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

Abstract

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

Description

[Technical Field]

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

[0002] This application claims priority based on Korean Patent Application No. 10-2020-0104883, filed on August 20, 2020, and all content disclosed in the specification and drawings of the said application is incorporated herein. [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 voltage ranges and multiple current rates. 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 voltage reaches the upper limit of each voltage range.

[0007] As a battery degrades from its initial state (BOL: Beginning of Life), the degradation at the same current rate can accelerate. For example, constant current charging using the same current rate across a specific voltage range can induce more lithium deposition as the battery degrades.

[0008] However, conventional charging methods using multi-stage constant-current charging maps have the problem of not taking into account the battery's operating state, which changes over time (for example, degeneration). [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 project] [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 the multi-stage constant current charging map according to the operating state of the battery based on the voltage and current of the battery monitored during charging using a multi-stage constant current charging map.

[0010] Another objective 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 for the remaining voltage ranges where constant current charging has not been performed, based on the update result for the current rate for at least one voltage range where constant current charging has been performed, even if the charging stage is terminated without being performed for the entire range of multiple voltages.

[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 sensing unit that generates a sensing signal indicating the battery voltage of a battery; a memory unit that stores a charging map recording the correspondence between first to nth reference currents for multi-stage constant current charging and first to nth reference voltage ranges; and a control unit that commands a charging circuit connected to the battery to perform constant current charging using the kth reference current corresponding to the kth reference voltage range to which the battery voltage belongs, and during the constant current charging, commands the charging circuit to perform constant voltage charging using the upper limit of the kth reference voltage range when the battery voltage reaches the upper limit of the kth reference voltage range, and when the State of Charge (SOC) of the battery reaches the upper limit of the kth reference SOC range due to the constant voltage charging, starts constant current charging using the k+1th reference current corresponding to the k+1th reference voltage range. The kth reference voltage is the voltage that is the upper limit of the kth reference voltage range.

[0013] The k reference voltage may be lower than the starting voltage of the k+1 reference voltage range. The control unit may, after starting constant current charging using the k+1 reference current corresponding to the k+1 reference voltage range, switch from constant current charging to constant voltage charging using the k+1 reference voltage when the battery voltage reaches the upper limit of the k+1 reference voltage range. The k+1 reference voltage may be the voltage at which the battery voltage reaches the upper limit of the k+1 reference voltage range.

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

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

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

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

[0018] The control unit may be configured to update the k reference current based on the ratio of the SOC of interest to the k reference SOC. The SOC of interest may be the SOC of the battery at the point in time when the battery voltage reaches the upper limit of the k reference voltage range.

[0019] 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.

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

[0021] A battery management method according to another aspect of the present invention includes the steps of: commanding a charging circuit connected to a battery to perform constant current charging using the kth reference current corresponding to the kth reference voltage range to which the battery voltage of the battery belongs, based on a charging map that records the correspondence between first to nth reference currents and first to nth reference voltage ranges for multi-stage constant current charging; and commanding the charging circuit to perform constant voltage charging using the upper limit of the kth reference voltage range when the battery voltage reaches the upper limit of the kth reference voltage range during the constant current charging, and starting constant current charging using the k+1 reference current corresponding to the k+1 reference voltage range when the state of charge (SOC) of the battery reaches the upper limit of the kth reference SOC range due to the constant voltage charging. The kth reference voltage is the voltage that is the upper limit of the kth reference voltage range.

[0022] The k reference voltage may be lower than the starting voltage of the k+1 reference voltage range. 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 voltage range, in response to the battery voltage reaching the upper limit of the k+1 reference voltage range. The k+1 reference voltage may be the voltage at which the battery voltage reaches the upper limit of the k+1 reference voltage range. The battery management method may further include the step of updating the charging map by comparing a k-th measured voltage curve, which shows the correspondence between the battery voltage and the battery's SOC over the charging period of the constant current charging using the k-th reference current, with the k-th reference voltage curve, in response to the battery voltage reaching the upper limit of the k-th reference voltage range. The step of updating the charging map may involve updating the k reference current based on the ratio of the average SOC of the k measured voltage curve to the average SOC of the k reference voltage curve. [Effects of the Invention]

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

[0024] Furthermore, according to at least one embodiment of the present invention, even if the charging stage is terminated without being performed over the entire range of voltages, the current rate for the remaining voltage ranges where constant current charging was not performed can be updated based on the update result for the current rate for at least one voltage range where constant current charging was performed.

