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

Abstract

To provide battery management system and method that updates a multi-stage constant current charging map according to the operating condition of a battery.SOLUTION: A battery pack 10 of an electric vehicle 1 includes a sensing unit 110 that generates a sensing signal indicating the battery voltage of a battery B, a memory unit 120 that stores a charging map that records the correspondence between first to nth reference currents for multi-stage constant current charging and first to nth reference voltage ranges, and a control unit 140 that commands a charging circuit 50 connected to the battery to perform constant current charging using a kth reference current corresponding to a kth reference voltage range to which the battery voltage belongs, commands the charging circuit to perform constant voltage charging using the upper limit of the kth reference voltage range in response to the battery voltage reaching an upper limit of the kth reference voltage range during charging, and starts constant current charging using the k+1th reference current corresponding to the k+1th reference voltage range when the battery SOC reaches the upper limit of the kth reference SOC range as a result of constant voltage charging.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technique for controlling the charging of a battery.

[0002] This application claims priority based on Korean Patent Application No. 10-2020-0104883 filed on August 20, 2020, and all of the contents disclosed in the specification and drawings of the corresponding application are incorporated into this application.

Background Art

[0003] Recently, the demand for portable electronic products such as notebook PCs, video cameras, and mobile phones has increased rapidly. As the development of electric vehicles, energy storage batteries, robots, satellites, etc. has become full-scale, research on high-performance batteries capable of repeated charging and discharging has been actively underway.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc. Among these, lithium batteries have attracted attention because they hardly cause a memory effect compared to nickel-based batteries, can be charged and discharged freely, have a very low self-discharge rate, and have a high energy density.

[0005] When charging a battery at a constant current, if the current rate of the charging current is small, a very long time is required to fully charge the battery. On the other hand, if the current rate of the charging current is too high, there is a side effect that the battery degrades quickly.

[0006] One of the charging protocols proposed to solve the above problems is "multi-stage constant-current charging", which gradually adjusts the current rate of the charging current according to the state of charge and voltage of the battery being charged. The current rate is the value obtained by dividing the charging current by the maximum capacity of the battery, and is sometimes referred to as the "C-rate", with the unit "C" being used. The multi-stage constant-current charging map includes at least one data array in which the correspondence between a plurality of voltage ranges and a plurality of current rates is recorded. The charging stage using the multi-stage constant-current charging map is performed by repeating the process in which the charging current at the next sequential current rate is supplied to the battery each time the battery voltage reaches the upper limit of each voltage range.

[0007] As the battery degrades from a new state (BOL: Beginning Of Life), the degradation at the same current rate can accelerate. For example, when performing constant-current charging using the same current rate over a specific voltage range, more lithium deposition is induced as the battery degrades.

[0008] However, charging using a conventional multi-stage constant-current charging map has the problem that it does not consider the operating state (e.g., degradation) of the battery that changes over time. [Prior Art Documents] [Patent Documents] Patent Document 1: US Patent Application Publication No. 2015 / 0340885 Patent Document 2: International Publication No. 2011 / 061902 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] The present invention has been made in view of the above problems, and updates a multi-stage constant current charging map according to the operating state of a battery based on the voltage and current of the battery monitored during charging using the multi-stage constant current charging map. An object is to provide a battery management system, a battery management method, a battery pack, and an electric vehicle.

[0010] Further, even if the charging stage ends without being performed for the entire plurality of voltage ranges, based on the update result for the current rate related to at least one voltage range in which constant current charging has been performed, the remaining voltage ranges in which constant current charging has not been performed Another object is to provide a battery management system, a battery management method, a battery pack, and an electric vehicle that update the current rate related to

[0011] Other objects and advantages of the present invention can be understood from the following description, and will be more clearly understood from the embodiments of the present invention. The objects and advantages of the present invention can be realized by the means and combinations thereof shown in the claims.

Means for Solving the Problems

[0012] A battery management system according to an aspect of the present invention includes a sensing unit that generates a sensing signal indicating a battery voltage of a battery, first to nth reference currents for multi-stage constant current charging, and first to nth reference voltage ranges. A memory unit that stores a charging map in which the correspondence relationship is recorded, and commands constant current charging using the kth reference current corresponding to the kth reference voltage range to which the battery voltage belongs in a charging circuit connected to the battery, and during the constant current charging, in response to the battery voltage reaching the upper limit of the kth reference voltage range, commands constant voltage charging using the upper limit of the kth reference voltage range to the charging circuit, and when the SOC of the battery reaches the upper limit of the kth reference SOC range by the constant voltage charging, starts constant current charging using the (k + 1)th reference current corresponding to the (k + 1)th reference voltage range. And a control unit. The kth reference voltage is the voltage that is the upper limit of the kth reference voltage range.

