Battery cell charge control system and method

Abstract

To provide a battery cell charging control system and method for performing charging by reducing a charging current on the basis of a charging part reaction time required for a current value change of the charging current.SOLUTION: A battery cell charging control system and method are disclosed. And a charging control unit configured to control the charging unit to charge the battery cell by reducing the charging current when a voltage of the battery cell reaches a full charge voltage, determine a current reduction width based on a charging unit reaction time taken to change a current value of the charging current, and control the charging unit to charge the battery cell by reducing the charging current by the determined current reduction width.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery cell charge control system and method, and more particularly to a battery cell charge control system and method for charging by reducing the charge current based on the charging unit reaction time required for a change in the current value of the charge current. [Background technology]

[0002] An energy storage system (ESS) is a system that stores large amounts of electrical energy and supplies the stored energy when it is needed, thereby improving energy efficiency. An ESS may include a battery system, a battery management system (BMS) that manages the battery system by monitoring the battery system's voltage, current, temperature, etc., a power conversion system (PCS) that performs alternating current (AC)-direct current (DC) conversion and distribution functions, and an energy management system (EMS) that controls the energy flow of the ESS and collects and manages information on the ESS's status, etc., to provide integrated control of the entire ESS system.

[0003] Typically, an ESS battery system includes multiple battery racks electrically connected to each other, and each battery rack may contain dozens, or even hundreds, of series-connected cells. When each cell voltage is fully charged at its operating voltage, if charging continues at the original charging current, it may exceed the operating voltage and result in overcharging. To prevent overcharging, the PCS limits the voltage by reducing the current to a lower level. In this case, if the current reduction amount is large, the charging time becomes longer. Conversely, if the current reduction amount is small, overcharging may occur unless the current is controlled quickly.

[0004] The information disclosed above in this Background of the Invention section is merely intended to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a battery cell charging control system and method that reduces the charging current based on the charging unit reaction time required for a change in the current value of the charging current to solve the above problems.

[0006] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0007] A battery cell charge control system according to an embodiment of the present invention may include a charging unit that generates a charging current using an external power supply supplied to the battery cell and transmits the charging current to the battery cell; and a charging control unit that reduces the charging current when the voltage of the battery cell reaches a full charge voltage, controls the charging unit to charge the battery cell, determines a current reduction amount based on a charging unit reaction time required for a current value change of the charging current, reduces the charging current by the determined current reduction amount, and controls the charging unit to charge the battery cell.

[0008] In one embodiment, the charging control unit may record the point in time at which the charging current starts to decrease as the voltage of the battery cell reaches the full charge voltage as the current guide start point.

[0009] In one embodiment, the charging control unit may set the first current decrease width and the first charging unit reaction time to initial settings.

[0010] In one embodiment, the charge control unit may transmit a first guide current value, which is reduced from the current value of the charging current by a first current reduction width, to the charging unit.

[0011] In one embodiment, the charging control unit can measure a second charging unit reaction time, which is the time it takes for the charging current to change from a current value of the charging current to a first guide current value, from the start of current guidance in the charging unit.

[0012] In one embodiment, the charge control unit may calculate the second current decrease width based on the second charging unit reaction time.

[0013] In one embodiment, the second current decrease amount is W d1 , the second current decrease width is W d2 , the first live part reaction time is T r1 , the second live part reaction time is T r2 In this case, it can be calculated using the following formula 1.

[0014]

number

[0015] In one embodiment, the charging control unit may transmit a second guide current value, which is reduced from the first guide current value by a second current reduction width, to the charging unit.

[0016] In one embodiment, the charge control unit may reduce the charging current to the second guide current value and control the charging unit to charge the battery cell.

[0017] A battery cell charging control method according to an embodiment of the present invention may include a charging step of generating a charging current using an external power supply supplied to the battery cell through a charging unit and transmitting the charging current to the battery cell; and a charging control step of reducing the charging current when a voltage of the battery cell reaches a full charge voltage through a charging control unit, controlling the charging unit to charge the battery cell, determining a current reduction amount based on a charging unit reaction time required for a current value change of the charging current, reducing the charging current by the determined current reduction amount, and controlling the charging unit to charge the battery cell.

[0018] In one embodiment, the charge control step may include recording a time point at which the charging current starts to decrease as the voltage of the battery cell reaches a full charge voltage as a current guide start time point.

