Method and device for calculating hydrogen utilization of a fuel cell

Abstract

The application discloses a kind of fuel cell hydrogen utilization rate calculation method and equipment, belong to fuel cell technical field.The method includes: hydrogen utilization rate=electric pile consumption hydrogen mass flow rate / into electric pile hydrogen mass flow rate;Into electric pile hydrogen mass flow rate is based on aperture section area, flow coefficient C v , pressure, temperature, gas constant and hydrogen adiabatic index calculation;Flow coefficient C v Real-time iteration updates, and the trigger condition is: tail exhaust valve is not opened and electric pile pressure remains unchanged;With long-period hydrogen utilization rate is corrected to short-period hydrogen utilization rate;The long-period hydrogen utilization rate is the average value of hydrogen utilization rate within a certain time of hydrogen cylinder;The steps of correction include: dividing calibration interval;Solving a polynomial correction coefficient;Correct short-period data and smooth processing between different intervals.The application can calculate hydrogen utilization rate in real time with high precision, low cost, strong adaptability, and can close-loop control tail exhaust valve.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a method and device for calculating the hydrogen utilization rate of a fuel cell. Background Technology

[0002] Currently, hydrogen utilization rates are not calculated in vehicles equipped with fuel cell systems. Calculating hydrogen utilization rates requires obtaining hydrogen flow rate and fuel cell stack current. Due to the high cost of hydrogen flow sensors, they are only installed during experimental testing and calibration phases to obtain hydrogen utilization rates for calibrating the hydrogen exhaust valve. The exhaust valve control is open-loop control; closed-loop control is not used for hydrogen utilization rate.

[0003] This method of calculating hydrogen utilization using a hydrogen flow sensor is costly and not suitable for large-scale application. It also cannot obtain real-time hydrogen utilization data, hindering precise control of the hydrogen tail-end valve and easily leading to low hydrogen utilization rates.

[0004] Therefore, a new method for calculating the hydrogen utilization rate of fuel cells is needed to address the shortcomings of existing technologies. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in the aforementioned related technologies.

[0006] Therefore, the purpose of this invention is to provide a method and device for calculating the hydrogen utilization rate of a fuel cell, which does not require a hydrogen flow sensor, can calculate the hydrogen utilization rate in real time with high accuracy, and is low-cost, highly adaptable, and can control the tailpipe valve in a closed loop.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: This invention provides a method for calculating the hydrogen utilization rate of a fuel cell, the method including short-cycle hydrogen utilization rate calculation, the calculation formula being: , In the formula, Hydrogen utilization rate; : Hydrogen mass flow rate consumed by the fuel cell stack; The mass flow rate of hydrogen entering the fuel cell stack via a proportional valve or hydrogen injector.

[0008] Furthermore, the method for calculating the hydrogen utilization rate of a fuel cell according to the present invention may also have the following additional technical features: In some of these embodiments, the hydrogen mass flow rate consumed by the fuel cell stack is calculated based on the number of stack units, the relative molecular mass of hydrogen, the Faraday constant, and the stack current.

[0009] In some embodiments, the hydrogen enters the fuel cell stack via a proportional valve. The hydrogen mass flow rate is based on the proportional valve orifice cross-sectional area and flow coefficient. C v The inlet pressure, inlet temperature, gas constant, and hydrogen adiabatic index were calculated. The hydrogen enters the fuel cell stack through a hydrogen injector. The hydrogen mass flow rate is based on the orifice cross-sectional area of ​​the hydrogen injection valve, the opening time, the closing time, and the flow coefficient. C v The parameters are calculated based on inlet pressure, inlet temperature, gas constant, and hydrogen adiabatic index.

[0010] In some implementations, the stack current, inlet pressure, inlet temperature, orifice cross-sectional area, and hydrogen injection on / off time when the anode pressure fluctuation is less than a certain threshold are extracted for the purpose of calculating the flow rate into the stack.

[0011] In some of these implementations, the flow coefficient C v Real-time iterative updates; the trigger condition for iterative updates is: the tail valve is not open and the fuel cell stack pressure remains unchanged.

[0012] In some of these implementations, the flow coefficient C v The steps for real-time iterative updates include: S11. Initialization: Establish initialization using historical data. C v Model; S12. C v Value and C v Model parameter updates: real-time correction C v Eliminate errors caused by valve aging and operating condition drift; S13. Calculation of hydrogen flow rate into the reactor: based on current real-time parameters and C v Latest Model Predictions C v Value, based on C v The value is used to calculate the hydrogen flow rate into the reactor.

[0013] In some embodiments, the method further includes correcting the short-cycle hydrogen utilization rate with the long-cycle hydrogen utilization rate; The long-cycle hydrogen utilization rate is the average hydrogen utilization rate of the hydrogen cylinder over a certain period of time.

