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

Abstract

To provide a battery management system for updating a multistage constant current charging map based on a battery voltage and a battery current monitored during charging using the multistage constant current charging map, a battery management method, a battery pack, and an electric vehicle.SOLUTION: A method starts constant current charging using a k-th reference current corresponding to a k-th reference SOC range to which a SOC of a battery belongs among first to n-th reference SOC ranges in response to a charging start command, switches from the constant current charging to constant voltage charging using a k-th reference voltage in response to the battery voltage reaching the k-th reference voltage corresponding to the k-th reference SOC range, and starts the constant current charging using a (k+1)-th reference current corresponding to a (k+1)-th reference SOC range among the first to n-th reference SOC ranges when the SOC of the battery reaches an upper limit value of the k-th reference SOC range.SELECTED DRAWING: Figure 4

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. 10-2020-0101934 filed on August 13, 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 have almost no 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 current rates and a plurality of SOC (State of Charge) ranges 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-order current rate is supplied to the battery each time the SOC of the battery reaches the upper limit value of each SOC range.

[0007] As the battery degrades from the new state (BOL: Beginning Of Life), the degradation at the same current rate can accelerate.

[0008] However, charging using the conventional multi-stage constant-current charging map has the problem that it does not consider battery degradation.

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 an object thereof is to provide a battery management system, a battery management method, a battery pack, and an electric vehicle that update a multi-stage constant-current charging map based on a battery voltage and a battery current monitored during charging using the multi-stage constant-current charging map.

[0010] Further, another object of the present invention is to provide a battery management system, a battery management method, a battery pack, and an electric vehicle that update the current rate of each of the remaining SOC ranges among a plurality of SOC ranges based on the update result for the current rate of a part of the SOC ranges, even if the charging stage ends while being performed only for a part of the plurality of SOC ranges.

[0011] Other objects and advantages of the present invention will be understood from the following description and will be more clearly understood by the embodiments of the present invention. Also, 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 voltage sensor for measuring a battery voltage, a current sensor for measuring a battery current, a memory unit that stores a charging map in which a correspondence relationship between first to nth reference SOC ranges and first to nth reference currents for multi-stage constant current charging is recorded, and in response to a charging start command, starts constant current charging using a kth reference current corresponding to a kth reference SOC range to which the SOC of the battery belongs among the first to nth reference SOC ranges, and during the constant current charging, in response to the battery voltage reaching a kth reference voltage corresponding to the kth reference SOC range before the SOC of the battery reaches the upper limit value of the kth reference SOC range, switches from the constant current charging to constant voltage charging using the kth reference voltage, and when the SOC of the battery reaches the upper limit value of the kth reference SOC range during the constant voltage charging, starts constant current charging using a (k + 1)th reference current corresponding to a (k + 1)th reference SOC range among the first to nth reference SOC ranges. The kth reference voltage is the voltage when the SOC of the battery reaches the upper limit value of the kth reference SOC range in the voltage data corresponding to the kth reference SOC range.

[0013] The kth reference voltage may be higher than the start voltage of the (k + 1)th reference SOC range.

[0014] After starting the constant current charging using the (k + 1)-th reference current corresponding to the (k + 1)-th reference SOC range, when the battery voltage reaches the (k + 1)-th reference voltage corresponding to the (k + 1)-th reference SOC range before the SOC of the battery reaches the upper limit value of the (k + 1)-th reference SOC range, the control unit can switch from the constant current charging to the constant voltage charging using the (k + 1)-th reference voltage. The (k + 1)-th reference voltage can be the voltage when the SOC of the battery reaches the upper limit value of the (k + 1)-th reference SOC range in the voltage data corresponding to the (k + 1)-th reference SOC range.

[0015] The control unit can be configured to update the k-th reference current of the charging map based on the current history of the battery current during the charging period of the constant voltage charging.

[0016] The control unit can be configured to determine the average current during the charging period based on the current history and update the k-th reference current based on the average current.

[0017] The control unit can be configured to determine the average current during the charging period based on the current history and update the k-th reference current based on the sum of the product of the k-th reference current and the first weighting value and the product of the average current and the second weighting value. The first weighting value and the second weighting value can each be a positive number less than 1. The sum of the first weighting value and the second weighting value can be 1.

