Apparatus and method for estimating state of secondary battery

Abstract

The invention relates to an apparatus and a method for estimating a state of a secondary battery. An apparatus according to an embodiment of the present disclosure includes: a charging unit electrically connected to both terminals of a secondary battery to charge the secondary battery; a voltage measuring unit electrically connected to both terminals of the secondary battery to measure a voltage across both terminals of the secondary battery; a time measuring unit configured to receive a voltage value of the secondary battery from the voltage measuring unit, and measure a charging time of the secondary battery corresponding to a voltage range multiple times in a predefined voltage range during charging of the secondary battery; and a control unit configured to transmit and receive electrical signals to and from the charging unit, the voltage measurement unit, and the time measurement unit, calculate a ratio of a first charging time and a second charging time sequentially measured by the time measurement unit at time intervals, and estimates the state of the secondary battery.

Description

[0001] This application is a divisional application of the Chinese invention patent application “Device and method for estimating the state of a secondary battery”, which entered the Chinese national phase on December 31, 2019, with PCT application number PCT / KR2019 / 001106, international application date January 25, 2019, and Chinese application number 201980003371.6. Technical Field

[0002] This application claims priority from Korean Patent Application No. 10-2018-0016387 filed in Korea on February 9, 2018, the disclosure of which is incorporated herein by reference.

[0003] The present disclosure relates to an apparatus and method for estimating a state of a secondary battery, and more particularly, to a secondary battery state estimation apparatus and method for effectively estimating the life span or degradation of a secondary battery as the secondary battery ages. Background Art

[0004] Currently, the demand for portable electronic products such as laptop computers, cameras, and mobile phones is rapidly increasing, and with the intense development of electric vehicles, batteries for energy storage devices, robots, and satellites, many studies are being conducted on high-performance secondary batteries that can be repeatedly recharged.

[0005] Currently, commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc., and among them, lithium secondary batteries have very little or no memory effect, and therefore compared with nickel-based secondary batteries, they are gaining more attention due to their advantages of free charging and discharging, extremely low self-discharge rate and high energy density.

[0006] Lithium secondary batteries mainly use lithium-based oxides and carbon materials as positive electrode active materials and negative electrode active materials, respectively. Lithium secondary batteries include: an electrode assembly, which includes a positive electrode plate and a negative electrode plate coated with a positive electrode active material and a negative electrode active material, respectively, with a separator interposed therebetween; and a packaging material, that is, a battery case, which is fully sealed to receive the electrode assembly together with an electrolyte solution.

[0007] Generally, lithium secondary batteries can be classified into can-type secondary batteries in which an electrode assembly is embedded in a metal can and pouch-type secondary batteries in which an electrode assembly is embedded in a pouch of an aluminum laminate according to the shape of the packaging material. These secondary batteries are generally manufactured by receiving the electrode assembly in the packaging material, and in this state, injecting an electrolyte solution and sealing the packaging material.

[0008] Recently, as the application range of secondary batteries expands, secondary batteries are widely used not only in small portable devices including smartphones but also in medium and large devices such as electric vehicles including hybrid electric vehicles or energy storage systems.

[0009] In the case of a secondary battery, as the usage period increases, the performance deteriorates compared to the initial state. In addition, the performance degradation estimation of the secondary battery is called the state of health (SOH) estimation of the secondary battery, and the SOH of the secondary battery is an important factor in determining when to replace the secondary battery.

[0010] In addition, the degradation level is different in each secondary battery depending on the environment in which the secondary battery is manufactured and used. In addition, in the case of a battery pack including a plurality of secondary batteries, the life of each secondary battery must be accurately estimated based on the degradation level of each secondary battery. Generally, a battery management system (BMS) is required to accurately estimate the life of each secondary battery provided in the battery pack, and based on this, efficiently operate the battery pack. Summary of the invention

[0011] Technical issues

[0012] The present disclosure is designed in the context of the related art, and thus, the present disclosure relates to an improved secondary battery state estimation apparatus and method for effectively estimating the lifetime or degradation of a secondary battery as the secondary battery ages.

[0013] These and other objects and advantages of the present disclosure can be understood from the following detailed description and will be clear from the embodiments of the present disclosure. In addition, it should be easily understood that the objects and advantages of the present disclosure are achieved by the means and combinations thereof set forth in the appended claims.

