A method and device for measuring battery AC impedance spectrum

Abstract

The present invention discloses a method and device for measuring the AC impedance spectrum of a battery. The method obtains a battery operating waveform, determines the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum based on the battery operating waveform, establishes a battery equivalent circuit model using at least one of the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum, and determines the battery AC impedance spectrum based on the frequency response of the battery equivalent circuit model. It can be seen that the present invention does not require the addition of external AC excitation, and can obtain the battery AC impedance spectrum by constructing a battery equivalent circuit model using the battery operating waveform. This method not only has low hardware cost and is easy to implement, but also has a fast measurement speed for the battery AC impedance spectrum. The battery equivalent circuit model can also be used to implement online monitoring of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and more particularly to a method and device for measuring an AC impedance spectrum of a battery. Background Art

[0002] Battery AC impedance spectroscopy, also known as electrochemical impedance spectroscopy (EIS), can be used to analyze the dynamic processes and mechanisms of the battery system, identify battery anomalies, determine battery consistency, and monitor the battery's SOC (State of Charge) and temperature online.

[0003] The existing testing method for battery AC impedance spectrum is mainly as follows: when the battery is disturbed by an AC excitation signal with a sinusoidal waveform voltage (current), the battery will generate a corresponding current (voltage) response signal. The impedance of the battery electrode can be obtained based on the AC excitation signal and the response signal, thereby forming an AC impedance spectrum generated by a series of sinusoidal wave signals, that is, the battery AC impedance spectrum.

[0004] However, the existing battery AC impedance spectrum testing method requires adding external AC excitation to obtain the response, the equipment is expensive, the measurement time is long, and it is difficult to apply online. Summary of the Invention

[0005] In view of this, the present invention discloses a method and device for measuring the AC impedance spectrum of a battery, so that the battery AC impedance spectrum can be obtained by constructing a battery equivalent circuit model using the battery operating waveform without adding external AC excitation. Not only is the hardware cost low and easy to implement, but the battery AC impedance spectrum can also be measured quickly. The battery equivalent circuit model can also be used to realize online monitoring of the battery.

[0006] A method for measuring an AC impedance spectrum of a battery, comprising:

[0007] Get battery working waveform;

[0008] Determining a battery inductance, a battery ohmic internal resistance, and a relaxation time distribution spectrum based on the battery operating waveform;

[0009] Establishing a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum;

[0010] The battery AC impedance spectrum is determined according to the frequency response of the battery equivalent circuit model.

[0011] Optionally, the process of determining the battery inductance based on the battery operating waveform includes:

[0012] Determining a transient pulse peak based on the battery operating waveform;

[0013] The corresponding battery inductance is determined according to the transient instantaneous pulse peak.

[0014] Optionally, the process of determining the battery ohmic internal resistance and the relaxation time distribution spectrum based on the battery operating waveform includes:

[0015] Determining a battery dynamic DC internal resistance based on the battery operating waveform;

[0016] Directly obtaining the battery ohmic internal resistance from the battery dynamic DC internal resistance;

[0017] The component of the battery ohmic internal resistance is removed from the battery dynamic DC internal resistance, and a deconvolution operation is performed on the remaining battery impedance to obtain the relaxation time distribution spectrum.

[0018] Optionally, the process of determining the dynamic DC internal resistance of the battery based on the battery operating waveform includes:

[0019] Determining a transient pulse peak based on the battery operating waveform, wherein the transient pulse peak is generated based on the battery inductance;

[0020] Determine a battery characteristic fitting line based on performance parameters within a preset time period after the battery transient state ends;

[0021] Replacing the transient pulse peak with the battery characteristic fitting line to obtain a target battery characteristic curve;

[0022] The dynamic DC internal resistance of the battery is obtained based on the battery voltage and battery current corresponding to each moment in the target battery characteristic curve.

