Method for balancing energy storage device

Abstract

A method for controlling a secondary battery according to an embodiment of the present invention comprises the steps of: providing a module including one or more cells; calculating per-cell life expectancy information for the one or more cells included in the generated module; setting a target voltage on the basis of the calculated per-cell life expectancy information; and, on the basis of the set target voltage, using different voltages for the one or more cells included in the module.

Description

Balancing method for energy storage devices

[0001] Embodiments of the present invention are directly or indirectly related to secondary batteries. More specifically, for example, they can be applied to various devices such as energy storage devices capable of extending lifespan.

[0002] Unlike primary batteries, which are used once and then discarded, secondary batteries refer to batteries that can be recharged and used repeatedly. They are also called rechargeable batteries, and representative types include lithium-ion batteries (Li-icon), lithium-polymer batteries (Li-Po), lead-acid batteries (Lead-acid), nickel-cadmium batteries (Ni-Cd), and nickel-hydrogen batteries (Ni-MH).

[0003] Secondary batteries are utilized in various industries, including electric vehicles, smartphones, laptops, tablet PCs, energy storage devices, drones, and medical devices.

[0004] Meanwhile, major factors determining the lifespan of a secondary battery include chemical factors (e.g., degradation of cathode and anode materials, electrolyte decomposition and depletion, etc.), physical factors (e.g., reduced contact between electrodes and current collectors, electrode cracking and delamination, etc.), and operating conditions (e.g., charge / discharge rate, temperature, humidity, etc.).

[0005] Accordingly, as a measure to extend the lifespan of the secondary battery, the charge / discharge range is maintained at 20 to 80%, fast charging is minimized, or it is used and stored at an appropriate temperature (20 to 30 degrees Celsius).

[0006] However, unlike the aforementioned method that requires user intervention, there is a need for technology to automatically extend the lifespan of secondary batteries or energy storage devices containing multiple cells in a single module.

[0007] One embodiment of the present invention aims to provide a technology for automatically extending the lifespan of a secondary battery or energy storage device containing multiple cells in a single module by solving the problems of the aforementioned prior art.

[0008] A control method for a secondary battery according to an embodiment of the present invention for solving the aforementioned technical problem comprises the steps of: providing a module including at least one cell; calculating expected lifespan information for each of the at least one cell included in the module; setting a target voltage based on the calculated expected lifespan information for each cell; and using different voltages for each of the at least one cell included in the module based on the set target voltage.

[0009] Here, the target voltage setting means, for example, that when the value of the expected lifespan information of the first cell is greater than the value of the expected lifespan information of the second cell, the target voltage set in the second cell is set to be smaller than the target voltage set in the first cell, and when the value of the expected lifespan information of the first cell is smaller than the value of the expected lifespan information of the third cell, the target voltage set in the third cell is set to be larger than the target voltage set in the first cell.

[0010] A control method for an energy storage device according to an embodiment of the present invention comprises the steps of: providing a module including at least one cell; calculating expected lifespan information for each of the at least one cell included in the module when a preset condition is satisfied; setting a target voltage based on the calculated expected lifespan information for each cell; and using different voltages for each of the at least one cell included in the module based on the set target voltage.

[0011] The step of setting the target voltage further includes, when the value of the expected lifespan information of the first cell is greater than the value of the expected lifespan information of the second cell, setting the target voltage set in the second cell to be smaller than the target voltage set in the first cell, and when the value of the expected lifespan information of the first cell is smaller than the value of the expected lifespan information of the third cell, setting the target voltage set in the third cell to be larger than the target voltage set in the first cell.

[0012] Furthermore, a control method for an energy storage device according to an embodiment of the present invention further includes the step of comparing the sum of the voltage of the module and the target voltage set for each cell, and the step of readjusting the target voltage set for each cell if the comparison result is not the same.

[0013] In addition, a control method for an energy storage device according to an embodiment of the present invention further includes the step of determining whether there exists a target voltage exceeding a limit value among the target voltages set for each cell when the comparison result is the same, and the step of readjusting the target voltage set for each cell when there exists a target voltage when the determination result is the same.

[0014] Furthermore, the numerical value of the expected lifespan information of each cell and the target voltage set for each corresponding cell are characterized by a proportional relationship.

[0015] And, an energy lowering device according to one embodiment of the present invention comprises a module composed of at least one cell, and a controller that calculates expected lifespan information for at least one cell included in the module, and controls that different voltages are used for each of the at least one cell included in the module based on the calculated expected lifespan information.

