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

Abstract

A battery management system according to the present invention includes: a sensing unit that generates sensing signals indicating battery voltage and battery current; a storage unit that stores a charging map recording the relationships between a first reference SOC range to an nth reference SOC range, a first reference current to an nth reference current, and a first reference voltage to an nth reference voltage for multi-level constant current charging; and a control unit that, during constant current charging using a kth reference current corresponding to a kth reference SOC range, switches to constant voltage charging using a kth reference voltage in response to the battery voltage reaching a kth reference voltage corresponding to the kth reference SOC range in which the battery's SOC is located. During constant voltage charging, in response to the battery's SOC reaching the upper limit of the kth reference SOC range, the control unit updates the kth reference current of the charging map based on the time series of the battery current during the constant voltage charging period.

Description

Technical Field

[0001] This disclosure relates to battery charging control.

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0101934, filed with the Korean Intellectual Property Office on August 13, 2020, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0003] Recently, the demand for portable electronic products (such as laptops, cameras, and mobile phones) has increased rapidly, and with the widespread development of electric vehicles, batteries for energy storage, robots, and satellites, there is a great deal of research being conducted on high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently, batteries available on the market include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have almost no memory effect or no memory effect at all, so they are more popular than nickel-based batteries because their advantages are that they can be recharged easily, have a very low self-discharge rate, and have high energy density.

[0005] In constant current charging of a battery, when the charging current rate is low, it takes a very long time to fully charge the battery. Conversely, when the charging current rate is too high, the battery deteriorates rapidly.

[0006] One charging scheme proposed to address this problem is 'multi-stage constant current charging', which involves progressively adjusting the charging current rate based on the battery's state of charge (SOC) or voltage during charging. The current rate is obtained by dividing the charging current by the battery's maximum capacity and can be referred to as the "C-rate," with the unit being "C." A multi-stage constant current charging graph comprises at least one data array recording the interrelationships between multiple C-rates and multiple SOC ranges. The charging process using a multi-stage constant current charging graph involves repeatedly supplying the battery with the next C-rate charging current whenever the battery's SOC reaches the upper limit of each SOC range.

[0007] As a battery deteriorates from the beginning of its life (BOL), the degradation at the same C-rate can be accelerated. However, the charging process using a conventional multi-stage constant current charging diagram does not take into account battery degradation. Summary of the Invention

[0008] Technical issues

[0009] This disclosure is designed to solve the above-mentioned problems, and therefore aims to provide a battery management system, battery management method, battery pack, and electric vehicle, wherein the multi-level constant current charging map is updated based on the battery voltage and battery current monitored during charging using a multi-level constant current charging map.

[0010] This disclosure also aims to provide a battery management system, battery management method, battery pack, and electric vehicle, wherein even after the charging process has ended after only some of the multiple states of charge (SOC) ranges have been charged, the C-rate of each of the remaining SOC ranges is updated based on the C-rate update results of the SOC ranges that have already undergone the charging process.

[0011] These and other objects and advantages of this disclosure will be understood from the following description and will be apparent from embodiments of this disclosure. Furthermore, it will be readily understood that the objects and advantages of this disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0012] Technical solution

[0013] A battery management system according to one aspect of this disclosure includes: a sensing unit configured to generate sensing signals indicating battery voltage and battery current; a storage unit configured to store a charging map recording the relationships between a first reference state of charge (SOC) range to an nth reference state of charge (SOC), a first reference current to an nth reference current, and a first reference voltage to an nth reference voltage for multi-level constant current charging; and a control unit configured to, in response to a charging start command, begin constant current charging using a kth reference current corresponding to a kth reference SOC range to which the SOC of the battery belongs within the first to nth reference SOC ranges. The control unit is configured to, in response to a situation where the battery voltage has reached a kth reference voltage corresponding to the kth reference SOC range before the SOC of the battery reaches the upper limit of the kth reference SOC range during constant current charging, switch from constant current charging to constant voltage charging using the kth reference voltage. The control unit is configured to update the k-th reference current of the charging map based on the time series of the battery current during the charging period of constant voltage charging, in response to the battery's SOC reaching the upper limit of the k-th reference SOC range during constant voltage charging. n is a natural number of 2 or greater, and k is a natural number of n or less.

