Battery management system, battery management method, battery pack and electric vehicle

Abstract

A battery management system according to the present invention includes: a voltage sensor for generating a voltage signal indicating a battery voltage; a current sensor for generating a current signal indicating a current flowing through the battery; and a control unit for recording the battery's voltage and current history based on the voltage and current signals at predetermined time intervals while charging the battery at a constant current. The control unit determines a differential capacity curve indicating a corresponding relationship between the battery's voltage and differential capacity within a reference voltage range. When a main characteristic point is detected from the differential capacity curve, a controller compares a first characteristic voltage at the main characteristic point with a reference voltage and performs a first protection operation on the battery.

Description

Technical Field

[0001] The present disclosure relates to a battery protection technology. Background Art

[0002] Recently, demand for portable electronic products such as laptop computers, camcorders, and mobile phones has rapidly increased, and with the widespread development of electric vehicles, batteries for energy storage, robots, and satellites, much research is being conducted on high-performance batteries that can be repeatedly charged and discharged.

[0003] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc., and among them, lithium batteries have almost no memory effect. Therefore, due to the advantages of being able to be charged at any convenient time, having a very low self-discharge rate, and having a high energy density, they are receiving more and more attention than nickel-based batteries.

[0004] During battery charging or discharging, polarization occurs in the battery, and polarization causes overvoltage in the battery. Polarization depends on the resistance component (e.g., ohmic resistance, charge transfer resistance, diffusion resistance) that gradually increases as the battery degrades. Therefore, as the current rate during charging and discharging increases, the battery temperature decreases, and the battery deteriorates, the polarization becomes more severe, and as a result, it is well known that the magnitude of the overvoltage that occurs in the battery increases. When the battery is used in a potential polarized state, the battery deteriorates rapidly. Summary of the Invention

[0005] Technical issues

[0006] The inventors discovered that the phase change reactions occurring during battery charging are largely dependent on polarization which is positively correlated with the overvoltage of the battery.

[0007] The present disclosure is designed to solve the above-mentioned problems. Therefore, the present disclosure aims to provide a battery management system, a battery management method, a battery pack and an electric vehicle, which determine the differential capacity curve of a preset voltage range interval in which a single phase change reaction occurs during battery charging, and use the characteristic point detection results of the reference differential capacity curve to determine the polarization level.

[0008] The present disclosure also aims to provide a battery management system, a battery management method, a battery pack, and an electric vehicle, which perform different protection operations on a battery using a polarization level determined according to a characteristic point detection result with reference to a differential capacity curve.

[0009] These and other purposes and advantages of the present disclosure can be understood through the following description and will be apparent from the embodiments of the present disclosure.In addition, it will be easily understood that the purposes and advantages of the present disclosure can be achieved by means of the means set forth in the appended claims and their combinations.

[0010] Technical Solution

[0011] According to one aspect of the present disclosure, a battery management system includes: a voltage sensor configured to generate a voltage signal indicating the voltage of a battery; a current sensor configured to generate a current signal indicating the current flowing through the battery; and a control unit configured to record the voltage history and current history of the battery at predetermined time intervals based on the voltage signal and the current signal during constant current charging of the battery. The control unit is configured to determine, based on the voltage history and the current history, a differential capacity curve indicating a correlation between the voltage and differential capacity of the battery within a reference voltage range. The control unit is configured to perform a first protection operation on the battery by comparing a first characteristic voltage of the main characteristic point with a reference voltage when a main characteristic point is detected from the differential capacity curve.

[0012] The control unit may be configured to determine a maximum point detected for the first time from the differential capacity curve during constant-current charging of the battery as the main characteristic point.

[0013] The first protection operation may include reducing the cutoff voltage of the constant current charging by a compensation voltage corresponding to the voltage difference between the first characteristic voltage and the reference voltage. The lower limit of the cutoff voltage may be limited to the upper limit voltage of the reference voltage range.

[0014] The first protection operation may include an operation of reducing a reference current of the constant current charging by a first compensation current corresponding to a voltage difference between the first characteristic voltage and the reference voltage.

[0015] The control unit may be configured to perform a second protection operation on the battery when an additional characteristic point having a second characteristic voltage greater than the first characteristic voltage is detected from the differential capacity curve.

[0016] The second protection operation may include an operation of additionally reducing the reference current reduced by the first protection operation.