[0023] Optionally, the expression of the dynamic DC internal resistance of the battery is as follows:

[0024]

[0025] Wherein, z(t) represents the dynamic DC internal resistance of the battery, R0 represents the ohmic internal resistance of the battery, γ represents the relaxation time distribution spectrum, exp() represents the exponential function, t represents the time domain time, and τ represents the time constant.

[0026] Optionally, the battery operating waveform includes: a battery discharge waveform and / or a battery charge waveform in the time domain;

[0027] The battery discharge waveform includes: a start discharge waveform and / or a stop discharge waveform during the battery discharge process;

[0028] The battery charging waveform includes: an initial charging waveform and / or an end charging waveform during the battery charging process.

[0029] Optionally, determining the battery AC impedance spectrum according to the frequency response of the battery equivalent circuit model includes:

[0030] Using the battery equivalent circuit model as a transfer function, calculating a response output of the transfer function at different frequencies, wherein the response output includes a real part and an imaginary part in a complex space;

[0031] The real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

[0032] Optionally, the relaxation time distribution spectrum includes: a plurality of resistor-capacitor pairs connected in series, each of the resistor-capacitor pairs consisting of a capacitor and a resistor connected in parallel.

[0033] A device for measuring the AC impedance spectrum of a battery, comprising:

[0034] An acquisition unit, used for acquiring a battery operating waveform;

[0035] a first determining unit, configured to determine a battery inductance, a battery ohmic internal resistance, and a relaxation time distribution spectrum based on the battery operating waveform;

[0036] a model building unit, configured to build a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum;

[0037] The second determining unit is configured to determine the battery AC impedance spectrum according to the frequency response of the battery equivalent circuit model.

[0038] Optionally, the first determining unit includes:

[0039] a pulse peak determination subunit, configured to determine a transient instantaneous pulse peak based on the battery operating waveform;

[0040] The battery inductance determination subunit is configured to determine the corresponding battery inductance according to the transient instantaneous pulse peak.

[0041] Optionally, the first determining unit further includes:

[0042] a DC internal resistance determination subunit, configured to determine a battery dynamic DC internal resistance based on the battery operating waveform;

[0043] an ohmic internal resistance determination subunit, configured to directly obtain the battery ohmic internal resistance from the battery dynamic DC internal resistance;

[0044] The relaxation time distribution spectrum determination subunit is used to remove the component of the battery ohmic internal resistance from the battery dynamic DC internal resistance and perform a deconvolution operation on the remaining battery impedance to obtain the relaxation time distribution spectrum.

[0045] Optionally, the DC internal resistance determination subunit is specifically configured to:

[0046] Determining a transient pulse peak based on the battery operating waveform, wherein the transient pulse peak is generated based on the battery inductance;

[0047] Determine a battery characteristic fitting line based on performance parameters within a preset time period after the battery transient state ends;

[0048] Replacing the transient pulse peak with the battery characteristic fitting line to obtain a target battery characteristic curve;

[0049] The dynamic DC internal resistance of the battery is obtained based on the battery voltage and battery current corresponding to each moment in the target battery characteristic curve.

[0050] Optionally, the second determining unit is specifically configured to:

[0051] Using the battery equivalent circuit model as a transfer function, calculating a response output of the transfer function at different frequencies, wherein the response output includes a real part and an imaginary part in a complex space;

[0052] The real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

[0053] As can be seen from the above technical solution, the present invention discloses a method and device for measuring the AC impedance spectrum of a battery, which obtains the battery operating waveform, determines the battery inductance, battery ohmic internal resistance and relaxation time distribution spectrum based on the battery operating waveform, establishes a battery equivalent circuit model using at least one of the battery inductance, battery ohmic internal resistance and relaxation time distribution spectrum, and determines the battery AC impedance spectrum based on the frequency response of the battery equivalent circuit model. It can be seen from this that the present invention does not require the addition of external AC excitation, and can obtain the battery AC impedance spectrum by constructing a battery equivalent circuit model using the battery operating waveform. Not only is the hardware cost low and easy to implement, but the battery AC impedance spectrum has a fast measurement speed, and the battery equivalent circuit model can also be used to achieve online monitoring of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0055] Figure 1 A flow chart of a method for measuring the AC impedance spectrum of a battery disclosed in an embodiment of the present invention;

