Charging control method and device

Abstract

To provide a charging control method.SOLUTION: A charging control method includes steps of: determining, as a first value, a charging completion voltage of constant current charging or constant power charging on the basis of a target charge energy of a battery; before the voltage value of the battery reaches the first value, determining whether or not a time point when the voltage value of the battery reaches the first value is predicted to be around a minimum point of the battery voltage increase rate during the constant current charging or constant power charging; and maintaining or changing the charging completion voltage in accordance with the determination result.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a charge control method and apparatus for controlling the end-of-charge voltage based on the voltage profile of a battery. [Background technology]

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries that can be charged and discharged. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as motor drive power sources and power storage batteries in hybrid vehicles, electric vehicles, and the like. Such secondary batteries include an electrode assembly consisting of a positive electrode and a negative electrode, a case that houses the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] Secondary batteries can be continuously used by recharging after discharge, but the usability and performance of secondary batteries, such as charging time and deterioration amount, vary depending on the charging method. Therefore, efforts are being made to improve charging methods for secondary batteries.

[0004] The foregoing information disclosed in this Background of the Invention section is intended solely to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2011-0039677 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a method and apparatus for controlling the end-of-charge voltage based on the voltage profile of the battery.

[0007] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention provided below. [Means for solving the problem]

[0008] A charging control method according to one embodiment of the present invention for solving the technical problems includes the steps of determining a charging completion voltage of constant current charging or constant power charging as a first value based on a target charging energy of a battery, determining whether the point at which the battery voltage value reaches the first value is predicted to be near a minimum point of the battery voltage increase rate during constant current charging or constant power charging, before the battery voltage value reaches the first value, and maintaining or changing the charging completion voltage based on the determination result.

[0009] According to one embodiment, the step of determining whether the battery voltage increase rate is predicted to be near a local minimum includes the steps of: calculating at least one of a second-order differential value or a third-order differential value of the battery voltage based on determining that the battery voltage value will reach a value obtained by subtracting a first predetermined value from a first value while constant current charging or constant power charging is being performed; and determining whether the point at which the battery voltage value will reach the first value is predicted to be near a local minimum point of the battery voltage increase rate based on at least one of the second-order differential value or the third-order differential value.

[0010] According to one embodiment, the step of determining whether the battery voltage increase rate is predicted to be near a minimum point includes the steps of calculating a second derivative of the battery voltage based on determining that the battery voltage value will reach a value obtained by subtracting a first predetermined value from a first value during constant current charging or constant power charging, and determining whether the second derivative is positive (greater than 0).

[0011] According to one embodiment, the step of determining whether the time point at which the battery voltage increase rate is predicted to be near a local minimum point further includes the step of determining that the time point at which the battery voltage value reaches the first value is not predicted to be near a local minimum point at which the battery voltage increase rate is predicted to be near a local minimum point based on determining that the second derivative value is positive.

[0012] According to one embodiment, the step of determining whether the battery voltage increase rate is predicted to be near a minimum point further includes the steps of calculating a third derivative of the battery voltage based on determining that the second derivative is not positive, and determining whether the third derivative is within a predetermined range.

[0013] According to one embodiment, determining whether the third derivative value is within a predetermined range includes determining whether the third derivative value is greater than or equal to a second predetermined value.

[0014] According to an embodiment, the step of determining whether the time point at which the battery voltage increase rate is predicted to be near a local minimum point further includes the step of determining that the time point at which the battery voltage value reaches the first value is not predicted to be near a local minimum point at which the battery voltage increase rate is predicted to be near a local minimum point based on determining that the third derivative value is not within a predetermined range.

[0015] According to an embodiment, the step of determining whether the time point at which the battery voltage increase rate is predicted to be near a local minimum point further includes the step of determining that the time point at which the battery voltage value reaches the first value is predicted to be near a local minimum point at which the battery voltage increase rate is predicted to be near a local minimum point based on determining that the third derivative value is within a predetermined range.

[0016] According to one embodiment, maintaining or changing the end-of-charge voltage includes maintaining the end-of-charge voltage as the first value based on determining that the time when the battery's voltage value reaches the first value is not predicted to be near a local minimum point in the battery's voltage increase rate.

[0017] According to one embodiment, maintaining or changing the end-of-charge voltage includes changing the end-of-charge voltage to a second value based on determining that the time when the battery voltage value reaches the first value is predicted to be near a minimum point in the battery voltage increase rate.

[0018] According to one embodiment, if the value obtained by adding the third predetermined value to the first value is equal to or less than the upper operating voltage limit of the battery, the second value is equal to the first value plus the third predetermined value, and if the value obtained by adding the third predetermined value to the first value is greater than the upper operating voltage limit of the battery, the second value is the upper operating voltage limit.

[0019] According to one embodiment, the second derivative value includes a value obtained by differentiating the battery voltage twice with respect to the charge amount or time, and the third derivative value includes a value obtained by differentiating the battery voltage three times with respect to the charge amount or time.

[0020] According to one embodiment, the method further includes switching to constant voltage charging based on determining that the voltage value of the battery reaches a charge completion voltage.

[0021] A charging control device according to one embodiment of the present invention for solving the technical problems includes a memory that stores one or more instructions; and a processor that is configured to execute the one or more stored instructions to determine a charging completion voltage of constant current charging or constant power charging as a first value based on a target charging energy of a battery, determine whether a point at which the battery voltage value reaches the first value is predicted to be near a minimum point of the battery voltage increase rate during constant current charging or constant power charging before the battery voltage value reaches the first value, and maintain or change the charging completion voltage based on the determination result.

[0022] According to one embodiment, the processor is further configured to calculate at least one of a second-order differential value or a third-order differential value of the battery voltage based on determining that the battery voltage value reaches a value obtained by subtracting a first predetermined value from a first value while performing constant current charging or constant power charging, and to determine, based on the at least one of the second-order differential value or the third-order differential value, whether the time point at which the battery voltage value reaches the first value is predicted to be near a minimum point of the battery voltage increase rate.

