CN109683093B - Fuel cell life prediction method, prediction device, and computer-readable storage medium - Google Patents
Fuel cell life prediction method, prediction device, and computer-readable storage medium Download PDFInfo
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Abstract
The application provides a fuel cell life prediction method, a prediction device and a computer readable storage medium. According to the fuel cell life prediction method, the fuel cell is classified according to the operating condition data of the fuel cell, key parameters in the fuel cell voltage decline model are obtained through data fitting, the fuel cell voltage decline model is constructed, the voltage decline condition of the fuel cell is estimated and predicted according to the fuel cell voltage decline model, meanwhile, the key parameters of the fuel cell voltage decline model are periodically corrected, the accuracy of the life estimation of the fuel cell can be ensured, and the accuracy of the estimation result is ensured.
Description
Technical Field
The present disclosure relates to the field of fuel cells, and more particularly, to a method and an apparatus for predicting a lifetime of a fuel cell, and a computer-readable storage medium.
Background
The fuel cell is widely concerned due to the advantages of high efficiency, cleanness, no pollution and the like, and has wide development prospect. One of the technical bottlenecks of the current vehicle proton exchange membrane fuel cell is its service life. In order to extend the service life of a fuel cell stack, it is necessary to be able to accurately estimate and predict the life thereof, which is also an important aspect in current research.
The service life of the fuel cell is measured by the output performance, the change of the internal structure of the fuel cell along with the use affects the performance decay rate to a certain extent, and especially the accelerated performance decay may occur in the middle and later periods of the service life of the fuel cell, so the service life prediction method of the fuel cell based on the performance decay should be continuously updated along with the actual use of the fuel cell. However, in the conventional methods for studying the performance degradation of the fuel cell, the method based on data analysis depends on the repeatability of the degradation mechanism, and when the operating condition of the fuel cell changes, the key parameters also need to be adjusted accordingly. Model-based methods are typically obtained by accelerated life testing, whereas the actual operating conditions of the fuel cell and the conditions of the accelerated life testing are different. The existing method is based on fuel cell bench test or accelerated life test, and does not consider the complexity and the variability of the actual working environment in the running process of a fuel cell automobile and the inaccuracy of sensor measurement, so that the prediction result of the service life of the fuel cell is inaccurate.
Disclosure of Invention
Based on this, it is necessary to provide a prediction method capable of accurately predicting the life of the fuel cell, aiming at the problem that the prediction result of the conventional fuel cell life estimation method is inaccurate.
The application provides a method for predicting the service life of a fuel cell, which comprises the following steps:
s10, acquiring the total time t of the accumulated start-stop process in the operation process of the fuel cell vehicle according to the operation working condition of the fuel cell vehicle1And accumulated operating time t of large load2Wherein the fuel cell vehicle is an extended range fuel cell-power cell hybrid vehicle equipped with a fuel cell;
s20, according to the total time t of the start-stop process1And the operating time t of the heavy load working condition2Obtaining a first voltage of the fuel cell irrespective of active area degradation
A first electrochemically active area S of the fuel cell1A first fuel cell internal resistance R of the fuel cell1The electrochemically active area degradation rate k of the fuel cellCAnd the internal resistance degradation rate k of the fuel cellRAnd constructing a voltage decline model of the fuel cell:
U＝[Ueq|0-I×R1-Aln(I)]-A×kC×t2-I×kR×t1
wherein I is the fuel cell current and A is the activation coefficient;
s30, providing a second electrochemically active area S of the fuel cell at time k2Internal resistance R of the second fuel cell of the fuel cell at the time k2；
S40, according to the second electrochemical active area S2And the internal resistance R of the second fuel cell2Determining the second electrochemical active area S2And said first electrochemically active area S1Is less than a predetermined value, and the internal resistance R of the second fuel cell2And the internal resistance R of the first fuel cell1Whether the internal resistance relative error is less than a preset value;
s50, if the judgment result is yes, predicting the voltage decline condition of the fuel cell according to the voltage decline model of the fuel cell;
s60, if the judgment result is negative, according to the second electrochemical active area S2And the internal resistance R of the second fuel cell2And correcting the voltage decline model of the fuel cell, and predicting the voltage decline condition of the fuel cell according to the corrected voltage decline model of the fuel cell.
In one embodiment, in the step S10, the total time t of the start-stop process1Is t1＝∫t|U＞aSaid operating time t of heavy load2Is t2＝∫t|I＞bWherein U > a represents a case where the output voltage of the fuel cell is large, and I > b represents a case where the current density of the fuel cell is large.