[0019] In one embodiment, the charging control step may further include setting the first current decrease width and the first charging unit reaction time to initial settings.

[0020] In an embodiment, the step of controlling charging may further include the step of transmitting a first guide current value, which is reduced from the current value of the charging current by a first current reduction width, to the charging unit.

[0021] In one embodiment, the charging control step may further include a step of measuring, in the charging unit, a reaction time taken for the charging current to change from a current value of the charging current to a first guide current value from a current guide start point.

[0022] In one embodiment, the charging control step may further include calculating a second current decrease width based on a second charging unit reaction time.

[0023] In one embodiment, the step of calculating the second current decrease amount comprises: d1 , the second current decrease width is W d2 , the first live part reaction time is T r1 , the second live part reaction time is T r2In this case, the method may include a step of calculating the second current decrease width by the following formula 1.

[0024]

number

[0025] In an embodiment, the charging control step may further include transmitting a second guide current value, which is reduced from the first guide current value by a second current reduction width, to the charging unit.

[0026] In one embodiment, the charging control step may further include the step of reducing the charging current to the second guide current value and controlling the charging unit to charge the battery cell. [Effects of the Invention]

[0027] According to one embodiment of the present invention, the charging unit reaction time required for a change in the current value of the charging current is sensed, and the charging current is reduced based on that time, thereby shortening the charging time and preventing overcharging.

[0028] According to one embodiment of the present invention, instead of reducing the charging current by a fixed amount at the time of full charge, the amount of current reduction is varied by detecting the time it takes for the actual current reduction of the charging unit, thereby enabling charging in a shorter time than conventional methods and preventing overcharging.

[0029] However, the effects that can be obtained by the present invention are not limited to the effects described above, and other technical effects not mentioned will 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 attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited solely to the matters depicted in these drawings. [Figure 1] Figure 1 is a graph showing the change in current and voltage over time during conventional CV charging. [Figure 2] Figure 2 is a graph showing the change in current and voltage over time when simulating CV charging with a conventional ESS. [Figure 3] FIG. 3 is a schematic diagram of a battery cell charging control system according to one embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing a simulation result as an example of a reduction in charging time by a battery cell charge control system according to an embodiment of the present invention. [Figure 5] FIG. 5 is a flowchart illustrating a battery cell charging control method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts consistent with the technical ideas of the present invention, in accordance with the principle that the 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 only some of the most preferred embodiments of the present invention and do not represent the entire technical ideas of the present invention, and that various equivalents and modifications that can be substituted for them may exist at the time of filing this application.

[0032] Also, as used in this specification, "comprise" and / or "comprising" specify the presence of stated shapes, numbers, steps, operations, members, elements, and / or groups thereof, but do not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements, and / or groups thereof.

[0033] Furthermore, for the purpose of understanding 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 may be 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, "substantially identical" can include deviations that are considered low in the art, for example, deviations within 5%. Furthermore, "uniformity of a parameter in a given region" can mean uniformity from an average perspective.

[0035] Although terms such as "first," "second," etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and it goes without saying that a first component may also be a second component unless otherwise specified.

[0036] Throughout the specification, unless otherwise specified, each element may be singular or plural.

[0037] When an arbitrary structure is disposed "on (or below)" a component or "above (or below)" a component, it can mean not only that the arbitrary structure is disposed in contact with the upper surface (or lower surface) of the component, but also that another structure may be interposed between the component and the arbitrary structure disposed above (or below) the component.

[0038] Furthermore, when a component is described as being "on," "connected to," or "coupled to" another component, it should be understood that the components may be directly coupled or coupled 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.

[0039] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Also, when describing embodiments of the present invention, the use of "may" refers to "one or more embodiments of the present invention." Phrases such as "one or more" preceding a list of elements modify the list of elements as a whole, and not the individual elements of the list.

[0040] Throughout the specification, when "A and / or B" is used, this means A, or B, or A and B, unless otherwise specified, and when "C to D" is used, this means at least C and at most D, unless otherwise specified.

[0041] When syntax such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group A, B, and C," or "at least one selected from among A, B, and C" is used to specify a list of elements A, B, and C, the syntax can refer to any and all suitable combinations.

