Vehicle-mounted fuel cell air intake humidity adjusting method and adjusting system

Abstract

The application provides a vehicle-mounted fuel cell air inlet humidity adjusting method and adjusting system. The method comprises the following steps: obtaining the stack impedance, stack working temperature and working condition information of a fuel cell; when the working condition information indicates that the working condition of the fuel cell changes, determining the membrane water content of the fuel cell according to the stack impedance and the stack working temperature; determining the air inlet humidity value under the current working condition according to the corresponding relationship between the membrane water content and the cathode relative humidity; determining the humidification change value according to the corresponding relationship between the power change value and the humidification change value; and adjusting the inlet humidity according to the air inlet humidity value under the current working condition and the humidification change value. The method can actively, quickly and accurately adjust the fuel cell inlet air humidity, and can maintain the water content in the fuel cell within a reasonable range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cells, in particular to a method and system for adjusting air humidity of a vehicle-mounted fuel cell. BACKGROUND

[0002] Proton exchange membrane fuel cell is a kind of high-efficient and clean energy conversion device which can make hydrogen and air generate water and electric energy under certain conditions. It is a promising power source for vehicles and a research hotspot of universities and research institutions at home and abroad.

[0003] Water plays a crucial role in the existing proton exchange membrane fuel cell. The conduction of protons in the proton exchange membrane must involve water, and the membrane must contain sufficient water to ensure proton conductivity. If the moisture of the membrane is too low, the performance of the fuel cell will decrease, and in extreme conditions, it may even cause permanent damage to the physical properties of the material. If the moisture of the membrane is too much and cannot be effectively discharged, it will flood the electrode, causing the performance of the fuel cell to decrease or even appear the reverse polarity phenomenon. In addition, the continuous improvement of the working current density of the fuel cell exacerbates the uneven distribution of internal water state, and the local water content is too low and the local water saturation is too high. How to maintain the water balance of the fuel cell is one of the research hotspots of proton exchange membrane fuel cells. Maintaining the water balance of the fuel cell not only has an important influence on improving the performance of the fuel cell, but also is crucial to prolonging the service life of the fuel cell.

[0004] The vehicle-mounted fuel cell system involves start-stop, overload and idle running and other operating conditions during operation. Different operating conditions have different requirements for air humidity, and rapid adjustment of air humidity is required when the operating conditions change. At the same time, when the humidity of the fuel cell working environment changes, the performance of the humidifier also needs to be adjusted accordingly to keep the air humidity within a reasonable range.

[0005] In the prior art, the following methods are used to adjust the moisture of the membrane of the fuel cell: 1. The moisture is adjusted by switching the air path, so that the gas flows through different moisture content humidifying devices to achieve humidification or dehumidification effect. However, this method requires two sets of humidifying devices, which increases the size and cost of the fuel cell system, and is not suitable for vehicle-mounted environment. 2. The moisture is adjusted by combining a humidity regulator with a humidifying device. The humidity regulator adjusts the air humidity into the stack by controlling the air flow on the wet side of the humidifier according to the instructions of the fuel cell control unit. However, this method has a slow response speed, and when dry gas is needed, it cannot provide dry gas immediately.

[0006] Therefore, there is a need for a fuel cell air inlet humidity adjusting method and adjusting device suitable for a vehicle environment, which can quickly and accurately adjust the humidity (or dryness) of the air entering the fuel cell stack, so as to maintain the water content in the fuel cell within a required range. SUMMARY

[0007] Therefore, the present application provides a vehicle fuel cell air inlet humidity adjusting method and adjusting system, which can actively, quickly and accurately adjust the humidity of the air entering the fuel cell stack, so as to maintain the water content in the fuel cell within a required range.

