Humidity control method and device of fuel cell system

Abstract

The invention provides a humidity control method and device for a fuel cell system, and relates to the technical field of fuel cell energy management.The method comprises the steps that the target humidity range of a proton exchange membrane of a fuel cell in the fuel cell system is compared with the current water content, and whether the proton exchange membrane is in a target working state or not is judged; if yes, determining in-stack air target humidity corresponding to the proton exchange membrane in the target humidity range according to a corresponding relation between the water content of the proton exchange membrane and in-stack air humidity of the fuel cell; the opening degree of a bypass valve is controlled based on the reactor inlet air target humidity; wherein the bypass valve is arranged at a cathode outlet of the fuel cell, so that the technical problem that the fuel cell system is relatively poor in application stability is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell energy management, and in particular to a humidity control method and device for a fuel cell system. Background Art

[0002] The operation of the proton exchange membrane of the vehicle fuel cell system requires a certain amount of water. Insufficient water content will lead to excessive internal resistance of the fuel cell, high heat generation and low efficiency; while excessive water content will lead to symptoms such as "flooding". Therefore, the control of the water content of the cathode of the fuel cell is more important for the application safety of the vehicle fuel cell system.

[0003] The inventors have found that currently, the bypass valve is generally set at the cathode intake end of the fuel cell. This design will directly cause fluctuations in the gas state of the intake when the valve opening changes. This fluctuation will affect the electrochemical reaction process of the fuel cell and increase the instability of the fuel cell system. Summary of the invention

[0004] The object of the present invention is to provide a humidity control method and device for a fuel cell system, so as to alleviate the technical problem of poor application stability of the fuel cell system.

[0005] In a first aspect, an embodiment of the present invention provides a humidity control method for a fuel cell system, comprising:

[0006] comparing a target humidity range of a proton exchange membrane of a fuel cell in the fuel cell system with a current moisture content to determine whether the proton exchange membrane is in a target working state;

[0007] If yes, then determining the target humidity of the air entering the fuel cell stack corresponding to the proton exchange membrane within the target humidity range according to the corresponding relationship between the water content of the proton exchange membrane and the humidity of the air entering the fuel cell stack;

[0008] Based on the target humidity of the air entering the stack, the opening of the bypass valve is controlled; wherein the bypass valve is arranged at the cathode outlet of the fuel cell.

[0009] In combination with the first aspect, an embodiment of the present invention provides a first possible implementation of the first aspect, wherein the step of controlling the opening of the bypass valve based on the target humidity of the incoming air includes:

[0010] The bypass air mass corresponding to the bypass valve is calculated based on the target humidity of the incoming air, the dry side parameter and the wet side parameter of the humidifier; wherein the bypass air mass is the mass of the air discharged from the cathode of the fuel cell without passing through the wet side of the humidifier under the control of the bypass valve after the incoming air passes through the dry side of the humidifier and enters the cathode of the fuel cell;

[0011] The opening of the bypass valve is controlled according to the bypass air mass corresponding to the bypass valve.

[0012] In combination with the first aspect, an embodiment of the present invention provides a second possible implementation of the first aspect, wherein the step of calculating the bypass air mass corresponding to the bypass valve based on the target humidity of the incoming air, the dry side parameters and the wet side parameters of the humidifier includes:

[0013] The dry side parameters and wet side parameters of the humidifier are obtained by sensors arranged at the cathode inlet and cathode outlet of the fuel cell; wherein the dry side of the humidifier is connected to the cathode inlet of the fuel cell, and the wet side of the humidifier is connected to the cathode outlet of the fuel cell, and the dry side parameters include the cathode inlet humidity of the fuel cell, the cathode inlet temperature and pressure of the fuel cell, the dry side saturated vapor pressure, the water vapor mass flow rate in the dry side of the humidifier, and the volume of the dry side of the humidifier, and the wet side parameters include the wet side saturated vapor pressure, the wet side mass flow rate, and the water vapor mass flow rate in the wet side of the humidifier;

[0014] The bypass air mass corresponding to the bypass valve is calculated based on the dry side parameters and wet side parameters of the humidifier, the gas constant of water vapor, the cathode stoichiometric ratio, and the water transfer efficiency of the dry side and the wet side of the humidifier.

[0015] In combination with the first aspect, an embodiment of the present invention provides a third possible implementation of the first aspect, wherein the step of controlling the opening of the bypass valve according to the bypass air mass corresponding to the bypass valve includes:

[0016] Dividing the opening of the bypass valve into a preset number of opening intervals;

[0017] Establishing a mapping relationship between different bypass air masses of the bypass valve and the opening range;

[0018] Based on the mapping relationship and the bypass air mass currently corresponding to the bypass valve, a current opening degree of the bypass valve is determined.

