Electrochemical impedance measuring circuit and method, chip and electronic equipment

Abstract

The embodiment of the invention provides an electrochemical impedance measurement circuit and method, a chip and electronic equipment, and the circuit comprises an excitation module which is used for outputting an excitation signal, and the excitation signal is used for exciting an impedance module to output a response signal; the measuring module is used for determining the electrochemical impedance of the impedance module at the corresponding frequency according to the response signal of the corresponding frequency; wherein the preset frequency range comprises a plurality of sub-frequency ranges, the frequency of the excitation signal in each sub-frequency range is determined according to the corresponding set frequency step length, and the set frequency step lengths corresponding to at least two sub-frequency ranges are not equal. According to the method and the device, the set frequency step length of a certain sub-frequency range can be set according to actual requirements, so that more or less measurement frequency points are selected in the sub-frequency range, and the flexibility of electrochemical impedance spectroscopy measurement is improved.

Description

Technical Field

[0001] This application relates to the field of detection technology, and particularly to an electrochemical impedance measurement circuit, method, chip and electronic device. Background Art

[0002] Electrochemical impedance spectroscopy is widely used in the research of positive and negative electrode materials of lithium-ion batteries, the study of lithium-ion insertion and extraction kinetic parameters, solid electrolytes, interfacial reactions, etc., and is a powerful tool for analyzing the performance of lithium-ion batteries. Currently, the electrochemical impedance spectroscopy measurement method mainly generates an alternating current excitation signal at each measurement frequency point, uses the alternating current excitation signal to excite the battery and makes the battery output a response signal. After measuring the response signals corresponding to each measurement frequency point, the impedance of the battery at each measurement frequency point can be calculated, and the electrochemical impedance spectroscopy of the battery can be obtained by combining the impedances of the battery at each measurement frequency point.

[0003] In related technologies, the electrochemical impedance spectroscopy measurement method usually selects measurement frequency points in a fixed frequency step manner. For example, assuming that the measurement frequency range is 0.01 Hz to 10 kHz and the fixed frequency step is 10 Hz, the measurement frequency points within the measurement frequency range can be set to 0.01 Hz, 10.01 Hz, 20.01 Hz, 30.01 Hz... etc. However, the method of selecting measurement frequency points in a fixed frequency step manner limits the flexibility of electrochemical impedance spectroscopy measurement, which may lead to the problem of missing electrochemical impedance information in some key frequency ranges. Summary of the Invention

[0004] In view of the above problems, embodiments of this application provide an electrochemical impedance measurement circuit, method, chip and electronic device to solve the above technical problems.

[0005] In a first aspect, an embodiment of this application provides an electrochemical impedance measurement circuit, which is used to measure the electrochemical impedance spectroscopy of an impedance module within a preset frequency range, and includes:

[0006] An excitation module, which is used to output an excitation signal, and the excitation signal is used to excite the impedance module to output a response signal;

[0007] A measurement module, which is used to determine the electrochemical impedance of the impedance module at the corresponding frequency according to the response signal corresponding to the frequency;

[0008] Wherein, the preset frequency range includes multiple sub-frequency ranges, and the frequency of the excitation signal within each sub-frequency range is determined according to the corresponding set frequency step, and at least two sub-frequency ranges have unequal corresponding set frequency steps.

[0009] Second aspect, the present application provides an electrochemical impedance measurement method, which is used to measure the electrochemical impedance spectrum of an impedance module within a preset frequency range. The preset frequency range includes multiple sub-frequency ranges. The method includes:

[0010] Output an excitation signal at a corresponding set frequency step in each sub-frequency range. The excitation signal is used to stimulate the impedance module to output a response signal;

[0011] Determine the electrochemical impedance of the impedance module at the corresponding frequency according to the response signal at the corresponding frequency;

[0012] Wherein, the frequency of the excitation signal within each sub-frequency range is determined according to the corresponding set frequency step, and the set frequency steps corresponding to at least two sub-frequency ranges are not equal.

[0013] Third aspect, an embodiment of the present application further provides a chip, including the above-mentioned electrochemical impedance measurement circuit.

[0014] Fourth aspect, an embodiment of the present application further provides an electronic device, including the above-mentioned chip or electrochemical impedance measurement circuit.

[0015] The present application stimulates the impedance module to output a response signal through the excitation signal output by the excitation module, so that the measurement module can determine the electrochemical impedance of the impedance module at the corresponding frequency according to the excitation signal and the response signal at the corresponding frequency. At the same time, since the frequency of the excitation signal within each sub-frequency range is determined according to the corresponding set frequency step, and the set frequency steps corresponding to at least two sub-frequency ranges are not equal, that is to say, the present application can set the set frequency step of a certain sub-frequency range according to actual needs, so as to select more or fewer measurement frequency points within that sub-frequency range, which is beneficial to improving the flexibility of electrochemical impedance spectrum measurement and avoiding the problem of missing electrochemical impedance information due to too few measurement points within some key frequency ranges.

