Discharge flow control method and device of air discharge loop and fuel cell system

Abstract

The invention discloses a discharge flow control method and device of an air discharge loop and a fuel cell system. The method comprises the following steps: determining a corresponding relation between a first index and a second index of the fuel cell system; wherein the first index comprises the rotating speed of an air compressor, the opening degree of a back pressure valve and the opening degree of a discharge valve, and the second index comprises the in-pile flow, in-pile pressure and discharge flow of air; according to the target in-pile flow, the target in-pile pressure and the corresponding relation of the fuel cell system, the target air compressor rotating speed, the target back pressure valve opening degree and the target discharge valve opening degree are determined; the fuel cell system is controlled to operate at the target air compressor rotating speed, the target back pressure valve opening degree and the target discharge valve opening degree; and adjusting the opening degree of the target discharge valve according to the actual electric pile current and the target electric pile current in the operation process of the fuel cell system so as to control the discharge flow of the air discharge loop. According to the scheme, the discharge flow of the air discharge loop can be accurately controlled on the basis of not increasing a flow meter.

Description

Technical Field

[0001] The present application belongs to the field of fuel cell technology, and in particular, relates to a leakage flow control method and device for an air leakage circuit, and a fuel cell system. Background Art

[0002] Under low-temperature cold start conditions, fuel cell systems often use an air undersupply scheme, causing an "oxygen starvation" phenomenon, thereby increasing the self-heating of the stack, improving the cold start rate of the fuel cell system, and increasing the cold start success rate.

[0003] Air shortage can be solved by controlling the opening of the relief valve after the air compressor outlet. A part of the air can be bypassed through the relief valve to reduce the air flow entering the fuel cell stack. Figure 1 FIG. 2 shows a schematic diagram of the structure of the air subsystem of the fuel cell system in some embodiments. Figure 1 As shown in FIG. 1 , the air subsystem includes an air main flow circuit and an air leakage circuit. When the leakage valve in the air leakage circuit is opened, part of the air flowing out of the intercooler outlet will not pass through the humidifier and the fuel cell stack, but will directly flow to the expander inlet through the leakage valve. The larger the opening of the leakage valve, the more air flow will be bypassed, and the less air flow will actually enter the fuel cell stack.

[0004] In order to reduce the number of parts, increase volumetric power density and reduce costs, fuel cell systems usually do not add new flow meters to the air leakage circuit. The leakage flow rate of air in the air leakage circuit is often an unknown number, and it is difficult to accurately determine the air flow entering the fuel cell stack, which seriously affects the calibration efficiency of the fuel cell system under cold start conditions. Summary of the invention

[0005] The embodiments of the present application provide a leakage flow control method, device and fuel cell system for an air leakage circuit, which can accurately control the leakage flow of the air leakage circuit to a certain extent without adding a flow meter, thereby improving the calibration efficiency of the fuel cell system under cold start conditions.

[0006] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0007] According to a first aspect of an embodiment of the present application, a leakage flow control method of an air leakage circuit is provided, which is applied to a fuel cell system, wherein the fuel cell system includes an air mainstream circuit, an air leakage circuit and a fuel cell stack, the air mainstream circuit includes an air compressor and a back pressure valve, and the air leakage circuit includes a leakage valve, and the method includes:

[0008] Determine a correspondence between a first indicator and a second indicator of the fuel cell system; wherein the first indicator includes an air compressor speed, a back pressure valve opening, and a discharge valve opening, and the second indicator includes an air inlet flow rate, an inlet pressure, and a discharge flow rate;

[0009] Determine the target air compressor speed, the target back pressure valve opening and the target relief valve opening according to the target stack flow rate, the target stack pressure and the corresponding relationship of the fuel cell system;

[0010] Controlling the fuel cell system to operate at a target air compressor speed, a target back pressure valve opening, and a target drain valve opening;

[0011] According to the actual stack current and the target stack current during the operation of the fuel cell system, the target leakage valve opening is adjusted to control the leakage flow of the air leakage circuit.

[0012] In some embodiments, the air mainstream circuit further includes an expander, and determining the corresponding relationship between the first indicator and the second indicator of the fuel cell system includes:

[0013] Set the air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow and relief flow;

[0014] Determining whether to reset the leakage flow rate according to a first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate and a second total pressure drop of the air leakage circuit at the leakage flow rate;

[0015] Under the condition that it is determined that the leakage flow rate is not to be reset, the inlet pressure of the first expander is determined according to the air compressor speed and the air compressor inlet flow rate;

[0016] According to the inlet pressure of the first expander, determining whether to reset the inlet flow of the air compressor;

[0017] In the case that the air compressor inlet flow is determined not to be reset, the difference between the air compressor inlet flow and the leakage flow is determined as the stack inlet flow;

[0018] Determine the air inlet pressure according to the air compressor speed and air compressor inlet flow rate;

[0019] The set air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow and discharge flow, and the determined stacking pressure and stacking flow are stored correspondingly, and the steps of setting the air compressor speed, back pressure valve opening, discharge valve opening, air compressor inlet flow and discharge flow are returned to obtain the corresponding relationship between the first indicator and the second indicator.