[0019] In combination with the first aspect, the embodiment of the present invention provides a fourth possible implementation of the first aspect, wherein the method further includes:

[0020] If the humidity of the proton exchange membrane is higher or lower than the target working state, a new target humidity of the air entering the stack is calculated according to the target humidity of the air entering the stack and the PID percentage; wherein the PID percentage is determined according to the difference between the target humidity range of the proton exchange membrane and the current water content and the PI coefficient.

[0021] In combination with the first aspect, the embodiment of the present invention provides a fifth possible implementation of the first aspect, wherein the method further includes:

[0022] When the humidity of the proton exchange membrane is higher or lower than the target working state, the opening of the bypass valve is controlled according to the new target humidity of the incoming air, and a counting operation is performed on the counter;

[0023] determining again at a preset time interval whether the proton exchange membrane is in a target working state;

[0024] If the counter continuously performs counting operations at low humidity for a number of times reaching a first preset value, the output power of the fuel cell system is reduced;

[0025] If the counter continuously performs counting operations at high humidity for a number of times reaching a second preset value, the output power of the fuel cell system is restored.

[0026] In combination with the first aspect, an embodiment of the present invention provides a sixth possible implementation of the first aspect, wherein, before comparing the target humidity range of the proton exchange membrane of the fuel cell in the fuel cell system with the current water content to determine whether the proton exchange membrane is in the target working state, the step further includes:

[0027] Determining a target humidity range corresponding to a proton exchange membrane of the fuel cell system according to a current output power of the fuel cell system;

[0028] Based on the ohmic impedance of a fuel cell in the fuel cell system, a current water content of the proton exchange membrane is determined.

[0029] In a second aspect, an embodiment of the present invention further provides a humidity control device for a fuel cell system, comprising:

[0030] A judgment module, comparing a target humidity range of a proton exchange membrane of a fuel cell in the fuel cell system with a current moisture content, to judge whether the proton exchange membrane is in a target working state;

[0031] The determination module determines, if yes, the target humidity of the air entering the fuel cell stack corresponding to the proton exchange membrane within the target humidity range according to the corresponding relationship between the water content of the proton exchange membrane and the humidity of the air entering the fuel cell stack;

[0032] A control module controls the opening of a bypass valve based on the target humidity of the air entering the stack; wherein the bypass valve is arranged at the cathode outlet of the fuel cell.

[0033] In a third aspect, an embodiment provides an electronic device, including a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the computer program, the steps of the method described in any of the aforementioned implementation methods are implemented.

[0034] In a fourth aspect, an embodiment provides a machine-readable storage medium, wherein the machine-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the steps of the method described in any one of the aforementioned implementations.

[0035] The embodiment of the present invention provides a humidity control method and device for a fuel cell system, wherein the control of the humidity corresponding to the target working state of the proton exchange membrane of the fuel cell is achieved by allowing the incoming air humidified by a humidifier to enter the fuel cell cathode; currently, a bypass valve is provided at the cathode outlet of the fuel cell, and by adjusting the opening of the bypass valve, that is, adjusting the proportion of the humidified air at the cathode outlet that enters the bypass valve without passing through the humidifier under the opening, the humidification effect of the humidifier is controlled to ensure that the incoming air humidified by the humidifier can reasonably humidify the proton exchange membrane, so that the proton exchange membrane of the fuel cell is stably maintained within the target humidity range. At this time, the fuel cell can reach the target working state, thereby ensuring the reliability of the fuel cell application.

[0036] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A flow chart of a humidity control method for a fuel cell system provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of an application architecture of a humidity control method for a fuel cell system provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the PID percentage principle provided by an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of the functional modules of a humidity control device for a fuel cell system provided by an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of the hardware architecture of an electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] Currently, a bypass valve is usually designed at the cathode inlet end, and the inlet of the humidifier is connected to the cathode inlet of the fuel cell stack. By controlling the opening degree of the bypass valve, the ratio of humid air to dry air is adjusted, and finally the water content of the gas mixture of dry air and humid air is controlled.

[0046] This humidity adjustment method poses relatively high requirements and challenges for cathode inlet control. Since the traditional bypass valve is arranged at the inlet end, the change in the opening degree of the valve will directly cause fluctuations in the state of the inlet gas, which will affect the electrochemical reaction process of the fuel cell stack, thereby increasing the instability of the system.