[0017] The control unit may be configured to stop the constant current charging when no characteristic point is detected from the differential capacity curve.

[0018] The control unit may be configured to determine the reference voltage range based on a maximum capacity of the battery.

[0019] A battery pack according to another aspect of the present disclosure includes a battery management system.

[0020] An electric vehicle according to still another aspect of the present disclosure includes a battery pack.

[0021] A battery management method according to another aspect of the present disclosure can be performed at predetermined time intervals during constant current charging of a battery. The battery management method includes the following steps: recording a voltage history and a current history of the battery based on a voltage signal indicating the voltage of the battery and a current signal indicating the current flowing through the battery; determining a differential capacity curve indicating a correlation between the voltage and differential capacity of the battery within a reference voltage range based on the voltage history and the current history; and, when a main characteristic point is detected from the differential capacity curve, performing a first protection operation on the battery by comparing a first characteristic voltage of the main characteristic point with a reference voltage.

[0022] The battery management method may further include performing a second protection operation on the battery when an additional characteristic point having a second characteristic voltage greater than the first characteristic voltage is detected from the differential capacity curve.

[0023] Technical Effects

[0024] According to at least one embodiment of the present disclosure, after determining a differential capacity curve within a preset voltage range where a single phase change reaction occurs during battery charging, the polarization level may be determined by referring to a characteristic point detection result of the differential capacity curve.

[0025] In addition, according to at least one embodiment of the present disclosure, different protection operations are performed on the battery using the polarization level determined based on the characteristic point detection results with reference to the differential capacity curve, thereby delaying battery degradation and improving safety.

[0026] The effects of the present disclosure are not limited to the above-described effects, and those skilled in the art will clearly understand these and other effects from the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the present disclosure described below, serve to provide a further understanding of the technical aspects of the present disclosure, and thus the present disclosure should not be construed as being limited to the accompanying drawings.

[0028] Figure 1 is a diagram schematically illustrating an exemplary configuration of an electric vehicle according to the present disclosure.

[0029] Figure 2 is a graph illustrating exemplary differential capacitance curves for voltage range intervals including a reference voltage range.

[0030] Figure 3 is a graph showing an example correlation between the maximum capacity of a battery and a reference voltage range.

[0031] Figure 4 is a flowchart exemplarily illustrating a battery management method according to the first embodiment of the present disclosure.

[0032] Figure 5 is a flowchart exemplarily illustrating a battery management method according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] 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 interpreted as being limited to the general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical solutions of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms in order to obtain the best interpretation.

[0034] Therefore, the embodiments described herein and the illustrations shown in the accompanying drawings are merely the most preferred embodiments of the present disclosure and are not intended to fully describe the technical aspects of the present disclosure. Therefore, it should be understood that various other equivalent replacements and modifications can have been made thereto when this application is filed.

[0035] Terms including ordinal numbers such as “first,” “second,” etc. are used to distinguish one element from other elements among various elements, but are not intended to limit the elements by these terms.

[0036] Unless otherwise clearly indicated in the context, it should be understood that the term "comprising" when used in this specification specifies the presence of the mentioned elements, but does not exclude the presence or addition of one or more other elements. Additionally, the term "control unit" refers to a processing unit of at least one function or operation, and it can be implemented by hardware and software alone or in combination.

[0037] Furthermore, 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.

[0038] Figure 1 is a diagram schematically illustrating an exemplary configuration of an electric vehicle according to the present disclosure.

[0039] Reference Figure 1 The battery pack 10 is configured to be mountable on an electric device such as an electric vehicle 1. The battery pack 10 includes a battery B, a switch SW, a charging circuit 20, and a battery management system 100.

[0040] The positive terminal and negative terminal of battery B are electrically connected to the battery management system 100. Battery B is a lithium-ion battery and includes a positive electrode, a negative electrode, and a separator. The separator is placed between the positive electrode and the negative electrode to isolate the positive electrode from the negative electrode. The positive electrode active material may include a lithium metal composite oxide, such as LiNi 8 / 10 Co 1 / 10 Mn1 / 10 O 2. The negative electrode active material may include, for example, a carbon-based material (eg, graphite).

