Fuel cell impedance evaluation method, system, computer and vehicle

Abstract

The present invention relates to the field of fuel cell technology, and in particular to a fuel cell impedance evaluation method, system, computer and vehicle. The present invention calculates the change of a disturbance signal applied to a fuel cell stack and the frequency spectrum of a target disturbance signal not applied to the fuel cell stack, calculates the signal-to-noise ratio of the two at specified frequency points, and compares the two to evaluate the fuel cell stack impedance value. By adopting the signal-to-noise comparison method, the influence of fuel cell polarization on numerical accuracy can be ignored, and the measurement frequency range of high-frequency impedance and the accuracy of low-frequency impedance measurement can be improved. The voltage divided by current is reduced, and the deviation of the two parameter data is simplified, thereby improving the accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell impedance evaluation method, system, computer and vehicle. Background Art

[0002] As emissions from traditional vehicles increasingly impact the environment, new energy vehicles have become a crucial solution to addressing vehicle exhaust emissions. The development of fuel cell vehicles has also garnered significant public attention, with fuel cell engines increasingly being incorporated into various manufacturers and models, becoming a popular choice for everyday commuting.

[0003] However, the development of fuel cell technology also faces the following problems: during the operation of the fuel cell, the humidity of the internal operating environment determines the life and reliability of the fuel cell itself, but the existing technology cannot install sensors inside the fuel cell stack under commercial operating conditions to detect its operating status. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fuel cell impedance evaluation method, system, computer and vehicle that improve the reliability and stability of the fuel cell by determining the dry and wet conditions inside the fuel cell stack through collecting and calculating the spectrum distribution of the square wave disturbance signal based on the existing AC impedance detection equipment.

[0005] In order to solve the above technical problems, the first technical solution adopted by the present invention is:

[0006] A fuel cell impedance evaluation method comprising:

[0007] Apply a disturbance signal S1 of a first specified frequency to both the positive and negative electrodes of the fuel cell;

[0008] Collect the change signal S2 of the fuel cell collection end;

[0009] In the process of applying the disturbance signal S1 to the positive and negative electrodes of the fuel cell, a second specified frequency is used and a signal S of a specified length is collected;

[0010] Perform frequency domain signal conversion on S1 and S2 respectively;

[0011] Determine the position n1 of the frequency point corresponding to the disturbance signal;

[0012] Calculate the signal-to-noise ratio SNR1 of S1 at frequency point n1 and the signal-to-noise ratio SNR2 of S2 at frequency point n1 respectively;

[0013] The dry and wet conditions of the fuel cell stack are evaluated by the ratio parameters of SNR1 and SNR2.

[0014] Preferably, the first specified frequency is f d ; The second specified frequency is f s ; The specified length is N;

[0015] The disturbance signal f is determined d The calculation formula for the corresponding frequency point position n1 is:

[0016]

[0017] C is a constant.

[0018] Preferably, the disturbance signal S1 includes current and voltage, and the change signal S2 includes current and voltage.

[0019] Preferably, the fuel cell stack impedance value variation distribution is set, and the actual value of the impedance is measured by actual measuring equipment to obtain a control value, and the control value has a one-to-one correspondence with the proportional parameter value.

[0020] In order to solve the above technical problems, the second technical solution adopted by the present invention is:

[0021] A fuel cell impedance evaluation system, comprising

[0022] A disturbance signal generator applies a disturbance signal S1 of a first specified frequency to the positive and negative electrodes of the fuel cell;

[0023] A collector collects a change signal S2 at a fuel cell collection end; uses a second specified frequency and collects a signal S of a specified length during the process of applying a disturbance signal S1 to both sides of the fuel cell;

[0024] The processor converts the domain frequency signals of S1 and S2 respectively; determines the position n1 of the frequency point number corresponding to the disturbance signal; solves the signal-to-noise ratio SNR1 of S1 at the frequency point n1, and the signal-to-noise ratio SNR2 of S2 at the frequency point n1; and evaluates the dry and wet conditions of the fuel cell stack through the ratio parameters of SNR1 and SNR2.

[0025] Preferably, the first specified frequency is f d ; The second specified frequency is f s ; The specified length is N;

[0026] The disturbance signal f is determined d The calculation formula for the corresponding frequency point position n1 is:

[0027]

[0028] C is a constant.

