阅读说明：本技术 用于确定电池劣化度的设备和方法及包括设备的电池组 (Apparatus and method for determining degree of degradation of battery and battery pack including the same ) 是由 车阿明 裵允玎 于 2020-05-07 设计创作，主要内容包括：提供了用于一种确定电池的劣化度的设备、方法及电池组。该设备生成第一感测信息,该第一感测信息指示在以第一恒定电流对电池充电时电池的电压和电流。该设备生成第二感测信息,该第二感测信息指示在以第二恒定电流对电池进行放电的第二时段期间电池的电压和电流。该设备基于第一感测信息来确定第一差分容量曲线并且基于第二感测信息来确定第二差分容量曲线。该设备被配置为基于第一差分容量曲线的第一充电特征点的电压值和第二差分容量曲线的第一放电特征点的电压值来确定电池的劣化度。(Provided are an apparatus, a method, and a battery pack for determining a degree of degradation of a battery. The apparatus generates first sensing information indicating a voltage and a current of a battery when the battery is charged at a first constant current. The device generates second sensing information indicating a voltage and a current of the battery during a second period in which the battery is discharged at a second constant current. The device determines a first differential capacity curve based on the first sensed information and a second differential capacity curve based on the second sensed information. The apparatus is configured to determine a degree of degradation of the battery based on a voltage value of a first charging characteristic point of the first differential capacity curve and a voltage value of a first discharging characteristic point of the second differential capacity curve.)

1. An apparatus for determining a degree of degradation of a battery, the apparatus comprising:

a sensing unit configured to generate first sensing information indicating a voltage and a current of the battery during a first period in which the battery is charged at a first constant current and second sensing information indicating a voltage and a current of the battery during a second period in which the battery is discharged at a second constant current; and

a control unit operably coupled to the sensing unit,

wherein the control unit is configured to:

determining a first differential capacity curve of the battery based on the first sensed information;

detecting a first charging characteristic point from the first differential capacity curve,

determining a second differential capacity curve of the battery based on the second sensed information;

detecting a first discharge characteristic point from the second differential capacity curve, an

Determining a degree of degradation of the battery based on the first charge characteristic value and the first discharge characteristic value;

wherein the first charging characteristic value is a voltage value of the first charging characteristic point, and

the first discharge characteristic value is a voltage value of the first discharge characteristic point.

2. The device of claim 1, wherein the control unit is configured to:

determining a peak positioned in a first predetermined order among a predetermined number of peaks located on the first differential capacity curve as the first charging feature point, and

determining a peak located in the first predetermined order among a predetermined number of peaks located on the second differential capacity curve as the first discharge characteristic point.

3. The device of claim 2, wherein the control unit is configured to determine a first dominant difference value indicative of an absolute value of a difference between the first charge characteristic value and the first discharge characteristic value.

4. The apparatus according to claim 3, wherein the control unit is configured to determine the degree of degradation of the battery from a first data table that records a correlation between the first main difference value and the degree of degradation, using the first main difference value as an index.

5. The device of claim 2, wherein the control unit is configured to:

when the predetermined number is 2 or more,

determining a peak located in a second predetermined order among the predetermined number of peaks located on the first differential capacity curve as a second charging feature point,

determining peaks located in the second predetermined order among the predetermined number of peaks located on the second differential capacity curve as second discharge characteristic points, and

determining a second dominant difference value indicative of an absolute value of a difference between the second charge characteristic value and the second discharge characteristic value;

wherein the second charging characteristic value is a voltage value of the second charging characteristic point, and

the second discharge characteristic value is a voltage value of the second discharge characteristic point.

6. The device of claim 5, wherein, when the predetermined number is 2, the control unit is configured to:

the first degradation factor is determined using the following equation:

[ formula ]

Wherein, is Δ V_iIs the ith main difference value, alpha_iIs the ith predetermined weight, and F_degIs the first degradation factor, and

determining a degree of degradation of the battery from a second data table that records a correlation between the first degradation factor and the degree of degradation using the first degradation factor as an index.

7. The device of claim 1, wherein the control unit is configured to:

determining a first sub-difference value indicative of an absolute value of a difference between the first charging characteristic value and a first initial charging characteristic value,

determining a second sub-difference value indicative of an absolute value of a difference between the first discharge characteristic value and the first initial discharge characteristic value, and

determining a degree of degradation of the battery based on the first sub-difference value and the second sub-difference value.

8. The device of claim 7, wherein the control unit is configured to:

determining a sum of a product of the first sub-difference value and the first transform coefficient and a product of the second sub-difference value and the second transform coefficient as a second degradation factor, and

determining a degree of degradation of the battery from a third data table that records a correlation between the second degradation factor and the degree of degradation using the second degradation factor as an index.