[0041] When the polarization phenomenon of battery B is less than a predetermined level, a single phase change reaction of the positive electrode active material or the negative electrode active material occurs in the reference voltage range (for example, 3.6V to 3.8V). The capacity of battery B varies greatly based on the voltage at which the phase change reaction occurs. Therefore, after obtaining the differential capacitance curve of the reference voltage range interval, the polarization level can be determined based on the characteristic point detection result of the reference differential capacitance curve. The polarization phenomenon can be simply referred to as "polarization", and the degree of the polarization phenomenon can be referred to as "polarization level". Each characteristic point of the differential capacitance curve can be used as information indicating the voltage at which the phase change reaction occurs.

[0042] A switch SW is installed in a current path connected in series to battery B and is used to charge and discharge battery B. When switch SW is turned on, battery B can be charged and discharged. Switch SW can be a mechanical relay that is turned on and off by the electromagnetic force of a coil, or a semiconductor switch such as a metal oxide semiconductor field effect transistor (MOSFET). When switch SW is turned off, charging and discharging of battery B stops. Switch SW can be turned on in response to a first switching signal (e.g., a high-level voltage). Switch SW can be turned off in response to a second switching signal (e.g., a low-level voltage).

[0043] The charging circuit 20 is electrically connected to the current path for charging and discharging the battery B. The charging circuit 20 is configured to convert AC power from an external device (e.g., a commercial power source) into DC power. The charging circuit 20 may include a constant current circuit to adjust the current rate (referred to as "C-rate") used for constant current charging according to commands from the battery management system 100.

[0044] The battery management system 100 is configured to protect the battery B from excessive polarization. The battery management system 100 includes a sensing unit 110 , a control unit 120 , and a storage unit 130 . The battery management system 100 may further include an interface unit 140 . The battery management system 100 may further include a switch driver 150 .

[0045] Sensing unit 110 includes a voltage sensor 111 and a current sensor 112. Voltage sensor 111 is connected in parallel to battery B and is configured to detect the voltage across battery B and generate a voltage signal indicating the detected voltage. Current sensor 112 is connected in series with battery B via a current path. Current sensor 112 is configured to detect the current flowing through battery B and generate a current signal indicating the detected current. Control unit 120 can synchronously collect sensing information including the voltage signal and the current signal from sensing unit 110.

[0046] 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, or an electronic unit for performing other functions.

[0047] The control unit 120 is operatively coupled to the charging circuit 20 and the sensing unit 110. The term "operatively coupled" refers to a direct / indirect connection to enable transmission and reception of signals in one or both directions. The control unit 120 is configured to perform operations for protecting the battery B as described below.

[0048] When the voltage of battery B is less than the lower limit voltage of the reference voltage range, control unit 120 may send a charge start command to charging circuit 20. The charge start command includes information indicating the current rate of the reference current. In response to the charge start command, charging circuit 20 performs constant current charging of battery B using the reference current.

[0049] The control unit 120 is configured to determine the voltage, current, capacity, and state of charge (SOC) of the battery B at predetermined time intervals based on the voltage signal and current signal included in the sensing information during constant-current charging of the battery B. The SOC can be determined using at least one of various well-known algorithms (e.g., an ampere-hour integration method and a Kalman filter method), and a detailed description thereof is omitted.

[0050] The capacity of Battery B represents the amount of charge stored in Battery B, which can be referred to as "remaining capacity." It can be determined by integrating the current flowing through Battery B over predetermined time intervals. The SOC of Battery B represents the ratio of the capacity of Battery B to the maximum capacity of Battery B (abbreviated as "full charge capacity") and is typically expressed as a scale of 0 to 1 or 0 to 100%. As Battery B degrades, its maximum capacity gradually decreases.

[0051] Control unit 120 may record, in storage unit 130, a voltage history, a current history, and a capacity history corresponding to the voltage, current, and capacity, respectively, obtained at predetermined time intervals during constant current charging. Capacity history is based on current history. The history of a parameter refers to the time series changes in the corresponding parameter over a period of time.

[0052] The storage unit 130 is operably coupled to the control unit 120. The storage unit 130 may also be operably coupled to the sensing unit 110. The storage unit 130 may include, for example, at least one type of storage medium selected from the group consisting of a flash memory type, a hard disk type, a solid state drive (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).

[0053] The storage unit 130 may store data and programs required for the control unit 120 to perform calculation operations. The storage unit 130 may store data indicating results of calculation operations performed by the control unit 120.

