KR20230168917A - Battery Parameter Estimation Method and Battery Parameter Acquisition Device - Google Patents

Abstract

The battery parameter estimation method of the present invention includes collecting measured values of applied current and terminal voltage in a discharge section during battery operation; Setting a voltage region for AC impedance calculation; And it may include deriving the AC impedance of the battery by applying the measured values of current and voltage collected in the voltage region to an equivalent circuit model.

Description

Battery parameter estimation method and battery parameter acquisition device {Battery Parameter Estimation Method and Battery Parameter Acquisition Device}

The present invention relates to a method of estimating battery parameters based on DC operation data considering AC impedance characteristics, and more specifically, to a method of deriving AC impedance parameters of a battery.

The aging of a battery is very different depending on various external environmental factors and the internal electrochemical mechanism of the battery. The cause of fire accidents in applications that use ESS and batteries as the main power source, which is rapidly occurring recently, is also unknown.

Various causes have been suggested, such as problems with the battery itself or malfunctions of the PCS and BMS, but in order to analyze these causes, it is essential to select an indicator that can indicate the internal chemical state of the battery based on various operation data.

In particular, recent technologies are being developed mainly for follow-up measures after an accident, such as reducing the operating area of the battery and blocking the chain reaction in the event of a fire in order to operate battery applications stably. This means the absence of technology that can infer the electrochemical state of the battery from the limited sensing information of the BMS and PCS supported by the application, and indicates the need for technology that can non-destructively derive the internal state of the battery from limited operational data. .

Electrochemical Impedance Spectroscopy (EIS) is a representative technique for non-destructively measuring the internal state of a battery. The EIS technique allows quantitative analysis of various physical phenomena, such as oxidation-reduction reactions that occur as lithium-ion batteries are repeatedly charged and discharged.

For the EIS technique, which is a method of analyzing and testing the condition of a battery as a result of changes in the AC impedance of the battery, the AC impedance needs to be measured during operation of the battery.

However, EIS is AC Impedance, and due to the nature of current applications that operate based on direct current, it is impossible to apply it with conventional technology. Therefore, considering the derivation characteristics of the AC impedance applied from high frequency to low frequency, it is necessary to derive these characteristics from the DC signal to diagnose abnormal conditions in the battery in advance rather than as an after-action measure, and to prevent fire and explosion accidents in advance.

In order to improve the problems of these conventional methods, there is a need to develop technology that can infer the internal chemical state of the battery from limited information. Technology is needed to consider the dynamic characteristics of the battery from DC-based sensing information and combine it with AC Impedance. In addition, based on the derived and monitored AC Impedance, the state of the battery in operation can be diagnosed and connected to the overall safety management system. You can.

Republic of Korea Publication No. 10-2020-0017367

The present invention seeks to provide a battery parameter estimation method and a battery parameter acquisition device that can non-destructively and accurately estimate the internal state of a battery through changes in electrochemical properties through parameter derivation considering AC impedance characteristics.

More specifically, the present invention considers the dynamic characteristics of the battery in DC-based sensing information and combines this with AC Impedance, and provides a method for diagnosing the state of the battery in operation based on the derived/monitored AC Impedance for use in the overall safety management system, etc. proposed for.

A battery parameter estimation method according to an aspect of the present invention includes collecting measured values of applied current and terminal voltage in a discharge section during battery operation; Setting a voltage region for AC impedance calculation; And it may include deriving the AC impedance of the battery by applying the measured values of current and voltage collected in the voltage region to an equivalent circuit model.

Here, setting the voltage area for calculating the AC impedance includes deriving the relationship between capacity and voltage; Deriving a relationship between voltage and incremental capacity; And it may include deriving a peak voltage, which is the voltage of the first peak point on the high voltage side, in the relationship between the voltage and the incremental capacity.

Here, deriving the AC impedance of the battery includes deriving a discharge start voltage and an initial drop point voltage due to discharge; and deriving a time constant point voltage in a peak voltage section derived from the initial drop point voltage and the peak voltage.

Here, deriving the AC impedance of the battery includes deriving electrolyte resistance from the discharge start voltage, the initial drop point voltage, and the applied current; and deriving a charge transfer resistance from the initial drop point voltage, the reference time constant point voltage in the voltage region, and the applied current.

Here, the step of deriving the AC impedance of the battery may further include deriving the Warburg impedance using a capacitance model and the deviation of the ideal voltage drop and the voltage drop when the diffusion phenomenon occurs.