[0018] The control unit can 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.

[0019] Note that the battery pack according to another aspect of the present invention includes the battery management system.

[0020] The electric vehicle according to another aspect of the present invention includes the battery pack. The battery management method according to another aspect of the present invention includes: a step of reading a charging map in which a correspondence relationship between first to nth reference SOC ranges for multi-stage constant current charging and first to nth reference currents is recorded in response to a charging start command; a step of starting constant current charging using a kth reference current corresponding to a kth reference SOC range to which the SOC of the battery belongs among the first to nth reference SOC ranges; a step of switching from the constant current charging to constant voltage charging using the kth reference voltage in response to the battery voltage reaching the kth reference voltage corresponding to the kth reference SOC range before the SOC of the battery reaches the upper limit value of the kth reference SOC range during the constant current charging; and a step of starting constant current charging using a (k + 1)th reference current corresponding to a (k + 1)th reference SOC range among the first to nth reference SOC ranges when the SOC of the battery reaches the upper limit value of the kth reference SOC range during the constant voltage charging. The kth reference voltage is the voltage when the SOC of the battery reaches the upper limit value of the kth reference SOC range in the voltage data corresponding to the kth reference SOC range. The kth reference voltage may be higher than the start voltage of the (k + 1)th reference SOC range.

[0021] The battery management method may further include a step of switching from the constant current charging to constant voltage charging using the (k + 1)th reference voltage in response to the battery voltage reaching the (k + 1)th reference voltage corresponding to the (k + 1)th reference SOC range before the SOC of the battery reaches the upper limit value of the (k + 1)th reference SOC range after starting constant current charging using the (k + 1)th reference current corresponding to the (k + 1)th reference SOC range. The (k + 1)th reference voltage may be the voltage when the SOC of the battery reaches the upper limit value of the (k + 1)th reference SOC range in the voltage data corresponding to the (k + 1)th reference SOC range. The battery management method may include a step of updating the kth reference current of the charging map based on the current history of the battery current over the charging period of the constant voltage charging. The step of updating the k-th reference current of the charging map may include determining an average current during the charging period based on the current history, and updating the k-th reference current based on the average current. The battery management method may further include determining a ratio between the k-th reference current and the updated k-th reference current, and updating each of the remaining reference currents excluding the k-th reference current based on the ratio.

Advantages of the Invention

[0022] According to at least one of the embodiments of the present invention, it is possible to update a multi-stage constant current charging map based on a battery voltage and a battery current monitored during charging using the multi-stage constant current charging map.

[0023] Also, according to at least one of the embodiments of the present invention, even if the charging stage ends while being performed only for a part of a plurality of SOC ranges, based on the update result for the current rate of a part of the SOC ranges, it is possible to update the current rate of each of the remaining SOC ranges among the plurality of SOC ranges.

[0024] The advantages of the present invention are not limited to the above-described advantages, and other advantages of the present invention not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0025] 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

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0027] 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.

[0028] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only 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.

[0029] Terms including ordinals 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.

[0030] Throughout the specification, when a certain part "includes" a certain component, this means that, unless otherwise stated, 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.

[0031] Furthermore, throughout the specification, when a part is "connected (joined)" to another part, this includes not only the case where it is "directly connected (joined)", but also the case where it is "indirectly connected (joined)" via other elements in between.

[0032] FIG. 1 is a diagram illustrating the configuration of an electric vehicle according to the present invention.

[0033] 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.

[0034] The battery pack 10 includes a battery B, a switch 20, and a battery management system 100.

[0035] The battery B includes at least one battery cell. Each battery cell is not particularly limited in type as long as it can be repeatedly charged and discharged, such as, for example, a lithium-ion cell. 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.

[0036] The switch 20 is connected in series with the battery B. The switch 20 is provided in the current path for charging and discharging the battery B. The switch 20 is controlled to be turned on and off in response to a switching signal from the battery management system 100. The 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).

[0037] The inverter 30 is provided to convert the direct current from the battery B into an alternating current in response to a command from the battery management system 100. The electric motor 40 can be, for example, a three-phase alternating current motor. The electric motor 40 is driven using the alternating current power from the inverter 30.

