing from the anode to the cathode under the action of the electroosmosis force based on the internal water flow parameter and the external water flow parameter; determining the self-humidifying state of the fuel cell stack based on the actual dragging water flow, the target dragging water flow and the voltage value of each single cell; an operating parameter of the fuel cell stack is adjusted based on the self-humidifying state. According to the method, the weight and the size of the fuel cell stack system can be reduced, the difficulty of mechanical arrangement is reduced, the mechanical integration efficiency is improved, the cost is relatively low, and self-humidification and water management are controllable, so that the operation reliability and the operation efficiency are improved.

Description

Technical Field

[0001] The present application relates to the technical field of fuel cell stacks, and particularly relates to a water management control method for a fuel cell stack system, a water management control device for a fuel cell stack system, a computer-readable storage medium, and a vehicle. Background Art

[0002] A fuel cell is a zero-emission green energy solution. Since a fuel cell burns hydrogen and the only product is pure water generated at the cathode, which is mainly discharged from the stack through cathode purge. Water is not only a product of the fuel cell, but also plays an important role in moistening the membrane electrode inside the fuel cell, helping hydrogen protons pass through the MEA, reducing mass transfer losses, and increasing the power generation efficiency of the fuel cell. If there is too much liquid water inside the stack, it will cause flooding of the membrane electrode, hindering the reactants from reaching the catalyst layer. If there is too little liquid water, the membrane electrode will be too dry, increasing the mass transfer loss of hydrogen protons and resulting in poor power generation performance of the stack. Therefore, managing the moisture inside the stack is a very important task for a fuel cell engine.

[0003] Currently, most fuel cells adopt the method of external humidification, that is, the gaseous water and liquid water discharged from the cathode outlet of the fuel cell reach the wet side of the external membrane humidifier, and the moisture penetrates through the humidification membrane tube wall of the external humidifier to the dry side to humidify the dry air, and the dry air enters the stack after humidification. In this way, it completely relies on the passive humidification of the humidifier, and the humidification process is uncontrollable. In addition, the weight and volume of the required humidifier increase sharply with the increase of the fuel cell power, resulting in a heavy and large fuel cell system, greatly reducing the power density and volume density of the fuel cell system. Summary of the Invention

[0004] The present application aims to at least solve one of the technical problems in the related art to some extent. For this purpose, the first object of the present application is to propose a water management control method for a fuel cell stack system, which obtains the internal water flow parameters of the movement of water molecules inside the fuel cell stack and the external water flow parameters of the movement of water molecules outside, determines the actual water drag flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters, determines the self-humidification state of the fuel cell stack based on the actual water drag flow rate, the target water drag flow rate, and the voltage value of each single cell, and adjusts the operating parameters of the fuel cell stack based on the self-humidification state. Thus, without an external humidifier, it can reduce the weight and volume of the fuel cell stack system, reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, have a lower cost, and the self-humidification and water management are controllable, thereby increasing the operating reliability and operating efficiency.

[0005] The second object of the present application is to propose a water management control device for a fuel cell stack system.

[0006] The third object of the present application is to provide a computer-readable storage medium.

[0007] The fourth object of the present application is to provide a vehicle.

[0008] To achieve the above object, an embodiment of the first aspect of the present application provides a water management control method for a fuel cell stack system. The fuel cell stack includes a plurality of single cells, and each single cell includes an anode and a cathode. The method includes: obtaining an internal water flow parameter of the movement of water molecules inside the fuel cell stack and an external water flow parameter of the movement of water molecules outside the fuel cell stack; determining an actual water drag flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameter and the external water flow parameter; determining the self-humidifying state of the fuel cell stack based on the actual water drag flow rate, a target water drag flow rate, and the voltage value of each single cell; and adjusting the operating parameters of the fuel cell stack based on the self-humidifying state.

[0009] According to the water management control method of the fuel cell stack system in the embodiment of the present application, an internal water flow parameter of the movement of water molecules inside the fuel cell stack and an external water flow parameter of the movement of water molecules outside the fuel cell stack are obtained, an actual water drag flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force is determined based on the internal water flow parameter and the external water flow parameter, the self-humidifying state of the fuel cell stack is determined based on the actual water drag flow rate, a target water drag flow rate, and the voltage value of each single cell, and the operating parameters of the fuel cell stack are adjusted based on the self-humidifying state. Thus, the method does not require an external humidifier, can reduce the weight and volume of the fuel cell stack system, and reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, has a lower cost, and the self-humidifying and water management are controllable, thereby increasing the operating reliability and operating efficiency.

[0010] In addition, the water management control method of the fuel cell stack system according to the above embodiment of the present application may further have the following additional technical features:

[0011] According to an embodiment of the present application, determining the self-humidification state of the fuel cell stack based on the actual dragged water flow rate, the target dragged water flow rate, and the voltage value of each single cell includes: when the actual dragged water flow rate is greater than or equal to the target dragged water flow rate and less than the target dragged water flow rate plus a preset flow rate threshold, or when the average voltage of all single cells is greater than a preset average voltage threshold and the standard deviation of the voltages of all single cells is less than a preset standard deviation threshold, determining the self-humidification state of the fuel cell stack as the first self-humidification state, where the first self-humidification state indicates that the actual dragged water flow rate is within a preset water flow rate range; when the actual dragged water flow rate is greater than or equal to the dragged water flow rate plus the preset flow rate threshold and there is a single cell with a voltage value lower than the preset voltage threshold, or when the actual dragged water flow rate is greater than or equal to the dragged water flow rate plus the preset flow rate threshold and the standard deviation of the voltages of all single cells is less than the preset standard deviation threshold, determining the self-humidification state of the fuel cell stack as the second self-humidification state, where the second self-humidification state indicates that the actual dragged water flow rate exceeds the preset water flow rate range; when the actual dragged water flow rate is less than the target dragged water flow rate and the average voltage of all single cells is less than the preset average voltage threshold, or when the actual dragged water flow rate is less than the target dragged water flow rate and the standard deviation of the voltages of all single cells is greater than the preset standard deviation threshold, or when the actual dragged water flow rate is less than the target dragged water flow rate and there is a single cell with a voltage value lower than the preset voltage threshold, determining the self-humidification state of the fuel cell stack as the third self-humidification state, where the third self-humidification state indicates that the actual dragged water flow rate is less than the preset water flow rate range.

[0012] According to an embodiment of the present application, the operating parameters of the fuel cell stack include at least one of the cathode pressure and the anode pressure, the rotation speed of the circulation water pump, the opening duration of the anode drain valve, the cathode purge volume, and the cathode stoichiometry ratio. Adjusting the operating parameters of the fuel cell stack based on the self-humidification state includes: when the self-humidification state is the first self-humidification state, keeping the operating parameters unchanged; when the self-humidification state is the second self-humidification state, controlling at least one of the cathode pressure to be greater than the anode pressure, reducing the rotation speed, increasing the opening duration, increasing the cathode purge flow rate, and increasing the cathode stoichiometry ratio; when the self-humidification state is the third self-humidification state, controlling at least one of the cathode pressure to be less than the anode pressure, increasing the rotation speed, reducing the opening duration, reducing the cathode purge flow rate, and reducing the cathode stoichiometry ratio.

[0013] According to an embodiment of the present application, the internal water flow parameters include: the liquid water flow rate and the gaseous water flow rate of water molecules moving from the cathode to the anode under the action of concentration difference diffusion, and the pressure difference diffusion water flow rate of water molecules moving from the cathode to the anode under the action of pressure difference. The external water flow parameters include: the drainage volume of the anode and the water circulation flow rate of the anode. Determining the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters includes: subtracting the pressure difference diffusion water flow rate and the anode drainage volume from the sum of the liquid water flow rate, the gaseous water flow rate, the anode water circulation flow rate, and a preset flow rate threshold to obtain the actual drag water flow rate.