A battery parameter acquisition device according to another aspect of the present invention includes a monitoring collection unit that collects measured applied current values and terminal voltage values in a discharge section during battery operation; a voltage range setting unit that sets a voltage range for calculating AC impedance from the collected measured applied current values, terminal voltage values, and battery discharge curve; and an AC impedance derivation unit that derives the AC impedance of the battery by applying the monitoring values in the voltage region to an equivalent circuit model.

Here, the voltage area setting unit derives the relationship between capacity and voltage, and derives the relationship between voltage and incremental capacity, so that the voltage at the first peak point on the high voltage side in the relationship between voltage and incremental capacity is the peak defining the voltage area. Voltage can be derived.

Here, it may further include a storage unit that stores the measured applied current values, terminal voltage values, and battery discharge curve information.

Here, the AC impedance deriving unit derives a discharge start voltage and an initial drop point voltage according to discharge from the collected measured applied current values and terminal voltage values, and uses the initial drop point voltage and the peak voltage to discharge the battery. By reflecting the curve, the time constant point voltage in the derived peak voltage section can be derived.

Here, the AC impedance deriving part includes an electrolyte resistance deriving part that derives electrolyte resistance from the discharge start voltage, the initial drop point voltage, and the applied current; and a charge transfer resistance deriving unit that derives charge transfer resistance from the initial drop point voltage, the reference time constant point voltage in the voltage region, and the applied current.

Here, the AC impedance derivation unit may further include a Warburg impedance derivation unit that derives the Warburg impedance using a capacitance model and the deviation of the ideal voltage drop and the voltage drop when a diffusion phenomenon occurs.

When the battery parameter estimation method and/or battery parameter acquisition device according to the spirit of the present invention of the above-described configuration is implemented, the internal state of the battery can be accurately and non-destructively determined through changes in electrochemical properties through parameter derivation considering AC impedance characteristics. There is an advantage to being able to estimate.

The battery parameter estimation method and/or battery parameter acquisition device of the present invention goes one step further from the prior art, which is limited to existing follow-up measures, and provides access to building a safety system that can diagnose the current battery status in operation in real time. There is an advantage.

Currently, in order to analyze the operation history data according to the aging of the battery, it is necessary to extract data and process it by mobilizing human resources in the application. However, in the battery parameter estimation method of the present invention, AC Impedance is itself the electrochemical effect of the battery. It can represent the state and also has the advantage of being able to reduce data storage capacity.

The battery parameter estimation method and/or battery parameter acquisition device of the present invention addresses problems within the battery management system of the application (cooling system) by introducing change patterns according to various cases (high temperature environment, vibration environment, etc.) as well as normal aging of the battery. problems, suspension problems) can be inferred, and it has the advantage of being expandable and applicable to a safety management system.

1 is a flowchart showing an embodiment of a battery parameter estimation method according to the spirit of the present invention.
Figures 2a and 2b are graphs showing electrochemical dynamics occurring during battery discharge as reflected in the equivalent circuit model.
Figure 3 is a conceptual diagram showing a method of deriving an incremental curve using the current applied to the battery and the voltage output.
Figure 4 is a graph illustrating defining the 'voltage area for AC impedance calculation' by peak voltage.
5A shows battery discharge curves according to the state of the battery.
FIG. 5B shows transient response equivalent circuit model graphs corresponding to each discharge curve in FIG. 5A.
FIG. 6 is a graph comparing the discharge curves of FIG. 5A and the simplified curves of FIG. 5B with identical V _tc (=V2) and τ values on a one-to-one basis.
Figure 7 is a block diagram showing an embodiment of a battery parameter acquisition device according to the spirit of the present invention.
Figures 8a to 8c are graphs showing the results of verifying impedance estimates extracted through a parameter estimation method according to the spirit of the present invention.

In describing the present invention, terms such as first and second may be used to describe various components, but the components may not be limited by the terms. Terms are intended only to distinguish one component from another. For example, a first component may be referred to as a second component, and similarly, the second component may be referred to as a first component without departing from the scope of the present invention.

When a component is mentioned as being connected or connected to another component, it can be understood that it may be directly connected to or connected to the other component, but other components may exist in between. .

The terms used herein are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions may include plural expressions, unless the context clearly indicates otherwise.