[0020] In some embodiments, judging whether to reset the leakage flow rate according to a first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate and a second total pressure drop of the air leakage circuit at the leakage flow rate includes:

[0021] The total pressure drop difference is obtained by subtracting the second total pressure drop of the air leakage circuit at the leakage flow rate from the first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate;

[0022] When the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is less than the first preset value, it is determined that there is no need to reset the leakage flow rate;

[0023] When the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is greater than or equal to the first preset value, it is determined that the leakage flow rate needs to be reset.

[0024] In some embodiments, the air mainstream circuit further includes an air filter and an intercooler, and the first expander inlet pressure is determined according to the air compressor speed and the air compressor inlet flow rate, including:

[0025] Obtain the air filter pressure drop and intercooler pressure drop under atmospheric pressure and air compressor inlet flow;

[0026] Determine the compressor pressure ratio according to the compressor speed and compressor inlet flow rate;

[0027] Subtract the air filter resistance from the atmospheric pressure to get the compressor inlet pressure;

[0028] Multiply the compressor inlet pressure by the compressor pressure ratio to get the compressor outlet pressure;

[0029] The inlet pressure of the first expander is obtained by subtracting the intercooler pressure drop and the second total pressure drop from the air compressor outlet pressure.

[0030] In some embodiments, the air mainstream circuit further includes a humidifier and a stack entry shut-off valve, and the air entry pressure is determined according to the air compressor speed and the air compressor inlet flow, including:

[0031] Obtain the dry side pressure drop of the humidifier and the pressure drop of the stop valve entering the stack at the air compressor inlet flow rate;

[0032] The air inlet pressure is obtained by subtracting the intercooler pressure drop, the dry side pressure drop of the humidifier and the pressure drop of the stack inlet stop valve from the air compressor outlet pressure.

[0033] In some embodiments, the air mainstream circuit further includes mixing, and determining whether to reset the air compressor inlet flow rate according to the first expander inlet pressure includes:

[0034] Obtain the mixed pressure drop at the air compressor inlet flow rate;

[0035] Determine the inlet pressure of the second expander according to the inlet flow rate of the air compressor, the mixed pressure drop and the speed of the air compressor;

[0036] Subtract the inlet pressure of the second expander from the inlet pressure of the first expander to obtain a pressure difference;

[0037] When the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is less than the second preset value, it is determined that there is no need to reset the inlet flow rate of the air compressor;

[0038] When the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is greater than or equal to the second preset value, it is determined that the air compressor inlet flow rate needs to be reset.

[0039] In some embodiments, determining the inlet pressure of the second expander according to the air compressor inlet flow, the mixed pressure drop and the air compressor speed includes:

[0040] The sum of the mixed pressure drop and the atmospheric pressure is determined as the expander outlet pressure;

[0041] Determine the expansion ratio of the expander according to the air compressor speed and the air compressor inlet flow rate;

[0042] The expansion ratio is multiplied by the expander outlet pressure to obtain the second expander inlet pressure.

[0043] According to a second aspect of an embodiment of the present application, a leakage flow control device for an air leakage circuit is provided, comprising a processor and a memory, wherein the memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of any method of the first aspect described above are implemented.

[0044] According to the third aspect of an embodiment of the present application, a fuel cell system is provided, comprising an air mainstream circuit, an air leakage circuit, a fuel cell stack and a leakage flow control device of the above-mentioned air leakage circuit, wherein the air mainstream circuit comprises an air compressor and a back pressure valve, and the air leakage circuit comprises a leakage valve.

[0045] According to the fourth aspect of the embodiments of the present application, a computer-readable storage medium is provided, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of any method of the first aspect described above.

[0046] In the present application, by determining the correspondence between the first indicator and the second indicator of the fuel cell system; wherein the first indicator includes the air compressor speed, the back pressure valve opening and the leakage valve opening, and the second indicator includes the air inflow, inflow pressure and leakage flow; according to the target inflow, target inflow pressure and the correspondence of the fuel cell system, the target air compressor speed, target back pressure valve opening and target leakage valve opening are determined; the fuel cell system is controlled to operate at the target air compressor speed, target back pressure valve opening and target leakage valve opening; according to the actual stack current and the target stack current during the operation of the fuel cell system, the target leakage valve opening is adjusted to control the leakage flow of the air leakage circuit. The above scheme can accurately control the leakage flow of the air leakage circuit by adjusting the leakage valve opening without adding a flow meter, thereby improving the calibration efficiency of the fuel cell system under cold start conditions.