In one embodiment, the step S20 includes:
s210, constructing a voltage model of the fuel cell about k time when the fuel cell is applied to a large-current working area
U≈Erev+Aln(i1×S1)-I×R-Aln(I)＝Ueq-I×R-Aln(I)
Wherein E isrevTo reverse the open circuit voltage of the fuel cell, i1Is the exchange current density, U, of the fuel celleqR is the equivalent voltage of the fuel cell, R is the internal resistance of the fuel cell;
s220, according to the voltage model, carrying out comparison on the equivalent voltage UeqEstimating with the fuel cell internal resistance R to obtain the equivalent voltage UeqAnd the internal resistance R of the fuel cell;
s230, according to the equivalent voltage UeqBuilding up a voltage value for said equivalent voltage UeqThe first voltageThe electrochemically active area fade rate kCIs a relational expression of
S240, according to the equivalent voltage UeqThe first voltage
And the electrochemically active area degradation rate kCFor the first voltage
And the electrochemically active area degradation rate kCEstimating to obtain the first voltageAnd the electrochemically active area degradation rate kC；
S250, constructing the internal resistance R of the fuel cell and the internal resistance R of the first fuel cell according to the internal resistance R of the fuel cell1And the internal resistance decline rate kRIs a relational expression of
R＝R1+kR×t1
S260, according to the internal resistance R of the fuel cell and the internal resistance R of the first fuel cell1And the internal resistance decline rate kRFor the internal resistance R of the first fuel cell1And the internal resistance decline rate kREstimating to obtain the internal resistance R of the first fuel cell1And the internal resistance decline rate kR。
In one embodiment, in the step S220, the equivalent voltage U is processed by a least square method according to the voltage modeleqAnd the internal resistance R of the first fuel cell1Estimating to obtain the equivalent voltage UeqAnd the internal resistance R of the first fuel cell1。
In one embodiment, in the step S240, the first voltage is applied by a least square method
And the electrochemically active area degradation rate kCEstimating to obtain the first voltage
And the electrochemically active area degradation rate kC。
In one embodiment, in the step S260, the internal resistance R of the first fuel cell is determined by a least square method1And the internal resistance decline rate kREstimating to obtain the internal resistance R of the first fuel cell1And the internal resistance decline rate kR。
In one embodiment, the step S30 includes:
s310, providing a constant current charging device and an alternating current impedance measuring device;
s320, acquiring the second electrochemical active area S of the fuel cell at the moment k according to the constant current charging device2；
S330, acquiring the internal resistance R of the second fuel cell of the fuel cell at the moment k according to the alternating-current impedance measuring device2。
In one embodiment, in the step S310, the constant current charging device includes:
the test platform is connected with the fuel cell and is used for providing cooling and air supply functions for the fuel cell;
and the high-precision constant current source is connected with the fuel cell and is used for charging the fuel cell.
In one embodiment, the step S320 includes:
s321, introducing hydrogen and nitrogen into the fuel cell, and introducing cooling water with constant temperature to maintain the temperature of the galvanic pile;
s322, charging the fuel cell by adopting multiple different constant currents through the high-precision constant current source, and collecting the voltage of each single chip of the fuel cell under multiple different constant current charging conditions;
s323, stopping charging when the voltage of all the single sheets of the fuel cell exceeds 0.6V, and acquiring the voltage change rate dV/dt of each single sheet under different constant current charging conditions for many times;
s324, according to the voltage change rate of each single chip under the condition of multiple different constant current charging, obtaining the highest point (dV/dt) of the voltage change rate of each single chip under the condition of each constant current chargingHighest point of the designAnd constructing a highest point (dV/dt) with respect to the rate of change of voltageHighest point of the designAnd a charging current IGAEquation (2)
Wherein, CdlElectric double layer capacitor being a single chip iH2A hydrogen leakage current that is monolithic;
s325, according to the highest point (dV/dt) of the voltage change rateHighest point of the designAnd the charging current IGAObtaining the electric double layer capacitance C of each single chipdlAnd leakage of hydrogen current iH2And calculating the electrochemically active area S of each of the individual sheetsSheet
Wherein Q isH,AIs the amount of hydrogen adsorbed per unit area, WptIs the platinum loading per unit area.
S326, obtaining the electrochemical active area of all the single sheets of the fuel cell and averaging the electrochemical active area to be used as the second electrochemical active area S of the fuel cell at the moment k2。
In one embodiment, in the step S326, the electrochemical active areas of all the individual sheets of the fuel cell are sequentially obtained according to the step S324 and the step S325.
In one embodiment, in the step S20, the first voltage is used according to the first voltage
The internal resistance R of the first fuel cell1The electrochemically active area degradation rate kCThe internal resistance degradation rate kRThe first electrochemically active area S1Total time t of the start-stop process1And the operating time t under the large load condition2Constructing the voltage decay model of the fuel cell as
U＝[Ueq|0-I×R1-Aln(I)]-A×kC×t2-I×kR×t1
Wherein I is the fuel cell current and A is the activation coefficient.
