Battery management systems, battery management methods, battery packs, and electric vehicles

Abstract

We provide a battery management system that updates the multi-stage constant current charging map. [Solution] The battery management system 100 includes a memory unit 120 that stores a charging map recording the correspondence between the first to nth reference SOC ranges and the first to nth reference currents for multi-stage constant current charging, and a control unit 140 that starts constant current charging using the kth reference current corresponding to the kth reference SOC range to which the battery's SOC belongs among the first to nth reference SOC ranges, switches from constant current charging to constant voltage charging using the kth reference voltage when the battery voltage reaches the kth reference voltage corresponding to the kth reference SOC range before the SOC of battery B reaches the upper limit of the kth reference SOC range, 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 nth reference SOC ranges when the SOC of battery B reaches the upper limit of the kth reference SOC range during constant voltage charging.

Description

[Technical Field]

[0001] This invention relates to a technology for controlling battery charging.

[0002] This application claims priority based on Korean Patent Application No. 10-2020-0101934, filed on 13 August 2020, and all content disclosed in the specification and drawings of the said application is incorporated into this application. [Background technology]

[0003] Recently, with the surge in demand for portable electronic products such as notebook PCs, video cameras, and mobile phones, and with the full-scale development of electric vehicles, energy storage batteries, robots, and satellites, research into high-performance batteries capable of repeated charging and discharging is progressing rapidly.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention because they exhibit almost no memory effect compared to nickel-based batteries, allow for flexible charging and discharging, have a very low self-discharge rate, and have a high energy density.

[0005] When charging a battery with a constant current, a low charging current rate requires a very long time to fully charge the battery. On the other hand, if the charging current rate is too high, there is a side effect of the battery degrading quickly.

[0006] One of the charging protocols proposed to solve the above problems is "multi-stage constant-current charging," which adjusts the current rate of the charging current in stages according to the charge state and voltage of the battery during charging. The current rate is the value obtained by dividing the charging current by the maximum capacity of the battery, and is sometimes called "C-rate," with "C" as the unit. A multi-stage constant-current charging map includes at least one data array that records the correspondence between multiple current rates and multiple SOC (State of Charge) ranges. The charging stages using a multi-stage constant-current charging map are carried out by repeating the process of supplying a charging current of the next order of current rates to the battery each time the battery's SOC reaches the upper limit of each SOC range.

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

[0008] However, conventional charging methods using multi-stage constant-current charging maps have the problem of not taking battery degradation into account. [Prior art document] [Patent] Patent Document 1: Specification of U.S. Patent Application Publication No. 2015 / 0340885 Patent Document 2, International Publication No. 2011 / 061902 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention has been made in view of the above-mentioned problems, and aims 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 the battery voltage and battery current monitored during charging using a multi-stage constant current charging map.

[0010] Furthermore, the present invention also aims to provide a battery management system, a battery management method, a battery pack, and an electric vehicle that update the current rates of the remaining SOC ranges based on the update results for the current rates of some SOC ranges, even if the charging stage is terminated after being performed on only some of the SOC ranges.

[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. Furthermore, the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0012] A battery management system according to one aspect of the present invention includes: a voltage sensor for measuring battery voltage; a current sensor for measuring battery current; a memory unit for storing a charging map in which the correspondence between the first to nth reference SOC ranges and the first to nth reference currents for multi-stage constant current charging is recorded; and a control unit that, in response to a charging start command, starts constant current charging using the kth reference current corresponding to the kth reference SOC range to which the battery's SOC belongs among the first to nth reference SOC ranges; switches from constant current charging to constant voltage charging using the kth reference voltage when the battery voltage reaches the kth reference voltage corresponding to the kth reference SOC range before the battery's SOC reaches the upper limit of the kth reference SOC range; 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 nth reference SOC ranges. The k reference voltage is the voltage at which the State of Charge (SOC) of the battery reaches the upper limit of the k reference SOC range.

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

[0014] The control unit may switch from constant current charging to constant voltage charging using the (k+1) reference voltage after starting constant current charging using the (k+1) reference current corresponding to the (k+1) reference SOC range, in response to the battery voltage reaching the (k+1) reference voltage corresponding to the (k+1) reference SOC range before the SOC of the battery reaches the upper limit of the (k+1) reference SOC range. The (k+1) reference voltage may be the voltage at which the SOC of the battery reaches the upper limit of the (k+1) reference SOC range.

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

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

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

[0018] The control unit may be configured to update each of the remaining reference currents, excluding the k reference current, based on the ratio of the updated k reference current to the k reference current.

