CN114660489A - Method and device for measuring alternating current impedance spectrum of battery - Google Patents
Method and device for measuring alternating current impedance spectrum of battery Download PDFInfo
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Abstract
The invention discloses a method and a device for measuring a battery alternating-current impedance spectrum, which are used for obtaining a battery working waveform, determining a battery inductance, a battery ohmic internal resistance and a relaxation time distribution spectrum according to the battery working waveform, establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum, and determining the battery alternating-current impedance spectrum according to the frequency response of the battery equivalent circuit model. Therefore, the battery alternating-current impedance spectrum can be obtained by constructing the battery equivalent circuit model by utilizing the working waveform of the battery without adding external alternating-current excitation, the hardware cost is low, the realization is easy, the measurement speed of the battery alternating-current impedance spectrum is high, and the online monitoring of the battery can be realized by the battery equivalent circuit model.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a method and a device for measuring an alternating current impedance spectrum of a battery.
Background
The battery ac Impedance spectrum is also called an Electrochemical Impedance Spectrum (EIS), and through the battery ac Impedance spectrum, not only can the dynamic process and mechanism thereof included in the battery system be analyzed, but also the battery abnormal condition can be identified, the battery consistency can be judged, and the SOC (State of Charge), the temperature and the like of the battery can be monitored on line.
The existing method for testing the alternating current impedance spectrum of the battery mainly comprises the following steps: when the battery is disturbed by an alternating current excitation signal of sinusoidal waveform voltage (current), the battery can generate a corresponding current (voltage) response signal, and the impedance of the battery electrode can be obtained according to the alternating current excitation signal and the response signal, so that an alternating current impedance spectrum generated by sine wave signals with a series of frequencies, namely the alternating current impedance spectrum of the battery, is formed.
However, the existing battery alternating current impedance spectrum testing method needs to add external alternating current excitation to obtain response, and has the disadvantages of expensive equipment, high cost, long measuring time and difficult online application.
Disclosure of Invention
In view of the above, the invention discloses a method and a device for measuring a battery alternating current impedance spectrum, so as to obtain the battery alternating current impedance spectrum by constructing a battery equivalent circuit model by using a battery working waveform without adding external alternating current excitation.
A method of measuring a battery ac impedance spectrum, comprising:
acquiring a battery working waveform;
determining battery inductance, ohmic internal resistance and relaxation time distribution spectrum based on the battery working waveform;
establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum;
and determining the alternating-current impedance spectrum of the battery according to the frequency response of the equivalent circuit model of the battery.
Optionally, the process of determining the battery inductance based on the battery operating waveform includes:
determining transient spike pulses based on the battery operating waveform;
and determining the corresponding battery inductance according to the transient pulse spike.
Optionally, the determining the ohmic internal resistance of the battery and the relaxation time distribution spectrum based on the battery operating waveform includes:
determining dynamic direct current internal resistance of the battery based on the battery working waveform;
directly obtaining the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery;
and removing the ohmic internal resistance component of the battery from the dynamic direct current internal resistance of the battery, and performing deconvolution operation on the residual battery impedance to obtain the relaxation time distribution spectrum.
Optionally, the process of determining the dynamic dc internal resistance of the battery based on the battery operating waveform includes:
determining a transient spike based on the battery operating waveform, wherein the transient spike is generated based on the battery inductance;
determining a battery characteristic fitting line according to performance parameters in a preset time period after the transient state of the battery is finished;
replacing the transient pulse spike by using the battery characteristic fitting line to obtain a target battery characteristic curve;
and obtaining the dynamic direct current internal resistance of the battery based on the battery voltage and the battery current corresponding to each moment in the target battery characteristic curve.
Optionally, the expression of the dynamic dc internal resistance of the battery is as follows:
wherein z (t) represents the dynamic DC internal resistance of the battery, R0Represents the ohmic internal resistance of the battery, gamma represents the relaxation time distribution spectrum, exp () represents an exponential function, t represents time domain time, and tau represents a time constant.
Optionally, the battery operating waveform includes: a time domain battery discharge waveform and/or a battery charge waveform;
the battery discharge waveform comprises: an initial discharge waveform and/or a terminal discharge waveform during discharge of the battery;
the battery charging waveform comprises: an initial charging waveform and/or a termination charging waveform during charging of the battery.