[0054] The interface unit 140 is configured to support wired or wireless communication between the control unit 120 and the higher-level controller 2 (e.g., ECU: Electronic Control Unit) of the electric vehicle 1. Wired communication can be, for example, controller area network (CAN) communication, while wireless communication can be, for example, Zigbee or Bluetooth communication. The communication protocol is not limited to a specific type and can include any communication protocol that supports wired / wireless communication between the control unit 120 and the higher-level controller 2. The interface unit 140 may include an output device (e.g., a display, a speaker) to provide information received from the control unit 120 and / or the higher-level controller 2 in a recognizable format.

[0055] The switch driver 150 is electrically coupled to the control unit 120 and the switch SW. The switch driver 150 is configured to selectively output a first switching signal or a second switching signal to the switch SW in response to a command from the control unit 120. The control unit 120 may command the switch driver 150 to turn on the switch SW during constant current charging of the battery B.

[0056] Figure 2 is a graph showing exemplary differential capacitance curves for voltage ranges including a reference voltage range, and Figure 3 is a graph showing an example correlation between the maximum capacity of a battery and a reference voltage range.

[0057] Through experiments in which the polarization level was forcibly increased during constant current charging, the inventors discovered the following: First, as the polarization level increased, the voltage at which the phase change reaction occurred gradually increased (i.e., shifted to a higher voltage). Second, as the polarization level increased further, the phase change reaction gradually occurred over a wider voltage range, or the phase change reaction was segmented into separate voltage ranges.

[0058] In the specification, the differential capacity curve may refer to a data set recording the correlation between the voltage and differential capacity of battery B. The differential capacity refers to the ratio dQ / dV of the capacity change dQ of battery B to the voltage change dV of battery B at a predetermined time interval.

[0059] exist Figure 2 In, V L and V U Respectively represent the lower limit voltage and upper limit voltage of the reference voltage range ΔV, V E Indicates the cut-off voltage of constant current charging. Figure 2 , the first curve 201 represents the differential capacity curve of battery B without polarization, the second curve 202 represents the differential capacity curve when the polarization level of battery B is less than a predetermined level, and the third curve 203 represents the differential capacity curve when the polarization level of battery B is equal to or greater than a predetermined level. In each of the curves 201, 202, and 203, the characteristic point that first appears in the reference voltage range ΔV can be called a "main characteristic point". For example, a characteristic point generally refers to at least one of a maximum point, a minimum point, and an inflection point, or a point that meets a specific condition. Figure 2 , the maximum point that first appears in the reference voltage range ΔV in each of the curves 201 , 202 , 203 is shown as a main characteristic point.

[0060] The control unit 120 controls the battery B to charge even when the voltage of the battery B reaches the upper limit voltage V U Before that, the characteristic points appearing in the differential capacity curve may also be detected at predetermined time intervals. Alternatively, the control unit 120 may detect the characteristic points appearing in the differential capacity curve at predetermined time intervals. U Then, all characteristic points appearing in the differential capacity curve within the reference voltage range ΔV are detected simultaneously.

[0061] Describing the first curve 201, there is a single characteristic point P1 in the reference voltage range ΔV. The storage unit 130 may pre-store a data set corresponding to the first curve 201. The control unit 120 may set the reference voltage for determining the polarization level occurring in the battery B to be equal to the characteristic voltage V1 of the characteristic point P1.

[0062] Describing the second curve 202, a single characteristic point P2 exists within the reference voltage range ΔV. It can be seen that characteristic point P2 shifts toward a higher voltage from characteristic point P1. That is, characteristic voltage V2 at characteristic point P2 is higher than characteristic voltage V1 at characteristic point P1, and during the acquisition of second curve 202, the voltage difference between characteristic voltage V2 and characteristic voltage V1 has a positive correlation with the polarization level occurring during constant current charging.

[0063] The control unit 120 may perform the first protection operation based on the voltage difference between the characteristic voltage V2 and the characteristic voltage V1. The control unit 120 may start performing the first protection operation from the time point when the characteristic point P2 is detected.

[0064] The first protection operation may include an operation of reducing the cutoff voltage of the constant current charging by a compensation voltage corresponding to the voltage difference. The control unit 120 may determine the compensation voltage to be equal to the product of the voltage difference multiplied by a predetermined first weight. Wherein the voltage difference = V2-V1 = 0.1 [V], and the first weight = 0.9, V E =4.0[V], compensation voltage = 0.09[V], reduced cutoff voltage = V E -0.09[V]=3.91[V]=V E '. The control unit 120 can reduce the cut-off voltage V E ’ is set as the cut-off voltage for constant current charging.