In this specification, terms such as include or have are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, including one or more other features or numbers, It can be understood that the existence or addition possibility of steps, operations, components, parts, or combinations thereof is not excluded in advance.

Additionally, the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

The terminal voltage that appears during charging and discharging of a lithium-ion battery generates non-linear dynamic characteristics through complex chemical processes such as instantaneous voltage drop, charge transfer between electrodes, and diffusion between electrolytes and electrodes and within electrodes. In a battery, ideally, the voltage drop due to Ohm's law should be maintained after the area where the voltage drop that occurs initially during discharge and the capacitance component due to charge transfer occurs, but the resistance component due to diffusion inside the battery's electrodes As a result, it can be seen that the voltage decreases more significantly than the voltage drop based on Ohm's law.

The present invention presents a parameter estimation technique based on DC operation data considering AC impedance characteristics. In the discharge section, a voltage region where electrochemical dynamics can be confirmed is selected, parameters are derived based on an equivalent circuit model, and changes in the internal chemical properties of the battery can be determined through each parameter. Conventional technology to estimate the internal state of the battery based on DC resistance parameters monitors the battery through electrical signals, but the present invention can more accurately estimate the internal state of the battery through changes in electrochemical characteristics by deriving parameters considering AC impedance characteristics. Provides technology.

Parameters considering the AC impedance characteristics derived from the present invention may be, for example, electrolyte resistance, charge transfer resistance, and Warburg impedance.

1 is a flowchart showing an embodiment of a battery parameter estimation method according to the spirit of the present invention.

The illustrated battery parameter estimation method includes monitoring the applied current and terminal voltage in the discharge section during battery operation (S120); Setting a voltage region for AC impedance calculation (S140); And it may include a step (S160) of deriving the AC impedance of the battery by applying the monitoring values in the voltage region to an equivalent circuit model.

The step S120 may be performed by collecting the measured applied current values and terminal voltage values and recording them in a storage unit, etc.

In step S140, the voltage range can be set through incremental capacity analysis (ICA) to confirm the electrochemical dynamic characteristics of the recorded information (values).

When deriving the IC curve to set the voltage region in step S140, the voltage region may be set differently depending on the size of the discharge current of the battery.

The 'voltage area for calculating AC impedance' set in step S140 is applied to the method of deriving impedance during discharge in step S160, and the peak voltage of the IC curve derived through ICA analysis is used to calculate 'AC impedance' After setting the 'voltage region for', the parameters corresponding to each device can be derived by using Randle's circuit, an electrochemical equivalent circuit model, for the voltage curve in that region. That is, in step S160, AC impedance parameters based on equivalent circuit model device characteristics are derived from the preset 'voltage area for calculating AC impedance'.

The present invention is an impedance estimation technology for real-time battery diagnosis, and additionally, in step S160, the impedance change tendency of the actual battery according to use can be compared to verify the reliability of the derived estimated impedance. To measure the impedance of an actual battery, the impedance can be derived through electrochemical impedance spectroscopy (EIS) and then compared with the estimated impedance.

Figures 2a and 2b are graphs showing electrochemical dynamic characteristics that occur during battery discharge as reflected in the equivalent circuit model.

In order to simulate the output voltage by each chemical process, the three characteristics of linear voltage reduction based on Ohm's law when internal chemical processes are ignored, voltage drop due to instantaneous current, and diffusion voltage through the capacitance component of the battery are measured. Modeling is possible using

Figure 3 is a conceptual diagram showing a method of deriving an incremental curve using the current applied to the battery and the voltage output in the step of setting the voltage region for calculating the AC impedance (S140).

As shown, the amount of current accumulated in a preset voltage section, that is, the amount of change in capacity, can be analyzed, and the three peak points appearing in the incremental curve are used as factors to estimate the internal state and deterioration state of the battery. possible. To derive the voltage drop that occurs at the start of discharging from the full charge voltage and the point where the voltage drop due to charge transfer ends, the voltage range can be set using the first peak voltage of the incremental capacity curve. During discharge, the voltage changes from high to low, so in the voltage-increment capacity graph shown, the first peak is the rightmost peak.

The step of setting the voltage region for calculating the AC impedance in FIG. 1 (S140) includes deriving the relationship between capacity and voltage (left and center graphs in FIG. 3); Deriving the relationship between voltage and incremental capacity (right graph in Figure 3); Deriving a peak voltage, which is the voltage at the first peak point on the high voltage side, from the relationship between the voltage and the incremental capacity; And it may include defining the 'voltage area for AC impedance calculation' as a discharge start voltage (or discharge initial drop point voltage) and peak voltage.