[0016] These aspects or other aspects of the present application will be more clearly understood in the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 Shows a schematic diagram of an electrochemical impedance measurement circuit in an embodiment of the present application.

[0019] Figure 2Another schematic diagram of the electrochemical impedance measurement circuit in the embodiment of the present application is shown.

[0020] Figure 3 Another schematic diagram of the electrochemical impedance measurement circuit in the embodiment of the present application is shown.

[0021] Figure 4 A spectral schematic diagram of the excitation signal in the embodiment of the present application is shown.

[0022] Figure 5 Another spectral schematic diagram of the excitation signal in the embodiment of the present application is shown.

[0023] Figure 6 Another spectral schematic diagram of the excitation signal in the embodiment of the present application is shown.

[0024] Figure 7 Another schematic diagram of the electrochemical impedance measurement circuit in the embodiment of the present application is shown.

[0025] Figure 8 Another schematic diagram of the electrochemical impedance measurement circuit in the embodiment of the present application is shown.

[0026] Figure 9 Another schematic diagram of the electrochemical impedance measurement circuit in the embodiment of the present application is shown.

[0027] Figure 10 Another schematic diagram of the electrochemical impedance measurement circuit in the embodiment of the present application is shown.

[0028] Figure 11 A flowchart schematic diagram of the electrochemical impedance measurement method in the embodiment of the present application is shown.

[0029] Wherein, 1 is an impedance module, 100 is an electrochemical impedance measurement circuit, 10 is an excitation module, 20 is a measurement module, 11 is a signal generation unit, 111 is a DDS signal generator, 112 is a digital-to-analog converter, 113 is a low-pass filter, 114 is a MOS transistor drive circuit, 12 is a step control unit, 121 is a digital state machine, and 13 is a frequency detection unit;

[0030] The excitation signal ES, the response signal RS, the first set frequency step Δfa, and the second set frequency step Δfb. Specific embodiments

[0031] The following details the embodiments of the present application. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for explaining the present application and should not be construed as limiting the present application.

[0032] To enable those skilled in the art to better understand the solution of this application, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of this application.

[0033] In the embodiments of this application, it should be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0034] Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0035] In the description of the embodiments of this application, words such as "example" or "for example" are used to indicate examples, explanations or descriptions. Any embodiment or design solution described as "for example" or "example" in the embodiments of this application is not interpreted as being more preferred or having more advantages than another embodiment or design solution. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0036] In addition, "a plurality of" in the embodiments of this application means two or more. In view of this, "a plurality of" in the embodiments of this application can also be understood as "at least two". "At least one" can be understood as one or more, for example, understood as one, two or more. For example, including at least one means including one, two or more, and does not limit which ones are included. For example, including at least one of A, B and C, then what is included can be A, B, C, A and B, A and C, B and C, or A and B and C.

[0037] It should be pointed out that "connection" in the embodiments of this application can be understood as electrical connection, and the connection of two electrical components can be a direct or indirect connection between the two electrical components. For example, when A is connected to B, it can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0038] At present, the electrochemical impedance spectroscopy measurement method usually selects measurement frequency points in a fixed frequency step manner. For example, assuming that the measurement frequency range is 0.01 Hz to 10 kHz and the fixed frequency step is 10 Hz, then the measurement frequency points within the measurement frequency range can be set to 0.01 Hz, 10.01 Hz, 20.01 Hz, 30.01 Hz... etc. After the measurement is completed at each measurement frequency point, the impedance values of each measurement frequency point form the electrochemical impedance spectroscopy.

[0039] However, the method of selecting measurement frequency points in a fixed frequency step manner limits the flexibility of electrochemical impedance spectroscopy measurement. For example, when focusing on the impedance of the object under test in the low-frequency range, if the fixed frequency step is reduced, although more impedance measurement points can be obtained in the low-frequency range, this also leads to an increase in impedance measurement points in other frequency ranges, ultimately resulting in a large amount of time and power consumption for electrochemical impedance spectroscopy measurement.

[0040] Therefore, this application provides an electrochemical impedance measurement circuit, method, chip and electronic device, which will be described in detail below.

[0041] First, refer to Figure 1 , Figure 1 FIG. shows a schematic diagram of an electrochemical impedance measurement circuit 100 in an embodiment of this application. Among them, the electrochemical impedance measurement circuit 100 is used to measure the electrochemical impedance spectroscopy of the impedance module 1 within a preset frequency range (such as 0.01 Hz to 10 kHz). The electrochemical impedance measurement circuit 100 includes an excitation module 10 and a measurement module 20.