[0013] The k-th reference voltage may be lower than the start voltage of the (k + 1)-th reference voltage range. After starting constant current charging using the (k + 1)-th reference current corresponding to the (k + 1)-th reference voltage range, the control unit can switch from the constant current charging to constant voltage charging using the (k + 1)-th reference voltage in response to the voltage of the battery reaching the upper limit of the (k + 1)-th reference voltage range. The (k + 1)-th reference voltage may be the voltage when the voltage of the battery reaches the upper limit of the (k + 1)-th reference voltage range.

[0014] The control unit may be configured to update the charging map based on a k-th measured voltage curve and a k-th reference voltage curve indicating the correspondence between the battery voltage and the battery SOC over the charging period of the constant current charging using the k-th reference current.

[0015] The control unit may be configured to update the k-th reference current based on the ratio of the average SOC of the k-th measured voltage curve to the average SOC of the k-th reference voltage curve.

[0016] The control unit may be configured to update the k-th reference current based on the ratio of the average voltage of the k-th measured voltage curve to the average voltage of the k-th reference voltage curve.

[0017] The control unit may be configured to update the k-th reference current based on a first ratio of the average SOC of the k-th measured voltage curve to the average SOC of the k-th reference voltage curve and a second ratio of the average voltage of the k-th measured voltage curve to the average voltage of the k-th reference voltage curve.

[0018] The control unit may be configured to update the k-th reference current based on the ratio of the interested SOC to the k-th reference SOC. The interested SOC may be the SOC of the battery when the battery voltage reaches the upper limit of the k-th reference voltage range.

[0019] The control unit may be configured to update each of the remaining reference currents excluding the k-th reference current based on the ratio of the updated k-th reference current to the k-th reference current.

[0020] In addition, a battery pack according to another aspect of the present invention includes the battery management system. An electric vehicle according to still another aspect of the present invention includes the battery pack.

[0021] A battery management method according to still another aspect of the present invention includes: based on a charge map in which a correspondence relationship between first to n-th reference currents and first to n-th reference voltage ranges for multi-stage constant current charging is recorded, instructing constant current charging using a k-th reference current corresponding to a k-th reference voltage range to which a battery voltage of a battery connected to a charging circuit belongs; during the constant current charging, in response to the battery voltage reaching an upper limit of the k-th reference voltage range, instructing constant voltage charging using the upper limit of the k-th reference voltage range to the charging circuit, and when the SOC of the battery reaches an upper limit of a k-th reference SOC range by the constant voltage charging, starting constant current charging using a (k + 1)-th reference current corresponding to a (k + 1)-th reference voltage range. The k-th reference voltage is a voltage that is an upper limit of the k-th reference voltage range.

[0022] The k-th reference voltage may be lower than a start voltage of the (k + 1)-th reference voltage range. The battery management method may further include, after starting constant current charging using a (k + 1)-th reference current corresponding to the (k + 1)-th reference voltage range, switching from the constant current charging to constant voltage charging using a (k + 1)-th reference voltage in response to the battery voltage reaching an upper limit of the (k + 1)-th reference voltage range. The (k + 1)-th reference voltage may be a voltage when the battery voltage reaches an upper limit of the (k + 1)-th reference voltage range. The battery management method may further include updating the charging map by comparing a k-th measured voltage curve indicating a correspondence relationship between the battery voltage and the SOC of the battery over a charging period of the constant current charging using the k-th reference current with a k-th reference voltage curve in response to the battery voltage reaching the upper limit of the k-th reference voltage range. The step of updating the charging map may update the k-th reference current based on a ratio of an average SOC of the k-th measured voltage curve to an average SOC of the k-th reference voltage curve.

Advantages of the Invention

[0023] According to at least one of the embodiments of the present invention, the multi-stage constant current charging map can be updated according to the operating state of the battery based on the voltage and current of the battery monitored during charging using the multi-stage constant current charging map.

[0024] Also, according to at least one of the embodiments of the present invention, even if the charging stage ends without being performed for the entire plurality of voltage ranges, based on the update result for the current rate related to at least one voltage range in which the constant current charging is performed, the current rate related to the remaining voltage ranges in which the constant current charging is not performed can be updated.

[0025] The effects of the present invention are not limited to the effects described above, and other effects of the present invention not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0026] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventor himself must interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that he can appropriately define the concept of the terms in order to explain the invention in the best way.

[0029] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there may be various equivalents and modifications that can replace them at the time of this application.

[0030] Terms including ordinal numbers such as first, second, etc. are used for the purpose of distinguishing any one of various components from the rest, and the components are not limited by such terms.