In one embodiment, in the step S60, according to the second electrochemically active area S2And the internal resistance R of the second fuel cell2Updating the internal resistance R of the first fuel cell1And said first electrochemically active area S1And correcting the voltage degradation model of the fuel cell according to the step S20.
In one embodiment, a fuel cell life prediction apparatus comprises a processor for executing a program, wherein the program is executed to perform a fuel cell life prediction method as described in any one of the above.
In one embodiment, a computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements a fuel cell life prediction method as in any one of the above.
The application provides a fuel cell life prediction method, a prediction device and a computer readable storage medium. According to the fuel cell life prediction method, the operation condition data of the fuel cell are classified, the key parameters in the voltage decline model of the fuel cell are obtained by data fitting, the voltage decline condition of the fuel cell is estimated and predicted according to the voltage decline model of the fuel cell, and meanwhile, the accuracy of the life estimation of the fuel cell can be ensured by regularly feeding back the key parameters of the voltage decline model of the fuel cell, so that the accuracy of the estimation result is ensured.
Drawings
FIG. 1 is a schematic flow diagram of a fuel cell life prediction method provided herein;
fig. 2 is a schematic structural diagram of a constant current charging device provided in the present application;
FIG. 3 is a diagram illustrating a constant current charging method dV/dt according to the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below by way of embodiments and with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present application and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be considered as limiting the present application.
In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
Referring to fig. 1, the present application provides a method for predicting a life of a fuel cell, including:
s10, acquiring the total time t of the accumulated start-stop process in the operation process of the fuel cell vehicle according to the operation working condition of the fuel cell vehicle1And accumulated operating time t of large load2Wherein the fuel cell vehicle is an extended range fuel cell-power cell hybrid vehicle equipped with a fuel cell;
s20, according to the total time t of the start-stop process1And the operating time t of the heavy load working condition2Obtaining a first voltage of the fuel cell irrespective of active area degradation
A first electrochemically active area S of the fuel cell1A first fuel cell internal resistance R of the fuel cell1The electrochemically active area degradation rate k of the fuel cellCAnd the fuelInternal resistance degradation rate k of batteryRAnd constructing a voltage decline model of the fuel cell:
U＝[Ueq|0-I×R1-Aln(I)]-A×kC×t2-I×kR×t1(1)
wherein I is the fuel cell current and A is the activation coefficient;
s30, providing a second electrochemically active area S of the fuel cell at time k2Internal resistance R of the second fuel cell of the fuel cell at the time k2；
S40, according to the second electrochemical active area S2And the internal resistance R of the second fuel cell2Determining the second electrochemical active area S2And said first electrochemically active area S1Is less than a predetermined value, and the internal resistance R of the second fuel cell2And the internal resistance R of the first fuel cell1Whether the internal resistance relative error is less than a preset value;
s50, if the judgment result is yes, predicting the voltage decline condition of the fuel cell according to the voltage decline model of the fuel cell;
s60, if the judgment result is negative, according to the second electrochemical active area S2And the internal resistance R of the second fuel cell2And correcting the voltage decline model of the fuel cell, and predicting the voltage decline condition of the fuel cell according to the corrected voltage decline model of the fuel cell.
In the step S10, where the fuel cell vehicle is an extended range fuel cell-power cell hybrid vehicle with a fuel cell, the voltage degradation of the fuel cell vehicle can be analyzed according to the operation condition data of the fuel cell vehicle during actual operation. Aiming at the range-extended fuel cell-power cell hybrid electric vehicle, the actual operation data of the fuel cell vehicle is divided into two types according to working conditions: start-stop process and heavy-load operation condition. When the fuel cell of the fuel cell vehicle is operated at a low current densityWhen the device is used, the temperature of the device is easily influenced by the external environment, and the relative error of the current sensor in the small current area is large, so that the data running under the large current is selected as reliable data for prediction. The starting and stopping process corresponds to the condition that the output voltage of the fuel cell is larger, and the heavy-load working condition corresponds to the condition that the current density of the fuel cell is larger. By dividing the operation data of the fuel cell vehicle into two types according to the above conditions, the total time t of the accumulated start-stop process in the operation process of the fuel cell vehicle can be obtained1And accumulating the operating time t of the large load condition2。
In step S10, the total time t of the start-stop process1Is t1＝∫t|U＞aSaid operating time t of heavy load2Is t2＝∫t|I＞bWherein U > a represents a case where the output voltage of the fuel cell is large, and I > b represents a case where the current density of the fuel cell is large.