[0042] Specifically, the impedance module 1 refers to any module that has an obstructive effect on the alternating current passing through it. In some embodiments of this application, the impedance module 1 may include electronic components, such as resistors, capacitors, inductors or transistors, etc. Transistors such as MOS transistors, triodes, IGBT transistors or diodes, etc., so as to facilitate the analysis of the electrochemical impedance spectroscopy of electronic components through the electrochemical impedance measurement circuit 100. In some embodiments of this application, the impedance module 1 may include a battery or components of a battery. Batteries such as carbon-zinc batteries, alkaline batteries, lithium batteries, lead-acid batteries or nickel-metal hydride batteries, etc. Components of the battery such as electrodes or electrolytes (electrolyte solutions), etc., so as to facilitate the analysis of the electrochemical impedance spectroscopy of the battery and its components through the electrochemical impedance measurement circuit 100.

[0043] The excitation module 10 can input an excitation signal ES to the impedance module 1, so that the excitation impedance module 1 is excited by the excitation signal ES and outputs a response signal RS. Generally, the excitation module 10 can output excitation signals ES of different frequencies. Under the excitation of the excitation signals ES of different frequencies, the impedance module 1 can generate response signals RS of different frequencies. After the measurement module 20 measures the response signals RS of different frequencies, the electrochemical impedance of the impedance module 1 at different frequencies can be calculated. Therefore, the electrochemical impedances at different frequencies can be combined to form the electrochemical impedance spectrum of the impedance module 1.

[0044] In some embodiments of the present application, the excitation signal ES can be a signal for controlling the impedance module 1. For example, refer to Figure 2 , Figure 2 shows another schematic diagram of the electrochemical impedance measurement circuit 100 in an embodiment of the present application. The impedance module 1 includes a battery cell, a resistor R0, and an NMOS transistor M1. The excitation signal ES controls the NMOS transistor M1 to cause a current to be generated in the loop where the battery cell is located. At this time, the voltage of the battery cell and the current flowing through the resistor R0 are used as the response signal RS. After the measurement module 20 measures the voltage of the battery cell and the current flowing through the resistor R0, the electrochemical impedance of the battery cell can be calculated.

[0045] In some embodiments of the present application, the excitation signal ES can also be a voltage or current signal input to the impedance module 1. For example, refer to Figure 3 , Figure 3 shows another schematic diagram of the electrochemical impedance measurement circuit 100 in an embodiment of the present application. The impedance module 1 includes a battery cell, a first operational amplifier OP1, a second operational amplifier OP2, a first resistor R1, and a second resistor R2. Among them, the second operational amplifier OP2 acts as a voltage follower to make the reference electrode voltage of the battery cell equal to the voltage of the non-inverting input terminal of the first operational amplifier OP1, so as to ensure that the reference electrode of the battery cell is fixed without voltage drop; the excitation signal ES is input to the inverting input terminal of the first operational amplifier OP1, and a voltage is output through the output terminal of the first operational amplifier OP1 to excite the battery cell and generate a current. At this time, the output current of the battery cell is used as the response signal RS. After the measurement module 20 measures the output current of the battery cell, the electrochemical impedance of the battery cell can be calculated according to the voltage of the excitation signal ES and the current output by the battery cell.

[0046] In some embodiments of the present application, the excitation module 10 can output an excitation signal ES in a signal simulation manner. For example, after determining the AC voltage value of the excitation signal ES in the time domain, an analog voltage is output in sequence through a digital-to-analog converter, thereby achieving the purpose of analog output of the excitation signal ES. In some embodiments of the present application, the excitation module 10 can simulate and output the excitation signal ES through an oscillator, and generate an excitation signal ES with a corresponding frequency by controlling the oscillation frequency of the oscillator.

[0047] Exemplarily, the excitation signal ES can be, but is not limited to, an AC signal such as a sine signal, a cosine signal, or a square wave signal.

[0048] The measurement module 20 can measure the amplitude of the response signal RS, so as to determine the electrochemical impedance of the impedance module 1 at the corresponding frequency according to the response signal RS at the corresponding frequency. For example, Figure 2 taking the response signal including the voltage of the battery cell and the current flowing through the resistor R0 as an example, after measuring the voltage of the battery cell and the current flowing through the resistor R0, the impedance at the corresponding frequency can be calculated according to the following formula:

[0049]

[0050] where Z(fn) is the impedance of the impedance module 1 at the frequency fn, V1(fn) is the effective amplitude of the voltage of the battery cell at the corresponding frequency fn, V2(fn) is the effective amplitude of the current flowing through the resistor R0 at the corresponding frequency fn, R is the real part of the complex impedance, and X is the imaginary part of the complex impedance.

[0051] In some embodiments of the present application, the measurement module 20 can include an analog-to-digital converter and an impedance calculation circuit. The analog-to-digital converter can convert the response signal RS into a digital signal, and the impedance calculation circuit can perform a Fourier transform on the digital signal output by the analog-to-digital converter and obtain the frequency domain signal corresponding to the response signal RS, so as to calculate the electrical impedance value of the impedance module 1 at the corresponding frequency according to the frequency domain signal. Exemplarily, the analog-to-digital converter can be, but is not limited to, a successive approximation analog-to-digital converter (SAR ADC), a Sigma-Delta analog-to-digital converter (SD ADC), a pipeline analog-to-digital converter (Pipeline ADC), or a hybrid analog-to-digital converter composed of one or more of them.