[0019] Furthermore, a battery pack according to another aspect of the present invention includes the battery management system.

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

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

[0022] According to at least one embodiment of the present invention, the multi-stage constant current charging map can be updated based on the battery voltage and battery current monitored during charging using the multi-stage constant current charging map.

[0023] Furthermore, according to at least one embodiment of the present invention, even if the charging phase is completed while only a portion of the multiple SOC ranges have been charged, the current rates of the remaining SOC ranges can be updated based on the update results for the current rates of the portion of the SOC ranges.

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

[0025] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, serve to further illustrate the technical idea of ​​the invention. Therefore, the invention should not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0026] [Figure 1] This diagram illustrates the configuration of an electric vehicle according to the present invention. [Figure 2] This diagram illustrates the correspondence between the reference SOC range and the reference current recorded in the charging map. [Figure 3] This diagram illustrates the correspondence between the reference SOC range and the reference voltage recorded in the charging map. [Figure 4]This is a flowchart illustrating a battery management method according to the first embodiment of the present invention. [Figure 5] This is a flowchart illustrating a battery management method according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0027] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their usual or dictionary meanings, but rather in a manner corresponding to the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0028] Therefore, it should be understood that the embodiments and configurations shown in the drawings described herein represent only one of the most preferred embodiments of the present invention and do not represent the entirety of the technical concept of the present invention, and that there are various equivalents and modifications that can be substituted for them at the time of this application.

[0029] Terms that include ordinal numbers, such as "first," "second," etc., are used to distinguish one of several components from the rest, and do not mean that such terms limit the components.

[0030] Furthermore, throughout the specification, when a part of it "includes" a certain component, unless otherwise stated, this does not mean that other components are excluded, but rather that other components may be included. Also, terms such as "control unit" in the specification refer to a unit that processes at least one function or operation, which can be embodied by hardware, software, or a combination of hardware and software.

[0031] Furthermore, when a part of the specification is described as being "connected" to another part, this includes not only cases where it is "directly connected," but also cases where it is "indirectly connected" through other elements in between.

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

[0033] Referring to Figure 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 battery B, switch 20, and battery management system 100.

[0035] Battery B includes at least one battery cell. The type of each battery cell is not particularly limited, as long as it is capable of repeated charging and discharging, such as a lithium-ion cell. Battery B can be coupled to the inverter 30 and / or charging circuit 50 through a pair of power terminals provided on the battery pack 10.

[0036] Switch 20 is connected in series with battery B. Switch 20 is located in the current path for charging and discharging battery B. Switch 20 is controlled on and off in response to a switching signal from the battery management system 100. Switch 20 may be a mechanical relay that is switched 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 DC current from battery B to AC current in response to a command from the battery management system 100. The electric motor 40 may be, for example, a three-phase AC motor. The electric motor 40 is driven using the AC power from the inverter 30.

[0038] The battery management system 100 may be responsible for overall control related to the charging and discharging of 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 battery B and is configured to detect the battery voltage across battery B and generate a voltage signal indicating the detected battery voltage. The current sensor 112 is connected in series to battery B through a current path. The current sensor 112 is configured to detect the battery current flowing through battery B and generate a current signal indicating the detected battery current. The temperature sensor 113 is configured to detect the temperature of battery B and generate a temperature signal indicating the detected temperature.

[0042] The memory unit 120 may include at least one type of storage medium, such as flash memory 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), or PROM (programmable read-only memory). The memory unit 120 may store data and programs required for calculation operations by the control unit 140. The memory unit 120 may store data indicating the results of calculation operations by the control unit 140.

[0043] The memory unit 120 stores the charging map. The charging map may have been pre-stored in the memory unit 120 before the battery management system 100 was shipped, or it may have been received via the interface unit 130 from an external source (e.g., a battery manufacturer) or a higher-level controller 2.

[0044] The charge map is used for the charging stages of multi-stage constant-current charging of battery B. The charge map records the correspondence between the 1st to nth reference SOC ranges, the 1st to nth reference currents, and the 1st to nth reference voltages for multi-stage constant-current charging. n is a natural number greater than or equal to 2. The reference current of a later priority may be smaller than the reference current of a earlier priority.

[0045] The interface unit 130 may include a communication circuit configured to support wired or wireless communication between the control unit 140 and the higher-level controller 2 (e.g., ECU: Electronic Control Unit). Wired communication may be, for example, CAN (controller area network) communication, and wireless communication may be, for example, Zigbee® or Bluetooth® communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired or wireless communication between the control unit 140 and the higher-level controller 2. The interface unit 130 may include an output device (e.g., display, speaker) that provides information received from the control unit 140 and / or the higher-level controller 2 in a form that is recognizable to the user. The higher-level controller 2 may control the inverter 30 based on battery information (e.g., voltage, current, temperature, SOC) collected through communication with the battery management system 100.