[0014] Technical Solutions

[0015] In order to achieve the above-mentioned objectives, an apparatus for estimating the state of a secondary battery according to an embodiment of the present disclosure includes: a charging unit, which is electrically connected to two terminals of the secondary battery to charge the secondary battery; a voltage measuring unit, which is electrically connected to the two terminals of the secondary battery to measure the voltage across the two terminals of the secondary battery; a time measurement unit, which is configured to receive a voltage value of the secondary battery from the voltage measurement unit, and measure the charging time of the secondary battery corresponding to the voltage range multiple times in a predefined voltage range during charging of the secondary battery; and a control unit, which is configured to send electrical signals to the charging unit, the voltage measurement unit and the time measurement unit, and receive electrical signals from the charging unit, the voltage measurement unit and the time measurement unit, calculate the ratio of a first charging time to a second charging time sequentially measured by the time measurement unit at time intervals, and estimate the state of the secondary battery.

[0016] Furthermore, the voltage measuring unit may measure a voltage across two terminals of the secondary battery when a charging current is continuously supplied from the charging unit to the secondary battery.

[0017] Furthermore, the apparatus for estimating a state of a secondary battery according to an embodiment of the present disclosure may further include a memory unit configured to pre-store a degradation level of the secondary battery corresponding to a ratio of the second charging time to the first charging time.

[0018] In addition, the apparatus for estimating the state of a secondary battery according to an embodiment of the present disclosure may also include an alarm unit configured to receive an electrical signal from the control unit and send an alarm signal including information associated with a degradation level of the secondary battery to an external device based on the signal received from the control unit.

[0019] Furthermore, the voltage range may include a first voltage range in which a constant charging current is maintained and a second voltage range in which a constant charging voltage is maintained, and the time measurement unit may be configured to measure a charging time of the secondary battery corresponding to each of the first voltage range and the second voltage range.

[0020] Furthermore, the control unit may be configured to calculate a ratio of a plurality of charging times measured at time intervals in the first voltage range or a plurality of charging times measured at time intervals in the second voltage range.

[0021] Furthermore, the control unit may be configured to set the charging time at a product sales point of the secondary battery as a first charging time, set the charging time measured at a time interval from the first charging time as a second charging time, and calculate a ratio of the second charging time to the first charging time.

[0022] Furthermore, the control unit may be configured to transmit a replacement signal of the secondary battery when a ratio of the second charging time to the first charging time is a predetermined value or less.

[0023] Furthermore, a battery pack according to an embodiment of the present disclosure includes the apparatus for estimating a state of a secondary battery according to the present disclosure.

[0024] In addition, in order to achieve the above-mentioned objectives, a method for estimating the state of a secondary battery according to an embodiment of the present disclosure includes: charging the secondary battery; measuring the voltage across two terminals of the secondary battery; receiving the voltage value of the secondary battery, and measuring the charging time of the secondary battery corresponding to the voltage range multiple times in a predefined voltage range during the charging of the secondary battery; and, for a first charging time and a second charging time measured sequentially at time intervals, calculating the ratio of the second charging time to the first charging time, and estimating the state of the secondary battery.

[0025] Beneficial effects

[0026] According to aspects of the present disclosure, an apparatus for estimating a state of a secondary battery measures a charging time of a secondary battery and estimates a degradation level of the secondary battery using a ratio between a plurality of charging times, thereby estimating the degradation level of the secondary battery in an easy and simple manner.

[0027] Specifically, in contrast to the prior art that considers absolute charging time, the device for estimating the state of a secondary battery according to aspects of the present disclosure may use a ratio of charging time. The prior art that considers absolute charging time has difficulty accurately estimating the state of a secondary battery due to process deviations in the manufacture of the secondary battery. Therefore, the device for estimating the state of a secondary battery according to the present disclosure may use a ratio of charging time to accurately estimate the degradation level of the secondary battery.

[0028] The present disclosure may have various other effects, and these and other effects of the present disclosure can be understood through the specific implementation and will be apparent from the embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the following detailed description, serve to provide a further understanding of the technical aspects of the present disclosure, and therefore the present disclosure should not be construed as being limited to the accompanying drawings.

[0030] Figure 1 is a schematic diagram illustrating a functional configuration of an apparatus for estimating a state of a secondary battery and connection with a secondary battery according to an embodiment of the present disclosure.

[0031] Figure 2 A change in charging time based on a degradation level of a secondary battery connected to the apparatus for estimating a state of a secondary battery according to an embodiment of the present disclosure is shown.

[0032] Figure 3 A change in charging time based on a degradation level of a secondary battery connected to an apparatus for estimating a state of a secondary battery according to another embodiment of the present disclosure is shown.

[0033] Figure 4 A change in charging time of a secondary battery and a change in a ratio of the charging time according to an embodiment of the present disclosure are shown.

[0034] Figure 5 is a schematic flowchart illustrating a method for estimating a state of a secondary battery according to an embodiment of the present disclosure.