The step S20 includes:
s210, constructing a voltage model of the fuel cell when the fuel cell is applied to a high-current working area
U≈Erev+Aln(i1×S1)-I×R-Aln(I)＝Ueq-I×R-Aln(I) (2)
Wherein E isrevTo reverse the open circuit voltage of the fuel cell, i1Is the exchange current density, U, of the fuel celleqR is the equivalent voltage of the fuel cell, and R is the internal resistance of the fuel cell;
s220, according to the voltage model, carrying out comparison on the equivalent voltage UeqEstimating with the fuel cell internal resistance R to obtain the equivalent voltage UeqAnd the internal resistance R of the fuel cell;
s230, according to the equivalent voltage UeqBuilding up a voltage value for said equivalent voltage UeqThe first voltageThe electrochemically active area fade rate kCIs a relational expression of
S240, according to the equivalent voltage UeqThe first voltage
And the electrochemically active area degradation rate kCFor the first voltage
And the electrochemically active area degradation rate kCEstimating to obtain the first voltage
And the electrochemically active area degradation rate kC；
S250, constructing the internal resistance R of the fuel cell and the internal resistance R of the first fuel cell according to the internal resistance R of the fuel cell1And the internal resistance decline rate kRIs a relational expression of
R＝R1+kR×t1(4)
S260, according to the internal resistance R of the fuel cell and the internal resistance R of the first fuel cell1And the internal resistance decline rate kRFor the internal resistance R of the first fuel cell1And the internal resistance decline rate kREstimating to obtain the internal resistance R of the first fuel cell1And the internal resistance decline rate kR。
In the step S210, the total time t of the start-stop process is determined1And the operating time t of the heavy load working condition2And estimating key parameters in the voltage model. When the voltage model is applied to a high-current working area, concentration polarization and penetration current can be ignored, and the voltage model can be simplified into formula (2):
U≈Erev+Aln(i1×S1)-I×R-Aln(I)＝Ueq-I×R-Aln(I)
wherein E isrevTo reverse the open circuit voltage of the fuel cell, i1Is the exchange current density, U, of the fuel celleqIs the equivalent voltage of the fuel cell, R is the internal resistance of the fuel cell, A is the activation coefficient of the fuel cell, S1I is the electrochemically active area of the fuel cell and I is the current of the fuel cell.
In the step S220, according to the voltage model, the equivalent voltage U is measured by a least square methodeqEstimating with the fuel cell internal resistance R to obtain the equivalent voltage UeqAnd the internal resistance R of the fuel cell. The voltage model, i.e. the uncertain parameter U in equation (2)eqAnd R, which can be estimated using a least squares method, as follows:
wherein the content of the first and second substances,
in order for the vector to be solved for,
xnthe least squares solution of (c) is:
nopt＝argminεn(9)
εnto estimate the deviation, noptIs such that epsilonnMinimum sizeAnd (5) optimal solution.
In the steps S230 and S240, the voltage model is used to consider the effect of the performance degradation of the fuel cell, which is reflected in the reduction of the electrochemical active area and the increase of the internal resistance. Experimental data show that the electrochemically active area shows an exponential decreasing trend with the number of voltage cycles, so the decrease in electrochemically active area can be estimated using an exponential function:
in the step S240, the first voltage is processed by a least square method
And the electrochemically active area degradation rate kCEstimating to obtain the first voltage
And the electrochemically active area degradation rate kC. Wherein the first voltage
And the electrochemically active area degradation rate kCThe estimation can be performed using the least squares algorithm described above.
In the steps S250 and S260, the internal resistance R of the fuel cell in the equation (2) increases linearly with the operation time, and the increase of the internal resistance is mainly caused by the start-stop process, so the increase of the internal resistance can be estimated by the following formula:
R＝R1+kR×t1(11)
in the step S260, the internal resistance R of the first fuel cell is measured by the least square method1And the internal resistance decline rate kREstimating to obtain the internal resistance R of the first fuel cell1And the internal resistance decline rate kR. Wherein the first fuel cell has an internal resistance R1And the internal resistance decline rate kRAlso, the same applies toThe estimation can be performed using the least squares algorithm described above.
Through the above-mentioned series of formula analyses, the voltage degradation model of the fuel cell can be represented by formula (1), i.e., U ═ Ueq|0-I×R1-Aln(I)]-A×kC×t2-I×kR×t1。
In one embodiment, in the step S40, the predetermined value is 5%, that is, the second electrochemically active area S is2And the internal resistance R of the second fuel cell2Respectively with the first electrochemical active area S1And the internal resistance R of the first fuel cell1Comparing the two to judge the second electrochemical active area S2And said first electrochemically active area S1Whether the relative error of the chemically active area of (a) is less than 5%, and the internal resistance R of the second fuel cell2And the internal resistance R of the first fuel cell1Whether the internal resistance relative error is less than 5%.
In the step S50, when the second electrochemical active area S is smaller than the first electrochemical active area S2And said first electrochemically active area S1Whether the relative error of the chemically active area of (a) is less than 5%, and the internal resistance R of the second fuel cell2And the internal resistance R of the first fuel cell1If the relative error of the internal resistance is less than 5%, predicting the voltage degradation condition of the fuel cell according to the voltage degradation model of the fuel cell by the formula (1).