[0014] According to an embodiment of the present application, obtaining the gaseous water flow rate includes: obtaining the cathode humidity, anode humidity, cathode pressure, anode pressure, cathode saturation vapor pressure, and anode saturation vapor pressure of the fuel cell stack; multiplying the result of subtracting the ratio of the product of the anode saturation vapor pressure and the anode humidity to the anode pressure from the ratio of the product of the cathode saturation vapor pressure and the cathode humidity to the cathode pressure by the gaseous water diffusion coefficient to obtain the obtained gaseous water flow rate; obtaining the pressure difference diffusion water flow rate includes: determining the pressure difference diffusion water flow rate based on the product of the pressure difference between the anode pressure and the cathode pressure and the water permeation resistance coefficient of the membrane electrode. Wherein, when the pressure difference is greater than zero, the water permeation resistance coefficient of the membrane electrode is positive, and when the force difference is less than zero, the water permeation resistance coefficient of the membrane electrode is negative; obtaining the anode drainage volume includes: determining the anode drainage volume based on the stack current and a first preset correspondence; the external water flow parameters further include the cathode drainage volume. Obtaining the cathode drainage volume includes: using the result of subtracting the anode drainage volume from the ratio of the product of the number of single cells and the stack current to a preset constant as the obtained cathode drainage volume; obtaining the anode water circulation flow rate includes: determining the anode mixed gas return flow rate based on the rotation speed of the circulation pump and a second preset correspondence; determining the anode water circulation flow rate based on the product of the anode mixed gas return flow rate and the concentration coefficient of gaseous water and liquid water mist in the circulation flow rate; obtaining the target drag water flow rate includes: determining the target drag water flow rate based on a preset constant and the product of the stack current and the number of single cells.

[0015] According to an embodiment of the present application, obtaining the liquid water flow rate includes: obtaining the cathode stoichiometry of the fuel cell stack; determining the liquid water flow rate based on the stack current, the number of single cells, the cathode stoichiometry, the cathode humidity, the cathode pressure, the cathode saturation vapor pressure, the gaseous water flow rate, the target drag water flow rate, the cathode drainage volume, and the anode drainage volume.

[0016] According to an embodiment of the present application, the liquid water flow rate is determined by the following formula:

[0017]

[0018] where f 1 is the liquid water flow rate, k 1 is the liquid water diffusion coefficient, I is the stack current, N is the number of single cells, λ represents the cathode stoichiometry, P c is the cathode pressure, RH c is the cathode humidity, T c is the cathode saturation vapor pressure, f 2 is the gaseous water flow rate, f 3 is the target drag water flow rate, f 4 is the cathode drainage flow rate, f 5 is the anode drainage flow rate.

[0019] To achieve the above object, an embodiment of the second aspect of the present application provides a water management control device for a fuel cell stack system. The fuel cell stack includes a plurality of single cells, and each single cell includes an anode and a cathode. The device includes: an acquisition module for acquiring internal water flow parameters of the movement of water molecules inside the fuel cell stack and external water flow parameters of the movement of water molecules outside; a first determination module for determining an actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters; a second determination module for determining the self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell; and an adjustment module for adjusting the operating parameters of the fuel cell stack based on the self-humidification state.

[0020] For the water management control device of the fuel cell stack system according to the embodiment of the present application, the acquisition module is used to acquire internal water flow parameters of the movement of water molecules inside the fuel cell stack and external water flow parameters of the movement of water molecules outside. The first determination module is used to determine an actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters. The second determination module is used to determine the self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell. The adjustment module is used to adjust the operating parameters of the fuel cell stack based on the self-humidification state. Thus, the device does not require an external humidifier, can reduce the weight and volume of the fuel cell stack system, and reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, has a lower cost, and the self-humidification and water management are controllable, thereby increasing the operating reliability and operating efficiency.

[0021] To achieve the above object, an embodiment of the third aspect of the present application provides a computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, the water management control method of the fuel cell stack system described above is implemented.

[0022] According to the computer-readable storage medium of the embodiment of the present application, by implementing the water management control method of the fuel cell stack system described above when executed, without an external humidifier, it is possible to reduce the weight and volume of the fuel cell stack system, reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, have a lower cost, and the self-humidification and water management are controllable, thereby increasing the operation reliability and operation efficiency.

[0023] To achieve the above object, a vehicle proposed by an embodiment of the fourth aspect of the present application includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the water management control method of the fuel cell stack system described above is implemented.

[0024] According to the vehicle of the embodiment of the present application, by implementing the water management control method of the fuel cell stack system described above, without an external humidifier, it is possible to reduce the weight and volume of the fuel cell stack system, reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, have a lower cost, and the self-humidification and water management are controllable, thereby increasing the operation reliability and operation efficiency.

[0025] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0026] Figure 1 It is a flowchart of the water management control method of the fuel cell stack system according to an embodiment of the present application;

[0027] Figure 2 It is a flowchart of the water management control method of the fuel cell stack system according to a specific example of the present application;

[0028] Figure 3 It is a block schematic diagram of the water management control device of the fuel cell stack system according to an embodiment of the present application;

[0029] Figure 4 It is a block schematic diagram of the vehicle according to an embodiment of the present application. Detailed Embodiments

[0030] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application.

[0031] The following describes a water management control method for a fuel cell stack system, a water management control device for a fuel cell stack system, a computer-readable storage medium, and a vehicle proposed in an embodiment of the present application with reference to the accompanying drawings.

[0032] Figure 1 It is a flowchart of a water management control method for a fuel cell stack system according to an embodiment of the present application.

[0033] As Figure 1 shown, the water management control method for a fuel cell stack system according to an embodiment of the present application may include the following steps:

[0034] S1, Obtain internal water flow parameters of the movement of water molecules inside the fuel cell stack and external water flow parameters of the movement of water molecules outside.

[0035] S2, Based on the internal water flow parameters and the external water flow parameters, determine the actual water drag flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force.

[0036] S3, Based on the actual water drag flow rate, the target water drag flow rate, and the voltage value of each single cell, determine the self-humidification state of the fuel cell stack.

[0037] S4, Adjust the operating parameters of the fuel cell stack based on the self-humidification state.

[0038] Specifically, the fuel cell stack may include a plurality of single cells, each single cell includes an anode and a cathode, and in the management of the fuel cell stack, it is crucial to understand and control the internal and external water flow parameters to maintain the performance of the stack and extend its life. First, the internal water flow parameters of the movement of water molecules inside the fuel cell stack and the external water flow parameters of the movement of water molecules outside can be obtained. The internal water flow parameters mainly involve the movement of water molecules inside the stack, such as the flow rate of liquid water moving from the cathode to the anode due to concentration difference diffusion, the flow rate of gaseous water molecules moving from the cathode to the anode due to concentration difference diffusion, the flow rate of water molecules moving from the high-pressure area to the low-pressure area due to the pressure difference between the anode and the cathode, and the flow rate of water molecules dragged from the anode to the cathode when protons pass through the membrane during the electrochemical reaction, etc. The external water flow parameters mainly involve the movement of water molecules outside the stack, such as the flow rate of liquid water discharged from the anode of the single cell, which is removed through the drainage system, or the flow rate of water that enters the stack again after being treated after being discharged from the anode, etc.

[0039] When obtaining the above internal water flow parameters and external water flow parameters, sensors can be used to measure the key operating parameters of the stack in real time, such as temperature, pressure, humidity, and flow rate, and collect data during the operation of the stack, including current, voltage, and gas flow rate, etc. Physical and chemical models are used to calculate the internal water flow parameters, such as calculating the gaseous water flow rate according to Fick's law of diffusion. After determining the internal water flow parameters and external water flow parameters, the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force can be determined according to the internal water flow parameters and external water flow parameters. That is, in a fuel cell stack, the actual drag water flow rate under the action of electroosmotic force refers to the flow rate of water molecules dragged from the anode to the cathode when protons pass through the membrane during the electrochemical reaction process. This flow rate is crucial for maintaining the water balance inside the stack. For example, the opening degree can be determined through a pre-set corresponding relationship. For example, the relationship between the internal water flow parameters, external water flow parameters, and the actual drag water flow rate is determined in advance. After the internal water flow parameters and external water flow parameters are determined, the actual drag water flow rate can be obtained directly by calling the corresponding relationship.