[0031] Throughout the specification, when a part states that a certain component "includes" something, this means that, unless otherwise stated to the contrary, it does not exclude other components but may further include other components. Also, terms such as "control unit" described in the specification indicate a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0032] Furthermore, throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where it is "directly connected", but also the case where it is "indirectly connected" via other elements in between.

[0033] FIG. 1 is a diagram illustrating the configuration of the electric vehicle 1 according to the present invention.

[0034] Referring to FIG. 1, the electric vehicle 1 includes a battery pack 10, an inverter 30, an electric motor 40, and a charging circuit 50.

[0035] The battery pack 10 includes a battery B, a switch 20, and a battery management system 100.

[0036] The battery B includes at least one battery cell. The type of each battery cell is not particularly limited as long as it can be repeatedly charged and discharged, such as a lithium-ion cell, for example. The battery B can be coupled to the inverter 30 and / or the charging circuit 50 through a pair of power terminals provided in the battery pack 10.

[0037] Switch 20 is connected in series to battery B. Switch 20 is provided in the current path for charging and discharging battery B. Switch 20 is on-off controlled according to a switching signal from battery management system 100. Switch 20 can be a mechanical relay that is turned on and off by the magnetic force of a coil, or a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect transistor).

[0038] Inverter 30 is provided to convert the direct current from battery B into an alternating current according to an instruction from battery management system 100. Electric motor 40 can be, for example, a three-phase alternating current motor. Electric motor 40 is driven using the alternating current power from inverter 30.

[0039] Battery management system 100 can be in charge of overall control related to the charging and discharging of battery B.

[0040] Battery management system 100 includes sensing unit 110, memory unit 120, and control unit 140. Battery management system 100 can further include at least one of interface unit 130 and switch driver 150.

[0041] Sensing unit 110 includes voltage sensor 111 and current sensor 112. Sensing unit 110 can further include temperature sensor 113.

[0042] Voltage sensor 111 is connected in parallel to battery B, configured to detect the battery voltage applied across both ends of battery B, and generate a voltage signal indicating the detected battery voltage. Current sensor 112 is connected in series to battery B through the 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.

[0043] The memory unit 120 may include a storage medium of at least one type among flash memory (registered trademark) type, hard disk type, SSD type (Solid State Disk type), SDD type (Silicon Disk Drive type), multimedia card micro type, RAM (random access memory), SRAM (static random access memory), ROM (read-only memory), EEPROM (electrically erasable programmable read-only memory), and PROM (programmable read-only memory). The memory unit 120 may store data and programs required for the arithmetic operation by the control unit 140. The memory unit 120 may store data indicating the result of the arithmetic operation by the control unit 140.

[0044] The memory unit 120 stores a charging map. The charging map may be pre-stored in the memory unit 120 before the shipment of the battery management system 100, or may be received from the outside (for example, battery manufacturer) or the upper controller 2 via the interface unit 130. The data recorded in the charging map may be predetermined based on the test and / or simulation results for the battery sample with the same specifications as the battery B.

[0045] The charging map is used for the charging stages of the multi-stage constant current charging of the battery B. In the charging map, the correspondence relationships of (i) the first to nth reference currents, (ii) the first to nth reference voltage ranges, (iii) the first to nth reference SOCs, and (iv) the first to nth reference voltage curves for the multi-stage constant current charging are recorded. n is a natural number of 2 or more. The subsequent reference currents may be smaller than the previous reference currents. Each reference voltage range can be referred to as a "stage".

[0046] The interface unit 130 may include a communication circuit configured to assist in wired or wireless communication between the control unit 140 and the upper controller 2 (for example, ECU: Electronic Control Unit). The wired communication is, for example, CAN (controller area network) communication, and the wireless communication may be, for example, ZigBee (registered trademark) or Bluetooth (registered trademark) communication. Of course, as long as it can assist in the wired or wireless communication between the control unit 140 and the upper controller 2, the type of communication protocol is not particularly limited. The interface unit 130 may include an output device (for example, a display, a speaker) that provides the information received from the control unit 140 and / or the upper controller 2 in a form recognizable by the user. The upper controller 2 may control the inverter 30 based on the battery information (for example, voltage, current, temperature, SOC) collected through communication with the battery management system 100. The upper controller 2 may transmit a charging start command or a charging interruption command to the battery management system 100 according to the input of the vehicle user.

[0047] The control unit 140 may be operably coupled to the upper controller 2, the switch 20, the charging circuit 50, the sensing unit 110, the memory unit 120, the interface unit 130 and / or the switch driver 150. The fact that two components are operably coupled means that the two components are directly or indirectly connected so as to be able to transmit and receive signals in one direction or two directions.

