WO2023167394A1

WO2023167394A1 - Method for estimating state of battery

Info

Publication number: WO2023167394A1
Application number: PCT/KR2022/019495
Authority: WO
Inventors: 홍영진; 이영재; 주유진; 최성호; 명석한; 김두리; 정지현; 김태훈
Original assignee: 주식회사 민테크
Priority date: 2022-03-03
Filing date: 2022-12-02
Publication date: 2023-09-07
Also published as: KR20230130238A

Abstract

Disclosed are a method for estimating the state of a battery and an apparatus for estimating the state of a battery. The present invention comprises the steps of: determining the SOC of the battery; applying a charging current or a discharging current to the battery on the basis of the result of determining the SOC; applying at least one charging pulse current and at least one discharging pulse current to the battery; measuring the voltage Vc changed when the charging pulse current is applied and measuring the voltage Vd changed when the discharging pulse current is applied; and estimating the average value of Vc and Vd as the Nernst OCV of the battery, wherein the Nernst OCV is estimated, and the SOC is calculated so that the capacity life (SOH) of the battery can be calculated.

Description

How to estimate battery health

The present invention relates to a method and apparatus capable of estimating the state of a battery.

Batteries are used as power sources for mobile devices and electric vehicles, and demand for them is explosively increasing with the recent popularization of electric vehicles. In particular, unlike small batteries with low unit prices, demand for methods for recycling/reusing batteries or stably using batteries for a long period of time is increasing as demand for medium and large-sized batteries with high unit prices increases.

Accurately diagnosing the state of the battery is important in order to re-use the battery or to use the battery stably and for a long time. If the state of the battery can be accurately diagnosed, the direction can be set to efficiently reuse the battery, and the lifespan of the battery can be improved by preventing overcharging or overdischarging during charging and discharging of the battery. .

In order to estimate the state of the battery, open circuit voltage (OCV) or state of charge (SOC) that can represent thermodynamic information of the battery is used. OCV is the voltage of the battery measured in a state in which the circuit is open, and means the voltage of the battery measured in a state in which the current applied to the battery is zero. Here, the OCV of the battery may simply mean the voltage measured in the open circuit state or the voltage measured in the electrochemically equilibrated state after a long time in the circuit open state. The voltage measured in the state can be defined as Nernst OCV (Nernst OCV). Here, since the Nernst OCV is a voltage measured in an electrochemical equilibrium state, it can be considered to provide information about the thermodynamic state of the battery.

Various methods of measuring Nernst OCV and SOC of a battery have been proposed to accurately estimate the state of the battery. In general, a method of estimating the Nernst OCV of a battery is a method of estimating using a voltage value that converges when the battery is stabilized for a certain period of time (eg, 2 hours or more) in a state where no external electrical stimulation is applied. However, since the internal state of the battery must reach electrochemical equilibrium in order to estimate the Nernst OCV in this way, there is a disadvantage in that a lot of cost and time are incurred.

Accordingly, there is a demand for development of a method and apparatus capable of accurately and quickly estimating the Nernst OCV and accurately estimating the battery state based thereon.

The problem to be solved by the present invention is to provide a method for quickly and accurately estimating the Nernst OCV of a battery within minutes.

An object to be solved by the present invention is to provide a method for calculating SOC of a battery based on the estimated Nernst OCV and calculating State of Health (SOH) using the calculated SOC.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned above can be understood by the following description and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations indicated in the claims.

A battery state estimation method according to an aspect of the present invention

(S100) determining the SOC of the battery;

(S200) based on the SOC determination result, applying a charging current or a discharging current to the battery;

(S300) applying at least one charging pulse current and at least one discharging pulse current to the battery;

(S400) measuring the changed voltage V _c when the charging pulse current is applied, and measuring the changed voltage V _d when the discharge pulse current is applied;

(S500) estimating the average value of V _c and V _d as the Nernst OCV of the battery; It is characterized in that it includes.

According to the present invention, when the SOC of the battery determined in step (S100) is less than or equal to the reference SOC, a charging current is applied in step (S200), and if the SOC of the battery determined in step (S100) is greater than or equal to the reference SOC, (S200 ) step, the discharge current can be applied. The reference SOC may be at a point between 20% and 80%.