[0046] The control unit 140 can be operably coupled to the higher-level 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 operable coupling of the two components means that they are directly or indirectly connected in a way that allows them to send and receive signals unidirectionally or bidirectionally.

[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 the switch 20 on and off in response to commands from the control unit 140. The control unit 140 may command the switch driver 150 to turn on the switch 20 during the charging phase.

[0048] The control unit 140 can collect sensing signals from the sensing unit 110. 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 the following: 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, or other electrical units for performing functions.

[0050] The interface unit 130 can relay bidirectional communication between the control unit 140 and the charging circuit 50, and bidirectional communication between the control unit 140 and the higher-level controller 2. The charging circuit 50 is configured to supply a charging current to the battery B at a current rate requested by the battery management system 100. The charging circuit 50 may be configured to supply a charging voltage to the battery B having a voltage level requested by the battery management system 100. The control unit 140 is configured to start a charging phase using a charging map in response to receiving a charging start command via the interface unit 130. The control unit 140 may terminate a charging phase using a charging map in response to receiving a charging interruption command via the interface unit 130.

[0051] The control unit 140 can determine the State of Charge (SOC) of battery B based on the sensing signal. Known algorithms such as the OCV (open circuit voltage)-SOC curve, ampere counting, and Kalman filter can be used to determine 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 the 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 instruct 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 instruct 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 this condition is reached, the charging circuit 50 can be instructed to perform constant voltage charging. This can terminate multi-stage constant current charging using the charging map and switch to constant voltage charging.

[0057] The first voltage profile 310 shown in Figure 3 illustrates the correspondence between the first to fourth reference SOC ranges ΔSOC1 to ΔSOC4 and the first to fourth reference voltages V1 to V4 for a new battery B. The first voltage profile 310 can be recorded in the charge map in a format such as a data table. k The State of Charge (SOC) of battery B, which is in new condition, is the k-th reference current I k The k-th criterion SOC range ΔSOC k Upper limit S k This is a predetermined reference voltage that indicates the battery voltage when it reaches a certain point.

[0058] On the other hand, as mentioned above, as battery B gradually degrades, the voltage rise with the same amount of charging current becomes faster compared to when it was new. This affects the k-th reference current I in the charging map. k During constant current charging using the k-th reference voltage V k Reaching this point indicates that battery B has degraded compared to its new state. The second voltage profile 320 shown in Figure 3 shows the change in battery voltage monitored during the process of constant current charging of the degraded battery B using 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 The state of affairs (SOC) of the degenerated battery B is within the k-th reference SOC range ΔSOC. k Upper limit S k The battery voltage when it reaches the k-th reference voltage V k We can confirm that it is greater than V. 11 >V1, V 12 >V2, V 13 >V3, V 14 It is V4.

[0059] The kth reference voltage V kis the k-th reference current I k Since constant current charging using this method is the maximum voltage that is permissible, the k-th reference SOC range ΔSOC k The battery voltage inside is the kth reference voltage V k Exceeding this value can accelerate the degeneration of battery B. Therefore, the k-th reference current I k During constant current charging using the k-th reference voltage V k If this is reached, the magnitude of the charging current will be set to the k-th reference current I in order to suppress the degeneration of battery B. k It needs to be adjusted to be smaller.

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

[0061] Referring to the third voltage profile 330, the control unit 140 controls the k-th reference current I k During constant current charging using the system, the battery voltage, battery current, and battery SOC are monitored at set time intervals (e.g., 0.001 seconds). The control unit 140 determines that the SOC of battery B is within the k-th reference SOC range ΔSOC. k Upper limit S k Before reaching the kth reference voltage V k In accordance with reaching the k-th reference current I k Constant current charging using the k-th reference voltage V k It can be switched to constant voltage charging using this method. This allows the battery voltage to be the kth reference voltage V k When it reaches the k-th reference SOC range ΔSOC, the SOC of battery B is k Upper limit S k Until it reaches the kth reference voltage V, battery B k It is charged at a constant voltage. Referring to the second current profile 220, the k reference voltage V kDuring constant voltage charging using this method, the battery voltage gradually increases, causing the battery current to gradually decrease.