[0048] The switch driver 150 is electrically coupled to the control unit 140 and the switch 20. The switch driver 150 is configured to selectively turn on and off the switch 20 in response to an instruction from the control unit 140. The control unit 140 may instruct the switch driver 150 to turn on the switch 20 during the progress of the charging stage.

[0049] The control unit 140 may collect a sensing signal from the sensing unit 110. The sensing signal refers to a synchronously detected voltage signal, current signal, and / or temperature signal.

[0050] The control unit 140, also referred to as the "battery controller", may be implemented in hardware using at least one of an ASIC (application specific integrated circuit), DSP (digital signal processor), DSPD (digital signal processing device), PLD (programmable logic device), FPGA (field programmable gate array), microprocessor, and other electrical units for performing functions.

[0051] The interface unit 130 can relay two-way communication between the control unit 140 and the charging circuit 50 and two-way communication between the control unit 140 and the upper controller 2. The charging circuit 50 is configured to supply a charging current at a current rate requested from the battery management system 100 to the battery B. The charging circuit 50 may be configured to supply a charging voltage having a voltage level requested from the battery management system 100 to the battery B. The control unit 140 is configured to start a charging stage using a charging map in response to receiving a charging start command via the interface unit 130. The control unit 140 may end the charging stage using the charging map in response to receiving a charging interruption command via the interface unit 130.

[0052] The control unit 140 may determine a SOC (State Of Charge) indicating the remaining capacity of the battery B based on a sensing signal. In determining the SOC, known algorithms such as ampere counting, OCV (open circuit voltage)-SOC curve, and Kalman filter may be used. The SOC of the battery B may be referred to as "battery SOC".

[0053] FIG. 2 is a diagram illustrating the correspondence between the reference current and the reference voltage range recorded in the charging map, and FIG. 3 is a diagram illustrating the correspondence between the reference voltage range and the reference SOC recorded in the charging map. For convenience of explanation, in FIGS. 2 and 3, n = 4, that is, it is shown that the charging map defines the correspondence between four reference currents, four reference voltage ranges, and four reference SOCs.

[0054] The current profile 210 shown in FIG. 2 shows the correspondence between the first to fourth reference currents I1 to I4 and the first to fourth reference voltage ranges ΔV1 to ΔV4 for a battery B in a new state. The current profile 210 may be recorded in the charging map in a format such as a data table. When k (which may be referred to as a "charging index") is a natural number not exceeding n, V k-1 and V k are the k-th reference voltage ranges ΔV kare the lower limit and the upper limit.

[0055] The first to fourth reference voltage ranges ΔV1 to ΔV4 are sequentially continuous. Thus, when i is a natural number less than or equal to n - 1, V i is the upper limit of the ith reference voltage range ΔV i and is also the lower limit of the (i + 1)th reference voltage range ΔV i+1 . For example, the upper limit of ΔV2 and the lower limit of ΔV3 are both the same, V2. Hereinafter, V k may be referred to as the "kth reference voltage".

[0056] When the battery voltage of the battery B is within the ith reference voltage range ΔV i , the control unit 140 may command the charging circuit 50 to perform constant current charging using the ith reference current I i .

[0057] During the constant current charging using the ith reference current I i , when the SOC of the battery B reaches the upper limit V i of the ith reference voltage range ΔV i , the control unit 140 may command the charging circuit 50 to perform constant current charging using the (i + 1)th reference current I i+1 . That is, the control unit 140 may switch from the constant current charging using the ith reference current I i to the constant current charging using the (i + 1)th reference current I i+1 .

[0058] During the constant current charging using the nth reference current I n , when the SOC of the battery B reaches the upper limit V n of the nth reference voltage range ΔV n , the control unit 140 ends the multi-stage constant current charging using the charging map and may command the charging circuit 50 to perform constant voltage charging using the upper limit V n . That is, the control unit 140 may switch from the constant current charging using the nth reference current I n to the constant voltage charging using the upper limit V n .

[0059] The first voltage profile 310 shown in FIG. 3 shows the correspondence between the first to fourth reference SOCs S1 to S4 and the first to fourth reference voltage ranges ΔV1 to ΔV4 for a battery B in a new state. The first voltage profile 310 can be recorded in a charging map in a format such as a data table. The first voltage profile 310 includes first to fourth reference voltage curves. The k-th reference voltage curve is the part corresponding to the k-th reference voltage range ΔV k in the first voltage profile 310.

[0060] S k represents the SOC of the battery B in the new state when the battery voltage of the battery B reaches the k-th reference voltage V k by constant current charging using the k-th reference current I k .