[0056] Figure 2 A typical battery AC impedance spectrum test circuit diagram disclosed in an embodiment of the present invention;

[0057] Figure 3 This is a typical current and voltage waveform diagram of a battery during discharge disclosed in an embodiment of the present invention;

[0058] Figure 4 A schematic diagram of a battery equivalent circuit model disclosed in an embodiment of the present invention;

[0059] Figure 5 This is a flow chart of a method for determining battery inductance based on a battery operating waveform disclosed in an embodiment of the present invention;

[0060] Figure 6 The instantaneous current and voltage waveforms of a battery discharge disclosed in an embodiment of the present invention;

[0061] Figure 7 A flow chart of a method for determining a battery's ohmic internal resistance and the relaxation time distribution spectrum based on a battery operating waveform disclosed in an embodiment of the present invention;

[0062] Figure 8 A waveform diagram of the dynamic DC internal resistance of a battery under an exponential coordinate system disclosed in an embodiment of the present invention;

[0063] Figure 9 A schematic diagram of a relaxation time distribution spectrum of a battery disclosed in an embodiment of the present invention;

[0064] Figure 10 This is a flow chart of a method for determining a battery's dynamic DC internal resistance based on a battery operating waveform disclosed in an embodiment of the present invention;

[0065] Figure 11 A comparison chart of a battery AC impedance spectrum obtained by the present invention and a battery AC impedance spectrum obtained by a traditional solution disclosed in an embodiment of the present invention;

[0066] Figure 12 The present invention provides a schematic structural diagram of a device for measuring the AC impedance spectrum of a battery according to an embodiment of the present invention. DETAILED DESCRIPTION

[0067] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0068] The embodiments of the present invention disclose a method and device for measuring the AC impedance spectrum of a battery. The method obtains a battery operating waveform, determines the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum based on the battery operating waveform, establishes a battery equivalent circuit model using at least one of the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum, and determines the battery AC impedance spectrum based on the frequency response of the battery equivalent circuit model. It can be seen that the present invention does not require the addition of external AC excitation, and can obtain the battery AC impedance spectrum by constructing a battery equivalent circuit model using the battery operating waveform. This method not only has low hardware cost and is easy to implement, but also has a fast measurement speed for the battery AC impedance spectrum. The battery equivalent circuit model can also be used to achieve online monitoring of the battery.

[0069] See also Figure 1 , a flow chart of a method for measuring a battery AC impedance spectrum disclosed in an embodiment of the present invention, the method comprising:

[0070] Step S101, obtaining a battery operating waveform;

[0071] In this embodiment, the battery operating waveform may include: a battery discharging waveform and / or a battery charging waveform in the time domain.

[0072] The battery discharge waveform includes: an initial discharge waveform and / or an end discharge waveform during the battery discharge process.

[0073] The battery charging waveform includes: an initial charging waveform and / or an end charging waveform during the battery charging process.

[0074] The battery operating waveform in this embodiment can be any one or a combination of the following: the initial discharge waveform and the final discharge waveform during the battery discharge process; and the initial charge waveform and the final charge waveform during the battery charge process. In other words, any one or any combination of the above four waveforms can be used as the battery operating waveform in this embodiment to obtain the final battery AC impedance spectrum.