[0014] In some of these embodiments, the step of correcting the short-cycle hydrogen utilization rate with the long-cycle hydrogen utilization rate includes: S21. Divide the calibration interval: Calculate the average hydrogen utilization rate of the hydrogen cylinder within a specific time period, and use it as the long-cycle hydrogen utilization rate; S22. Calculate the average short-cycle hydrogen utilization rate within each calibration interval; S23. Solve for the first-order polynomial correction coefficients: The constraint for this solution process is that the mean of the short-period interval equals the mean of the long-period interval; the polynomial correction coefficients include the proportional correction coefficients and the offset correction coefficients; S24. Correct short-period data and smooth between different intervals: Correct short-period instantaneous values ​​with correction coefficients and perform linear transition in overlapping areas of adjacent intervals.

[0015] In some of these embodiments, the formula for calculating the proportional correction factor is: ; The formula for calculating the offset correction coefficient is as follows: ; The formula for correction within the interval is: ; The formula for handling interval connections is: , ; In the formula: For the first k The average hydrogen utilization rate of short cycles within a long cycle; For the first k The average hydrogen utilization rate over a long period; As a weighting factor; N The number of short cycles within a long period.

[0016] This invention also provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for calculating the hydrogen utilization rate of a fuel cell as described in any of the preceding embodiments.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: In this embodiment of the invention, the method for calculating the hydrogen utilization rate of a fuel cell can obtain the hydrogen utilization rate in real time, support the closed-loop control of the hydrogen tail valve, solve the problem of low utilization rate caused by traditional open-loop control, and improve the economy of the hydrogen fuel cell system. In this embodiment of the invention, the method for calculating the hydrogen utilization rate of a fuel cell provides a method for iteratively updating the valve in real time under constant anode pressure. C vThis value significantly improves the accuracy of hydrogen infeed flow rate calculation, thereby enhancing the overall accuracy of hydrogen utilization rate calculation. In this embodiment of the invention, the method for calculating the hydrogen utilization rate of fuel cells integrates the advantages of short-cycle real-time calculation and long-cycle high-precision calculation, taking into account both the real-time performance and accuracy of the calculation, and outputting stable and reliable hydrogen utilization rate data. In this embodiment of the invention, the method for calculating the hydrogen utilization rate of fuel cells does not require the use of expensive hydrogen flow sensors. It can calculate the hydrogen utilization rate by relying on the existing sensors of the vehicle, which greatly reduces hardware costs and is suitable for large-scale vehicle application.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Figure 1 This is a block diagram illustrating the calculation method for hydrogen utilization rate in a fuel cell, as disclosed in one embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and specific examples and application scenarios.

[0022] Please see Figure 1 As shown, in some embodiments of the present invention, a method for calculating the hydrogen utilization rate of a fuel cell is provided. The formula for calculating the hydrogen utilization rate is: Formula 1 Formula 2 In the formula, Hydrogen utilization rate; Hydrogen mass flow rate consumed by the fuel cell stack, g / min; The flow rate of hydrogen entering the fuel cell stack through the proportional valve or hydrogen injector is in g / min. Hydrogen gas is discharged through the tailpipe valve at a flow rate of g / min.

[0023] Because the hydrogen gas discharged when the tailpipe valve is opened contains impurities such as liquid water, gaseous water, and nitrogen, Formula 2 is difficult to calculate accurately.

[0024] The hydrogen mass flow rate consumed by the fuel cell stack for power generation can be calculated using formula 3: Formula 3 In the formula: N Number of individual solar cells in the fuel cell stack; : Relative molecular mass of hydrogen, g / mol; F Faraday constant, 96485 C / mol; i : Pile current, A.

[0025] In practical applications, the hydrogen pressure in the reactor core is more than twice the hydrogen inlet pressure, therefore the hydrogen proportioning valve is always in a blocked state. The formula for calculating the hydrogen mass flow rate from the proportioning valve into the reactor core is: Formula 4 In the formula: The orifice cross-sectional area of ​​the hydrogen proportional valve or injection valve, in m 2 ; For hydrogen proportional valves or injection valves; This refers to the inlet pressure of the hydrogen proportional valve or injection valve. This refers to the inlet temperature of the hydrogen proportional valve or injection valve. It is the gas constant; This represents the adiabatic index of hydrogen.

[0026] The formula for calculating the hydrogen mass flow rate from the hydrogen injector into the fuel cell stack is: Formula 5 In the formula: The hydrogen injection valve opening time (after delay correction), in seconds; , is the closing time of the hydrogen injection valve, in seconds.

[0027] A proportional valve is a special case of a hydrogen injector. T off =0, A e When the proportional valve opening is defined as the actual cross-sectional area / maximum cross-sectional area, Formula 5 is the same as Formula 4.