[0061] On the other hand, as the battery B gradually deteriorates, the capacity loss of the battery B increases, so the amount of voltage rise due to the same charging capacity increases compared to the new state. As a result, during constant current charging using the k-th reference current I k of the charging map, before the SOC reaches the k-th reference SOC S k , the fact that the battery voltage reaches the k-th reference voltage V k indicates that the battery B has deteriorated compared to the new state. The second voltage profile 320 shown in FIG. 3 shows the correspondence between the change history of the battery voltage and the change history of the SOC monitored through the process of constant current charging of the deteriorated battery B by sequentially using the first to fourth reference currents I1 to I4 for the first to fourth reference voltage ranges ΔV1 to ΔV4 without applying the battery management method according to the present invention (see FIG. 4). Referring to the second voltage profile 320, Z k is the battery SOC when the battery voltage of the deteriorated battery B reaches the k-th reference voltage V k , and it can be confirmed that it is smaller than the k-th reference SOC S k . That is, S1>Z1, S2>Z2, S3>Z3, S4>Z4.

[0062] The k-th reference current Ik During constant current charging using, before the SOC of battery B reaches the k-th reference SOC S k , if the battery voltage reaches the k-th reference voltage V k , it indicates that it is necessary to decrease the k-th reference current I k in the next multi-stage constant current charging stage. Considering the voltage history and / or SOC history monitored during charging with the k-th reference current I k , the degree of decrease of the k-th reference current I k can be determined.

[0063] The third voltage profile 330 shown in FIG. 3 shows the correspondence between the change history of the battery voltage and the change history of the SOC monitored through the process of charging the degraded battery B by applying the battery management method according to the present invention (see FIG. 4). The third voltage profile 330 includes first to fourth measured voltage curves. The k-th measured voltage curve is the part corresponding to the k-th reference voltage range ΔV k in the third voltage profile 330.

[0064] Referring to the third voltage profile 330, the control unit 140 monitors the battery voltage, battery current, and SOC every set time (for example, 0.001 seconds) during constant current charging using the k-th reference current I k . In response to the battery voltage reaching the k-th reference voltage V k before the SOC of battery B reaches the k-th reference SOC S k , the control unit 140 can switch from constant current charging using the k-th reference current I k to constant voltage charging using the k-th reference voltage V k . Thereby, from the time when the battery voltage reaches the k-th reference voltage V k until the SOC of battery B reaches the k-th reference SOC S k , battery B is at the k-th reference voltage V kIt is charged at a constant voltage. For example, after constant current charging is performed using the second reference current I2 over the voltage range of V1 to V2, the battery B is charged at a constant voltage equal to the k-th reference voltage V2 until the SOC of the battery B reaches the second reference SOC S2. During the constant voltage charging using the k-th reference voltage range ΔV k while the battery voltage gradually increases, the battery current gradually decreases. The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV k while the battery voltage gradually increases, the battery current gradually decreases. The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV

[0065] The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV k Based on the battery voltage, battery current, and SOC monitored during the charging over the k-th reference voltage range ΔV, the k-th reference current I of the charging map including the current profile 210 in FIG. 2 and the first voltage profile 310 in FIG. 3 k can be updated. The current I of the current profile 230 in FIG. 2 11 ~I 14 can each be the result of updating the reference currents I1 to I4 of the charging map.

[0066] Specifically, the control unit 140 can determine at least one of the average voltage and the average SOC of the k-th reference voltage curve. The average voltage of the k-th reference voltage curve is the average of the battery voltages over the k-th reference voltage range ΔV in the first voltage profile 310. The average SOC of the k-th reference voltage curve is the average of the SOCs over the k-th reference voltage range ΔV in the first voltage profile 310. k while the battery voltage gradually increases, the battery current gradually decreases. The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV k while the battery voltage gradually increases, the battery current gradually decreases. The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV

[0067] The control unit 140 can determine at least one of the average voltage and the average SOC of the k-th measured voltage curve. The average voltage of the k-th measured voltage curve is the average of the battery voltages over the k-th reference voltage range ΔV in the third voltage profile 330. The average SOC of the k-th measured voltage curve is the average of the SOCs over the k-th reference voltage range ΔV in the third voltage profile 330. k while the battery voltage gradually increases, the battery current gradually decreases. The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV k while the battery voltage gradually increases, the battery current gradually decreases. The control unit 140 can monitor the battery voltage, battery current, and SOC every set time during the constant voltage charging using the k-th reference voltage range ΔV

[0068] Subsequently, the control unit 140 determines the k-th reference current I of the charging map based on at least one of the average voltage and the average SOC of the k-th reference voltage curve and at least one of the average voltage and the average SOC of the k-th measured voltage curve. k and can update it.