[0023] According to one embodiment, the processor is further configured to calculate a second derivative value of the battery voltage based on determining that the battery voltage value reaches a value obtained by subtracting a first predetermined value from the first value while performing constant current charging or constant power charging, and to determine whether the second derivative value is positive.

[0024] According to one embodiment, the processor is further configured to determine, based on determining that the second derivative value is positive, that the time point at which the voltage value of the battery reaches the first value is not predicted to be near a local minimum point in the rate of increase of the voltage of the battery.

[0025] According to one embodiment, the processor is further configured to calculate a third derivative of the battery voltage based on determining that the second derivative is not positive, and determine whether the third derivative is within a predetermined range.

[0026] According to one embodiment, the processor is further configured to determine, based on determining that the third derivative value is not within the predetermined range, that the time point at which the voltage value of the battery reaches the first value is not predicted to be near a local minimum point of the battery voltage increase rate.

[0027] According to one embodiment, the processor is further configured to determine, based on determining that the third derivative value is within a predetermined range, that the time point at which the voltage value of the battery reaches the first value is predicted to be near a local minimum point of the battery voltage increase rate. [Effects of the Invention]

[0028] According to some embodiments of the present invention, when performing constant voltage charging, resources such as charging time can be reduced by setting the charge completion voltage to avoid voltage regions that take a long charging time, i.e., voltage regions where the voltage increase rate is low.

[0029] However, the effects obtained by the present invention are not limited to the effects described above, and other technical effects not mentioned should be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0030] The following drawings and the like of this application illustrate preferred embodiments of the present invention and, together with the detailed description of the invention to be given later, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in these drawings. [Figure 1] FIG. 1 is a perspective view illustrating an example of a battery cell according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a perspective view illustrating an example of a battery module according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a perspective view illustrating an example of a battery pack according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a perspective view illustrating an example of a battery pack according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a diagram illustrating an example of a charging method according to an embodiment of the present disclosure. [Figure 6] 1 is a configuration diagram illustrating an example of a charging system according to an embodiment of the present disclosure. [Figure 7] FIG. 10 shows examples of charging profiles with different end-of-charge voltages. [Figure 8] FIG. 8 shows an example of a voltage profile for the same battery as the example of FIG. 7. [Figure 9] 1 is a flowchart illustrating an example of a charge control method according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0031] Preferred embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. First, the terms and phrases used in this specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed in a way that is consistent with the technical concept of the present invention, based on the principle that an inventor can appropriately define the concepts of terms in order to best describe his or her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely some preferred embodiments of the present invention, do not represent the entire technical concept of the present invention, and that various equivalents and modifications may exist as of the time of filing this application.

[0032] Furthermore, as used herein, "comprise," "comprising," "include," "including" specifies the presence of a stated shape, number, step, operation, member, element, and / or group, but does not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups. Furthermore, when describing an embodiment of the present invention, "may" and "may be" can include "one or more embodiments of the present invention."

[0033] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals are used to refer to the same components in different embodiments.

[0034] A statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, being substantially identical can include cases where there is a deviation that is considered low in the art, for example, a deviation of 5% or less. Furthermore, a statement that a certain parameter is uniform in a given region can mean that the parameter is uniform on average.

[0035] Although terms such as "first" and "second" are used to describe various components, it is understood that these components are not limited by these terms. These terms are merely used to distinguish one component from another, and unless otherwise specified, a first component can be a second component.

[0036] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0037] The phrase "above (or below)" a component or "above (or below)" a component means that the component is not only placed in contact with the upper surface (or lower surface) of the component, but also means that other components may be interposed between the component and the component placed above (or below) the component.

[0038] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components. Furthermore, when a part is said to be electrically coupled to another part, this includes not only a direct connection but also a connection via another element therebetween.

[0039] Throughout the specification, "A and / or B" means A or B, or A and B, unless specifically stated to the contrary. That is, "and / or" includes all or any combination of the listed items. "C through D" means at least C and at most D, unless specifically stated to the contrary.

[0040] Fig. 1 is a perspective view showing an example of a battery cell 100 according to an embodiment of the present disclosure. As shown in Fig. 1, the battery cell 100 may include an electrode assembly including electrodes (e.g., at least one electrode assembly formed by winding or stacking a positive electrode and a negative electrode with an insulating separator sandwiched between them), a case 110 in which the electrode assembly is housed, and a cap plate 120 coupled to an opening of the case 110. The battery cell 100 shown in Fig. 1 may be a type of secondary battery.

[0041] The positive and negative electrodes may include a coated portion, which is a region where an active material is applied to a current collector made of a thin metal foil, and an uncoated portion, which is a region where the active material is not applied. The positive and negative electrodes are wound with an insulating separator sandwiched between them. However, the present invention is not limited thereto, and the electrode assembly may have a structure in which positive and negative electrodes made of multiple sheets are alternately stacked with a separator sandwiched between them. Alternatively, the electrode assembly may have any structure including electrodes.

[0042] The case 110 forms the overall appearance of the battery cell 100 and may be made of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. The case 110 may also provide a space for accommodating an electrode assembly. In FIG. 1, the case 110 is shown as a prismatic case and the battery cell 100 is shown as a prismatic battery cell, but this is not intended to be limiting. The battery cell 100 may be a battery cell of any shape, such as a prismatic, cylindrical, or pouch shape.

[0043] The cap plate 120 is coupled to the opening of the case 110 to seal the case 110. The case 110 and the cap plate 120 may be made of a conductive material. According to one embodiment, the top of the case 110 is open, and the cap plate 120 seals the open top of the case 110.

[0044] A positive electrode terminal 130_1 electrically connected to the positive electrode and a negative electrode terminal 130_2 electrically connected to the negative electrode are coupled to the cap plate 120. For example, the positive electrode terminal 130_1 and the negative electrode terminal 130_2 may be installed to protrude outward through the cap plate 120. The positions of the positive electrode terminal 130_1 and the negative electrode terminal 130_2 may be changed.