[0047] Based on this, a humidity control method and device for a fuel cell system provided by an embodiment of the present invention can adjust the proportion of air entering the wet side of the humidifier by controlling the opening degree of the bypass valve arranged at the cathode outlet, and then realize the humidity of the air entering the dry side of the humidifier at the next time, which can ensure that the humidity of the proton exchange membrane of the fuel cell is in the target working state.

[0048] For easy understanding of this embodiment, first, a humidity control method for a fuel cell system disclosed in an embodiment of the present invention will be introduced in detail. This method can be applied to intelligent control devices such as fuel cell controllers, host computers, and servers.

[0049] Figure 1 A flowchart of a humidity control method for a fuel cell system provided by an embodiment of the present invention.

[0050] Refer to Figure 1 , the humidity control method of the fuel cell system is mainly implemented through the following steps, including:

[0051] Step S102: Compare the target humidity range of the proton exchange membrane of the fuel cell in the fuel cell system with the current water content to determine whether the proton exchange membrane is in the target working state.

[0052] Among them, the target working state can be understood as the humidity state that can make the proton exchange membrane present an ideal working state.

[0053] Before step S102, it also includes the steps of obtaining the target humidity range and the current water content of the proton exchange membrane:

[0054] Step 1.1): Determine the target humidity range corresponding to the proton exchange membrane of the fuel cell system according to the current output power of the fuel cell system.

[0055] Among them, the required target humidity of the fuel cell is different at different powers. The demand humidity correspondence table (ControlMap1) of the proton exchange membrane of the fuel cell at different powers can be determined through experiments, calculations, analyses, etc. In practical applications, the fuel cell controller (FCU) detects the current output power of the fuel cell system, and then according to this output power, uses ControlMap1 to find out the target humidity range Setpoint_Hu corresponding to the proton exchange membrane at the current power.

[0056] Step 1.2): Determine the current water content of the proton exchange membrane based on the ohmic impedance of the fuel cell in the fuel cell system; the specific formula is as follows:

[0057]

[0058]

[0059] σ 303K (λ)=0.005193λ m -0.00326(3)

[0060]

[0061] Among them, R ohm is the ohmic impedance, t m is the thickness of the proton exchange membrane, σ m is the membrane conductivity, T is the operating temperature of the stack, λ m is the current water content of the proton exchange membrane, and a is the water activity.

[0062] By using the above formulas (1)-(4), after the ohmic impedance of the fuel cell is diagnosed, the current water content of the proton exchange membrane can be calculated. It should be noted that the ohmic impedance is not detected in real time, and the ohmic impedance detection can be performed at intervals of a preset time t1; that is, when the time from the last ohmic impedance detection is greater than t1, the current ohmic impedance detection is performed. Generally, the t1 time can be set according to actual conditions, such as 5 minutes, 9 minutes, 10 minutes, 11 minutes, 15 minutes, etc., preferably about 10 minutes.

[0063] Step S104: If yes, then according to the corresponding relationship between the water content of the proton exchange membrane and the air humidity entering the fuel cell stack, the target humidity of the air entering the fuel cell stack corresponding to the proton exchange membrane within the target humidity range is determined.

[0064] It should be noted that the corresponding relationship between the humidity of the air entering the fuel cell and the water content of the proton exchange membrane (ControlMap2) can be obtained in advance through experiments, calculations, etc. When the target humidity range Setpoint_Hu of the proton exchange membrane is determined based on the above step embodiment, the target humidity SetpointHu_ of the air entering the fuel cell can be obtained by looking up the table according to ControlMap2. Ca .

[0065] Step S106: Control the opening of the bypass valve based on the target humidity of the air entering the stack.

[0066] Among them, the bypass valve is arranged at the cathode outlet of the fuel cell. According to the target humidity of the air entering the stack, it is known how to adjust the opening of the bypass valve at the cathode outlet, so as to control the proportion of humid air entering the wet side of the humidifier, and then adjust the humidity of the cathode intake air through the dry side of the humidifier, so as to ensure that the proton exchange membrane of the fuel cell presents the target working state based on the cathode intake air with this humidity.

[0067] In a preferred embodiment of actual application, the control of humidity corresponding to the target working state of the proton exchange membrane of the fuel cell is achieved by entering the stack air humidified by a humidifier through the cathode of the fuel cell; currently, a bypass valve is set at the cathode outlet of the fuel cell, and by adjusting the opening of the bypass valve, that is, adjusting the proportion of humid air at the cathode outlet entering the bypass valve without passing through the humidifier under the opening, the humidification effect of the humidifier is controlled to ensure that the stack air humidified by the humidifier can reasonably humidify the proton exchange membrane, so that the proton exchange membrane of the fuel cell is stably maintained within the target humidity range. At this time, the fuel cell can reach the target working state, ensuring the reliability of the fuel cell application.