[0069] The control unit 140 can update the k-th reference current I based on a first ratio (less than 1) of the average SOC of the k-th measured voltage curve to the average SOC of the k-th reference voltage curve. k For example, the control unit 140 can update the k-th reference current I to be the same as the product of the first ratio and the k-th reference current I. k k and can update it.

[0070] Alternatively, the control unit 140 can update the k-th reference current I based on a second ratio (less than 1) of the average voltage of the k-th reference voltage curve to the average voltage of the k-th measured voltage curve. k For example, the control unit 140 can update the k-th reference current I to be the same as the product of the second ratio and the k-th reference current I. k k and can update it.

[0071] Alternatively, the control unit 140 can update the k-th reference current I based on the first ratio and the second ratio. k For example, the control unit 140 can update the k-th reference current I to be the same as the product of the first ratio, the second ratio, and the k-th reference current I. k k and can update it.

[0072] Alternatively, the control unit 140 can update the k-th reference current I based on a third ratio (less than 1) of the SOC of interest to the k-th reference SOC S. k For example, the control unit 140 can update the k-th reference current I to be the same as the product of the third ratio and the k-th reference current I. k k The SOC of interest is the SOC at which the battery voltage is the k-th reference voltage V. k k ​​​​​The SOC U of the battery B when reaching k may be the same.

[0073] On the other hand, in the charging stage according to the battery management method described above, it is frequent that the charging is not performed for some of the reference voltage ranges ΔV1 to ΔV4. For example, referring to FIGS. 2 and 3, when the charging stage using the charging map is started when the battery voltage is higher than V0, the first measured voltage curve over the entire first reference voltage range ΔV1 cannot be obtained, so the first reference current I1 cannot be updated by the method described above. In another example, when the vehicle user separates the charging cable from the electric vehicle 1 before the battery voltage reaches V4, the fourth measured voltage curve over the entire fourth reference voltage range ΔV4 cannot be obtained, so the fourth reference current I4 cannot be updated.

[0074] To solve the above problems, when charging is started when the battery voltage is greater than V0 or when charging ends when the battery voltage is less than V4, the control unit 140 can update the reference currents related to the remaining reference voltage ranges based on the update information for at least one reference voltage range in which the measured voltage curve is obtained among all the reference voltage ranges ΔV1 to ΔV4.

[0075] The k-th reference voltage range ΔV k and the corresponding k-th reference current I k are only updated to I 1k by the battery management method described above. Assume that. The control unit 140 can update the remaining reference currents based on the determined ratio after determining the ratio of I k to I 1k . For example, when the second reference current I2 is updated from 120 A to 100 A, the control unit 140 multiplies the first reference current I1, the third reference current I3, and the fourth reference current I4 by 100 / 120 = 5 / 6 respectively, and can update the first reference current I1, the third reference current I3, and the fourth reference current I4.

[0076] Assume that i and j are each natural numbers, i ≤ j, i is 2 or more, and j is less than n = 4. The i-th to j-th reference voltage ranges ΔV i ~ΔV j corresponding to the i-th to j-th reference currents I i ~I j alone can have the charging stage end while remaining updated to I 1i ~I 1j respectively. Then, the control unit 140 can update each of the remaining reference currents using the following formula. <Formula>

Number

[0077] In the above formula, x is a natural number less than or equal to n excluding i to j, I x is the reference current before update, and I<on 1x is the updated reference current. μ avg is the ratio of the average of the i-th to j-th updated reference currents I i ~I j to the i-th to j-th reference currents I 1i ~I 1j .

[0078] In an example, when i = 2, j = 3, n = 4, i1 = 150A, i2 = 120A, i3 = 110A, i4 = 90A, i 12 = 100A, i 13 = 95A, then i 11 = i1 × 1 / (3 - 2 + 1) × {i 12 / i2 + i 13 / i3} A = i1 × 1 / 2 × {100 / 120 + 95 / 110} A ≒ 127A, and i 14 = i4 × 1 / (3 - 2 + 1) × {i 12 / i2 + i 13 / i3} A = i4 × 1 / 2 × {100 / 120 + 95 / 110} A ≒ 76A.

[0079] FIG. 4 is a flowchart illustrating a battery management method according to a first embodiment of the present invention. The method of FIG. 4 can be started in response to a charging start command from a vehicle user.

[0080] Referring to FIGS. 1 to 4, in step S410, the control unit 140 determines the k-th reference current I k corresponding to the k-th reference voltage range ΔV k to which the battery voltage of the battery B belongs from the charging map. For example, when the battery voltage is equal to or higher than V1 and lower than V2, the second reference current I2 is selected.