[0062] For example, constant current charging is performed using the second reference current I2 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 battery B is maintained at the same level as the second reference voltage V2 while constant voltage charging is performed. Furthermore, it can be confirmed from the second current profile 220 that the battery current gradually decreases from the second reference current I2 during constant voltage charging of battery B using the second reference voltage V2.

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

[0064] Specifically, the control unit 140 controls the k-th constant voltage charging range Z k ~S k The k-th average current can be determined from the time series of battery currents monitored over the k-th constant voltage charging period (which may be called the "current history"). The k-th average current can be the average of the battery currents sensed iteratively at set time intervals during the k-th constant voltage charging period. Therefore, the k-th average current is equal to the k-th reference current I k Smaller.

[0065] Next, the control unit 140 sets the k-th reference current I of the charge map based on the k-th average current. k This can be updated. The current I of the third current profile 230 in Figure 2 11 ~I 14 These could be the result of updating the reference currents I1 to I4 in the charging map.

[0066] The control unit 140 controls the k-th reference current I kThis can be updated to be the same as the k-th mean current. For example, referring to Figure 2, if the second reference current I2 = 120A and the second mean current = 100A, then the second reference current I2 of 120A is smaller than the I of 100A. 12 It will be changed to this.

[0067] Alternatively, the control unit 140 controls the k-th reference current I k The sum of the product of the first weighting value and the product of the k-average current and the second weighting value is the same as the k-reference current I k The first and second weights are positive numbers less than 1, and the sum of the first and second weights can be 1. For example, if the second reference current I2 = 120A, the second average current = 100A, the first weight = 0.4, and the second weight = 0.6, then the second reference current I2 of 120A is less than 108A. 12 This can be changed and recorded in the charging map.

[0068] On the other hand, the charging stages according to the aforementioned battery management method are frequently terminated without being performed sequentially for each of the reference SOC ranges ΔSOC1 to ΔSOC4. For example, charging may start before battery B is completely discharged, or the vehicle user may disconnect the charging cable from electric vehicle 1 before the switch from constant current charging to constant voltage charging is completed. In such cases, while it may be possible to update the reference current corresponding to some of the reference SOC ranges for which the charging stage was performed as described above, the reference current corresponding to the remaining reference SOC ranges may not be updated.

[0069] To solve the aforementioned problems, the control unit 140 may update the reference currents related to each of the remaining reference SOC ranges based on update information for at least one of the reference SOC ranges ΔSOC1 to ΔSOC4, when charging of battery B starts when the SOC of battery B is greater than S0, or when charging ends when the SOC of battery B is less than S4.

[0070] k-th criterion SOC range ΔSOC k Corresponding k-th reference current Ik Only by the aforementioned battery management method I 1k Let's assume it has been updated to I. The control unit 140 is I k I 1k After determining the ratio, the remaining reference currents can be updated based on the determined ratio. For example, if the second reference current I2 is updated from 120A to 100A, the control unit 140 can update the first reference current I1, the third reference current I3, and the fourth reference current I4 by multiplying them by 100 / 120 = 5 / 6, respectively.

[0071] Assume that i and j are natural numbers, i ≤ j, i is greater than or equal to 2, and j is less than n. The i-th to j-th criterion SOC range ΔSOC i ~ΔSOC j The i- to j-th reference currents I corresponding to i ~I j Only by the battery management method (see Figure 4) i ~I j From I 1i ~I 1j The charging phase may end with each of the currents still updated. In that case, the control unit 140 can update each of the remaining reference currents using the following formula.

number

[0072] In the above formula, x is a natural number less than or equal to n, excluding i to j, and I x This is the reference current before the update, and I 1x This is the updated reference current. μ avg This is the i-th to j-th reference current I i ~I j Updated reference currents I for the i-jth order 1i ~I 1j This is the average proportion.

[0073] For example, i=2, j=3, n=4, i1=150A, i2=120A, 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, 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 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 charge maps 210 and 310 from being updated unnecessarily frequently. For example, it is shown that the degradation degree of the battery B has increased above a certain level. For example, 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, and the result is more than a critical time (e.g., one month) from the time of the previous update, etc.

[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 (e.g., Z1 to S3 in FIG. 2) of the entire SOC range from S0 to S n as described above. 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 nOf these, the i- to j-th reference current I i ~I j Each of the remaining reference currents is multiplied by the average ratio, and each reference current is updated.

[0088] The embodiments of the present invention described above are not necessarily embodied through apparatus and methods, but can also be embodied through a program that realizes the functions corresponding to the configuration of the embodiments of the present invention, or through a recording medium on which such a program is recorded. Such embodiment should be easily realized by experts in the art to which the present invention belongs, based on the descriptions of the embodiments above.