[0045] According to one embodiment, a vent portion 140 may be formed on at least one surface of the battery cell 100 (for example, in the figure, the top surface of the battery cell 100, i.e., the cap plate 120). The vent portion 140 may be configured to open when an internal pressure equal to or greater than a predetermined critical pressure is detected from the battery cell 100. Additionally or alternatively, the vent portion 140 may be configured to open when an internal temperature exceeds a predetermined critical temperature. With this configuration, the vent portion 140 may prevent the battery cell 100 from exploding or prevent a chain reaction of heat generation in other battery cells arranged around the battery cell 100.

[0046] In one embodiment, the cap plate 120 may include an electrolyte injection hole 150. For example, the electrolyte injection hole 150 may be a through-hole formed in the cap plate 120, and may be formed to inject an electrolyte into the case 110 after the cap plate 120 is coupled to and sealed with the opening of the case 110. The electrolyte injection hole 150 is sealed with a sealing member after the electrolyte is injected.

[0047] The battery cell 100 may be a lithium battery cell, a sodium battery cell, or the like. However, the scope of the present disclosure is not limited thereto, and the battery cell 100 includes all batteries that can repeatedly provide electricity through charging and discharging. In one embodiment, when the battery cell 100 is a lithium battery cell, it can be used in electric vehicles (EVs) due to its excellent life characteristics and high rate characteristics. For example, it can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). Lithium battery cells can also be used in fields requiring large amounts of power storage, such as electric bicycles and power tools.

[0048] FIG. 2 is a perspective view illustrating an example of a battery module 1000 according to an embodiment of the present disclosure.

[0049] Although the battery pack and the battery module are described below as distinct concepts, the present disclosure is not limited thereto.

[0050] 2, a battery module 1000 according to the present invention includes a plurality of battery cells 10 arranged in one direction and each having terminal portions 11 and 12, a connection tab 20 connecting a battery cell 10a to an adjacent battery cell 10b, and a protection circuit module 30 having one end connected to the connection tab 20. The protection circuit module 30 may be a battery management system (BMS). The connection tab 20 includes a body portion contacting the terminal portions 11 and 12 between the adjacent battery cells 10a and 10b, and an extension portion extending from the body portion and connected to the protection circuit module 30. The connection tab 20 may be a bus bar.

[0051] First, the battery cell 10 may include a battery case, an electrode assembly housed within the battery case, and an electrolyte. The electrode assembly and the electrolyte react electrochemically to generate energy. One side of the battery cell 10 is provided with terminals 11 and 12 electrically connected to a connection tab 20 and a vent 13 serving as a passage for discharging gas generated from the battery cell. The terminals 11 and 12 of the battery cell 10 may be a positive terminal 11 and a negative terminal 12 having opposite polarities, and the terminals 11 and 12 of adjacent battery cells 10a and 10b may be electrically connected in series or parallel via a connection tab 20, which will be described later. While the above description has been given using a series connection as an example, the present invention is not limited to this structure and various connection structures may be adopted as needed. In addition, the number and arrangement of the battery cells are not limited to the structure shown in FIG. 2 and may be changed as needed.

[0052] The plurality of battery cells 10 are arranged in one direction with the wide surfaces of the battery cells 10 facing each other, and the arranged plurality of battery cells 10 are fixed by housings 61, 62, 63, and 64. The housings 61, 62, 63, and 64 may include a pair of end plates 61, 62 facing the wide surfaces of the battery cells 10, and a side plate 63 and a bottom plate 64 connecting the pair of end plates 61, 62. The side plate 63 supports the side surfaces of the battery cells 10, and the bottom plate 64 supports the bottom surfaces of the battery cells 10. In addition, the pair of end plates 61, 62, the side plate 63, and the bottom plate 64 may be connected by members such as bolts 65.

[0053] The protection circuit module 30 includes electronic components and a protection circuit mounted thereon and is electrically connected to the connection tab 20 (described later). The protection circuit module 30 includes a first protection circuit module 30a and a second protection circuit module 30b extending from different positions along the direction in which the plurality of battery cells 10 are arranged. The first protection circuit module 30a and the second protection circuit module 30b are spaced apart from each other but parallel to each other, and are electrically connected to the adjacent connection tab 20. For example, the first protection circuit module 30a extends from one side of the upper portions of the plurality of battery cells 10 along the direction in which the plurality of battery cells 10 are arranged, and the second protection circuit module 30b extends from the other side of the upper portions of the plurality of battery cells 10 along the direction in which the plurality of battery cells 10 are arranged. The second protection circuit module 30b is spaced apart from the first protection circuit module 30a by a predetermined distance but parallel to the first protection circuit module 30a. In this way, the two protection circuit modules are arranged parallel to each other and spaced apart in the direction in which the plurality of battery cells are arranged, thereby minimizing the area of ​​the PCB (Printed Circuit Board) that constitutes the protection circuit module. By configuring the protection circuit module as two separate protection circuit modules, unnecessary PCB area is minimized. The first protection circuit module 30a and the second protection circuit module 30b can be connected to each other by a conductive connecting member 50. One side of the connecting member 50 is connected to the first protection circuit module 30a, and the other side is connected to the second protection circuit module 30b, thereby establishing an electrical connection between the two protection circuit modules.

[0054] The aforementioned connections can be made by any one of the following methods: soldering, resistance welding, laser welding or projection welding.

[0055] The connecting member 50 may be, for example, an electric wire. The connecting member 50 may also be made of an elastic or flexible material. The connecting member 50 can be used to check and manage whether the voltage, temperature, and current of the plurality of battery cells 10 are normal. That is, the information on the voltage, current, temperature, etc. received by the first protection circuit module from the connecting tap adjacent thereto and the information on the voltage, current, and temperature received by the second protection circuit module from the connecting tap adjacent thereto can be integrated and managed by the protection circuit module through the connecting member.

[0056] In addition, when the battery cell 10 expands, the elasticity or flexibility of the connecting member 50 absorbs the impact, thereby preventing damage to the first and second protection circuit modules 30a and 30b.

[0057] Furthermore, the shape and structure of the connecting member 50 are not limited to the shape shown in FIG.

[0058] As described above, the protection circuit module 30 includes the first and second protection circuit modules 30a and 30b, thereby minimizing the area of ​​the PCB constituting the protection circuit module and securing space within the battery module. This not only simplifies the fastening operation of connecting the connection tap 20 and the protection circuit module 30, but also facilitates repairs when an abnormality is detected in the battery module, thereby improving work efficiency.