In the step S60, if the determination result is negative, the second electrochemical active area S is determined2And the internal resistance R of the second fuel cell2Replacing said first electrochemically active area S1And the internal resistance R of the first fuel cell1The voltage degradation model of the fuel cell is corrected, so that the corrected voltage degradation model of the fuel cell, that is, the corrected voltage degradation model of the fuel cell can be obtained
U＝[Ueq|0-I×R2-Aln(I)]-A×kC×t2-I×kR×t1(12)
Equation (12) predicts the voltage decay of the fuel cell based on the corrected voltage decay model of the fuel cell.
According to the fuel cell life prediction method, the operation condition data of the fuel cell are classified, the key parameters in the voltage decline model of the fuel cell are obtained by data fitting, the voltage decline condition of the fuel cell is estimated and predicted according to the voltage decline model of the fuel cell, and meanwhile, the accuracy of the life estimation of the fuel cell can be ensured by regularly feeding back the key parameters of the voltage decline model of the fuel cell, so that the accuracy of the estimation result is ensured.
In step S30, the second electrochemically active area S of the fuel cell at time k is acquired2And obtaining the internal resistance R of the second fuel cell of the fuel cell at the moment k2The time k can be corrected at intervals, and the time can be determined according to actual conditions.
In one embodiment, the step S30 includes:
s310, providing a constant current charging device and an alternating current impedance measuring device;
s320, acquiring the second electrochemical active area S of the fuel cell at the moment k according to the constant current charging device2；
S330, acquiring the internal resistance R of the second fuel cell of the fuel cell at the moment k according to the alternating-current impedance measuring device2。
Wherein the constant current charging device calculates the second electrochemical active area S of the fuel cell at the time k by adopting a constant current charging method2The AC impedance measuring device calculates the internal resistance R of the second fuel cell at the time k by using an AC impedance measuring method2. And according to said second electrochemically active area S2And the internal resistance R of the second fuel cell2For S in formulas (9) and (10)1And R1And (6) correcting.
Referring to fig. 2, in one embodiment, in the step S310, the constant current charging device includes a test bench, a fuel cell, and a high precision constant current source. The fuel cell is connected with the test bench, and the test bench is used for providing cooling and air supply functions for the fuel cell. The high-precision constant current source is connected with the fuel cell and used for charging the fuel cell.
The anode and the cathode of the fuel cell are connected with the high-precision constant current source, and the high-precision constant current source can charge the fuel cell. The fuel cell is also connected to an accessory system or test stand. The test station or accessory system can provide cooling and gas supply functions to the fuel cell, wherein the cooling system can control the overall temperature of the fuel cell and the gas supply system can provide gases of different humidity to the cathode and anode of the fuel cell. When it is desired to obtain the active area of the cathode side of each single piece of the fuel cell, the anode of the high-precision constant current source is connected to the anode of the fuel cell, and the cathode of the high-precision constant current source is connected to the cathode of the fuel cell. And nitrogen is introduced into the cathode side of the fuel cell, and hydrogen is introduced into the anode side of the fuel cell. When the active area of each single anode is desired to be obtained, the anode of the high-precision constant current source is connected with the cathode of the fuel cell, the cathode of the high-precision constant current source is connected with the anode of the fuel cell, nitrogen is introduced into the anode of the fuel cell, and hydrogen is introduced into the cathode of the fuel cell.
In one embodiment, the step S320 includes:
s321, introducing hydrogen and nitrogen into the fuel cell, and introducing cooling water with constant temperature to maintain the temperature of the galvanic pile;
s322, charging the fuel cell by adopting multiple different constant currents through the high-precision constant current source, and collecting the voltage of each single chip of the fuel cell under multiple different constant current charging conditions;
s323, stopping charging when the voltage of all the single sheets of the fuel cell exceeds 0.6V, and acquiring the voltage change rate dV/dt of each single sheet under different constant current charging conditions for many times;
s324, obtaining each single chip according to the voltage change rate of each single chip under the condition of multiple different constant current chargingPeak of each single-chip voltage change rate (dV/dt) under one-time constant current charging conditionHighest point of the designAnd constructing a highest point (dV/dt) with respect to the rate of change of voltageHighest point of the designAnd a charging current IGAEquation (2)
Wherein, CdlElectric double layer capacitor being a single chip iH2A hydrogen leakage current that is monolithic;
s325, according to the highest point (dV/dt) of the voltage change rateHighest point of the designAnd the charging current IGAObtaining the electric double layer capacitance C of each single chipdlAnd leakage of hydrogen current iH2And calculating the electrochemically active area S of each of the individual sheetsSheet
Wherein Q isH,AIs the amount of hydrogen adsorbed per unit area, WptIs the platinum loading per unit area.