[0052] In the embodiments of the present application, the preset frequency range includes multiple sub-frequency ranges. The frequency of the excitation signal ES in each sub-frequency range is determined according to the corresponding set frequency step, and the set frequency steps corresponding to at least two sub-frequency ranges are not equal.

[0053] For example, referring to Figure 4 , Figure 4 shows a spectrum schematic diagram of an excitation signal ES in an embodiment of the present application. Among them, the preset frequency range includes sub-frequency range 1, sub-frequency range 2, and sub-frequency range 3. Within sub-frequency range 1, the excitation module 10 outputs the excitation signal ES four times in total (that is, there are 4 measurement frequency points in sub-frequency range 1 in total). The frequencies of the four excitation signals ES are fx, fx + △fx, fx + 2△fx, and fx + 3△fx respectively. It can be seen that the frequency of the excitation signal ES within sub-frequency range 1 changes arithmetically with a set frequency step △fx.

[0054] Within sub-frequency range 2, the excitation module 10 outputs the excitation signal ES eight times in total (that is, there are 8 measurement frequency points in sub-frequency range 2 in total). The frequencies of the eight excitation signals ES are fy, fy + △fy, fy + 2△fy, fy + 3△fy, fy + 4△fy, fy + 5△fy, fy + 6△fy, and fy + 7△fy respectively. It can be seen that the frequency of the excitation signal ES within sub-frequency range 2 changes arithmetically with a set frequency step △fy.

[0055] Within sub-frequency range 3, the excitation module 10 outputs the excitation signal ES four times in total (that is, there are 4 measurement frequency points in sub-frequency range 3 in total). The frequencies of the four excitation signals ES are fz, fz + △fz, fz + 2△fz, and fz + 3△fz respectively. It can be seen that the frequency of the excitation signal ES within sub-frequency range 3 changes arithmetically with a set frequency step △fz.

[0056] In Figure 4 , the set frequency step △fy is the smallest, and the set frequency step △fx is equal to the set frequency step △fz. Therefore, the density of measurement frequency points in sub-frequency range 2 is higher than that in other sub-frequency ranges. More impedance measurement points of the impedance module 1 can be obtained within sub-frequency range 2. Therefore, while avoiding an increase in impedance measurement points in other sub-frequency ranges, the electrical impedance measurement effect of the impedance module 1 within sub-frequency range 2 can be ensured.

[0057] It should be noted that in the above embodiments, the frequencies of the excitation signal ES in each sub-frequency range change arithmetically according to the corresponding set frequency step. This embodiment is only an exemplary embodiment and is not limited thereto in practice. For example, the frequencies of the four excitation signals ES in the sub-frequency range 1 can also be fx, fx + 1Δfx, fx + 3Δfx, fx + 5Δfx respectively, where Δfx is the set frequency step corresponding to the sub-frequency range 1; for another example, the frequencies of the four excitation signals ES in the sub-frequency range 1 can also be fx, fx + 2Δfx, fx + 4Δfx, fx + 6Δfx respectively, where Δfx is the set frequency step corresponding to the sub-frequency range 1; for still another example, the frequencies of the four excitation signals ES in the sub-frequency range 1 can also be fx, fx + 1Δfx, fx + 2Δfx, fx + 4Δfx respectively, where Δfx is the set frequency step corresponding to the sub-frequency range 1.

[0058] Meanwhile, it should be pointed out that the above embodiments take the excitation module 10 outputting multiple excitation signals ES in each sub-frequency range as an example for exemplary illustration. In this embodiment, the excitation signal ES is usually a sine or cosine signal. At the same time, one excitation signal ES corresponds to one impedance measurement point of the impedance module 1, but it is not limited thereto. In some possible embodiments, the excitation module 10 can also output one excitation signal ES to the impedance module 1, and then measure multiple impedance measurement points of the impedance module 1 in a certain sub-frequency range. For example, when the excitation signal ES output by the excitation module 10 is a square wave signal, the square wave signal satisfies the following relationship:

[0059] s(t) = a0 + a1*sin(2π*f*t) + a2*sin(2π*2f*t) + a3*sin(2π*3f*t) +... an*sin(2π*nf*t)

[0060] where a1, a2, a3... an are the amplitudes of the respective sine signals, f, 2f, 3f... nf are the frequencies of the respective sine signals, and f to nf correspond to a certain sub-frequency range.