[0047] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0049] Figure 1 A schematic diagram of the structure of an air subsystem of a fuel cell system in some embodiments is shown;

[0050] Figure 2 A schematic flow chart showing a method for controlling a leakage flow rate of an air leakage circuit in some embodiments is shown;

[0051] Figure 3 A detailed schematic diagram of step 201 is shown;

[0052] Figure 4 A block diagram of a leakage flow control device of an air leakage circuit in one embodiment is shown;

[0053] Figure 5 A schematic structural diagram of a leakage flow control device of an air leakage circuit in one embodiment is shown.

[0054] Description of Figure Numbers:

[0055] 1-air filter, 2-air flow meter, 3-air compressor, 4-intercooler, 5-humidifier, 6-stack inlet stop valve, 7-stack outlet stop valve, 8-water-gas separator, 9-back pressure valve, 10-expander, 11-mixed discharge, 12-leakage valve, 13-fuel cell stack. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0057] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0058] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0059] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0060] It should also be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the objects used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those shown or described.

[0061] In order to make those skilled in the art better understand the present application, firstly, Figure 1 The application scenarios involved in this application are briefly described.

[0062] like Figure 1 As shown, the air subsystem includes an air mainstream circuit and an air leakage circuit. The air mainstream circuit includes an air filter 1, an air flow meter 2, an air compressor 3, an intercooler 4, a humidifier 5, an inlet shut-off valve 6, an outlet shut-off valve 7, a water-gas separator 8, a back pressure valve 9, an expander 10 and a mixed discharge 11, etc. The air leakage circuit includes a leakage valve 12. After the leakage valve 12 is opened, a part of the air flowing out of the outlet of the intercooler 4 will not pass through the humidifier 5 and the stack 13, but will directly flow to the inlet of the expander 10 through the leakage valve 12. The larger the opening of the leakage valve 12, the more the bypass air flow, and the less the actual air flow entering the stack 13. Since a flow meter is usually not designed in the air leakage circuit, it is difficult to accurately control the leakage flow of air in the air leakage circuit.

[0063] The embodiment of the present application forms a corresponding relationship by first accurately estimating the leakage flow rate of the air leakage circuit, the air inlet flow rate and the inlet pressure under different operating conditions (air compressor speed, back pressure valve opening and leakage valve opening). In the controller of the fuel cell system, the target air compressor speed, target back pressure valve opening and target leakage valve opening can be found in the corresponding relationship according to the target inlet flow rate and the target inlet pressure, and the operation of the fuel cell system can be controlled by these three target parameters. The target leakage valve opening is adjusted by the actual stack current during operation to achieve the purpose of accurate control of the leakage flow rate. This method can avoid adding a flow meter in the air leakage circuit, reduce costs and improve calibration efficiency.

[0064] Figure 2 FIG. 2 is a flow chart showing a method for controlling the leakage flow rate of an air leakage circuit in some embodiments. Figure 2 As shown, a leakage flow control method for an air leakage circuit is provided, which can be applied to Figure 1 The air subsystem of the fuel cell system shown, the method may include the following steps:

[0065] Step 201, determining a correspondence between a first indicator and a second indicator of a fuel cell system; wherein the first indicator includes an air compressor speed, a back pressure valve opening, and a leakage valve opening, and the second indicator includes an air inlet flow rate, an inlet pressure, and a leakage flow rate;

[0066] Step 202, determining a target air compressor speed, a target back pressure valve opening, and a target drain valve opening according to a target stack flow rate, a target stack pressure, and a corresponding relationship of the fuel cell system;

[0067] Step 203, controlling the fuel cell system to operate at a target air compressor speed, a target back pressure valve opening, and a target drain valve opening;

[0068] Step 204, adjusting the target leakage valve opening according to the actual stack current and the target stack current during the operation of the fuel cell system to control the leakage flow of the air leakage circuit.

[0069] In the implementation process, the inflow flow, inflow pressure and discharge flow under different air compressor speeds, back pressure valve openings and discharge valve openings can be calculated in advance, and then the air compressor speed, back pressure valve opening and discharge valve opening are matched with the inflow flow, inflow pressure and discharge flow to form a MAP table. Table 1 shows an example of a MAP table:

[0070] Table 1

[0071] Air compressor speed Drain valve opening Back pressure valve opening Air compressor inlet flow Discharge flow Pile pressure Into the pile flow rpm ％ ％ g / s g / s kPa g / s 20000 10 10 10.00 10.00 100.76 0.00 20000 20 10 10.00 10.00 100.76 0.00 20000 20 20 25.00 24.38 103.60 0.63 20000 10 30 10.00 6.00 100.62 4.00 20000 20 30 32.50 29.25 104.35 3.25 30000 10 10 30.00 22.50 109.02 7.50 30000 20 10 60.00 49.50 113.71 10.50 30000 20 20 70.00 47.25 113.49 22.75 40000 10 10 75.00 40.78 125.64 34.22 40000 20 10 97.50 67.64 126.41 29.86 40000 10 20 90.00 38.81 125.95 51.19 40000 20 20 105.00 64.97 125.50 40.03 40000 10 30 97.50 37.48 125.49 60.02 40000 20 30 108.75 61.17 124.82 47.58 40000 10 40 98.75 37.03 125.37 61.72 40000 20 40 110.00 61.88 124.63 48.13 50000 10 10 106.25 54.79 143.11 51.46 50000 20 10 130.63 89.40 142.40 41.23 50000 20 20 140.00 81.38 140.32 58.63 50000 20 30 145.63 76.45 138.77 69.17 50000 20 40 147.50 74.67 138.20 72.83