[0016] The above controller is characterized by, for example, comparing the sum of the voltage of the module and the target voltage set in each cell, and if the comparison result is not the same, readjusting the target voltage set in each cell.

[0017] In addition, the controller is characterized by determining whether there is a target voltage exceeding a limit value among the target voltages set in each cell when the comparison result is the same, and if there is a target voltage exceeding a limit value as a result of the determination, readjusting the target voltage set in each cell.

[0018] According to one embodiment of the present invention, a technical effect is expected that can automatically extend the lifespan of a secondary battery or energy storage device containing a plurality of cells in a single module.

[0019] In addition, in addition to the effects of the invention explicitly described herein, technical effects that can be inferred by a person skilled in the art from the specification and drawings also fall within the other scope of the rights of the present invention.

[0020] FIG. 1 is a schematic perspective view illustrating a module of an energy storage device.

[0021] Figure 2 is a graph illustrating a case where the expected lifespan of a module is shortened according to the prior art.

[0022] FIG. 3 is a schematic diagram illustrating an apparatus according to an embodiment of the present invention.

[0023] FIG. 4 is a graph showing that the expected lifespan of a module is extended based on cell balancing according to an embodiment of the present invention illustrated in FIG. 3.

[0024] FIG. 5 is a flowchart illustrating a method for controlling a device according to an embodiment of the present invention.

[0025] And, FIG. 6 is a flowchart illustrating a method for controlling a device according to another embodiment of the present invention.

[0026] Throughout the specification, identical reference numbers denote substantially identical components. In the following description, detailed descriptions of components and functions known in the art may be omitted if they are not related to the core components of the invention. The meanings of the terms described in this specification should be understood as follows.

[0027] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0028] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the depicted details. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0029] Where terms such as 'comprising,' 'having,' 'consisting of,' etc. are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise.

[0030] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0031] In the case of describing a positional relationship, for example, when the positional relationship between two parts is described using expressions such as 'on,' 'upper,' 'lower,' or 'next to,' one or more other parts may be located between the two parts unless 'immediately' or 'directly' is used.

[0032] In the case of an explanation of a temporal relationship, for example, when a temporal sequence is explained using 'after', 'following', 'next', 'before', etc., it may include cases where the sequence is not continuous unless 'immediately' or 'directly' is used.

[0033] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of the present invention.

[0034] The term “at least one” should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of “at least one of the first item, the second item and the third item” may mean not only the first item, the second item or the third item individually, but also all combinations of items that can be presented from two or more of the first item, the second item and the third item.

[0035] The features of each of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each embodiment may be implemented independently of one another or may be implemented together in an associated relationship.

[0036] Hereinafter, embodiments of the present specification will be described in detail with reference to the attached drawings.

[0037] FIG. 1 is a schematic perspective view illustrating a module of an energy storage device.

[0038] Energy storage devices to which the present invention can be applied include, for example, secondary batteries and capacitors, but are not necessarily limited thereto, and the scope of rights should be interpreted as described in the claims.

[0039] Meanwhile, among capacitors, the ultra-capacitor (UC) is an energy storage device capable of compensating for the weaknesses of secondary batteries, such as short cycle times and instantaneous high voltage, due to its high efficiency and fast charge / discharge characteristics.

[0040] Therefore, ultracapacitors are used not only as auxiliary power sources for mobile devices such as mobile phones, tablet PCs, and laptops, but also as main or auxiliary power sources for electric vehicles, hybrid vehicles, solar power units, nighttime road lights, and uninterruptible power supplies (UPS) that require high capacity.

[0041] The module of the energy storage device illustrated in FIG. 1 includes, for example, a plurality of cells, a module case, and a module cover.

[0042] The cell includes a cylindrical element having an upper surface and a lower surface, wound along the circumferential direction with respect to a central axis. Specifically, the element includes a first electrode and a second electrode facing each other with a separator in between, and includes a cylindrical element formed by winding these.

[0043] Furthermore, the cells store energy, and multiple cells located within the module are electrically connected.

[0044] Also, the module case accommodates multiple cells, and the module cover is attached to the top and bottom of the module case.

[0045] Meanwhile, the module illustrated in FIG. 1 may include 48 cells, but the present invention is not necessarily limited thereto, and the scope of the patent rights should be determined according to the matters described in the claims.

[0046] Figure 2 is a graph illustrating a case where the expected lifespan of a module is shortened according to the prior art.

[0047] Number 210 shown in Fig. 2 represents, for example, a voltage (V) condition set for each cell (corresponding to number 10 shown in Fig. 1) included in a module (corresponding to number 1 shown in Fig. 1).