Optionally, the determining the ac impedance spectrum of the battery according to the frequency response of the battery equivalent circuit model includes:
taking the battery equivalent circuit model as a transfer function, and calculating response outputs of the transfer function at different frequencies, wherein the response outputs comprise a real part and an imaginary part in a complex space;
forming a Nyquist plot of the real and imaginary parts of the response output, and determining the Nyquist plot as the battery AC impedance spectrum.
Optionally, the relaxation time distribution spectrum includes: a plurality of resistor-capacitor pairs connected in series, each resistor-capacitor pair being formed by a capacitor and a resistor connected in parallel.
A battery ac impedance spectroscopy measurement apparatus comprising:
the acquisition unit is used for acquiring a battery working waveform;
the first determination unit is used for determining battery inductance, battery ohmic internal resistance and relaxation time distribution spectrum based on the battery working waveform;
the model establishing unit is used for establishing a battery equivalent circuit model by utilizing at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum;
and the second determination unit is used for determining the battery alternating-current impedance spectrum according to the frequency response of the battery equivalent circuit model.
Optionally, the first determining unit includes:
a pulse spike determination subunit for determining a transient pulse spike based on the battery operating waveform;
and the battery inductance determining subunit is used for determining the corresponding battery inductance according to the transient pulse spike.
Optionally, the first determining unit further includes:
the direct current internal resistance determining subunit is used for determining the dynamic direct current internal resistance of the battery based on the battery working waveform;
the ohmic internal resistance determining subunit is used for directly obtaining the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery;
and the relaxation time distribution spectrum determining subunit is used for removing the component of the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery and obtaining the relaxation time distribution spectrum by adopting deconvolution operation on the residual battery impedance.
Optionally, the dc internal resistance determining subunit is specifically configured to:
determining transient spike pulses based on the battery operating waveform, wherein the transient spike pulses are generated based on the battery inductance;
determining a battery characteristic fitting line according to performance parameters in a preset time period after the transient state of the battery is finished;
replacing the transient pulse spike by using the battery characteristic fitting line to obtain a target battery characteristic curve;
and obtaining the dynamic direct current internal resistance of the battery based on the battery voltage and the battery current corresponding to each moment in the target battery characteristic curve.
Optionally, the second determining unit is specifically configured to:
taking the battery equivalent circuit model as a transfer function, and calculating response outputs of the transfer function at different frequencies, wherein the response outputs comprise a real part and an imaginary part in a complex space;
forming a Nyquist plot of the real and imaginary parts of the response output, and determining the Nyquist plot as the battery AC impedance spectrum.
According to the technical scheme, the invention discloses a method and a device for measuring the alternating current impedance spectrum of the battery, which are used for obtaining the working waveform of the battery, determining the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum according to the working waveform of the battery, establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum, and determining the alternating current impedance spectrum of the battery according to the frequency response of the battery equivalent circuit model. Therefore, the battery alternating-current impedance spectrum can be obtained by constructing the battery equivalent circuit model by utilizing the working waveform of the battery without adding external alternating-current excitation, the hardware cost is low, the realization is easy, the measurement speed of the battery alternating-current impedance spectrum is high, and the online monitoring of the battery can be realized through the battery equivalent circuit model.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the disclosed drawings without creative efforts.
FIG. 1 is a flow chart of a method for measuring AC impedance spectra of a battery according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of an exemplary AC impedance spectroscopy test of a battery according to an embodiment of the present invention;
FIG. 3 is a graph of current and voltage waveforms during discharge of an exemplary battery disclosed in an embodiment of the present invention;
FIG. 4 is a schematic diagram of an equivalent circuit model of a battery according to an embodiment of the present invention;
FIG. 5 is a flowchart of a method for determining battery inductance based on a battery operating waveform according to an embodiment of the present invention;
FIG. 6 shows the voltage and current waveforms at the instant of discharging the battery according to the embodiment of the present invention;
fig. 7 is a flowchart of a method for determining ohmic internal resistance of a battery and a distribution spectrum of the relaxation time based on a battery operating waveform according to an embodiment of the present invention;
FIG. 8 is a waveform diagram of dynamic DC internal resistance of a battery in exponential coordinates according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a relaxation time distribution spectrum of a battery according to an embodiment of the disclosure;
FIG. 10 is a flowchart of a method for determining dynamic DC internal resistance of a battery based on a battery operating waveform according to an embodiment of the present invention;
FIG. 11 is a graph comparing an AC impedance spectrum of a battery obtained according to the present invention with an AC impedance spectrum of a battery obtained according to a conventional scheme, as disclosed in an embodiment of the present invention;
fig. 12 is a schematic structural diagram of a device for measuring an ac impedance spectrum of a battery according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a method and a device for measuring a battery alternating-current impedance spectrum, which are used for obtaining a battery working waveform, determining a battery inductance, a battery ohmic internal resistance and a relaxation time distribution spectrum according to the battery working waveform, establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum, and determining the battery alternating-current impedance spectrum according to the frequency response of the battery equivalent circuit model. Therefore, the battery alternating-current impedance spectrum can be obtained by constructing the battery equivalent circuit model by utilizing the working waveform of the battery without adding external alternating-current excitation, the hardware cost is low, the realization is easy, the measurement speed of the battery alternating-current impedance spectrum is high, and the online monitoring of the battery can be realized by the battery equivalent circuit model.