[0014] The control unit can be configured to determine the average current during a charging period from a time series of battery currents. The control unit can also be configured to update the k-th reference current to be equal to the average current.

[0015] The control unit can be configured to determine the average current during a charging period based on a time series of the battery current. The control unit can also be configured to update the k-th reference current to the sum of the product of the k-th reference current and a first weight, and the product of the average current and a second weight.

[0016] Each of the first weight and the second weight can be a positive number less than 1, and the sum of the first weight and the second weight can be 1.

[0017] The control unit can be configured to update each of the remaining reference currents from the first to the nth reference currents, except for the kth reference current, based on the updated ratio of the kth reference current to the kth reference current.

[0018] According to another aspect of this disclosure, the battery pack includes a battery management system.

[0019] According to another aspect of this disclosure, an electric vehicle includes a battery pack.

[0020] A battery management method according to another aspect of this disclosure includes: in response to a charging start command, initiating constant current charging using a k-th reference current corresponding to a k-th reference state of charge (SOC) range to which the SOC of a battery within a first to n-th reference SOC range belongs, the first to n-th reference SOC ranges being derived from a charging graph recording the interrelationships between the first to n-th reference SOC ranges, the first to n-th reference currents, and the first to n-th reference voltages for multi-level constant current charging; switching from constant current charging to constant voltage charging using the k-th reference voltage in response to a battery voltage corresponding to the k-th reference SOC range reaching the upper limit of the k-th reference SOC range before the SOC of the battery reaches the upper limit of the k-th reference SOC range during constant current charging; and updating the charging graph based on a time series of the battery current during the charging period of the constant voltage charging in response to the SOC of the battery reaching the upper limit of the k-th reference SOC range during the constant voltage charging period. n is a natural number of 2 or greater, and k is a natural number of n or less.

[0021] Updating the k-th reference current of the charging map may include determining the average current during the charging period from the time series of the battery current, and updating the k-th reference current to be equal to the average current.

[0022] The battery management method may also include updating the first reference current to each remaining reference current in the nth reference current other than the kth reference current based on the ratio between the kth reference current and the updated kth reference current.

[0023] Beneficial effects

[0024] According to at least one embodiment of this disclosure, the multi-level constant current charging map can be updated based on the battery voltage and battery current monitored during charging using the multi-level constant current charging map.

[0025] Furthermore, according to at least one embodiment of this disclosure, even after the charging process ends after only performing the charging process on some of the multiple states of charge (SOC) ranges, the C-rate of each of the remaining SOC ranges can be updated based on the C-rate update result of the SOC ranges that have already undergone the charging process.

[0026] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand these and other effects based on the appended claims. Attached Figure Description

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

[0028] Figure 1 The diagram illustrates, exemplarily, the construction of an electric vehicle according to this disclosure.

[0029] Figure 2 This is an example diagram illustrating the relationship between the reference current and the range of the reference state of charge (SOC) recorded in the charging diagram.

[0030] Figure 3 It is an exemplary diagram showing the relationship between the reference voltage and the reference SOC range recorded in the charging diagram.

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

[0032] Figure 5 This is a flowchart illustrating, exemplarily, a battery management method according to a second embodiment of the present disclosure. Detailed Implementation

[0033] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their general or dictionary meanings, but rather are interpreted based on the principle that inventors are allowed to appropriately define terms for the best interpretation, and on the meanings and concepts corresponding to the technical aspects of the present disclosure.

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

[0035] Ordinal terms such as “first” and “second” are used to distinguish one element from another among various elements, but are not intended to limit these elements by these terms.