[0008] In a first aspect, the present application provides a vehicle fuel cell air inlet humidity adjusting method, comprising: obtaining the stack impedance, the stack operating temperature and the working condition information of the fuel cell; when the working condition information indicates that the working condition of the fuel cell changes, determining the membrane water content of the fuel cell according to the stack impedance and the stack operating temperature, wherein the working condition information comprises a power change value, and when the working condition changes, the power change value exceeds the preset percentage of the corresponding preset value; determining the air inlet humidity value under the current working condition according to the corresponding relationship between the membrane water content and the cathode relative humidity; determining the humidification change value according to the corresponding relationship between the power change value and the humidification change value; and adjusting the inlet humidity according to the air inlet humidity value under the current working condition and the humidification change value.

[0009] The vehicle fuel cell system involves start-stop, overload and idle and other operating conditions in the working process, and different operating conditions have different requirements for the inlet humidity. By determining the operating condition according to the working condition information, the air inlet humidity under different operating conditions can be determined, which is suitable for vehicle scenarios. When the operating condition changes, the membrane water content of the fuel cell is determined according to the stack impedance and the stack operating temperature, so that the membrane water content of the fuel cell is determined in an active manner, and the inlet humidity is adjusted according to the above method, so that the inlet humidity reaches the required humidity under the operating condition.

[0010] In a possible implementation, the determination of the membrane water content of the fuel cell according to the stack impedance and the stack operating temperature specifically comprises: determining the membrane water content according to the following formula:

[0011]

[0012]

[0013]

[0014] wherein, R ohm is the ohmic impedance, t m is the proton exchange membrane thickness, and σ mis the membrane conductivity, b1 and b2 are empirical parameters, T st is the stack operating temperature, l m is the membrane water content, a is the water activity.

[0015] Through the above settings, the membrane water content under the current working condition can be accurately and quickly determined through the ohmic impedance, the proton exchange membrane thickness, the membrane conductivity, and the stack operating temperature, and the air inlet humidity can be quickly and accurately adjusted.

[0016] In a possible implementation, adjusting the air inlet humidity according to the air inlet humidity value under the current working condition and the humidification change value specifically includes: comparing the sum of the air inlet humidity value and the humidification change value with the humidity adjustment range of the humidifier; when the sum is within the adjustment range, adjusting the opening degree of the bypass valve of the humidifier so that the air inlet humidity is the sum; when the sum is greater than the adjustment range, closing the bypass valve of the humidifier; and when the sum is less than the adjustment range, adjusting the opening degree of the bypass valve of the humidifier to the maximum.

[0017] When the sum is greater than the adjustment range, it indicates that the humidity of the air needs to be increased as much as possible, and therefore the bypass valve of the humidifier is closed so that the air flows into the humidifier for humidification. When the sum is less than the adjustment range, it indicates that the humidity of the air needs to be reduced, and therefore the opening degree of the bypass valve of the humidifier is adjusted to the maximum so that the air does not flow into the humidifier as much as possible. When the sum is within the adjustment range, it indicates that it is most appropriate to maintain the air inlet humidity at the sum, and therefore the opening degree of the bypass valve is adjusted larger or smaller by PID until the temperature and humidity pressure sensor detects that the air inlet humidity value is the sum. The air inlet humidity (or dryness) is adjusted by adjusting the opening degree of the bypass valve, which is simple and rapid in adjustment and suitable for vehicle-mounted scenes.

[0018] In a possible implementation, after adjusting the air inlet humidity according to the air inlet humidity value under the current working condition and the humidification change value, the method further includes: obtaining the working condition information of the stack; and when the power change value is greater than a preset percentage of the rated power, repeating the above steps.

[0019] Through the above settings, the air inlet humidity can be adjusted in real time according to the change of the power, the air inlet humidity of the stack is corrected in real time in a closed loop, the membrane is kept within the target humidity range, the control of the membrane humidity is more accurate, and therefore the proton exchange membrane of the fuel cell stack is ensured to operate at an appropriate working humidity.

[0020] In a possible implementation, the preset percentage is 0.4% to 0.8%.

[0021] In a possible implementation, the method further includes: obtaining the stack operating temperature; when the stack operating temperature is greater than 0℃, performing the above steps; and when the stack operating temperature is less than 0℃, adjusting the opening degree of the bypass valve of the humidifier to the maximum.