[0029] Preferably, the collector is a voltage collector;

[0030] Or the collector includes a voltage collector and a current collector.

[0031] Preferably, the disturbance signal generator comprises a switch and a load resistor connected in series, and the switch is electrically controlled or manually controlled.

[0032] In order to solve the above technical problems, the third technical solution adopted by the present invention is:

[0033] A computer includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned fuel cell impedance evaluation method is implemented.

[0034] In order to solve the above technical problems, the fourth technical solution adopted by the present invention is:

[0035] A vehicle includes the above-mentioned fuel cell impedance evaluation system.

[0036] The beneficial effects of the present invention are as follows: calculating the change of the disturbance signal applied to the fuel cell stack and the spectrum of the target disturbance signal not applied to the fuel cell stack, calculating the signal-to-noise ratio of the two at the specified frequency points, and comparing the two to evaluate the impedance value of the fuel cell stack; because the signal-to-noise comparison method is adopted, the influence of the fuel cell polarization on the numerical accuracy can be ignored, the measurement frequency range of the high-frequency impedance and the accuracy of the low-frequency impedance measurement can be improved; reducing the voltage divided by the current, the deviation of the two parameter data, simplifying the design and improving the accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is an equivalent circuit model diagram of a battery impedance evaluation system in Example 1 (the dashed box is the fuel cell stack equivalent circuit);

[0038] Figure 2 The voltage and current waveforms of S1 and S2 in Example 2 are shown;

[0039] Figure 3 The waveforms of the domain frequency signals of S1 and S2 in Example 2 are converted respectively;

[0040] Figure 4 is R of S1 and S2 in Example 2 z Determine the disturbance signal f d Refer to the corresponding frequency point position n1;

[0041] Explanation of the reference numbers: 1. disturbance signal generator; 2. resistor; 3. capacitor; 4. voltage collector; 5. current collector. DETAILED DESCRIPTION

[0042] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the embodiments and accompanying drawings.

[0043] Example 1

[0044] Reference Figure 1 , a fuel cell impedance evaluation system, comprising

[0045] The disturbance signal generator 1 applies the first specified frequency f on both sides of the positive and negative electrodes of the fuel cell d The disturbance signal S1;

[0046] The collector collects the change signal S2 of the fuel cell collection end; in the process of applying the disturbance signal S1 on both sides of the positive and negative electrodes of the fuel cell, the second specified frequency f is used. s And collect the signal S of specified length N;

[0047] The processor converts the domain frequency signals of S1 and S2 respectively; determines the position n1 of the frequency point number corresponding to the disturbance signal; solves the signal-to-noise ratio SNR1 of S1 at the frequency point n1, and the signal-to-noise ratio SNR2 of S2 at the frequency point n1; and evaluates the dry and wet conditions of the fuel cell stack through the ratio parameters of SNR1 and SNR2.

[0048] The disturbance signal f is determined d The calculation formula for the corresponding frequency point position n1 is:

[0049]

[0050] C is a constant.

[0051] The collector includes a voltage collector 4 and a current collector 5 .

[0052] The disturbance signal generator includes a switch and a load resistor connected in series, and the switch is electrically controlled or manually controlled.

[0053] Example 2

[0054] A fuel cell impedance evaluation system, which is similar to the first embodiment and will not be repeated here, wherein the collector is a voltage collector 4. Since the fuel cell stack has the characteristics of resistance 2 and capacitance 3 at the same time, the data collected by the voltage collector 4 can be directly converted into current information.

[0055] Example 3

[0056] Reference Figure 2-4 , a fuel cell impedance evaluation method, comprising

[0057] Apply the first specified frequency f to both the positive and negative electrodes of the fuel cell d The disturbance signal S1, such as Figure 2Left part: the disturbance signal S1 includes current and voltage;

[0058] Collect the change signal S2 at the fuel cell acquisition end; because the fuel cell stack has both resistance and capacitance properties, the signal S2 will be collected at the voltage acquisition end. Figure 2 Right part: the change signal S2 includes current and voltage;

[0059] The second specified frequency f is used in the process of applying the disturbance signal S1 to the positive and negative electrodes of the fuel cell. s And collect the signal S of specified length N;

[0060] Convert the domain frequency signals of S1 and S2 respectively, and refer to the converted images Figure 3 ;

[0061] Determine the position n1 of the frequency point corresponding to the disturbance signal;

[0062] R z Determine the disturbance signal f d The calculation formula for the corresponding frequency point position n1 is:

[0063]

[0064] C is a constant.

