CN114325434A - Fuel cell electrochemical impedance spectrum detection device and detection method - Google Patents

Abstract

The present invention provides a fuel cell electrochemical impedance spectroscopy detection device and a detection method, wherein the detection device includes a plurality of parallel boost circuits, a current detection module, and a voltage detection module for detecting the voltage at both ends of the stack. The boost circuits are all connected to the stack, each of the boost circuits can generate an excitation source, the number of the current detection modules is the same as the number of the boost circuits, and all the current detection modules are respectively used to detect all the boost circuits and the power supply. The magnitude of the current in the stack phase connection segment. The fuel cell electrochemical impedance spectroscopy detection device and the detection method have higher detection accuracy and higher detection efficiency for the fuel cell electrochemical impedance spectroscopy.

Description

Fuel cell electrochemical impedance spectroscopy detection device and detection method

technical field

The invention relates to the technical field of fuel cells, in particular to a fuel cell electrochemical impedance spectroscopy detection device and a detection method.

Background technique

As a new green technology, hydrogen fuel cell is a research hotspot in the field of new energy. Now as an important technical direction of new energy vehicles, proton exchange membrane fuel cells.

Because the internal resistance comprehensively reflects the internal humidity, temperature and health status of the hydrogen fuel cell. Real-time monitoring of the internal resistance of fuel cells is of great significance to ensure the safety and efficient operation of hydrogen fuel cells. However, hydrogen fuel cells are nonlinear and time-varying systems, and it is generally difficult to accurately measure the impedance parameters of the battery. And the internal impedance of the battery is in the order of milliohms, which increases the difficulty of measuring the battery's accuracy. At present, the mainstream internal resistance detection method at home and abroad is the AC impedance spectroscopy method, which uses a small amplitude AC voltage and current to disturb the fuel cell, conducts the internal resistance test of the fuel cell, and obtains the AC impedance data. For the AC impedance method, the sine wave is used for the disturbance, which has the advantage of being easy to generate and analyze; the disadvantage is that most of the disturbance is realized by using an external excitation source, and the frequency needs to be swept from low frequency to high frequency during the test process to test the internal impedance of each frequency end. The impedance spectrum is obtained, the execution time is long, the efficiency is low, and the impedance state cannot be reflected in real time. At present, there is also a relatively innovative solution that uses triangular wave disturbance, and sends 10HZ, 100HZ, 1000HZ frequencies, and obtains the impedance spectrum by detecting the voltage and current and performing FFT analysis to obtain the internal impedance of different frequencies; The amplitude attenuation is severe, resulting in a relatively large error at the high frequency end; and it is also necessary to send out several triangular waves of different frequencies, which still has the problem of a long wave sending time. That is, the method of generating triangular wave disturbance has the problems of low detection accuracy and low efficiency.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a fuel cell electrochemical impedance spectroscopy detection device with higher detection efficiency.

In order to achieve the above purpose, the present invention provides a fuel cell electrochemical impedance spectroscopy detection device, including a plurality of parallel boost circuits, a current detection module, and a voltage detection module for detecting the voltage at both ends of the stack. The circuits are all connected to the stack, each of the boost circuits can generate an excitation source, the number of the current detection modules is the same as the number of the boost circuits, and all the current detection modules are respectively used to detect all the boost circuits and the stack. The magnitude of the current in the connected segments.

Further, the fuel cell electrochemical impedance spectroscopy detection device further includes a DFFT module, and all the current detection modules and voltage detection modules are connected to the DFFT module.

Further, the fuel cell electrochemical impedance spectroscopy detection device further includes a memory, the current detection module and the voltage detection module are both connected to the memory, and the DFFT module is connected to the memory.

Further, the fuel cell electrochemical impedance spectroscopy detection device further includes a current A/D conversion module, and the current detection module is connected to the memory through the current A/D conversion module.

Further, the fuel cell electrochemical impedance spectroscopy detection device further includes a voltage A/D conversion module, and the voltage detection module is connected to the memory through the voltage A/D conversion module.