[0059] 3 and 4 are perspective views illustrating an example of a battery pack according to an embodiment of the present disclosure. The battery pack may include a number of battery modules 1000 and a housing 2000 for accommodating the number of battery modules 1000. For example, the housing 2000 may include first and second housings 2010 and 2020 coupled to each other so as to face each other with the number of battery modules 1000 interposed therebetween.

[0060] According to one embodiment, in a battery pack, a stacked cell stack may constitute one module 1000 instead of a battery module. One cell stack may include a plurality of battery cells. The plurality of battery cells in the cell stack may be arranged in one direction with their wide surfaces facing each other. In one embodiment, each battery cell may include a vent portion on its upper surface. For example, the battery cells may be, but are not limited to, the battery cells shown in FIG. 1. The number and arrangement of the cell stack and battery cells are not limited to the structures shown in FIGS. 3 and 4 and may be appropriately changed as needed.

[0061] A plurality of battery modules 1000 or cell stacks can be electrically connected to each other using bus bars 3000, and a plurality of battery modules 1000 can be electrically connected to each other in a series / parallel or mixed series-parallel manner to obtain the required electrical output.

[0062] The secondary battery cells generate a large amount of heat during charging / discharging. The generated heat accumulates in the secondary battery cells, accelerating deterioration of the secondary battery cells. Therefore, the secondary battery pack further includes a cooling member to suppress deterioration of the secondary battery cells. The cooling member is provided at a lower portion of the accommodation space including the secondary battery cells, but is not limited thereto, and may be provided at an upper portion or a side portion depending on the secondary battery pack.

[0063] In each secondary battery cell, exhaust gas generated in the secondary battery cell under abnormal operating conditions known as thermal runaway or a thermal event may be discharged to the outside of the secondary battery cell. The secondary battery pack or secondary battery module may be provided with an exhaust port for discharging the exhaust gas to prevent damage to the secondary battery pack or module due to the exhaust gas.

[0064] The secondary battery pack may include a secondary battery and a secondary battery management system (BMS) for managing the secondary battery. The secondary battery management system may include a detection device, a balancing device, and a control device. The secondary battery module may include a plurality of cells connected to each other in series or parallel. The secondary battery modules may be connected to each other in series or parallel.

[0065] The detection device can sense the status (voltage, current, temperature, etc.) of the secondary battery to detect status information indicating the status of the secondary battery. The detection device can detect the voltage of each cell or each secondary battery module constituting the secondary battery. The detection device can also detect the current flowing through each secondary battery module constituting the secondary battery module or secondary battery pack. The detection device can also detect the temperature of the cell and / or module at at least one point of the secondary battery and / or the ambient temperature.

[0066] The balancing device may perform a balancing operation of the secondary battery modules and / or cell groups constituting the secondary battery. The control device may receive status information (e.g., voltage, current, temperature) of the secondary battery modules from the detection device. The control device may monitor and calculate the status (e.g., voltage, current, temperature, SOC (State of Charge), SOH (State of Health)) of the secondary battery modules based on the status information received from the detection device. The control device may also perform control functions (e.g., temperature control, balancing control, charge / discharge control, etc.) and protection functions (e.g., over-discharge prevention, over-charge prevention, over-current prevention, short circuit prevention, fire extinguishing function, etc.) based on the status monitoring results. The control device may also perform wired or wireless communication functions with external devices (e.g., upper controllers, vehicles, chargers, PCS, etc.) of the secondary battery pack.

[0067] The control device may also control the charging / discharging operation and protection operation of the secondary battery, and for this purpose, the control device may include a charging / discharging control unit, a balancing control unit, and a protection unit.

[0068] The secondary battery management system is a system that monitors the status of the secondary battery and performs diagnostic, control, communication, and protection functions. It can calculate the charge / discharge status, calculate the life or state of health (SOH) of the secondary battery, cut off power to the secondary battery when necessary (relay control), control thermal management (cooling, heating, etc.), perform high-voltage interlock functions, and detect or calculate insulation and short-circuit status.

[0069] The relay can be a mechanical contact that is turned on and off by the magnetic force of a coil, or a semiconductor switch such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET).

[0070] The relay control is a function that cuts off the power supply from the secondary battery when a problem occurs in the vehicle and secondary battery system, and may include one or more relays and a precharge relay at each of the positive and negative terminals.

[0071] Pre-charge control can prevent the occurrence of inrush current in the high voltage capacitor on the inverter input side when the secondary battery is connected to a load. To prevent this, the pre-charge control can operate the pre-charge relay and connect it to a pre-charge resistor before connecting the main relay when the vehicle is started.

[0072] The high voltage interlock is a circuit that uses a small signal to detect whether all high voltage parts are connected to all vehicle systems, and has the function of forcibly opening a relay if an open occurs in even one point on any loop.

[0073] 5 is a diagram illustrating an example of a charging method according to an embodiment of the present disclosure. According to one embodiment, a secondary battery can be charged using a CCCV charging method. CCCV charging is a charging method in which CC (constant current) charging is performed until the voltage reaches a predetermined voltage (charging completion voltage), and then constant voltage (CV) charging is performed until the amount of current flowing decreases (until the end current value is reached).

[0074] When CC charging is performed, as shown in Figure 5(A), the constant current power supply is switched on and the constant voltage power supply is switched off, causing a constant current I to flow through the secondary battery. During this period, the current I is constant, so Ohm's law (V R = R × I) R On the other hand, the voltage V applied to the secondary battery capacity C is C increases over time. Therefore, the secondary battery voltage V B increases over time.

[0075] Secondary battery voltage V B When the voltage reaches a predetermined value, for example, 4.3 V, the charging mode switches from CC charging to CV charging. When CV charging is performed, as shown in Figure 5 (B), the constant voltage power supply is switched on and the constant current power supply is switched off, so the secondary battery voltage V B is constant. On the other hand, the voltage V applied to the secondary battery capacity C C V increases over time. B =V R +V C To satisfy this, the voltage V applied to the internal resistance R R The voltage V applied to the internal resistance R decreases over time. R As the value decreases, Ohm's law (V R The current I flowing to the secondary battery also decreases due to the load (=R×I).