[0035] Figure 6 is a schematic flowchart illustrating a method for estimating a state of a secondary battery according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] 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 this specification and the appended claims should not be interpreted as limited to the general dictionary meaning, but should be interpreted based on the meaning and concept corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation.

[0037] Therefore, the embodiments described herein and the illustrations shown in the accompanying 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. Therefore, it should be understood that the present disclosure may have various other equivalents and modifications when the present application is filed.

[0038] Furthermore, in describing the present disclosure, when a specific detailed description of related known elements or functions is deemed to obscure the key subject matter of the present disclosure, the detailed description will be omitted herein.

[0039] Unless the context clearly indicates otherwise, it should be understood that the term "comprise" or "include" when used in this specification specifies the presence of the elements recited, but does not exclude the presence or addition of one or more elements. In addition, the term "control unit" as used herein means a processing unit of at least one function or operation, and this can be implemented by hardware or software independently or in combination.

[0040] Additionally, throughout this 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.

[0041] In this specification, a secondary battery refers to a physically separable independent secondary battery including a negative electrode terminal and a positive electrode terminal. For example, a pouch-type lithium polymer cell may be regarded as a secondary battery.

[0042] Figure 1 is a schematic diagram illustrating a functional configuration of an apparatus for estimating a state of a secondary battery and connection with a secondary battery according to an embodiment of the present disclosure.

[0043] Reference Figure 1 , an apparatus 1 for estimating a state of a secondary battery according to the present disclosure includes a charging unit 100 , a voltage measuring unit 200 , a time measuring unit 300 , and a control unit 400 .

[0044] The charging unit 100 may be electrically connected to both terminals of the secondary battery 10. Specifically, the charging unit 100 according to the present disclosure may be electrically connected to both terminals of the secondary battery 10 to supply charging power to the secondary battery 10. Figure 1 As shown in the configuration of , the charging unit 100 may be electrically connected to each of the positive electrode terminal and the negative electrode terminal of the secondary battery 10 to supply charging power to the secondary battery 10 .

[0045] The charging unit 100 may charge the secondary battery 10. Specifically, when the voltage of the secondary battery 10 corresponds to a predefined voltage, the charging unit 100 may start charging the secondary battery 10. In addition, when the voltage of the secondary battery 10 corresponds to a predefined voltage, the charging unit 100 may terminate the charging of the secondary battery 10. In more detail, the charging unit 100 may charge the secondary battery 10 from a predetermined charging start voltage until the voltage of the secondary battery 10 reaches a predetermined charging end voltage.

[0046] The charging unit 100 according to an embodiment of the present disclosure may be provided in a hybrid electric vehicle or an electric vehicle, and may be supplied with charging power from the hybrid electric vehicle or the electric vehicle.

[0047] The charging unit 100 according to another embodiment of the present disclosure may be provided in a secondary battery testing apparatus, and may be supplied with charging power from an external power source.

[0048] The voltage measuring unit 200 may be electrically connected to both terminals of the secondary battery 10. In addition, the voltage measuring unit 200 according to the present disclosure may measure a voltage across both terminals of the secondary battery 10.

[0049] Preferably, the voltage measuring unit 200 according to the present disclosure may measure the voltage across the two terminals of the secondary battery 10 when the charging / discharging current continuously flows into or out of the secondary battery 10. Specifically, the voltage measuring unit 200 may measure the voltage across the two terminals of the secondary battery 10 when the charging current is continuously supplied from the charging unit 100 to the secondary battery 10. For example, the voltage measuring unit 200 may measure the voltage across the two terminals of the secondary battery 10 when a hybrid electric vehicle or an electric vehicle is traveling.

[0050] The time measurement unit 300 may measure the charging time of the secondary battery 10. Specifically, the time measurement unit 300 may sequentially measure the charging time of the secondary battery 10 a plurality of times at time intervals. In addition, the time measurement unit 300 may be electrically connected to the voltage measurement unit 200 to transmit and receive electrical signals to and from the voltage measurement unit 200. Here, the time measurement unit 300 may receive the voltage value of the secondary battery 10 from the voltage measurement unit 200.

[0051] In addition, the time measurement unit 300 may measure the charging time of the secondary battery 10 in a predefined voltage range during the charging of the secondary battery 10. In more detail, during the charging of the secondary battery 10, in a predefined voltage range between a charging start voltage and a charging end voltage, the time measurement unit 300 may be configured to measure the charging time of the secondary battery 10 corresponding to the voltage range a plurality of times.

[0052] The control unit 400 may be configured to estimate the state of the secondary battery 10. In addition, the control unit 400 may be electrically connected to each of the charging unit 100, the voltage measuring unit 200, and the time measuring unit 300 to transmit and receive electrical signals to and from the charging unit 100, the voltage measuring unit 200, and the time measuring unit 300.