[0038] The battery management system 100 may be responsible for overall control related to the charging and discharging of the battery B.

[0039] The battery management system 100 includes a sensing unit 110, a memory unit 120, and a control unit 140. The battery management system 100 may further include at least one of an interface unit 130 and a switch driver 150.

[0040] The sensing unit 110 includes a voltage sensor 111 and a current sensor 112. The sensing unit 110 may further include a temperature sensor 113.

[0041] The voltage sensor 111 is connected in parallel to the battery B and is configured to detect the battery voltage applied across both ends of the battery B and generate a voltage signal indicating the detected battery voltage. The current sensor 112 is connected in series to the battery B through a current path. The current sensor 112 is configured to detect the battery current flowing through the battery B and generate a current signal indicating the detected battery current. The temperature sensor 113 is configured to detect the temperature of the battery B and generate a temperature signal indicating the detected temperature.

[0042] The memory unit 120 can 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 can store data and programs required for the arithmetic operation by the control unit 140. The memory unit 120 can store data indicating the result of the arithmetic operation by the control unit 140.

[0043] 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, a battery manufacturer) or the upper controller 2 via the interface unit 130.

[0044] 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 between the first to nth reference SOC ranges, the first to nth reference currents, and the first to nth reference voltages for the multi - stage constant - current charging are recorded. n is a natural number of 2 or more. The subsequent reference current may be smaller than the previous reference current.

[0045] The interface unit 130 may include a communication circuit configured to assist in wired or wireless communication between the control unit 140 and the host controller 2 (for example, ECU: Electronic Control Unit). The wired communication may be, 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 wired or wireless communication between the control unit 140 and the host 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 host controller 2 in a form recognizable by the user. The host 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.

[0046] The control unit 140 may be operably coupled to the host 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 both directions.

[0047] 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.

[0048] The control unit 140 may collect sensing signals from the sensing unit 110. The sensing signals refer to synchronously detected voltage signals, current signals and / or temperature signals.

[0049] The control unit 140 can be implemented in hardware using at least one of an ASIC (application specific integrated circuit), a DSP (digital signal processor), a DSPD (digital signal processing device), a PLD (programmable logic device), an FPGA (field programmable gate array), a microprocessor, and other electrical units for performing functions.

[0050] 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 host 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 can 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 can end the charging stage using the charging map in response to receiving a charging interruption command via the interface unit 130.

[0051] The control unit 140 can determine the SOC of the battery B based on a sensing signal. Known algorithms such as an OCV (open circuit voltage)-SOC curve, ampere counting, and a Kalman filter can be used in determining the SOC.

[0052] FIG. 2 is a diagram illustrating the correspondence between the reference SOC range and the reference current recorded in the charging map, and FIG. 3 is a diagram illustrating the correspondence between the reference SOC range and the reference voltage recorded in the charging map. For convenience of explanation, in FIGS. 2 and 3, it is shown that n = 4, that is, the charging map defines the correspondence between four reference SOC ranges, four reference currents, and four reference voltages.

[0053] The first current profile 210 shown in FIG. 2 shows the correspondence between the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 and the first to fourth reference currents I1 to I4 for the battery B in a new state. The first current profile 210 can be recorded in the charging map in a format such as a data table. When k is a natural number less than or equal to n, S k is the upper limit value of the k-th reference SOC range ΔSOC k . When m is a natural number less than n, S m is the same as the lower limit value of the (m + 1)-th reference SOC range ΔSOC m+1 . For example, S1 is the lower limit value of the second reference SOC range ΔSOC2 having S2 as the upper limit value. The lower limit value S0 of the first reference SOC range ΔSOC1 can be 0%.

[0054] When the SOC of the battery B is within the m-th reference SOC range ΔSOC m , the control unit 140 may command the charging circuit 50 to perform constant current charging using the m-th reference current I m .

[0055] During the constant current charging using the m-th reference current I m , when the SOC of the battery B reaches the upper limit value S m of the m-th reference SOC range ΔSOC m , the control unit 140 may command the charging circuit 50 to perform constant current charging using the (m + 1)-th reference current I m+1 .