S326, obtaining the electrochemical active area of all the single sheets of the fuel cell and averaging the electrochemical active area to be used as the second electrochemical active area S of the fuel cell at the moment k2。
In the step S321, the fuel cell is supplied with hydrogen and nitrogen, and is supplied with cooling water at a constant temperature to maintain the stack temperature. In order to ensure the testing precision, the humidity of the passing hydrogen and nitrogen is enough to ensure that all reaction areas under normal working conditions can be fully soaked. At the same time, the aeration time needs to be kept long enough before the test so that the internal state is stable.
In step S323, the high-precision constant current source is used to select different constant currents to charge the fuel cell stack. And in the charging process, acquiring the voltage change of all the single chips of the fuel cell by a high-precision rapid collecting system. And stopping charging when the voltage of all the single sheets of the fuel cell exceeds 0.6V. In addition, the high-precision constant current source also needs to have a step change function, so that the current can be instantly increased from 0A to the target current.
Referring to fig. 3, the voltage change rate dV/dt of the same single chip under different constant current charging conditions is obtained. Acquiring the voltage of the same single chip of the fuel cell under different constant-current charging conditions for multiple times, and processing the voltage data by dV/dt to obtain the voltage change rate dV/dt of the same single chip under each constant-current charging condition, wherein the highest point of the dV/dt generally appears at a determined voltage position. According to the data processing method, the voltage change rate dV/dt of each single chip under the condition of multiple different constant current charging of the fuel cell can be obtained.
According to the voltage change rate dV/dt of the same single chip under the conditions of multiple times of different constant current charging, the highest point (dV/dt) of the voltage change rate of the same single chip under the conditions of multiple times of different constant current charging can be obtainedHighest point of the design. Thus, the highest point (dV/dt) with respect to the voltage change rate is constructed therefromHighest point of the designAnd a charging current IGAAnd simultaneously solving the equations (2) and (13) to obtain the monolithic electric double layer capacitor CdlAnd leakage of hydrogen current iH2And further obtaining a monolithic electrochemically active area S according to the formula (14)Sheet。
Based on the voltage change rate of each single chip under the condition of multiple different constant current charging, the highest point (dV/dt) of the voltage change rate of each single chip under the condition of each constant current charging can be obtainedHighest point of the designIn turn, the highest point (dV/dt) with respect to the rate of change of voltage is constructedHighest point of the designAnd a charging current IGAAnd simultaneously solving the equations according to the formula (13), thereby obtaining the electric double layer capacitance C of each single chipdlAnd leakage of hydrogen current iH2。
In the step S325, the electric double layer capacitance C is formed on a per-chip basisdlAnd the hydrogen leakage current iH2The electrochemically active area S of each of the individual sheets can be calculated according to the formula (14)Sheet. Wherein equation (14) is the integral of the voltage over the interval 0 to the maximum voltage.
Thus, according to the above method, the highest point (dV/dt) with respect to the rate of change of voltage of each individual piece of the fuel cell can be constructedHighest point of the designAnd a charging current IGAAnd simultaneously solving the equations according to the formula (13), thereby obtaining the electric double layer capacitance C of each single chipdlAnd leakage of hydrogen current iH2. Thus, the electric double layer capacitance C is based on each single sheetdlAnd the hydrogen leakage current iH2The electrochemically active area S of each of the individual sheets can be calculated according to the formula (14)Sheet。
In step S326, the electrochemical active areas of all the individual pieces of the fuel cell may be obtained in sequence according to step S324 and step S325, and the average value of the electrochemical active areas of all the individual pieces is used as the second electrochemical active area S of the fuel cell at time k2。
In one embodiment, the overpotential due to the anode is negligibly low, when it is desired to obtain the cathode electrochemically active area of the fuel cell as the second electrochemically active area S of the fuel cell at time k2。
In one embodiment, in the step S60, according to the second electrochemically active area S2And the internal resistance R of the second fuel cell2Updating the internal resistance R of the first fuel cell1And said first electrochemically active area S1And correcting the voltage degradation model of the fuel cell according to the step S20.
According to the second electrochemical active area S2And the internal resistance R of the second fuel cell2Replacing said first electrochemically active area S1And the internal resistance R of the first fuel cell1Correcting the voltage degradation model of the fuel cell so that the corrected voltage degradation model of the fuel cell, that is, formula (12), can be obtained
U＝[Ueq|0-I×R2-Aln(I)]-A×kC×t2-I×kR×t1
And predicting the voltage decline condition of the fuel cell according to the corrected voltage decline model of the fuel cell.