According to the present invention, at least one charge pulse current and at least one discharge pulse current applied in step (S300) may be applied alternately.

According to the present invention, the pulse current applied in step (S300) may first be applied with a pulse current having an opposite sign to the current applied in step (S200).

According to the present invention, the total charge capacity (Ah) by at least one charging pulse current applied in step (S300) and the total discharge capacity (Ah) by at least one discharge pulse current may be equal to each other.

According to the present invention, the size of the pulse current applied in step (S300) is 0.1 C-rate to 10.0 C-rate, and the time for applying the pulse current may be 0.1 second to 500 seconds.

According to the present invention, at least one pause step may be inserted between the step of applying at least one charge pulse current and at least one discharge pulse current in step S300.

According to the present invention, the pause step inserted between the applying of the at least one charge pulse current and the at least one discharge pulse current may be maintained for 0.1 second to 500 seconds, or 0.1 second to 120 seconds.

According to the present invention, the total time (τ _A ) during which at least one charge pulse current is applied and the total time (τ _B ) during which at least one discharge pulse is applied may be equal to each other in step S300 .

According to the present invention, the rest step inserted between the applying of the at least one charge pulse current and the at least one discharge pulse current may be maintained for 0.1·τ _A to 10·τ _A.

According to the present invention, the average of step (S500) may be calculated by any one or combination of arithmetic average, geometric average, and harmonic average.

According to the present invention, the step of calculating the SOC of the battery using the estimated Nernst OCV (S600) may further be included, and the step of calculating the SOC refers to a reference table corresponding to the estimated Nernst OCV. You can calculate the SOC using a specific formula.

According to the present invention, the above-described SOC calculation of the battery may be performed multiple times in different charging states of the battery.

According to the present invention, a step of calculating a capacity lifetime (SOH) based on the calculated SOC of multiple times may be further included (S700).

According to the present invention, the SOC of the battery is determined, the charging current or the discharging current is applied based on the SOC determination result, at least one charging pulse current and at least one discharging pulse current are applied to the battery, and the charging pulse current is applied. A battery state including a processor that measures the voltage V _c changed when current is applied, measures the voltage V _d changed when discharge pulse current is applied, and estimates the average value of the V _c and V _d as Nernst OCV. An estimation device can be provided.

The solution to the above problems does not enumerate all the features of the present invention. Various features of the present invention and the advantages and effects thereof will be understood in more detail with reference to the following specific examples.

According to the present invention, it is possible to provide a method for quickly and accurately estimating the Nernst OCV of a battery.

According to the present invention, a method for calculating the SOC of a battery changed during partial charge and discharge using the Nernst OCV value estimated before and after partial charge and discharge and calculating the capacity life (SOH) of the battery using the calculated SOC change amount is provided. can

In addition to the above effects, specific effects of the present invention will be described together while explaining specific details for carrying out the present invention.

1 is a flowchart illustrating a method for estimating a battery state according to an embodiment of the present invention.

FIG. 2 shows that the application profiles of the charging pulse current and the discharging pulse current according to an embodiment of the present invention and the total charge/discharge capacity by each pulse current are equal to each other.

3 is a flowchart of application of charging current and discharging current according to an embodiment of the present invention.

4 shows an example of a method for estimating a battery state according to an embodiment of the present invention, and is a graph showing a change in voltage when current is applied.

5 is a table showing that Nernst OCV is estimated by the method of the present invention in a module or pack type battery and an error rate with an actual Nernst OCV is calculated.

6 shows an example of a battery state estimation method according to an embodiment of the present invention, and is a graph showing estimating Nernst OCV and SOC before and after partial discharge at different time points.

Hereinafter, the principles of preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings and description. However, the drawings shown below and the description below relate to preferred implementation methods among various methods for effectively explaining the features of the present invention, and the present invention is not limited to only the drawings and description below.

Meanwhile, terms such as first or second may be used to describe various components, but these terms should be interpreted only for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element.

Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but one or more other features or numbers, It should be understood that the presence or addition of steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this specification, it should not be interpreted in an ideal or excessively formal meaning. don't

1 is a flowchart illustrating a method for estimating a state of a battery according to an embodiment of the present invention.

The battery in the present invention includes a capacitor or a secondary battery that stores power by charging, and a device employing the battery can receive power from the battery as a load. Here, the battery includes a battery pack composed of a plurality of battery modules, at least one battery module in the battery pack, a battery module composed of a plurality of battery cells, at least one battery cell in the battery module, a representative module representing a plurality of battery modules, and a plurality of battery modules. It may include at least one of representative cells representing battery cells of , and hereinafter, a battery may be interpreted as referring to these examples.

First, referring to FIG. 1 , a method for estimating a battery state according to the present invention includes determining a state of charge (SOC) of a battery (S100).

Here, SOC is a parameter indicating the state of charge of the battery. Since SOC indicates how much energy is stored in the battery, the amount can be expressed as 0 to 100% using a percentage (%) unit. For example, 0% may mean a fully discharged state and 100% may mean a fully charged state, and this expression method may be modified and defined in various ways according to design intentions or embodiments.

Specifically, the battery state estimation method according to the present invention may include determining the SOC of a battery in a rest state. The dormant state means a state in which the battery is not being charged or discharged, and the battery may be a battery stored for a long time after being collected for reuse.

Meanwhile, the SOC determination of the battery through the step (S100) is a step for roughly estimating the initial state of the battery before diagnosing the state of the battery, and is distinguished from the SOC calculation in the step (S600) described later. Unlike the step (S600) of calculating the exact SOC of the battery, the SOC determination of the step (S100) has the purpose of determining the current sign of the subsequent current application step (S200).

The SOC measurement of the battery in step (S100) according to an embodiment of the present invention may use a known method such as a voltage measurement method or a resistance measurement method, and is not limited to a specific SOC measurement method.

The battery state estimation method according to the present invention may further include a visual inspection step of determining whether at least one state of damage, swelling, or discoloration of the battery is within a predetermined effective range prior to the step of determining the SOC of the battery (S100). can The external inspection for sensing at least one of damage, swelling, and discoloration of the battery may be performed through a camera, optical sensor, or electrochemical impedance spectroscopy, and if it is determined that the inspection result is within a preset effective range, the next step may be performed. there is.

Referring back to FIG. 1 , the battery state estimation method of the present invention may include applying a charging current or a discharging current to the battery (S200).

Here, the magnitude of the charge current or discharge current applied to the battery may be 0.1 C-rate to 1 C-rate, preferably 0.2 C-rate to 0.5 C-rate, and the charge current or discharge current is the nominal capacity of the battery. It may be applied within the range of 0 to 40% of (nominal capacity) and preferably 0 to 20%.

Meanwhile, the battery state estimation method of the present invention may further include a battery rest step (S201) after the step (S200). Here, the resting step can be maintained for 1 to 60 minutes, preferably 2 to 30 minutes. A short amount of time is enough.

The battery is charged or discharged in advance through the steps (S200) and (S201), and the dormant phase is maintained for a predetermined time, thereby activating the battery and making the internal state of the battery uniform before the Nernst OCV estimation step.

In the present invention, the process of pre-charging/discharging the battery before the Nernst OCV estimation step to maintain the idle step is defined as pre-conditioning. Pre-conditioning can be performed with only a low C-rate, which has the advantage of high versatility.

Meanwhile, the application of the charging current or the discharging current in step S200 is determined by determining the battery SOC in step S100. Here, when the determined SOC is determined to be less than or equal to the reference SOC, the charging current may be applied first, and when determined to be greater than or equal to the reference SOC, the discharge current may be applied first.

For example, if the standard SOC is designed to be 50%, and the SOC of the battery determined in step (S100) is lower than the SOC of 50%, the battery can be charged by applying a charging current, and the SOC of the battery to be measured is the SOC If it is higher than 50%, the battery can be discharged by applying a discharge current.

According to an embodiment of the present invention, the reference SOC may be a point in the range of 20% to 80%, preferably 30% to 70%.