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

[0037] Furthermore, as will be further understood throughout the specification, when an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element.

[0038] Figure 1 The diagram illustrates, exemplarily, the construction of an electric vehicle according to this disclosure.

[0039] See Figure 1 The electric vehicle 1 includes a battery pack 10, an inverter 30, an electric motor 40, and a charging circuit 50.

[0040] The battery pack 10 includes a battery B, a switch 20, and a battery management system 100.

[0041] Battery B includes at least one battery cell. Each battery cell is not limited to a specific type and may include any battery cell capable of being repeatedly recharged, such as a lithium-ion cell. Battery B can be connected to converter 30 and / or charging circuit 50 via a pair of power terminals disposed in battery pack 10.

[0042] Switch 20 is connected in series with battery B. Switch 20 is installed in the current path for charging / discharging battery B. Switch 20 is controlled to be turned on / off in response to a switching signal from battery management system 100. Switch 20 can be a mechanical relay that is turned on / off by the electromagnetic force of a coil or a semiconductor switch such as a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0043] A converter 30 is provided to convert direct current (DC) from battery B into alternating current (AC) in response to a command from the battery management system 100. The electric motor 40 may be, for example, a three-phase AC electric motor. The electric motor 40 operates using AC power from the converter 30.

[0044] The battery management system 100 is responsible for general control related to the charging / discharging of battery B. The battery management system 100 includes a sensing unit 110, a storage unit 120, and a control unit 140. The battery management system 100 may further include at least one of an interface unit 130 or a switch driver 150.

[0045] The sensing unit 110 includes a voltage sensor 111 and a current sensor 112. The sensing unit 110 may also include a temperature sensor 113.

[0046] Voltage sensor 111 is connected in parallel with battery B and configured to detect the battery voltage across battery B and generate a voltage signal indicating the detected battery voltage. Current sensor 112 is connected in series with battery B via a current path. Current sensor 112 is configured to detect the battery current flowing through battery B and generate a current signal indicating the detected battery current. Temperature sensor 113 is configured to detect the temperature of battery B and generate a temperature signal indicating the detected temperature.

[0047] Storage unit 120 may include at least one type of storage medium selected from flash memory, hard disk, solid-state drive (SSD), silicon disk drive (SDD), multimedia card micro, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or programmable read-only memory (PROM). Storage unit 120 may store data and programs required for the calculation operations of control unit 140. Storage unit 120 may also store data indicating the results of the calculation operations of control unit 140.

[0048] Storage unit 120 stores a charging map. The charging map may be pre-stored in storage unit 120 before loading battery management system 100, or may be received from, for example, a battery manufacturer or advanced controller 2 via interface unit 130.

[0049] A charging diagram is used during the multi-stage constant current charging process of battery B. The charging diagram stores the relationships between the first to nth reference SOC ranges, the first to nth reference currents, and the first to nth reference voltages used for multi-stage constant current charging. n is a natural number of 2 or greater. Earlier reference currents can be less than later reference currents.

[0050] Interface unit 130 may include communication circuitry configured to support wired or wireless communication between control unit 140 and advanced controller 2 (e.g., electronic control unit (ECU)). Wired communication may be, for example, Controller Area Network (CAN) communication, while wireless communication may be, for example, Zigbee or Bluetooth communication. The communication protocol is not limited to a specific type and may include any communication protocol supporting wired / wireless communication between control unit 140 and advanced controller 2. Interface unit 130 may include output devices (e.g., a display, a speaker) to provide information received from control unit 140 and / or advanced controller 2 in a recognizable format. Advanced controller 2 may control converter 30 based on battery information (e.g., voltage, current, temperature, SOC) collected through communication with battery management system 100.

[0051] The control unit 140 can be operatively coupled to the advanced controller 2, switch 20, charging circuit 50, sensing unit 110, storage unit 120, interface unit 130, and / or switch driver 150. Ooperatively coupled means directly or indirectly connected to transmit and receive signals in one or both directions.