[0072] When it is necessary to control the discharge flow, the MAP table is obtained, and the target air compressor speed, target back pressure valve opening and target discharge valve opening corresponding to the target inlet flow and target inlet pressure are searched in the MAP table, and the three target parameters found are used as feedforward control data to control the air compressor, back pressure valve and discharge valve.

[0073] During the operation of the fuel cell system, the target leakage valve opening can be adjusted by feedback control methods (such as PID, etc.) according to the actual stack current and the target stack current. When the actual stack current is greater than the target stack current, it means that the amount of air provided to the stack by the air mainstream circuit is too small, and the leakage flow of the air leakage circuit is too large. At this time, the controller can send a leakage valve opening control signal to reduce the target leakage valve opening to reduce the leakage flow; when the actual stack current is less than the target stack current, it means that the leakage flow of the air leakage circuit is too small. At this time, the controller can send a leakage valve opening control signal to increase the target leakage valve opening to increase the leakage flow.

[0074] The embodiment of the present application determines the corresponding relationship between the first indicator and the second indicator of the fuel cell system; wherein the first indicator includes the air compressor speed, the back pressure valve opening and the leakage valve opening, and the second indicator includes the air inflow, inflow pressure and leakage flow; according to the target inflow, target inflow pressure and corresponding relationship of the fuel cell system, the target air compressor speed, target back pressure valve opening and target leakage valve opening are determined; the fuel cell system is controlled to operate at the target air compressor speed, target back pressure valve opening and target leakage valve opening; according to the actual stack current and target stack current during the operation of the fuel cell system, the target leakage valve opening is adjusted to control the leakage flow of the air leakage circuit. The above scheme can accurately control the leakage flow of the air leakage circuit by adjusting the leakage valve opening without adding a flow meter, thereby improving the calibration efficiency of the fuel cell system under cold start conditions.

[0075] In some embodiments, step 201 may include the following steps: setting the air compressor speed, the back pressure valve opening, the relief valve opening, the air compressor inlet flow and the leakage flow; judging whether to reset the leakage flow according to the first total pressure drop of the air mainstream circuit at the air compressor inlet flow and the second total pressure drop of the air leakage circuit at the leakage flow; determining the first expander inlet pressure according to the air compressor speed and the air compressor inlet flow when it is determined not to reset the leakage flow; judging whether to reset the air compressor inlet flow according to the first expander inlet pressure; Under the condition that it is determined that the air compressor inlet flow rate will not be reset, the difference between the air compressor inlet flow rate and the leakage flow rate is determined as the stack inlet flow rate; the air stack inlet pressure is determined according to the air compressor speed and the air compressor inlet flow rate; the set air compressor speed, back pressure valve opening, leakage valve opening, air compressor inlet flow rate and leakage flow rate, as well as the determined stack inlet pressure and stack inlet flow rate are stored correspondingly, and the step of setting the air compressor speed, back pressure valve opening, leakage valve opening, air compressor inlet flow rate and leakage flow rate is returned to obtain the corresponding relationship between the first indicator and the second indicator.

[0076] During the implementation process, the air compressor speed, back pressure valve opening, and relief valve opening can be set according to the actual working conditions; the air compressor inlet flow can be set according to the aerodynamic performance data under the air compressor speed, the minimum value is the surge flow, and the maximum value is the blocking flow; the relief flow can be set according to the air compressor inlet flow, and its value range should be 0 to 100% of the air compressor inlet flow.

[0077] Based on the flow-pressure drop test data of the fuel cell system components, the pressure drop of all components in the air mainstream circuit under the air compressor inlet flow can be calculated, including the air filter pressure drop, intercooler pressure drop, inlet shut-off valve pressure drop, humidifier dry side pressure drop, outlet shut-off valve pressure drop, humidifier wet side pressure drop, water-gas separator pressure drop, pipeline pressure drop of the air mainstream circuit, etc. All the calculated pressure drops are summed to obtain the first total pressure drop.

[0078] Similarly, based on the flow-pressure drop test data of the fuel cell system components, the pressure drop of all components in the air leakage circuit under the leakage flow rate can be calculated, including the leakage valve pressure drop and the pipeline pressure drop of the air leakage circuit. All calculated pressure drops are summed to obtain the second total pressure drop.