[0061] It can be seen that since the square wave signal is composed of the superposition of multiple sine signals, and the frequencies of these multiple sine signals change arithmetically according to the set frequency step f, at this time, it can be considered that the excitation module 10 is equivalent to inputting sine excitation signals with frequencies of f, 2f, 3f... nf to the impedance module 1 respectively. Therefore, the electrochemical impedance of the impedance module 1 at frequencies of f, 2f, 3f... nf can be measured.

[0062] In the embodiments of the present application, the present application uses the excitation signal ES output by the excitation module 10 to excite the impedance module 1 to output a response signal RS, so that the measurement module 20 can determine the electrochemical impedance of the impedance module 1 at the corresponding frequency according to the excitation signal ES and the response signal RS at the corresponding frequency. At the same time, since the frequency of the excitation signal ES in each sub-frequency range is determined according to the corresponding set frequency step, and the set frequency steps corresponding to at least two sub-frequency ranges are not equal, that is to say, the present application can set the set frequency step of a certain sub-frequency range according to actual needs, so as to select more or fewer measurement frequency points within the sub-frequency range, which is beneficial to improving the flexibility of electrochemical impedance spectroscopy measurement, while ensuring the number of measurement points in the key frequency range and avoiding the phenomenon of a large increase in measurement time and power consumption.

[0063] In some embodiments of the present application, the multiple sub-frequency ranges include a first sub-frequency range and a second sub-frequency range; the frequency of the excitation signal ES in the first sub-frequency range is determined according to the first set frequency step Δfa, and the frequency of the excitation signal ES in the second sub-frequency range is determined according to the second set frequency step Δfb; wherein, the upper limit frequency of the first sub-frequency range is less than or equal to the lower limit frequency of the second sub-frequency range, and the first set frequency step Δfa is less than the second set frequency step Δfb.

[0064] For example, refer to Figure 5 , Figure 5 shows another spectrum schematic diagram of the excitation signal ES in the embodiments of the present application. In Figure 5 , the frequency of the excitation signal ES in the first sub-frequency range changes arithmetically according to the first set frequency step Δfa, and the frequency of the excitation signal ES in the second sub-frequency range changes arithmetically according to the second set frequency step Δfb.

[0065] It should be noted that usually batteries are more sensitive to signals in the medium and low frequency ranges. Therefore, it is usually required to set a larger number of measurement frequency points in the medium and low frequency ranges. In the above embodiments, since the upper limit frequency of the first sub-frequency range is less than or equal to the lower limit frequency of the second sub-frequency range, and at the same time the first set frequency step Δfa is less than the second set frequency step Δfb, relatively speaking, the first sub-frequency range corresponds to the medium and low frequency ranges, while the second sub-frequency range corresponds to the high frequency range. In the case where the first set frequency step Δfa is less than the second set frequency step Δfb, the first sub-frequency range is set with a relatively high density of measurement frequency points, and the second sub-frequency range is set with a relatively low density of measurement frequency points, which is beneficial to ensuring the measurement effect of the electrochemical impedance of the battery in the medium and low frequency ranges.

[0066] It can be understood that Figure 5In the embodiments shown, the frequencies of the excitation signal ES within the first sub-frequency range and the second sub-frequency range change arithmetically with corresponding frequency steps. In fact, it is not limited to this. For example, the frequency of the excitation signal ES within the first sub-frequency range changes geometrically with the first set frequency step Δfa; for another example, the frequency of the excitation signal ES within the second sub-frequency range changes geometrically with the second set frequency step Δfb; for still another example, the frequency of the excitation signal ES within the first sub-frequency range changes as 1 times Δfa, 2 times Δfa, 3 times Δfa, 5 times Δfa, 8 times Δfa...

[0067] In some embodiments of the present application, the excitation signal ES output by the excitation module 10 within the first sub-frequency range is a square wave signal; the excitation signal ES output by the excitation module 10 within the second sub-frequency range is a sine wave signal.

[0068] It should be noted that since the square wave signal is composed of the superposition of multiple sine signals with different frequencies, when the excitation module 10 outputs a square wave signal as the excitation signal ES within the first sub-frequency range, it can be considered that the excitation module 10 inputs multiple sine signals with different frequencies to the impedance module 1. At this time, the purpose of measuring the electrochemical impedance of multiple frequency points within the first sub-frequency range of the impedance module 1 can be achieved by one excitation. At the same time, since relatively speaking, the first sub-frequency range is the medium and low frequency domain, and the second sub-frequency range is the high frequency domain, when the excitation module 10 outputs a sine wave signal as the excitation signal ES within the second sub-frequency range, it can avoid the phenomenon that the bandwidth requirement of the measurement module 20 becomes higher when a square wave signal is used for excitation in the medium and high frequency domain, thereby increasing the power consumption of the electrochemical impedance measurement circuit 100.

[0069] In some embodiments of the present application, the magnitude of the set frequency step is positively correlated with the upper limit frequency of the sub-frequency range.