[0075] Among them, the battery working waveform can be obtained by Figure 2 A typical battery AC impedance spectrum test circuit diagram is shown, which includes: battery LIB, switch S1 and resistor R bTaking the initial discharge waveform of the battery discharge process as an example, by closing the switch S1, the battery LIB is connected to the resistor R b Discharge, you can get the initial discharge waveform of the battery LIB. In practical applications, you can use various test methods to get the voltage V across the battery during the discharge process of the battery LIB. b And the discharge current I b See Figure 3 The typical battery discharge current and voltage waveforms are shown in Figure 3 In the figure, the horizontal axis represents time (unit: S), the vertical axis on the left represents the voltage across the battery (unit: V), and the vertical axis on the right represents the current (unit: A).

[0076] Step S102: determining the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum based on the battery operating waveform;

[0077] It should be noted that in the existing scheme, the relaxation time distribution spectrum can only be obtained by first obtaining the battery AC impedance spectrum through equipment such as an electrochemical workstation, and then inversely obtaining the relaxation time distribution spectrum. The relaxation time distribution spectrum in the present invention is directly determined based on the battery operating waveform. Therefore, compared with the relaxation time distribution spectrum obtained by inverse inference, it has higher accuracy, thereby improving the accuracy of the subsequent determination of the battery AC impedance spectrum to a certain extent.

[0078] Step S103: establishing a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum;

[0079] In practical applications, a battery equivalent circuit model can be constructed using any one of the following parameters: battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum, or a combination of these. When the battery equivalent circuit model is constructed using all three parameters, the accuracy of the battery equivalent circuit model is relatively high.

[0080] In this embodiment, the relaxation time distribution spectrum of the battery can be discretized into any number of series-connected resistor-capacitor pairs (RCpairs). That is, the relaxation time distribution spectrum includes multiple series-connected resistor-capacitor pairs, each of which is composed of a capacitor and a resistor connected in parallel.

[0081] All resistor and capacitor pairs, the battery inductance L0 and the battery ohmic internal resistance R0 together constitute a battery equivalent circuit model.

[0082] See Figure 4The battery equivalent circuit model is shown in the figure. The battery equivalent circuit model includes: a battery inductor L0, a battery ohmic internal resistance R0, and n resistor and capacitor pairs. The battery inductor L0, the battery ohmic internal resistance R0, and the n resistor and capacitor pairs are connected in series in sequence to form the battery equivalent circuit model. The n resistor and capacitor pairs include: a first resistor and capacitor pair formed by connecting a resistor R1 and a capacitor C1 in parallel, a second resistor and capacitor pair formed by connecting a resistor R2 and a capacitor C2 in parallel, ..., a resistor R n and capacitor C n The nth resistor and capacitor pair is connected in parallel.

[0083] Step S104: determining the battery AC impedance spectrum according to the frequency response of the battery equivalent circuit model.

[0084] Specifically, the battery equivalent circuit model is used as a transfer function, and the response output of the transfer function at different frequencies is calculated, wherein the response output includes a real part and an imaginary part in a complex space. Finally, the real part and the imaginary part of the response output are formed into a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

[0085] In summary, the present invention discloses a method for measuring the AC impedance spectrum of a battery, obtains a battery operating waveform, determines the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum based on the battery operating waveform, establishes a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum, and determines the battery AC impedance spectrum based on the frequency response of the battery equivalent circuit model. It can be seen from this that the present invention does not need to add external AC excitation, and the battery AC impedance spectrum can be obtained by constructing a battery equivalent circuit model using the battery operating waveform. Not only is the hardware cost low and easy to implement, but the battery AC impedance spectrum has a fast measurement speed, and the battery equivalent circuit model can also be used to achieve online monitoring of the battery.

[0086] In addition, the relaxation time distribution spectrum in the present invention is directly determined based on the battery operating waveform, thereby improving the accuracy of the constructed battery equivalent circuit model and further improving the measurement accuracy of the battery AC impedance spectrum.

[0087] To further optimize the above embodiment, see Figure 5 The present invention also discloses a flow chart of a method for determining battery inductance based on a battery operating waveform, the method comprising:

[0088] Step S201: determining a transient pulse peak based on a battery operating waveform;

[0089] Step S202: Determine the corresponding battery inductance according to the transient pulse peak.