[0053] In addition, the control unit 400 may calculate a ratio of charging times. Specifically, the control unit 400 may calculate a ratio of a plurality of charging times sequentially measured at time intervals. In more detail, the control unit 400 may calculate a ratio of a first charging time to a second charging time sequentially measured at time intervals by the time measurement unit 300. To this end, the control unit 400 may receive a plurality of charging times from the time measurement unit 300. In more detail, the control unit 400 may receive a first charging time and a second charging time from the time measurement unit 300.

[0054] The control unit 400 may use the calculated ratio of the charging time to estimate the state of the secondary battery 10. A detailed description thereof will be provided below. Meanwhile, in order to perform the above operations, the control unit 400 may selectively include a processor, an application specific integrated circuit (ASIC), a chipset, a logic circuit, a register, a communication modem and / or a data processing device known in the art.

[0055] Preferably, the apparatus 1 for estimating a state of a secondary battery according to an embodiment of the present disclosure may further include a memory unit 500 .

[0056] The memory unit 500 may pre-store the degradation level of the secondary battery 10. Specifically, the memory unit 500 may pre-store the degradation level of the secondary battery 10 corresponding to the ratio of the charging time. In more detail, the memory unit 500 may pre-store the degradation level of the secondary battery 10 corresponding to the ratio of the second charging time to the first charging time sequentially measured at time intervals.

[0057] In addition, the memory unit 500 is not limited to a specific type, and includes any type of storage medium that can record and erase information. For example, the memory unit 500 can be a RAM, a ROM, a register, a hard disk, an optical recording medium, or a magnetic recording medium. In addition, the memory unit 500 can be electrically connected to the control unit 400 through, for example, a data bus to allow the control unit 400 to access. In addition, the memory unit 500 can store and / or update and / or erase and / or send programs including various control logics executed by the control unit 400 and / or data generated when the control logic is executed.

[0058] Furthermore, preferably, the apparatus 1 for estimating a state of a secondary battery according to an embodiment of the present disclosure may further include an alarm unit 600 .

[0059] The alarm unit 600 may send an alarm signal. For example, the alarm unit 600 may send the alarm signal to an external device or a vehicle. In addition, the alarm unit 600 may receive an electrical signal from the control unit 400. Here, the control unit 400 may send a control signal to the alarm unit 600 to allow the alarm unit 600 to send the alarm signal. In more detail, the alarm unit 600 may send an alarm signal including information associated with the degradation level of the secondary battery 10 to the external device based on the signal received from the control unit 400. For example, the alarm unit 600 may send a replacement signal including information about the secondary battery 10 that has degraded and needs to be replaced.

[0060] Figure 2 A change in charging time based on a degradation level of a secondary battery connected to the apparatus for estimating a state of a secondary battery according to an embodiment of the present disclosure is shown.

[0061] Reference Figure 2 , the secondary battery 10 connected to the apparatus 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure can be charged within a preset voltage range. That is, when the voltage of the secondary battery 10 corresponds to the preset charge start voltage, the charging unit 100 according to the present disclosure can charge the secondary battery 10. For example, Figure 2 As shown in the graph of , when the voltage of the secondary battery 10 corresponds to V1, the charging unit 100 may charge the secondary battery 10.

[0062] In addition, when the voltage of the secondary battery 10 reaches a preset charge end voltage, the charging unit 100 may terminate the charging of the secondary battery 10. Figure 2 As shown in the graph of , when the voltage of the secondary battery 10 reaches V2, the charging unit 100 may terminate the charging of the secondary battery 10.

[0063] The apparatus 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure can estimate the state of the secondary battery 10 at time intervals. That is, the apparatus 1 for estimating the state of a secondary battery can sequentially measure the charging time of the secondary battery 10 at time intervals and estimate the state of the secondary battery 10 using the measured charging time.

[0064] In addition, the time measurement unit 300 may measure the charging time corresponding to the predefined voltage range between the charging start voltage and the charging end voltage multiple times. Figure 2 As shown in the curve diagram of , the time measurement unit 300 can measure the charging time multiple times in the voltage range between V1 and V2. Figure 2In the embodiment of the present invention, the time measurement unit 300 may measure a plurality of charging times corresponding to a1, b1, and c1. For example, the control unit 400 may receive a plurality of charging times from the time measurement unit 300 and estimate the degradation level of the secondary battery 10 according to the charging time. For example, as the charging time is shortened, the degradation level of the secondary battery 10 may increase. That is, Figure 2 The degradation level of the secondary battery 10 shown in the graph of gradually increases in the order of c1, b1, and a1. That is, when the charging time is measured at time intervals for one secondary battery 10, the charging time decreases in the order of c1, b1, and a1.