[0070] For example, refer to Figure 6 , Figure 6 shows another spectrum schematic diagram of the excitation signal ES in the embodiments of the present application. Among them, multiple sub-frequency ranges include sub-frequency range 1... sub-frequency range m... sub-frequency range n, and the upper limit frequency of sub-frequency range 1 < the upper limit frequency of sub-frequency range m < the upper limit frequency of sub-frequency range n, and the set frequency step Δf1 of sub-frequency range 1 < the set frequency step Δfm of sub-frequency range 1 < the set frequency step Δfn of sub-frequency range 1.

[0071] It can be seen that as the frequency in the sub - frequency range increases, the set frequency step corresponding to the sub - frequency range increases. Therefore, after obtaining the electrochemical impedance spectrum, the electrochemical impedance spectrum has a high - density impedance measurement points in the low - frequency domain (e.g., 0.01 Hz to 100 Hz), an appropriate - density impedance measurement points in the mid - frequency domain (e.g., 100 Hz to 1 kHz), and a low - density impedance measurement points in the high - frequency domain (e.g., 1 kHz to 10 kHz), thereby ensuring that the impedance module 1 has good electrochemical impedance measurement effects in each sub - frequency range.

[0072] In some embodiments of the present application, referring to Figure 7 , Figure 7 shows another schematic diagram of the electrochemical impedance measurement circuit 100 in the embodiments of the present application. Among them, the excitation module 10 includes a signal generation unit 11 and a step - size control unit 12.

[0073] Specifically, the signal generation unit 11 can output an excitation signal ES according to the set frequency step. The set frequency step can be stored as a parameter in the storage circuit (such as a register) of the signal generation unit 11. After the signal generation unit 11 reads the set frequency step stored in the storage circuit, it can output an excitation signal ES whose frequency changes arithmetically according to the set frequency step. For example, taking Figure 4 as an example, during the process of the signal generation unit 11 outputting the excitation signal ES in the sub - frequency range 1, the frequency of the first excitation signal ES output by the signal generation unit 11 is fx, the frequency of the second excitation signal ES is fx + △fx, the frequency of the third excitation signal ES is fx + 1△fx... and so on. The excitation signals ES in other sub - frequency ranges are the same and will not be elaborated here.

[0074] The step - size control unit 12 is used to output a step - size control signal to the signal generation unit 11, and the step - size control signal is used to control the magnitude of the set frequency step. For example, taking Figure 4 as an example, when it is necessary to output the excitation signal ES in the sub - frequency range 1, the step - size control unit 12 can output a step - size control signal to the signal generation unit 11. Under the control of the step - size control signal, the magnitude of the set frequency step stored in the storage circuit is rewritten as △fx, so that the frequency of the excitation signal ES in the sub - frequency range 1 changes arithmetically according to the set frequency step △fx; similarly, when it is necessary to output the excitation signal ES in other sub - frequency ranges, the step - size control unit 12 outputs a step - size control signal to control the set frequency step stored in the storage circuit to be rewritten as the corresponding magnitude.

[0075] In some embodiments of the present application, referring to Figure 8 , Figure 8Another schematic diagram of the electrochemical impedance measurement circuit 100 in the embodiments of the present application is shown, where the step control unit 12 includes a digital state machine 121.

[0076] It should be noted that the digital state machine 121 has multiple working states. Among them, the data stored in the register of the digital state machine 121 can represent the working state in which the digital state machine 121 is located. For example, when the data stored in the register is "0000", it can represent that the digital state machine 121 is in a certain working state. When the data stored in the register is "0001", it can represent that the digital state machine 121 is in another working state.

[0077] During the operation of the digital state machine 121, the digital state machine 121 can switch working states in a preset order. For example, the digital state machine 121 can switch working states in the order of "0000", "0001", "0010", "0011", "0100"... "1111"; or for another example, the digital state machine 121 can switch working states in the order of "1111", "1110", "1100", "1011", "1010"... "0000".

[0078] In each working state, the digital state machine 121 can output a step control signal to facilitate the control signal generating unit 11 to output the excitation signal ES according to the corresponding set frequency step. For example, when the digital state machine 121 is in the working state "0000", the step control signal output by the digital state machine 121 can control the control signal generating unit 11 to output the excitation signal ES according to the set frequency step of 10 hz; when the digital state machine 121 is in the working state "0001", the step control signal output by the digital state machine 121 can control the control signal generating unit 11 to output the excitation signal ES according to the set frequency step of 20 hz; when the digital state machine 121 is in the working state "0010", the step control signal output by the digital state machine 121 can control the control signal generating unit 11 to output the excitation signal ES according to the set frequency step of 100 hz, and so on, which will not be elaborated here.

[0079] It can be seen that since the digital state machine 121 can switch working states in a preset order, the digital state machine 121 can control the magnitude of the set frequency step of the control signal generating unit 11 in a preset order, so that the frequency of the excitation signal ES is determined according to the corresponding set frequency step in each sub-frequency range.