[0089] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains.

[0090] Furthermore, since the present invention described above can be substituted, modified, and altered in various ways by a person with ordinary skill in the art to which the present invention belongs, without deviating from the technical concept of the present invention, it is not limited by the above-described embodiments and the attached drawings, and can be constructed by selectively combining all or part of each embodiment to allow for various modifications.

Claims

1. A voltage sensor for measuring battery voltage, A current sensor for measuring battery current, A memory unit that stores a charging map in which the correspondence between the first to nth reference SOC ranges and the first to nth reference currents for multi-stage constant current charging is recorded, The system includes a control unit that, in response to a charging start command, starts constant current charging using the k-th reference current corresponding to the k-th reference SOC range from the first to n-th reference SOC ranges to which the battery's SOC belongs, switches from constant current charging to constant voltage charging using the k-th reference voltage when the battery voltage reaches the k-th reference SOC range before the battery's SOC reaches the upper limit of the k-th reference SOC range, and starts constant current charging using the (k+1)-th reference current corresponding to the (k+1)-th reference SOC range from the first to n-th reference SOC ranges, A battery management system in which the k reference voltage is the voltage at which the SOC of the battery reaches the upper limit of the k reference SOC range.

2. The aforementioned k reference voltage is, The battery management system according to claim 1, wherein the starting voltage is higher than the (k+1) reference SOC range.

3. The control unit, After the start of constant current charging using the (k+1) reference current corresponding to the (k+1) reference SOC range, if the battery voltage reaches the (k+1) reference voltage corresponding to the (k+1) reference SOC range before the SOC of the battery reaches the upper limit of the (k+1) reference SOC range, the system switches from constant current charging to constant voltage charging using the (k+1) reference voltage. The battery management system according to claim 1, wherein the (k+1) reference voltage is the voltage at which the SOC of the battery reaches the upper limit of the (k+1) reference SOC range.

4. The control unit, The battery management system according to claim 1, which updates the k-th reference current of the charging map based on the current history of the battery current over the charging period of the constant voltage charging.

5. The control unit, Based on the current history, the average current during the charging period is determined. The battery management system according to claim 4, which updates the k reference current based on the average current.

6. The control unit, Based on the current history, the average current during the charging period is determined. The battery management system according to claim 4, which updates the k reference current based on the sum of the product of the k reference current and a first weighting value and the product of the average current and a second weighting value.

7. The battery management system according to claim 6, wherein 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 is 1.

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

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

10. An electric vehicle comprising the battery pack described in claim 9.

11. A battery management method, In response to a charge start command, the process involves reading a charge map in which the correspondence between the first to nth reference SOC ranges for multi-stage constant current charging and the first to nth reference currents is recorded. A step of starting constant current charging using the k-th reference current corresponding to the k-th reference SOC range to which the battery's SOC belongs among the first to n-th reference SOC ranges, During the constant current charging, if the battery voltage reaches the k-reference voltage corresponding to the k-reference SOC range before the battery's SOC reaches the upper limit of the k-reference SOC range, the charging method switches from constant current charging to constant voltage charging using the k-reference voltage. The step includes, when the State of Charge (SOC) of the battery reaches the upper limit of the k-reference SOC range during the constant voltage charging, starting constant current charging using the (k+1) reference current corresponding to the (k+1) reference SOC range among the first to n-reference SOC ranges, A battery management method in which the k reference voltage is the voltage at which the SOC of the battery reaches the upper limit of the k reference SOC range.

12. The aforementioned k reference voltage is, The battery management method according to claim 11, wherein the starting voltage is higher than the (k+1) reference SOC range.

13. The process further includes a step of switching from constant current charging to constant voltage charging using the (k+1) reference voltage, in response to the battery voltage reaching the (k+1) reference voltage corresponding to the (k+1) reference SOC range before the SOC of the battery reaches the upper limit of the (k+1) reference SOC range, The battery management method according to claim 12, wherein the (k+1) reference voltage is the voltage at which the SOC of the battery reaches the upper limit of the (k+1) reference SOC range.

14. The battery management method according to claim 12, further comprising the step of updating the k-th reference current of the charging map based on the current history of the battery over the charging period of the constant voltage charging.

15. The step of updating the k reference current of the charging map is: A step of determining the average current during the charging period based on the current history, The battery management method according to claim 14, comprising the step of updating the k reference current based on the average current.

16. A step of determining the ratio between the k reference current and the updated k reference current, The battery management method according to claim 14, further comprising the step of updating each of the remaining reference currents excluding the k reference current based on the aforementioned ratio.

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