[0081] In step S420, the control unit 140 commands the charging circuit 50 to perform constant current charging using the k-th reference current I k . As a result, the charging circuit 50 supplies the battery B with the k-th reference current I k as a charging current to start constant current charging using the k-th reference current I k .

[0082] In step S430, the control unit 140 determines whether the battery voltage reaches the k-th reference voltage V k before the battery SOC reaches the k-th reference SOC S k . If the value in step S440 is "yes", the process proceeds to step S450. If the value in step S430 is "no", step S430 is performed again after a predetermined time.

[0083] In step S440, the control unit 140 commands the charging circuit 50 to perform constant voltage charging using the k-th reference voltage V k . As a result, the charging circuit 50 ends constant current charging using the k-th reference current I k and supplies the battery B with the same charging voltage as the k-th reference voltage V k .

[0084] In step S450, the control unit 140 determines that the battery SOC is the k-th reference SOC S k ​​​​Determine whether it has reached. If the value of step S450 is "Yes", proceed to step S460. If the value of step S450 is "No", step S450 is performed again after a predetermined time.

[0085] In step S460, the control unit 140 determines the k-th measured voltage curve. The k-th measured voltage curve shows the correspondence between the battery voltage and the battery SOC over the charging period of constant current charging using the k-th reference current I k is used.

[0086] In step S470, the control unit 140 determines whether the voltage range of the k-th measured voltage curve is the same as the k-th reference voltage range ΔV k or not. If the value of step S470 is "Yes", proceed to step S480. If the value of step S470 is "No", proceed to step S490. For example, when the battery voltage is greater than V0 and less than V1 and then constant current charging is performed with the first reference current I1, the value of step S470 becomes "No".

[0087] In step S480, the control unit 140 updates the charging map based on the k-th reference voltage curve and the k-th measured voltage curve.

[0088] In step S490, the control unit 140 determines whether the charging index k is the same as n. That is, the control unit 140 determines whether the charging for the last reference voltage range ΔV n specified by the charging map is completed. If the value of step S490 is "No", after increasing the charging index k by 1 in step S492, return to step S430. If the value of step S490 is "Yes", the method in FIG. 4 ends.

[0089] The method of FIG. 4 can be started in response to a charging start command when a predetermined update condition is satisfied. The update condition is for preventing the charging maps 210 and 310 from being updated too frequently in vain. For example, it can be indicated that the degradation degree of the battery B has increased above a certain level, such as the accumulated capacity of the battery B has increased by more than a first critical value (e.g., 100 Ah [ampere - hour]) compared to the accumulated capacity at the time of the previous update, the number of cycles of the battery B has increased by more than a second critical value (e.g., 50 times) compared to the number of cycles at the time of the previous update, the capacity retention rate of the battery B has decreased by more than a third critical value (e.g., 5%) compared to the capacity retention rate at the time of the previous update, a result of more than a critical time (e.g., one month) has passed since the previous update, and so on.

[0090] FIG. 5 is a flowchart illustrating a battery management method according to a second embodiment of the present invention. The method of FIG. 5 can be used to update each of the remaining reference currents when only the i - th to j - th reference currents I n among the first to n - th reference currents I1 to I i ~I j are updated by the method of FIG. 4. That is, the method of FIG. 5 can be performed when the battery B is charged only for a part of the voltage range from V0 to V n . As described above, i and j are natural numbers respectively, i < j, i is 2 or more, or j is less than n (e.g., 4).

[0091] In step S510, the control unit 140 calculates the average ratio of the i - th to j - th updated reference currents I i ~I j for the i - th to j - th reference currents I 1i ~I 1j (refer to μ avg in the above formula).

[0092] In step S520, the control unit 140 determines the first to n - th reference currents I1 to I nAmong them, the average ratio is multiplied by the remaining reference currents excluding the i-th to j-th reference currents I i ~I j respectively, and the remaining reference currents are updated respectively.

[0093] The embodiments of the present invention described above are not necessarily implemented through the apparatus and method, but may be implemented through a program that realizes the functions corresponding to the configurations of the embodiments of the present invention or a recording medium on which the program is recorded. Such an implementation should be easily achievable by those skilled in the technical field to which the present invention pertains from the description of the above-described embodiments.

[0094] As described above, the present invention has been described with reference to the limited embodiments and drawings, but the present invention is not limited thereto. It goes without saying that various modifications and variations are possible within the equivalent scope of the technical idea and claims of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains.

[0095] In addition, the above-described present invention can be variously substituted, modified, and changed within the scope not departing from the technical idea of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains. Therefore, it is not limited by the above-described embodiments and the attached drawings, and all or part of each embodiment can be selectively combined to be configured so that various modifications can be made.