[0080] In some embodiments of the present application, refer to Figure 9 , Figure 9Another schematic diagram of the electrochemical impedance measurement circuit 100 in the embodiment of the present application is shown. Among them, the step control unit 12 includes a frequency detection unit 13. The frequency detection unit 13 can detect the frequency of the excitation signal ES, and can output an enable signal to the digital state machine 121 when the frequency of the excitation signal ES reaches the upper limit frequency of any sub-frequency range, so as to control the digital state machine 121 to switch to the next working state through the enable signal.

[0081] For example, taking Figure 4 as an example, when the frequency detection unit 13 detects that the frequency of the excitation signal ES is fx + 3△fx, it indicates that the frequency of the excitation signal ES reaches the upper limit frequency of the sub-frequency range 1. Therefore, the frequency detection unit 13 can output an enable signal to the digital state machine 121, so that the digital state machine 121 switches from the working state "0000" to the working state "0001". Therefore, the digital state machine 121 can output a step control signal to the signal generation unit 11 to change the set frequency step of the signal generation unit 11 to △fy.

[0082] When the frequency detection unit 13 detects that the frequency of the excitation signal ES is fy + 7△fx, it indicates that the frequency of the excitation signal ES reaches the upper limit frequency of the sub-frequency range 2. Therefore, the frequency detection unit 13 can output an enable signal to the digital state machine 121 again, so that the digital state machine 121 switches from the working state "0001" to the working state "0011". Therefore, the digital state machine 121 can output a step control signal to the signal generation unit 11 to change the set frequency step of the signal generation unit 11 to △fz.

[0083] It can be seen that whenever the frequency detection unit 13 detects that the frequency of the excitation signal ES reaches the upper limit frequency of a certain sub-frequency range, the frequency detection unit 13 can output an enable signal to the digital state machine 121, so as to control the digital state machine 121 to switch to the next working state, and finally change the set frequency step of the signal generation unit 11 through the step control signal output by the digital state machine 121.

[0084] It can be understood that the above embodiment exemplarily illustrates how to control the set frequency step of the excitation signal ES within each sub-frequency range in the way of feedback control of the digital state machine 121. In some possible embodiments, the digital state machine 121 can also actively switch the working state. For example, assuming that the electrochemical impedance measurement time for each sub-frequency range is 2 seconds, then the digital state machine 121 can record the time since the last output of the step control signal through a timer, and the digital state machine 121 can switch to the next working state when the timer reaches 2 seconds.

[0085] As an exemplary embodiment of the signal generation unit 11, refer to Figure 10 , Figure 10Another schematic diagram of the electrochemical impedance measurement circuit 100 in the embodiment of the present application is shown. Among them, the signal generation unit 11 may include a DDS signal generator 111, a digital-to-analog converter 112, a low-pass filter 113, and a MOS transistor drive circuit 114. When the signal generation unit 11 operates, the DDS signal generator 111 outputs a digital signal to the digital-to-analog converter 112. The digital-to-analog converter 112 converts the digital signal into an analog voltage in sequence and forms a sine AC voltage signal or a square wave AC voltage signal. After being filtered by the low-pass filter 113 and passing through the MOS transistor drive circuit 114, an excitation signal ES for controlling the NMOS transistor M1 can be output.

[0086] To better implement the electrochemical impedance measurement circuit 100 in the embodiment of the present application, based on the electrochemical impedance measurement circuit 100, the present application also provides an electrochemical impedance measurement method. Refer to Figure 11 , Figure 11 A flowchart of an electrochemical impedance measurement method in the embodiment of the present application is shown. Among them, the electrochemical impedance measurement method includes:

[0087] Step S1101: Output an excitation signal ES at a corresponding set frequency step in each sub-frequency range. The excitation signal ES is used to excite the impedance module 1 to output a response signal RS;

[0088] Step S1102: Determine the electrochemical impedance of the impedance module 1 at the corresponding frequency according to the response signal RS at the corresponding frequency.

[0089] The electrochemical impedance measurement method of the present application divides the preset frequency range into multiple sub-frequency ranges. The frequency of the excitation signal ES in each sub-frequency range is determined according to the corresponding set frequency step, and the set frequency steps corresponding to at least two sub-frequency ranges are not equal. That is to say, the present application can set the set frequency step of a certain sub-frequency range according to actual needs, so as to select more or fewer measurement frequency points in that sub-frequency range, which is beneficial to improving the flexibility of electrochemical impedance spectroscopy measurement and avoiding the problem of missing electrochemical impedance information due to too few measurement points in some key frequency ranges.