[0052] Switch driver 150 is electrically connected to control unit 140 and switch SW. Switch driver 150 is configured to selectively turn switch SW on / off in response to a command from control unit 140. Control unit 140 may command switch driver 150 to turn on switch SW during the charging process.

[0053] The control unit 140 can collect sensing signals from the sensing unit 110. The sensing signals synchronously indicate the detected voltage signal, the detected current signal, and / or the detected temperature signal.

[0054] The control unit 140 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 electrical unit for performing other functions.

[0055] Interface unit 130 can relay bidirectional communication between control unit 140 and charging circuit 50, as well as bidirectional communication between control unit 140 and advanced controller 2. Charging circuit 50 is configured to provide battery B with a C-rate charging current requested from battery management system 100. Charging circuit 50 can be configured to supply battery B with a charging voltage having a voltage level requested from battery management system 100. Control unit 140 is configured to initiate a charging process using a charging diagram in response to receiving a charging start command through interface unit 130. Control unit 140 can terminate the charging process using a charging diagram in response to receiving a charging stop command through interface unit 130.

[0056] The control unit 140 can determine the state of charge (SOC) of battery B based on the sensed signal. Known algorithms can be used to determine the SOC, such as open-circuit voltage (OCV)-SOC curves, ampere counting, and Kalman filters.

[0057] Figure 2 It is an exemplary diagram showing the relationship between the reference current and the reference SOC range recorded in the charging diagram, and Figure 3 This is an exemplary diagram showing the relationship between the reference voltage and the reference SOC range recorded in the charging diagram. For ease of description, Figure 2 and 3 The diagram shows n=4, meaning the charging diagram defines the relationships between four reference SOC ranges, four reference currents, and four reference voltages.

[0058] Figure 2 The first current distribution 210 shown indicates the relationship between the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 and the first to fourth reference currents I1 to I4 of battery B at the beginning of its life (BOL). The first current distribution 210 can be recorded in the charging diagram in a datasheet format. When k is a natural number n or smaller, S... k It is the range of the k-th reference SOC, ΔSOC. k The upper limit of S. When m is a natural number less than n, m Equal to the (m+1)th reference SOC range ΔSOC m+1 The lower limit value. For example, S1 is the lower limit value of the second reference SOC range ΔSOC2 with S2 as the upper limit value. The lower limit value S0 of the first reference SOC range ΔSOC1 can be 0 [%.

[0059] When the SOC of battery B is in the m-th reference SOC range ΔSOC m When the time is right, the control unit 140 can command the use of the m-th reference current I. m A constant current is applied to the charging circuit 50.

[0060] Using the m-th reference current I m During constant current charging, when the SOC of battery B reaches the m-th reference SOC range ΔSOC... m The upper limit value S m At that time, the control unit 140 can command the (m+1)th reference current I to be used. m+1 The charging circuit 50 is charged with a constant current.

[0061] Using the nth reference current I n During constant current charging, when the SOC of battery B reaches the nth reference SOC range ΔSOC... n The upper limit value S n At this time, the control unit 140 can command the charging circuit 50 to perform constant voltage charging. Therefore, multi-stage constant current charging using the charging diagram can be terminated and changed to constant voltage charging.

[0062] Figure 3 The first voltage distribution 310 shown illustrates the relationship between battery B in the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 of BOL and the first to fourth reference voltages V1 to V4. The first voltage distribution 310 can be recorded in the charging diagram in a datasheet format. k The reference voltage is preset to represent the voltage at which battery B reaches the k-th reference SOC range ΔSOC at BOL. k The upper limit value S k The battery voltage at that time.