Referring to fig. 1, a flowchart of a method for measuring an ac impedance spectrum of a battery according to an embodiment of the present invention includes:
s101, acquiring a working waveform of a battery;
in this embodiment, the battery operating waveform may include: a battery discharge waveform and/or a battery charge waveform in the time domain.
Wherein the battery discharge waveform comprises: an initial discharge waveform and/or a final discharge waveform during discharge of the battery.
The battery charging waveform includes: an initial charging waveform and/or a termination charging waveform during charging of the battery.
The battery operating waveform in this embodiment may be: any one or combination of a plurality of waveforms of initial discharge, ending discharge and initial charge and ending charge in the process of charging the battery. That is, any one or any combination of the four waveforms may be used as the battery operating waveform in this embodiment to obtain the final battery ac impedance spectrum.
The battery working waveform can be obtained by using a typical battery alternating current impedance spectrum test circuit diagram shown in fig. 2, and the circuit comprises: battery LIB, switch S1And a resistance RbTaking the initial discharge waveform during the discharge of the battery as an example, by closing the switch S1Make the battery LIB to resist RbDischarging to obtain the initial discharge waveform of the battery LIB. In practical application, the voltage V at two ends of the battery in the discharging process of the battery LIB can be obtained through various testing meansbAnd a discharge current Ib. Referring to fig. 3 in detail, a typical Current-Voltage waveform diagram during battery discharge is shown, in fig. 3, the abscissa represents Time in units of S, the left ordinate represents Voltage across the battery Voltage in units of V, and the right ordinate represents Current in units of a.
Step S102, determining battery inductance, ohmic internal resistance and relaxation time distribution spectrum based on the battery working waveform;
it should be noted that, in the existing scheme, the relaxation time distribution spectrum can only be obtained by first obtaining the ac impedance spectrum of the battery through an electrochemical workstation and other devices, and then obtaining the relaxation time distribution spectrum by reverse-deriving, but the relaxation time distribution spectrum in the present invention is directly determined according to the working waveform of the battery, so that the present invention has higher accuracy compared with the relaxation time distribution spectrum obtained by reverse-deriving, and thus, the accuracy of subsequently determining the ac impedance spectrum of the battery is improved to a certain extent.
Step S103, establishing a battery equivalent circuit model by using at least one of battery inductance, battery ohmic internal resistance and relaxation time distribution spectrum;
in practical application, the battery equivalent circuit model can be constructed by using any one or a combination of a plurality of battery inductances, battery ohmic internal resistances and relaxation time distribution spectrums. When the battery equivalent circuit model is constructed by utilizing three parameters of battery inductance, battery ohmic internal resistance and relaxation time distribution spectrum, the accuracy of the battery equivalent circuit model is relatively highest.
In this embodiment, the relaxation time distribution spectrum of the battery may be discretized into any number of resistor-capacitor pairs (RC pairs) connected in series, that is, the relaxation time distribution spectrum includes a plurality of resistor-capacitor pairs connected in series, and each resistor-capacitor pair is formed by a capacitor and a resistor connected in parallel.
All resistor-capacitor pairs and battery inductor L0And ohmic internal resistance R of battery0And the two components jointly form a battery equivalent circuit model.
Referring to fig. 4, a schematic diagram of an equivalent circuit model of a battery is shown, wherein the equivalent circuit model of the battery includes: battery inductance L0Ohmic internal resistance R of the battery0And n resistor-capacitor pairs, battery inductance L0Ohmic internal resistance R of the battery0And n resistance-capacitance pairs are connected in series in sequence to form a battery equivalent circuit model, wherein the n resistance-capacitance pairs comprise: resistance R1And a capacitor C1A first resistor-capacitor pair formed by parallel connection, a resistor R2And a capacitor C2A second resistor-capacitor pair … … formed by parallel connection and a resistor RnAnd a capacitor CnAnd the n-th resistor-capacitor pair is formed by parallel connection.