[0056] During the constant current charging using the n-th reference current I n , when the SOC of the battery B reaches the upper limit value S n of the n-th reference SOC range ΔSOC nWhen reaching this point, the constant-voltage charging can be commanded to the charging circuit 50. As a result, the multi-stage constant-current charging using the charging map is completed, and the charging can be switched to the constant-voltage charging.

[0057] The first voltage profile 310 shown in FIG. 3 shows the correspondence between the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 and the first to fourth reference voltages V1 to V4 for the battery B in the new state. The first voltage profile 310 can be recorded in the charging map in a format such as a data table. V k is the reference voltage determined in advance as the battery voltage when the SOC of the battery B in the new state reaches the upper limit value S k of the k-th reference SOC range ΔSOC k by the k-th reference current I k .

[0058] On the other hand, as described above, as the battery B gradually deteriorates, the voltage rise due to the same charging current becomes faster compared to the new state. As a result, during the constant-current charging using the k-th reference current I k of the charging map, 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 change in the battery voltage monitored through the process of charging the deteriorated battery B with the first to fourth reference currents I1 to I4 sequentially for the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4. Referring to the second voltage profile 320, V 1k is the battery voltage when the SOC of the deteriorated battery B reaches the upper limit value S k of the k-th reference SOC range ΔSOC k , and it can be confirmed that it is greater than the k-th reference voltage V k . That is, V 11 > V1, V 12 > V2, V 13 > V3, V 14 > V4.

[0059] The k-th reference voltage V kis the maximum voltage at which constant current charging using the k-th reference current I k is allowed. Therefore, within the k-th reference SOC range ΔSOC k if the battery voltage exceeds the k-th reference voltage V k the degradation of the battery B can be accelerated. Thus, during constant current charging using the k-th reference current I k when the battery voltage reaches the k-th reference voltage V k it is necessary to adjust the magnitude of the charging current to be smaller than the k-th reference current I k to suppress the degradation of the battery B.

[0060] The second current profile 220 shown in FIG. 2 and the third voltage profile 330 shown in FIG. 3 show the time series of the battery current and the battery voltage, i.e., the history of the change over time during charging, monitored through the process of charging the degraded battery B by applying the battery management method according to the present invention.

[0061] Referring to the third voltage profile 330, the control unit 140 monitors the battery voltage, the battery current, and the battery SOC every set time (for example, 0.001 seconds) during constant current charging using the k-th reference current I k . When the SOC of the battery B reaches the upper limit value S k of the k-th reference SOC range ΔSOC k before the battery voltage reaches the k-th reference voltage V k in response to this, 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, until the SOC of the battery B reaches the upper limit value S k of the k-th reference SOC range ΔSOC k after the battery voltage reaches the k-th reference voltage V k the battery B is charged at a constant voltage of the k-th reference voltage V k . Referring to the second current profile 220, the k-th reference voltage V kDuring constant voltage charging using [it], the battery current gradually decreases as the battery voltage gradually increases.

[0062] For example, constant current charging using the second reference current I2 is performed over the SOC range of S1 to Z2%, and then, over the SOC range of Z2 to S2% (second constant voltage charging range), the battery voltage of the battery B is charged at a constant voltage while being maintained the same as the second reference voltage V2. Also, during the constant voltage charging of the battery B by the second reference voltage V2, it can be confirmed from the second current profile 220 that the battery current gradually decreases from the second reference current I2.

[0063] The control unit 140 can update a charging map including the first current profile 210 in FIG. 2 and the first voltage profile 310 in FIG. 3 based on the battery voltage and the battery current monitored while the charging stages for at least one of the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 are sequentially performed.

[0064] Specifically, the control unit 140 can determine the k-th average current from the time series of the battery current (which can be referred to as the "current history") monitored over the k-th constant voltage charging period which is the charging period of the k-th constant voltage charging range Z k ~S k . The k-th average current can be the average of the battery currents repeatedly sensed every set time during the k-th constant voltage charging period. Therefore, the k-th average current is smaller than the k-th reference current I k .

[0065] Subsequently, the control unit 140 can update the k-th reference current I k of the charging map based on the k-th average current. The currents I 11 to I 14 in the third current profile 230 in FIG. 2 can each be the result of updating the reference currents I1 to I4 of the charging map.