[0063] Furthermore, as mentioned above, as battery B gradually degrades, the voltage rises faster with the same charging current compared to when battery B is at BOL. Therefore, compared to when battery B is at BOL, the voltage rises faster with the k-th reference current I using the charging diagram. k The constant current charging period has reached the k-th reference voltage V. k The battery voltage indicates that battery B is deteriorating. Figure 3 The second voltage distribution shown indicates the change in battery voltage monitored during a constant current charging process of the degraded battery B using the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 in sequence, for each of the first to fourth reference SOC ranges. Reference second voltage distribution 320, V 1k When the SOC of the degraded battery B reaches the k-th reference SOC range ΔSOC k The upper limit value S k The battery voltage at that time was found to be greater than the k-th reference voltage V. k That is, V 11 >V1、V 12 >V2、V 13 >V3、V 14>V4.

[0064] Due to the kth reference voltage V k Is the k-th reference current I used? k The maximum permissible voltage for constant current charging, therefore, within the k-th reference SOC range ΔSOC. k In the middle, the battery voltage is higher than the k-th reference voltage V. k This will accelerate the degradation of battery B. Therefore, when using the k-th reference current I... k During constant current charging, when the battery voltage reaches the k-th reference voltage V k At this time, the charging current needs to be adjusted to be lower than the k-th reference current I. k To suppress the degradation of battery B.

[0065] Figure 2 The second current distribution 220 shown in the figure Figure 3 The third voltage distribution 330 shown in the illustration exemplarily represents a time series, i.e., a history of time-related changes in battery current and battery voltage monitored during charging of a degraded battery B by applying the battery management method according to this disclosure.

[0066] Referring to the third voltage distribution 330, the control unit 140 uses the kth reference current I k During constant current charging, the battery voltage, battery current, and battery SOC are monitored at preset time intervals (e.g., 0.001 seconds). The control unit 140 can monitor the battery voltage, battery current, and battery SOC when the SOC of battery B reaches the k-th reference SOC range ΔSOC. k The upper limit value S k Previously, the response was that the k-th reference voltage V had been reached. k The battery voltage, from using the k-th reference current I k The constant current charging is changed to use the k-th reference voltage V. k The battery is charged at a constant voltage. Therefore, the battery voltage reaches the k-th reference voltage V. k At time k, the SOC of battery B reaches the reference SOC range ΔSOC. k The upper limit value S k At the moment, with the k-th reference voltage V k A constant voltage is applied to charge battery B. Referring to the second current distribution 220, the k-th reference voltage V is used. k During constant voltage charging, the battery current gradually decreases as the battery voltage gradually increases.

[0067] For example, constant current charging using the second reference current I2 is performed within the SOC range of S1 to Z2 [%). Subsequently, while maintaining the battery voltage of battery B equal to the second reference voltage V2, constant voltage charging is performed within the SOC range of Z2 to S2 [%) (the second constant voltage charging range). Furthermore, it can be seen from the second current distribution 220 that when battery B is charged with the second reference voltage V2 at a constant voltage, the battery current gradually decreases from the second reference current I2.

[0068] The control unit 140 can update the battery voltage and battery current based on the battery voltage and battery current monitored during the sequential execution of a charging process for at least one of the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4. Figure 2 The first current distribution 210 and Figure 3 The first voltage distribution is shown in the charging diagram of 310.

[0069] Specifically, the control unit 140 can adjust the charging range Z, which is the kth constant voltage range. k ~S k The k-th average current is determined by the time series (referred to as the "current history") of the battery current monitored during the k-th constant voltage charging period. The k-th average current can be the average of the battery current repeatedly sensed at preset time intervals during the k-th constant voltage charging period. Therefore, the k-th average current is less than the k-th reference current I. k .

[0070] Subsequently, the control unit 140 can update the k-th reference current I of the charging map based on the k-th average current. k . Figure 2 The third current distribution 230 current I 11 ~I 14 These can be the results of updating the reference currents I1 to I4 of the charging diagram.

[0071] Control unit 140 can control the k-th reference current I k Updated to equal the k-th average current. For example, refer to... Figure 2 Where the second reference current I2 = 120A, the second average current = 100A, and the 120A second reference current I2 becomes the 100A I 12 .