[0076] When the current I flowing through the secondary battery reaches a predetermined value, for example, about 0.01 C, charging is terminated. When CCCV charging is terminated, all switches are turned off and the current I becomes 0, as shown in Figure 5(C). Therefore, the voltage V applied to the internal resistance R R However, the voltage V applied to the internal resistance R R becomes small enough by CV charging, so even if no further voltage drop occurs across the internal resistance R, the secondary battery voltage V B almost never decreases.

[0077] FIG. 5(D) shows the secondary battery voltage V during CCCV charging and after CCCV charging is completed. B The following shows an example of the secondary battery voltage V B almost never decreases.

[0078] Additionally or alternatively, the secondary battery may be charged using a CPCV charging method. For example, the CPCV charging method may perform CP (constant power) charging until the voltage reaches a predetermined voltage (charge completion voltage), and then perform constant voltage (CV) charging until the amount of current flowing decreases (until the end current value is reached). Hereinafter, for convenience of explanation, charging using a CCCV charging method will be mainly described as an example, but the scope of the present disclosure is not limited thereto, and the charging control method may be applied in the same or similar manner to charging using a CPCV charging method.

[0079] 6 is a block diagram illustrating an example of a charging system according to an embodiment of the present disclosure. As shown in FIG. 6, the charging system may include a battery pack 500 and a charging device 600. The battery pack 500 may include a battery 510 and a charging control device 520. The charging device 600 is electrically connected to the battery 510 to supply power to the battery 510, and the charging control device 520 may control charging, such as determining and / or changing a charging completion voltage.

[0080] The battery 510 may include at least one battery cell (e.g., the battery cell 100 of FIG. 1 ), and the battery cell may be a rechargeable secondary battery. The number and connection method of the battery cells included in the battery 510 may be determined based on the amount of power and voltage required for the battery pack 500. For example, the battery 510 may include multiple battery cells connected in series, parallel, or both series and parallel. As another example, the battery 510 may include only one battery cell. The battery to which the charge control method according to an embodiment of the present disclosure is applied may be the battery 510 or at least one battery cell included in the battery 510.

[0081] The charge controller 520 may be a device for controlling the charging of the battery 510. In one embodiment, the charge controller 520 may refer to or be included in a battery management system (BMS) of the battery pack 500.

[0082] According to one embodiment, the charging controller 520 may include a processor 522 and a memory 524. The processor 522 may control the overall operation for controlling the charging of the battery. For example, the processor 522 may store data in the memory 524, load data stored in the memory 524, and execute instructions (program code) stored in the memory 524. The processor 522 may process computer program instructions by performing arithmetic, logic, and input / output operations for controlling the charging of the battery.

[0083] According to one embodiment, processor 522 may be embodied using a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, etc. In some environments, processor 522 may also refer to an application specific semiconductor (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc. In one embodiment, processor 522 may also refer to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0084] The memory 524 may include any non-transitory computer-readable recording medium. According to one embodiment, the memory 524 may include a permanent mass storage device such as a read only memory (ROM), a disk drive, a solid state drive (SSD), or a flash memory. The memory 524 may store an operating system and at least one program code. For example, the memory 524 may store one or more instructions (program code) for performing a charging control method according to one embodiment of the present invention.

[0085] The memory 524 may store data generated by measuring at least one parameter of the battery 510. For example, the data stored in the memory may include a charge / discharge current, a terminal voltage, and / or a temperature of the battery 510. The memory 524 may store SOC-OCV data, a program code for estimating the SOC of the battery using data generated by measuring at least one parameter of the battery 510. The at least one parameter of the battery 510 refers to a component or variable such as the terminal voltage, charge / discharge current, and / or an ambient temperature of the battery 510.

[0086] According to an embodiment, the charging control device may further include a voltage measurement unit, a current measurement unit, and a temperature measurement unit for measuring at least one parameter of the battery 510. According to an embodiment, the charging control device may further include a communication module for communicating with other devices, such as a charging device or a vehicle electronic control device. The voltage measurement unit may be configured to measure the voltage of the battery 510. The voltage measurement unit may be electrically connected to the processor 522 to exchange electrical signals. According to an embodiment, the voltage measurement unit may measure the voltage across the battery 510 and / or the battery cells at time intervals under the control of the processor 522 and output a signal indicating the magnitude of the measured voltage to the processor 522. In this case, the processor 522 may determine the voltage of the battery 510 and / or the battery cells according to the signal output from the voltage measurement unit. For example, the voltage measurement unit may be implemented using a voltage measurement circuit commonly used in the art.

[0087] The current measuring unit may be configured to measure the current of the battery. The current measuring unit may be electrically connected to the processor 522 to exchange electrical signals. According to one embodiment, the current measuring unit may repeatedly measure the magnitude of the charging current or discharging current of the battery 510 and / or battery cells at time intervals under the control of the processor 522 and output a signal indicating the magnitude of the measured current to the processor 522. In this case, the processor 522 may determine the magnitude of the current according to the signal output from the current measuring unit. For example, the current sensor may be implemented using a Hall sensor or a sense resistor commonly used in the art.

[0088] The temperature measurement unit may be configured to measure the temperature of the battery 510. The temperature measurement unit may be electrically connected to the processor 522 to exchange electrical signals. According to one embodiment, the temperature measurement unit may repeatedly measure the temperature of the secondary battery at time intervals and output a signal indicating the magnitude of the measured temperature to the processor 522. In this case, the processor 522 may determine the temperature of the battery according to the signal output from the temperature measurement unit. For example, the temperature measurement unit may be implemented using a thermocouple commonly used in the art.

[0089] The processor 522 can also estimate the state of charge (SOC) of the battery 510 using at least one of the voltage measurement, current measurement, and temperature measurement for the battery 510. Here, the SOC can be calculated as a value ranging from 0% to 100% that corresponds to the remaining capacity of the battery 510.