Further, the fuel cell electrochemical impedance spectroscopy detection device further includes an arithmetic control unit and a pulse width modulation unit connected with the arithmetic control unit, all the current detection modules are connected with the arithmetic control unit, and the pulse width The modulation unit is connected with all the boost circuits.

Further, all the current detection modules are connected with the current A/D conversion module, and the current A/D conversion module is connected with the arithmetic control unit.

As described above, the fuel cell electrochemical impedance spectroscopy detection device involved in the present invention has the following beneficial effects:

The working principle of the fuel cell electrochemical impedance spectrum detection device is as follows: all the boost circuits send waves of different frequency bands to the stack at the same time, and all the current detection modules detect the current values of all the boost circuits connected to the stack respectively, so as to obtain different The current value of the frequency band; the voltage detection module obtains the voltage value formed by the superposition of the waves emitted by all the boost circuits by detecting the voltage at both ends of the stack, so as to obtain the voltage value of different frequency bands, according to the current value of different frequency bands and different frequency bands. The impedance value of different frequency bands can be calculated from the voltage value of , and the impedance spectrum can be generated according to the obtained impedance values of different frequency bands. The detection device uses the boost circuit to generate the excitation source, and uses multiple boost circuits to generate waves of different frequency bands. This method has a short wave generation time, which can greatly improve the efficiency of the stack impedance detection, and can achieve a true sense of Real-time detection of stack impedance, and can more accurately obtain the impedance spectrum of the fuel cell, which is convenient for real-time and accurate detection of the health status of the fuel cell, thereby greatly improving the safety factor of the use of the fuel cell, especially in the hydrogen fuel cell new energy vehicle. Can greatly improve the safety factor.

Another technical problem to be solved by the present invention is to provide a detection method with higher detection efficiency and higher precision.

In order to achieve the above purpose, the present invention provides a detection method using the fuel cell electrochemical impedance spectroscopy detection device, comprising the following steps:

All Boost circuits send square waves of different frequency bands to the stack at the same time, and all current detection modules detect the current values of all Boost circuits connected to the stack respectively, and then perform DFFT analysis on the obtained current values to calculate the current in different frequency bands. value; the voltage detection module obtains the voltage value formed by the superposition of square waves emitted by all Boost circuits by detecting the voltage at both ends of the stack, and then performs DFFT analysis on the obtained voltage value to calculate the voltage value in different frequency bands. The current value and the voltage value of different frequency bands are used to calculate the impedance value of different frequency bands.

Further, at least one Boost circuit sends 10HZ square wave, at least one Boost circuit sends 50HZ square wave, at least one Boost circuit sends 100HZ square wave, at least one Boost circuit sends 500HZ square wave, at least one Boost circuit sends 1000HZ square wave, and at least one Boost circuit sends 1000HZ square wave. The Boost circuit sends out a 5000HZ square wave.

Further, after filtering out the direct current in the current value obtained by the current detection module, the current value is then subjected to DFFT analysis and calculation; after filtering out the direct current in the voltage value obtained by the voltage detection module, the voltage value Perform DFFT analysis calculations.

As mentioned above, the detection method involved in the present invention has the following beneficial effects:

In this detection method, the boost circuit is used as the excitation source, which saves the wave generation time, thereby greatly improving the detection efficiency; at the same time, the square wave is used for detection, which avoids the high frequency amplitude attenuation of the triangular wave, which leads to poor sampling accuracy, and further improves the detection efficiency. The accuracy of this detection method is guaranteed to be higher.

Description of drawings

FIG. 1 is a schematic structural diagram of a fuel cell electrochemical impedance spectroscopy detection device in an embodiment of the present invention.