9. A battery pack comprising the apparatus according to any one of claims 1 to 8.

10. A method for determining a degree of degradation of a battery, the method comprising:

acquiring first sensing information indicating a voltage and a current of a battery during a first period in which the battery is charged at a first constant current;

acquiring second sensing information indicating a voltage and a current of the battery during a second period in which the battery is discharged at a second constant current;

determining a first differential capacity curve of the battery based on the first sensed information;

determining a second differential capacity curve of the battery based on the second sensed information;

detecting a first charging characteristic point from the first differential capacity curve;

detecting a first discharge characteristic point from the second differential capacity curve; and

determining a degree of degradation of the battery based on the first charge characteristic value and the first discharge characteristic value;

wherein the first charging characteristic value is a voltage value of the first charging characteristic point, and

the first discharge characteristic value is a voltage value of the first discharge characteristic point.

11. The method of claim 10, wherein determining the degree of degradation of the battery comprises:

determining a first dominant difference value indicative of an absolute value of a difference between the first charge characteristic value and the first discharge characteristic value; and

determining a degree of deterioration of the battery from a first data table recording a correlation between the first main difference value and the degree of deterioration using the first main difference value as an index.

Technical Field

The present disclosure relates to a technique for determining a degree of deterioration of a battery.

The present application claims priority from korean patent application No.10-2019-0056467 filed in korea at 14.5.2019, the disclosure of which is incorporated herein by reference.

Background

Recently, the demand for portable electronic products such as laptop computers, video cameras, and mobile phones has sharply increased, and with the widespread development of electric cars, energy accumulators, robots, and satellites, many studies are being conducted on high-performance batteries capable of being repeatedly charged.

Currently, commercially available batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, etc., wherein the lithium batteries have little or no memory effect and thus are receiving more attention than the nickel-based batteries, and the lithium batteries have advantages in that they can be charged at a convenient time, have a very low self-discharge rate, and have a high energy density.

The degree of degradation of the battery is determined from a capacity curve indicating a correlation between the voltage and the remaining capacity of the battery. However, in the capacity curve, there is a remaining capacity range in which a voltage change is not clearly observed, and it is difficult to accurately determine the degree of degradation of the battery.

To overcome the disadvantages of the capacity curve, a Differential Voltage Analysis (DVA) may be used to determine the degree of degradation of the battery from the differential voltage curve of the battery. However, the differential voltage curve obtained by performing only one of the charging process and the discharging process of the battery is not sufficient to include information on the hysteresis characteristic of the battery.

Disclosure of Invention

Technical problem

The present disclosure is designed to solve the above-described problems, and therefore, the present disclosure is directed to providing an apparatus, a method, and a battery pack for determining a degree of degradation of a battery using both a differential capacity curve acquired from a charging process of the battery and a differential capacity curve acquired from a discharging process of the battery.

These and other objects and advantages of the present disclosure will be understood by the following description, and will be apparent from the embodiments of the present disclosure. Further, it will be readily understood that the objects and advantages of the present disclosure may be realized by the means set forth in the appended claims and combinations thereof.

Technical scheme

An apparatus for determining a degree of degradation of a battery according to an aspect of the present disclosure includes: a sensing unit configured to generate first sensing information indicating a voltage and a current of a battery during a first period in which the battery is charged at a first constant current and second sensing information indicating a voltage and a current of the battery during a second period in which the battery is discharged at a second constant current; and a control unit operably coupled to the sensing unit. The control unit is configured to determine a first differential capacity curve of the battery based on the first sensing information. The control unit is configured to detect a first charging characteristic point from the first differential capacity curve. The control unit is configured to determine a second differential capacity curve of the battery based on the second sensing information. The control unit is configured to detect a first discharge characteristic point from the second differential capacity curve. The control unit is configured to determine a degree of degradation of the battery based on the first charge characteristic value and the first discharge characteristic value. The first charging characteristic value is a voltage value of the first charging characteristic point. The first discharge characteristic value is a voltage value of the first discharge characteristic point.

The control unit may be configured to determine, as the first charging characteristic point, a peak located in a first predetermined order among a predetermined number of peaks located on the first differential capacity curve. The control unit may be configured to determine a peak positioned in a first predetermined order among a predetermined number of peaks located on the second differential capacity curve as the first discharge characteristic point.

The control unit may be configured to determine a first dominant difference value indicative of an absolute value of a difference between the first charging characteristic value and the first discharging characteristic value. The control unit may be configured to determine the degree of degradation of the battery from a first data table recording a correlation between the first dominant difference and the degree of degradation using the first dominant difference as an index.

When the predetermined number is 2 or more, the control unit may be configured to determine a peak positioned in a second predetermined order among the predetermined number of peaks located on the first differential capacity curve as the second charging feature point. The control unit may be configured to determine a peak positioned in a second predetermined order among a predetermined number of peaks located on the second differential capacity curve as the second discharge characteristic point. The control unit may be configured to determine a second dominant difference value indicative of an absolute value of a difference between the second charge characteristic value and the second discharge characteristic value. The second charging characteristic value is a voltage value of the second charging characteristic point. The second discharge characteristic value is a voltage value of the second discharge characteristic point.