[0090] According to one embodiment, the processor 522 may estimate the SOC of the battery 510 by integrating the charging current and discharging current of the battery 510. Here, when charging or discharging of the battery 510 starts, an initial value of the state of charge may be determined using the open circuit voltage (OCV) of the battery 510 measured before the charging or discharging starts. To this end, the processor 522 may estimate the state of charge corresponding to the open circuit voltage of the battery 510 using an SOC-OCV lookup table that defines the state of charge for each open circuit voltage.

[0091] The processor 522 may control charging of the battery 510 based on battery state information acquired by various methods, such as the methods described above. The battery state information may include the voltage, charge / discharge current, temperature, state of charge (SOC), and deterioration amount (e.g., state of health (SOH), resistance increase rate, capacity decrease rate, etc.) of the battery 510.

[0092] According to one embodiment, while performing CCCV charging or CPCV charging, the processor 522 determines an initial charge completion voltage for CC charging or CP charging, and if it is determined that the determined initial charge completion voltage falls within a voltage region where the voltage increase rate is low, the processor 522 can adjust the charge completion voltage upward.

[0093] For example, while performing CCCV charging or CPCV charging, the processor 522 may determine a charge completion voltage for CC charging or CP charging as the first value. For example, the processor 522 may determine the charge completion voltage as the first value based on at least one of battery status information, such as a target charging energy, a temperature of the battery 510, a state of charge, and a deterioration amount.

[0094] Thereafter, during constant current charging or constant power charging, the processor 522 may determine whether the time when the voltage value of the battery 510 will reach the first value (i.e., the charge completion voltage value determined based on the battery state information) is predicted to be near a minimum point of the voltage increase rate of the battery 510 before the voltage value of the battery 510 reaches the first value. If the time when the voltage value of the battery 510 will reach the first value is predicted to be near a minimum point of the voltage increase rate of the battery 510, the processor 522 may change the charge completion voltage to a second value or an upper operating voltage limit. This allows the charge completion voltage to be set while avoiding a voltage region with a low voltage increase rate, thereby reducing resources such as charging time. The process by which the processor 522 determines whether the time when the voltage value of the battery 510 will reach the first value is predicted to be near a minimum point of the voltage increase rate of the battery 510 and the process of changing the charge completion voltage based on the determination result will be described in detail below with reference to FIG. 9.

[0095] The processor 522 can appropriately control the switches included in the battery pack 500 to perform the above-mentioned charging control.

[0096] FIG. 7 is a diagram showing an example charging profile 700 with various charge completion voltages, and FIG. 8 is a diagram showing an example voltage profile 800 for the same battery as the example in FIG. 7. As shown in FIGS. 7 and 8, the example charging profile 700 includes a time-voltage (V) graph and a time-current (I) graph with various charge completion voltages when CCCV charging is performed, and the example voltage profile 800 includes a time-voltage (V) graph and a time-voltage increase rate (V) graph when CCCV charging is performed up to 100% SOC.

[0097]

number

[0098] ) graph included.

[0099] According to the example voltage profile 800 of FIG. 8, when charging the battery, the voltage increase rate (e.g.,

[0100]

number

[0101] It can be seen that low peak sections (P1, P2, P3, minimum points) occur when the voltage v1 is close to the peak section (P1, P2, P3). These peak sections (P1, P2, P3) can occur for a variety of reasons, including phase changes in the battery's internal materials. In these peak sections (P1, P2, P3), the current decrease rate is also low during constant voltage charging. Therefore, if constant voltage charging is performed using voltages (v1, v2, v3) near the peak sections (P1, P2, P3), it may take longer to reach the end current value, which may result in longer charging times.

[0102] According to the example charging profile 700 in Figure 7, when the charge completion voltage is set to a voltage value (v1, v2, v3, 4.159 [V], 4.169 [V] in Figure 7) near the peak section (P1, P2, P3), it can be seen that the constant voltage charging time is particularly long compared to other cases. This tendency can also be confirmed in Table 1 below.

[0103] [Table 1]

[0104] Table 1 shows the results of constant-current charging at various end-of-charge voltages and constant-voltage charging at 1 / 5C or 1 / 50C for the same battery as in the examples of Figures 7 and 8. The first example (end-of-charge voltage: 4.159V, end-of-charge current: 1 / 50C) and the second example (end-of-charge voltage: 4.250V, end-of-charge current: 1 / 5C) show similar capacities (164.4Ah and 164.9Ah, respectively). However, the first example, where the end-of-charge voltage is in the peak section (P1), takes a significantly longer constant-voltage charging time, resulting in an additional 30 minutes of charging time for the first example compared to the second example.

[0105] Since the state in which such peak intervals (P1, P2, P3) are shown varies depending on the battery degradation history and the like, it is very difficult to set the charge completion voltage while avoiding the peak intervals (P1, P2, P3) before charging.

[0106] According to an embodiment of the present disclosure, during charging, the charge control device can determine whether the time when the voltage of the battery reaches the charge completion voltage is predicted to be in the peak intervals (P1, P2, P3) of the voltage increase rate (that is, near the minimum point of the voltage increase rate) based on the voltage profile. When it is determined that the time when the voltage of the battery reaches the charge completion voltage is predicted to be in the peak intervals (P1, P2, P3) of the voltage increase rate (that is, near the minimum point of the voltage increase rate), the charge control device can change the charge completion voltage.

[0107] For example, when the charge completion voltage is set to v3 (corresponding to the peak interval (P3) in FIG. 8), the charge control device can determine whether the peak intervals (P1, P2, P3) of the voltage increase rate are predicted to come immediately based on the voltage profile state at the time point ta (<t3) when the voltage value of the battery reaches va (<v3). When it is predicted that the peak intervals (P1, P2, P3) of the voltage increase rate will come immediately, the charge control device can adjust the charge completion voltage upward to vb (≧v3). Thereby, the charge completion voltage can be set while avoiding the voltage region of the peak intervals (P1, P2, P3) of the voltage increase rate (that is, near the minimum point of the voltage increase rate), and resources such as the charging time can be reduced. The process by which the charge control device adjusts the charge completion voltage will be described in detail later with reference to FIG. 9.