And step S104, determining the alternating current impedance spectrum of the battery according to the frequency response of the equivalent circuit model of the battery.
Specifically, a battery equivalent circuit model is used as a transfer function, response output of the transfer function under different frequencies is calculated, wherein the response output comprises a real part and an imaginary part under a complex space, finally, the real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as a battery alternating-current impedance spectrum.
In summary, the invention discloses a method for measuring a battery alternating current impedance spectrum, which comprises the steps of obtaining a battery working waveform, determining a battery inductance, a battery ohmic internal resistance and a relaxation time distribution spectrum according to the battery working waveform, establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum, and determining the battery alternating current impedance spectrum according to the frequency response of the battery equivalent circuit model. Therefore, the battery alternating-current impedance spectrum can be obtained by constructing the battery equivalent circuit model by utilizing the working waveform of the battery without adding external alternating-current excitation, the hardware cost is low, the realization is easy, the measurement speed of the battery alternating-current impedance spectrum is high, and the online monitoring of the battery can be realized by the battery equivalent circuit model.
In addition, the relaxation time distribution spectrum is directly determined according to the working waveform of the battery, so that the accuracy of the constructed battery equivalent circuit model can be improved, and the measurement accuracy of the battery alternating-current impedance spectrum is improved.
In order to further optimize the above embodiment, referring to fig. 5, the present invention further discloses a method for determining the battery inductance based on the battery operating waveform, which includes:
step S201, determining transient pulse spikes based on a battery working waveform;
step S202, determining the corresponding battery inductance according to the transient pulse spike.
Taking the battery working waveform as the battery discharge waveform as an example, the process of determining the battery inductance is described as follows:
referring to fig. 6, in the embodiment of the present invention, the Voltage waveform and the Current at the instant of battery discharge are shown, the abscissa represents Time and unit S, the left ordinate represents Voltage across the battery, unit V, and the right ordinate represents Current and unit a, and with reference to fig. 2, at the switch S1The current changes at the moment after the battery is closed, the inductance in the battery induces current changes, and the battery enters an induction area at the moment, wherein the time of the induction area is tonI.e. tonIndicating switch S1And a transient time interval induced by the battery inductor after closing.
The present embodiment mainly infers the battery inductance L according to the voltage spike (i.e. transient pulse spike) induced by the battery inductance when the current changes0。
When the battery operating waveform is a battery charging waveform, the principle of determining the battery inductance is similar to that in fig. 6, and is not described herein again.
In order to further optimize the above embodiment, the present invention further discloses a process for determining the ohmic internal resistance of the battery and the relaxation time distribution spectrum based on the battery operating waveform, which is detailed in fig. 7, and the method includes the steps of:
step S301, determining dynamic direct current internal resistance of the battery based on the working waveform of the battery;
in practical applications, a battery characteristic fitting line may be used to replace a voltage spike caused by battery inductance (see fig. 6 in detail), and the battery voltage is divided by the battery current, so as to obtain the battery dynamic dc internal resistance, see the waveform diagram of the battery dynamic dc internal resistance in exponential coordinates shown in fig. 8 in detail.
Step S302, directly obtaining ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery;
and S303, removing the ohmic internal resistance component of the battery from the dynamic direct current internal resistance of the battery, and performing deconvolution operation on the residual battery impedance to obtain a relaxation time distribution spectrum.
Specifically, after the ohmic internal resistance of the battery is removed from the dynamic dc internal resistance of the battery in fig. 8, the relaxation time distribution spectrum γ of the battery can be obtained by performing a convolution operation, and the diagram of the relaxation time distribution spectrum of the battery shown in fig. 9 is shown in detail. In practical application, the deconvolution operation can be performed by fourier decomposition, wavelet analysis, or the like.
In summary, the relaxation time distribution spectrum of the battery can be obtained by only one deconvolution operation, and compared with the prior scheme that the voltage and the current need to be respectively subjected to spectrum analysis, and at least more than two times of similar operations of Fourier decomposition (or wavelet analysis and the like) are adopted, the relaxation time distribution spectrum determination method reduces the energy consumption during the relaxation time distribution spectrum determination.