[0042] The term "use" is considered synonymous with the term "utilize." As used herein, "substantially," "about," and similar terms are used as terms of approximation, not terms of degree, and are intended to account for inherent variations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art.

[0043] In this specification, terms such as "first," "second," and "third" are used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, drawing layer, or cross section from another element, component, region, drawing layer, or cross section. Thus, a first element, component, region, level, or section discussed below may be termed a second element, component, region, level, or section without departing from the teachings of the exemplary embodiments.

[0044] As shown, in describing the relationship of one element or feature to another, for ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," etc. are used throughout the specification. Spatially relative positions will be understood to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, the other elements would be understood as "beneath" or "below" and the illustrated element would be understood as "above" or "upper" of the other elements. Thus, the term "beneath" can encompass both an orientation of above and below.

[0045] The terminology used herein is for the purpose of describing embodiments of the present invention and is not intended to limit the present invention. The present invention will now be described in detail with reference to the accompanying drawings.

[0046] Figure 1 is a graph showing the change in current and voltage over time during conventional CV charging.

[0047] Referring to Figure 1, conventional lithium-ion batteries and lithium iron phosphate (Li-FePO4, LFP) batteries can only be charged by CV (Constant Voltage) charging, which allows the battery's full capacity to be used. CV charging, as shown in Figure 1, is a method of charging a battery while maintaining a constant voltage, and is based on the principle that lithium ions are naturally absorbed into the electrode material by a constant pressure, which has the advantage of allowing stable charging without straining the battery.

[0048] Figure 2 is a graph showing the change in current and voltage over time when simulating CV charging with a conventional ESS.

[0049] Referring to Figure 2, a power conversion system (PCS) linked to a conventional energy storage system (ESS) does not support CV charging as shown in Figure 1. Therefore, a battery management system (BMS) guides the PCS to the amount of current that can be charged, and performs charging in a manner that mimics CV charging.

[0050] Most PCSs control current according to the BMS current guide and, since they do not support CV mode, perform full charging according to this current guide. When the cell voltage is fully charged at the operating voltage, continuing to charge at the original charging current may exceed the operating voltage and lead to overcharging. To prevent overcharging, the PCS reduces the current to a lower level to limit the voltage. In this case, if the current reduction amount is large, the charging time will be longer, and conversely, if the current reduction amount is small, there is a problem that overcharging may occur unless the current is controlled quickly.

[0051] The amount of current reduction in the charging current may vary depending on the time it takes from the time the BMS calculates the current guide value to the time it communicates with the Energy Management System (EMS) or PCS and the time it takes for the PCS to change the charging current value to the guided current value.

[0052] If the time required for the current value to change is short, the amount of current decrease can be reduced and the time required for full charge can be shortened, but if the time is long, the amount of current decrease must be increased to prevent overcharging even if the charging time is long.

[0053] However, since the time it takes for the current value to change varies depending on the type of PCS and the communication configuration, making it difficult to predict, conventional BMSs reduce the charging current by a fixed amount, increasing the current reduction amount to prevent the risk of overcharging, thereby giving the PCS sufficient time to operate.

[0054] However, when the charging current is reduced by a fixed amount by increasing the current reduction amount in this way, the charging time is disadvantageously long, although the PCS can change the current output more quickly.

[0055] FIG. 3 is a schematic diagram of a battery cell charging control system according to one embodiment of the present invention.

[0056] Referring to FIG. 3, a battery cell charge control system 100 according to one embodiment of the present invention is connected to tens to hundreds of battery cells 11 of a battery system 10 included in an energy storage system (ESS) and controls the charging of each battery cell.

[0057] The battery cell 11, which is the target of charge control by the battery cell charge control system 100 according to one embodiment of the present invention, is a chargeable and dischargeable battery cell in which an electrode assembly having a positive electrode / separator / negative electrode structure is impregnated with a lithium electrolyte and sealed inside a battery case. Such electrode assemblies are generally of a jelly roll structure (wound type) in which long sheet-type positive and negative electrodes, each coated with an active material on both sides, are rolled up with a separator interposed therebetween, or a stacked structure in which a number of positive and negative electrodes of a predetermined size, each coated with an active material on both sides, are stacked one on top of the other with a separator interposed therebetween.