[0090] Taking the battery discharge waveform as an example, the process of determining the battery inductance is explained as follows:

[0091] See also Figure 6 The instantaneous current and voltage waveforms of a battery discharge disclosed in an embodiment of the present invention are shown in Figure 1. The horizontal axis represents the time (unit: S), the vertical axis on the left represents the voltage across the battery (unit: V), and the vertical axis on the right represents the current (unit: A). Figure 2 At the moment switch S1 is closed, the current changes, and the inductor inside the battery induces the current change. At this time, it enters the sensing area. The time in the sensing area is t on , that is, t on It represents the transient time interval induced by the battery inductance after the switch S1 is closed.

[0092] This embodiment mainly infers the battery inductance L0 based on the voltage spike (ie, transient pulse spike) induced by the battery inductance when the current changes.

[0093] Among them, when the battery working waveform is the battery charging waveform, the principle of determining the battery inductance is the same as Figure 6 Similar, no further description is given here.

[0094] To further optimize the above embodiment, the present invention also discloses a process for determining the battery ohmic internal resistance and the relaxation time distribution spectrum based on the battery operating waveform, see Figure 7 , the method comprises the steps of:

[0095] Step S301: determining the dynamic DC internal resistance of the battery based on the battery operating waveform;

[0096] In practical applications, the battery characteristic fitting line can be used to replace the voltage spike caused by the battery inductance (see Figure 6 ), and divide the battery voltage by the battery current to get the battery dynamic DC internal resistance. Figure 8 The waveform of the battery's dynamic DC internal resistance under the exponential coordinates shown.

[0097] Step S302: directly obtaining the battery ohmic internal resistance from the battery dynamic DC internal resistance;

[0098] Step S303: removing the battery ohmic internal resistance component from the battery dynamic DC internal resistance, and performing a deconvolution operation on the remaining battery impedance to obtain a relaxation time distribution spectrum.

[0099] Specifically, Figure 8 After removing the battery ohmic internal resistance component from the battery dynamic DC internal resistance, the battery relaxation time distribution spectrum γ can be obtained through deconvolution operation. Figure 9Schematic diagram of the relaxation time distribution spectrum of the battery shown. In practical applications, the deconvolution operation method can be Fourier decomposition, wavelet analysis and other methods.

[0100] In summary, the present invention uses only one deconvolution operation to obtain the relaxation time distribution spectrum of the battery. Compared with the existing scheme that requires separate spectrum analysis of voltage and current and at least two or more Fourier decomposition (or wavelet analysis, etc.) similar operations, the present invention reduces the energy consumption when determining the relaxation time distribution spectrum.

[0101] Furthermore, the present invention determines the relaxation time distribution spectrum during the acquisition of the battery's AC impedance spectrum, which is extremely important for battery analysis and interpretation. Compared to the prior art, which requires only obtaining the battery's AC impedance spectrum using equipment such as an electrochemical workstation and then inferring the relaxation time distribution spectrum, the relaxation time distribution spectrum in the present invention is determined directly based on the battery's operating waveform, thereby improving the accuracy of the constructed battery equivalent circuit model and, in turn, the measurement accuracy of the battery's AC impedance spectrum.

[0102] To further optimize the above embodiment, see Figure 10 , a flow chart of a method for determining a battery's dynamic DC internal resistance based on a battery operating waveform disclosed in an embodiment of the present invention, the method comprising:

[0103] Step S401: determining a transient pulse peak based on a battery operating waveform;

[0104] Among them, the transient instantaneous pulse spike is generated based on the battery inductance.

[0105] Step S402: determining a battery characteristic fitting line based on performance parameters within a preset time period after the battery transient state ends;

[0106] The value of the preset time period is determined according to actual needs and is not limited in the present invention.