[0040] After obtaining the actual drag water flow rate, the self-humidification state of the fuel cell stack can be determined according to the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell. For example, a voltage threshold can be set. For example, if the voltage of any single cell is lower than 2.0, it is considered that there may be a problem of insufficient moisture in the cell. If the actual drag water flow rate is less than the target drag water flow rate, and the number of cells with voltage lower than the threshold exceeds 5% of the total number of cells, it is determined that the self-humidification condition is poor. Or the ambient temperature and humidity, as well as the gas temperature and humidity entering the stack, can be measured, and the target drag water flow rate can be adjusted according to the ambient conditions to adapt to different operating conditions. If the actual drag water flow rate is within the adjusted target drag water flow rate range and the voltage of the single cell is stable, it can be determined that the self-humidification condition is good. Or the standard deviation of the voltages of all single cells can also be calculated to evaluate the voltage consistency. Determine the consistency threshold of the voltage distribution. For example, the standard deviation is less than 0.1 volts. If the actual drag water flow rate is between 90% and 110% of the target drag water flow rate, but the voltage standard deviation exceeds the consistency threshold, it can be considered that the self-humidification condition is excessive, indicating that there may be problems such as flooding or uneven moisture distribution.

[0041] Therefore, the operating parameters of the fuel cell stack can be adjusted according to the self-humidifying state. For example, if the self-humidifying state is poor self-humidification (i.e., the amount of water in the fuel cell stack is small), it may be necessary to increase the cathode purge amount or adjust the cathode stoichiometry to increase the amount of water. If the self-humidifying state is excessive self-humidification (i.e., the amount of water in the fuel cell stack is large), it may be necessary to increase the opening duration of the anode drain valve or reduce the rotational speed of the circulation water pump to reduce the amount of water, etc. Thus, without an external humidifier, the weight and volume of the fuel cell stack system can be reduced, the difficulty of mechanical layout can be decreased, the mechanical integration efficiency can be increased, the cost is relatively low, and the self-humidification and water management are controllable, thereby increasing the operating reliability and operating efficiency.

[0042] According to an embodiment of the present application, determining the self-humidifying state of the fuel cell stack based on the actual water drag flow rate, the target water drag flow rate, and the voltage value of each single cell includes: when the actual water drag flow rate is greater than or equal to the target water drag flow rate and less than the target water drag flow rate plus a preset flow rate threshold, or when the average voltage value of all single cells is greater than a preset average voltage threshold and the standard deviation of the voltages of all single cells is less than a preset standard deviation threshold, determining that the self-humidifying state of the fuel cell stack is a first self-humidifying state, where the first self-humidifying state indicates that the actual water drag flow rate is within a preset water flow rate range; when the actual water drag flow rate is greater than or equal to the target water drag flow rate plus the preset flow rate threshold and there is a single cell with a voltage value lower than the preset voltage threshold, or when the actual water drag flow rate is greater than or equal to the target water drag flow rate plus the preset flow rate threshold and the standard deviation of the voltages of all single cells is less than the preset standard deviation threshold, determining that the self-humidifying state of the fuel cell stack is a second self-humidifying state, where the second self-humidifying state indicates that the actual water drag flow rate exceeds the preset water flow rate range; when the actual water drag flow rate is less than the target water drag flow rate and the average voltage value of all single cells is less than the preset average voltage threshold, or when the actual water drag flow rate is less than the target water drag flow rate and the standard deviation of the voltages of all single cells is greater than the preset standard deviation threshold, or when the actual water drag flow rate is less than the target water drag flow rate and there is a single cell with a voltage value lower than the preset voltage threshold, determining that the self-humidifying state of the fuel cell stack is a third self-humidifying state, where the third self-humidifying state indicates that the actual water drag flow rate is less than the preset water flow rate range. Among them, the preset flow rate threshold, the preset average voltage threshold, the preset standard deviation threshold, the preset voltage threshold, and the preset water flow rate range can be determined according to the actual situation.

[0043] Specifically, when determining the self-humidifying state of the fuel cell stack based on the actual dragged water flow rate, the target dragged water flow rate, and the voltage value of each single cell, first, the magnitude relationship between the actual dragged water flow rate and the target dragged water flow rate is judged. When the actual dragged water flow rate is greater than or equal to the target dragged water flow rate and less than the target dragged water flow rate plus a preset flow rate threshold, the self-humidifying state of the fuel cell stack can be determined to be the first self-humidifying state. That is to say, the current actual dragged water flow rate is within the preset water flow rate range, which means that the water management of the fuel cell stack system is in an ideal state, the current self-humidifying condition is good, and no additional adjustment is required. Or, the magnitude relationship between the average voltage of the single cells and the preset average voltage threshold, and the standard deviation of the voltages of all single cells and the preset standard deviation threshold can also be judged. When the average voltage of all single cells is greater than the preset average voltage threshold and the standard deviation of the voltages of all single cells is less than the preset standard deviation threshold, the self-humidifying state of the fuel cell stack can be determined to be the first self-humidifying state. That is to say, the current actual dragged water flow rate is within the preset water flow rate range, which means that the water management of the fuel cell stack system is in an ideal state, the current self-humidifying condition is good, and no additional adjustment is required.

[0044] Judge the magnitude relationship between the actual dragged water flow rate and the target dragged water flow rate, and judge the magnitude relationship between the voltage value of the single cell and the preset voltage threshold. When the actual dragged water flow rate is greater than or equal to the dragged water flow rate plus the preset flow rate threshold and there is a single cell with a voltage value lower than the preset voltage threshold, it indicates that due to the electroosmotic effect, the flow rate of water molecules dragged by hydrogen protons when passing through the membrane electrode, that is, the current actual dragged water flow rate is large, which means that too much water is dragged to the cathode. This may cause excessive moisture in the cathode area. And in the fuel cell stack, if the voltage of a certain single cell is significantly lower than that of other cells, it indicates that there may be a flooding phenomenon inside the fuel cell. Flooding will prevent the reaction gas from reaching the catalyst layer, affecting the electrochemical reaction and thus causing the voltage to decrease. Therefore, the self-humidifying state of the fuel cell stack can be determined to be the second self-humidifying state, that is, it means that the actual dragged water flow rate exceeds the preset water flow rate range, and there may be a risk of flooding, and measures need to be taken to reduce the water flow rate.

[0045] Alternatively, judge the magnitude relationship between the actual drag water flow rate and the target drag water flow rate, and judge the magnitude relationship between the voltage standard deviation of all single cells and the preset standard deviation threshold. When the actual drag water flow rate is greater than or equal to the drag water flow rate plus the preset flow threshold and the voltage standard deviation of all single cells is less than the preset standard deviation threshold, it indicates that the current actual drag water flow rate is relatively large, and the small voltage standard deviation indicates that the voltage difference of each single cell in the stack is small. However, if this situation occurs when the actual drag water flow rate is too large, it means that there is generally too much water in the entire fuel cell stack, rather than a problem with individual cells. Therefore, the self-humidification state of the fuel cell stack can be determined to be the second self-humidification state, that is, it means that the actual drag water flow rate exceeds the preset water flow range, and there may be a risk of flooding, and measures need to be taken to reduce the water flow rate.

[0046] Judge the magnitude relationship between the actual drag water flow rate and the target drag water flow rate, and judge the magnitude relationship between the average voltage of all single cells and the preset average voltage threshold. When the actual drag water flow rate is less than the target drag water flow rate and the average voltage of all single cells is less than the preset average voltage threshold, it indicates the water molecule flow rate dragged when hydrogen protons pass through the membrane electrode due to electroosmosis. If the actual drag water flow rate is too small, it means that the water replenishment inside the fuel cell stack is insufficient, which may cause the membrane electrode to be too dry, and the average voltage of a single piece being lower than the preset average voltage threshold may indicate that the performance of many single cells in the fuel cell stack is poor, which may be due to insufficient water causing proton conduction to be blocked, affecting the progress of the electrochemical reaction. Therefore, the self-humidification state of the fuel cell stack can be determined to be the third self-humidification state, indicating that the actual drag water flow rate is less than the preset water flow range, that is, the fuel cell stack system may be too dry, and water flow needs to be increased to keep the membrane electrode moist and improve battery performance.

[0047] Alternatively, judge the magnitude relationship between the actual drag water flow rate and the target drag water flow rate, and judge the magnitude relationship between the voltage standard deviation of all single cells and the preset standard deviation threshold. When the actual drag water flow rate is less than the target drag water flow rate and the voltage standard deviation of all single cells is greater than the preset standard deviation threshold, it indicates that the current actual drag water flow rate is too small, and the large voltage standard deviation indicates that the voltage difference of each single cell in the stack is significant, which may be due to uneven water distribution inside the stack or too little water in some cells, resulting in a decline in the performance of some cells. Therefore, the self-humidification state of the fuel cell stack can be determined to be the third self-humidification state, indicating that the actual drag water flow rate is less than the preset water flow range, that is, the fuel cell stack system may be too dry, and water flow needs to be increased to keep the membrane electrode moist and improve battery performance.