[0058] The battery cell 11 can be either a cylindrical or rectangular battery cell in which an electrode assembly is built into a metal can battery case, or a pouch-type battery cell in which an electrode assembly is built into an aluminum laminate sheet battery case, depending on the battery shape.

[0059] The charger 20 is connected to an external power source and serves to supply power to the charging unit 110 .

[0060] The charging unit 110 is connected to the charger 20, generates a charging current using an external power source supplied to the battery cell 11, and transmits the charging current to the battery cell 11. In one embodiment, the charging unit 110 may be a PCS. The PCS is a system that converts electrical characteristics to store or release power in a battery, and performs alternating current (AC)-direct current (DC) conversion and power distribution functions. In the battery cell charging control system 100 according to one embodiment of the present invention, the PCS is the charging unit 110, and may serve to charge the battery cell 11 by reducing the charging current according to a current reduction amount determined by a charging control unit 120 (described later).

[0061] When the voltage of the battery cell 11 reaches the full charge voltage, the charge control unit 120 reduces the charging current and controls the charging unit 110 to charge the battery cell 11. The charge control unit 120 determines a current reduction amount based on a charging unit reaction time required for a change in the charging current value, reduces the charging current by the determined current reduction amount, and controls the charging unit 110 to charge the battery cell 11. In one embodiment, the charge control unit 120 may be a BMS. The BMS manages the battery system 10 by monitoring the voltage, current, temperature, etc. of the battery system 10, and may monitor the state of charge (SOC), state of health (SOH), etc. In addition, the BMS may perform control functions (e.g., temperature control, cell balancing control, charge / discharge control, etc.) and protection functions (e.g., over-discharge, over-charge, over-current prevention, etc.) based on the state monitoring results. In the battery cell charging control system 100 according to one embodiment of the present invention, the BMS is a charging control unit 120 that determines a current reduction amount, reduces the charging current by the determined current reduction amount, and controls the charging unit 110 to charge the battery cell 11.

[0062] In one embodiment, the charging control unit 120 records the point at which the charging current starts to decrease as the voltage of the battery cell 11 reaches the full charge voltage as the current guidance start point. Then, the charging control unit 120 sets the first current decrease amount and the first charging unit reaction time to initial values. Generally, a BMS may have a basic current decrease amount and a basic PCS reaction time for current amount guidance. In one embodiment, the first current decrease amount may be the basic current decrease amount of the BMS, and the first charging unit reaction time may be the basic PCS reaction time of the BMS. For example, the first current decrease amount may be set to 12.5%, and the first charging unit reaction time may be set to 90 seconds.

[0063] Then, the charging control unit 120 transmits a first guide current value, which is obtained by subtracting the first current reduction amount from the current value of the charging current, to the charging unit 110. For example, if the full charge voltage of the battery cell 11 is 4.15V and the current value when the full charge voltage is reached is 40A, the first guide current value is calculated by subtracting about 12.5% ​​from the current value by the first current reduction amount. That is, the first guide current value is calculated as 35 = 40 - (40 * 0.125), resulting in 35A. The first guide current value calculated in this way can be transmitted to the charging unit 110 via communication.

[0064] Thereafter, charging control unit 120 measures the second charging unit reaction time, which is the time it takes for the charging current value to change from the current value of 40 A to the first guide current value from the start of current guidance in charging unit 110. For example, it measures the time it takes for the current value to change from 40 A to the first guide current value of 35 A from the start of current guidance.

[0065] In this case, the charging control unit 120 may calculate the second current decrease amount based on the second charging unit reaction time. In one embodiment, the second current decrease amount is calculated when the first current decrease amount is W d1 , the second current decrease width is W d2 , the first live part reaction time is T r1 , the second live part reaction time is T r2 In this case, it can be calculated using the following formula 1.

[0066]

number

[0067] For example, the time it takes for the current to change from 40A to 35A, i.e., the second live part reaction time T r2 is 45 seconds, the second current reduction is calculated as 6.25% by the formula 6.25% = 12.5% ​​- (12.5% / 90) * (90 - 45).