[0065] The first protection operation may include an operation of reducing the reference current by a compensation current corresponding to the voltage difference. The control unit 120 may determine the compensation current to be equal to the product of the voltage difference multiplied by a predetermined second weight. Assuming that the voltage difference = V2-V1 = 0.1 [V], the second weight = 0.5 [C-rate / V], and the reference current = 0.50 [C-rate], then the compensation current = 0.05 [C-rate], and the reduced reference current = 0.50-0.05 [C-rate] = 0.45 [C-rate]. The control unit 120 may set the reduced reference current as the reference current for constant current charging.

[0066] Describing the third curve 203, there are two characteristic points P3 and P A It can be seen that characteristic point P3 shifts to a higher voltage from characteristic point P1 than characteristic point P2. That is, characteristic voltage V3 of characteristic point P3 is higher than characteristic voltage V2 of characteristic point P2, and the voltage difference between characteristic voltage V3 and characteristic voltage V1 represents the polarization level that occurs during constant current charging during the acquisition of third curve 203.

[0067] The control unit 120 may perform a first protection operation based on the voltage difference between the characteristic voltage V3 and the characteristic voltage V1. The description of the first protection operation is the same as that of the second curve 202. That is, the control unit 120 may reduce the cutoff voltage and / or the reference current as the first protection operation.

[0068] Assume that the third curve 203 is obtained after the second curve 202 is obtained. When the cut-off voltage is reduced, the voltage difference = V3 - V1 = 0.12 [V], the first weight = 0.9, V E′=3.91[V], compensation voltage=0.108[V], reduced cutoff voltage=V E ′-0.108[V]=3.802[V]=V E ”. The control unit 120 can reduce the cut-off voltage V E ″ is set to the cut-off voltage of constant current charging. The lower limit of the cut-off voltage can be limited to the upper limit voltage V U When reducing the reference current, the voltage difference = V3 - V1 = 0.12 [V], the second weight = 0.5 [C-rate / V], the reference current = 0.45 [C-rate], the compensation current = 0.06 [C-rate], and the reduced reference current = 0.45 - 0.06 [C-rate] = 0.39 [C-rate]. The control unit 120 can set the reduced reference current as the reference current for constant current charging.

[0069] The control unit 120 may monitor the characteristic voltage V3 and the upper limit voltage V at predetermined time intervals after detecting the characteristic point P3. U The control unit 120 may detect a point where the slope of the third curve 203 is equal to or greater than a predetermined threshold or a minimum point of the third curve 203 as an additional feature point.

[0070] exist Figure 2 The first time it appears between the characteristic voltage V3 and the upper limit voltage V U The minimum point P between A are shown as being detected as additional feature points. A With characteristic voltage V3 and upper limit voltage V U The characteristic voltage V A .

[0071] When additional feature points P are detected A The control unit 120 may perform a second protection operation when the additional feature point P is detected. A The second protection operation starts at the time point of

[0072] The second protection operation may include an operation of additionally reducing the reference current. Assume that an additional feature point P is detected after the reference current is reduced from 0.45 [C-rate] to 0.39 [C-rate] by the first protection operation. A In this case, the control unit 120 may set 0.351 [C-rate] obtained by multiplying the reference current 0.39 [C-rate] by the third weight (eg, 0.9) as the reference current for constant current charging.

[0073] Lower limit voltage V L and upper limit voltage VU Alternatively, the control unit 120 may calculate the maximum capacity Q of the battery B at the start of constant current charging based on the maximum capacity Q of the battery B. MAX To determine the lower limit voltage V of the reference voltage range ΔV L and upper limit voltage V U The maximum capacity Q can be determined according to at least one of various well-known algorithms. MAX , and its detailed description is omitted.