[0079] In some embodiments, the first total pressure drop of the mainstream air circuit at the air compressor inlet flow rate can be subtracted from the second total pressure drop of the air leakage circuit at the leakage flow rate to obtain a total pressure drop difference; when the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is less than a first preset value, it is determined that there is no need to reset the leakage flow rate; when the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is greater than or equal to the first preset value, it is determined that the leakage flow rate needs to be reset.

[0080] Taking the first preset value of 10e-4 as an example, when the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is less than 10e-4, it indicates that the set leakage flow is relatively accurate and does not need to be reset. Otherwise, it indicates that the set leakage flow has a large error and needs to be reset. The second total pressure drop of the air leakage circuit under the newly set leakage flow needs to be recalculated, and then it is determined whether the leakage flow needs to be reset until the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is less than 10e-4. In this way, the leakage flow can be determined more accurately.

[0081] In some embodiments, the air filter pressure drop and intercooler pressure drop under atmospheric pressure and air compressor inlet flow can be obtained; the air compressor pressure ratio is determined according to the air compressor speed and the air compressor inlet flow; the air filter flow resistance is subtracted from the atmospheric pressure to obtain the air compressor inlet pressure; the air compressor inlet pressure is multiplied by the air compressor pressure ratio to obtain the air compressor outlet pressure; the intercooler pressure drop and the second total pressure drop are subtracted from the air compressor outlet pressure to obtain the first expander inlet pressure.

[0082] During the implementation process, the air compressor pressure ratio can be obtained by interpolating the air compressor speed and the air compressor inlet flow rate according to the aerodynamic performance data of the air compressor.

[0083] In some embodiments, the mixed pressure drop under the air compressor inlet flow can be obtained; the second expander inlet pressure is determined according to the air compressor inlet flow, the mixed pressure drop and the air compressor speed; the first expander inlet pressure is subtracted from the second expander inlet pressure to obtain the pressure difference; when the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is less than a second preset value, it is determined that the air compressor inlet flow does not need to be reset; when the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is greater than or equal to the second preset value, it is determined that the air compressor inlet flow needs to be reset.

[0084] During the implementation process, the sum of the mixed pressure drop and the atmospheric pressure can be determined as the expander outlet pressure; the expansion ratio of the expander can be determined based on the air compressor speed and the air compressor inlet flow; the expansion ratio is multiplied by the expander outlet pressure to obtain the second expander inlet pressure.

[0085] Among them, the expansion ratio of the expander can be calculated by table interpolation based on the air compressor speed and the air compressor inlet flow rate.

[0086] Taking the second preset value of 10e-4 as an example, when the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is less than 10e-4, it indicates that the set air compressor inlet flow is relatively accurate and does not need to be reset. Otherwise, it indicates that the set air compressor inlet flow has a large error and needs to be reset. The air compressor inlet flow and the leakage flow need to be reset, and the subsequent steps are re-executed until the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is less than 10e-4. In this way, the corresponding relationship between the air compressor speed, the back pressure valve opening, the leakage valve opening, the air compressor inlet flow and the leakage flow can be accurately determined.

[0087] After determining the corresponding relationship between the air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow and leakage flow, the air inlet flow can also be calculated, and the humidifier dry side pressure drop and the inlet stop valve pressure drop under the air compressor inlet flow can be obtained; the air inlet pressure is obtained by subtracting the intercooler pressure drop, the humidifier dry side pressure drop and the inlet stop valve pressure drop from the air compressor outlet pressure. In this way, the corresponding relationship between the air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow, leakage flow, inlet pressure and inlet flow can be established, and the corresponding relationship can be referred to in Table 1 above.

[0088] Figure 3 FIG. 2 shows a detailed schematic diagram of step 201. Figure 3 As shown, step 201 includes the following steps:

[0089] Step 301, setting the air compressor speed, back pressure valve opening, and drain valve opening;

[0090] Step 302, setting the air compressor inlet flow rate;

[0091] Step 303, setting the leakage flow rate;

[0092] Step 304, calculate the pressure drop of the air filter, the pressure drop of the intercooler, the pressure drop of the inlet stop valve, the pressure drop of the dry side of the humidifier, the pressure drop of the outlet stop valve, the pressure drop of the wet side of the humidifier, the pressure drop of the water-gas separator, the pressure drop of the pipeline of the air mainstream circuit, etc., and sum up all the calculated pressure drops to obtain the first total pressure drop ΔP of the air mainstream circuit main ;

[0093] Step 305: Calculate the pressure drop of the relief valve and the pressure drop of the pipeline of the air relief circuit, and sum them to obtain the second total pressure drop ΔP of the air relief circuit. brance ;

[0094] Step 306, determine whether |(ΔP main -ΔP brance ) / ΔP main |<10e-4;

[0095] Step 307, calculate the first expander inlet pressure P according to the air compressor speed and the air compressor inlet flow rate T,in ;

[0096] Step 308, calculating the expander outlet pressure;

[0097] Step 309, calculate the expansion ratio of the expander, and calculate the outlet pressure P of the second expander according to the outlet pressure of the expander and the expansion ratio. T,in,new ;

[0098] Step 310, determine whether |(P T,in -P T,in,new ) / P T,in |<10e-4;

[0099] Step 311, calculating the flow rate and pressure of the stack;

[0100] Step 312, outputting the corresponding relationship among the air compressor speed, the back pressure valve opening, the relief valve opening, the relief flow rate, the stack flow rate and the stack pressure.