In one embodiment, the method for predicting the service life of the fuel cell can be applied to an extended-range fuel cell passenger car, and actual operation data of the fuel cell car is divided into two types according to working conditions. When the fuel cell operates under low current density, the temperature of the fuel cell is easily influenced by the external environment, and the relative error of the current sensor in the low current area is large, so that the data of the operation under the large current is selected as reliable data for prediction. Aiming at the extended range fuel cell bus, the actual operation data of the fuel cell vehicle is divided into two types according to the working conditions: start-stop process and heavy-load operation condition. The starting and stopping process corresponds to the condition that the output voltage of the fuel cell is larger, and the heavy-load working condition corresponds to the condition that the current density of the fuel cell is larger. By dividing the operation data of the fuel cell automobile into two types according to the conditions, the total time t of the accumulated start-stop process in the operation process of the fuel cell can be obtained1And accumulating the operating time t of the large load condition2。
According to the fuel cell life prediction method, the operation condition data of the fuel cell are classified, the key parameters in the voltage decline model of the fuel cell are obtained by data fitting, the voltage decline condition of the fuel cell is estimated and predicted according to the voltage decline model of the fuel cell, and meanwhile, the accuracy of the life estimation of the fuel cell can be ensured by regularly feeding back the key parameters of the voltage decline model of the fuel cell, so that the accuracy of the estimation result is ensured.
In one embodiment, a fuel cell life prediction apparatus comprises a processor for executing a program, wherein the program is executed to perform a fuel cell life prediction method as described in any one of the above.
In one embodiment, a computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements a fuel cell life prediction method as in any one of the above.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (14)
1. A method of predicting a life of a fuel cell, comprising:
s10, acquiring the total time t of the accumulated start-stop process in the operation process of the fuel cell vehicle according to the operation working condition of the fuel cell vehicle1And accumulated operating time t of large load2Wherein the fuel cell vehicle is an extended range fuel cell-power cell hybrid vehicle equipped with a fuel cell;
s20, according to the total time t of the start-stop process1And the operating time t of the heavy load working condition2Obtaining a first voltage of the fuel cell irrespective of active area degradationA first electrochemically active area S of the fuel cell1A first fuel cell internal resistance R of the fuel cell1The electrochemically active area degradation rate k of the fuel cellCAnd the internal resistance degradation rate k of the fuel cellRAnd constructing a voltage decline model of the fuel cell:
U＝[Ueq|0-I×R1-Aln(I)]-A×kC×t2-I×kR×t1
wherein I is the fuel cell current and A is the activation coefficient;
s30, providing a second electrochemically active area S of the fuel cell at time k2Internal resistance R of the second fuel cell of the fuel cell at the time k2；
S40, according to the second electrochemical active area S2And the internal resistance R of the second fuel cell2Determining the second electrochemical active area S2And said first electrochemically active area S1Is less than a predetermined value, and the internal resistance R of the second fuel cell2And the internal resistance R of the first fuel cell1Whether the internal resistance relative error is less than a preset value;
s50, if the judgment result is yes, predicting the voltage decline condition of the fuel cell according to the voltage decline model of the fuel cell;
s60, if the judgment result is negative, according to the second electrochemical active area S2And the internal resistance R of the second fuel cell2And correcting the voltage decline model of the fuel cell, and predicting the voltage decline condition of the fuel cell according to the corrected voltage decline model of the fuel cell.
2. The method of predicting the life span of a fuel cell according to claim 1, wherein the total time t of the start-stop process in step S101Is t1＝∫t|U＞aSaid operating time t of heavy load2Is t2＝∫t|I＞bWherein U > a represents a case where the output voltage of the fuel cell is large, and I > b represents a case where the current density of the fuel cell is large.