[0072] Alternatively, the control unit 140 can transmit the k-th reference current I k Updated to equal the k-th reference current I kThe sum of the product of the first weight and the product of the k-th average current and the second weight. Each of the first and second weights can be a positive number less than 1, and the sum of the first and second weights can be 1. For example, with a second reference current I2 = 120A, a second average current = 100A, a first weight = 0.4, and a second weight = 0.6, the 120A second reference current I2 can be changed to I2 = 108A. 12 And record it in the charging graph.

[0073] Furthermore, although the charging process is not performed sequentially for each of the reference SOC ranges ΔSOC1 to ΔSOC4, the charging process according to the battery management method described above often ends. For example, charging may begin before battery B is fully discharged, or the vehicle user may disconnect the charging cable from electric vehicle 1 before the constant current charging transitions to constant voltage charging. In this case, the reference current corresponding to some reference SOC ranges that have already undergone the charging process described above can be updated, but it is not possible to update the reference current corresponding to the remaining reference SOC ranges.

[0074] To address the aforementioned issues, when charging begins when the SOC of battery B is greater than S0, or ends when the SOC of battery B is less than S4, the control unit 140 can update the reference current associated with each of the remaining reference SOC ranges based on update information of at least one of the reference SOC ranges ΔSOC1 to ΔSOC4.

[0075] Assuming that the battery management method described above only considers the range ΔSOC of the k-th reference SOC... k The corresponding k-th reference current I k Updated to I 1k The control unit 140 can determine I 1k with I k The ratio is determined, and each of the remaining reference currents is updated based on the determined ratio. For example, when the second reference current I2 is updated from 120A to 100A, the control unit 140 can update the first reference current I1, the third reference current I3, and the fourth reference current I4 by multiplying each of the first reference current I1, the third reference current I3, and the fourth reference current I4 by 100 / 120 = 5 / 6.

[0076] Assume that each of i and j is a natural number, i ≤ j, i is 2 or greater, or j is less than n. According to battery management methods (see...), Figure 4 Only the range ΔSOC between the i-th and j-th reference SOCs will be considered. i ~ΔSOC j The corresponding reference currents Ii to Ij from i to j are respectively from I i ~I jUpdated to I 1i ~I 1j And the charging process can then be completed. The control unit 140 can then update each remaining reference current using the following equation.

[0077]

[0078] In the above equation, x is a natural number n or smaller, excluding i to j, and I x This is the reference current before the update, I 1x This is the updated reference current. μ avg The reference current I updated from i to j is 1i ~I 1j With reference currents I from i to j i ~I j The average ratio.

[0079] In one example, with i=2, j=3, and n=4, i1=150A, i2=120A, and i... 12 =100A, i3=110A, i 13 =95A, i4=90A, i 11 =i1×1 / 2×{100 / 120+95 / 110}A≒127A,i 14 = i4×1 / 2×{100 / 120+95 / 110}A≒76A.

[0080] Figure 4 This is a flowchart illustrating, exemplarily, a battery management method according to a first embodiment of the present disclosure.

[0081] Reference Figures 1 to 4 In step S410, the control unit 140 reads charging maps 210 and 310 from the storage unit 120 in response to the charging start command. The charging maps 210 and 310 record the range from the first reference SOC range to the nth reference SOC range ΔSOC1 to ΔSOC. n The first reference current to the nth reference current I1~I n and the first reference voltage to the nth reference voltage V1~V n The interrelationship between them.

[0082] In step S420, the control unit 140 measures the first reference SOC range to the nth reference SOC range ΔSOC1~ΔSOC n Select the k-th reference SOC range ΔSOC to which the SOC of battery B belongs. k For example, when the SOC of battery B is above S1 and less than S2, the second reference SOC range ΔSOC2 is selected.

[0083] In step S430, the control unit 140 begins to use the reference SOC range ΔSOC corresponding to the k-th reference SOC range. k The k-th reference current I k Constant current charging.