[0025] 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.

[0026] 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]

[0027] [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 current and reference voltage range recorded in the charging map. [Figure 3] This diagram illustrates the correspondence between the reference voltage range recorded in the charging map and the reference SOC. [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]

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

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

[0034] 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.

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

[0036] 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.

[0037] 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).

[0038] 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 AC power from the inverter 30.

[0039] The battery management system 100 may be responsible for overall control related to the charging and discharging of battery B.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] The memory unit 120 stores the charging map. The charging map may be pre-stored in the memory unit 120 before the battery management system 100 is shipped, or it may be received from an external source (e.g., a battery manufacturer) or a higher-level controller 2 via the interface unit 130. The data recorded in the charging map may be predetermined based on test and / or simulation results on a battery sample with the same specifications as battery B.

[0045] 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 (i) the first to nth reference currents, (ii) the first to nth reference voltage ranges, (iii) the first to nth reference SOCs, and (iv) the first to nth reference voltage curves for multi-stage constant-current charging. n is a natural number greater than or equal to 2. The reference current of a later stage may be smaller than the reference current of a earlier stage. Each reference voltage range may be called a "stage".

[0046] 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 can be recognized by 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. The higher-level controller 2 may transmit charging start commands and charging interruption commands to the battery management system 100 in response to input from the vehicle user.

[0047] 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.

[0048] The switch driver 150 is electrically coupled to the control unit 140 and the switch 20. The switch driver 150 is configured to selectively turn 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.

[0049] 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.

[0050] The control unit 140, also called the "battery controller," 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.

[0051] 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.

[0052] The control unit 140 can determine the State of Charge (SOC) of battery B, which indicates the remaining capacity, based on the sensing signal. Known algorithms such as ampere counting, open circuit voltage (OCV)-SOC curves, and Kalman filters can be used to determine the SOC. The SOC of battery B may be referred to as "battery SOC".

[0053] Figure 2 illustrates the correspondence between reference currents and reference voltage ranges recorded in the charging map, and Figure 3 illustrates the correspondence between reference voltage ranges and reference SOCs recorded in the charging map. For the sake of explanation, Figures 2 and 3 show n=4, i.e., the charging map defines the correspondence between 4 reference currents, 4 reference voltage ranges, and 4 reference SOCs.

[0054] The current profile 210 shown in Figure 2 illustrates the correspondence between the first to fourth reference currents I1 to I4 and the first to fourth reference voltage ranges ΔV1 to ΔV4 for a new battery B. The current profile 210 can be recorded in a charge map in a format such as a data table. When k (which may be called the "charge index") is a natural number less than or equal to n, V k-1 and V k Each of these is the kth reference voltage range ΔV kare the lower limit and the upper limit.

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

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

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

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

[0059] The first voltage profile 310 shown in Figure 3 shows the correspondence between the first to fourth reference states of gravity (SOCs) S1 to S4 and the first to fourth reference voltage ranges ΔV1 to ΔV4 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. The first voltage profile 310 includes the first to fourth reference voltage curves. The k-th reference voltage curve corresponds to the k-th reference voltage range ΔV1 to ΔV4 in the first voltage profile 310. k This is the corresponding part.

[0060] S k The battery voltage of a new battery B is the kth reference current I k Constant current charging using the k reference voltage V k This shows the State of Charge (SOC) of battery B when it reaches this point.