3. The fuel cell life prediction method according to claim 1, characterized in that the step S20 includes:
s210, constructing a voltage model of the fuel cell when the fuel cell is applied to a high-current working area
U≈Erev+Aln(i1×S1)-I×R-Aln(I)＝Ueq-I×R-Aln(I)
Wherein E isrevTo reverse the open circuit voltage of the fuel cell, i1Is the exchange current density, U, of the fuel celleqR is the equivalent voltage of the fuel cell, and R is the internal resistance of the fuel cell;
s220, according to the voltage model, carrying out comparison on the equivalent voltage UeqEstimating with the fuel cell internal resistance R to obtain the equivalent voltage UeqAnd the internal resistance R of the fuel cell;
s230, according to the equivalent voltage UeqBuilding up a voltage value for said equivalent voltage UeqThe first voltage Ueq|0The electrochemically active area degradation rate kCIs a relational expression of
S240, according to the equivalent voltage UeqThe first voltage
And the electrochemically active area degradation rate kCFor the first voltageAnd the electrochemically active area degradation rate kCEstimating to obtain the first voltage
And the electrochemically active area degradation rate kC；
S250, constructing the internal resistance R of the fuel cell and the internal resistance R of the first fuel cell according to the internal resistance R of the fuel cell1And the internal resistance decline rate kRIs a relational expression of
R＝R1+kR×t1
S260, according to the internal resistance R of the fuel cell and the internal resistance R of the first fuel cell1And the internal resistance decline rate kRFor the internal resistance R of the first fuel cell1And the internal resistance decline rate kREstimating to obtain the internal resistance R of the first fuel cell1And the internal resistance decline rate kR。
4. The method of predicting the lifetime of a fuel cell according to claim 3, wherein in said step S220, said equivalent voltage U is calculated by a least square method based on said voltage modeleqAnd the internal resistance R of the first fuel cell1Estimating to obtain the equivalent voltage UeqAnd the internal resistance R of the first fuel cell1。
5. The fuel cell life prediction method according to claim 3, wherein in the step S240, the first voltage is subjected to least square processing
And the electrochemically active area degradation rate kCEstimating to obtain the first voltage
And the electrochemically active area degradation rate kC。
6. The fuel cell life prediction method according to claim 3, wherein in the step S260, the first fuel cell internal resistance R is subjected to least square processing1And the internal resistance decline rate kREstimating to obtain the internal resistance R of the first fuel cell1And the internal resistance decline rate kR。
7. The fuel cell life prediction method according to claim 1, characterized in that the step S30 includes:
s310, providing a constant current charging device and an alternating current impedance measuring device;
s320, acquiring the second electrochemical active area S of the fuel cell at the moment k according to the constant current charging device2；
S330, acquiring the internal resistance R of the second fuel cell of the fuel cell at the moment k according to the alternating-current impedance measuring device2。
8. The fuel cell life prediction method according to claim 7, wherein in the step S310, the constant-current charging device includes:
the test platform is connected with the fuel cell and is used for providing cooling and air supply functions for the fuel cell;
and the high-precision constant current source is connected with the fuel cell and is used for charging the fuel cell.
9. The fuel cell life prediction method according to claim 8, wherein the step S320 includes:
s321, introducing hydrogen and nitrogen into the fuel cell, and introducing cooling water with constant temperature to maintain the temperature of the galvanic pile;
s322, charging the fuel cell by adopting multiple different constant currents through the high-precision constant current source, and collecting the voltage of each single chip of the fuel cell under multiple different constant current charging conditions;
s323, stopping charging when the voltage of all the single sheets of the fuel cell exceeds 0.6V, and acquiring the voltage change rate dV/dt of each single sheet under different constant current charging conditions for many times;
s324, according to the voltage change rate of each single chip under the condition of multiple different constant current charging, obtaining the highest point (dV/dt) of the voltage change rate of each single chip under the condition of each constant current chargingHighest point of the designAnd constructing a highest point (dV/dt) with respect to the rate of change of voltageHighest point of the designAnd a charging current IGAEquation (2)Formula (II)
Wherein, CdlElectric double layer capacitor being a single chip iH2A hydrogen leakage current that is monolithic;
s325, according to the highest point (dV/dt) of the voltage change rateHighest point of the designAnd the charging current IGAObtaining the electric double layer capacitance C of each single chipdlAnd leakage of hydrogen current iH2And calculating the electrochemically active area S of each of the individual sheetsSheet
Wherein Q isH,AIs the amount of hydrogen adsorbed per unit area, WptIs the platinum loading per unit area and,
the monolithic voltage corresponding to the maximum value of dV/dt;
s326, obtaining the electrochemical active area of all the single sheets of the fuel cell and averaging the electrochemical active area to be used as the second electrochemical active area S of the fuel cell at the moment k2。
10. The method of predicting the lifetime of a fuel cell according to claim 8, wherein in said step S326, the electrochemically active areas of all the individual pieces of said fuel cell are sequentially obtained in accordance with said step S324 and said step S325.
11. The fuel cell life prediction method according to claim 1, characterized in that in the step S20, based on the first voltage
The internal resistance R of the first fuel cell1The electrochemical activity ofArea fading rate kCThe internal resistance degradation rate kRThe first electrochemically active area S1Total time t of the start-stop process1And the operating time t under the large load condition2Constructing the voltage decay model of the fuel cell as
U＝[Ueq|0-I×R1-Aln(I)]-A×kC×t2-I×kR×t1
Wherein I is the fuel cell current and A is the activation coefficient.
12. The method for predicting the lifetime of a fuel cell according to claim 1, wherein in said step S60, said second electrochemically active area S is used as a basis2And the internal resistance R of the second fuel cell2Updating the internal resistance R of the first fuel cell1And said first electrochemically active area S1And correcting the voltage decay model of the fuel cell.
13. A fuel cell life prediction device comprising a processor for executing a program, wherein the program is executed to perform the fuel cell life prediction method according to any one of claims 1 to 12.
14. A computer-readable storage medium, having stored thereon a computer program, characterized in that the computer program, when being processed and executed, implements a fuel cell life prediction method according to any one of claims 1 to 12.
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