[0090] The embodiment of the present application also provides a chip, and the chip includes the above-mentioned electrochemical impedance measurement circuit 100. A chip (Integrated Circuit, IC) is also called a chip, and the chip can be but is not limited to a SOC (System on Chip, chip-level system) chip, a SIP (system in package, system-level package) chip. Since the chip of the present application has the above-mentioned electrochemical impedance measurement circuit 100 in the above-mentioned embodiment, it has all the beneficial effects of the electrochemical impedance measurement circuit 100 in the above-mentioned embodiment, and will not be elaborated here.

[0091] The embodiment of the present application further provides an electronic device, which includes a device body and the above-mentioned chip disposed in the device body. Among them, the electronic device may include a Battery Management System (BMS). For example, the electronic device may be, but is not limited to, an electric vehicle, an energy storage system, a mobile power supply, a drone, a power tool, a robot, a smart home device, etc. with a battery management system. The electric vehicle may be, but is not limited to, a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a range-extended electric vehicle (REEV), or a fuel cell electric vehicle (FCEV). The smart home device may include, but is not limited to, a smart floor sweeper, a smart floor washer, a smart window cleaning robot, etc.

[0092] The above are only the preferred embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application has been disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the technical content disclosed above without departing from the technical solution scope of the present application. However, as long as it does not depart from the technical solution content of the present application, any brief modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present application still fall within the scope of the technical solution of the present application.

Claims

1. An electrochemical impedance measurement circuit, characterized in that, The electrochemical impedance measurement circuit is used to measure the electrochemical impedance spectrum of an impedance module within a preset frequency range, and includes: An excitation module, which is used to output an excitation signal for exciting the impedance module to output a response signal; A measurement module, which is used to determine the electrochemical impedance of the impedance module at the corresponding frequency according to the response signal at the corresponding frequency; Wherein, the preset frequency range includes a plurality of sub-frequency ranges, and the frequency of the excitation signal within each sub-frequency range is determined according to the corresponding set frequency step, and at least two of the set frequency steps corresponding to the sub-frequency ranges are not equal.

2. The electrochemical impedance measurement circuit according to claim 1, characterized in that, The frequency of the excitation signal within each sub-frequency range changes arithmetically according to the corresponding set frequency step.

3. The electrochemical impedance measurement circuit according to claim 1, characterized in that, The plurality of sub-frequency ranges include a first sub-frequency range and a second sub-frequency range; The frequency of the excitation signal within the first sub-frequency range is determined according to the first set frequency step, and the frequency of the excitation signal within the second sub-frequency range is determined according to the second set frequency step; Wherein, the upper limit frequency of the first sub-frequency range is less than or equal to the lower limit frequency of the second sub-frequency range, and the first set frequency step is less than the second set frequency step.

4. The electrochemical impedance measurement circuit according to claim 3, wherein The frequency of the excitation signal within the first sub-frequency range changes arithmetically according to the first set frequency step; The frequency of the excitation signal within the second sub-frequency range changes arithmetically according to the second set frequency step.

5. The electrochemical impedance measurement circuit according to claim 3, wherein The excitation signal output by the excitation module within the first sub-frequency range is a square wave signal; The excitation signal output by the excitation module within the second sub-frequency range is a sine wave signal.

6. The electrochemical impedance measurement circuit according to claim 1, wherein The magnitude of the set frequency step is positively correlated with the upper limit frequency of the sub-frequency range.

7. The electrochemical impedance measurement circuit according to claim 1, characterized in that, The excitation module includes a step control unit and a signal generation unit; The signal generation unit is used to output the excitation signal according to the set frequency step; The step control unit is used to output a step control signal to the signal generation unit, and the step control signal is used to control the magnitude of the set frequency step.

8. The electrochemical impedance measurement circuit according to claim 7, wherein The step control unit includes a digital state machine; The digital state machine has a plurality of working states, and is used to switch the working states in a preset order and output the step control signal in each working state.

9. The electrochemical impedance measurement circuit according to claim 8, wherein, The step control unit includes a frequency detection unit; The frequency detection unit is used to output an enable signal to the digital state machine when the frequency of the excitation signal reaches the upper limit frequency of any sub-frequency range, and the enable signal is used to control the digital state machine to switch to the next working state in the preset order.

10. An electrochemical impedance measurement method, characterized in that, The electrochemical impedance measurement method is used to measure the electrochemical impedance spectrum of an impedance module within a preset frequency range, and the preset frequency range includes a plurality of sub-frequency ranges. The method includes: Outputting an excitation signal within each sub-frequency range according to the corresponding set frequency step, and the excitation signal is used to excite the impedance module to output a response signal; Determining the electrochemical impedance of the impedance module at the corresponding frequency according to the response signal at the corresponding frequency; Wherein, the frequency of the excitation signal in each of the sub-frequency ranges is determined according to a corresponding set frequency step, and the set frequency steps corresponding to at least two of the sub-frequency ranges are not equal.

11. A chip, characterized in that, Comprising the electrochemical impedance measurement circuit according to any one of claims 1 to 9.

12. An electronic device, characterized in that, Comprising the chip according to claim 11.

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