In addition, the invention determines the relaxation time distribution spectrum in the process of acquiring the battery alternating-current impedance spectrum, which has extremely important significance for battery analysis and interpretation. Compared with the prior art that the battery alternating-current impedance spectrum can only be obtained through equipment such as an electrochemical workstation and the like, and then the relaxation time distribution spectrum is obtained through reverse estimation, the relaxation time distribution spectrum in the invention is directly determined according to the battery working waveform, so that the accuracy of the constructed battery equivalent circuit model can be improved, and the measurement accuracy of the battery alternating-current impedance spectrum is further improved.
In order to further optimize the above embodiment, referring to fig. 10, a flowchart of a method for determining a dynamic dc internal resistance of a battery based on a battery operating waveform disclosed in the embodiment of the present invention includes:
step S401, determining transient pulse spikes based on the working waveform of the battery;
wherein the transient spike is generated based on the battery inductance.
S402, determining a battery characteristic fitting line according to performance parameters in a preset time period after the transient state of the battery is finished;
the value of the preset time period is determined according to actual needs, and the invention is not limited herein.
Performance parameters such as battery voltage, battery current.
Step S403, replacing the transient pulse spike by using the battery characteristic fitting line to obtain a target battery characteristic curve;
and S404, obtaining the dynamic direct current internal resistance of the battery based on the battery voltage and the battery current corresponding to each moment in the target battery characteristic curve.
The expression of the dynamic direct current internal resistance of the battery is as follows:
wherein z (t) represents the dynamic DC internal resistance of the battery, R0Expressing the ohmic internal resistance of the battery, gamma expressing the distribution spectrum of the relaxation time, exp () expressing the exponential function, and t expressing the time domainIn between, τ represents a time constant.
In order to prove that the ac impedance spectrum of the battery obtained by the measurement method disclosed by the present invention is consistent with the ac impedance spectrum of the battery obtained by the measurement method of the conventional scheme, as shown in fig. 11, the comparison graph of the ac impedance spectrum of the battery obtained by the battery equivalent circuit model in fig. 4 and the ac impedance spectrum of the battery obtained by the measurement method of the conventional scheme is shown, and as can be seen from fig. 11, the ac impedance spectrum of the battery obtained by the measurement method disclosed by the present invention is highly consistent with the ac impedance spectrum of the battery obtained by the measurement method of the conventional scheme.
Corresponding to the embodiment of the method, the invention also discloses a device for measuring the alternating current impedance spectrum of the battery.
Referring to fig. 12, a schematic structural diagram of a device for measuring an ac impedance spectrum of a battery according to an embodiment of the present invention includes:
an obtaining unit 501, configured to obtain a battery operating waveform;
in this embodiment, the battery operating waveform may include: a battery discharge waveform and/or a battery charge waveform in the time domain.
Wherein the battery discharge waveform comprises: an initial discharge waveform and/or a final discharge waveform during discharge of the battery.
The battery charging waveform includes: an initial charging waveform and/or a termination charging waveform during charging of the battery.
The battery operating waveform in this embodiment may be: any one or combination of a plurality of waveforms of initial discharge, ending discharge and initial charge and ending charge in the process of charging the battery. That is, any one or any combination of the four waveforms may be used as the battery operating waveform in this embodiment to obtain the final battery ac impedance spectrum.
A first determining unit 502, configured to determine a battery inductance, a battery ohmic internal resistance, and a relaxation time distribution spectrum based on the battery operating waveform;
it should be noted that, in the existing scheme, the relaxation time distribution spectrum can only be obtained by first obtaining the ac impedance spectrum of the battery through an electrochemical workstation and other devices, and then obtaining the relaxation time distribution spectrum by reverse-deriving, but the relaxation time distribution spectrum in the present invention is directly determined according to the working waveform of the battery, so that the present invention has higher accuracy compared with the relaxation time distribution spectrum obtained by reverse-deriving, and thus, the accuracy of subsequently determining the ac impedance spectrum of the battery is improved to a certain extent.
A model establishing unit 503, configured to establish a battery equivalent circuit model using at least one of the battery inductance, the battery ohmic internal resistance, and the relaxation time distribution spectrum;
in this embodiment, the relaxation time distribution spectrum of the battery may be discretized into any number of resistor-capacitor pairs (RC pairs) connected in series, that is, the relaxation time distribution spectrum includes a plurality of resistor-capacitor pairs connected in series, and each resistor-capacitor pair is formed by a capacitor and a resistor connected in parallel.