[0068] On the basis of the above-mentioned embodiment, in order to further ensure the reliability of fuel cell application, if the current proton exchange membrane is not in the target working state, that is, compared with the proton exchange membrane in the target working state, the membrane will be drier or wetter, then it is still necessary to adopt a precise control strategy to achieve fuel cell humidity control; the method also includes:

[0069] Step 2.1), if the humidity of the proton exchange membrane is higher or lower than the target working state, a new target humidity of the air entering the stack is calculated based on the target humidity of the air entering the stack and the PID percentage.

[0070] First, based on the comparison result of the current water content λm calculated in the above embodiment and the target humidity range Setpoint_Hu corresponding to the proton exchange membrane, the current humidity state of the proton exchange membrane is determined; when Setpoint_Hu>λm, the membrane is in a relatively dry state; when Setpoint_Hu<λm, the membrane is in a relatively wet state. If the two are equal, the proton exchange membrane is in a suitable target working state.

[0071] Secondly, if the current proton exchange membrane is in a dry state or a wet state, the target humidity of the incoming air that will be humidified by the proton exchange membrane can be appropriately increased or decreased. The control measures are as follows: if the membrane is judged to be wet, the target humidity of the incoming air SetpointHu_ Ca The value decreases, and the calculation formula is as follows:

[0072] SetpointHu ca New=SetpointHu Ca +SetpointHu Ca *PID Prec (5)

[0073] Among them, SetpointHu Ca is the target humidity of the air entering the pile, SetpointHu ca New is the new target humidity of the incoming air calculated after the membrane wetness is determined. PID_Prec represents the PID percentage, which is calculated by the PID controller. The PID percentage is determined based on the difference between the target humidity range of the proton exchange membrane and the current moisture content, as well as the proportional P coefficient and the integral I coefficient; specifically, Figure 3 As shown:

[0074] Generally, the P parameter and the I parameter are defined as positive numbers. Then, when the membrane is dry, the target humidity range Setpoint_Hu of the membrane needs to be greater than the current moisture content λm. The inputs to the P controller and the I controller are positive numbers, and PID_Prec is a positive number, so that the new target humidity of the incoming air calculated by the above formula (5) gradually increases until the membrane state is normal or the coefficient of PID_Prec reaches the set upper limit.

[0075] Due to the effect of the integral I controller, PID_Prec will continue to increase. At this time, it is necessary to add an upper limit to the PID_Prec value. First, it is to avoid serious overshoot action. Second, it is necessary to consider the humidification capacity of the humidifier. If the upper limit of this value is not limited, the humidification capacity of the humidifier may have reached the upper limit, but the new target humidity of the incoming air calculated by formula (5) has been rising. At this time, the actual physical performance cannot be increased, resulting in calculation failure.

[0076] Similarly, when the membrane is wet, the target humidity range Setpoint_Hu of the membrane needs to be less than the current moisture content λm. The input to the P controller and the I controller is a negative number, and PID_Prec is a negative number, so that the new target humidity of the incoming air calculated by the above formula (5) gradually decreases until the state of the membrane is normal or the coefficient of PID_Prec reaches the set lower limit; the setting principle of the PID_Prec lower limit is the same as the setting principle of the PID_Prec upper limit, which will not be repeated here. The upper and lower limits of PID_Prec need to consider the physical properties of the humidifier, the selection of P parameters and I parameters, and the actual application scenario, and comprehensively consider and specify the value.

[0077] In some embodiments, according to the target humidity of the incoming air determined in the above embodiments, the opening of the bypass valve is precisely controlled to ensure that the proton exchange membrane is in the target working state in real time; specifically, step S106 can be implemented by the following steps, including:

[0078] Step 3.1), based on the target humidity of the air entering the stack, the dry side parameters and the wet side parameters of the humidifier, calculate the bypass air mass corresponding to the bypass valve.

[0079] Among them, Figure 2An application architecture shown is used as an example for explanation, in which a filter S1, an air compressor S2, and an intercooler S3 are connected in sequence, and an end (outlet end) of the intercooler S3 away from the air compressor is connected to the dry side inlet end of the humidifier S4, and a stack entry temperature sensor and a stack entry temperature and pressure sensor are arranged between the dry side outlet end of the humidifier S4 and the cathode inlet of the fuel cell S5. A mass pressure temperature humidity flowmeter and a back pressure valve S6 are arranged in sequence at the cathode outlet of the fuel cell S5, and an end (outlet end) of the back pressure valve S6 away from the mass pressure temperature humidity flowmeter is connected to the wet side inlet end of the humidifier S4, an inlet end of the bypass valve S7 is arranged between the mass pressure temperature humidity flowmeter and the inlet end of the back pressure valve S6, and an outlet end of the bypass valve S7 is connected to the wet side outlet end of the humidifier S4; an inlet end of the bypass valve S9 is arranged between the air compressor S2 and the intercooler S3, and an outlet end of the bypass valve S9 is connected to the wet side outlet end of the humidifier S4.