[0061] On the other hand, as battery B gradually degrades, the capacity loss of battery B increases, resulting in a higher voltage rise for the same charging capacity compared to a new battery. This affects the k-th reference current I in the charging map. k During constant current charging using, the SOC is the k-th reference SOC S k Before reaching the kth 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 correspondence between the battery voltage change history and the state of charge change history, 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 voltage ranges ΔV1 to ΔV4, without applying the battery management method according to the present invention (see Figure 4). Referring to the second voltage profile 320, Z k The battery voltage of the degraded battery B is the kth reference voltage V k The battery SOC when it reaches the k-th reference SOC S k We can confirm that they are smaller. That is, S1 > Z1, S2 > Z2, S3 > Z3, and S4 > Z4.

[0062] kth reference current Ik During constant current charging using this method, the State of Charge (SOC) of battery B is the k-th reference SOC S k Before reaching the kth reference voltage V k The fact that it reached this point means that in the next multi-stage constant current charging stage, the k-th reference current I k This indicates that the kth reference current I needs to be reduced. k Considering the voltage history and / or SOC history monitored during charging, the k-th reference current I k The degree of decrease can be determined.

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

[0064] Referring to the third voltage profile 330, the control unit 140 controls the k-th reference current I k During constant current charging using this method, the battery voltage, battery current, and SOC are monitored at set time intervals (e.g., 0.001 seconds). The control unit 140 determines that the SOC of battery B is the k-th reference SOC 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 kth reference SOC of battery B k Until it reaches the kth reference voltage V, battery B kConstant voltage charging is performed. For example, after constant current charging using the second reference current I2 over the voltage range V1 to V2, battery B is charged at the same charging voltage as the kth reference voltage V2 until the state of charge (SOC) of battery B reaches the second reference SOC S2. kth reference voltage range ΔV k During constant voltage charging using this method, the battery voltage gradually increases, causing the battery current to gradually decrease. The control unit 140 controls the kth reference voltage range ΔV k During constant voltage charging using this method, the battery voltage, battery current, and SOC can be monitored at set intervals.

[0065] The control unit 140 controls the kth reference voltage range ΔV k Based on the battery voltage, battery current, and SOC monitored during charging, the k-th reference current I of the charging map, including the current profile 210 in Figure 2 and the first voltage profile 310 in Figure 3, is used. k It can be updated. Current I of 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] Specifically, the control unit 140 can determine at least one of the average voltage and average SOC of the k-th reference voltage curve. The average voltage of the k-th reference voltage curve is the k-th reference voltage range ΔV in the first voltage profile 310. k This is the average of the battery voltage over a certain period. The average SOC of the k-th reference voltage curve is the k-th reference voltage range ΔV in the first voltage profile 310. k This is the average SOC over a certain period.

[0067] The control unit 140 can determine at least one of the average voltage and average SOC of the k-th measured voltage curve. The average voltage of the k-th measured voltage curve is within the k-th reference voltage range ΔV in the third voltage profile 330. k This is the average of the battery voltage over a certain period. The average SOC of the k-th measured voltage curve is the k-th reference voltage range ΔV in the third voltage profile 330. k This is the average SOC over a certain period.

[0068] Subsequently, the control unit 140 determines the kth reference current I of the charge map based on at least one of the average voltage and average SOC of the kth reference voltage curve and at least one of the average voltage and average SOC of the kth measured voltage curve. k It can be updated.

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

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

[0071] Alternatively, the control unit 140 adjusts the k-th reference current I based on the first and second ratios. k The control unit 140 can update the first ratio, the second ratio, and the k-th reference current I. k The same as the product of the k-th reference current I k It can be updated.

[0072] Alternatively, the control unit 140 determines the k-th reference SOC S k Based on the third percentage of the SOC of interest (which is less than 1), the k-th reference current I k The control unit 140 can update the third ratio and the k-th reference current I k The same as the product of the k-th reference current I k This can be updated. The SOC of interest is when the battery voltage is the kth reference voltage V kThe SOC U of battery B at the point it reaches k It may be identical to that.

[0073] On the other hand, the charging stages using the aforementioned battery management method are frequently not performed for a portion of the reference voltage range ΔV1 to ΔV4. For example, referring to Figures 2 and 3, if the charging stage using the charging map is started when the battery voltage is higher than V0, the first measured voltage curve covering the entire first reference voltage range ΔV1 cannot be obtained, making it impossible to update the first reference current I1 using the aforementioned method. In another example, if the vehicle user disconnects the charging cable from the electric vehicle 1 before the battery voltage reaches V4, the fourth measured voltage curve covering the entire fourth reference voltage range ΔV4 cannot be obtained, making it impossible to update the fourth reference current I4.