[0065] The secondary battery 10 connected to the device 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure may be charged in a preset voltage range. Here, the voltage range may include a first voltage range in which a constant charging current is maintained and a second voltage range in which a constant charging voltage is maintained. Here, the time measurement unit 300 may measure the charging time of the secondary battery 10 corresponding to each of the first voltage range and the second voltage range.

[0066] Since the internal resistance increases as the secondary battery 10 ages, there is a decrease in the charging time of the first voltage range in which a constant charging current is maintained, and an increase in the charging time of the second voltage range in which a constant charging voltage is maintained as the secondary battery 10 deteriorates. However, as the secondary battery 10 deteriorates, the total charging time including the first voltage range and the second voltage range is shortened.

[0067] For example, in Figure 2 In the voltage-time curve diagram shown, when the charging time of the voltage range V1 to V2 corresponds to a1, the range of the charging time from 0 to a1 may correspond to the first voltage range in which the constant charging current is maintained. In addition, the range of the charging time from a2 may correspond to the second voltage range in which the constant charging voltage is maintained. For example, as the degradation level of the secondary battery 10 increases, the charging time of the first voltage range gradually decreases in the order of c1, b1, and a1, and the charging time of the second voltage range gradually increases in the order of c2, b2, and a2. However, the total charging time including the first voltage range and the second voltage range decreases in the order of c1+c2, b1+b2, and a1+a2.

[0068] Preferably, the control unit 400 according to an embodiment of the present disclosure may calculate a ratio of a plurality of charging times measured at time intervals in a predefined voltage range. In more detail, the control unit 400 may calculate a ratio of a plurality of charging times measured at time intervals in a first voltage range. Alternatively, the control unit 400 may calculate a ratio of a plurality of charging times measured at time intervals in a second voltage range. For example, Figure 2In the embodiment of the present invention, the control unit 400 may calculate the ratio of a1, b1 and c1 measured at time intervals in the first voltage range. In addition, the control unit 400 may calculate the ratio of a2, b2 and c2 measured at time intervals in the second voltage range.

[0069] In addition, preferably, the control unit 400 according to an embodiment of the present disclosure may set the charging time at the product sales point of the secondary battery 10 as the first charging time, set the charging time measured at time intervals from the first charging time as the second charging time, and calculate the ratio of the second charging time to the first charging time. Here, the charging time at the product sales point of the secondary battery 10 may represent the charging time of the secondary battery 10 at the beginning of life (BOL). For example, Figure 2 In the embodiment of the present invention, the control unit 400 may set c1 as the first charging time and b1 or a1 as the second charging time. In addition, the control unit 400 may calculate the ratio of b1 to c1 or the ratio of a1 to c1. Alternatively, the control unit 400 may set c2 as the first charging time and b2 or a2 as the second charging time. In addition, the control unit 400 may calculate the ratio of b2 to c2 or the ratio of a2 to c2.

[0070] According to this configuration of the present disclosure, the apparatus for estimating the state of a secondary battery according to the present disclosure can quickly estimate the state of the secondary battery by comparing the charging times of the preset voltage ranges.

[0071] Furthermore, the apparatus 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure does not consistently apply the first charging time as a specific value, and may measure the charging time at the initial state (the state at the product sales point) of each secondary battery 10, and determine the first charging time of each secondary battery 10. That is, because the initial state (the state at the product sales point) of the secondary battery 10 may be different due to resistance deviation or capacitance deviation, the apparatus 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure may estimate the current state of each secondary battery 10 more accurately than when a specific value is consistently applied as the first charging time of the secondary battery 10.

[0072] Figure 3 A change in charging time based on a degradation level of a secondary battery connected to an apparatus for estimating a state of a secondary battery according to another embodiment of the present disclosure is shown.

[0073] Reference Figure 3 , the secondary battery 10 connected to the device 1 for estimating the state of a secondary battery according to the present disclosure can be charged and discharged within a preset voltage range. For example, when a hybrid electric vehicle or an electric vehicle is traveling, the secondary battery 10 connected to the device 1 for estimating the state of a secondary battery can be charged and discharged.

[0074] Figure 3 The graph shown shows two measurement times measured at time intervals when the secondary battery 10 is charged and discharged in the preset voltage range V1 to V2. Here, it is assumed that the measurement time t1 and the measurement time t2 are measured at a considerable time interval. For example, there may be a time interval of one year between the measurement time t1 and the measurement time t2.