[0101] The embodiment of the present application is based on the characteristic data and theoretical formula of each component in the fuel cell system. By setting a double iterative cycle process, the air compressor inlet flow is first assumed, and then the leakage flow is assumed. According to the flow-pressure drop test data of each component and the characteristic curve data of the air compressor, the first total pressure drop ΔP of the air mainstream circuit is calculated respectively. main The second total pressure drop of the air leakage circuit ΔP brance When the difference between the two is small enough, it means that the assumed value of the leakage flow is equal to the actual value. After the previous iteration cycle is completed, the inlet pressure P of the first expander can be obtained. T,in , and then calculate the inlet pressure P of the second expander according to the characteristic curve data of the expander and the flow-pressure drop test data of the tail row. T,in,new When the difference between the two is small enough, it means that the assumed value of the compressor inlet flow is equal to the actual value, and the second-level iteration loop ends, and the calculated values ​​under different parameter conditions are output to form the corresponding relationship between the compressor speed, the opening of the relief valve, the opening of the back pressure valve, the leakage flow, the inlet flow and the inlet pressure. In this way, the leakage flow under different compressor speeds, the opening of the relief valve and the opening of the back pressure valve can be accurately obtained.

[0102] The following describes an embodiment of the device of the present application, which can be used to execute the leakage flow control method of the air leakage circuit in the above embodiment of the present application. For details not disclosed in the embodiment of the device of the present application, please refer to the embodiment of the leakage flow control method of the air leakage circuit in the above embodiment of the present application.

[0103] Figure 4 FIG. 1 is a block diagram of a leakage flow control device for an air leakage circuit in one embodiment. Figure 4 As shown, the leakage flow control device of the air leakage circuit of the embodiment of the present application includes: a correspondence determination module 401, which is used to determine the correspondence between the first indicator and the second indicator of the fuel cell system; wherein the first indicator includes the air compressor speed, the back pressure valve opening and the leakage valve opening, and the second indicator includes the air inflow flow, the inflow pressure and the leakage flow; a control parameter determination module 402, which is used to determine the target air compressor speed, the target back pressure valve opening and the target leakage valve opening according to the target inflow flow, the target inflow pressure and the correspondence of the fuel cell system; a system operation control module 403, which is used to control the fuel cell system to operate with the target air compressor speed, the target back pressure valve opening and the target leakage valve opening; a leakage flow adjustment module 404, which is used to adjust the target leakage valve opening according to the actual stack current and the target stack current during the operation of the fuel cell system to control the leakage flow of the air leakage circuit.

[0104] In some embodiments, the corresponding relationship determination module 401 can also be used to set the air compressor speed, the back pressure valve opening, the relief valve opening, the air compressor inlet flow and the leakage flow; determine whether to reset the leakage flow according to the first total pressure drop of the air mainstream circuit at the air compressor inlet flow and the second total pressure drop of the air leakage circuit at the leakage flow; if it is determined that the leakage flow is not to be reset, determine the first expander inlet pressure according to the air compressor speed and the air compressor inlet flow; determine whether to reset the air compressor inlet flow according to the first expander inlet pressure. quantity; when it is determined that the air compressor inlet flow rate is not to be reset, the difference between the air compressor inlet flow rate and the leakage flow rate is determined as the stack inlet flow rate; the air stack inlet pressure is determined according to the air compressor speed and the air compressor inlet flow rate; the set air compressor speed, back pressure valve opening, leakage valve opening, air compressor inlet flow rate and leakage flow rate, as well as the determined stack inlet pressure and stack inlet flow rate are stored correspondingly, and the steps of setting the air compressor speed, back pressure valve opening, leakage valve opening, air compressor inlet flow rate and leakage flow rate are returned to obtain the corresponding relationship between the first indicator and the second indicator.

[0105] In some embodiments, the correspondence determination module 401 can also be used to subtract the second total pressure drop of the air leakage circuit at the leakage flow rate from the first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate to obtain a total pressure drop difference; when the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is less than a first preset value, it is determined that there is no need to reset the leakage flow rate; when the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is greater than or equal to the first preset value, it is determined that the leakage flow rate needs to be reset.