[0022] Through the above arrangement, it can be determined whether the stack temperature is greater than 0℃ after the fuel cell starts operating, when the stack temperature is less than 0℃, the dry air is used to perform low-temperature purging on the stack, and when the stack temperature rises to 0℃, the normal start-up operation is performed, thereby shortening the time of cold start of the stack.

[0023] In a second aspect, the application provides a vehicle-mounted fuel cell air inlet humidity adjusting system, comprising: an air filter, an air compressor, a intercooler, a humidifier, a bypass valve, a fuel cell, a controller and an impedance detection device, the fuel cell has a stack, wherein the outlet of the air filter is connected with the inlet of the air compressor; the outlet of the air compressor is connected with the inlet of the intercooler; the outlet of the intercooler is connected with the first inlet of the humidifier; the first outlet of the humidifier is connected with the cathode inlet of the stack; one end of the bypass valve is connected with the outlet of the intercooler; the other end of the bypass valve is connected with the first outlet of the humidifier; the cathode outlet of the stack is connected with the second inlet of the humidifier; the second outlet of the humidifier is connected with the outside; the impedance detection device is connected with the fuel cell; the controller is connected with the bypass valve and the impedance detection device, and is used for controlling the opening degree of the bypass valve according to the adjusting method of the first aspect.

[0024] Through the above structure, the humidity (or dryness) of the membrane can be adjusted without multiple humidifying devices, the structure is simple, and the vehicle-mounted fuel cell system is suitable; through the impedance detection device, the impedance of the stack can be quickly and actively obtained, the required air inlet humidity value can be determined by the controller through the adjusting method, the opening degree of the bypass valve is controlled to adjust the air inlet humidity, the humidity of the membrane is controlled, and the air inlet humidity is actively, quickly and accurately adjusted. Under the change of the power demand of the fuel cell and the humidity of the working environment, the water content demand of the proton exchange membrane also changes, the water content of the proton exchange membrane of the fuel cell is quickly adjusted through the quick adjustment of the air inlet humidity, the water content of the membrane is maintained in a suitable range, and the performance of the stack is improved. Meanwhile, the application realizes the real-time closed-loop correction of the air inlet humidity, and the control is more accurate.

[0025] In a possible implementation, the controller comprises: a PID and a fuel cell controller.

[0026] In a possible implementation, the air humidity adjusting system further comprises a plurality of temperature and humidity pressure sensors and a back pressure valve, the plurality of temperature and humidity pressure sensors are respectively arranged between the air compressor and the intercooler, between the first outlet of the humidifier and the cathode inlet of the fuel cell stack, and between the cathode outlet of the fuel cell stack and the second inlet of the humidifier; and the back pressure valve is connected to the second outlet of the humidifier.

[0027] In a possible implementation, the air humidity adjusting system further comprises an air flow device or an air pressure sensor, one end of the air flow device or the air pressure sensor is connected to the outlet of the air filter, and the other end of the air flow device or the air pressure sensor is connected to the inlet of the air compressor. BRIEF DESCRIPTION OF DRAWINGS

[0028] Various technical features of the present application and the relationship between them will be further illustrated below with reference to the accompanying drawings. The accompanying drawings are exemplary, some technical features are not shown in actual proportion, and some technical features in the drawings can be omitted, which are conventional in the technical field to which the present application belongs and are not essential for understanding and implementing the present application, or additional technical features are shown, which are not essential for understanding and implementing the present application. That is, the combination of various technical features shown in the drawings is not used to limit the present application. In addition, the same reference signs refer to the same contents throughout the present application. Specific drawings are as follows:

[0029] Figure 1 is a structural schematic diagram of an air humidity adjusting system for a vehicle-mounted fuel cell provided by an embodiment of the present application;

[0030] Figure 2 is a schematic diagram of the air flow direction when the bypass valve of the air humidity adjusting system for a vehicle-mounted fuel cell provided by an embodiment of the present application is closed;

[0031] Figure 3 is a schematic diagram of the air flow direction when the opening degree of the bypass valve of the air humidity adjusting system for a vehicle-mounted fuel cell provided by an embodiment of the present application is adjusted to the maximum;