[0066] The control unit 140 is the k-th reference current I kcan be updated to be the same as the k-th average current. For example, referring to FIG. 2, when the second reference current I2 = 120 A and the second average current = 100 A, the second reference current I2 of 120 A is smaller than 100 A of I 12 is changed to.

[0067] Alternatively, the control unit 140 may set the k-th reference current I k to be the same as the sum of the product of the k-th reference current and the first weighting value and the product of the k-th average current and the second weighting value. The first weighting value and the second weighting value are each positive numbers less than 1, and the sum of the first weighting value and the second weighting value may be 1. For example, when the second reference current I2 = 120 A, the second average current = 100 A, the first weighting value = 0.4, and the second weighting value = 0.6, the second reference current I2 of 120 A is changed to a smaller 108 A of I k and can be recorded in the charging map. 12 On the other hand, in the charging stage according to the battery management method described above, it is frequent that the charging is terminated without being sequentially performed for each of all the reference SOC ranges ΔSOC1 to ΔSOC4. For example, charging may be started before the battery B is completely discharged, or the vehicle user may separate the charging cable from the electric vehicle 1 before switching from constant current charging to constant voltage charging. In such a case, while it is possible to update the reference current corresponding to some of the reference SOC ranges for which the charging stage has been performed as described above, the reference current corresponding to the remaining reference SOC ranges may not be updated.

[0068] To solve the above problems, when charging is started when the SOC of the battery B is greater than S0, or when charging is terminated when the SOC of the battery B is less than S4, the control unit 140 may update the reference current related to each of the remaining reference SOC ranges based on the update information for at least one of the reference SOC ranges ΔSOC1 to ΔSOC4 among all the reference SOC ranges.

[0069] The k-th reference current I corresponding to the k-th reference SOC range ΔSOC

[0070] k k corresponding to kk Assume that only is updated to I by the battery management method described above. The control unit 140 can update each of the remaining reference currents based on the determined ratio after determining the ratio of to I. For example, when the second reference current I2 is updated from 120 A to 100 A, the control unit 140 can multiply the first reference current I1, the third reference current I3, and the fourth reference current I4 by 100 / 120 = 5 / 6 respectively to update the first reference current I1, the third reference current I3, and the fourth reference current I4. 1k Assume that it is updated to I. The control unit 140 can update each of the remaining reference currents based on the determined ratio after determining the ratio of to I. For example, when the second reference current I2 is updated from 120 A to 100 A, the control unit 140 can multiply the first reference current I1, the third reference current I3, and the fourth reference current I4 by 100 / 120 = 5 / 6 respectively to update the first reference current I1, the third reference current I3, and the fourth reference current I4. k For I with respect to I 1k Assume that only is updated to I by the battery management method described above. The control unit 140 can update each of the remaining reference currents based on the determined ratio after determining the ratio of to I. For example, when the second reference current I2 is updated from 120 A to 100 A, the control unit 140 can multiply the first reference current I1, the third reference current I3, and the fourth reference current I4 by 100 / 120 = 5 / 6 respectively to update the first reference current I1, the third reference current I3, and the fourth reference current I4.

[0071] Assume that i and j are each natural numbers, i ≤ j, i is 2 or more, and j is less than n. The i-th to j-th reference SOC ranges ΔSOC i ~ΔSOC j The i-th to j-th reference currents I corresponding to i ~I j Only are updated from I to I by the battery management method (see FIG. 4). i ~I j from I 1i ~I 1j The charging stage can end while remaining updated to ~ respectively. Then, the control unit 140 can update each of the remaining reference currents using the following formula.

Equation

[0072] 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 1x is the updated reference current. μ avg is the average ratio 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 after update.

[0073] In one example, i = 2, j = 3, n = 4, i1 = 150 A, i2 = 120 A, i 12= 100 A, i3 = 110 A, i 13 = 95 A, i4 = 90 A, when i 11 = i1 × 1 / 2 × {100 / 120 + 95 / 110} A ≒ 127 A, and i 14 = i4 × 1 / 2 × {100 / 120 + 95 / 110} A ≒ 76 A.

[0074] Figure 4 is a flowchart illustrating the battery management method according to the first embodiment of the present invention.