Component label description

1 Boost circuit

2 Current detection module

3 Voltage detection module

4 stacks

5 DFFT module

6 memory

7 Current A/D conversion module

8 Voltage A/D conversion module

9 Operation Control Unit

10 Pulse width modulation unit

11 Analysis and judgment module

12 VCU modules

13 FCS module

Detailed ways

The embodiments of the present invention are described below by specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

It should be noted that the structures, proportions, sizes, etc. shown in the accompanying drawings of this specification are only used to cooperate with the contents disclosed in the specification for the understanding and reading of those who are familiar with the technology, and are not used to limit the conditions for the implementation of the present invention. , therefore does not have technical substantive significance, any structural modification, proportional relationship change or size adjustment, without affecting the effect that the present invention can produce and the purpose that can be achieved, should still fall within the scope of the present invention. within the scope of the technical content. At the same time, terms such as "up", "down", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the present invention. The scope of implementation, the change or adjustment of the relative relationship, and the technical content without substantial change, shall also be regarded as the scope of the present invention.

As shown in FIG. 1 , this embodiment provides a fuel cell electrochemical impedance spectroscopy detection device, including a plurality of parallel boost circuits 1 , a current detection module 2 , and a voltage detection module for detecting the voltage across the stack 4 . 3. All Boost circuits 1 are connected to stack 4. Each Boost circuit 1 can generate an excitation source. The number of current detection modules 2 is the same as that of Boost circuits 1. All current detection modules 2 are used to detect all Boost circuits respectively. The magnitude of the current in the connection section between circuit 1 and stack 4. The working principle of the fuel cell electrochemical impedance spectroscopy detection device is as follows: all the boost circuits 1 send waves of different frequency bands to the stack 4 at the same time, and all the current detection modules 2 respectively detect the currents of all the boost circuits 1 and the stack 4 connected to each other. The voltage detection module 3 obtains the voltage value formed by the superposition of all the waves emitted by the Boost circuit 1 by detecting the voltage at both ends of the stack 4, so as to obtain the voltage value of different frequency bands, according to different frequencies The current value of the segment and the voltage value of different frequency segments are used to calculate the impedance value of different frequency segments, and the impedance spectrum can be generated according to the obtained impedance values of different frequency segments. In the detection device, the boost circuit 1 is used to generate the excitation source, and multiple boost circuits 1 are used to generate waves of different frequency bands. This method has a shorter wave generation time, which can greatly improve the efficiency of the impedance detection of the stack 4, and can realize the real In the sense of real-time detection of the impedance of the stack 4, and the impedance spectrum of the fuel cell can be obtained more accurately, it is convenient to detect the health status of the fuel cell in real time and accurately, thereby greatly improving the safety factor of the use of the fuel cell, especially in the hydrogen fuel cell. New energy vehicles can greatly improve the safety factor.

In this embodiment, the fuel cell electrochemical impedance spectroscopy detection device further includes a DFFT module 5, a memory 6, a current A/D conversion module 7 and a voltage A/D conversion module 8. All the current detection modules 2 are converted with current A/D The module 7 is connected, the voltage detection module 3 is connected with the voltage A/D conversion module 8, the current A/D conversion module 7 and the voltage A/D conversion module 8 are connected with the memory 6, and the memory 6 is in turn connected with the DFFT module 5. connect. All current detection modules 2 feed back the current value of the corresponding Boost circuit 1 and the connection section of the stack 4 to the current A/D conversion module 7, and the current A/D conversion module 7 converts the analog signal of the current value into a digital signal and sends it Store it in the memory 6, the voltage detection module 3 feeds back the detected voltage value to the voltage A/D conversion module 8, and the voltage A/D conversion module 8 converts the analog signal of the voltage value into a digital signal and sends it to the memory 6 for processing. Store, the DFFT module 5 calculates the current values in the memory 6 through DFFT analysis to obtain current values in different frequency segments, and the DFFT module 5 calculates the voltage values in the memory 6 through DFFT analysis to obtain the voltage values in different frequency segments, and then through the impedance The calculation method calculates the impedance value of different frequency bands, and draws the generated impedance spectrum.

As shown in FIG. 1, the fuel cell electrochemical impedance spectroscopy detection device in this embodiment further includes an arithmetic control unit 9 and a pulse width modulation unit 10 connected to the arithmetic control unit 9, a current A/D conversion module 7 and an arithmetic control unit 10. The unit 9 is connected, and the pulse width modulation unit 10 is connected with all the boost circuits 1 . The current A/D conversion module 7 sends the current value of each Boost circuit 1 to the connection section of the stack 4 to the arithmetic control unit 9, and the arithmetic control unit 9 according to the detected current situation, including the band width, etc., and according to the set situation The adjustment of each Boost circuit 1 is realized by controlling the pulse width modulation unit 10 to ensure that the state of the waves emitted by each Boost circuit 1 meets the set requirements.