[0074] To solve the aforementioned problems, the control unit 140 may update the reference currents for each of the remaining reference voltage ranges based on update information for at least one reference voltage range from all of the reference voltage ranges ΔV1 to ΔV4 for which a measured voltage curve has been acquired, when charging starts when the battery voltage is greater than V0 or when charging ends when the battery voltage is less than V4.

[0075] k-th reference voltage range ΔV k Corresponding k-th reference current I k 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 may 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.

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

Number

[0077] In the above formula, x is a natural number not exceeding 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 ratio of the average of the i-th to j-th updated reference currents I i ~I j to the i-th to j-th reference currents I 1i ~I 1j .

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

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

[0080] Referring to Figures 1 to 4, in step S410, the control unit 140 determines the kth reference voltage range ΔV to which the battery voltage of battery B belongs. k Corresponding k-th reference current I k Select from the charging map. For example, if the battery voltage is between V1 and V2, the second reference current I2 will be selected.

[0081] In step S420, the control unit 140 sets the k-th reference current I k The charging circuit 50 is instructed to perform constant current charging using the k-th reference current I. k By supplying this to battery B as the charging current, the k-th reference current I k Start constant current charging using this method.

[0082] In step S430, the control unit 140 determines that the battery SOC is the k-th reference SOC S k Before reaching the kth reference voltage V k It is determined whether or not the condition has been reached. If the value of step S440 is "yes", proceed to step S450. If the value of step S430 is "no", after a predetermined time, step S430 is performed again.

[0083] In step S440, the control unit 140 supplies the k-th reference voltage V to the charging circuit 50. k The system commands constant voltage charging using the following: This causes the charging circuit 50 to use the k-th reference current I k The constant current charging is terminated using the k-th reference voltage V k The same charging voltage is supplied to battery B.

[0084] In step S450, the control unit 140 determines that the battery SOC is the k-th reference SOC S kDetermine whether the condition has been reached. If the value of step S450 is "yes", proceed to step S460. If the value of step S450 is "no", step S450 is repeated after a predetermined time.

[0085] In step S460, the control unit 140 determines the k-th measurement voltage curve. The k-th measurement voltage curve is determined by the k-th reference current I k This shows the relationship between battery voltage and battery state of charge (SOC) over the charging period using constant current charging.

[0086] In step S470, the control unit 140 determines that the voltage range of the k-th measured voltage curve is within the k-th reference voltage range ΔV k Determine whether it is the same as the previous value. If the value in step S470 is "yes", proceed to step S480. If the value in step S470 is "no", proceed to step S490. For example, if the battery voltage is greater than V0 and less than V1, and constant current charging is performed with the first reference current I1, the value in step S470 will be "no".

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

[0088] In step S490, the control unit 140 determines whether the charge index k is the same as n. That is, the control unit 140 determines the last reference voltage range ΔV defined by the charge map. n The procedure determines whether charging is complete. If the value in step S490 is "no", the charging index k is increased by 1 in step S492, and then the procedure returns to step S430. If the value in step S490 is "yes", the procedure in Figure 4 ends.

[0089] The method of FIG. 4 can be started in response to a charging start command when a predetermined update condition is satisfied. The update condition is for preventing the charge maps 210 and 310 from being updated too frequently without necessity. For example, it is shown that the degradation degree of the battery B has increased above a certain level, such as the accumulated capacity of the battery B has increased by more than a first critical value (e.g., 100 Ah [ampere - hour]) compared to the accumulated capacity at the time of the previous update, the number of cycles of the battery B has increased by more than a second critical value (e.g., 50 times) compared to the number of cycles at the time of the previous update, the capacity retention rate of the battery B has decreased by more than a third critical value (e.g., 5%) compared to the capacity retention rate at the time of the previous update, or the result is more than a critical time (e.g., one month) from the time of the previous update, etc.