[0048] Alternatively, judge the magnitude relationship between the actual drag water flow rate and the target drag water flow rate, and judge the magnitude relationship between the voltage value of a single cell and the preset voltage threshold. When the actual drag water flow rate is less than the target drag water flow rate and there is a single cell with a voltage value lower than the preset voltage threshold, it indicates that the current actual drag water flow rate is too small, and the voltage of a single cell in the fuel cell stack is significantly lower than that of other cells. This usually indicates that the cell may be too dry, proton conduction is blocked, or the cell performance has decreased due to other local problems. Thus, it can be determined that the self-humidification state of the fuel cell stack is the third self-humidification state, indicating that the actual drag water flow rate is less than the preset water flow rate range, that is, the fuel cell stack system may be too dry and water flow needs to be increased to keep the membrane electrode moist and improve cell performance.

[0049] Thus, the water management state of the fuel cell stack can be monitored in real time, and corresponding control strategies can be adopted according to the self-humidification state to ensure that the fuel cell stack operates in the best state.

[0050] According to an embodiment of the present application, the operating parameters of the fuel cell stack include at least one of the cathode pressure and the anode pressure, the rotation speed of the circulation water pump, the opening duration of the anode drain valve, the cathode purge volume, and the cathode stoichiometry ratio. Adjusting the operating parameters of the fuel cell stack based on the self-humidification state includes: keeping the operating parameters unchanged when the self-humidification state is the first self-humidification state; controlling at least one of the cathode pressure being greater than the anode pressure, reducing the rotation speed, increasing the opening duration, increasing the cathode purge flow rate, and increasing the cathode stoichiometry ratio when the self-humidification state is the second self-humidification state; controlling at least one of the cathode pressure being less than the anode pressure, increasing the rotation speed, decreasing the opening duration, decreasing the cathode purge flow rate, and decreasing the cathode stoichiometry ratio when the self-humidification state is the third self-humidification state.

[0051] Specifically, the operating parameters of the fuel cell stack include at least one of the cathode pressure and the anode pressure, the rotational speed of the circulation water pump, the opening duration of the anode drain valve, the cathode purge volume, and the cathode stoichiometry ratio. That is, the cathode pressure refers to the pressure at the cathode (oxygen inlet) of the fuel cell. The cathode pressure affects the supply amount of oxygen, and thus affects the rate of the electrochemical reaction and the performance of the stack. The anode pressure refers to the pressure at the anode (hydrogen inlet) of the fuel cell. The anode pressure also affects the supply amount of hydrogen and has a direct impact on the performance and efficiency of the stack. The circulation water pump is used to circulate the coolant or cooling water to maintain the temperature stability of the stack. The rotational speed of the pump determines the flow rate and velocity of the coolant, thereby affecting the cooling efficiency and the temperature distribution of the stack. The anode drain valve is responsible for discharging the liquid water generated at the anode. Its opening duration determines the drainage frequency and amount, which is very important for controlling the moisture level inside the stack and preventing flooding. Cathode purge means purging a gas (usually air or nitrogen) through the cathode to help remove excess moisture and heat and keep the cathode dry and with good gas exchange. The amount of purge directly affects the humidity and temperature of the cathode. The cathode stoichiometry ratio is the ratio of the oxygen flow rate entering the cathode to the designed flow rate of the stack. This ratio affects the supply amount of oxygen and thus affects the efficiency of the electrochemical reaction and the performance of the stack. The adjustment of these parameters needs to be judged based on the real-time operating data of the stack and the self-humidifying state. For example, if it is detected that there is too much moisture inside the stack, it may be necessary to increase the opening duration of the anode drain valve or increase the cathode purge volume to reduce the moisture. On the contrary, if there is insufficient moisture inside the stack, it may be necessary to reduce the purge volume or adjust the cathode stoichiometry ratio to increase the moisture. These adjustments are usually automatically completed by the stack control system to keep the stack operating in the best working state.

[0052] Specifically, when adjusting the operating parameters of the fuel cell stack according to the self-humidifying state, the current self-humidifying state is judged. If the current self-humidifying state is the first self-humidifying state, it indicates that the current actual water drag flow rate is within the preset water flow rate range, indicating that the water management of the stack is in an ideal state. In this case, there is no need to adjust the operating parameters, and the current parameters are kept unchanged to maintain the best operating state of the stack.

[0053] If the current self - humidifying state is the second self - humidifying state, it indicates that the actual drag water flow exceeds the preset water flow range, and there may be a risk of waterlogging. One or more of the following operations can be controlled: the cathode pressure is greater than the anode pressure, the rotation speed is reduced, the opening duration is increased, the cathode purge flow rate is increased, and the cathode stoichiometry is increased, so as to reduce the actual drag water flow and thus reduce the risk of waterlogging. That is, by increasing the pressure on the cathode side, it helps to discharge the excess moisture from the cathode to the anode. Reducing the rotation speed of the circulation pump can reduce the flow rate of the circulating water and reduce the risk of waterlogging. Increasing the opening time of the drain valve can discharge more liquid water. Increasing the flow rate of the purge gas helps to remove the excess moisture on the cathode side, and increasing the gas flow rate of the cathode improves the removal efficiency of water vapor.

[0054] If the current self - humidifying state is the third self - humidifying state, it indicates that the actual drag water flow is less than the preset water flow range, which means the fuel cell stack may be too dry. One or more of the following operations can be controlled: the cathode pressure is less than the anode pressure, the rotation speed is increased, the opening duration is reduced, the cathode purge flow rate is reduced, and the cathode stoichiometry is reduced, so as to increase the actual drag water flow, improve the moisture condition inside the fuel cell stack, ensure the proper wetting of the membrane - electrode assembly, thereby reducing the resistance of proton conduction and improving the efficiency of the electrochemical reaction. That is, by reducing the pressure on the cathode side, it promotes the movement of moisture from the anode to the cathode. Increasing the flow rate of the circulating water can increase the moisture inside the fuel cell stack. Reducing the opening time of the drain valve can reduce the discharge of liquid water. Reducing the flow rate of the purge gas can reduce the removal of moisture, and reducing the gas flow rate of the cathode can reduce the removal of water vapor.

[0055] Thus, by dynamically adjusting the above - mentioned parameters, this closed - loop control strategy can ensure that the fuel cell stack maintains the optimal water management state under different operating conditions, can effectively control the water management of the fuel cell stack, avoid the situations of waterlogging and over - drying, ensure that the fuel cell stack can operate efficiently and stably under various working conditions, contribute to improving the reliability and economy of the fuel cell system, thereby improving the performance and lifespan of the fuel cell stack, and is of great significance for new energy vehicles and other fuel cell application fields.

[0056] According to an embodiment of the present application, the internal water flow parameters include: the liquid water flow rate and the gaseous water flow rate of water molecules moving from the cathode to the anode under the action of concentration - difference diffusion, and the pressure - difference diffusion water flow rate of water molecules moving from the cathode to the anode under the action of pressure difference. The external water flow parameters include: the drainage volume of the anode and the water circulation flow rate of the anode. Determining the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electro - osmotic force based on the internal water flow parameters and the external water flow parameters includes: subtracting the pressure - difference diffusion water flow rate and the anode drainage volume from the sum of the liquid water flow rate, the gaseous water flow rate, the anode water circulation flow rate, and a preset flow threshold. Among them, the preset flow threshold can be determined according to the actual situation.

[0057] Specifically, the internal water flow parameters may include the liquid water flow rate and the gaseous water flow rate of water molecules moving from the cathode to the anode under the action of concentration difference diffusion. That is, after water is generated at the cathode, the liquid water concentration at the cathode is greater than that at the anode. The liquid water flow rate f1 is the flow rate of water molecules passing through the membrane electrode from the cathode to the anode through concentration difference diffusion. Similarly, due to the concentration difference, the gaseous water flow rate f2 is the flow rate of gaseous water molecules diffusing from the cathode to the anode. The internal water flow parameters also include the differential diffusion water flow rate of water molecules moving from the cathode to the anode under the action of the pressure difference. That is, due to the different working pressures of the cathode and the anode, the pressure difference causes water molecules to move from the side with higher pressure to the side with lower pressure. The flow rate of this part of water is the differential diffusion water flow rate f4.