When the predetermined number is 2, the control unit may be configured to determine the first degradation factor using the following formula:

[ formula ]

Wherein, is Δ V_iIs the ith main difference value, alpha_iIs the ith predetermined weight, and F_degIs the first degradation factor. The control unit may be configured to determine the degree of degradation of the battery from a second data table that records a correlation between the first degradation factor and the degree of degradation using the first degradation factor as an index.

The control unit may be configured to determine a first sub-difference value indicative of an absolute value of a difference between the first charging characteristic value and the first initial charging characteristic value. The control unit may be configured to determine a second sub-difference value indicative of an absolute value of a difference between the first discharge characteristic value and the first initial discharge characteristic value. The control unit may be configured to determine the degree of degradation of the battery based on the first sub-difference value and the second sub-difference value.

The control unit may be configured to determine a sum of a product of the first sub-difference value and the first transform coefficient and a product of the second sub-difference value and the second transform coefficient as the second degradation factor. The control unit may be configured to determine the degree of degradation of the battery from a third data table that records a correlation between the second degradation factor and the degree of degradation using the second degradation factor as an index.

A battery pack according to another aspect of the present disclosure includes the apparatus.

A method for determining a degree of degradation of a battery according to still another aspect of the present disclosure includes: acquiring first sensing information indicating a voltage and a current of a battery during a first period in which the battery is charged at a first constant current; acquiring second sensing information indicating a voltage and a current of the battery during a second period in which the battery is discharged at a second constant current; determining a first differential capacity curve of the battery based on the first sensing information; determining a second differential capacity curve of the battery based on the second sensing information; detecting a first charging characteristic point from the first differential capacity curve; detecting a first discharge characteristic point from the second differential capacity curve; and determining a degree of degradation of the battery based on the first charge characteristic value and the first discharge characteristic value. The first charging characteristic value is a voltage value of the first charging characteristic point. The first discharge characteristic value is a voltage value of the first discharge characteristic point.

Determining the degree of degradation of the battery may include: determining a first dominant difference value indicative of an absolute value of a difference between the first charge characteristic value and the first discharge characteristic value; and determining a degree of deterioration of the battery from a first data table using the first dominant difference as an index, the first data table recording a correlation between the first dominant difference and the degree of deterioration.

Technical effects

According to at least one of the embodiments of the present disclosure, the degree of degradation of the battery may be determined using both a differential capacity curve obtained from a charging process of the battery and a differential capacity curve obtained from a discharging process of the battery. The hysteresis characteristic of the battery has a strong correlation with the degree of degradation of the battery, and therefore, in the case where two differential capacity curves are used, the degree of degradation of the battery can be determined more accurately than in the case where only one differential capacity curve is used.

The effects of the present disclosure are not limited to the above-described effects, and these and other effects will be clearly understood by those skilled in the art from the appended claims.

Drawings

The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the disclosure described below, serve to provide a further understanding of the technical aspects of the disclosure, and therefore, the disclosure should not be construed as being limited to the accompanying drawings.

Fig. 1 is a diagram illustrating the configuration of a battery pack according to an embodiment of the present disclosure.

Fig. 2 is a diagram illustrating a capacity curve of a battery when the battery is at an initial stage of life.

FIG. 3 is a graph illustrating a differential capacity curve determined from the capacity curve of FIG. 2.

Fig. 4 is a diagram illustrating a differential capacity curve of a battery when the battery at the initial stage of life deteriorates.

Fig. 5 is a flowchart illustrating a method for determining a degree of degradation of a battery according to a first embodiment of the present disclosure.

Fig. 6 is a flowchart illustrating a method for determining a degree of degradation of a battery according to a second embodiment of the present disclosure.

Fig. 7 is a flowchart illustrating a method for determining a degree of degradation of a battery according to a third embodiment of the present disclosure.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms for the best explanation.

Therefore, the embodiments described herein and the illustrations shown in the drawings are only the most preferred embodiments of the present disclosure, but are not intended to fully describe the technical aspects of the present disclosure, and therefore it should be understood that various other equivalents and modifications can be made at the time of filing this application.

Terms including ordinal numbers such as "first," "second," etc., are used to distinguish one element from another element among the various elements, but are not intended to limit the elements by the terms.

Unless the context clearly dictates otherwise, it should be understood that the term "comprising" when used in this specification indicates the presence of the mentioned elements, but does not preclude the presence or addition of one or more other elements. In addition, the term "control unit" used herein refers to at least one processing unit of functions or operations, and may be implemented by hardware or software, alone or in combination.

In addition, throughout the specification, it will be further understood that when an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may be present.

Fig. 1 is a diagram illustrating the configuration of a battery pack according to an embodiment of the present disclosure.