The battery state estimation method of the present invention may further include measuring electrochemical impedance spectroscopy (EIS) after the step (S201) (S202). In this case, the step of measuring the electrochemical impedance may be performed under a frequency condition between 4 kHz and 0.1 Hz. The electrochemical impedance measurement step (S202) is preferably performed after the rest time of (S201), but may be performed before the step (S201), and is not limited to a specific order. Here, the step of measuring the electrochemical impedance is a step for measuring the resistance in the battery and can be used as an index to increase the accuracy of Nernst OCV estimation.

Referring back to FIG. 1 , the battery state estimation method of the present invention includes applying at least one charge pulse current and at least one discharge pulse current to the battery (S300). Here, the charging pulse current and the discharging pulse current are applied in a manner in which the charging pulse current and the discharging pulse current are applied by applying the current profile to the battery. The current profile refers to a policy for determining a method or command for applying current/voltage to a battery, and may be designed to include at least one charging pulse and at least one discharging pulse.

At this time, setting the order and frequency of application of the charge pulse current and the discharge pulse current may be modified and applied according to the design intention. An embodiment of the current profile including the application of the charging pulse current and the application of the discharging pulse current is shown in FIG. 2 . FIG. 2 illustrates an embodiment of a current profile including one charge pulse current and one discharge pulse current, and a rest time inserted between the application of the charge pulse current and the discharge pulse current.

According to one embodiment of the present invention, the current profile may be designed in a form in which at least one charge pulse current and at least one discharge pulse current are alternately included. For example, if the charging pulse current is applied to the battery first, the discharging pulse current may be applied next, and if the discharging pulse current is applied first, the charging pulse current may be applied next.

The order of applying the charge pulse current or discharge pulse current in step (S300) is determined by the type (sign of current) of the current applied in step (S200), and the pulse current opposite to the sign of the current applied in step (S200) is may be authorized. For example, if the current applied in step (S200) is the charging current, the discharge pulse current may be applied first, and if the current applied in step (S200) is the discharge current, the charging pulse current is applied first. can be designed to be

In the battery state estimation method according to an embodiment of the present invention, the applied charge pulse current and discharge pulse current may range from 0.1 C-rate to 10.0 C-rate, preferably from 0.1 C-rate to 3.0 C-rate. can In the battery state estimation method according to an embodiment of the present invention, the charge pulse current and the discharge pulse current may be applied for 0.1 seconds to 500 seconds, preferably 0.1 seconds to 60 seconds, and more preferably 0.1 seconds to 10 seconds. there is.

Meanwhile, in step S300, the total charge capacity (Ah) by at least one charging pulse current applied to the battery and the total discharge capacity (Ah) by at least one discharge pulse current applied to the battery may be the same (FIG. 2). By equalizing the total charge capacity (Ah) by the charge pulse current and the total discharge capacity (Ah) by the discharge pulse current, the non-faradaic current inside the battery is canceled, and the faradaic current Only reactions can be detected.

According to an embodiment of the present invention, the current profile applied in step S300 may be designed in a form in which a rest step is inserted between at least one charge pulse current and at least one discharge pulse current. By inserting the pause step, the internal state of the battery according to the application of the corresponding pulse current can be stabilized, and a more accurate voltage change value can be measured in measuring the voltage change according to the subsequent application of the pulse current. The pause step may be included one or more times, may be modified and applied according to design intent, and is not particularly limited (see FIG. 2).

In the battery state estimation method of the present invention, the pause step inserted between the at least one charging pulse current and the at least one discharging pulse current may be maintained for 0.1 to 500 seconds, preferably 0.1 to 120 seconds.

Meanwhile, according to another embodiment of the present invention, the total time τ _A for which at least one charging pulse current is applied and the total time (τ _B ) for which at least one discharge pulse is applied may be equal to each other. At this time, the pause step inserted between the at least one charge pulse current and the at least one discharge pulse current may be set to be maintained for a time ranging from 0.1·τ _A to 10·τ _A.