Claims

1. A sensing unit that generates a sensing signal indicating the battery voltage of a battery; A memory unit that stores a charging map in which the correspondence between the first to nth reference currents and the first to nth reference voltage ranges for multi-stage constant current charging is recorded; Instructs the charging circuit connected to the battery to perform constant current charging using the kth reference current corresponding to the kth reference voltage range to which the battery voltage belongs; During the constant current charging, in response to the battery voltage reaching the upper limit of the kth reference voltage range, instructs the charging circuit to perform constant voltage charging using the upper limit of the kth reference voltage range, and when the SOC of the battery reaches the upper limit of the kth reference SOC range by the constant voltage charging, starts constant current charging using the (k + 1)th reference current corresponding to the (k + 1)th reference voltage range, a control unit; A battery management system.

2. The battery management system according to claim 1, wherein the kth reference voltage, which is the voltage that is the upper limit of the kth reference voltage range, is lower than the start voltage of the (k + 1)th reference voltage range.

3. The control unit, After starting constant current charging using the (k + 1)th reference current corresponding to the (k + 1)th reference voltage range, in response to the battery voltage reaching the upper limit of the (k + 1)th reference voltage range, switches from the constant current charging to constant voltage charging using the (k + 1)th reference voltage; The battery management system according to claim 1, wherein the (k + 1)th reference voltage is the voltage when the battery voltage reaches the upper limit of the (k + 1)th reference voltage range.

4. The control unit, Updates the charging map based on the kth measured voltage curve and the kth reference voltage curve indicating the correspondence between the battery voltage and the battery SOC over the charging period of the constant current charging using the kth reference current, according to the battery management system of claim 1.

5. The control unit, Updates the kth reference current based on the ratio of the average SOC of the kth measured voltage curve to the average SOC of the kth reference voltage curve, according to the battery management system of claim 4.

6. The control unit, Updates the kth reference current based on the ratio of the average voltage of the kth measured voltage curve to the average voltage of the kth reference voltage curve, according to the battery management system of claim 4.

7. The control unit, Updating the k-th reference current based on a first ratio of an average SOC of the k-th measured voltage curve to an average SOC of the k-th reference voltage curve and a second ratio of an average voltage of the k-th reference voltage curve to an average voltage of the k-th measured voltage curve, the battery management system according to claim 4.

8. The control unit updates the k-th reference current based on a ratio of an SOC of interest to the k-th reference SOC, wherein the SOC of interest is the SOC of the battery when the battery voltage reaches the upper limit of the k-th reference voltage range, the battery management system according to claim 4.

9. The control unit updates each of the remaining reference currents excluding the k-th reference current based on a ratio of the updated k-th reference current to the k-th reference current, the battery management system according to claim 4.

10. A battery pack including the battery management system according to any one of claims 1 to 9.

11. An electric vehicle including the battery pack according to claim 10.

12. Based on a charging map in which a correspondence relationship between first to n-th reference currents and first to n-th reference voltage ranges for multi-stage constant current charging is recorded, commanding a constant current charging using the k-th reference current corresponding to the k-th reference voltage range to which the battery voltage of the battery belongs to a charging circuit connected to the battery; and during the constant current charging, in response to the battery voltage reaching the upper limit of the k-th reference voltage range, commanding a constant voltage charging using the upper limit of the k-th reference voltage range to the charging circuit, and when the SOC of the battery reaches the upper limit of the k-th reference SOC range by the constant voltage charging, starting a constant current charging using the (k + 1)-th reference current corresponding to the (k + 1)-th reference voltage range, including A battery management method.

13. The k-th reference voltage, which is the voltage that is the upper limit of the k-th reference voltage range, is lower than the start voltage of the (k + 1)-th reference voltage range, the battery management method according to claim 12.

14. After starting the constant current charging using the (k + 1)-th reference current corresponding to the (k + 1)-th reference voltage range, further including switching from the constant current charging to a constant voltage charging using the (k + 1)-th reference voltage in response to the battery voltage reaching the upper limit of the (k + 1)-th reference voltage range The battery management method according to claim 12, wherein the (k + 1)-th reference voltage is the voltage when the voltage of the battery reaches the upper limit of the (k + 1)-th reference voltage range.

15. The battery management method according to claim 12, further comprising a step of updating the charging map by comparing a k-th measured voltage curve showing a correspondence relationship between the battery voltage and the SOC of the battery over a charging period of the constant current charging using the k-th reference current with a k-th reference voltage curve in response to the battery voltage reaching the upper limit of the k-th reference voltage range.

16. The step of updating the charging map includes: The battery management method according to claim 15, wherein the k-th reference current is updated based on a ratio of an average SOC of the k-th measured voltage curve to an average SOC of the k-th reference voltage curve.

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