All resistor-capacitor pairs and battery inductor L0And ohmic internal resistance R of battery0And the two components jointly form a battery equivalent circuit model.
A second determining unit 504, configured to determine a battery ac impedance spectrum according to the frequency response of the battery equivalent circuit model.
Specifically, a battery equivalent circuit model is used as a transfer function, response output of the transfer function under different frequencies is calculated, wherein the response output comprises a real part and an imaginary part under a complex space, finally, the real part and the imaginary part of the response output form a Nyquist diagram, and the Nyquist diagram is determined as a battery alternating-current impedance spectrum.
In summary, the invention discloses a device for measuring an alternating current impedance spectrum of a battery, which is used for obtaining a working waveform of the battery, determining a battery inductance, a battery ohmic internal resistance and a relaxation time distribution spectrum according to the working waveform of the battery, establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum, and determining the alternating current impedance spectrum of the battery according to the frequency response of the battery equivalent circuit model. Therefore, the battery alternating-current impedance spectrum can be obtained by constructing the battery equivalent circuit model by utilizing the working waveform of the battery without adding external alternating-current excitation, the hardware cost is low, the realization is easy, the measurement speed of the battery alternating-current impedance spectrum is high, and the online monitoring of the battery can be realized by the battery equivalent circuit model.
In addition, the relaxation time distribution spectrum is directly determined according to the working waveform of the battery, so that the accuracy of the constructed battery equivalent circuit model can be improved, and the measurement accuracy of the battery alternating-current impedance spectrum is improved.
To further optimize the above embodiment, the first determining unit 502 may include:
a pulse spike determination subunit for determining a transient pulse spike based on the battery operating waveform;
and the battery inductance determining subunit is used for determining the corresponding battery inductance according to the transient pulse spike.
To further optimize the above embodiment, the first determining unit 502 may further include:
the direct current internal resistance determining subunit is used for determining the dynamic direct current internal resistance of the battery based on the battery working waveform;
the ohmic internal resistance determining subunit is used for directly obtaining the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery;
and the relaxation time distribution spectrum determining subunit is used for removing the component of the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery and obtaining the relaxation time distribution spectrum by adopting deconvolution operation on the residual battery impedance.
The dc internal resistance determining subunit may be specifically configured to:
determining transient spike pulses based on the battery operating waveform, wherein the transient spike pulses are generated based on the battery inductance;
determining a battery characteristic fitting line according to performance parameters in a preset time period after the transient state of the battery is finished;
replacing the transient pulse spike by using the battery characteristic fitting line to obtain a target battery characteristic curve;
and obtaining the dynamic direct current internal resistance of the battery based on the battery voltage and the battery current corresponding to each moment in the target battery characteristic curve.
To further optimize the above embodiment, the second determining unit 502 may specifically be configured to:
taking the battery equivalent circuit model as a transfer function, and calculating response outputs of the transfer function at different frequencies, wherein the response outputs comprise a real part and an imaginary part under a complex space;
forming a Nyquist plot of the real and imaginary parts of the response output, and determining the Nyquist plot as the battery AC impedance spectrum.
It should be noted that specific working principles of each component in the device embodiment may refer to corresponding parts in the method embodiment, and are not described herein again.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (13)
1. A method for measuring battery AC impedance spectrum is characterized by comprising the following steps:
acquiring a battery working waveform;
determining battery inductance, ohmic internal resistance and relaxation time distribution spectrum based on the battery working waveform;
establishing a battery equivalent circuit model by using at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum;
and determining the alternating-current impedance spectrum of the battery according to the frequency response of the equivalent circuit model of the battery.
2. The measurement method of claim 1, wherein determining the battery inductance based on the battery operating waveform comprises:
determining transient spike pulses based on the battery operating waveform;
and determining the corresponding battery inductance according to the transient pulse spike.
3. The measurement method of claim 1, wherein determining the ohmic internal resistance of the battery and the relaxation time distribution spectrum based on the battery operating waveform comprises:
determining dynamic direct current internal resistance of the battery based on the battery working waveform;
directly obtaining the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery;
and removing the ohmic internal resistance component of the battery from the dynamic direct current internal resistance of the battery, and performing deconvolution operation on the residual battery impedance to obtain the relaxation time distribution spectrum.