Referring to fig. 1, a battery pack 10 is provided to be installed in an electrical system 1 (e.g., an electric vehicle), and includes a battery B, a switch SW, and a device 100.

The positive and negative terminals of battery B are electrically connected to device 100. The battery B includes at least one unit cell. The unit cells may be, for example, lithium ion batteries. The type of unit cells is not limited to the lithium ion battery, and any other type of battery unit that can be repeatedly recharged may be used as the unit cells.

The switch SW is installed on a current path for charging and discharging the battery B. When the switch SW is turned on, the battery B may be charged and discharged. The switch SW may be a mechanical relay or a semiconductor switch such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) that is turned on or off by magnetic force of a coil. When switch SW is turned off, charging and discharging of battery B stops. The switch SW may be turned on in response to the first switch signal. The switch SW may be turned off in response to the second switching signal.

The apparatus 100 is arranged to determine the degree of degradation of the battery B. The degree of deterioration may be a value that increases as battery B deteriorates.

The apparatus 100 includes a sensing unit 110, a control unit 120, and a storage unit 130. The device 100 may further include at least one of an interface unit 140 and a switch driver 200.

The sensing unit 110 includes a voltage sensor 111 and a current sensor 112.

The voltage sensor 111 is electrically connected to the positive terminal and the negative terminal of the battery B. The voltage sensor 111 is configured to measure the voltage across the battery B every unit time (for example, 0.01 second) while the battery B is charged or discharged. The current sensor 112 is mounted on the charge/discharge path of the battery B. The current sensor 112 is configured to measure the current of the battery B every unit time while the battery B is charged or discharged.

The sensing unit 110 is configured to output sensing information indicating the voltage and current of the battery B per unit time to the control unit 120.

The control unit 120 may be implemented in hardware using at least one of an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), a microprocessor, and an electrical unit for performing other functions.

The control unit 120 is operatively coupled to at least one of the sensing unit 110, the storage unit 130, the interface unit 140, and the switch driver 200.

The control unit 120 may command the switch driver 200 to turn on the switch SW when at least one of the predetermined events occurs. In other cases, the control unit 120 may command the switch driver 200 to turn off the switch SW.

Control unit 120 is configured to store data indicating the voltage history, current history, and remaining capacity history of battery B in storage unit 130 based on the sensing information from sensing unit 110. The history of a parameter refers to the time-series change of the corresponding parameter over a certain or specific period of time. The voltage history, current history, and remaining capacity history of battery B may be voltage history, current history, and remaining capacity history for the same or different periods. The remaining capacity of battery B indicates the amount of charge stored in battery B.

Control unit 120 determines a first capacity curve and a second capacity curve for battery B.

The first capacity curve indicates a correlation between a voltage history and a remaining capacity history acquired during a period (hereinafter referred to as a "first period") in which battery B is charged from below a first state of charge (SOC) (e.g., 5%) to above a second SOC (e.g., 95%) at a constant current (e.g., 0.02C) at a first current rate. The first capacity curve is based on first sensing information indicating the voltage and current of the battery B per unit time output by the sensing unit 110 during the first period. The control unit 120 may control the switch driver 200 to allow a charging current of a first current rate to flow through the battery B for a first period.

The second capacity curve indicates a correlation between the voltage history and the remaining capacity history acquired for a period in which battery B is discharged from above the second SOC to below the first SOC (hereinafter referred to as "second period") at a constant current of the second current rate. The second capacity curve is based on second sensing information indicating the voltage and current of the battery B per unit time output by the sensing unit 110 during the second period. The control unit 120 may control the switch driver 200 to allow a discharge current of a second current rate to flow through the battery B for a second period. The second current rate may be equal to or different from the first current rate.

The control unit 120 may determine a voltage variation dV and a remaining capacity variation dQ of the battery B per unit time from the first capacity curve. The control unit 120 may store a first data set indicating the correlation of the voltage V, the remaining capacity Q, the voltage change dV, and the remaining capacity change dQ of the battery B per unit time, which are determined from the first capacity curve, in the storage unit 130.

The control unit 120 may determine a first differential capacity curve from the first data set. The first differential capacity curve indicates a relationship between a ratio dQ/dV of a remaining capacity change dQ of the battery B to a voltage change dV of the battery B and the voltage V of the battery B in the first period, and may be referred to as a first V-dQ/dV curve.

The control unit 120 may determine a voltage change dV and a remaining capacity change dQ of the battery B per unit time from the second capacity curve. The control unit 120 may store a second data set indicating the correlation of the voltage V, the remaining capacity Q, the voltage change dV, and the remaining capacity change dQ of the battery B per unit time, which are determined from the second capacity curve, in the storage unit 130.

The control unit 120 may determine a second differential capacity curve from the second data set. The second differential capacity curve indicates a relationship between a ratio dQ/dV of a remaining capacity change dQ of the battery B to a voltage change dV of the battery B and the voltage V of the battery B in the second period, and may be referred to as a second V-dQ/dV curve.