[0084] In step S440, the control unit 140 determines that the battery's SOC reaches the k-th reference SOC range ΔSOC. k The upper limit value S k Previously, did the battery voltage reach the range ΔSOC of the k-th reference SOC? k The corresponding k-th reference voltage V k If the value of step S440 is "Yes", then proceed to step S450.

[0085] In step S450, the control unit 140 uses the k-th reference current I k The constant current charging is changed to use the k-th reference voltage V k Charged with a constant voltage.

[0086] In step S460, the control unit 140 determines whether the battery's SOC has reached the k-th reference SOC range ΔSOC. k The upper limit value S k If the value of step S460 is "Yes", then proceed to step S470.

[0087] In step S470, the control unit 140 bases its decision on the k-th reference voltage V. k The current history of the battery current during the constant voltage charging period is used to update the k-th reference current I of the charging map. k .

[0088] In step S480, the control unit 140 determines the k-th reference SOC range ΔSOC. k Is it the nth reference SOC range ΔSOC? n That is, the control unit 140 determines whether the SOC of battery B has reached the maximum SOC S defined by the multi-stage constant current charging as specified in the charging diagram. n If the value of step S480 is "No", the method returns to step S420. If the value of step S480 is "Yes", Figure 4 The method can be completed.

[0089] For reference, when the update conditions are not met but a charging start command is received, it can be obtained from... Figure 4 Steps S440 to S470 are omitted in the method.

[0090] When the pre-defined update conditions are met Figure 4The method may start in response to a charging start command. The update condition is used to prevent unnecessary frequent updates of the charging maps 210, 310. The update condition indicates that the deterioration degree of the battery B increases beyond a predetermined level, and may be, for example, that the cumulative capacity of the battery B increases by at least a first threshold (e.g., 100 Ah [ampere-hour]) compared to the cumulative capacity at the previous update time, the number of cycles of the battery B increases by at least a second threshold (e.g., 50 times) compared to the number of cycles at the previous update time, the capacity retention rate of the battery B decreases by at least a third threshold (e.g., 5%) compared to the capacity retention rate at the previous update time, and at least a threshold time (e.g., one month) has elapsed since the previous update time.

[0091] Figure 5 is a flowchart exemplarily showing a battery management method according to the second embodiment of the present disclosure. When through Figure 4 the method updates only the first reference current to the n-th reference current I1 to I n the i-th to j-th reference currents I1 to I j , it is possible to use Figure 5 the method to update each remaining reference current. That is, when through Figure 4 the method only charges the battery B in a part of the entire SOC range from S0 to S n (for example, Figure 2 Z1 to S3), it is possible to execute Figure 5 the method. As described above, each of i and j is a natural number, i < j, and i is 2 or greater, or j is less than n.

[0092] In step S510, the control unit 140 calculates the average ratio of the i-th to j-th updated reference currents I 1i to I 1j and the i-th to j-th reference currents I i to I j (see μ in the above equation avg ).

[0093] In step S520, the control unit 140 updates each of the first reference current to the n-th reference current I1 to I n except for the i-th to j-th reference currents I i to I j by multiplying each reference current by the average ratio.

[0094] The embodiments of the present disclosure described above are not implemented only by the apparatus and method, but may be implemented by a program that executes functions corresponding to the configurations of the embodiments of the present disclosure or a recording medium on which the program is recorded, and those skilled in the art can easily implement such implementations from the disclosure of the previously described embodiments.

[0095] While this disclosure has been described above with respect to a limited number of embodiments and accompanying drawings, this disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes can be made to it within the technical aspects of this disclosure and within the equivalent scope of the appended claims.

[0096] Furthermore, without departing from the technical aspects of this disclosure, those skilled in the art can make many substitutions, modifications and changes to the disclosure described above. This disclosure is not limited to the above embodiments and drawings, and some or all of the embodiments can be selectively combined to allow for various modifications.