That is, an incremental capacity (IC) curve is derived from the collected applied current values and terminal voltage values, and the 'voltage area for AC impedance calculation' is defined as the first peak voltage from the derived IC curve.

Figure 4 is a graph illustrating the 'voltage area for AC impedance calculation' defined by the peak voltage.

As shown in Figure 4, the first peak voltage value of the incremental curve according to deterioration was used to set the region for deriving the impedance estimate (from discharge start voltage to peak voltage), and in the subsequent S160 step, current and voltage data of the region were collected. By using this, the electrolyte resistance (Rs) due to the instantaneous current and the impedance estimate of the charge transfer resistance (Rct) due to the initial current application can be derived.

In step S160 of FIG. 1, the current and voltage data of the 'voltage area for AC impedance calculation' are used to calculate electrolyte resistance (Rs) due to instantaneous current and charge transfer resistance (Rct) due to initial current application, and The bug impedance can be derived as AC impedance parameters.

AC impedance, as a modeling parameter, may include electrolyte resistance, charge transfer resistance, Warburg impedance, etc. Although there are other parameters, the above three parameters are important in modeling for battery diagnosis/analysis. Among them, the electrolyte resistance (Rs) can be estimated relatively easily, but it is not easy to obtain the charge transfer resistance (Rct) in an operating battery, even if it is an estimated value.

However, in the present invention, the charge transfer resistance (Rct) can be derived using the initial drop point voltage (V _drop ) and V(τ) at the τ point.

Additionally, in the present invention, the Warburg impedance can be obtained using the resistance-capacitance model of each simplified curve in FIG. 4b.

FIG. 5A shows battery discharge curves according to the state of the battery, and FIG. 5B shows transient response equivalent circuit model graphs corresponding to each discharge curve.

The graph in FIG. 5A may be obtained as discharge curves obtained by measuring the battery multiple times with different batteries of the same type by a manufacturer, etc., depending on the type of target battery. Among the multiple curves shown, the uppermost curve is for a battery in its initial state, and the lowermost curve is for a battery that has significantly deteriorated.

In the graph of FIG. 5A, V1 is the voltage in a dropped state immediately after the start of discharge and is the initial drop point voltage (V _drop ) of discharge. However, if precision is not required, it may be replaced with the discharge start voltage (V _ini ).

V3 is the peak voltage (V _peak ) and, as described above, can be determined as the voltage value at the first peak on the high voltage side of the voltage-incremental capacity curve shown on the far right of FIG. 3.

V2 is a value obtained from each curve in FIG. 5A after the values of V1 and V3 are determined, and becomes the peak voltage reference time constant point voltage (V _tc ).

Each voltage value in FIG. 5A can be obtained in step S160 of deriving the AC impedance of the battery in FIG. 1. That is, step S160 includes deriving a discharge start voltage (V _ini ) and an initial drop point voltage (V _drop ) according to discharge from the measured values collected in step S120; And among the discharge curves of FIG. 5A, using the discharge curve specified by the discharge start voltage (V _ini ) or the discharge initial drop point voltage (V _drop ), the initial drop point voltage (V _drop ) and the peak voltage It may include deriving a time constant point voltage (V _tc ) in the peak voltage section derived from (V _peak ).

Since impedance estimates are based on DC-based data, in step S160, they can be derived through an electrical equivalent circuit model-based parameter derivation method. For example, voltage values on a conceptual diagram such as Figure 5a are derived, and this is used to determine electrolyte resistance and Values for finding charge transfer resistance can be derived.

In other words, deriving the AC impedance of the battery (S160) includes deriving electrolyte resistance from the discharge start voltage, the initial drop point voltage, and the applied current; and deriving a charge transfer resistance from the initial drop point voltage, the reference time constant point voltage in the voltage region, and the applied current.

For example, in the step of deriving the electrolyte resistance, the electrolyte resistance (Rs_Est.) can be derived according to Equation 1 below.

For example, in the step of deriving the charge transfer resistance, the charge transfer resistance (Rct_Est.) can be derived according to Equation 2 below.