[0058] The external water flow parameters may include: the drainage volume of the anode and the water circulation flow rate of the anode. That is, after the gaseous water at the cathode of the fuel cell reaches the anode through diffusion movement, and then passes through the drainage valve, the excess liquid water is discharged to the atmosphere. The drainage volume of the anode can be denoted as f6. Since hydrogen at the anode cannot be directly discharged to the atmosphere, hydrogen is discharged from the anode outlet of the stack, and after passing through the circulation pump, ejector, and steam-water separator, most of the liquid water is separated, and a small amount of gaseous water and atomized water droplets follow the hydrogen into the anode inlet of the stack again. The water circulation flow rate of the anode can be denoted as f7.

[0059] Thus, when determining the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters, the actual drag water flow rate can be obtained by subtracting the differential diffusion water flow rate and the anode drainage volume from the sum of the liquid water flow rate, gaseous water flow rate, anode water circulation flow rate, and the preset flow rate threshold. That is, the actual drag water flow rate is denoted as f3, the preset flow rate threshold is denoted as V, f3 is the flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force, and this flow rate can be calculated by the following formula: f1 + f2 + f7 - f4 - f6 + V.

[0060] According to an embodiment of the present application, obtaining the gaseous water flow rate includes: obtaining the cathode humidity, anode humidity, cathode pressure, anode pressure, cathode saturated vapor pressure, and anode saturated vapor pressure of the fuel cell stack; based on the ratio of the product of the cathode saturated vapor pressure and the cathode humidity to the cathode pressure, subtracting the ratio of the product of the anode saturated vapor pressure and the anode humidity to the anode pressure, and then multiplying the result by the gaseous water diffusion coefficient to obtain the gaseous water flow rate; obtaining the differential pressure diffusion water flow rate includes: determining the differential pressure diffusion water flow rate based on the product of the pressure difference between the anode pressure and the cathode pressure and the water permeation resistance coefficient of the membrane electrode assembly, where, when the pressure difference is greater than zero, the water permeation resistance coefficient of the membrane electrode assembly is positive, and when the pressure difference is less than zero, the water permeation resistance coefficient of the membrane electrode assembly is negative; obtaining the anode drainage volume includes: determining the anode drainage volume based on the stack current and a first preset correspondence; the external water flow parameters further include the cathode drainage volume, obtaining the cathode drainage volume includes: using the result of subtracting the anode drainage volume from the ratio of the product of the number of single cells and the stack current to a preset constant as the obtained cathode drainage volume; obtaining the anode water circulation flow rate includes: determining the anode mixed gas return flow rate based on the rotation speed of the circulation pump and a second preset correspondence; determining the anode water circulation flow rate based on the product of the anode mixed gas return flow rate and the concentration coefficients of gaseous water and liquid water mist in the circulation flow rate; obtaining the target drag water flow rate includes: determining the target drag water flow rate based on a preset constant, the product of the stack current and the number of single cells.

[0061] Specifically, when obtaining the gaseous water flow rate, according to Fick's law of diffusion, the diffusion flow rate is proportional to the concentration difference, and the principle that the water molecule concentration is related to temperature, humidity, and pressure, the cathode humidity, anode humidity, cathode pressure, anode pressure, cathode saturated vapor pressure, and anode saturated vapor pressure of the fuel cell stack can be obtained. Thus, based on the ratio of the product of the cathode saturated vapor pressure and the cathode humidity to the cathode pressure, subtracting the ratio of the product of the anode saturated vapor pressure and the anode humidity to the anode pressure, and then multiplying the result by the gaseous water diffusion coefficient to obtain the gaseous water flow rate. Among them, the gaseous water diffusion coefficient k2 is a material property that describes the diffusion ability of gaseous water molecules in the stack. This coefficient can be determined through experiments or by looking up corresponding values in relevant literature. For example, it is determined by the formula where, f 2 is the gaseous water flow rate, k2 is the gaseous water diffusion coefficient, T c is the cathode saturated vapor pressure of the fuel cell stack, RH c is the cathode humidity of the fuel cell stack, P c is the cathode pressure of the fuel cell stack, T a is the anode saturated vapor pressure of the fuel cell stack, RH a is the anode humidity of the fuel cell stack, P ais the anode pressure of the fuel cell stack. Thus, through this method, the diffusion flow rate of gaseous water molecules inside the stack can be quantified, which is crucial for optimizing the water management strategy of the stack and maintaining the stack performance.

[0062] When obtaining the differential pressure diffusion water flow rate, the differential pressure diffusion water flow rate can be determined according to the product of the pressure difference between the anode pressure and the cathode pressure and the water permeation resistance coefficient of the membrane electrode. Among them, when the pressure difference is greater than zero, the water permeation resistance coefficient of the membrane electrode is positive, and when the force difference is less than zero, the water permeation resistance coefficient of the membrane electrode is negative. For example, it can be determined by the formula f 4 = k 4 (P a - P c ). Where f 4 is the differential pressure diffusion water flow rate, k 4 is the water permeation resistance coefficient of the membrane electrode, P a is the anode pressure of the fuel cell stack, and P c is the cathode pressure of the fuel cell stack. And by default, the direction of f4 is positive when permeating from the anode to the cathode. When the anode pressure is smaller than the cathode pressure, the flow rate is negative, and the water permeation direction changes to permeate from the cathode to the anode.

[0063] When obtaining the anode drainage volume, the anode drainage volume can be determined according to the stack current and the first preset correspondence. That is to say, the anode drainage can be measured. At each current point from small to large of the stack, during the stable operation time dT, use a graduated cylinder to collect the liquid water dV discharged from the anode drainage valve, then the anode liquid water flow rate dV / dT at each current point of the stack can be calculated, and then a two-dimensional table with the abscissa as the current I and the ordinate as the anode water flow rate f6 is established. That is, through the formula f 6 = F(I), where F(I) represents a two-dimensional look-up table function with the stack current I as the independent variable and the anode liquid water flow rate as the dependent variable, and f 6 is the anode drainage volume. When determining a stack current, the anode drainage volume f 6 can be determined according to the first preset correspondence F(I).

[0064] In addition, the external water flow parameters also include the cathode drainage volume. When obtaining the cathode drainage volume, the result obtained by subtracting the anode drainage volume from the ratio of the product of the number of single cells and the stack current to a preset constant can be used as the obtained cathode drainage volume. That is to say, when the stack operates stably and reaches the equilibrium state, the mass of water is conserved. The sum of the total amount of water generated in the stack and the total amount of water entering the stack is equal to the water discharged from the stack. The water entering the stack is only a very small amount of water pumped into the stack by the air compressor from the atmosphere, which can be ignored. Then subtract the liquid water flow rate discharged from the anode, which is the total drainage volume of the cathode. That is, it is determined by the formula . Among them, f 5is the cathode drainage volume, f 6 is the anode drainage volume, I is the stack current, N is the number of single cells, and 10721 is a preset constant.

[0065] When obtaining the anode water circulation flow rate, the anode mixed gas return flow rate can be determined according to the rotation speed of the circulation pump and the second preset correspondence relationship, and the anode water circulation flow rate can be determined according to the product of the anode mixed gas return flow rate and the concentration coefficients of gaseous water and liquid water mist in the circulation flow rate. That is to say, there is a steam-water separator in the anode circulation path that can separate gaseous water and liquid water, but the separation efficiency cannot reach 100%. The separation efficiency of the steam-water separator is related to the circulation mixed gas flow rate. The larger the circulation mixed gas flow rate, the worse the steam-water separation effect, and more gaseous water or atomized water droplets will re-enter the anode. And due to the heating effect of the circulation pump, a part of the small water droplets will also be vaporized into water vapor. Therefore, the anode water circulation flow rate is positively correlated with the rotation speed of the circulation pump. It can be determined through the formula f 7 = k 7 ·F(r), where f 7 is the anode water circulation flow rate, k7 is the concentration coefficient of gaseous water and liquid water mist in the return flow rate, r is the rotation speed of the circulation pump, and F(r) is a two-dimensional look-up table function with the rotation speed r as the independent variable and the anode mixed gas return flow rate as the dependent variable. That is, after determining the rotation speed of a circulation pump, the corresponding anode water circulation flow rate can be determined.