The storage unit 130 is operatively coupled to the control unit 120. The storage unit 130 may also be operably coupled to the sensing unit 110. The storage unit 130 is configured to store sensing information from the sensing unit 110. The storage unit 130 may store data and programs required for the calculation operation by the control unit 120. The storage unit 130 may store data indicating the result of the calculation operation performed by the control unit 120.

The storage unit 130 may include at least one type of storage medium such as a flash memory type, a hard disk type, a Solid State Disk (SSD) type, a Silicon Disk Drive (SDD) type, a micro multimedia card type, a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read Only Memory (ROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), and a Programmable Read Only Memory (PROM).

The switch driver 200 is electrically coupled to the apparatus 100 and the switch SW. The switch driver 200 is configured to selectively output a first switch signal or a second switch signal to the switch SW in response to a command from the apparatus 100.

The interface unit 140 is configured to support wired or wireless communication between the control unit 120 and a high-level controller 2 (e.g., an Electronic Control Unit (ECU)) of the electrical system 1. The wired communication may be, for example, Controller Area Network (CAN) communication, and the wireless communication may be, for example, Zigbee (Zigbee) or Bluetooth (Bluetooth) communication. The communication protocol is not limited to a particular type, and may include any type of communication protocol that supports wired or wireless communication between the control unit 120 and the advanced controller 2. The interface unit 140 may include an output device such as a display or a speaker to provide the processing result regarding the degree of degradation of the battery B performed by the control unit 120 in a form allowing the user to recognize. The interface unit 140 may include input devices such as a mouse and a keyboard to receive data input from a user.

Fig. 2 is a diagram illustrating a capacity curve of a battery when the battery is at an initial life (BOL), and fig. 3 is a diagram illustrating a differential capacity curve determined from the capacity curve of fig. 2.

Maximum capacity Q of battery B_maxIt may be the remaining capacity of battery B when battery B is fully charged (i.e., when the SOC of battery B is 100%). As battery B deteriorates, maximum capacity Q of battery B_maxGradually decreases.

Referring to fig. 2, a capacity curve 201 indicates a correlation between a voltage V and a remaining capacity Q of battery B obtained by a charging process of charging battery B at a constant current of a predetermined current rate such that the SOC of battery B at BOL increases from 0% to 100%.

The capacity curve 202 indicates a correlation between the voltage V of the battery B and the remaining capacity Q, which is obtained by a discharge process of discharging the battery B at a constant current of a predetermined current rate such that the SOC of the battery B at the BOL is reduced from 100% to 0%.

In the remaining capacity ranges 0 and Q due to the hysteresis characteristic of battery B_maxIn at least a part therebetween, the difference between the voltage of the capacity curve 201 and the voltage of the capacity curve 202 at the same remaining capacity is equal to or larger than a predetermined threshold value.

Referring to fig. 3, a differential capacity curve 301 is determined from the relationship between the voltage history and the remaining capacity history indicated by the capacity curve 201. Differential capacity curve 302 is determined from the relationship between the voltage history and remaining capacity history indicated by capacity curve 202. For ease of understanding, the differential capacity curve 301 and the differential capacity curve 302 are shown above and below, respectively, dQ/dV being 0 Ah/V.

Peak P located on differential capacity curve 301_{CI_1}、P_{CI_2}、P_{CI_3}And peak P located on the differential capacity curve 302_{DI_1}、P_{DI_2}、P_{DI_3}The total number of (a) may be equal. The total number of peaks located on each of the differential capacity curve 301 and the differential capacity curve 302 depends on the electrode material of the battery B and the like. Therefore, even if battery B deteriorates, the total number of peaks located on each of differential capacity curve 301 and differential capacity curve 302 may be constant. Hereinafter, it is assumed that the peak P appearing in the differential capacity curve 301_{CI_1}、P_{CI_2}、P_{CI_3}Sum of peaks P on the differential capacity curve 302_{DI_1}、P_{DI_2}、P_{DI_3}Are each 3.

The storage unit 130 may store peaks P respectively indicating positions on the differential capacity curve 301_{CI_1}、P_{CI_2}、P_{CI_3}Voltage value V of peak of_{CI_1}、V_{CI_2}、V_{CI_3}Is detected (referred to as "initial charging characteristic value").

The storage unit 130 may store peaks P respectively indicating positions on the differential capacity curve 302_{DI_1}、P_{DI_2}、P_{DI_3}Voltage value V of_{DI_1}、V_{DI_2}、V_{DI_3}Is determined (referred to as "initial discharge characteristic value").

The inventors have recognized from the results of charge-discharge tests of batteries of the same specification as that of battery B that the hysteresis characteristics of battery B become more severe as battery B deteriorates.

Fig. 4 is a diagram illustrating a differential capacity curve of a battery when the battery at BOL is deteriorated.