[0106] In some embodiments, the correspondence determination module 401 can also be used to obtain the air filter pressure drop and intercooler pressure drop under atmospheric pressure and air compressor inlet flow; determine the air compressor pressure ratio according to the air compressor speed and the air compressor inlet flow; subtract the air filter flow resistance from the atmospheric pressure to obtain the air compressor inlet pressure; multiply the air compressor inlet pressure by the air compressor pressure ratio to obtain the air compressor outlet pressure; subtract the intercooler pressure drop and the second total pressure drop from the air compressor outlet pressure to obtain the first expander inlet pressure.

[0107] In some embodiments, the correspondence determination module 401 can also be used to obtain the dry side pressure drop of the humidifier and the pressure drop of the stack shut-off valve under the air compressor inlet flow; subtract the intercooler pressure drop, the dry side pressure drop of the humidifier and the pressure drop of the stack shut-off valve from the air compressor outlet pressure to obtain the air inlet pressure.

[0108] In some embodiments, the correspondence determination module 401 can also be used to obtain the mixed pressure drop under the air compressor inlet flow; determine the second expander inlet pressure according to the air compressor inlet flow, the mixed pressure drop and the air compressor speed; subtract the second expander inlet pressure from the first expander inlet pressure to obtain the pressure difference; when the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is less than the second preset value, it is determined that the air compressor inlet flow does not need to be reset; when the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is greater than or equal to the second preset value, it is determined that the air compressor inlet flow needs to be reset.

[0109] In some embodiments, the correspondence determination module 401 can also be used to determine the sum of the mixed pressure drop and the atmospheric pressure as the expander outlet pressure; determine the expansion ratio of the expander according to the air compressor speed and the air compressor inlet flow; multiply the expansion ratio by the expander outlet pressure to obtain the second expander inlet pressure.

[0110] Based on the same inventive concept, the embodiment of the present application also provides a leakage flow control device for an air leakage circuit, referring to Figure 5 , shows a schematic diagram of the structure of the leakage flow control device of the air leakage circuit in the embodiment of the present application, the leakage flow control device of the air leakage circuit includes one or more memories 504, one or more processors 502 and at least one computer program (computer program instruction) stored in the memory 504 and executable on the processor 502, and the processor 502 implements the method described above when executing the computer program.

[0111] Among them, Figure 5In the embodiment of the present invention, a bus architecture (represented by bus 500) is shown, which may include any number of interconnected buses and bridges, and bus 500 links various circuits including one or more processors represented by processor 502 and memory represented by memory 504. Bus 500 may also link various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. Bus interface 505 provides an interface between bus 500 and receiver 501 and transmitter 503. Receiver 501 and transmitter 503 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 502 is responsible for managing bus 500 and general processing, while memory 504 may be used to store data used by processor 502 when performing operations.

[0112] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method as described above.

[0113] Based on the same inventive concept, an embodiment of the present application provides a computer program product, including a computer program. When the computer program product is executed by a processor, it prompts the processor to implement the steps of the method as described above.

[0114] Based on the same inventive concept, an embodiment of the present application provides a fuel cell system, including an air mainstream circuit, an air leakage circuit, a fuel cell stack and a leakage flow control device of the above-mentioned air leakage circuit, wherein the air mainstream circuit includes an air compressor and a back pressure valve, and the air leakage circuit includes a leakage valve.

[0115] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on a computer-readable medium or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of the present application and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these. In addition, each functional unit may be integrated into a processing unit, each unit may exist physically separately, or two or more units may be integrated into one unit.

[0116] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0117] The units described as separate components may or may not be physically separated, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed in multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0118] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly or all or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc., which can store computer program instructions.

[0119] The above description is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A method for controlling the leakage flow rate of an air leakage circuit, applied to a fuel cell system, characterized in that: The fuel cell system comprises an air mainstream circuit, an air leakage circuit and a fuel cell stack, the air mainstream circuit comprises an air compressor and a back pressure valve, the air leakage circuit comprises a leakage valve, and the method comprises: Determine a correspondence between a first indicator and a second indicator of the fuel cell system; wherein the first indicator includes an air compressor speed, a back pressure valve opening, and a leakage valve opening, and the second indicator includes an air inlet flow rate, an inlet pressure, and a leakage flow rate; Determining a target air compressor speed, a target back pressure valve opening, and a target drain valve opening according to a target stack flow rate, a target stack pressure, and the corresponding relationship of the fuel cell system; Controlling the fuel cell system to operate at the target air compressor speed, target back pressure valve opening, and target drain valve opening; The target leakage valve opening is adjusted according to the actual stack current and the target stack current during the operation of the fuel cell system to control the leakage flow of the air leakage circuit.