[0066] When obtaining the target drag water flow rate, the target drag water flow rate can be determined according to the product of the preset constant, the stack current and the number of single cells. And since the hydrogen proton H + and water H 2 O pass through the membrane electrode to the cathode in the form of hydrated protons H(H 2 O)n + , where n is between 1 and 2.5, that is, one hydrogen proton drags one to two water molecules, and the movement direction is from the anode to the cathode. It can be determined through the formula , where f 3 is the target drag water flow rate, n is a value between 1 and 2.5, I is the stack current, and N is the number of single cells.

[0067] According to an embodiment of the present application, obtaining the liquid water flow rate includes: obtaining the cathode stoichiometry of the fuel cell stack; determining the liquid water flow rate based on the stack current, the number of single cells, the cathode stoichiometry, the cathode humidity, the cathode pressure, the cathode saturation vapor pressure, the gaseous water flow rate, the target drag water flow rate, the cathode drainage volume, and the anode drainage volume.

[0068] Further, according to an embodiment of the present application, the liquid water flow rate is determined by the following formula:

[0069]

[0070] Among them, f 1 is the liquid water flow rate, k 1 is the liquid water diffusion coefficient, I is the stack current, N is the number of single cells, λ represents the cathode stoichiometry ratio, P c is the cathode pressure, RH c is the cathode humidity, T c is the cathode saturated vapor pressure, f 2 is the gaseous water flow rate, f 3 is the target drag water flow rate, f 5 is the cathode drainage volume, f 6 is the anode drainage volume.

[0071] Specifically, when obtaining the liquid water flow rate, the cathode stoichiometry ratio of the fuel cell stack can be obtained. The cathode stoichiometry ratio refers to the ratio of the gas flow rate entering the cathode to the designed flow rate of the stack. And according to Fick's diffusion law, the diffusion flow rate is proportional to the concentration difference. The amount of liquid water at the cathode is the total amount of water generated minus the amount of vaporized water, minus the amount of water purged and discharged. The amount of liquid water at the anode is the water flow rate permeating from the cathode to the anode at the previous moment minus the liquid water flow rate purged at the anode, minus the water flow rate of electroosmotic drag. The anode humidity is the recycled gas, and the amount of vaporized liquid water at the anode can be ignored. Then the liquid water flow rate can be determined based on the stack current, the number of single cells, the cathode stoichiometry ratio, the cathode humidity, the cathode pressure, the cathode saturated vapor pressure, the gaseous water flow rate, the target drag water flow rate, the cathode drainage volume, and the anode drainage volume. That is, through the above formula, according to the liquid water diffusion coefficient k 1 , the stack current I, the number of single cells N, the cathode stoichiometry ratio λ, the cathode pressure P c , the cathode humidity RH c , the cathode saturated vapor pressure T c , the gaseous water flow rate f 2 , the target drag water flow rate f 3 , the cathode drainage volume f 5 , the anode drainage volume f 6 to determine the liquid water flow rate f 1 .

[0072] In summary, after determining the liquid water flow rate f 1 , the gaseous water flow rate f 2 , the target drag water flow rate f 3 , the differential pressure diffusion water flow rate f 4 , the cathode drainage volume f 5 , the anode drainage volume f 6 , the anode water circulation flow rate f 7 , f1 to f7 can be substituted into the above After that, it can be simplified to: Thus, in combination with this formula, the self-humidifying state of the fuel cell stack can be determined, and then the operating parameters of the fuel cell stack can be adjusted according to the self-humidifying state. Therefore, an external humidifier is not required, which can reduce the weight and volume of the engine, increase the mass density and volume density of the engine, reduce the difficulty of the mechanical layout of the system, increase the mechanical integration efficiency, and the cost is relatively low. Moreover, by adopting control strategies such as precise process analysis of water management inside the stack, self-humidifying control algorithms, and humidifying state judgment, the self-humidifying and water management are controllable processes, which increases the operating reliability and operating efficiency of the fuel cell stack system.

[0074] Next, in combination with Figure 2 the following describes the method of the present application.

[0075] As a specific example, the water management control method of the fuel cell stack system of the present application may include the following steps:

[0076] S101, obtain the liquid water flow rate and gaseous water flow rate of water molecules moving from the cathode to the anode under the action of concentration difference diffusion, the pressure difference diffusion water flow rate of water molecules moving from the cathode to the anode under the action of pressure difference, and obtain the drainage volume of the anode and the water circulation flow rate of the anode.

[0077] S102, based on the sum of the liquid water flow rate, gaseous water flow rate, anode water circulation flow rate, and a preset flow rate threshold, subtract the pressure difference diffusion water flow rate and the anode drainage volume to obtain the actual drag water flow rate.

[0078] S103, determine whether the actual drag water flow rate is greater than or equal to the target drag water flow rate and less than the target drag water flow rate plus the preset flow rate threshold, or whether the average voltage value of all single cells is greater than the preset average voltage threshold and the voltage standard deviation of all single cells is less than the preset standard deviation threshold. If so, execute step S104; if not, execute step S105.

[0079] S104, determine that the self-humidifying state of the fuel cell stack is the first self-humidifying state, where the first self-humidifying state indicates that the actual drag water flow rate is within the preset water flow rate range, and enter step S109.

[0080] S105, determine whether the actual drag water flow rate is greater than or equal to the drag water flow rate plus the preset flow rate threshold and whether there is a single cell with a voltage value lower than the preset voltage threshold, or whether the actual drag water flow rate is greater than or equal to the drag water flow rate plus the preset flow rate threshold and the voltage standard deviation of all single cells is less than the preset standard deviation threshold. If so, execute step S106; if not, execute step S107.

[0081] S106, determine that the self - humidifying state of the fuel cell stack is the second self - humidifying state, where the second self - humidifying state indicates that the actual water drag flow rate exceeds the preset water flow rate range, and proceed to step S110.

[0082] S107, determine whether the actual water drag flow rate is less than the target water drag flow rate and whether the average voltage of all single cells is less than the preset average voltage threshold, or whether the actual water drag flow rate is less than the target water drag flow rate and whether the standard deviation of the voltages of all single cells is greater than the preset standard deviation threshold, or whether the actual water drag flow rate is less than the target water drag flow rate and whether there is a single cell with a voltage value lower than the preset voltage threshold. If so, execute step S108; if not, execute step S101.

[0083] S108, determine that the self - humidifying state of the fuel cell stack is the third self - humidifying state, where the third self - humidifying state indicates that the actual water drag flow rate is less than the preset water flow rate range, and proceed to step S111.

[0084] S109, keep the operating parameters of the fuel cell stack unchanged, and proceed to step S101.

[0085] S110, control at least one of the cathode pressure being greater than the anode pressure, reducing the rotational speed of the circulation water pump, increasing the opening duration of the anode drain valve, increasing the cathode purge flow rate, and increasing the cathode stoichiometry ratio, and proceed to step S101.

[0086] S111, control at least one of the cathode pressure being less than the anode pressure, increasing the rotational speed of the circulation water pump, reducing the opening duration of the anode drain valve, reducing the cathode purge flow rate, and reducing the cathode stoichiometry ratio, and proceed to step S101.

[0087] In summary, according to the water management control method of the fuel cell stack system in the embodiments of the present application, the internal water flow parameters of the water molecule movement inside the fuel cell stack and the external water flow parameters of the water molecule movement outside are obtained. Based on the internal water flow parameters and the external water flow parameters, the actual water drag flow rate of the water molecules flowing from the anode to the cathode under the action of the electro - osmotic force is determined. Based on the actual water drag flow rate, the target water drag flow rate, and the voltage value of each single cell, the self - humidifying state of the fuel cell stack is determined. Based on the self - humidifying state, the operating parameters of the fuel cell stack are adjusted. Thus, this method does not require an external humidifier, can reduce the weight and volume of the fuel cell stack system, and reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, has a lower cost, and the self - humidification and water management are controllable, thereby increasing the operation reliability and operation efficiency.

[0088] Corresponding to the above - mentioned embodiments, the present application also proposes a water management control device for a fuel cell stack system.