[0048] Meanwhile, number 220 shown in Figure 2 represents, for example, the expected lifespan (year) of each cell.

[0049] For reference, the number of cells included in a secondary battery module varies depending on the battery type and design method, but generally falls within the following ranges.

[0050] A small battery module may include, for example, about 4 to 12 cells. Furthermore, an electric vehicle (EV) battery module may include, for example, about 624 or 1,216 cells. And, a large ESS (energy storage device) module may include, for example, about 24 to 40 or more cells. Although FIG. 2 illustrates the presence of about 48 cells along the horizontal axis, the present invention is not necessarily limited thereto.

[0051] And, number 230 shown in Fig. 2 represents, for example, the expected lifespan (year) of the module.

[0052] As shown in FIG. 2, if balancing is performed by maintaining the same voltage (210) for all cells, the expected lifespan of the module is fixed at 5 years (230) based on the cell with the fastest deterioration (e.g., corresponding to cell 26 in FIG. 2). Meanwhile, the cell with the fastest deterioration refers to, for example, the cell with the lowest remaining lifespan, the cell with the fastest aging, etc.

[0053] On the other hand, in order to solve the problems of the aforementioned conventional technology, one embodiment of the present invention is designed to improve the cell management technology through life prediction so as to vary to a balancing level suitable for the current cell state.

[0054] For example, the lifespan of a module is determined based on the cell that ages the fastest among multiple cells connected in series. Furthermore, the lifespan of a cell is most significantly affected by factors such as operating voltage and temperature.

[0055] Therefore, based on the predicted remaining lifespan of the cells, the operating conditions of the cells are modified according to their expected lifespan. For example, cells with a short expected lifespan are used under better conditions (low voltage), while cells with a relatively long expected lifespan are subjected to slightly harsher operating conditions (high voltage) to the extent that it does not cause problems, thereby achieving the technical effect of extending the module's lifespan.

[0056] I will explain this in more detail below with reference to Figure 3, etc.

[0057] FIG. 3 is a schematic diagram illustrating an apparatus according to an embodiment of the present invention. The apparatus illustrated in FIG. 3 can be applied, for example, to secondary batteries and various energy storage devices.

[0058] A device according to one embodiment of the present invention includes, for example, a module (310) and a controller (320).

[0059] And, the module (310) is composed of at least one cell (311, 312, 313, 314, 315, 316, 317). Meanwhile, at least one cell (311, 312, 313, 314, 315, 316, 317) is connected in series, for example.

[0060] Meanwhile, the controller (320) calculates expected lifespan information for at least one cell (311, 312, 313, 314, 315, 316, 317) included in the module (310), and is designed to use different voltages for each of the at least one cell (311, 312, 313, 314, 315, 316, 317) included in the module (310) based on the calculated expected lifespan information.

[0061] In particular, according to one embodiment of the present invention, the numerical value of the expected lifespan information of each cell (311, 312, 313, 314, 315, 316, 317) and the target voltage set for each corresponding cell (311, 312, 313, 314, 315, 316, 317) are set to be in a proportional relationship. Here, the term "target voltage" refers to a different voltage set for use by each cell.

[0062] In other words, there is an advantage in extending the module's lifespan by using cells with a short expected lifespan under better conditions, and applying slightly harsher operating conditions to cells with a relatively long expected lifespan without causing issues.

[0063] Furthermore, for example, the calculation circuit (321) within the controller (320) is responsible for calculating the expected lifespan information of each cell and setting the target voltage.

[0064] The balancing circuit (322) within the controller (320) directly performs the balancing operation. For example, it is responsible for lowering the voltage of a specific cell by consuming energy using a resistor, or for moving energy from a high-voltage cell to a low-voltage cell.

[0065] And, the communication circuit (323) within the controller (320) can perform the role of transmitting information about the cell within the module (e.g., voltage, current, temperature, balancing status, expected lifespan, target voltage, etc.) via various communication methods (e.g., CAN (Controller Area Network), Ethernet, RS-485, etc.).

[0066] Meanwhile, the calculation circuit (321), balancing circuit (322), communication circuit (323), etc. within the controller (320) may be implemented, for example, in software, hardware, or a combination thereof.

[0067] Meanwhile, additionally, the controller (320) may compare the sum of each voltage of the module (310) and the target voltage set in each cell (311, 312, 313, 314, 315, 316, 317), and if the comparison result is not the same, readjust the target voltage set in each cell.