[0107] Performance parameters, such as battery voltage and battery current.

[0108] Step S403: replacing the transient pulse peak with the battery characteristic fitting line to obtain a target battery characteristic curve;

[0109] Step S404: Obtain the dynamic DC internal resistance of the battery based on the battery voltage and battery current corresponding to each moment in the target battery characteristic curve.

[0110] Among them, the expression of the dynamic DC internal resistance of the battery is as follows:

[0111]

[0112] Where z(t) represents the dynamic DC internal resistance of the battery, R0 represents the ohmic internal resistance of the battery, γ represents the relaxation time distribution spectrum, exp() represents the exponential function, t represents the time domain time, and τ represents the time constant.

[0113] To prove that the battery AC impedance spectrum obtained by the measurement method disclosed in the present invention is consistent with the battery AC impedance spectrum obtained by the measurement method of the traditional scheme, as shown in FIG. Figure 11 As shown, the Figure 4 The comparison chart of the battery AC impedance spectrum obtained by the battery equivalent circuit model in the above diagram and the battery AC impedance spectrum obtained by the traditional measurement method is shown in the figure. Figure 11 It can be seen that the battery AC impedance spectrum obtained by the measurement method disclosed in the present invention is highly consistent with the battery AC impedance spectrum obtained by the measurement method of the traditional solution.

[0114] Corresponding to the above method embodiment, the present invention also discloses a device for measuring the AC impedance spectrum of a battery.

[0115] See also Figure 12 , a schematic structural diagram of a device for measuring the AC impedance spectrum of a battery disclosed in an embodiment of the present invention, the device comprising:

[0116] An acquisition unit 501 is used to acquire a battery operating waveform;

[0117] In this embodiment, the battery operating waveform may include: a battery discharging waveform and / or a battery charging waveform in the time domain.

[0118] The battery discharge waveform includes: an initial discharge waveform and / or an end discharge waveform during the battery discharge process.

[0119] The battery charging waveform includes: an initial charging waveform and / or an end charging waveform during the battery charging process.

[0120] The battery operating waveform in this embodiment can be any one or a combination of the following: the initial discharge waveform and the final discharge waveform during the battery discharge process; and the initial charge waveform and the final charge waveform during the battery charge process. In other words, any one or any combination of the above four waveforms can be used as the battery operating waveform in this embodiment to obtain the final battery AC impedance spectrum.

[0121] A first determining unit 502 is configured to determine a battery inductance, a battery ohmic internal resistance, and a relaxation time distribution spectrum based on the battery operating waveform;

[0122] It should be noted that in the existing scheme, the relaxation time distribution spectrum can only be obtained by first obtaining the battery AC impedance spectrum through equipment such as an electrochemical workstation, and then inversely obtaining the relaxation time distribution spectrum. The relaxation time distribution spectrum in the present invention is directly determined based on the battery operating waveform. Therefore, compared with the relaxation time distribution spectrum obtained by inverse inference, it has higher accuracy, thereby improving the accuracy of the subsequent determination of the battery AC impedance spectrum to a certain extent.

[0123] a model building unit 503, configured to build a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum;

[0124] In this embodiment, the relaxation time distribution spectrum of the battery can be discretized into any number of series-connected resistor-capacitor pairs (RCpairs). That is, the relaxation time distribution spectrum includes multiple series-connected resistor-capacitor pairs, each of which is composed of a capacitor and a resistor connected in parallel.

[0125] All resistor and capacitor pairs, the battery inductance L0 and the battery ohmic internal resistance R0 together constitute a battery equivalent circuit model.

[0126] The second determining unit 504 is configured to determine the battery AC impedance spectrum according to the frequency response of the battery equivalent circuit model.