[0075] Referring to FIGS. 1 to 4, in step S410, in response to a charge start command, the control unit 140 reads from the memory unit 120 the charge maps 210 and 310 in which the correspondence relationships with the first to nth reference SOC ranges ΔSOC1 to ΔSOC n and the first to nth reference currents I1 to I n and the first to nth reference voltages V1 to V n are recorded.

[0076] In step S420, the control unit 140 selects the kth reference SOC range ΔSOC n to which the SOC of the battery B belongs among the first to nth reference SOC ranges ΔSOC1 to ΔSOC k For example, when the SOC of the battery B is equal to or greater than S1 and less than S2, the second reference SOC range ΔSOC2 is selected.

[0077] In step S430, the control unit 140 starts constant current charging using the kth reference current I k corresponding to the kth reference SOC range ΔSOC k

[0078] In step S440, the control unit 140 determines whether the battery voltage has reached the kth reference voltage V k corresponding to the kth reference SOC range ΔSOC k before the SOC of the battery reaches the upper limit value S k of the kth reference SOC range ΔSOC k If the value in step S440 is "yes", the process proceeds to step S450.

[0079] In step S450, the control unit 140 switches from constant current charging using the k-th reference current I k to constant voltage charging using the k-th reference voltage V k .

[0080] In step S460, the control unit 140 determines whether the SOC of the battery has reached the upper limit value S k of the k-th reference SOC range ΔSOC k . If the value in step S460 is "Yes", proceed to step S470.

[0081] In step S470, the control unit 140 updates the k-th reference current I k of the charging map based on the current history of the battery current over the charging period of the constant voltage charging using the k-th reference voltage V k .

[0082] In step S480, the control unit 140 determines whether the k-th reference SOC range ΔSOC k is the n-th reference SOC range ΔSOC n . That is, the control unit 140 determines whether the SOC of the battery B has reached the maximum SOC S n specified by the charging map for multi-stage constant current charging. If the value in step S480 is "No", return to step S420. If the value in step S480 is "Yes", the method in FIG. 4 ends.

[0083] For reference, when a charging start command is received in a state where the update condition is not satisfied, steps S440 to S470 in the method of FIG. 4 can be omitted.

[0084] 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 without necessity. For example, it can be indicated that the degradation degree of the battery B has increased to a certain level or more, such as the accumulated capacity of the battery B has increased by a first critical value (for example, 100 Ah [ampere - hour]) or more compared to the accumulated capacity at the time of the previous update, the number of cycles of the battery B has increased by a second critical value (for example, 50 times) or more compared to the number of cycles at the time of the previous update, the capacity retention rate of the battery B has decreased by a third critical value (for example, 5%) or more compared to the capacity retention rate at the time of the previous update, a result of a critical time (for example, one month) or more has elapsed since the previous update, and so on.

[0085] 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 (for example, Z1 to S3 in FIG. 2) of the entire SOC range of S0 to S n by the fourth method. As described above, i and j are each natural numbers, i < j, i is 2 or more, or j is less than n.

[0086] 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 with respect to the i - th to j - th reference currents I 1i ~I 1j (refer to μ avg in the above formula).

[0087] 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 each reference current excluding the i-th to j-th reference currents I i ~I j to update each reference current.

[0088] The embodiments of the present invention described above are not necessarily implemented through the device and method, but can 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 belongs from the description of the above-described embodiments.

[0089] 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 belongs.

[0090] Also, 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 belongs. 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 voltage sensor for measuring the battery voltage; a current sensor for measuring the battery current; a memory unit for storing a charging map in which a correspondence relationship between first to n-th reference SOC ranges and first to n-th reference currents for multi-stage constant current charging is recorded; a control unit that, in response to a charge start command, starts constant current charging using a k-th reference current corresponding to a k-th reference SOC range to which the SOC of the battery belongs among the first to n-th reference SOC ranges, switches from the constant current charging to constant voltage charging using the k-th reference voltage in response to the battery voltage reaching the k-th reference voltage corresponding to the k-th reference SOC range before the SOC of the battery reaches an upper limit value of the k-th reference SOC range during the constant current charging, and starts constant current charging using the (k+1)-th reference current corresponding to the (k+1)-th reference SOC range among the first to n-th reference SOC ranges when the SOC of the battery reaches the upper limit value of the k-th reference SOC range during the constant voltage charging, The kth reference voltage is a voltage when an SOC of the battery reaches an upper limit value of the kth reference SOC range in voltage data corresponding to the kth reference SOC range.