Referring to fig. 4, a differential capacity curve 401 is determined according to a relationship between a voltage history and a remaining capacity history of a first period. The differential capacity curve 402 is determined from a relationship between the voltage history and the remaining capacity history for the second period of time. For ease of understanding, a differential capacity curve 401 and a differential capacity curve 402 are shown above and below dQ/dV ═ 0.

The differential capacity curve 401 has a peak P that is similar to the peak P appearing in the differential capacity curve 301_{CI_1}、P_{CI_2}、P_{CI_3}Same number of peaks P_{CD_1}、P_{CD_2}、P_{CD_3}. The differential capacity curve 402 has a peak P that is similar to the peak P in the differential capacity curve 302_{DI_1}、P_{DI_2}、P_{DI_3}Same number of peaks P_{DD_1}、P_{DD_2}、P_{DD_3}。

In the differential capacity curve 401, the peak P_{CD_1}Peak P of_{CD_2}He Feng_{PCD_3}In ascending order of remaining capacity. Peak P appearing in differential capacity curve 401_{CD_1}、P_{CD_2}、P_{CD_3}Respectively corresponding to the peaks P appearing in the differential capacity curve 301_{CI_1}、P_{CI_2}、P_{CI_3}. Peak P_{CD_1}、P_{CD_2}、P_{CD_3}May be referred to as "charging characteristic point", and peak P_{CD_1}、P_{CD_2}、P_{CD_3}Voltage value V of_{CD_1}、V_{CD_2}、V_{CD_3}May be referred to as a "charge characteristic value".

In the differential capacity curve 402, the peak P_{DD_1}Peak P of_{DD_2}Sum peak P_{DD_3}In ascending order of remaining capacity. Peak P appearing in differential capacity curve 402_{DD_1}、P_{DD_2}、P_{DD_3}Respectively corresponding to the peaks P appearing in the differential capacity curve 302_{DI_1}、P_{DI_2}、P_{DI_3}. Peak P_{DD_1}、P_{DD_2}、P_{DD_3}May be referred to as "discharge characteristic point", and the peak P_{DD_1}、P_{DD_2}、P_{DD_3}Voltage value V of_{DD_1}、V_{DD_2}、V_{DD_3}May be referred to as "discharge characteristic value".

Referring to fig. 2 to 4, it can be seen that, as battery B deteriorates, (I) peak P located on differential capacity curve 401_{CD_1}、P_{CD_2}、P_{CD_3}V of_{CD_1}、V_{CD_2}、V_{CD_3}From the peak P located on the differential capacity curve 301 in the same order_{CI_1}、P_{CI_2}、P_{CI_3}Initial charging characteristic value V_{CI_1}、V_{CI_2}、V_{CI_3}Starting to increase; and (II) a peak P located on the differential capacity curve 402_{DD_1}、P_{DD_2}、P_{DD_3}V of_{DD_1}、V_{DD_2}、V_{DD_3}From the peak P located on the differential capacity curve 302 in the same order_{DI_1}、P_{DI_2}、P_{DI_3}Initial discharge characteristic value V_{DI_1}、V_{DI_2}、V_{DI_3}The decrease is started. That is, as battery B deteriorates, peak P of differential capacity curve 401_{CD_1}、P_{CD_2}、P_{CD_3}Moving to higher voltages while differentiating the peak P of the capacity curve 402_{DD_1}、P_{DD_2}、P_{DD_3}Moving towards lower voltages.

The inventors have discovered that two peaks (e.g., P) that appear in the same order (e.g., first order) on the differential capacity curve 401 and the differential capacity curve 402_{CD_1}、P_{DD_1}) Voltage value of (e.g. V)_{CD_1}、V_{DD_1}) The difference therebetween has a strong correlation with the degree of deterioration of battery B.

Fig. 5 is a flowchart illustrating a method for determining a degree of degradation of a battery according to an embodiment of the present disclosure. The method of fig. 5 may be used to determine the degree of degradation of the battery in the presence of at least one peak on the differential capacity curve B.

Referring to fig. 1 to 5, in step S502, the control unit 120 acquires first sensing information indicating a voltage and a current of the battery B during a first period in which the battery B is charged at a first constant current from the sensing unit 110.

In step S504, the control unit 120 acquires second sensing information indicating the voltage and current of the battery B during a second period in which the battery B is discharged at a second constant current from the sensing unit 110.

In step S512, the control unit 120 determines a first differential capacity curve of the battery B based on the first sensing information. For example, the first differential capacity curve may be the differential capacity curve 401 of fig. 4.

In step S514, control unit 120 determines a second differential capacity curve of battery B based on the second sensing information. For example, the second differential capacity curve may be the differential capacity curve 402 of fig. 4.