2. The method for controlling the leakage flow rate of an air leakage circuit according to claim 1, characterized in that: The main air flow circuit further includes an expander, and the determining the corresponding relationship between the first indicator and the second indicator of the fuel cell system includes: Set the air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow and relief flow; Determining whether to reset the leakage flow rate according to a first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate and a second total pressure drop of the air leakage circuit at the leakage flow rate; In the case where it is determined that the leakage flow rate is not to be reset, determining the inlet pressure of the first expander according to the air compressor speed and the air compressor inlet flow rate; determining whether to reset the air compressor inlet flow rate according to the first expander inlet pressure; In the case where it is determined that the air compressor inlet flow rate is not to be reset, the difference between the air compressor inlet flow rate and the leakage flow rate is determined as the stack inlet flow rate; Determining the stack inlet pressure of air according to the air compressor rotation speed and the air compressor inlet flow rate; The set air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow and leakage flow, and the determined stacking pressure and stacking flow are correspondingly stored, and the step of setting the air compressor speed, back pressure valve opening, relief valve opening, air compressor inlet flow and leakage flow is returned to obtain the corresponding relationship between the first indicator and the second indicator.

3. The method for controlling the leakage flow rate of an air leakage circuit according to claim 2, characterized in that: The determining whether to reset the leakage flow rate according to a first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate and a second total pressure drop of the air leakage circuit at the leakage flow rate comprises: The total pressure drop difference is obtained by subtracting the second total pressure drop of the air leakage circuit at the leakage flow rate from the first total pressure drop of the air mainstream circuit at the air compressor inlet flow rate; When the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is less than a first preset value, determining that the leakage flow rate does not need to be reset; When the ratio of the absolute value of the total pressure drop difference to the first total pressure drop is greater than or equal to the first preset value, it is determined that the leakage flow rate needs to be reset.

4. The method for controlling the leakage flow rate of an air leakage circuit according to claim 2, characterized in that: The air mainstream circuit further includes an air filter and an intercooler. The determining of the first expander inlet pressure according to the air compressor speed and the air compressor inlet flow rate includes: Obtaining atmospheric pressure, air filter pressure drop and intercooler pressure drop at the air compressor inlet flow rate; Determining the air compressor pressure ratio according to the air compressor speed and the air compressor inlet flow rate; Subtract the air filter flow resistance from the atmospheric pressure to obtain the air compressor inlet pressure; Multiplying the air compressor inlet pressure by the air compressor pressure ratio to obtain the air compressor outlet pressure; The first expander inlet pressure is obtained by subtracting the intercooler pressure drop and the second total pressure drop from the air compressor outlet pressure.

5. The method for controlling the leakage flow rate of an air leakage circuit according to claim 4, characterized in that: The air mainstream circuit further includes a humidifier and a stack entry shut-off valve. The determining of the stack entry pressure of the air according to the air compressor speed and the air compressor inlet flow rate includes: Obtaining the dry side pressure drop of the humidifier and the pressure drop of the stack stop valve at the air compressor inlet flow rate; The air inlet pressure is obtained by subtracting the intercooler pressure drop, the humidifier dry side pressure drop and the inlet stop valve pressure drop from the air compressor outlet pressure.

6. The method for controlling the leakage flow rate of an air leakage circuit according to claim 4, characterized in that: The main air flow circuit also includes mixed discharge, and determining whether to reset the air compressor inlet flow rate according to the inlet pressure of the first expander includes: Obtaining the mixed pressure drop at the air compressor inlet flow rate; Determining the inlet pressure of the second expander according to the air compressor inlet flow, the mixed pressure drop and the air compressor speed; Subtracting the inlet pressure of the second expander from the inlet pressure of the first expander to obtain a pressure difference; When the ratio of the absolute value of the pressure difference to the inlet pressure of the first expander is less than a second preset value, it is determined that there is no need to reset the inlet flow rate of the air compressor; When the ratio of the absolute value of the pressure difference to the first expander inlet pressure is greater than or equal to the second preset value, it is determined that the air compressor inlet flow needs to be reset.

7. The method for controlling the leakage flow rate of an air leakage circuit according to claim 6, characterized in that: Determining the inlet pressure of the second expander according to the air compressor inlet flow, the mixed pressure drop and the air compressor speed includes: The sum of the mixed pressure drop and the atmospheric pressure is determined as the expander outlet pressure; Determining the expansion ratio of the expander according to the air compressor speed and the air compressor inlet flow rate; The expansion ratio is multiplied by the expander outlet pressure to obtain the second expander inlet pressure.

8. A leakage flow control device for an air leakage circuit, comprising a processor and a memory, characterized in that: The memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A fuel cell system, characterized in that: It comprises an air mainstream circuit, an air leakage circuit, a fuel cell stack and a leakage flow control device of the air leakage circuit according to claim 8, wherein the air mainstream circuit comprises an air compressor and a back pressure valve, and the air leakage circuit comprises a leakage valve.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, which, when executed by a processor, prompt the processor to implement the steps of the method according to any one of claims 1 to 7.

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