[0080] The filter S1 filters the air entering the fuel cell system. The air compressor S2 draws the filtered air from the outside into the system and compresses the air for use by the fuel cell. The intercooler S3 cools the compressed gas from the air compressor. The humidifier S4 is used to increase the humidity of the air that is about to enter the fuel cell, i.e., the humidity of the air entering the stack.

[0081] Specifically, after the air entering the stack is humidified on the dry side of the humidifier, it enters the cathode of the fuel cell S5 through the stack temperature sensor and the stack temperature and pressure sensor. The air at the cathode outlet passes through the mass pressure temperature humidity flow meter. Under the control of the bypass valve S7, the air ratio of the gas discharged from the cathode of the fuel cell passing through the bypass valve S7 and the air ratio of the air passing through the back pressure valve S6 entering the wet side of the humidifier is determined respectively;

[0082] Among them, the back pressure valve S6 is used to provide back pressure for the cathode side of the entire fuel cell system; the bypass valve S7 is responsible for diverting the air entering the humidifier and is also one of the main components for realizing humidification control; the bypass valve S9 is used to protect the air compressor.

[0083] In practical applications, the dry side parameters and wet side parameters of the humidifier are obtained by sensors arranged at the cathode inlet and cathode outlet of the fuel cell; the dry side parameters include the inlet humidity of the cathode inlet of the fuel cell collected by the inlet temperature sensor, the cathode inlet temperature and pressure of the fuel cell collected by the inlet temperature and pressure sensor, the dry side saturated vapor pressure and the mass flow rate of water vapor in the dry side of the humidifier and the volume of the dry side of the humidifier, and the wet side parameters include the saturated vapor pressure, mass flow rate and the mass flow rate of water vapor in the wet side of the humidifier;

[0084] Exemplarily, based on the dry side parameters and wet side parameters of the humidifier, the gas constant of water vapor, the cathode stoichiometric ratio, and the water transfer efficiency of the dry side and the wet side of the humidifier, the bypass air mass corresponding to the bypass valve is calculated, and the bypass air mass can be understood as the air mass passing through the bypass valve S7.

[0085] It can be assumed that the air humidity at the dry side outlet of the humidifier is similar to the air humidity inside the dry side of the humidifier, and the bypass air quality corresponding to the bypass valve is determined according to the following formula for calculating the air humidity inside the dry side of the humidifier:

[0086]

[0087]

[0088]

[0089] Where R is the gas constant of water vapor, T dry is the temperature of the dry side of the humidifier collected by the stack temperature and pressure sensor at the cathode inlet of the fuel cell, P sat It is in T dry Saturated vapor pressure at temperature, V dry is the volume of the dry side of the humidifier, which needs to be determined according to the physical parameters of the humidifier, λ is the cathode stoichiometric ratio, Hu is the air humidity at the cathode inlet of the fuel cell collected by the stack humidity sensor at the cathode inlet of the fuel cell, and P in is the stack pressure collected by the stack temperature and pressure sensor at the cathode inlet of the fuel cell, P satin is the saturated vapor pressure at the temperature displayed by the mass pressure temperature humidity flow meter, m ca is the mass flow rate collected by the mass pressure temperature humidity flowmeter, m wet is the water vapor mass flow rate in the wet side of the humidifier, m dry is the mass flow rate of water vapor in the dry side of the humidifier. η is the water transfer efficiency of the humidifier and is a physical parameter of the humidifier. It is a coefficient used to replace the coefficients representing the same parameters and has no actual physical meaning. value is the air mass bypassed by the bypass valve S7. This value is used to characterize the function of the bypass valve opening and the pressure difference on both sides of the bypass valve. value Control the opening of the bypass valve.

[0090] Step 3.2), controlling the opening of the bypass valve according to the bypass air mass corresponding to the bypass valve.

[0091] In practical applications, the opening of the bypass valve can be first divided into a preset number of opening intervals; then a mapping relationship between different bypass air masses of the bypass valve and the opening intervals is established; and then based on the mapping relationship and the bypass air mass currently corresponding to the bypass valve, the current opening of the bypass valve is determined.