In step S522, the control unit 120 detects a charging characteristic point (e.g., P) from the first differential capacity curve_{CD_2}). Characteristic point of charge (e.g., P)_{CD_2}) May be peaks located in a predetermined order (e.g., a second order) based on the remaining capacity among all peaks of the first differential capacity curve.

In step S524, the control unit 120 detects a discharge characteristic point (e.g., P) from the second differential capacity curve_{DD_2}). Discharge characteristic point (e.g., P)_{DD_2}) May be peaks located in a predetermined order (e.g., the second order) based on the remaining capacity among all peaks of the second differential capacity curve.

In step S530, the control unit 120 determines the degree of deterioration of the battery B based on the main difference value. The main difference value is a charging characteristic value (e.g., V)_{CD_2}) And a discharge characteristic value (e.g., V)_{DD_2}) Absolute value of the difference therebetween (e.g., | V)_{CD_2}-V_{DD_2}| an). Characteristic value of charge (e.g. V)_{CD_2}) Is a charging characteristic point (e.g., P)_{CD_2}) Voltage value of (d), and discharge characteristic value (e.g., V)_{DD_2}) Is a discharge characteristic point (e.g., P)_{DD_2}) The voltage value of (2). The control unit 120 determines the degree of degradation of the battery B from the first data table, which records the correlation between the main difference value determined in step S530 and the degree of degradation, using the main difference value as an index.

The first data table may be stored in the storage unit 130. As the hysteresis characteristic of battery B becomes stronger, the dominant difference tends to increase. Therefore, in the first data table, a larger dominant difference value may be associated with a higher degree of deterioration.

Fig. 6 is a flowchart illustrating a method for determining a degree of degradation of a battery according to a second embodiment of the present disclosure. The method of fig. 6 may be used to determine the degree of degradation of battery B in the presence of at least two peaks on the differential capacity curve.

Referring to fig. 1 to 4 and 6, in step S602, the control unit 120 acquires first sensing information indicating a voltage and a current of the battery B during a first period in which the battery B is charged with a first constant current from the sensing unit 110.

In step S604, the control unit 120 acquires second sensing information indicating the voltage and current of the battery B during a second period in which the battery B is discharged at a second constant current from the sensing unit 110.

In step S612, the control unit 120 determines a first differential capacity curve of the battery B based on the first sensing information. For example, the first differential capacity curve may be the differential capacity curve 401 of fig. 4.

In step S614, the control unit 120 determines a second differential capacity curve of the battery B based on the second sensing information. For example, the second differential capacity curve may be the differential capacity curve 402 of fig. 4.

In step S622, the control unit 120 detects first to nth charging characteristic points from the first differential capacity curve. n is a natural number of 2 or more, and is a predetermined value indicating a number equal to or less than the total number of peaks located on the first differential capacity curve. When i is 1 to n, the ith charging feature point may be a peak located in the ith order among the first to nth charging feature points, based on the remaining capacity.

In step S624, the control unit 120 detects the first to nth discharge characteristic points from the second differential capacity curve. Based on the remaining capacity, the ith discharge characteristic point may be a peak located in the ith order among the first to nth discharge characteristic points.

In step S630, the control unit 120 determines the degree of deterioration of the battery B based on the first to nth dominant differences. When i is 1 to n, the ith main difference value may be an absolute value of a difference between the ith charging characteristic value and the ith discharging characteristic value. The ith charging characteristic value is a voltage value of the ith charging characteristic point, and the ith discharging characteristic value is a voltage value of the ith discharging characteristic point. Subsequently, the control unit 120 determines a first degradation factor from the first to nth dominant differences. The control unit 120 may determine the first degradation factor using the following equation 1.

[ equation 1]

In equation 1, Δ V_iIs the ith main difference value, V_{CD_i}Is the ith charging characteristic value, V_{DD_i}Is the ith discharge characteristic value, alpha_iIs the ith predetermined weight, F_degIs the first degradation factor. Alpha is alpha_iMay be a preset value based on an increase in the ith charging characteristic value and a decrease in the ith discharging characteristic value with the deterioration of battery B. The increase in the ith charging characteristic value may be a ratio of the ith charging characteristic value to the ith initial charging characteristic value. The decrease in the ith discharge characteristic value may be a ratio of the ith discharge characteristic value to the ith initial discharge characteristic value.

For example, when n is 2, the above formula 1 may be expressed as the following formula 2.

[ formula 2]

The control unit 120 determines the degree of degradation of the battery B from the second data table, which records the first degradation factor F determined in step S630, using the first degradation factor as an index_degAnd the degree of deterioration.

The second data table may be stored in the storage unit 130. As the hysteresis characteristic of battery B becomes stronger, each of the first to nth principal difference values tends to increase. Thus, in the second data table, a larger first degradation factor may be associated with a higher degree of degradation.

Fig. 7 is a flowchart illustrating a method for determining degradation of a battery according to a third embodiment of the present disclosure. The method of fig. 7 may be used to determine the degree of degradation of battery B in the presence of at least one peak on the differential capacity curve.