[0075] Here, the time measurement unit 300 may measure the charging time of the secondary battery 10 in a voltage range Va to Vb corresponding to a predefined voltage range. More specifically, in the voltage range Va to Vb, the time measurement unit 30 may measure t1 and measure t2 at a time interval from t1. In this configuration, the control unit 400 may calculate a ratio of t2 to t1 and estimate the degradation level of the secondary battery 10 using the calculated ratio. That is, the control unit 400 may estimate the degradation level of the secondary battery 10 according to the ratio of t1 to t2 based on the degradation level pre-stored in the memory unit 500.

[0076] Figure 4 A change in charging time of a secondary battery and a change in a ratio of the charging time according to an embodiment of the present disclosure are shown.

[0077] like Figure 4 As shown, the memory unit 500 according to an embodiment of the present disclosure may pre-store the degradation level of the secondary battery 10 corresponding to the ratio of the charging time. In this example, the control unit 500 may store a plurality of charging times received from the time measurement unit 300.

[0078] Reference Figure 1 and Figure 4 , the memory unit 500 may store the charging time corresponding to the voltage range and the ratio of the charging time. For example, the BOL charging time of the secondary battery 10 may be 4,611s in the first range and 263s in the second range. Here, the charging time of the total range including the first range and the second range may be 4,874s. In addition, the charging time of the secondary battery 10 after two years of use may be 3,349s in the first range and 376s in the second range. Here, the charging time of the total range including the first range and the second range may be 3,725s. In addition, the charging time of the secondary battery 10 after four years of use may be 3,050s in the first range and 440s in the second range. Here, the charging time of the total range including the first range and the second range may be 3,490s.

[0079] The control unit 400 may receive the charging time of the voltage range from the memory unit 500 and calculate the ratio of the charging time. Figure 4In the embodiment of , when the BOL charging time of the secondary battery 10 is set to 100%, the ratio of the charging time of the secondary battery 10 after two years of use to the BOL charging time of the secondary battery 10 may be 76.43%, and the ratio of the charging time of the secondary battery 10 after four years of use to the BOL charging time of the secondary battery 10 may be 71.60%. The control unit 400 may calculate the ratio of the charging time of the first range and the ratio of the charging time of the second range. Alternatively, the control unit 400 may calculate the ratio of the charging time of the total range.

[0080] Preferably, the control unit 400 may determine whether the secondary battery 10 needs to be replaced. Specifically, when the ratio of the charging time is a predetermined value or less, the control unit 400 may determine that the secondary battery 10 needs to be replaced. In more detail, when the ratio of the second charging time to the first charging time is a predetermined value or less, the control unit 400 may be configured to send a replacement signal of the secondary battery 10. For example, when the ratio of the charging time of the secondary battery 10 to the BOL charging time corresponds to 75%, the control unit 400 may determine that the secondary battery 10 needs to be replaced.

[0081] Here, the predetermined value may be determined differently for each secondary battery 10. That is, the predetermined value may be a value independently set for each secondary battery 10 based on the initial state of the secondary battery 10. For example, because the predetermined value is different for each secondary battery 10, even if the ratio of the second charging time to the first charging time of the first secondary battery is equal to the ratio of the second charging time to the first charging time of the second secondary battery, a replacement signal only for the first secondary battery may be transmitted.

[0082] As a specific example, in the case of an emergency call application, a specific power must be supplied to prepare for an emergency situation. Therefore, the secondary battery 10 used in the emergency call application should always have a discharge capacity sufficient to supply a specific power. However, because the initial state may be different for each secondary battery 10 depending on the initial capacity and resistance deviation of the secondary battery 10, the predetermined value may be determined for each secondary battery 10 based on the correlation between the discharge capacity (remaining capacity) and the charging time of each secondary battery 10. For example, the predetermined value of the first secondary battery may be 75%, the predetermined value of the second secondary battery may be 78%, and the predetermined value of the third secondary battery may be 76%. In this example, if it is assumed that the ratio of the second charging time to the first charging time of the first to third secondary batteries is all 76%, then the control unit 400 may determine that the second secondary battery and the third secondary battery need to be replaced, and send a replacement signal for the second secondary battery and the third secondary battery. That is, the apparatus 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure independently determines a reference ratio (predetermined value) for determining whether the secondary battery 10 needs to be replaced based on the initial state of each secondary battery 10 to more precisely and accurately measure the state of each secondary battery 10 .