[0032] Figure 4 is a schematic diagram of the air flow direction when the bypass valve of the air humidity adjusting system for a vehicle-mounted fuel cell provided by an embodiment of the present application is partially opened;

[0033] Figure 5 is a flowchart of an air humidity adjusting method for a vehicle-mounted fuel cell provided by an embodiment of the present application;

[0034] Figure 6 is a schematic diagram of the corresponding relationship between the membrane water content and the cathode relative humidity of the vehicle-mounted fuel cell under partial working conditions provided by an embodiment of the present application. Detailed Implementation

[0035] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0036] Figure 1 The structure of the on-board fuel cell air intake humidity control system provided in this application embodiment is shown, such as... Figure 1 As shown, the on-board fuel cell air intake humidity control system 100 (hereinafter referred to as the system) provided in this application embodiment includes the following components connected to each other via pipelines: an air filter 1 for filtering out dust, sand, etc. from the air; an air compressor 3 for compressing air; an intercooler 5 for cooling the compressed air; a humidifier 6 for humidifying the cooled air; a bypass valve 7 for controlling the amount of gas flowing through the humidifier 6 and the dry side; a fuel cell with a stack 10; an impedance detection device 9 for detecting the impedance of the fuel cell stack 10; and a controller 13 for controlling the opening of the bypass valve 7 via wired or wireless means. In some embodiments, the system 100 may further include a back pressure valve 12 for maintaining the required pressure inside the system's pipelines; an air flow device 2 for detecting air flow rate; temperature, humidity, and pressure sensors 4, 8, and 11 for detecting the temperature, humidity, and pressure within the corresponding pipelines of the system; and a stack temperature sensor 16 for detecting the stack temperature.

[0037] like Figure 1 As shown, the outlet of the air filter 1 is connected to one end of the air flow device 2, and the other end of the air flow device 2 is connected to the inlet of the air compressor 3; the outlet of the air compressor 3 is connected to the inlet of the intercooler 5; the outlet of the intercooler 5 is connected to the first inlet 61 of the humidifier 6; the first outlet 62 of the humidifier 6 is connected to the cathode inlet 14 of the fuel cell stack 10; one end of the bypass valve 7 is connected to the outlet of the intercooler 5; the other end of the bypass valve 7 is connected to the first outlet 62 of the humidifier 6; the cathode outlet 15 of the fuel cell stack 10 is connected to the second inlet 63 of the humidifier 6; the second outlet 64 of the humidifier 6 is connected to the cathode outlet 15 of the fuel cell stack 10; and the second outlet 65 of the humidifier 6 is connected to the cathode outlet 15 of the fuel cell stack 10. Port 64 is connected to the outside through the back pressure valve 12; the impedance detection device 9 is connected to the fuel cell; the controller is connected to the bypass valve 7 and the impedance detection device 9; the temperature, humidity and pressure sensors may include three, two, one or more, wherein when there are three temperature, humidity and pressure sensors, temperature, humidity and pressure sensor 4 may be set downstream of the air flow device 2 and between the intercooler 5; temperature, humidity and pressure sensor 8 may be set between the first outlet of the humidifier 6 and the cathode inlet 14 of the fuel cell stack 10; temperature, humidity and pressure sensor 11 may be set between the second inlet of the humidifier 6 and the cathode outlet 15 of the fuel cell stack 10.

[0038] The air flow device 2 can also be an air pressure sensor. The controller can include a PID (Proportion Integration Differentiation) controller 13 and a fuel cell controller connected to the PID controller. The fuel cell controller can determine the required inlet air humidity according to the impedance detected by the impedance detection device 9, and the PID controller is used to control the opening of the bypass valve 7 according to the required inlet air humidity, so that the humidity of the air entering the stack reaches the required inlet air humidity. The opening of the bypass valve can be, for example, the range of angles that the bypass valve can rotate. In the case where the range of rotation angles of the bypass valve is 0°-90°, when the bypass valve is rotated to 0°, the opening of the bypass valve is the smallest or the bypass valve is closed, and when the bypass valve is rotated to 90°, the opening of the bypass valve is the largest, and vice versa.