Meanwhile, this embodiment provides a detection method using the fuel cell electrochemical impedance spectroscopy detection device, comprising the following steps:

All Boost circuits 1 send square waves of different frequency bands to stack 4 at the same time, all current detection modules 2 detect the current values of all Boost circuits 1 and stack 4 connected sections respectively, and then perform DFFT analysis and calculation on the obtained current values. The current values of different frequency segments; the voltage detection module 3 obtains the voltage values formed by the superposition of square waves emitted by all Boost circuits 1 by detecting the voltage across the stack 4, and then performs DFFT analysis on the obtained voltage values to obtain the voltage values of different frequency segments. Voltage value, according to the current value of different frequency bands and the voltage value of different frequency bands to calculate the impedance value of different frequency bands.

In this detection method, the boost circuit 1 is used as the excitation source, which saves the wave generation time and greatly improves the detection efficiency. This ensures that the detection method has a higher accuracy.

The detection method in this embodiment specifically filters out the direct current in the current value obtained by the current detection module 2, and then performs DFFT analysis and calculation on the current value; and performs DFFT analysis and calculation on the current value; After filtering, the voltage value is subjected to DFFT analysis and calculation.

The detection device and detection method in this embodiment relate to the detection of the internal resistance of the hydrogen fuel cell. The Boost circuit 1 is used as the excitation source to realize the on-line electrochemical impedance spectroscopy detection of the hydrogen fuel cell, and the multi-channel Boost circuit 1 is used. At the same time, the square wave is sent out, which is beneficial to improve the detection accuracy. In the whole process, there are multiple excitation sources integrated in multiple Boost circuits 1 that are interleaved and connected in parallel. Through n interleaved parallel Boost circuits 1, n excitation sources can be generated, and only by controlling the Boost circuit 1 to control the fuel cell current to generate a DC current and a square wave that does not affect the stability of the control slightly to form a current. After the fuel cell is stabilized, the voltage and current of the fuel cell are sampled for DFFT analysis, and the internal impedance of the fuel cell at each frequency is obtained. Chemical impedance spectroscopy. The whole detection device and method adopts the excitation source design, which overcomes the shortcomings of the prior art, such as long frequency sweep time of sine wave, serious attenuation of high frequency amplitude of triangular wave, poor sampling accuracy, and long time to give different frequency triangular waves in time division. .

In addition, from the FFT analysis of the square wave and the triangular wave, it can be seen that the high frequency content of the square wave is n/2 times that of the triangular wave.

FFT of a square wave:

FFT of a triangular wave:

For example, in this embodiment, 6 channels of Boost circuit can be used to emit 1 wave, the first channel of Boost circuit can emit 10HZ square wave, the second channel of Boost circuit can emit 1 50HZ square wave, the third channel of Boost circuit can emit 100HZ square wave, and the third channel of Boost circuit can emit 100HZ square wave. The four-way Boost circuit sends one 500HZ square wave, the fifth-way Boost circuit sends one 1000HZ square wave, and the sixth-way Boost circuit sends one 5000HZ square wave. DC-DC is a 6-channel interleaved parallel Boost circuit 1, which emits waves at the same time; the current is detected by different current detection channels, and the DC is filtered out through circuit processing, and then A/D conversion is sent to DSP to obtain different frequency bands through DFFT analysis and calculation current value. The voltage value generated by the superposition of 6 square waves is obtained by voltage sampling, and the DC quantity is filtered out through the circuit processing, and then the A/D conversion is sent to the DSP to analyze and calculate the different frequency voltage values through DFFT. The impedance value of different frequency bands is calculated by the impedance calculation method, and the impedance spectrum is generated by drawing.