[0089] As Figure 3As shown in the figure, the water management control device 100 of the fuel cell stack system according to the embodiment of the present application includes: an acquisition module 110, a first determination module 120, a second determination module 130, and an adjustment module 140.

[0090] Among them, the acquisition module 110 is used to acquire the internal water flow parameters of the movement of water molecules inside the fuel cell stack and the external water flow parameters of the movement of water molecules outside. The first determination module 120 is used to determine the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters. The second determination module 130 is used to determine the self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell. The adjustment module 140 is used to adjust the operating parameters of the fuel cell stack based on the self-humidification state.

[0091] According to an embodiment of the present application, the second determination module 130 determines the self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell. Specifically, it is used to: when the actual drag water flow rate is greater than or equal to the target drag water flow rate and less than the target drag water flow rate plus the preset flow threshold, or when the average voltage value of all single cells is greater than the preset average voltage threshold and the standard deviation of the voltage of all single cells is less than the preset standard deviation threshold, determine that the self-humidification state of the fuel cell stack is the first self-humidification state, where the first self-humidification state means that the actual drag water flow rate is within the preset water flow range; when the actual drag water flow rate is greater than or equal to the drag water flow rate plus the preset flow threshold and there is a single cell with a voltage value lower than the preset voltage threshold, or when the actual drag water flow rate is greater than or equal to the drag water flow rate plus the preset flow threshold and the standard deviation of the voltage of all single cells is less than the preset standard deviation threshold, determine that the self-humidification state of the fuel cell stack is the second self-humidification state, where the second self-humidification state means that the actual drag water flow rate exceeds the preset water flow range; when the actual drag water flow rate is less than the target drag water flow rate and the average voltage value of all single cells is less than the preset average voltage threshold, or when the actual drag water flow rate is less than the target drag water flow rate and the standard deviation of the voltage of all single cells is greater than the preset standard deviation threshold, or when the actual drag water flow rate is less than the target drag water flow rate and there is a single cell with a voltage value lower than the preset voltage threshold, determine that the self-humidification state of the fuel cell stack is the third self-humidification state, where the third self-humidification state means that the actual drag water flow rate is less than the preset water flow range.

[0092] According to an embodiment of the present application, the operating parameters of the fuel cell stack include at least one of the cathode pressure and the anode pressure, the rotational speed of the circulation water pump, the opening duration of the anode drain valve, the cathode purge amount, and the cathode stoichiometry ratio. The adjustment module 140 adjusts the operating parameters of the fuel cell stack based on the self-humidifying state, and is specifically configured to: keep the operating parameters unchanged when the self-humidifying state is the first self-humidifying state; control at least one of the cathode pressure being greater than the anode pressure, reducing the rotational speed, increasing the opening duration, increasing the cathode purge flow rate, and increasing the cathode stoichiometry ratio when the self-humidifying state is the second self-humidifying state; control at least one of the cathode pressure being less than the anode pressure, increasing the rotational speed, decreasing the opening duration, decreasing the cathode purge flow rate, and decreasing the cathode stoichiometry ratio when the self-humidifying state is the third self-humidifying state.

[0093] According to an embodiment of the present application, the internal water flow parameters include: the liquid water flow rate and the gaseous water flow rate of water molecules moving from the cathode to the anode under the action of concentration difference diffusion, and the pressure difference diffusion water flow rate of water molecules moving from the cathode to the anode under the action of pressure difference. The external water flow parameters include: the drainage volume of the anode and the anode water circulation flow rate. The acquisition module 110 determines the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters, and is specifically configured to: subtract the pressure difference diffusion water flow rate and the anode drainage volume from the sum of the liquid water flow rate, the gaseous water flow rate, the anode water circulation flow rate, and a preset flow rate threshold to obtain the actual drag water flow rate.

[0094] According to an embodiment of the present application, the acquisition module 110 acquires the gaseous water flow rate, specifically for: acquiring the cathode humidity, anode humidity, cathode pressure, anode pressure, cathode saturated vapor pressure, and anode saturated vapor pressure of the fuel cell stack; based on the ratio of the product of the cathode saturated vapor pressure and the cathode humidity to the cathode pressure, subtracting the result of the ratio of the product of the anode saturated vapor pressure and the anode humidity to the anode pressure, and then multiplying by the gaseous water diffusion coefficient to obtain the gaseous water flow rate; acquiring the pressure difference diffusion water flow rate, including: determining the pressure difference diffusion water flow rate based on the product of the pressure difference between the anode pressure and the cathode pressure and the water permeation resistance coefficient of the membrane electrode, wherein, when the pressure difference is greater than zero, the water permeation resistance coefficient of the membrane electrode is positive, and when the pressure difference is less than zero, the water permeation resistance coefficient of the membrane electrode is negative; acquiring the anode drainage volume, including: determining the anode drainage volume based on the stack current and the first preset correspondence; the external water flow parameters further include the cathode drainage volume, acquiring the cathode drainage volume, including: using the result of subtracting the anode drainage volume from the ratio of the product of the number of single cells and the stack current to a preset constant as the acquired cathode drainage volume; acquiring the anode water circulation flow rate, including: determining the anode mixed gas return flow rate based on the rotation speed of the circulation pump and the second preset correspondence; determining the anode water circulation flow rate based on the product of the anode mixed gas return flow rate and the concentration coefficient of gaseous water and liquid water mist in the circulation flow rate; acquiring the target drag water flow rate, including: determining the target drag water flow rate based on a preset constant, the product of the stack current and the number of single cells.

[0095] According to an embodiment of the present application, the acquisition module 110 acquires the liquid water flow rate, specifically for: acquiring the cathode stoichiometry of the fuel cell stack; determining the liquid water flow rate based on the stack current, the number of single cells, the cathode stoichiometry, the cathode humidity, the cathode pressure, the cathode saturated vapor pressure, the gaseous water flow rate, the target drag water flow rate, the cathode drainage volume, and the anode drainage volume.

[0096] According to an embodiment of the present application, the acquisition module 110 determines the liquid water flow rate through the following formula:

[0097]

[0098] where f 1 is the liquid water flow rate, k 1 is the liquid water diffusion coefficient, I is the stack current, N is the number of single cells, λ represents the cathode stoichiometry, P c is the cathode pressure, RH c is the cathode humidity, T c is the cathode saturated vapor pressure, f 2 is the gaseous water flow rate, f 3 is the target drag water flow rate, f 5 is the cathode drainage volume, f 6 is the anode drainage volume.

[0099] It should be noted that for the details not disclosed in the water management control device of the fuel cell stack system according to the embodiments of the present application, please refer to the details disclosed in the water management control method of the fuel cell stack system according to the embodiments of the present application, and specific details will not be elaborated here.

[0100] According to the water management control device of the fuel cell stack system according to the embodiments of the present application, an acquisition module is used to acquire internal water flow parameters of the movement of water molecules inside the fuel cell stack and external water flow parameters of the movement of external water molecules. A first determination module is used to determine the actual water drag flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameters and the external water flow parameters. A second determination module is used to determine the self-humidification state of the fuel cell stack based on the actual water drag flow rate, the target water drag flow rate, and the voltage value of each single cell. An adjustment module is used to adjust the operating parameters of the fuel cell stack based on the self-humidification state. Thus, the device does not require an external humidifier, can reduce the weight and volume of the fuel cell stack system, and reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, and has a lower cost. Moreover, self-humidification and water management are controllable, thereby increasing the operating reliability and operating efficiency.

[0101] Corresponding to the above embodiments, the present application also proposes a computer-readable storage medium.

[0102] The computer-readable storage medium according to the embodiments of the present application stores a program thereon, and when the program is executed by a processor, it implements the above-mentioned water management control method of the fuel cell stack system.

[0103] According to the computer-readable storage medium of the embodiments of the present application, by executing the above-mentioned water management control method of the fuel cell stack system, it does not require an external humidifier, can reduce the weight and volume of the fuel cell stack system, and reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, and has a lower cost. Moreover, self-humidification and water management are controllable, thereby increasing the operating reliability and operating efficiency.

[0104] Corresponding to the above embodiments, the present application also proposes a vehicle.

[0105] As Figure 4 shown, the vehicle 200 according to the embodiments of the present application may include: a memory 210, a processor 220, and a program stored on the memory 210 and executable on the processor 220. When the processor 220 executes the program, it implements the above-mentioned water management control method of the fuel cell stack system.