[0108] 9 is a flowchart illustrating an example of a charging control method 900 according to an embodiment of the present disclosure. According to one embodiment, the charging control method 900 may begin by a processor (e.g., at least one processor of a charging control device) determining a charging completion voltage for constant current charging or constant power charging as a first value based on a target charging energy (S910). For example, the processor may determine the charging completion voltage for constant current charging or constant power charging as the first value based on at least a portion of battery state information including the target charging energy and the temperature, state of charge (SOC), and degradation amount (e.g., state of health (SOH), resistance increase rate, capacity decrease rate, etc.) of the battery to be charged.

[0109] Subsequently, when performing constant current charging or constant power charging, the processor can determine, before the battery voltage value reaches the first value, whether the time when the battery voltage value reaches the first value is predicted to be near a minimum point of the battery voltage increase rate. For example, the processor can calculate at least one of a second-order differential value or a third-order differential value of the battery voltage, and determine, based on the calculated at least one of a second-order differential value or a third-order differential value, whether the time when the battery voltage value reaches the first value is predicted to be near a minimum point of the battery voltage increase rate. Here, the second-order differential value can include a value obtained by differentiating the battery voltage twice with respect to the charge amount and / or time. As a specific example, the second-order differential value can be a value obtained by differentiating the battery voltage increase rate (e.g.,

[0110]

number

[0111] etc.) once differentiated with respect to time and / or charge amount (e.g.,

[0112]

number

[0113] or

[0114]

number

[0115] The third derivative may include a value obtained by differentiating the battery voltage three times with respect to the charge amount and / or time. As a specific example, the third derivative may be a value obtained by differentiating the battery voltage increase rate (e.g.,

[0116]

number

[0117] etc.) twice differentiated with respect to time and / or charge amount (e.g.,

[0118]

number

[0119] or

[0120]

number

[0121] ), i.e., the second derivative of the voltage increase rate.

[0122] As a specific example, first, constant current charging or constant voltage charging can be performed until the battery voltage value reaches a value obtained by subtracting a first predetermined value (for example, a positive real number a, for example, 0.05 [V]) from the first value (S920). Based on the determination that the battery voltage value reaches the value obtained by subtracting the first predetermined value from the first value, the processor calculates a second derivative value of the battery voltage (for example,

[0123]

number

[0124] ) and determines whether the calculated second derivative is positive (greater than 0) (S930). That is, the processor can start the determination immediately before the battery voltage reaches the initially set end-of-charge voltage.

[0125] The second derivative of the voltage is positive because the voltage increase rate (e.g.,

[0126]

number

[0127] ) is increasing. That is, since the current voltage increase rate is increasing, it is predicted that the time when the battery voltage reaches the first value (the initially set end-of-charge voltage) will not be near the minimum point of the voltage increase rate. Therefore, if it is determined that the second derivative is positive, the processor can determine that the time when the battery voltage reaches the first value is not near the minimum point of the battery voltage increase rate (S950).

[0128] Alternatively, if it is determined that the second-order differential value is not positive, the processor may calculate a third-order differential value of the battery voltage and determine whether the calculated third-order differential value is within a predetermined range (S940). For example, the processor may determine whether the third-order differential value is equal to or greater than a second predetermined value (e.g., a real number b, for example, −0.01). According to the voltage profile (e.g., the voltage profile of FIG. 8), if the second-order differential value is not positive (i.e., the current voltage increase rate is decreasing) and the third-order differential value is equal to or greater than the second predetermined value, this indicates that a minimum point in the voltage increase rate will soon arrive. Therefore, if it is determined that the third-order differential value is equal to or greater than the second predetermined value, the processor may determine that the time when the battery voltage value reaches the first value is predicted to be near a minimum point in the battery voltage increase rate (S960).

[0129] On the other hand, even if the second derivative is not positive (i.e., even if the current voltage increase rate is decreasing), if the third derivative is not equal to or greater than the second predetermined value, it means that the minimum point of the voltage increase rate will not arrive soon. Therefore, if it is determined that the third derivative is not equal to or greater than the second predetermined value, the processor may determine that the time when the battery voltage value reaches the first value is not predicted to be near the minimum point of the battery voltage increase rate (S950).

[0130] The processor can then maintain or change the end-of-charge voltage based on a determination of whether the time when the battery voltage value reaches the first value is predicted to be near a minimum point in the battery voltage increase rate.

[0131] For example, if it is determined that the time when the battery voltage value reaches the first value is not predicted to be near a minimum point in the battery voltage increase rate, the processor may maintain the end-of-charge voltage as the first value (S952).

[0132] Alternatively, if it is determined that the time when the battery voltage value reaches the first value is predicted to be near the minimum point of the battery voltage increase rate, the charge completion voltage can be adjusted upward to prevent the constant voltage charging time from becoming longer. For example, the processor can determine whether a second value obtained by adding a third predetermined value (e.g., a positive real number c, e.g., 0.05 V) to the first value is equal to or less than the upper operating voltage limit (S962). If it is determined that the second value obtained by adding the third predetermined value to the first value is equal to or less than the upper operating voltage limit, the processor can change the charge completion voltage to the second value (S964). Alternatively, if it is determined that the second value exceeds the upper operating voltage limit, the processor can change the charge completion voltage to the upper operating voltage limit (S966).

[0133] Thereafter, constant current charging or constant power charging can be performed until the battery voltage value reaches the charge completion voltage (which may be the first value, the second value, or the upper operating voltage limit, as the case may be). When the battery voltage value reaches the charge completion voltage, the constant current charging or constant power charging can be switched to constant voltage charging (S970). When constant voltage charging is performed, the battery voltage can be maintained at the charge completion voltage, and the current can be gradually reduced until it reaches the end current value, at which point charging can be completed.

[0134] 9 and the above description are merely examples, and the scope of the present disclosure is not limited thereto. According to other embodiments of the present disclosure, at least one step may be performed by a different configuration other than a processor, at least one step may be added / modified / omitted, or the order of at least one step may be changed.