[0092] For example, the valve opening angle can be pre-divided into 100 intervals, corresponding to 0%-100%, and the opening of the bypass valve to be controlled can be determined based on the mapping relationship between the percentage and the bypass air quality. value Increased, then increase the bypass valve opening, if the calculated m value If it decreases, the opening of the bypass valve will be reduced accordingly.

[0093] It can be understood that, based on the valve opening, the proportion of wet side air entering the bypass valve and the humidifier can be controlled respectively, thereby adjusting the humidification effect of the humidifier; for example, the proportion of wet side air entering the humidifier is reduced through the bypass valve, and the volume of wet air in the humidifier is reduced, and its humidification ability for the air entering the dry side will be weakened; conversely, the proportion of wet side air entering the humidifier is increased through the bypass valve, and the volume of wet air in the humidifier is increased, and its humidification ability for the air entering the dry side will be enhanced; the embodiment of the present invention achieves reasonable control of the humidity of the proton exchange membrane by changing the humidification effect of the air entering the humidifier.

[0094] In some embodiments, in order to further ensure the application reliability of the fuel cell, the humidity control effect of the fuel cell is also verified. If the control effect does not meet expectations, the following control methods can be used:

[0095] Step 4.1), when the humidity of the proton exchange membrane is higher or lower than the target working state, the opening of the bypass valve is controlled according to the new target humidity of the incoming air, and the counter is counted.

[0096] Here, first determine whether it is invalid. When the state of the diagnostic film is dry (or wet, only the dry state is used for explanation here), the counter counts.

[0097] Step 4.2), judging again whether the proton exchange membrane is in the target working state according to the preset time interval.

[0098] The preset time interval is the time after the ohmic impedance detection interval t1 is shortened, that is, the detection time interval is shortened to determine again whether the proton exchange membrane is in the target working state.

[0099] Step 4.3), if the counter continuously performs counting operations for low humidity for a number of times reaching a first preset value, the output power of the fuel cell system is reduced.

[0100] Step 4.4), if the counter continuously performs counting operations at high humidity for a number of times reaching a second preset value, the output power of the fuel cell system is restored.

[0101] When the counter finds that the detection state is dry for n consecutive times, it is determined that the current fuel cell humidity control method of the embodiment of the present invention is invalid. At this time, the output power of the fuel cell system begins to be reduced, and the specific power reduction range is determined according to ControlMap1. At this time, the detection of ohmic impedance, that is, the humidity state detection of the proton exchange membrane continues; as another optional embodiment, if the proton exchange membrane is in the target working state, the counter can also be counted; when the counter detects that the proton exchange membrane is in the target working state for m consecutive times, the output power of the fuel cell system is restored.

[0102] It should be noted that step 4.1) to step 4.3) are not executed every time the machine is powered on, and the above process is executed only when the failure diagnosis determines that the machine is a failure.

[0103] Compared with the traditional solution, the embodiment of the present invention controls the moisture on the wet side of the humidifier by changing the setting position of the bypass valve, thereby changing the humidification effect from controlling the ratio of dry and wet air entering the stack to controlling the humidity of the air entering the stack, thereby achieving the purpose of controlling the humidity of the proton exchange membrane of the fuel cell system.

[0104] In some embodiments, Figure 4 As shown, an embodiment of the present invention further provides a humidity control device for a fuel cell system, comprising:

[0105] A judgment module, comparing a target humidity range of a proton exchange membrane of a fuel cell in the fuel cell system with a current moisture content, to judge whether the proton exchange membrane is in a target working state;

[0106] The determination module determines, if yes, the target humidity of the air entering the fuel cell stack corresponding to the proton exchange membrane within the target humidity range according to the corresponding relationship between the water content of the proton exchange membrane and the humidity of the air entering the fuel cell stack;

[0107] A control module controls the opening of a bypass valve based on the target humidity of the air entering the stack; wherein the bypass valve is arranged at the cathode outlet of the fuel cell.

[0108] In some embodiments, the control module is further specifically used to calculate the bypass air mass corresponding to the bypass valve based on the target humidity of the incoming air, the dry side parameters and the wet side parameters of the humidifier; wherein the bypass air mass is the mass of air discharged from the cathode of the fuel cell without passing through the wet side of the humidifier under the control of the bypass valve after the incoming air passes through the dry side of the humidifier and enters the cathode of the fuel cell; and the opening of the bypass valve is controlled according to the bypass air mass corresponding to the bypass valve.