[0106] According to the vehicle of the embodiment of the present application, by implementing the above water management control method of the fuel cell stack system, without an external humidifier, it is possible to reduce the weight and volume of the fuel cell stack system, reduce the difficulty of mechanical layout, increase the mechanical integration efficiency, have a lower cost, and the self-humidification and water management are controllable, thereby increasing the operation reliability and operation efficiency.

[0107] It should be noted that the logic and / or steps represented in the flowchart or described in other ways herein, for example, can be considered as a definite sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0108] It should be understood that the various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0109] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0110] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0111] In this application, unless otherwise clearly specified and limited, the terms such as "install", "connect", "connection", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0112] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as a limitation to this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A water management control method for a fuel cell stack system, characterized in that: The fuel cell stack includes a plurality of single cells, each of which includes an anode and a cathode. The method includes: Acquiring internal water flow parameters of water molecule movement inside the fuel cell stack and external water flow parameters of water molecule movement outside the fuel cell stack; Determine the actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of electroosmotic force based on the internal water flow parameter and the external water flow parameter; determining a self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell; An operating parameter of the fuel cell stack is adjusted based on the self-humidification state.

2. The water management control method of the fuel cell stack system according to claim 1, characterized in that: Determining the self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate and the voltage value of each single cell includes: When the actual drag water flow rate is greater than or equal to the target drag water flow rate and less than the target drag water flow rate plus a preset flow rate threshold, or when the voltage average value of all single cells is greater than a preset average voltage threshold and the voltage standard deviation of all single cells is less than a preset standard deviation threshold, determining that the self-humidification state of the fuel cell stack is a first self-humidification state, wherein the first self-humidification state indicates that the actual drag water flow rate is within a preset water flow rate range; In the case where the actual drag water flow is greater than or equal to the drag water flow plus the preset flow threshold and there is a single cell with a voltage value lower than the preset voltage threshold, or in the case where the actual drag water flow is greater than or equal to the drag water flow plus the preset flow threshold and the voltage standard deviation of all single cells is less than the preset standard deviation threshold, determining that the self-humidification state of the fuel cell stack is a second self-humidification state, wherein the second self-humidification state indicates that the actual drag water flow exceeds a preset water flow range; In the case where the actual drag water flow rate is less than the target drag water flow rate and the voltage average value of all single cells is less than the preset average voltage threshold, or, in the case where the actual drag water flow rate is less than the target drag water flow rate and the voltage standard deviation of all single cells is greater than the preset standard deviation threshold, or, in the case where the actual drag water flow rate is less than the target drag water flow rate and there are single cells with voltage values ​​lower than the preset voltage threshold, it is determined that the self-humidification state of the fuel cell stack is the third self-humidification state, wherein the third self-humidification state indicates that the actual drag water flow rate is less than the preset water flow range.

3. The water management control method of the fuel cell stack system according to claim 2, characterized in that: The operating parameters of the fuel cell stack include at least one of cathode pressure and anode pressure, a rotation speed of a circulating water pump, an opening time of an anode drain valve, a cathode purge amount, and a cathode stoichiometric ratio. The adjusting of the operating parameters of the fuel cell stack based on the self-humidification state includes: When the self-humidification state is the first self-humidification state, keeping the operating parameters unchanged; When the self-humidification state is the second self-humidification state, at least one of controlling the cathode pressure to be greater than the anode pressure, reducing the rotation speed, increasing the opening time, increasing the cathode purge flow rate, and increasing the cathode stoichiometric ratio; When the self-humidification state is the third self-humidification state, at least one of controlling the cathode pressure to be less than the anode pressure, increasing the rotation speed, reducing the opening time, reducing the cathode purge flow, and reducing the cathode metering ratio is selected.

4. The water management control method of a fuel cell stack system according to claim 1, characterized in that: The internal water flow parameters include: liquid water flow and gaseous water flow of water molecules moving from the cathode to the anode under the action of concentration difference diffusion, and pressure difference diffusion water flow of water molecules moving from the cathode to the anode under the action of pressure difference. The external water flow parameters include: the water discharge of the anode and the water circulation flow of the anode. Based on the internal water flow parameters and the external water flow parameters, the actual drag water flow of water molecules flowing from the anode to the cathode under the action of electroosmotic force is determined, including: Based on the sum of the liquid water flow, the gaseous water flow, the anode water circulation flow and a preset flow threshold, the actual drag water flow is obtained by subtracting the pressure difference diffusion water flow and the anode water discharge.

5. The water management control method of the fuel cell stack system according to claim 4, characterized in that: Obtaining the gaseous water flow rate includes: Obtaining cathode humidity, anode humidity, cathode pressure, anode pressure, cathode saturated steam pressure, and anode saturated steam pressure of the fuel cell stack; Based on the ratio of the product of the cathode saturated vapor pressure and the cathode humidity to the cathode pressure, the ratio of the product of the anode saturated vapor pressure and the anode humidity to the anode pressure is subtracted, and then multiplied by the gaseous water diffusion coefficient to obtain the gaseous water flow rate; Obtaining the pressure difference diffusion water flow rate includes: The pressure difference diffusion water flow rate is determined based on the product of the pressure difference between the anode pressure and the cathode pressure and the water permeation resistance coefficient of the membrane electrode, wherein when the pressure difference is greater than zero, the water permeation resistance coefficient of the membrane electrode is a positive value, and when the pressure difference is less than zero, the water permeation resistance coefficient of the membrane electrode is a negative value; Obtaining the anode water discharge volume includes: Determining the anode water discharge amount based on the stack current and a first preset corresponding relationship; The external water flow parameter also includes cathode water discharge, and obtaining the cathode water discharge includes: Based on the ratio of the product of the number of single cells and the stack current to a preset constant, the result of subtracting the anode drainage volume is used as the cathode drainage volume; Obtaining the anode water circulation flow rate includes: Determine the anode mixed gas reflux amount based on the rotation speed of the circulation pump and the second preset corresponding relationship; Determining the anode water circulation flow rate based on the product of the anode mixed gas reflux flow rate and the concentration coefficient of the gaseous water and liquid water mist in the circulation flow rate; Get the target drag water flow, including: The target drag water flow rate is determined based on a preset constant, the product of the battery stack current and the number of the single cells.

6. The water management control method of the fuel cell stack system according to claim 5, characterized in that: Obtaining the liquid water flow rate, comprising: obtaining a cathode stoichiometric ratio of the fuel cell stack; The liquid water flow rate is determined based on the stack current, the number of single cells, the cathode stoichiometric ratio, the cathode humidity, the cathode pressure, the cathode saturated vapor pressure, the gaseous water flow rate, the target drag water flow rate, the cathode water discharge and the anode water discharge.

7. The water management control method of the fuel cell stack system according to claim 6, characterized in that: The liquid water flow rate f1 is determined by the following formula: Wherein, f1 is the liquid water flow rate, k1 is the liquid water diffusion coefficient, I is the battery stack current, N is the number of single cells, λ represents the cathode stoichiometric ratio, P c is the cathode pressure, RH c is the cathode humidity, T c is the cathode saturated steam pressure, f2 is the gaseous water flow rate, f3 is the target drag water flow rate, f5 is the cathode water discharge, and f6 is the anode water discharge.

8. A water management control device for a fuel cell stack system, characterized in that: The fuel cell stack includes a plurality of single cells, each of which includes an anode and a cathode. The device includes: An acquisition module, used to acquire internal water flow parameters of water molecule movement inside the fuel cell stack and external water flow parameters of water molecule movement outside the fuel cell stack; A first determination module, for determining an actual drag water flow rate of water molecules flowing from the anode to the cathode under the action of the electroosmotic force based on the internal water flow parameter and the external water flow parameter; a second determination module, configured to determine a self-humidification state of the fuel cell stack based on the actual drag water flow rate, the target drag water flow rate, and the voltage value of each single cell; An adjustment module is used to adjust the operating parameters of the fuel cell stack based on the self-humidification state.

9. A computer-readable storage medium, characterized in that: A program is stored thereon, and when the program is executed by a processor, the water management control method for a fuel cell stack system according to any one of claims 1 to 7 is implemented.

10. A vehicle, characterized in that: include: A memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the water management control method for a fuel cell stack system according to any one of claims 1 to 7 is implemented.

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