In addition, as shown in FIG. 1 , the fuel cell electrochemical impedance spectroscopy detection device in this embodiment further includes an analysis and judgment module 11 connected with the DFFT module 5 , the analysis and judgment module 11 is connected with the VCU module 12 , and the VCU module 12 is connected with the DFFT module 5 . The FCS module 13 is connected. In this embodiment, the arithmetic control unit 9 , the pulse width modulation unit 10 , the current detection module 2 , the voltage detection module 3 , the A/D conversion module, the memory 6 , the DFFT module 5 and the analysis and judgment module 11 constitute the main control unit of the detection device .

To sum up, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (10)

1. The device for detecting the electrochemical impedance spectrum of the fuel cell is characterized by comprising a plurality of parallel-connected Boost circuits (1), current detection modules (2) and voltage detection modules (3) for detecting the voltage at two ends of an electric pile (4), wherein all the Boost circuits (1) are connected with the electric pile (4), each Boost circuit (1) can generate an excitation source, the number of the current detection modules (2) is the same as that of the Boost circuits (1), and all the current detection modules (2) are respectively used for detecting the current of the sections, connected with the electric pile (4), of all the Boost circuits (1).

2. The fuel cell electrochemical impedance spectroscopy detection apparatus according to claim 1, further comprising a DFFT module (5), wherein all of the current detection module (2) and the voltage detection module (3) are connected to the DFFT module (5).

3. The fuel cell electrochemical impedance spectroscopy detection apparatus according to claim 2, further comprising a memory (6), wherein the current detection module (2) and the voltage detection module (3) are both connected to the memory (6), and the DFFT module (5) is connected to the memory (6).

4. The fuel cell electrochemical impedance spectroscopy detection apparatus according to claim 3, further comprising a current A/D conversion module (7), wherein the current detection module (2) is connected to the memory (6) through the current A/D conversion module (7).

5. The fuel cell electrochemical impedance spectroscopy detection apparatus according to claim 3, further comprising a voltage A/D conversion module (8), wherein the voltage detection module (3) is connected to the memory (6) through the voltage A/D conversion module (8).

6. The fuel cell electrochemical impedance spectroscopy detection device according to claim 1, further comprising an arithmetic control unit (9) and a pulse width modulation unit (10) connected with the arithmetic control unit (9), wherein all the current detection modules (2) are connected with the arithmetic control unit (9), and the pulse width modulation unit (10) is connected with all the Boost circuits (1).

7. The fuel cell electrochemical impedance spectroscopy detection apparatus according to claim 6, wherein all the current detection modules (2) are connected to a current A/D conversion module (7), and the current A/D conversion module (7) is connected to an arithmetic control unit (9).

8. A method of testing using the fuel cell electrochemical impedance spectroscopy apparatus of claim 1, comprising the steps of:

all the Boost circuits (1) send square waves of different frequency sections to the galvanic pile (4) at the same time, all the current detection modules (2) respectively detect the current values of the sections where all the Boost circuits (1) are connected with the galvanic pile (4), and then DFFT analysis calculation is carried out on the obtained current values to obtain the current values of different frequency sections; the voltage detection module (3) detects the voltages at the two ends of the galvanic pile (4) to obtain voltage values formed by superposition of square waves emitted by all the Boost circuits (1), then performs DFFT analysis and calculation on the obtained voltage values to obtain voltage values of different frequency sections, and calculates impedance values of different frequency sections according to current values of different frequency sections and voltage values of different frequency sections.

9. The detection method according to claim 8, wherein at least one of the Boost circuits (1) sends 10HZ square waves, at least one of the Boost circuits (1) sends 50HZ square waves, at least one of the Boost circuits (1) sends 100HZ square waves, at least one of the Boost circuits (1) sends 500HZ square waves, at least one of the Boost circuits (1) sends 1000HZ square waves, and at least one of the Boost circuits (1) sends 5000HZ square waves.

10. The detection method according to claim 8, characterized in that after the direct current amount in the current value obtained by the current detection module (2) is filtered, the current value is subjected to DFFT analysis calculation; and after the direct current quantity in the voltage value obtained by the voltage detection module (3) is filtered, the voltage value is subjected to DFFT analysis and calculation.

Images