[0109] In some embodiments, the control module is further specifically used to obtain the dry side parameters and wet side parameters of the humidifier through sensors arranged at the cathode inlet and cathode outlet of the fuel cell; wherein the dry side of the humidifier is connected to the cathode inlet of the fuel cell, and the wet side of the humidifier is connected to the cathode outlet of the fuel cell, and the dry side parameters include the cathode inlet humidity of the fuel cell, the cathode inlet temperature and pressure of the fuel cell, the dry side saturated vapor pressure and the water vapor mass flow rate in the dry side of the humidifier and the volume of the dry side of the humidifier, and the wet side parameters include the wet side saturated vapor pressure, the wet side mass flow rate and the water vapor mass flow rate in the wet side of the humidifier; based on the dry side parameters and wet side parameters of the humidifier, as well as the gas constant of water vapor, the cathode stoichiometric ratio, and the water transfer efficiency of the dry side and the wet side of the humidifier, the bypass air mass corresponding to the bypass valve is calculated.

[0110] In some embodiments, the control module is further specifically used to divide the opening of the bypass valve into a preset number of opening intervals; establish a mapping relationship between different bypass air masses of the bypass valve and the opening intervals; and determine the current opening of the bypass valve based on the mapping relationship and the bypass air mass currently corresponding to the bypass valve.

[0111] In some embodiments, the control module is further specifically used to calculate a new target humidity of the air entering the stack according to the target humidity of the air entering the stack and the PID percentage if the humidity of the proton exchange membrane is higher or lower than the target working state; wherein the PID percentage is determined based on the difference between the target humidity range of the proton exchange membrane and the current water content and the PI coefficient.

[0112] In some embodiments, the control module is further specifically used to, when the humidity of the proton exchange membrane is higher or lower than the target working state, control the opening of the bypass valve according to the new target humidity of the incoming air, and perform counting operations on the counter; determine again whether the proton exchange membrane is in the target working state at a preset time interval; if the number of consecutive counting operations of the counter for low humidity reaches a first preset value, reduce the output power of the fuel cell system; if the number of consecutive counting operations of the counter for high humidity reaches a second preset value, restore the output power of the fuel cell system.

[0113] In some embodiments, before comparing the target humidity range and current water content of the proton exchange membrane of the fuel cell in the fuel cell system to determine whether the proton exchange membrane is in the target working state, the device is also used to determine the target humidity range corresponding to the proton exchange membrane of the fuel cell system based on the current output power of the fuel cell system; and determine the current water content of the proton exchange membrane based on the ohmic impedance of the fuel cell in the fuel cell system.

[0114] An embodiment of the present invention provides an electronic device for implementing an electronic device. In this embodiment, the electronic device may be, but is not limited to, a personal computer (PC), a laptop computer, a monitoring device, a server, or other computer device with analysis and processing capabilities.

[0115] As an exemplary embodiment, see Figure 5 The electronic device 110 includes a communication interface 111, a processor 112, a memory 113 and a bus 114. The processor 112, the communication interface 111 and the memory 113 are connected via the bus 114. The memory 113 is used to store a computer program that supports the processor 112 to execute the method. The processor 112 is configured to execute the program stored in the memory 113.

[0116] The machine-readable storage medium mentioned in this article can be any electronic, magnetic, optical or other physical storage device that can contain or store information, such as executable instructions, data, etc. For example, the machine-readable storage medium can be: RAM (Radom Access Memory), volatile memory, non-volatile memory, flash memory, storage drive (such as hard disk drive), any type of storage disk (such as CD, DVD, etc.), or similar storage medium, or a combination thereof.

[0117] The non-volatile medium may be a non-volatile memory, a flash memory, a storage drive (such as a hard drive), any type of storage disk (such as a CD, DVD, etc.), or a similar non-volatile storage medium, or a combination thereof.

[0118] It can be understood that the specific operation methods of each functional module in this embodiment can refer to the detailed description of the corresponding steps in the above method embodiment, and will not be repeated here.

[0119] The computer-readable storage medium provided in the embodiment of the present invention stores a computer program. When the computer program code is executed, the method described in any of the above embodiments can be implemented. For specific implementation, please refer to the method embodiment, which will not be described in detail here.

[0120] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0121] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0122] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0123] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, those of ordinary skill in the art should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed by the present invention, or can easily conceive of changes, or make equivalent replacements for some of the technical features therein. Such modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. A method for controlling humidity in a fuel cell system, It is characterized in that include: comparing a target humidity range of a proton exchange membrane of a fuel cell in the fuel cell system with a current moisture content to determine whether the proton exchange membrane is in a target working state; If yes, then determining the target humidity of the air entering the fuel cell stack corresponding to the proton exchange membrane within the target humidity range according to the corresponding relationship between the water content of the proton exchange membrane and the humidity of the air entering the fuel cell stack; Based on the target humidity of the air entering the stack, the opening of the bypass valve is controlled; wherein the bypass valve is arranged at the cathode outlet of the fuel cell.