[0068] Once the second current decrease amount is calculated, the charging control unit 120 transmits the second guide current value, which is obtained by decreasing the first guide current value by the second current decrease amount, to the charging unit 110. For example, when the full charge voltage reaches 4.15V again, the second guide current value is calculated by decreasing the current first guide current value of 35A by the second current decrease amount of 6.25%, i.e., 32.8125=35-(35*0.0625), to obtain 32.8125A. The calculated second guide current value can be transmitted to the charging unit 110 via communication.

[0069] Then, the charging control unit 120 reduces the charging current to the second guide current value and controls the charging unit 110 to charge the battery cell 11. For example, the charging control unit 120 can reduce the charging current to the second guide current value of 32.8125 A calculated as above and controls the charging unit 110 to charge the battery cell 11.

[0070] According to one embodiment of the present invention, the charging unit reaction time required for a change in the current value of the charging current is sensed, and the charging current is reduced based on that time, thereby shortening the charging time and preventing overcharging.

[0071] According to one embodiment of the present invention, instead of reducing the charging current by a fixed amount at the time of full charge, the amount of current reduction is varied by detecting the time it takes for the actual current reduction of the charging unit 110, thereby enabling charging in a shorter time than conventional methods and preventing overcharging.

[0072] FIG. 4 is a diagram showing a simulation result as an example of a reduction in charging time by a battery cell charge control system according to an embodiment of the present invention.

[0073] 4, when the basic current decrease amount, i.e., the first current decrease amount, is set to 50% and the basic PCS response time, i.e., the first charging unit response time, is set to 90 seconds as the initial setting, and the time it takes for the current to change from 30 A to 15 A according to the first current decrease amount is measured to be 22.5 seconds, by substituting each value into Equation 1 described above, 12.25% can be calculated as 12.25% = 50% - (50% / 90) * (90 - 22.5). As a result, when charging is performed according to the first charging unit response time and the first current decrease amount as in the related art, the full charge time is about 2427 seconds, whereas when charging is performed according to the second charging unit response time and the second current decrease amount according to the battery cell charge control system 100 according to an embodiment of the present invention, the full charge time is about 1790 seconds, which confirms that the charging time is significantly reduced.

[0074] FIG. 5 is a flowchart illustrating a battery cell charging control method according to an embodiment of the present invention.

[0075] As shown in FIG. 5, the battery cell charging control method according to an embodiment of the present invention may include steps S210 to S220.

[0076] Step S210 is a charging step in which a charging current is generated using an external power source supplied to the battery cell through the charging unit, and the charging current is transmitted to the battery cell.

[0077] Step S220 is a charge control step in which, when the voltage of the battery cell reaches the full charge voltage through the charge control unit, the charge current is reduced and the charge unit is controlled to charge the battery cell, the current reduction amount is determined based on the charge unit reaction time required for the current value change of the charge current, the charge current is reduced by the determined current reduction amount, and the charge unit is controlled to charge the battery cell.

[0078] In one embodiment, step S220 may include recording the point at which the charging current starts to decrease as the voltage of the battery cell reaches the full charge voltage as a current guide start point.

[0079] In one embodiment, step S220 may further include setting the first current decrease width and the first charging unit reaction time to initial values.

[0080] In an embodiment, step S220 may further include transmitting a first guide current value, which is reduced from the current value of the charging current by a first current reduction width, to the charging unit.

[0081] In one embodiment, step S220 may further include measuring, in the charging unit, a second charging unit reaction time required for the charging current to change from the current value of the charging current to the first guide current value from the start of current guidance.

[0082] In one embodiment, step S220 may further include calculating a second current decrease width based on the second charging unit reaction time.

[0083] In an embodiment, step S220 may further include transmitting a second guide current value, which is reduced from the first guide current value by a second current reduction width, to the charging unit.

[0084] In one embodiment, step S220 may further include the step of reducing the charging current to the second guide current value and controlling the charging unit to charge the battery cell.

[0085] The battery cell charging control method according to one embodiment of the present invention has been described with reference to the flowcharts shown in the drawings. For ease of explanation, the method has been illustrated and described as a series of blocks. However, the present invention is not limited to the sequence of the blocks. Some blocks may occur in a different sequence or simultaneously with other blocks than those illustrated and described herein. Various other branches, flow paths, and sequence of blocks may be implemented to achieve the same or similar results. Also, not all of the illustrated blocks may be required to implement the method described herein.