Referring back to FIG. 1 , the method for estimating a battery state according to the present invention includes measuring a change in voltage of a battery that appears when a charge pulse current and a discharge pulse current are applied to the battery (S400). When the charging pulse current or the discharging pulse current according to the above-described current profile is applied to the battery, the voltage of the battery is changed, and the changed voltage according to the application of the pulse current is measured. The voltage at this time is a closed circuit voltage (CCV) because it is measured in a state where current is applied.

For example, a voltage measured when a charging pulse current is applied may be defined as a charging voltage (V _c ), and a voltage measured when a discharge pulse is applied may be defined as a discharge voltage (V _d ). 4 illustrates a voltage change pattern of a battery appearing when a pulse current is applied according to an embodiment of the present invention. According to the example of FIG. 4 , voltage V _c due to application of a charging pulse may be 3.558 V, and voltage V _d due to application of a discharging pulse may be measured as 3.494 V.

Referring back to FIG. 1 , the battery state estimation method according to the present invention includes calculating an average value based on the V _c and V _d values and estimating the average value as the Nernst OCV of the battery (S500). . In this case, the average of V _c and V _d may be any one of an arithmetic average, a geometric average, and a harmonic average.

According to the example of FIG. 4 , V _c is 3.558 V, V _d is 3.494 V, and (3.558 V+3.494 V)/2 = 3.526 V is calculated using the arithmetic mean, which is one embodiment. In the example of FIG. 4 , 3.526V can be estimated as the Nernst OCV of the battery.

In general, when a current is applied to a battery, an electrochemical reaction occurs, and an energy state (voltage) of the battery may change due to the electrochemical reaction. At some point, when the applied current becomes 0, the voltage of the battery converges to a certain voltage. Here, Nernst OCV of the battery may be estimated based on a value at which the voltage of the battery converges. The Nernst OCV stabilization time is the time required to estimate the Nernst OCV of the battery, and refers to the time required for the voltage of the battery in a resting state to converge and stabilize to a constant level enough to estimate the Nernst OCV. For example, the Nernst OCV stabilization time may be approximately 12 hours or more or 24 hours or more. As the Nernst OCV stabilization time increases, cost and time are consumed, so it needs to be shortened.

The present invention measures the voltage (V _c ) after applying the charging pulse current and the voltage (V _d ) after applying the discharging pulse, and the average voltage values of the V _c and V _d are not significantly different from the actual Nernst OCV of the battery. Confirmed. The present invention has technical significance in that the Nernst OCV can be estimated through the CCV without passing through the Nernst OCV stabilization time.

The technical meaning of the present invention is explained as follows.

An electrochemical reaction means an oxidation or reduction reaction in which electrons are involved. In general, when a current is applied (electrons flow) for an electrochemical reaction, an electrochemical reaction in which electrons are involved occurs, as well as an electrochemical reaction in which charges are accumulated on the surface of an electrode, such as an electric double-layer Electrons are also used for other purposes. At this time, the current required for the electrochemical reaction is referred to as faradaic current, and the current required for purposes other than the electrochemical reaction, such as generating an electrical double layer, is referred to as non-faradaic current.

For example, when a current is applied to a battery, a reaction by the Faraday current may be an oxidation/reduction reaction of a battery electrode, and a thermodynamic state of a corresponding electrode may change due to the oxidation/reduction reaction. Therefore, the reaction by the Faraday current can be interpreted as a change in the energy level of the electrode, that is, the thermodynamic energy level of the electrode.

In contrast, when a current is applied to the battery, the reaction by the non-Faraday current may be an electric double layer generation reaction generated on the surface of the battery electrode, and this reaction is when electrons are consumed (current is applied) but electrons are transferred to the electrode. Since it is not oxidized/reduced while moving, the energy level of the battery does not change. Therefore, the reaction by the non-Faraday current can be interpreted as a reaction in which the energy level of the electrode, that is, the thermodynamic energy level of the electrode does not change.

Therefore, in order to obtain only the thermodynamic energy information of the battery when a current is applied to the battery, it is necessary to measure the energy level change value due to the Faraday current. Since they appear simultaneously, it is difficult to detect only the state change of the battery based on the Faraday current.