[0028] When the tail valve is not open and the fuel cell stack pressure remains constant (by finding when the anode pressure fluctuation is less than a certain threshold, extracting the corresponding fuel cell stack current, anode pressure, temperature, proportional valve opening degree, and hydrogen injection opening and closing time), the mass flow rate of hydrogen consumed by the fuel cell stack is equal to the mass flow rate of hydrogen flowing into the fuel cell stack through the hydrogen proportional valve or hydrogen injector (Equation 6). Under this condition, the flow rate through the hydrogen proportional valve or hydrogen injector can be measured by the fuel cell stack current (Equation 3). By observing the valve opening degree and valve flow rate, a mapping relationship between valve opening degree and flow coefficient is established.

[0029] Formula 6 Step 1: Initialization When the anode pressure of the fuel cell stack is constant, collect historical data from the hydrogen proportional valve or injection valve: ( , , , ), ( , , , ),..., ( , , , ) In the formula: i,j This refers to the proportional valve opening. i This indicates different valve opening degrees, that is, the first... i Specimen opening degree; j This represents different flow rates, pressures, and temperature conditions, which is the first... j Medium environmental conditions; n This represents the total number of environmental states.

[0030] Inferring details from historical data: ; In the formula: K This is the operating condition coefficient.

[0031] Initial fitting: Fitting a quadratic polynomial model using the least squares method The polynomial coefficients of the initial parameters of the proportional valve are obtained. The coefficients of the quadratic polynomial are the fitting coefficients of the quadratic form. The fitting accuracy of the quadratic form can meet the requirements, and the amount of calculation is not large. It is the optimal choice of this invention. Initialize the parameters of Weighted Recursive Least Squares (WRLS): covariance matrix ( I (As an identity matrix, with high initial uncertainty), weighting factors lValues ​​range from 0 to 1, and the actual values ​​that can be obtained are... .

[0032] Step 2: Calculation C v and model parameter updates Measured input when the anode pressure of the fuel cell stack is constant: hydrogen proportional valve or injection valve (Standardized to 0~1), inlet pressure Inlet temperature .

[0033] Calculate the operating condition coefficient: .

[0034] Reverse push C v value: .

[0035] Remove outliers: .

[0036] WRLS parameter update: The input vector is: ; k 1 indicates the first type of opening; The Kalman gain is: ; Model parameter iteration: ; Covariance update: ; Output the updated model parameters: .

[0037] i For the parameters of Weighted Recursive Least Squares (WRLS), i 0 is the initial value, here i k It is the iteration value.

[0038] Step 3: Flow Calculation Current operating parameter input: opening degree of hydrogen proportional valve or injection valve Inlet pressure Inlet temperature .

[0039] Calculate the operating condition coefficient: .

[0040] Model prediction C v : .

[0041] Flow calculation: .

[0042] The hydrogen utilization rate can be calculated within one cycle of the tailpipe valve's operation. The calculation formula is as follows: ; In the formula: Hydrogen utilization rate is calculated using a hydrogen proportioning valve or injection valve.

[0043] The formula for calculating the mass of hydrogen consumed by a hydrogen storage cylinder is: ; In the formula: From T 0 to T The mass of hydrogen gas flowing out of the hydrogen cylinder at moment 1; V Let m be the volume of the hydrogen cylinder. 3 ; M The molar mass of hydrogen is expressed in g / mol. Z It is the hydrogen compressibility factor; R is the gas constant.

[0044] for T Hydrogen cylinder pressure at time 0, Pa; for T Temperature of the hydrogen tank at time 0, in K; for T Hydrogen cylinder pressure at moment 1, Pa; for T Temperature of the hydrogen flask at moment 1, in K.

[0045] The hydrogen utilization rate can be calculated based on the mass of hydrogen flowing from the hydrogen cylinder into the fuel cell stack over a period of time: ; In the formula: This represents the hydrogen utilization rate calculated using a hydrogen cylinder.

[0046] Hydrogen cylinder calculations offer high accuracy in hydrogen utilization, but require long measurement cycles. Calculations using proportional valves or hydrogen injectors offer lower accuracy but shorter measurement cycles. The core logic is as follows: using a long-cycle, high-precision average as the "baseline true value," within each long cycle, a first-order polynomial (linear correction) is used to align the "interval average" of short-cycle data with the long-cycle measurement value, while simultaneously correcting for linear drift / offset errors in the short-cycle data. The final output is a short-cycle instantaneous signal with improved accuracy.

[0047] Step 1: Divide the calibration interval Short-cycle hydrogen utilization rate calculation: ; Long-term hydrogen utilization rate calculation: .