[0083] In addition, the device 1 for estimating the state of a secondary battery according to an embodiment of the present disclosure uses the absolute time and the ratio of the charging time to determine the state of each secondary battery 10. That is, because the device 1 for estimating the state of a secondary battery uses the ratio of the charging time of each secondary battery 10, the state of each secondary battery 10 can be determined regardless of the difference in resistance or capacitance between the secondary batteries 10. For example, when the state of the secondary battery 10 is consistently determined according to the absolute charging time of the secondary battery 10, the degradation level of each secondary battery 10 cannot be accurately measured because the difference in resistance or capacitance between the secondary batteries 10 is not considered. That is, even if the charging time is the same, the degradation level may be different depending on the resistance or capacitance of the secondary battery 10. Therefore, when only the absolute charging time is considered, it is impossible to accurately measure the state of the secondary battery 10, and therefore, the device 1 for estimating the state of the secondary battery can measure the state of each secondary battery 10 more accurately than when only the absolute charging time is used.

[0084] The device 1 for estimating the state of a secondary battery according to the present disclosure may be provided in the battery pack itself. That is, the battery pack according to the present disclosure may include the above-mentioned device for estimating the state of a secondary battery according to the present disclosure. Here, the battery pack may include a plurality of secondary batteries, a device for estimating the state of a secondary battery, electrical components (BMS, relays, fuses, etc.), and a housing.

[0085] Figure 5is a schematic flow chart showing a method for estimating a state of a secondary battery according to an embodiment of the present disclosure. Figure 5 In the embodiment, a subject that performs each step may be each component of the aforementioned apparatus 1 for estimating a state of a secondary battery according to the present disclosure.

[0086] like Figure 1 and Figure 5 As shown, according to the method for estimating the state of a secondary battery of the present disclosure, in step S100 , the charging unit 100 charges the secondary battery 10 .

[0087] Subsequently, in step S110 , the voltage measurement unit 200 measures the voltage across both terminals of the secondary battery 10 .

[0088] Subsequently, in step S120 , the time measurement unit 300 receives the voltage value of the secondary battery 10 , and measures the charging time of the secondary battery 10 corresponding to the voltage range a plurality of times during charging of the secondary battery 10 in a predefined voltage range.

[0089] Subsequently, the control unit 400 calculates a ratio of the second charging time to the first charging time with respect to the first charging time and the second charging time sequentially measured at time intervals, and estimates the state of the secondary battery 10 in step S130 .

[0090] Preferably, in step S110 , the voltage measuring unit 200 may measure voltages across both terminals of the secondary battery 10 when the charging current is continuously supplied from the charging unit 100 to the secondary battery 10 .

[0091] Preferably, in step S130, the control unit 400 sets the charging time at the product sales point of the secondary battery 10 as the first charging time, sets the charging time measured at the time interval from the first charging time as the second charging time, and calculates the ratio of the second charging time to the first charging time.

[0092] Figure 6 is a schematic flow chart showing a method for estimating a state of a secondary battery according to another embodiment of the present disclosure. Figure 6 In the embodiment, the subject that performs each step may be each component of the aforementioned device 1 for estimating the state of a secondary battery according to the present disclosure. Figure 6 The charge start voltage (3.9 V), charge end voltage (4.1 V), and predetermined value (75%) transmitted by the replacement signal shown are only examples, and the method for estimating the state of a secondary battery according to an embodiment of the present disclosure is not limited to these values.

[0093] like Figure 1 and Figure 6As shown, according to the method for estimating the state of a secondary battery of the present disclosure, in step S200, the charging unit 400 may determine whether the voltage of the secondary battery 10 corresponds to the charge start voltage. Here, the charge start voltage may be 3.9V.

[0094] When the determination result of step S200 is "yes", in step S210, the control unit 400 may send a charge start command to the charging unit 100 to enable the charging unit 100 to charge the secondary battery 10. On the contrary, when the determination result of step S200 is "no", the control unit 400 may not charge the secondary battery 10.

[0095] Subsequently, in step S220, the time measurement unit 300 may record the charging time of the secondary battery 10. Specifically, the time measurement unit 300 may start recording the charging time when charging starts.

[0096] Subsequently, the control unit 400 may determine whether the voltage of the secondary battery 10 corresponds to a charge end voltage in step S230. Here, the charge end voltage may be 4.1V.

[0097] When the determination result of step S230 is "yes", in step S240, the control unit 400 may send a charge end command to the charging unit 100 so that the charging unit 100 can terminate the charging of the secondary battery 10. On the contrary, when the determination result of step S230 is "no", the control unit 400 may keep charging the secondary battery 10.

[0098] Subsequently, in step S250, the time measurement unit 300 may record the charging time of the secondary battery 10. Specifically, the time measurement unit 300 may terminate the recording of the charging time when the charging is finished.

[0099] Then, in step S260, the control unit 400 may calculate the ratio of the charging time. In this example, the control unit 400 may receive the charging time from the memory unit 500 or the time measurement unit 300.