In the present invention, a charge pulse current and a discharge pulse current having the same charge capacity/discharge capacity are alternately flowed, and an average voltage value of voltage values changed accordingly is estimated as Nernst OCV. At this time, since the total amount of the applied charge pulse current and discharge pulse current is the same, among the various electrochemical reactions caused by the application of the pulse current, the reaction caused by the non-Faraday current is canceled out, and only the reaction caused by the Faraday current is observed. can be thought of as being

Therefore, the average value of the voltage changed according to the application of the pulse current can be considered as the thermodynamic information (OCV) of the battery, and it is considered that there is no large error when this value is compared with the actual Nernst OCV.

5 shows a comparison between the Nernst OCV estimated through the method of the present invention and the actual Nernst OCV. 5 shows an example of an experiment using a battery in the form of a pack and a module. The actual Nernst OCV is a measurement of the convergence voltage by storing the battery under the same conditions in an open circuit state for 24 hours, and the estimated Nernst OCV shows the Nernst OCV estimated using the method of the present invention. Referring to FIG. 5 , it can be confirmed that the error rates of the actual Nernst OCV and the estimated Nernst OCV are very small in units of 100 ppm, and through this, it can be confirmed that the Nernst OCV estimated using the method of the present invention is a highly reliable value.

Meanwhile, the battery state estimation method according to an embodiment of the present invention includes calculating the SOC using the Nernst OCV estimated by the method of the present invention (S600).

In a specific embodiment of the present invention, calculating the SOC using the estimated Nernst OCV may include calculating the SOC by referring to a reference table corresponding to the estimated Nernst OCV. For example, a reference table corresponding to the estimated Nernst OCV may be made into a database and stored in the charge/discharge device in advance, and SOC may be calculated by matching the estimated Nernst OCV to the previously stored reference table. The database may be implemented as a memory included in the charging/discharging device or as an external device such as a server that can be connected to the battery state estimation device by wire, wireless, or network. Reference table corresponding to the OCV estimated by the method of the present invention Since the reference table is used, it is possible to eliminate the hassle of separately managing a reference table corresponding to the previous battery state, and to reduce an error in estimating the battery state due to OCV hysteresis.

In another embodiment of the present invention, SOC may be calculated by substituting the Nernst OCV estimated in the present invention into a specific formula. The above formula may use a known formula, and is not limited to a specific formula.

The battery state estimation method according to an embodiment of the present invention may perform the above-described Nernst OCV estimation step and SOC calculation step multiple times. Specifically, the battery state estimation method of the present invention may perform Nernst OCV estimation and SOC calculation multiple times (one time, two times, three times, etc.) in different SOC intervals. In order to perform Nernst OCV estimation and SOC calculation in different SOC intervals, the battery may be partially charged or discharged between each cycle (see FIG. 6). For example, as shown in FIG. 6 , after calculating SOC 1 in section A, the battery may be discharged for a certain period of time, and then SOC 2 may be calculated in section B.

Here, between the plurality of rounds of SOC calculation, only a portion of the total capacity of the battery is charged or discharged to calculate the SOC in a different state of charge. At this time, charging or discharging of the battery may be performed only in the range of 10% to 50% of the total capacity of the battery.

Meanwhile, a method for estimating a battery state according to an embodiment of the present invention includes calculating ΔSOC using SOC calculated by performing multiple times, and calculating a capacity life (SOH) of a battery using ΔSOC. Do (S700).

In the present invention, capacity life (SOH) represents the degree of aging of a battery. Regarding the capacity life (SOH), a battery that is not aged at all is represented by SOH 100%, and conversely, a state in which the battery is unusable due to continued aging can be represented by SOH 0%.

Here, the capacity life (SOH) may be calculated through the formula below, but is not limited to a specific formula.

[Equation 1]

Capacity lifetime (SOH)=Q _occupied /(Capacity _nominal △SOC)

Here, Q _occupied isMeans the total amount of applied current,

Capacity _nominal means nominal capacity.

ΔSOC = SOC2 - SOC1

The battery state estimation method according to the present invention may be implemented and used in at least one software module. For example, the battery state estimation method may be implemented by a battery management system (BMS).