Referring to fig. 1 to 4 and 7, in step S702, the control unit 120 acquires first sensing information of the voltage and current of the battery B during a first period in which the battery B is charged with a first constant current from the sensing unit 110.

In step S704, the control unit 120 acquires second sensing information indicating the voltage and current of the battery B during a second period in which the battery B is discharged at a second constant current from the sensing unit 110.

In step S712, the control unit 120 determines a first differential capacity curve of the battery B based on the first sensing information. For example, the first differential capacity curve may be the differential capacity curve 401 of fig. 4.

In step S714, the control unit 120 determines a second differential capacity curve of the battery B based on the second sensing information. For example, the second differential capacity curve may be the differential capacity curve 402 of fig. 4.

In step S722, the control unit 120 detects a charging characteristic point (e.g., P) from the first differential capacity curve_{CD_2}). Characteristic point of charge (e.g., P)_{CD_2}) May be peaks positioned in a predetermined order based on the remaining capacity among all peaks of the first differential capacity curve.

In step S724, the control unit 120 detects a discharge characteristic point (e.g., P) from the second differential capacity curve_{DD_2}). Discharge characteristic point (e.g., P)_{DD_2}) May be a peak positioned in a predetermined order based on the remaining capacity among all peaks of the second differential capacity curve.

In step S730, control unit 120 determines the degree of degradation of battery B based on a first sub-difference value, which is a charging characteristic value (e.g., V), and a second sub-difference value_{CD_2}) And an initial charge characteristic value (e.g., V)_{CI_2}) Absolute value of the difference therebetween (e.g., | V)_{CD_2}-V_{CI_2}|), the second sub-difference value is a discharge characteristic value (e.g., V)_{DD_2}) With an initial discharge characteristic (e.g. V)_{DI_2}) Absolute value of the difference therebetween (e.g., | V)_{DD_2}-V_{DI_2}│)。

InitialCharacteristic value of charge (e.g. V)_{CI_2}) May be peaks (e.g., P) positioned in a predetermined order on the differential capacity curve 301_{CI_2}) The voltage value of (2). Initial discharge characteristic value (e.g., V)_{DI_2}) May be peaks (e.g., P) positioned in a predetermined order on the differential capacity curve 302_{DI_2}) The voltage value of (2).

Characteristic value of charge (e.g. V)_{CD_2}) Is the voltage value (e.g. V) of the charging characteristic point_{CD_2}) And a discharge characteristic value (e.g., V)_{DD_2}) Is the voltage value (e.g. V) of the discharge characteristic point_{DD_2}). The control unit 120 may determine a sum of a product of the first sub difference value and the first transform coefficient and a product of the second sub difference value and the second transform coefficient as the second degradation factor. The first transform coefficient and the second transform coefficient may be values for adjusting the relative magnitude between the first sub-difference value and the second sub-difference value, because the first sub-difference value and the second sub-difference value may be different from each other when the degree of deterioration of battery B is the same. The first transform coefficient may be a preset positive number based on a correlation between the degree of deterioration of battery B and the first sub-difference value. The second transform coefficient may be a preset positive number based on a correlation between the degree of deterioration of battery B and the second sub-difference value.

The control unit 120 determines the degree of degradation of the battery B from a third data table that records the correlation between the second degradation factor determined in step S730 and the degree of degradation, using the second degradation factor as an index.

The third data table may be stored in the storage unit 130. As the hysteresis characteristic of battery B becomes stronger, the first sub-difference value and the second sub-difference value tend to increase at different rates. Therefore, in the third data table, a larger second deterioration factor is associated with a higher degree of deterioration.

When the first sub-difference value (e.g., -V)_{CD_2}-V_{CI_2}| and a second sub-difference value (e.g., | V)_{DD_2}-V_{DI_2}|) exceeds a predetermined range, the control unit 120 may determine that the battery B is abnormal. In this case, control unit 120 may output a message for notifying abnormality of battery B to the user using interface unit 140 instead of determining the degree of deterioration of battery B。

When determining the degree of degradation of the battery B according to at least one of the first to third embodiments, the control unit 120 may output a message for notifying the degree of degradation of the battery to the user using the interface unit 140.

The embodiments of the present disclosure described above are not only realized by the apparatuses and methods, but also realized by a program that realizes functions corresponding to the configuration of the embodiments of the present disclosure or a recording medium on which the program is recorded, and those skilled in the art can easily realize such realization from the disclosure of the foregoing embodiments.

Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations can be made within the technical aspects of the present disclosure and the equivalent scope of the appended claims.

Additionally, since many substitutions, modifications and variations may be made to the present disclosure by those skilled in the art without departing from the technical aspects of the present disclosure, the present disclosure is not limited to the foregoing embodiments and drawings, and some or all of the embodiments may be selectively combined to make various modifications to the present disclosure.