[0068] And, the controller (320) determines whether there is a target voltage that exceeds a limit value among the target voltages set in each cell (311, 312, 313, 314, 315, 316, 317) when the comparison result is the same. And, if there is a target voltage that exceeds a limit value when the determination result is the same, the controller is characterized by readjusting the target voltage set in each cell (311, 312, 313, 314, 315, 316, 317).

[0069] FIG. 4 is a graph showing that the expected lifespan of a module is extended based on cell balancing according to an embodiment of the present invention illustrated in FIG. 3.

[0070] Number 310 shown in Fig. 4 represents, for example, a voltage (V) condition set for each cell (corresponding to number 10 shown in Fig. 1) included in a module (corresponding to number 1 shown in Fig. 1).

[0071] Meanwhile, number 320 shown in Fig. 4 represents, for example, the expected lifespan (year) of each cell.

[0072] And, number 330 shown in Fig. 4 represents, for example, the expected lifespan (year) of the module.

[0073] As shown in FIG. 4, by balancing each cell at a different voltage according to the cell-specific state (e.g., expected lifespan information), the expected lifespan of each cell is equalized, and it can be confirmed that the expected lifespan of the module is improved to 8 years. Compared to the conventional technology shown in FIG. 2, there is a technical effect of increasing the expected lifespan of the module by about 3 years under the same conditions.

[0074] FIG. 5 is a flowchart illustrating a method for controlling a device according to an embodiment of the present invention.

[0075] An energy storage device according to one embodiment of the present invention charges at least one cell included in a module (S510).

[0076] Furthermore, the energy storage device calculates expected lifespan information for at least one cell included in the module (S520).

[0077] For example, energy storage devices can measure capacity and internal resistance based on high-speed voltage and current data, and measure the expected lifespan of each cell through various lifespan prediction algorithms.

[0078] Furthermore, by utilizing hierarchical computational optimization techniques, it is possible to continuously improve data reliability and estimate life expectancy more precisely.

[0079] Additionally, the energy storage device is designed so that different voltages are used for at least one cell included in the module based on the expected lifespan information calculated in step S520 (S530).

[0080] Meanwhile, the embodiment illustrated in FIG. 5 can be similarly applied to a method for extending the lifespan of a secondary battery.

[0081] For example, a secondary battery produces a module composed of at least one cell (the at least one cell is connected in series, for example).

[0082] The secondary battery calculates expected lifespan information for each cell of at least one cell included in the generated module when preset conditions are satisfied. Here, the preset conditions may be a specific current, a specific voltage, or an arbitrary period.

[0083] In addition, the secondary battery is designed so that different voltages are applied to at least one cell included in the generated module, based on the calculated expected lifespan information for each cell.

[0084] For example, if the value of the expected lifespan information of the first cell (311 shown in FIG. 3) is greater than the value of the expected lifespan information of the second cell (312 shown in FIG. 3), the voltage set in the second cell (312 shown in FIG. 3) is set to be smaller than the voltage set in the first cell (311 shown in FIG. 3).

[0085] On the other hand, if the value of the expected lifespan information of the first cell (311 shown in FIG. 3) is smaller than the value of the expected lifespan information of the third cell (313 shown in FIG. 3), the voltage set in the third cell (313 shown in FIG. 3) is set to be greater than the voltage set in the first cell (311 shown in FIG. 3).

[0086] Also, FIG. 6 is a flowchart illustrating a control method of a device according to another embodiment of the present invention. The control method illustrated in FIG. 6 is applicable to secondary batteries, energy storage devices, etc., and combining it with the flowchart of FIG. 5, or deleting, adding, or changing some steps may also fall within another scope of the present invention.

[0087] A device according to another embodiment of the present invention calculates the expected lifespan of at least one cell included in the module (S610).

[0088] The device according to another embodiment of the present invention sets a target voltage for each cell based on the expected lifespan calculated in step S610 (S620).

[0089] A device according to another embodiment of the present invention compares the voltage of the module with the sum of the target voltages set in each cell (S630).

[0090] If the comparison result (S630) above is not the same, return to step S620 to readjust the target voltage set for each cell. The reason such a process is necessary is that if the sum of the target voltages per cell is not the same as the module voltage, balancing does not operate as intended, so a step to check whether the sum of the target voltages per cell is the same as the module voltage is required.

[0091] If the above comparison result (S630) is the same, it is determined whether there is a target voltage that exceeds the limit value among the target voltages set in each cell (S640). Here, the limit value means, for example, the maximum allowable voltage value.