[0127] Specifically, the battery equivalent circuit model is used as a transfer function, and the response output of the transfer function at different frequencies is calculated, wherein the response output includes a real part and an imaginary part in a complex space. Finally, the real part and the imaginary part of the response output are formed into a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

[0128] In summary, the present invention discloses a device for measuring the AC impedance spectrum of a battery, which obtains a battery operating waveform, determines the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum based on the battery operating waveform, establishes a battery equivalent circuit model using at least one of the battery inductance, battery ohmic internal resistance, and relaxation time distribution spectrum, and determines the battery AC impedance spectrum based on the frequency response of the battery equivalent circuit model. It can be seen from this that the present invention does not require the addition of external AC excitation, and the battery AC impedance spectrum can be obtained by constructing a battery equivalent circuit model using the battery operating waveform. Not only is the hardware cost low and easy to implement, but the battery AC impedance spectrum has a fast measurement speed, and the battery equivalent circuit model can also be used to achieve online monitoring of the battery.

[0129] In addition, the relaxation time distribution spectrum in the present invention is directly determined based on the battery operating waveform, thereby improving the accuracy of the constructed battery equivalent circuit model and further improving the measurement accuracy of the battery AC impedance spectrum.

[0130] To further optimize the above embodiment, the first determining unit 502 may include:

[0131] a pulse peak determination subunit, configured to determine a transient instantaneous pulse peak based on the battery operating waveform;

[0132] The battery inductance determination subunit is configured to determine the corresponding battery inductance according to the transient instantaneous pulse peak.

[0133] To further optimize the above embodiment, the first determining unit 502 may further include:

[0134] a DC internal resistance determination subunit, configured to determine a battery dynamic DC internal resistance based on the battery operating waveform;

[0135] an ohmic internal resistance determination subunit, configured to directly obtain the battery ohmic internal resistance from the battery dynamic DC internal resistance;

[0136] The relaxation time distribution spectrum determination subunit is used to remove the component of the battery ohmic internal resistance from the battery dynamic DC internal resistance and perform a deconvolution operation on the remaining battery impedance to obtain the relaxation time distribution spectrum.

[0137] The DC internal resistance determination subunit can be specifically used for:

[0138] Determining a transient pulse peak based on the battery operating waveform, wherein the transient pulse peak is generated based on the battery inductance;

[0139] Determine a battery characteristic fitting line based on performance parameters within a preset time period after the battery transient state ends;

[0140] Replacing the transient pulse peak with the battery characteristic fitting line to obtain a target battery characteristic curve;

[0141] The dynamic DC internal resistance of the battery is obtained based on the battery voltage and battery current corresponding to each moment in the target battery characteristic curve.

[0142] To further optimize the above embodiment, the second determining unit 502 may be specifically configured to:

[0143] Using the battery equivalent circuit model as a transfer function, calculating a response output of the transfer function at different frequencies, wherein the response output includes a real part and an imaginary part in a complex space;

[0144] The real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

[0145] It should be noted that the specific working principles of the various components in the device embodiment can be found in the corresponding parts of the method embodiment and will not be repeated here.

[0146] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0147] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0148] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring battery AC impedance spectrum, characterized in that: include: Get the battery working waveform; Determining a battery inductance, a battery ohmic internal resistance, and a relaxation time distribution spectrum based on the battery operating waveform, including: determining a battery dynamic DC internal resistance based on the battery operating waveform; Establishing a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum; determining an AC impedance spectrum of the battery according to a frequency response of the battery equivalent circuit model; The process of determining the dynamic DC internal resistance of the battery based on the battery operating waveform includes: Determining a transient pulse peak based on the battery operating waveform, wherein the transient pulse peak is generated based on the battery inductance; Determine a battery characteristic fitting line based on performance parameters within a preset time period after the battery transient state ends; Replacing the transient pulse peak with the battery characteristic fitting line to obtain a target battery characteristic curve; The dynamic DC internal resistance of the battery is obtained based on the battery voltage and battery current corresponding to each moment in the target battery characteristic curve.