[0065] Calculate the signal-to-noise ratio SNR1 of S1 at frequency point n1 and the signal-to-noise ratio SNR2 of S2 at frequency point n1 respectively;

[0066] The dry and wet conditions of the fuel cell stack are evaluated by the ratio parameters of SNR1 and SNR2, that is,

[0067]

[0068] The impedance value distribution of the fuel cell stack is assumed to change continuously from dry state to wet state. The actual value of the impedance Rn = (1, 2, 3...n) is measured using actual measuring equipment. The values ​​correspond one to one. As shown in the following table:

[0069]

[0070] Example 4

[0071] A computer comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the fuel cell impedance evaluation method as described in any one of the third embodiments is implemented.

[0072] Example 5

[0073] A vehicle, characterized by comprising the fuel cell impedance evaluation system described in any one of the first embodiment or the second embodiment.

[0074] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A fuel cell impedance evaluation method, characterized in that: The method comprises applying a disturbance signal S1 of a first specified frequency to both the positive and negative electrodes of the fuel cell; Collect the change signal S2 of the fuel cell collection end; In the process of applying the disturbance signal S1 to the positive and negative electrodes of the fuel cell, a second specified frequency is used and a signal S of a specified length is collected; Perform frequency domain signal conversion on S1 and S2 respectively; Determine the position n1 of the frequency point corresponding to the disturbance signal; Calculate the signal-to-noise ratio SNR1 of S1 at frequency point n1 and the signal-to-noise ratio SNR2 of S2 at frequency point n1 respectively; The dry and wet conditions of the fuel cell stack are evaluated by the ratio parameters of SNR1 and SNR2; Wherein, the first specified frequency is f d ; The second specified frequency is f s ; The specified length is N; The first designated frequency f d The calculation formula for the corresponding frequency point position n1 is: C is a constant; Wherein, the disturbance signal S1 includes current and voltage, and the change signal S2 includes current and voltage; The change distribution of the impedance value of the fuel cell stack is set, and the actual value of the impedance is measured by actual measuring equipment to obtain a control value, and the control value corresponds to the proportional parameter value one by one.

2. A fuel cell impedance evaluation system, characterized in that: The fuel cell impedance evaluation system is based on the fuel cell impedance evaluation method of claim 1, comprising a disturbance signal generator for applying a disturbance signal S1 of a first specified frequency to both the positive and negative electrodes of the fuel cell; Collector, collecting the change signal S2 of the fuel cell collection end; In the process of applying the disturbance signal S1 to the positive and negative electrodes of the fuel cell, a second specified frequency is used and a signal S of a specified length is collected; The processor converts the domain frequency signals of S1 and S2 respectively; Determine the position n1 of the frequency point corresponding to the disturbance signal; Calculate the signal-to-noise ratio SNR1 of S1 at frequency point n1 and the signal-to-noise ratio SNR2 of S2 at frequency point n1 respectively; The dry and wet conditions of the fuel cell stack are evaluated by the ratio parameters of SNR1 and SNR2; Wherein, the first specified frequency is f d ; The second specified frequency is f s ; The specified length is N; The first designated frequency f d The calculation formula for the corresponding frequency point position n1 is: C is a constant.

3. The fuel cell impedance evaluation system according to claim 2, wherein: The collector is a voltage collector; Or the collector includes a voltage collector and a current collector.

4. The fuel cell impedance evaluation system according to claim 3, wherein: The disturbance signal generator includes a switch and a load resistor connected in series, and the switch is electrically controlled or manually controlled.

5. A computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the fuel cell impedance evaluation method according to claim 1 is implemented.

6. A vehicle, characterized in that: A fuel cell impedance evaluation system comprising the fuel cell impedance evaluation system according to any one of claims 2 to 4.

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