2. The kth reference voltage is The battery management system of claim 1 , wherein the (k+1)th reference SOC range is greater than a starting voltage of the (k+1)th reference SOC range.

3. The control unit is after starting constant current charging using the (k+1)th reference current corresponding to the (k+1)th reference SOC range, in response to a battery voltage reaching the (k+1)th reference voltage corresponding to the (k+1)th reference SOC range before the SOC of the battery reaches an upper limit value of the (k+1)th reference SOC range, switching from the constant current charging to constant voltage charging using the (k+1)th reference voltage; 2. The battery management system according to claim 1, wherein the (k+1)th reference voltage is a voltage when the SOC of the battery reaches an upper limit value of the (k+1)th reference SOC range in voltage data corresponding to the (k+1)th reference SOC range.

4. The control unit is The battery management system of claim 1 , further comprising: updating the kth reference current of the charging map based on a current history of the battery current over a charging period of the constant voltage charging.

5. The control unit is determining an average current during the charging period based on the current history; The battery management system of claim 4 , further comprising updating the kth reference current based on the average current.

6. The control unit is determining an average current during the charging period based on the current history; The battery management system of claim 4 , further comprising: updating the kth reference current based on a sum of a product of the kth reference current and a first weighted value and a product of the average current and a second weighted value.

7. The battery management system of claim 6 , wherein the first weight value and the second weight value are each a positive number less than 1, and a sum of the first weight value and the second weight value is 1.

8. The control unit is The battery management system of claim 4 , further comprising: updating each remaining reference current, except for the kth reference current, based on a ratio of the updated kth reference current to the kth reference current.

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

10. An electric vehicle comprising the battery pack of claim 9.

11. 1. A battery management method, comprising: reading out a charging map in which a correspondence relationship between first to n-th reference SOC ranges and first to n-th reference currents for multi-stage constant current charging is recorded in response to a charging start command; starting constant current charging using a k-th reference current corresponding to a k-th reference SOC range to which the SOC of the battery belongs among the first to n-th reference SOC ranges; during the constant current charging, in response to a battery voltage reaching a k-th reference voltage corresponding to the k-th reference SOC range before the SOC of the battery reaches an upper limit value of the k-th reference SOC range, switching from the constant current charging to constant voltage charging using the k-th reference voltage; and when the SOC of the battery reaches an upper limit value of the kth reference SOC range during the constant voltage charging, starting constant current charging using a (k+1)th reference current corresponding to a (k+1)th reference SOC range among the first to nth reference SOC ranges; The battery management method, wherein the kth reference voltage is a voltage when the SOC of the battery reaches an upper limit value of the kth reference SOC range in voltage data corresponding to the kth reference SOC range.

12. The kth reference voltage is The battery management method of claim 11 , wherein the (k+1)th reference SOC range is higher than a starting voltage of the (k+1)th reference SOC range.

13. the method further includes a step of switching from the constant current charging to constant voltage charging using the (k+1)th reference voltage in response to a battery voltage reaching the (k+1)th reference voltage corresponding to the (k+1)th reference SOC range before the SOC of the battery reaches an upper limit value of the (k+1)th reference SOC range after starting the constant current charging using the (k+1)th reference current corresponding to the (k+1)th reference SOC range, 13. The battery management method of claim 12, wherein the (k+1)th reference voltage is a voltage when the SOC of the battery reaches an upper limit value of the (k+1)th reference SOC range in voltage data corresponding to the (k+1)th reference SOC range.

14. 13. The battery management method of claim 12, further comprising updating the kth reference current of the charging map based on a current history of the battery over a charging period of the constant voltage charging.

15. updating the kth reference current of the charging map, determining an average current during the charging period based on the current history; and updating the kth reference current based on the average current.

16. determining a ratio between the kth reference current and the updated kth reference current; 15. The battery management method of claim 14, further comprising: updating each remaining reference current except for the kth reference current based on the ratio.

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