2. The measuring method according to claim 1, wherein The process of determining the battery inductance based on the battery operating waveform includes: Determining a transient pulse peak based on the battery operating waveform; The corresponding battery inductance is determined according to the transient instantaneous pulse peak.

3. The measuring method according to claim 1, wherein: The process of determining the battery ohmic internal resistance and the relaxation time distribution spectrum based on the battery operating waveform further includes: Directly obtaining the battery ohmic internal resistance from the battery dynamic DC internal resistance; The component of the battery ohmic internal resistance is removed from the battery dynamic DC internal resistance, and a deconvolution operation is performed on the remaining battery impedance to obtain the relaxation time distribution spectrum.

4. The measuring method according to claim 3, characterized in that The expression of the dynamic DC internal resistance of the battery is as follows: ； Where, represents the dynamic DC internal resistance of the battery, represents the battery's ohmic internal resistance, represents the relaxation time distribution spectrum, represents the exponential function, represents the time domain time, Represents the time constant.

5. The measuring method according to claim 1, wherein: The battery operating waveform includes: a battery discharge waveform and / or a battery charge waveform in the time domain; The battery discharge waveform includes: a start discharge waveform and / or a stop discharge waveform during the battery discharge process; The battery charging waveform includes: an initial charging waveform and / or an end charging waveform during the battery charging process.

6. The measuring method according to claim 1, characterized in that Determining the battery AC impedance spectrum according to the frequency response of the battery equivalent circuit model includes: Using the battery equivalent circuit model as a transfer function, calculating a response output of the transfer function at different frequencies, wherein the response output includes a real part and an imaginary part in a complex space; The real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

7. The measuring method according to claim 1, characterized in that The relaxation time distribution spectrum includes: a plurality of resistor-capacitor pairs connected in series, each of the resistor-capacitor pairs being composed of a capacitor and a resistor connected in parallel.

8. A device for measuring battery AC impedance spectrum, characterized in that: include: An acquisition unit, used for acquiring a battery operating waveform; a first determining unit, configured to determine a battery inductance, a battery ohmic internal resistance, and a relaxation time distribution spectrum based on the battery operating waveform; a model building unit, configured to build a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum; a second determining unit, configured to determine a battery AC impedance spectrum according to a frequency response of the battery equivalent circuit model; The first determining unit further includes: a DC internal resistance determination subunit, configured to determine a battery dynamic DC internal resistance based on the battery operating waveform; The DC internal resistance determination subunit is specifically used for: Determining a transient pulse peak based on the battery operating waveform, wherein the transient pulse peak is generated based on the battery inductance; Determine a battery characteristic fitting line based on performance parameters within a preset time period after the battery transient state ends; Replacing the transient pulse peak with the battery characteristic fitting line to obtain a target battery characteristic curve; The dynamic DC internal resistance of the battery is obtained based on the battery voltage and battery current corresponding to each moment in the target battery characteristic curve.

9. The measuring device according to claim 8, characterized in that The first determining unit includes: a pulse peak determination subunit, configured to determine a transient instantaneous pulse peak based on the battery operating waveform; The battery inductance determination subunit is configured to determine the corresponding battery inductance according to the transient instantaneous pulse peak.

10. The measuring device according to claim 8, characterized in that The first determining unit further includes: an ohmic internal resistance determination subunit, configured to directly obtain the battery ohmic internal resistance from the battery dynamic DC internal resistance; The relaxation time distribution spectrum determination subunit is used to remove the component of the battery ohmic internal resistance from the battery dynamic DC internal resistance and perform a deconvolution operation on the remaining battery impedance to obtain the relaxation time distribution spectrum.

11. The measuring device according to claim 8, characterized in that The second determining unit is specifically configured to: Using the battery equivalent circuit model as a transfer function, calculating a response output of the transfer function at different frequencies, wherein the response output includes a real part and an imaginary part in a complex space; The real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as the battery AC impedance spectrum.

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