4. The method of claim 3, wherein the determining the dynamic DC internal resistance of the battery based on the battery operating waveform comprises:
determining transient spike pulses based on the battery operating waveform, wherein the transient spike pulses are generated based on the battery inductance;
determining a battery characteristic fitting line according to performance parameters in a preset time period after the transient state of the battery is finished;
replacing the transient pulse spike by using the battery characteristic fitting line to obtain a target battery characteristic curve;
and obtaining the dynamic direct current internal resistance of the battery based on the battery voltage and the battery current corresponding to each moment in the target battery characteristic curve.
5. The method of claim 3, wherein the expression of the dynamic DC internal resistance of the battery is as follows:
wherein z (t) represents the dynamic DC internal resistance of the battery, R0Represents the ohmic internal resistance of the battery, gamma represents the relaxation time distribution spectrum, exp () represents an exponential function, t represents time domain time, and tau represents a time constant.
6. The measurement method of claim 1, wherein the battery operating waveform comprises: a battery discharge waveform and/or a battery charge waveform in the time domain;
the battery discharge waveform comprises: an initial discharge waveform and/or a final discharge waveform during discharge of the battery;
the battery charging waveform includes: an initial charging waveform and/or a termination charging waveform during charging of the battery.
7. The measurement method according to claim 1, wherein the determining a battery ac impedance spectrum from the frequency response of the battery equivalent circuit model comprises:
taking the battery equivalent circuit model as a transfer function, and calculating response outputs of the transfer function at different frequencies, wherein the response outputs comprise a real part and an imaginary part in a complex space;
forming a Nyquist plot of the real and imaginary parts of the response output, and determining the Nyquist plot as the battery AC impedance spectrum.
8. The measurement method according to claim 1, wherein the relaxation time distribution spectrum includes: a plurality of resistor-capacitor pairs connected in series, each resistor-capacitor pair being formed by a capacitor and a resistor connected in parallel.
9. A device for measuring ac impedance spectra of a battery, comprising:
the acquisition unit is used for acquiring a battery working waveform;
the first determination unit is used for determining battery inductance, battery ohmic internal resistance and relaxation time distribution spectrum based on the battery working waveform;
the model establishing unit is used for establishing a battery equivalent circuit model by utilizing at least one of the battery inductance, the battery ohmic internal resistance and the relaxation time distribution spectrum;
and the second determination unit is used for determining the battery alternating-current impedance spectrum according to the frequency response of the battery equivalent circuit model.
10. The measurement device according to claim 9, wherein the first determination unit includes:
a pulse spike determination subunit for determining a transient pulse spike based on the battery operating waveform;
and the battery inductance determining subunit is used for determining the corresponding battery inductance according to the transient pulse spike.
11. The measurement device according to claim 9, wherein the first determination unit further includes:
the direct current internal resistance determining subunit is used for determining the dynamic direct current internal resistance of the battery based on the battery working waveform;
the ohmic internal resistance determining subunit is used for directly obtaining the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery;
and the relaxation time distribution spectrum determining subunit is used for removing the component of the ohmic internal resistance of the battery from the dynamic direct current internal resistance of the battery and obtaining the relaxation time distribution spectrum by adopting deconvolution operation on the residual battery impedance.
12. The measurement device according to claim 11, wherein the direct current internal resistance determining subunit is specifically configured to:
determining transient spike pulses based on the battery operating waveform, wherein the transient spike pulses are generated based on the battery inductance;
determining a battery characteristic fitting line according to performance parameters in a preset time period after the transient state of the battery is finished;
replacing the transient pulse spike by using the battery characteristic fitting line to obtain a target battery characteristic curve;
and obtaining the dynamic direct current internal resistance of the battery based on the battery voltage and the battery current corresponding to each moment in the target battery characteristic curve.
13. The measurement device according to claim 9, wherein the second determination unit is specifically configured to:
taking the battery equivalent circuit model as a transfer function, and calculating response outputs of the transfer function at different frequencies, wherein the response outputs comprise a real part and an imaginary part in a complex space;
forming a Nyquist plot of the real and imaginary parts of the response output, and determining the Nyquist plot as the battery AC impedance spectrum.
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| CN202210317370.2A CN114660489A (en) | 2022-03-29 | 2022-03-29 | Method and device for measuring alternating current impedance spectrum of battery |
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| CN202210317370.2A CN114660489A (en) | 2022-03-29 | 2022-03-29 | Method and device for measuring alternating current impedance spectrum of battery |
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