Additionally, in order to derive an impedance estimate corresponding to the diffusion resistance component that appears after the derived region, a capacitance model is used as shown in Figure 5b, and the deviation of the ideal voltage drop and the voltage drop when the diffusion phenomenon occurs is utilized to obtain the Warburg impedance estimate. can be derived.

The formula for the capacitance model used to derive the Warburg impedance estimate is as shown in Equation 3 below.

The transient response equation of Equation 3 can be expressed as a curve simplified by the points in FIG. 5b. Each dotted curve is for various values of τ. The τ value reflects the C component in the RC modeling of the battery, and can be obtained as the visual value at the point V _tc (=V2).

V ₀ is the convergence value of Vt, and the value of V ₀ can be obtained by applying the τ value known as the time value to t and substituting it into the equation summarized for V 0 in _Equation 3 above.

FIG. 6 is a graph comparing the discharge curves of FIG. 5A and the simplified curves of FIG. 5B with identical V _tc (=V2) and τ values on a one-to-one basis.

Derive the capacitance model voltage point corresponding to the time at the peak voltage point ( V _Peak ) derived from the graph shown, reflect this in the capacitance model, and use the voltage through this to determine the diffusion resistance component parameter (Warb._Est.), In other words, the Warburg impedance can be derived.

In other words, the step of deriving the AC impedance of the battery (S160) uses _a capacitance model to calculate _the Warberg A step of deriving impedance (Warb._Est.) may be further included.

For example, in the step of deriving the Warburg impedance (Warb._Est.), the Warburg impedance (Warb._Est.) can be derived according to Equation 4 below.

Figure 7 is a block diagram showing an embodiment of a battery parameter acquisition device according to the spirit of the present invention.

The illustrated battery parameter acquisition device includes a monitoring collection unit 110 that collects measured applied current values and terminal voltage values in a discharge section during battery operation; A voltage region setting unit 140 that sets a voltage region for AC impedance calculation from the collected applied current values, terminal voltage values, and battery discharge curves; and an AC impedance derivation unit 160 that derives the AC impedance of the battery by applying monitoring values in the voltage region to an equivalent circuit model.

The monitoring collection unit 110 measures the applied current and terminal voltage at a predetermined measurement interval time in the discharge section from the battery in operation and/or the PCS 200 for charging/discharging the battery, and shows the measured values. It can be collected by recording in the storage unit 120. The measurement time interval is preferably close enough to allow comparison with the battery discharge curve as shown in FIGS. 4 and 5.

The storage unit 120 may store battery discharge curve information as the measured applied current values, terminal voltage values, and unique characteristics of the battery. Depending on implementation, the battery discharge curve information may be stored as information that can define the curve as shown in FIG. 5A, or may be stored as only the voltage and time values at each point V1, V2, and V3 in FIG. 5A. there is.

The voltage area setting unit 140 derives the relationship between capacity and voltage, as shown in FIG. 3, and derives the relationship between voltage and incremental capacity, and determines the first peak point on the high voltage side in the relationship between voltage and incremental capacity. It is a voltage, and a peak voltage (V _peak ) defining the voltage region can be derived.

The AC impedance deriving unit 160 determines the discharge start voltage (V _ini ) and the initial drop point voltage (V _drop ) according to discharge are derived, and the initial drop point voltage (V _drop ) and the peak voltage (V _peak ) are reflected in the battery discharge curve, and the The time constant point voltage (V _tc ) can be derived.

The illustrated AC impedance deriving unit 160 utilizes the current and voltage data of the corresponding voltage region collected/recorded in the storage unit 120 to determine the electrolyte from the discharge start voltage and initial drop point voltage and the applied current. An electrolyte resistance deriving unit 162 that derives resistance (Rs_Est.); and a charge transfer resistance deriving unit 164 that derives a charge transfer resistance (Rct_Est.) from the initial drop point voltage and the reference time constant point voltage in the voltage region and the applied current. It may include a Warburg impedance deriving unit 166 that uses a capacitance model to derive the Warburg impedance (Warb._Est.) using the ideal voltage drop and the deviation of the voltage drop when the diffusion phenomenon occurs.

For example, the electrolyte resistance deriving unit 162 may perform derivation according to Equation 1, the charge transfer resistance deriving unit 164 may perform derivation according to Equation 2, and the Warburg The impedance deriving unit 166 may perform derivation according to Equations 3 and 4 above.