[0092] Cells with a relatively short expected lifespan are set to a low target voltage, in which case some of the remaining cells must be used at a voltage higher than the average. Therefore, a step is required to ensure that no cell exceeds its rated voltage even when set to such a higher-than-average operating voltage.

[0093] If the above judgment result (S640) exists, return to step S620 to readjust the target voltage set for each cell.

[0094] If the above determination result (S640) does not exist, cell balancing is performed (S650), and it is determined whether the module voltage has changed (S660).

[0095] If the above judgment result (S660) is changed, it is designed to return to step S610. The reason for this design is that if the module voltage changes, the target voltage for each cell must also be re-determined.

[0096] Those skilled in the art to which the present invention pertains will understand that the above-described invention may be implemented in other specific forms without altering its technical concept or essential features.

[0097] Additionally, the methods described herein may be implemented at least partially using one or more computer programs or components. These components may be provided as a series of computer instructions via a computer-readable or machine-readable medium including volatile and non-volatile memory. The instructions may be provided as software or firmware and may be implemented wholly or partially in hardware configurations such as ASICs, FPGAs, DSPs, or other similar devices. The instructions may be configured to be executed by one or more processors or other hardware configurations, which perform or are capable of performing all or part of the methods and procedures disclosed herein when executing the series of computer instructions.

[0098] Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention.

[0099] Various embodiments for implementing the present invention have been described in detail in the previous section.

[0100] Since the present invention is applicable to secondary batteries and various energy storage devices, its industrial applicability is recognized.

Claims

1. In a method for controlling a secondary battery, A step of providing a module comprising at least one cell; A step of calculating expected lifespan information for each cell for at least one cell included in the above module; A step of setting a target voltage based on the expected lifespan information for each cell calculated above; and Based on the above-mentioned set target voltage, the step of using different voltages for at least one cell included in the module. Includes, The above target voltage setting is, If the value of the expected lifespan information of the first cell is greater than the value of the expected lifespan information of the second cell, the target voltage set in the second cell is set to be smaller than the target voltage set in the first cell, and A method for controlling a secondary battery, characterized in that when the value of the expected lifespan information of the first cell is smaller than the value of the expected lifespan information of the third cell, the target voltage set in the third cell is set to be greater than the target voltage set in the first cell.

2. In a method for controlling an energy storage device, A step of providing a module comprising at least one cell; A step of calculating expected lifespan information for each cell for at least one cell included in the module when a preset condition is satisfied; A step of setting a target voltage based on the expected lifespan information for each cell calculated above; and Based on the above-mentioned set target voltage, the step of using different voltages for at least one cell included in the module. A method for controlling an energy storage device characterized by including 3. In Paragraph 2, The step of setting the target voltage above is, If the value of the expected lifespan information of the first cell is greater than the value of the expected lifespan information of the second cell, the step of setting the target voltage set in the second cell to be smaller than the target voltage set in the first cell; and If the value of the expected lifespan information of the first cell is smaller than the value of the expected lifespan information of the third cell, the step of setting the target voltage set in the third cell to be greater than the target voltage set in the first cell. A method for controlling an energy storage device characterized by further including 4. In Paragraph 3, A step of comparing the voltage of the above module with the sum of the target voltages set in each cell; and If the above comparison result is not the same, the step of readjusting the target voltage set in the above cell A method for controlling an energy storage device characterized by further including 5. In Paragraph 4, If the above comparison result is the same, a step of determining whether there exists a target voltage exceeding a limit value among the target voltages set in each cell; and If the above judgment result exists, a step of readjusting the target voltage set in each cell. A method for controlling an energy storage device characterized by further including 6. In Paragraph 5, A control method for an energy storage device characterized by a proportional relationship between the numerical value of the expected lifespan information of each cell and the target voltage set for each corresponding cell.

7. In an energy storage device, A module composed of at least one cell; and Calculate life expectancy information for at least one cell included in the above module, and A controller that controls the use of different voltages for at least one cell included in the module based on the above-mentioned expected lifespan information. An energy storage device characterized by including 8. In Paragraph 7, The above controller is, Compare the voltage of the above module with the sum of the target voltages set in each cell, and An energy storage device characterized by readjusting the target voltage set in each cell when the above comparison result is not the same.

9. In Paragraph 8, The above controller is, If the above comparison result is the same, determine whether there exists a target voltage exceeding a limit value among the target voltages set in each cell, and An energy storage device characterized by readjusting the target voltage set in each cell if the above judgment result exists.

10. In Paragraph 9, An energy storage device characterized by a proportional relationship between the numerical value of the expected lifespan information of each cell and the target voltage set for each corresponding cell.

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