[0135] Although the present invention has been described above using limited examples and drawings, it is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0136] 100 battery cells 110 cases 120 Cap Plate 130 terminals 140 Vent 150 Electrolyte inlet

Claims

1. determining a charge completion voltage of the constant current charge or constant power charge as a first value based on a target charge energy of the battery; During constant current charging or constant power charging, before the voltage value of the battery reaches the first value, determining whether the time when the voltage value of the battery reaches the first value is predicted to be near a minimum point of the voltage increase rate of the battery; maintaining or changing the charge completion voltage based on the determination result.

2. The step of determining whether the battery voltage increase rate is predicted to be near a minimum point includes: calculating at least one of a second-order differential value and a third-order differential value of the voltage of the battery based on the determination that the voltage value of the battery reaches a value obtained by subtracting a first predetermined value from the first value during the constant current charging or the constant power charging; and determining whether a time point at which the voltage value of the battery reaches the first value is predicted to be near a minimum point of a voltage increase rate of the battery, based on at least one of the second-order differential value and the third-order differential value.

3. The step of determining whether the battery voltage increase rate is predicted to be near a minimum point includes: calculating a second derivative of the voltage of the battery based on a determination that the voltage of the battery reaches a value obtained by subtracting a first predetermined value from the first value during the constant current charging or the constant power charging; The charge control method according to claim 1 , further comprising the step of determining whether the second derivative value is positive.

4. The step of determining whether the battery voltage increase rate is predicted to be near a minimum point includes:

4. The charge control method according to claim 3, further comprising the step of determining, based on determining that the second derivative value is positive, that the time point at which the voltage value of the battery reaches the first value is not predicted to be near a local minimum point of a voltage increase rate of the battery.

5. The step of determining whether the battery voltage increase rate is predicted to be near a minimum point includes: calculating a third derivative of the voltage of the battery based on determining that the second derivative is not positive; The charge control method according to claim 3 , further comprising the step of determining whether the third derivative value is within a predetermined range.

6. 6. The charge control method according to claim 5, wherein the step of determining whether the third-order differential value is within a predetermined range includes the step of determining whether the third-order differential value is equal to or greater than a second predetermined value.

7. 6. The charging control method according to claim 5, wherein the step of determining whether the time point at which the battery voltage value reaches the first value is predicted to be near a local minimum of a voltage increase rate of the battery further comprises the step of determining that the time point at which the battery voltage value reaches the first value is not predicted to be near a local minimum of a voltage increase rate of the battery, based on determining that the third derivative is not within the predetermined range.

8. 6. The charging control method according to claim 5, wherein the step of determining whether the time point at which the battery voltage value will reach the first value is predicted to be near a local minimum of a voltage increase rate of the battery further comprises the step of determining that the time point at which the battery voltage value will reach the first value is predicted to be near a local minimum of a voltage increase rate of the battery, based on determining that the third derivative is within the predetermined range.

9. 2. The charging control method according to claim 1, wherein the step of maintaining or changing the charge completion voltage includes a step of maintaining the charge completion voltage at the first value based on determining that the time point at which the voltage value of the battery reaches the first value is not predicted to be near a minimum point of a voltage increase rate of the battery.

10. 2. The charging control method according to claim 1, wherein the step of maintaining or changing the charge completion voltage includes a step of changing the charge completion voltage to a second value based on determining that the time when the voltage value of the battery reaches the first value is predicted to be near a minimum point of a voltage increase rate of the battery.

11. when a value obtained by adding a third predetermined value to the first value is equal to or lower than an upper operating voltage limit of the battery, the second value is a value obtained by adding the third predetermined value to the first value; 11. The charge control method according to claim 10, wherein when a value obtained by adding the third predetermined value to the first value exceeds an upper operating voltage limit of the battery, the second value is the upper operating voltage limit.

12. the second derivative value includes a value obtained by differentiating the voltage of the battery twice with respect to the charge amount or time, 3. The charge control method according to claim 2, wherein the third derivative value includes a value obtained by differentiating the voltage of the battery three times with respect to the charge amount or time.

13. The charge control method according to claim 1 , further comprising the step of switching to constant voltage charging based on determining that the voltage value of the battery reaches the charge completion voltage.

14. a memory for storing one or more instructions; Executing the one or more stored instructions Determine a charge completion voltage of the constant current charge or constant power charge as a first value based on a target charge energy of the battery; During constant current charging or constant power charging, before the voltage value of the battery reaches the first value, it is determined whether the time point at which the voltage value of the battery reaches the first value is predicted to be near a minimum point of the voltage increase rate of the battery; a processor configured to maintain or change the end-of-charge voltage based on the determination result.

15. The processor: calculating at least one of a second-order differential value or a third-order differential value of the voltage of the battery based on the determination that the voltage value of the battery reaches a value obtained by subtracting a first predetermined value from the first value during the constant current charging or the constant power charging; 15. The charge control device according to claim 14, further configured to determine whether a time point at which the voltage value of the battery reaches the first value is predicted to be near a minimum point of a voltage increase rate of the battery, based on at least one of the second-order differential value or the third-order differential value.

16. The processor: calculating a second derivative value of the voltage of the battery based on the determination that the voltage value of the battery reaches a value obtained by subtracting a first predetermined value from the first value during the constant current charging or the constant power charging; The charge control device according to claim 14 , further configured to determine whether the second derivative value is positive.

17. 17. The charge control device according to claim 16, wherein the processor is further configured to determine, based on determining that the second derivative value is positive, that a time point at which the voltage value of the battery reaches the first value is not predicted to be near a local minimum point of a voltage increase rate of the battery.

18. The processor: calculating a third derivative of the voltage of the battery based on the determination that the second derivative is not positive; The charge control device according to claim 16, further configured to determine whether the third derivative value is within a predetermined range.

19. 19. The charge control device according to claim 18, wherein the processor is further configured to determine, based on determining that the third derivative value is not within the predetermined range, that a time point at which the voltage value of the battery reaches the first value is not predicted to be near a local minimum point of a voltage increase rate of the battery.

20. 19. The charge control device according to claim 18, wherein the processor is further configured to determine, based on determining that the third derivative value is within the predetermined range, that a time point at which the voltage value of the battery reaches the first value is predicted to be near a minimum point of a voltage increase rate of the battery.

Images