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

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

[0092] [[ID=2⑨]] In step S520, the control unit 140 determines the first to n - th reference currents I1 to I nOf these, the i-th to j-th reference current I i ~I j The remaining reference currents, after removing the specified value, are each multiplied by their respective average ratios, and the remaining reference currents are updated accordingly.

[0093] 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.

[0094] 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.

[0095] 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 sensing unit that generates a sensing signal indicating the battery voltage of the battery, A memory unit that stores a charging map in which the correspondence between the first to nth reference currents for multi-stage constant current charging and the first to nth reference voltage ranges is recorded, The charging circuit connected to the battery is instructed to perform constant current charging using a k-reference current corresponding to the k-reference voltage range to which the battery voltage belongs. The control unit includes, in response to the battery voltage reaching the upper limit of the k-reference voltage range during constant current charging, commands the charging circuit to perform constant voltage charging using the upper limit of the k-reference voltage range, and when the SOC of the battery reaches the upper limit of the k-reference SOC range due to the constant voltage charging, starts constant current charging using the k+1-reference current corresponding to the k+1-reference voltage range. Battery management system.

2. The control unit, After the start of constant current charging using the k+1 reference current corresponding to the k+1 reference voltage range, when the battery voltage reaches the upper limit of the k+1 reference voltage 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 voltage of the battery reaches the upper limit of the k+1 reference voltage range.

3. The control unit, The battery management system according to claim 1, which updates the charging map based on a k-th measured voltage curve and a k-reference voltage curve that show the correspondence between the battery voltage and the battery SOC over the charging period of the constant current charging using the k-reference current.

4. The control unit, The battery management system according to claim 3, which updates the k reference current based on the ratio of the average SOC of the k measured voltage curve to the average SOC of the k reference voltage curve.

5. The control unit, The battery management system according to claim 3, which updates the k reference current based on the ratio of the average voltage of the k reference voltage curve to the average voltage of the k measurement voltage curve.

6. The control unit, The battery management system according to claim 3, which updates the k reference current based on a first ratio of the average SOC of the k measured voltage curve to the average SOC of the k reference voltage curve and a second ratio of the average voltage of the k reference voltage curve to the average voltage of the k measured voltage curve.

7. The control unit, The k-reference current is updated based on the ratio of the SOC of interest to the k-reference SOC. The battery management system according to claim 3, wherein the SOC of interest is the SOC of the battery at the point when the battery voltage reaches the upper limit of the k reference voltage range.

8. The control unit, The battery management system according to claim 3, 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. Based on a charging map that records the correspondence between the first to nth reference currents and the first to nth reference voltage ranges for multi-stage constant current charging, the charging circuit connected to the battery is instructed to perform constant current charging using the kth reference current corresponding to the kth reference voltage range to which the battery voltage of the battery belongs. The process includes the step of, during constant current charging, in response to the battery voltage reaching the upper limit of the k reference voltage range, commanding the charging circuit to perform constant voltage charging using the upper limit of the k reference voltage range, and when the SOC of the battery reaches the upper limit of the k reference SOC range due to the constant voltage charging, starting constant current charging using the k+1 reference current corresponding to the k+1 reference voltage range. Battery management methods.

12. After starting constant current charging using the k+1 reference current corresponding to the k+1 reference voltage range, the process further includes a step of switching from constant current charging to constant voltage charging using the k+1 reference voltage when the battery voltage reaches the upper limit of the k+1 reference voltage range. The battery management method according to claim 11, wherein the k+1 reference voltage is the voltage at which the voltage of the battery reaches the upper limit of the k+1 reference voltage range.

13. The battery management method according to claim 11, further comprising the step of updating the charging map by comparing a k-th measured voltage curve showing the correspondence between the battery voltage and the battery's SOC over the charging period of the constant current charging using the k-reference current with the k-reference voltage curve.

14. The step of updating the aforementioned charging map is: The battery management method according to claim 13, wherein the k reference current is updated based on the ratio of the average SOC of the k measured voltage curve to the average SOC of the k reference voltage curve.

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