As shown, the electrolyte resistance (Rs_Est.), charge transfer resistance (Rct_Est.), and Warburg impedance (Warb._Est.) derived from the AC impedance deriving unit 160 are stored in the battery safety management system and/or BMS. It is provided and can be used to control/manage the battery.

Figures 8a to 8c are graphs showing the results of verifying the impedance estimate extracted through the parameter estimation method according to the spirit of the present invention.

As a result of verifying the impedance estimate value of the embodiment, there is an overall scale difference due to EIS measurement using minute current and voltage, but as shown in Figures 8a to 8c, the correlation coefficient of Rs is 09740, Rct is 09972, and ZW is 09240, which is the estimated impedance and It can be seen that the actual impedance has a high correlation.

Those skilled in the art to which the present invention pertains should understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features, and that the embodiments described above are illustrative in all respects and not restrictive. Just do it. The scope of the present invention is indicated by the claims described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. .

110: monitoring collection unit 120: storage unit
140: Voltage area setting unit 160: AC impedance deriving unit
162: electrolyte resistance deriving part 164: charge transfer resistance deriving part
166: Warburg impedance derivation unit

Claims (11)

Collecting measured values of applied current and terminal voltage in a discharge section during battery operation;
Setting a voltage region for AC impedance calculation; and
Deriving the AC impedance of the battery by applying the measured values of current and voltage collected in the voltage region to an equivalent circuit model.
A battery parameter estimation method including.
According to paragraph 1,
The step of setting the voltage area for calculating the AC impedance is,
Deriving the relationship between capacity and voltage;
Deriving a relationship between voltage and incremental capacity; and
Deriving a peak voltage, which is the voltage at the first peak point on the high voltage side, from the relationship between the voltage and the incremental capacity.
A battery parameter estimation method including.
According to paragraph 2,
The step of deriving the AC impedance of the battery is,
Deriving a discharge start voltage and an initial drop point voltage according to discharge; and
Deriving a time constant point voltage in a peak voltage section derived from the initial drop point voltage and the peak voltage
A battery parameter estimation method including.
According to paragraph 3,
The step of deriving the AC impedance of the battery is,
Deriving electrolyte resistance from the discharge start voltage and initial drop point voltage and the applied current; and
Deriving a charge transfer resistance from the initial drop point voltage and the reference time constant point voltage in the voltage region and the applied current.
A battery parameter estimation method including.
According to paragraph 4,
The step of deriving the AC impedance of the battery is,
A step of deriving the Warburg impedance using a capacitance model and using the ideal voltage drop and the deviation of the voltage drop when diffusion occurs.
A battery parameter estimation method further comprising:
a monitoring collection unit that collects measured applied current values and terminal voltage values in a discharge section during battery operation;
a voltage range setting unit that sets a voltage range for calculating AC impedance from the collected measured applied current values, terminal voltage values, and battery discharge curve; and
An AC impedance derivation unit that derives the AC impedance of the battery by applying the monitoring values in the voltage region to an equivalent circuit model.
A battery parameter acquisition device comprising a.
In paragraph 6
The voltage area setting unit,
Derive the relationship between capacity and voltage,
By deriving the relationship between voltage and incremental capacity,
A battery parameter acquisition device that derives a peak voltage that defines the voltage region and is the voltage at the first peak point on the high voltage side in the relationship between the voltage and incremental capacity.
According to clause 6,
A storage unit that stores the measured applied current values, terminal voltage values, and battery discharge curve information.
A battery parameter acquisition device further comprising:
In clause 7,
The AC impedance deriving part is,
Deriving a discharge start voltage and an initial drop point voltage due to discharge from the collected measured applied current values and terminal voltage values,
A battery parameter acquisition device that reflects the initial drop point voltage and the peak voltage in the battery discharge curve to derive a time constant point voltage in the derived peak voltage section.
According to clause 9,
The AC impedance deriving part is,
an electrolyte resistance deriving unit that derives electrolyte resistance from the discharge start voltage, the initial drop point voltage, and the applied current; and
A charge transfer resistance deriving unit that derives a charge transfer resistance from the initial drop point voltage and the reference time constant point voltage in the voltage region and the applied current.
A battery parameter acquisition device comprising a.
According to clause 10,
The AC impedance deriving part is,
Warburg impedance derivation unit that uses a capacitance model to derive Warburg impedance using the ideal voltage drop and the deviation of the voltage drop when diffusion occurs
A battery parameter acquisition device further comprising:

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