Claims

1. A battery management system, the battery management system comprising: A sensing unit configured to generate a sensing signal indicating the battery voltage and battery current of the secondary battery; A storage unit configured to store a charging map that records the relationships between a first reference charging state SOC range to an nth reference charging state SOC range, a first reference current to an nth reference current, and a first reference voltage to an nth reference voltage for multi-level constant current charging. as well as A control unit is configured to, in response to a charging start command, begin charging with a constant current using a k-th reference current, the k-th reference current corresponding to the k-th reference SOC range to which the battery's SOC belongs, within the range from the first reference SOC to the n-th reference SOC. The control unit is configured to: In response to the battery voltage reaching a k-th reference voltage corresponding to the k-th reference SOC range before the battery's SOC reaches the upper limit of the k-th reference SOC range during the constant current charging, the charging method is changed from constant current charging to constant voltage charging using the k-th reference voltage. In response to the battery's SOC reaching the upper limit of the k-th reference SOC range during the constant voltage charging period, the k-th reference current of the charging map is updated based on the time series of the battery current during the charging period of the constant voltage charging. Where n is a natural number of 2 or greater, and k is a natural number of n or less.

2. The battery management system according to claim 1, wherein, The control unit is configured to: The average current during the charging period is determined from the time series of the battery current, and The k-th reference current is updated to be equal to the average current.

3. The battery management system according to claim 1, wherein, The control unit is configured to: The average current during the charging period is determined from the time series of the battery current, and The k-th reference current is updated to be equal to the sum of the product of the k-th reference current and the first weight and the product of the average current and the second weight.

4. The battery management system according to claim 3, wherein, Each of the first weight and the second weight is a positive number less than 1, and The sum of the first weight and the second weight is 1.

5. The battery management system according to claim 1, wherein, The control unit is configured to update each remaining reference current from the first reference current to the nth reference current, excluding the kth reference current, based on the updated ratio of the kth reference current to the kth reference current.

6. A battery pack comprising a battery management system according to any one of claims 1 to 5.

7. An electric vehicle comprising the battery pack according to claim 6.

8. A battery management method, the battery management method comprising the following steps: In response to a charging start command, constant current charging is initiated using a k-th reference current corresponding to the k-th reference SOC range to which the SOC of the secondary battery belongs within the first reference charging state range to the nth reference SOC range. The first reference SOC range to the nth reference SOC range is derived from a charging graph that records the interrelationships between the first reference SOC range to the nth reference SOC range, the first reference current to the nth reference current, and the first reference voltage to the nth reference voltage for multi-stage constant current charging. In response to the fact that the battery voltage has reached the kth reference voltage corresponding to the kth reference SOC range before the SOC of the battery reaches the upper limit of the kth reference SOC range during the constant current charging, the constant current charging is changed to constant voltage charging using the kth reference voltage; as well as In response to the battery's SOC reaching the upper limit of the k-th reference SOC range during the constant voltage charging period, the k-th reference current of the charging map is updated based on the time series of the battery current during the charging period of the constant voltage charging. Where n is a natural number of 2 or greater, and k is a natural number of n or less.

9. The battery management method according to claim 8, wherein, The step of updating the k-th reference current of the charging diagram includes: Determine the average current during the charging period from the time series of the battery current; and The k-th reference current is updated to be equal to the average current.

10. The battery management method according to claim 8, wherein, The step of updating the k-th reference current of the charging diagram includes: The average current during the charging period is determined from the time series of the battery current, and The k-th reference current is updated to be equal to the sum of the product of the k-th reference current and the first weight and the product of the average current and the second weight.

11. The battery management method according to claim 10, wherein, Each of the first weight and the second weight is a positive number less than 1, and The sum of the first weight and the second weight is 1.

12. The battery management method according to claim 8, further comprising the following steps: Based on the ratio of the updated k-th reference current to the k-th reference current, update each remaining reference current from the first reference current to the n-th reference current, except for the k-th reference current.

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