[0086] Meanwhile, in the description with reference to FIG. 5, each step may be further divided into additional steps or combined into fewer steps depending on the implementation of the present invention. Also, some steps may be omitted as necessary, and the sequence between steps may be changed. Also, even if other content is omitted, the content of FIGS. 1 to 4 can be applied to the content of FIG. 5. Also, the content of FIG. 5 can be applied to the content of FIGS. 1 to 4.

[0087] Although the present invention has been described above using limited examples and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0088] 10: Battery system 11: Battery cell 20: Charger 100: Battery cell charge control system 110:Charging part 120: Charging control unit

Claims

1. a charging unit that generates a charging current using an external power supply supplied to the battery cell and transfers the charging current to the battery cell; a charging control unit that reduces the charging current when the voltage of the battery cell reaches a full charge voltage, and controls the charging unit to charge the battery cell; determines a current reduction amount based on a charging unit reaction time required for a current value change of the charging current, reduces the charging current by the determined current reduction amount, and controls the charging unit to charge the battery cell.

2. The charging control unit 2. The battery cell charging control system according to claim 1, wherein a time point at which the charging current starts to decrease as the voltage of the battery cell reaches a full charge voltage is recorded as a current guide start time point.

3. The charging control unit 3. The battery cell charging control system according to claim 2, wherein the first current decrease width and the first charging unit reaction time are set to initial values.

4. The charging control unit 4. The battery cell charging control system according to claim 3, wherein a first guide current value, which is reduced from the current value of the charging current by a first current reduction width, is transmitted to the charging unit.

5. The charging control unit 5. The battery cell charging control system of claim 4, wherein the charging unit measures a second charging unit reaction time required for the charging current to change from the current value to the first guide current value from the current guide start point.

6. The charging control unit The battery cell charging control system according to claim 5, wherein the second current decrease width is calculated based on the second charging unit reaction time.

7. The second current decrease width is The first current decrease width is W d1 , the second current decrease width is W d2 , the first charging section reaction time is T r1 , the second charging section reaction time is T r2 The battery cell charging control system according to claim 6, wherein the battery cell charging time is calculated by the following equation 1: [Equation 1]

8. The charging control unit 7. The battery cell charging control system according to claim 6, wherein a second guide current value, which is reduced from the first guide current value by the second current reduction width, is transmitted to the charging unit.

9. The charging control unit 9. The battery cell charging control system according to claim 8, wherein the charging unit controls the charging of the battery cell by reducing the charging current to the second guide current value.

10. a charging step of generating a charging current using an external power source supplied to the battery cell through a charging unit and transmitting the charging current to the battery cell; a charge control step of controlling, through a charge control unit, when a voltage of the battery cell reaches a full charge voltage, to reduce the charging current and cause the charging unit to charge the battery cell; determining a current reduction amount based on a charging unit reaction time required for a current value change of the charging current, reducing the charging current by the determined current reduction amount, and causing the charging unit to charge the battery cell.

11. The charge control step includes:

11. The method of claim 10, further comprising recording a time point at which the charging current starts to decrease as the voltage of the battery cell reaches a full charge voltage as a current guide start time point.

12. The charge control step includes:

12. The method of claim 11, further comprising the step of setting the first current decrease width and the first charging unit reaction time to initial settings.

13. The charge control step includes:

13. The method of claim 12, further comprising transmitting a first guide current value, which is reduced from the current value of the charging current by a first current reduction width, to the charging unit.

14. The charge control step includes:

14. The method of claim 13, further comprising measuring, in the charging unit, a second charging unit reaction time required for the charging current to change from a current value to the first guide current value from a current guide start point.

15. The charge control step includes: The method of claim 14, further comprising calculating a second current decrease width based on a reaction time of the second charging unit.

16. The step of calculating the second current decrease width includes: The first current decrease width is W d1 , the second current decrease width is W d2 , the first charging section reaction time is T r1 , the second charging section reaction time is T r2 12. The method of claim 11, further comprising calculating the second current decrease width according to the following equation (1): [Equation 2]

17. The charge control step includes:

16. The method of claim 15, further comprising transmitting a second guide current value, which is reduced from the first guide current value by the second current reduction width, to the charging unit.

18. The charge control step includes:

18. The method of claim 17, further comprising the step of reducing the charging current to the second guide current value and controlling the charging unit to charge the battery cell.

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