[0039] When the fuel cell is running, the system 100 provides oxidant for the stack 10. The air passes through the air filter 1, the air flow device 2, the air compressor 3, the temperature and humidity pressure sensor 4, and the intercooler 5 in turn, and then flows through the humidifier 6 and / or the bypass valve 7 according to the opening of the bypass valve 7, passes through the temperature and humidity pressure sensor 8, and enters the stack 10 through the inlet of the stack. The tail gas after the reaction enters the humidifier 6, and then flows through the back pressure valve 12 and is discharged.

[0040] In order to maintain the humidity of the proton exchange membrane within a reasonable range, it is necessary to calculate the water content of the current proton exchange membrane according to the resistance value measured by the impedance detection device 9, and to adjust the opening of the humidifier dry side bypass valve 7 according to the water content and the optimal inlet air humidity value of the fuel cell proton exchange membrane under the current working condition, so as to adjust the humidity of the air entering the stack through the PID controller 13.

[0041] The following will be described with reference to Figures 2-6 The vehicle-mounted fuel cell air inlet humidity adjusting method provided by the embodiment of the present application is described.

[0042] As Figure 5 shown, the vehicle-mounted fuel cell air inlet humidity adjusting method provided by the embodiment of the present application includes the following steps:

[0043] Step S1: Obtain the temperature of the stack.

[0044] The temperature of the stack can be obtained by the stack temperature sensor 16 (as Figures 1-4 shown).

[0045] Step S2: Determine whether the temperature of the stack is greater than 0℃.

[0046] When the temperature of the stack is greater than 0℃, step S4 is performed.

[0047] When the temperature of the stack is less than 0℃, step S3 is performed: the opening of the bypass valve of the humidifier is adjusted to the maximum.

[0048] In step S2, when the temperature of the stack is less than 0℃, it indicates that the ambient temperature is low, and the stack is low-temperature purged by dry air, and when the temperature of the stack rises to 0℃, the stack is started normally, thereby the time of cold start of the stack can be shortened.

[0049] In step S3, the flow direction of the air into the stack is shown by the thick solid arrow. Figure 3 When the opening of the bypass valve 7 is adjusted to the maximum, because the pressure drop of the air flowing through the intake branch is much smaller than the pressure drop of the air flowing through the humidifier 6, the air into the stack is all through the intake branch, and the stack is low-temperature purged by dry air. After a period of time, for example, 10-20 minutes or shorter or longer, step S1 is performed until the temperature of the stack is greater than 0℃.

[0050] When the temperature of the stack is greater than 0℃, it indicates that the fuel cell can start to run, and the stack starts to work, and step S4 is performed: the stack impedance of the fuel cell and the working condition information are obtained.

[0051] The stack impedance of the fuel cell can be obtained by the impedance detection device 9, and the working condition information can include the power change value. Of course, the working condition information can also include the current or voltage.

[0052] Step S5: it is determined whether the working condition information changes. When the working condition information indicates that the working condition of the fuel cell changes, step S6 is performed.

[0053] The on-board fuel cell system involves multiple working conditions such as start-stop, overload and idle during the working process, and the requirements for the humidity of the intake air are different in different working conditions, therefore, it is necessary to determine whether the working condition changes according to the working condition information. In the embodiment of the application, when the working condition changes, it indicates that the current, voltage or power change value exceeds the corresponding preset value. For example, when the power change value is greater than 0.5% of the rated power, it indicates that the working condition changes.

[0054] Step S6: the membrane water content of the fuel cell is determined according to the stack impedance and the working temperature of the stack.

[0055] The working temperature of the stack can be obtained by the stack temperature sensor. When the working condition changes, the membrane water content of the fuel cell is determined according to the stack impedance and the working temperature of the stack, thereby the membrane water content of the fuel cell can be determined more accurately and quickly, and the air intake humidity can be adjusted quickly.