Meanwhile, the present invention determines the SOC of the battery, applies a charging current or a discharging current based on the SOC determination result, applies at least one charging pulse current and at least one discharging pulse current to the battery, and applies the charging pulse current. A battery state including a processor that measures the voltage V _c changed when current is applied, measures the voltage V _d changed when discharge pulse current is applied, and estimates the average value of the V _c and V _d as Nernst OCV. Estimation device is provided.

Here, the battery state estimation apparatus of the present invention may include a processor and a memory, and the processor may perform the battery state estimation method of the present invention. The memory may store a reference table corresponding to the stabilized Nernst OCV or may store a program in which a battery state estimation method is implemented. The memory may be volatile memory or non-volatile memory. The processor may execute the program and control the battery state estimation device. Program codes executed by the processor may be stored in memory. The battery state estimation device may be connected to an external device (eg, a personal computer or network) through an input/output device (not shown) and exchange data.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, the described techniques may be performed in an order different from the methods described, and/or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the methods described, or in a different configuration. Appropriate results can be achieved even when substituted or substituted by elements or equivalents. Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

Claims

(S100) determining the SOC of the battery;

(S200) based on the SOC determination result, applying a charging current or a discharging current to the battery;

(S300) applying at least one charge pulse current and at least one discharge pulse current to the battery;

(S400) measuring the changed voltage V c when the charging pulse current is applied, and measuring the changed voltage V d when the discharge pulse current is applied;

(S500) estimating the average value of V c and V d as the Nernst OCV of the battery;

Including, battery state estimation method.
According to claim 1,

When the SOC of the battery determined in step (S100) is less than the reference SOC, a charging current is applied in step (S200),

If the SOC of the battery determined in step (S100) is greater than or equal to the reference SOC, a discharge current is applied in step (S200).
According to claim 2,

The reference SOC is a point between 20% and 80% SOC, battery state estimation method.
According to claim 1,

At least one charging pulse current and at least one discharging pulse current of step (S300) are alternately applied, the battery state estimation method.
According to claim 4,

The pulse current applied in step (S300) is that the pulse current of the opposite sign to the current applied in step (S200) is first applied.
According to claim 1,

The total charging capacity (Ah) by at least one charging pulse current applied in step (S300) and the total discharging capacity (Ah) by at least one discharging pulse current are equal to each other.
According to claim 1,

The magnitude of at least one pulse current applied in step (S300) is 0.1 C-rate to 10.0 C-rate, and the time for applying each pulse current is 0.1 second to 500 seconds.
According to claim 1,

At least one pause step is inserted between the at least one charge pulse current and at least one discharge pulse current applying step of step (S300),

How to estimate battery health.
According to claim 8,

wherein the idle step is maintained for 0.1 to 500 seconds, or 0.1 to 120 seconds.
According to claim 8,

The total time (τ A ) during which at least one charging pulse current is applied in step S300 and the total time (τ B ) during which at least one discharging pulse is applied are equal to each other.
According to claim 10,

Wherein the idle step is maintained for 0.1·τ A to 10·τ A.
According to claim 1,

The average of step (S500) is calculated by any one or a combination of arithmetic average, geometric average, and harmonic average, battery state estimation method.
According to claim 1,

(S600) A method for estimating a battery state, further comprising calculating an SOC of the battery using the estimated Nernst OCV.
According to claim 13,

The step of calculating the SOC of the battery is to calculate the SOC by referring to a reference table corresponding to the estimated Nernst OCV.
According to claim 13,

Wherein the step of calculating the SOC of the battery is performed multiple times.
According to claim 15,

(S700) The battery state estimation method further comprises calculating a capacity life (SOH) based on the calculated SOC multiple times.
determine the SOC of the battery,

Based on the SOC determination result, a charging current or a discharging current is applied to the battery,

applying at least one charge pulse current and at least one discharge pulse current to the battery;

Measuring the voltage V c changed when the charging pulse current was applied, and measuring the voltage V d changed when the discharge pulse current was applied,

An apparatus for estimating battery state, including a processor for estimating an average value of V c and V d as Nernst OCV.