2. The method according to claim 1, It is characterized in that The step of controlling the opening of the bypass valve based on the target humidity of the incoming air comprises: The bypass air mass corresponding to the bypass valve is calculated based on the target humidity of the incoming air, the dry side parameter and the wet side parameter of the humidifier; wherein the bypass air mass is the mass of the air discharged from the cathode of the fuel cell without passing through the wet side of the humidifier under the control of the bypass valve after the incoming air passes through the dry side of the humidifier and enters the cathode of the fuel cell; The opening of the bypass valve is controlled according to the bypass air mass corresponding to the bypass valve.

3. The method according to claim 2, It is characterized in that The step of calculating the bypass air mass corresponding to the bypass valve based on the target humidity of the incoming air, the dry side parameters and the wet side parameters of the humidifier comprises: The dry side parameters and wet side parameters of the humidifier are obtained by sensors arranged at the cathode inlet and cathode outlet of the fuel cell; wherein the dry side of the humidifier is connected to the cathode inlet of the fuel cell, and the wet side of the humidifier is connected to the cathode outlet of the fuel cell, and the dry side parameters include the cathode inlet humidity of the fuel cell, the cathode inlet temperature and pressure of the fuel cell, the dry side saturated vapor pressure, the water vapor mass flow rate in the dry side of the humidifier, and the volume of the dry side of the humidifier, and the wet side parameters include the wet side saturated vapor pressure, the wet side mass flow rate, and the water vapor mass flow rate in the wet side of the humidifier; The bypass air mass corresponding to the bypass valve is calculated based on the dry side parameters and wet side parameters of the humidifier, the gas constant of water vapor, the cathode stoichiometric ratio, and the water transfer efficiency of the dry side and the wet side of the humidifier.

4. The method according to claim 2, It is characterized in that The step of controlling the opening of the bypass valve according to the bypass air mass corresponding to the bypass valve comprises: Dividing the opening of the bypass valve into a preset number of opening intervals; Establishing a mapping relationship between different bypass air masses of the bypass valve and the opening range; Based on the mapping relationship and the bypass air mass currently corresponding to the bypass valve, a current opening degree of the bypass valve is determined.

5. The method according to claim 1, It is characterized in that The method further comprises: If the humidity of the proton exchange membrane is higher or lower than the target working state, a new target humidity of the air entering the stack is calculated according to the target humidity of the air entering the stack and the PID percentage; wherein the PID percentage is determined according to the difference between the target humidity range of the proton exchange membrane and the current water content and the PI coefficient.

6. The method according to claim 5, It is characterized in that The method further comprises: When the humidity of the proton exchange membrane is higher or lower than the target working state, the opening of the bypass valve is controlled according to the new target humidity of the incoming air, and a counting operation is performed on the counter; determining again at a preset time interval whether the proton exchange membrane is in a target working state; If the counter continuously performs counting operations at low humidity for a number of times reaching a first preset value, the output power of the fuel cell system is reduced; If the counter continuously performs counting operations at high humidity for a number of times reaching a second preset value, the output power of the fuel cell system is restored.

7. The method according to claim 1, It is characterized in that Before comparing the target humidity range of the proton exchange membrane of the fuel cell in the fuel cell system with the current water content to determine whether the proton exchange membrane is in the target working state, the method further includes: Determining a target humidity range corresponding to a proton exchange membrane of the fuel cell system according to a current output power of the fuel cell system; Based on the ohmic impedance of a fuel cell in the fuel cell system, a current water content of the proton exchange membrane is determined.

8. A humidity control device for a fuel cell system, It is characterized in that include: A judgment module, comparing a target humidity range of a proton exchange membrane of a fuel cell in the fuel cell system with a current moisture content, to judge whether the proton exchange membrane is in a target working state; The determination module determines, if yes, the target humidity of the air entering the fuel cell stack corresponding to the proton exchange membrane within the target humidity range according to the corresponding relationship between the water content of the proton exchange membrane and the humidity of the air entering the fuel cell stack; A control module controls the opening of a bypass valve based on the target humidity of the air entering the stack; wherein the bypass valve is arranged at the cathode outlet of the fuel cell.

9. An electronic device, It is characterized in that The method comprises a memory, a processor, and a program stored in the memory and capable of being run on the processor, wherein the processor implements the method according to any one of claims 1 to 7 when executing the program.

10. A computer-readable storage medium, It is characterized in that The readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 7 is implemented.

Images