[0074] The relationship between the degree of degradation of battery B and the phase change reaction is similar to the relationship between polarization and the phase change reaction. Therefore, in order to more accurately detect the polarization occurring in battery B from the differential voltage curve, it may be advantageous to determine the reference voltage range ΔV based on the maximum capacity of battery B corresponding to the degree of degradation. Figure 3 , curve 301 represents the relationship between the maximum capacity and the lower limit voltage, and curve 302 represents the relationship between the maximum capacity and the upper limit voltage. The above curve 301 can be prepared based on the experimental results of a battery manufactured to have the same electrical and chemical properties as battery B. Figure 3 The storage unit 130 may pre-store data sets (eg, a lookup table) corresponding to the two curves 301 and 302. For example, when the maximum capacity of battery B is Q MAX When the control unit 120 can MAX Associated V X and V Y Set as voltage V L and upper limit voltage V U .

[0075] Figure 4 is a flowchart exemplarily showing a battery management method according to the first embodiment of the present disclosure, and Figure 5 203 is a flowchart exemplarily showing a battery management method according to the second embodiment of the present disclosure. Figure 4 and Figure 5 During the constant current charging of battery B, the Figure 4 until the main characteristic point P3 of the differential capacity curve 203 is detected or the voltage of the battery B reaches the upper limit voltage V U Until now. Figure 4 Under the condition that the main feature point P3 is detected by the method, the Figure 5 until an additional characteristic point P of the differential capacity curve 203 is detected. A , or the voltage of battery B reaches the upper limit voltage V U until.

[0076] Reference Figures 1 to 4 In step S400, the control unit 120 records the voltage history and current history of the battery B based on the voltage signal from the voltage sensor 111 and the current signal from the current sensor 112. That is, the voltage history and current history are updated at predetermined time intervals.

[0077] In step S410, the control unit 120 determines whether the voltage of the battery B reaches the lower limit voltage V of the reference voltage range ΔV. L When the value of step S410 is "yes", execute step S420. When the value of step S410 is "no", Figure 4 The method can end.

[0078] In step S420 , the control unit 120 determines a differential capacity curve 203 indicating the correlation between the voltage and differential capacity of battery B based on the voltage history and the current history. That is, each time step S420 is performed, the differential capacity curve 203 may be updated with voltage information and capacity information newly added for a predetermined time.

[0079] In step S430, the control unit 120 determines whether the main feature point P3 of the differential capacity curve 203 is detected. When the value of step S430 is "yes", step S440 is performed. When the value of step S430 is "no", step S450 may be performed.

[0080] At step S440, the control unit 120 performs a first protection operation. The first protection operation reduces the cutoff voltage or the reference current. The control unit 120 may send a first charge current reduction command to the charging circuit 20, indicating the reduced reference current. The charging circuit 20 may reduce the magnitude of the reference current in response to the first charge current reduction command.

[0081] In step S450, the control unit 120 determines whether the voltage of the battery B reaches the upper limit voltage V of the reference voltage range ΔV. U When the value of step S450 is "yes", step S460 can be executed. When the value of step S450 is "no", it means that the polarization is too severe to be suppressed or a fault has occurred in the battery management system 100. When the value of step S450 is "no", Figure 4 The method can end.

[0082] In step S460, the control unit 120 stops constant current charging. That is, the control unit 120 sends a charge stop command to the charging circuit 20. The charging circuit 20 may stop providing the reference current in response to the charge stop command. Alternatively or additionally, the control unit 120 may turn off the switch SW.

[0083] Reference Figure 5In step S500 , the control unit 120 records the voltage history and the current history of the battery B based on the voltage signal from the voltage sensor 111 and the current signal from the current sensor 112 .

[0084] In step S510 , the control unit 120 determines the differential capacity curve 203 indicating the correlation between the voltage and the differential capacity of the battery B based on the voltage history and the current history.

[0085] In step S520, the control unit 120 determines whether an additional feature point P of the differential capacity curve 203 is detected. A When the value of step S520 is "yes", step S530 is executed. When the value of step S520 is "no", step S540 may be executed.

[0086] In step S530, the control unit 120 performs a second protection action. The second protection action may additionally reduce the reference current. The control unit 120 may send a second charging current reduction command to the charging circuit 20, instructing the charging circuit 20 to additionally reduce the reference current. In response to the second charging current reduction command, the charging circuit 20 may additionally reduce the magnitude of the reference current.

[0087] The embodiments of the present disclosure described above are not only implemented by devices and methods, but can also be implemented by programs that execute functions corresponding to the configurations of the embodiments of the present disclosure or recording media on which the programs are recorded, and those skilled in the art can easily achieve such implementation based on the disclosure content of the embodiments described above.