[0100] Then, in step S270, the control unit 400 may determine whether the ratio of the charging time corresponds to the replacement time. For example, the control unit 400 may determine that it is time to replace when the ratio of the charging time is 75% or less.

[0101] When the determination result of step S270 is "yes", in step S280, the control unit 400 may transmit a replacement signal transmission command to the alarm unit 600. In addition, the alarm unit 600 may transmit the replacement signal based on the command received from the control unit 400. On the contrary, the determination result of step S270 is "no", the control unit 400 may return to step S200 to determine whether the voltage of the secondary battery 10 corresponds to the charge start voltage.

[0102] When the control logic is implemented in software, the control unit 400 may be implemented as a set of program modules. In this example, the program modules may be stored in a memory device and executed by a processor.

[0103] In addition, at least one of the various control logics of the control unit 400 can be combined, and the combined control logic is not limited to a specific type and includes any type that can be written in a computer-readable coding system and read and accessed by a computer. For example, the recording medium may include at least one selected from the group consisting of: ROM, RAM, register, CD-ROM, magnetic tape, hard disk, floppy disk, and optical data recording device. In addition, the coding system can be stored and executed in a computer connected via a network in a decentralized manner. In addition, the functional program, code, and segmentation for implementing the combined control logic can be easily inferred from a program in the technical field related to the present disclosure.

[0104] 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 is apparent to those skilled in the art that various modifications and changes may be made to the present disclosure within the technical aspects of the present disclosure and the equivalent scope of the appended claims.

[0105] Meanwhile, the term “unit” such as “memory unit” and “control unit” is used herein, but this means a logical component unit, and those skilled in the art understand that the term does not necessarily indicate components that can or should be physically separated from each other.

Claims

1. A device for estimating a state of a secondary battery, comprising: a charging unit electrically connected to two terminals of the secondary battery to charge the secondary battery; a voltage measuring unit electrically connected to the two terminals of the secondary battery to measure a voltage across the two terminals of the secondary battery; a time measurement unit configured to receive the voltage value of the secondary battery from the voltage measurement unit and measure the charging time of the secondary battery corresponding to the voltage range a plurality of times in a predefined voltage range during charging of the secondary battery; as well as A control unit configured to send and receive electrical signals to and from the charging unit, the voltage measuring unit, and the time measuring unit, set the charging time of the secondary battery at a product sales point as a first charging time, set the charging time measured at a time interval of the first charging time as a second charging time, calculate a ratio of the first charging time to the second charging time sequentially measured by the time measuring unit at time intervals, and estimate the state of the secondary battery.

2. The device for estimating the state of a secondary battery according to claim 1, wherein The voltage measurement unit measures a voltage across the two terminals of the secondary battery when a charging current is continuously supplied from the charging unit to the secondary battery.

3. The apparatus for estimating a state of a secondary battery according to claim 1, further comprising: A memory unit configured to pre-store a degradation level of the secondary battery corresponding to a ratio of the second charging time to the first charging time.

4. The apparatus for estimating a state of a secondary battery according to claim 1, further comprising: An alarm unit is configured to receive an electrical signal from the control unit and transmit an alarm signal including information associated with a degradation level of the secondary battery to an external device based on the signal received from the control unit.

5. The apparatus for estimating the state of a secondary battery according to claim 1, wherein The voltage range includes a first voltage range in which a constant charging current is maintained and a second voltage range in which a constant charging voltage is maintained, and The time measurement unit is configured to measure a charging time of the secondary battery corresponding to each of the first voltage range and the second voltage range.

6. The apparatus for estimating the state of a secondary battery according to claim 5, wherein: The control unit is configured to calculate a ratio of a plurality of charging times measured at time intervals in the first voltage range or a plurality of charging times measured at time intervals in the second voltage range.

7. The apparatus for estimating the state of a secondary battery according to claim 1, wherein The control unit is configured to transmit a replacement signal of the secondary battery when a ratio of the second charging time to the first charging time is a predetermined value or less.

8. A battery pack comprising the apparatus for estimating a state of a secondary battery according to any one of claims 1 to 7.

9. A method for estimating a state of a secondary battery, comprising: charging the secondary battery; measuring a voltage across two terminals of the secondary battery; receiving a voltage value of the secondary battery, and measuring a charging time of the secondary battery corresponding to the voltage range a plurality of times in a predefined voltage range during charging of the secondary battery; Setting the charging time of the secondary battery at a product sales point as a first charging time, and setting the charging time measured at a time interval of the first charging time as a second charging time; as well as With respect to the first charging time and the second charging time sequentially measured at time intervals, a ratio of the second charging time to the first charging time is calculated, and a state of the secondary battery is estimated.

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