[0056] In step S6, the membrane water content λ can be determined according to the following formula: m :

[0057]

[0058]

[0059]

[0060] wherein R ohm is the ohmic resistance, t m is the proton exchange membrane thickness, s m is the membrane conductivity, b1, b2 are empirical parameters, T st is the stack operating temperature, l m is the membrane water content, a is the water activity.

[0061] Step S7: determining the air inlet humidity value H1 under the current working condition according to the corresponding relationship between the membrane water content and the cathode relative humidity.

[0062] The fuel cell has a corresponding relationship between the membrane water content and the cathode relative humidity RHc under different working conditions. Figure 6 is a schematic diagram of the corresponding relationship between the membrane water content and the cathode relative humidity under some working conditions of the vehicle-mounted fuel cell provided by the embodiment of the present application.

[0063] Step S8: determining the power change value AP according to the working condition information, and determining the humidification change value AH according to the corresponding relationship between the power change value AP and the humidification change value AH.

[0064] wherein the relationship between the power change value AP and the humidification change value AH is determined according to a large number of preliminary experiments, a corresponding relationship table is formed, and the table is written into the vehicle controller as the basis of the table lookup calculation. For example, the corresponding relationship between the power change value AP (for example, a decrease of 3 kW) and the humidification change value AH (corresponding to an increase of 3%) is obtained.

[0065] Step S9: adjusting the air inlet humidity according to the air inlet humidity value under the current working condition and the humidification change value.

[0066] In step S9, the following steps can be included:

[0067] Step S91: determining the actual air inlet humidity value according to the sum of the air inlet humidity value under the current working condition and the humidification change value.

[0068] In step S91, the sum H1+AH of the air inlet humidity value H1 and the humidification change value AH can be taken as the actual air inlet humidity value H2.

[0069] Step S92: comparing the actual air inlet humidity value H2 with the humidity adjustment range of the humidifier.

[0070] In step S92, the inlet air humidity adjustment range of the humidifier can be expressed as (Hmin, Hmax).

[0071] Step S93: Determine whether the actual inlet air humidity value is within the adjustment range.

[0072] When the actual inlet air humidity value is within the adjustment range, i.e., H2∈(Hmin, Hmax), i.e., the humidifier humidity adjustment minimum value Hmin≤the actual inlet air humidity value H2≤the humidifier humidity adjustment maximum value Hmax, step S95 is executed: adjust the opening of the bypass valve of the humidifier, and stabilize the inlet air humidity of the fuel cell stack at H2 by PID control.

[0073] As described in the above embodiments of the present application, the opening of the bypass valve can be, for example, the range of the angle that it can rotate. In the case where the range of the rotation angle of the bypass valve is 0°-90°, the opening of the bypass valve is minimum or the bypass valve is closed when the bypass valve is rotated to 0°, and the opening of the bypass valve is maximum when the bypass valve is rotated to 90°, and vice versa. When the actual inlet air humidity value is within the adjustment range, it means that it is most appropriate to maintain the required inlet air humidity value at the actual inlet air humidity value H2, and therefore, the opening of the bypass valve is adjusted larger or smaller by PID until the temperature and humidity pressure sensor detects that the inlet air humidity value is the actual inlet air humidity value H2.

[0074] In step S95, the inlet air flow direction is as shown by the thick solid arrow. Figure 4 The air flows through the humidifier 6 and the bypass valve 7, respectively, and the opening of the humidifier dry side bypass valve 7 is finely adjusted by the PID controller 13 to control the air amount flowing through the humidifier and the dry circuit, so that the inlet air humidity of the fuel cell stack is maintained within the appropriate range, and the overall performance of the fuel cell is improved.

[0075] When the actual inlet air humidity value is not within the adjustment range, step S94 is executed: determine whether the actual inlet air humidity value is greater than the humidifier humidity adjustment maximum value, i.e., determine whether H2 is greater than Hmax.

[0076] When the actual inlet air humidity value is greater than the humidifier humidity adjustment maximum value, i.e., H2>Hmax, step S96 is executed: close the bypass valve of the humidifier or adjust the opening of the bypass valve of the humidifier to the minimum.