[0048] Step 2: Calculate the short-cycle hydrogen utilization rate within each calibration interval. The average value.

[0049] .

[0050] Step 3: Solve for the correction coefficients of the first-order polynomial.

[0051] The average hydrogen utilization rate is constrained to be equal for both long and short cycles: .

[0052] Let the initial value be: , .

[0053] Calculation of proportional correction factor: .

[0054] Offset correction factor calculation: .

[0055] k It refers to the usage time of long-period time intervals. i It is a short-period sampling time interval.

[0056] Step 4: Correct short-period signals and smooth the interval connections.

[0057] Intra-range correction: ; ( (This is the corrected value) Interval transition processing: Abrupt changes in the correction coefficients of adjacent intervals may cause jumps in the corrected signal. This needs to be addressed in the overlapping interval regions (such as the last interval). N A linear transition is performed on (number of data points). ; .

[0058] Any part of this invention not described in detail can be referred to in the prior art or in the art known to those skilled in the art. This embodiment does not limit such part and will not describe it in detail here.

[0059] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A method for calculating the hydrogen utilization rate of a fuel cell, characterized in that, The method includes short-cycle hydrogen utilization rate calculation, and the calculation formula is as follows: ， In the formula, Hydrogen utilization rate; : Hydrogen mass flow rate consumed by the fuel cell stack; The mass flow rate of hydrogen entering the fuel cell stack via a proportional valve or hydrogen injector.

2. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 1, characterized in that, The hydrogen mass flow rate consumed by the fuel cell stack is calculated based on the number of individual stack plates, the relative molecular mass of hydrogen, the Faraday constant, and the stack current.

3. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 1, characterized in that, The hydrogen enters the fuel cell stack through a proportional valve. The hydrogen mass flow rate is based on the proportional valve orifice cross-sectional area and flow coefficient. C v The inlet pressure, inlet temperature, gas constant, and hydrogen adiabatic index were calculated. The hydrogen enters the fuel cell stack through a hydrogen injector. The hydrogen mass flow rate is based on the orifice cross-sectional area of ​​the hydrogen injection valve, the opening time, the closing time, and the flow coefficient. C v The parameters are calculated based on inlet pressure, inlet temperature, gas constant, and hydrogen adiabatic index.

4. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 3, characterized in that, The stack current, inlet pressure, inlet temperature, orifice cross-sectional area, and hydrogen injection on / off time are extracted when the anode pressure fluctuation is less than a certain threshold, and used to calculate the flow rate entering the stack.

5. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 3, characterized in that, For flow coefficient C v Real-time iterative updates; the trigger condition for iterative updates is: the tail valve is not open and the fuel cell stack pressure remains unchanged.

6. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 5, characterized in that, For flow coefficient C v The steps for real-time iterative updates include: S11. Initialization: Establish initialization using historical data. C v Model; S12. C v Value and C v Model parameter updates: real-time correction C v Eliminate errors caused by valve aging and operating condition drift; S13. Calculation of hydrogen flow rate into the reactor: based on current real-time parameters and C v Latest Model Predictions C v Value, based on C v The value is used to calculate the hydrogen flow rate into the reactor.

7. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 1, characterized in that, The method also includes correcting the short-cycle hydrogen utilization rate using the long-cycle hydrogen utilization rate; The long-cycle hydrogen utilization rate is the average hydrogen utilization rate of the hydrogen cylinder over a certain period of time.

8. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 7, characterized in that, The steps for correcting short-cycle hydrogen utilization rate using long-cycle hydrogen utilization rate include: S21. Divide the calibration interval: Calculate the average hydrogen utilization rate of the hydrogen cylinder within a specific time period, and use it as the long-cycle hydrogen utilization rate; S22. Calculate the average short-cycle hydrogen utilization rate within each calibration interval; S23. Solve for the first-order polynomial correction coefficients: The constraint for this solution process is that the mean of the short-period interval equals the mean of the long-period interval; the polynomial correction coefficients include the proportional correction coefficients and the offset correction coefficients; S24. Correct short-period data and smooth between different intervals: Correct short-period instantaneous values ​​with correction coefficients and perform linear transition in overlapping areas of adjacent intervals.

9. The method for calculating the hydrogen utilization rate of a fuel cell according to claim 8, characterized in that, The formula for calculating the proportional correction factor is: ; The formula for calculating the offset correction coefficient is as follows: ; The formula for correction within the interval is: ; The formula for handling interval connections is: , ; In the formula: For the first k The average hydrogen utilization rate of short cycles within a long cycle; For the first k The average hydrogen utilization rate over a long period; As a weighting factor; N This represents the number of short cycles within a long period.

10. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the method for calculating the hydrogen utilization rate of a fuel cell according to any one of claims 1-9.

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