[0088] Although the present disclosure has been described above with reference 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 may be made thereto within the technical solutions within the scope of the present disclosure and the equivalents of the appended claims.

[0089] Additionally, since those skilled in the art can make many substitutions, modifications and variations to the present disclosure described above without departing from the technical solutions of the present disclosure, the present disclosure is not limited to the above-mentioned embodiments and drawings, and some or all of the embodiments can be selectively combined to allow various modifications.

[0090] This application claims the benefit of Korean Patent Application No. 10-2020-0089755 filed on July 20, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A battery management system, comprising: a voltage sensor configured to generate a voltage signal indicative of a voltage of the battery; a current sensor configured to generate a current signal indicative of current flowing through the battery; as well as a control unit configured to record a voltage history and a current history of the battery based on the voltage signal and the current signal at predetermined time intervals during constant current charging of the battery, Wherein, the control unit is configured as follows: determining a differential capacity curve indicating a correlation between a voltage and a differential capacity of the battery within a reference voltage range based on the voltage history and the current history, and When a main characteristic point is detected from the differential capacity curve, a first protection operation is performed on the battery by comparing a first characteristic voltage of the main characteristic point with a reference voltage. In the differential capacity curve, the characteristic point that first appears within the reference voltage range is called the main characteristic point.

2. The battery management system according to claim 1, wherein: The control unit is configured to determine a maximum point detected for the first time from the differential capacity curve during the constant current charging of the battery as the main characteristic point.

3. The battery management system according to claim 1, wherein: The first protection operation includes an operation of reducing the cut-off voltage of the constant current charging by a compensation voltage corresponding to a voltage difference between the first characteristic voltage and the reference voltage, and The lower limit of the cut-off voltage is limited to the upper limit voltage of the reference voltage range.

4. The battery management system according to claim 1, wherein: The first protection operation includes an operation of reducing a reference current of the constant current charging by a first compensation current corresponding to a voltage difference between the first characteristic voltage and the reference voltage.

5. The battery management system according to claim 1, wherein: The control unit is configured to perform a second protection operation on the battery when an additional characteristic point having a second characteristic voltage greater than the first characteristic voltage is detected from the differential capacity curve.

6. The battery management system according to claim 5, wherein: The second protection operation includes an operation of additionally reducing the reference current reduced by the first protection operation.

7. The battery management system according to claim 1, wherein: The control unit is configured to stop the constant current charging when the main characteristic point is not detected from the differential capacity curve.

8. The battery management system according to claim 1, wherein: The control unit is configured to determine the reference voltage range based on a maximum capacity of the battery.

9. The battery management system according to claim 1, wherein: The differential capacity refers to a ratio of a capacity change of the battery to a voltage change of the battery during the predetermined time interval. 10 . A battery pack comprising the battery management system according to claim 1 . 11 . An electric vehicle comprising the battery pack according to claim 10 .

12. A battery management method, the battery management method being performed at predetermined time intervals during constant current charging of a battery, the battery management method comprising the following steps: recording a voltage history and a current history of the battery based on a voltage signal indicating a voltage of the battery and a current signal indicating a current flowing through the battery; determining a differential capacity curve indicating a correlation between a voltage and a differential capacity of the battery within a reference voltage range based on the voltage history and the current history; as well as When a main characteristic point is detected from the differential capacity curve, a first protection operation is performed on the battery by comparing a first characteristic voltage of the main characteristic point with a reference voltage. In the differential capacity curve, the characteristic point that first appears within the reference voltage range is called the main characteristic point.

13. The battery management method according to claim 12, further comprising the following steps: When an additional characteristic point having a second characteristic voltage greater than the first characteristic voltage is detected from the differential capacity curve, a second protection operation is performed on the battery.

14. The battery management method according to claim 12, wherein: The first protection operation includes an operation of reducing the cut-off voltage of the constant current charging by a compensation voltage corresponding to a voltage difference between the first characteristic voltage and the reference voltage, and The lower limit of the cut-off voltage is limited to the upper limit voltage of the reference voltage range.

15. The battery management method according to claim 12, wherein: The first protection operation includes an operation of reducing a reference current of the constant current charging by a first compensation current corresponding to a voltage difference between the first characteristic voltage and the reference voltage.

16. The battery management method according to claim 13, wherein: The second protection operation includes an operation of additionally reducing the reference current reduced by the first protection operation.

Images