[0077] In step S96, when the actual inlet air humidity value is greater than the humidifier humidity adjustment maximum value, it means that the inlet air humidity needs to be increased to make the inlet air humidity as required as much as possible. The inlet air flow direction is as shown by the thick solid arrow. Figure 2 The air flows through the humidifier 6 and the bypass valve 7, respectively, and the opening of the humidifier dry side bypass valve 7 is finely adjusted by the PID controller 13 to control the air amount flowing through the humidifier and the dry circuit, so that the inlet air humidity of the fuel cell stack is maintained within the appropriate range, and the overall performance of the fuel cell is improved. Figure 2 In this case, the bypass valve 7 of the humidifier is closed, and the air flows through the humidifier 6 only after flowing out of the intercooler 5, so that the air humidity is made as required as much as possible.

[0078] When the actual intake air humidity value H2 is less than the humidifier humidity adjustment minimum value Hmin, that is, H2 < Hmin, step S97 is executed: the opening of the bypass valve of the humidifier is adjusted to the maximum.

[0079] In step S97, the direction of the air flow into the stack is as shown by the thick solid arrow. Figure 3 When the actual intake air humidity value H2 is less than the humidifier humidity adjustment minimum value Hmin, the air flows through the bypass valve only after flowing out of the intercooler 5, and the humidity of the air is reduced as much as possible.

[0080] Step S10: Obtain the working condition information of the stack.

[0081] After step S9 is executed, the working condition information of the stack is further determined, and it is determined whether the working condition has changed.

[0082] Step S11: Determine whether the power change value indicated by the working information is greater than a preset percentage of the rated power.

[0083] When the power change value is greater than the preset percentage of the rated power, step S6 is executed.

[0084] When the power change value is less than or equal to the preset percentage of the rated power, the humidity regulation of the membrane is ended.

[0085] Through the above steps, the intake air humidity can be adjusted in real time according to the working condition information (for example, according to the power change value). When the adjusted working condition information indicates that the working condition has not changed, the humidity regulation of the membrane can be ended. When the adjusted working condition information indicates that the working condition has changed, the above steps are continued to be executed to adjust the intake air humidity until the requirement is met. Real-time closed-loop correction of the air intake stack humidity is realized, so that the membrane is kept within the target humidity range, thereby ensuring that the proton exchange membrane of the fuel cell stack operates at an appropriate working humidity.

[0086] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If there is a conflict between the definitions in the present application and those provided in the prior art, the definitions in the present application prevail. In addition, the terminology used in the present specification is for the purpose of describing the embodiments of the present application only and is not intended to be limiting of the present application.

[0087] The method and the device are based on the same concept, and since the principles of the method and the device for solving the problem are similar, the implementation of the device and the method can be referred to each other, and the repeated parts will not be described again.

[0088] The words "first", "second", "third", etc., or module A, module B, module C, and the like used in the whole application are only used to distinguish similar objects, and do not represent a specific order of the objects. It can be understood that the specific order or sequence can be interchanged as long as it is allowed.

[0089] In the whole application, the labels representing steps such as S10, S20, etc. do not necessarily mean that the steps are executed in this order, and the order of the steps can be interchanged or the steps can be executed simultaneously as long as it is allowed.

[0090] The term "comprising" used in the whole application should not be interpreted as being limited to the following listed content; it does not exclude other structural elements or steps. Therefore, it should be interpreted as specifying the existence of the mentioned technical features, whole, step or component, but does not exclude the existence or addition of one or more other technical features, whole, step or component and its group.

[0091] It can be understood that those skilled in the art can combine the features mentioned in one or more embodiments mentioned in the whole application with the features in other embodiments in any appropriate manner to implement the present application.

[0092] Note that the above is only the preferred embodiment of the present application and the technical principles used. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the technical concept of the present application, all of which belong to the protection scope of the present application.

Claims

1. A method for regulating the humidity of air intake in a vehicle-mounted fuel cell, characterized in that, This includes acquiring information such as the fuel cell stack impedance, stack operating temperature, and operating conditions. When the operating condition information indicates a change in the operating condition of the fuel cell, the membrane water content of the fuel cell is determined based on the stack impedance and the stack operating temperature. The operating condition information includes a power change value, and when the operating condition changes, the power change value exceeds a preset percentage of its corresponding preset value. Based on the correspondence between the membrane water content and the cathode relative humidity, the intake humidity value of the air under the current operating conditions is determined. The humidification change value is determined based on the correspondence between the power change value and the humidification change value. The intake humidity is adjusted based on the intake humidity value under the current operating conditions and the humidification change value. Specifically, determining the membrane water content of the fuel cell based on the stack impedance and the stack operating temperature includes: The water content of the membrane is determined according to the following formula: Among them, R oh, For ohmic impedance, t m σ is the thickness of the proton exchange membrane. m Where b1 and b2 are empirical parameters, and T is the membrane conductivity. st λ is the operating temperature of the fuel cell stack. m denoted as membrane water content, and 'a' as water activity.

2. The method according to claim 1, characterized in that, Adjusting the intake air humidity based on the current air humidity value and the humidification change value specifically includes: The sum of the intake humidity value of the air under the current operating conditions and the humidification change value is compared with the humidity adjustment range of the humidifier; When the above and the above are within the adjustment range, adjust the opening of the bypass valve of the humidifier so that the intake air humidity is the above and the above; When the sum is greater than the adjustment range, the bypass valve of the humidifier is closed; When the opening of the humidifier's bypass valve is less than the specified adjustment range, the opening of the humidifier's bypass valve is adjusted to the maximum.

3. The method according to claim 1, characterized in that, Based on the intake air humidity value under the current operating conditions and the humidification change value, the adjustment of the intake air humidity further includes: Obtain the operating condition information of the fuel cell stack; When the power change value is greater than a preset percentage of the rated power, repeat the above steps.

4. The method according to claim 1, characterized in that, The preset percentage is 0.4% to 0.8%.

5. The method according to claim 1, characterized in that, Before obtaining the fuel cell stack impedance, stack operating temperature, and operating condition information, the following steps are also included: Obtain the fuel cell stack operating temperature; The above steps are performed when the operating temperature of the fuel cell stack is greater than 0°C; When the operating temperature of the fuel cell stack is less than 0°C, adjust the opening of the bypass valve of the humidifier to the maximum.

6. A vehicle-mounted fuel cell air intake humidity control system, characterized in that, include: The system includes an air filter, an air compressor, an intercooler, a humidifier, a bypass valve, a fuel cell, a controller, and an impedance detection device. The fuel cell has a stack. The outlet of the air filter is connected to the inlet of the air compressor; the outlet of the air compressor is connected to the inlet of the intercooler; the outlet of the intercooler is connected to the first inlet of the humidifier; the first outlet of the humidifier is connected to the cathode inlet of the fuel cell stack; one end of the bypass valve is connected to the outlet of the intercooler; the other end of the bypass valve is connected to the first outlet of the humidifier; the cathode outlet of the fuel cell stack is connected to the second inlet of the humidifier; the second outlet of the humidifier is connected to the outside; the impedance detection device is connected to the fuel cell. The controller is connected to the bypass valve and the impedance detection device, and is used to control the opening degree of the bypass valve by the adjustment method according to any one of claims 1-5.

7. The system according to claim 6, characterized in that, The controller includes a PID controller and a fuel cell controller.

8. The system according to claim 6, characterized in that, Also includes: Multiple temperature, humidity, and pressure sensors and a back pressure valve are provided. The multiple temperature, humidity, and pressure sensors are respectively disposed between the air compressor and the intercooler, between the first outlet of the humidifier and the cathode inlet of the fuel cell stack, and between the cathode outlet of the fuel cell stack and the second inlet of the humidifier. The back pressure valve is connected to the second outlet of the humidifier.

9. The system according to claim 6, characterized in that, Also includes: An air flow device or an air pressure sensor, wherein one end of the air flow device or the air pressure sensor is connected to the outlet of the air filter, and the other end of the air flow device or the air pressure sensor is connected to the inlet of the air compressor.

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