Battery control device and method

Abstract

The battery control device according to the present invention includes a connection unit that turns on or turns off the connection state between a plurality of batteries and an output terminal for each battery, and a control unit that controls the connection unit so that the plurality of batteries are connected in parallel to the output terminal and discharged during a first discharge period, which is the period from when the discharge of the plurality of batteries whose SOC is above a predetermined reference value starts until when the SOC of at least one of the plurality of batteries reaches the reference value.

Description

Technical Field

[0001] The present invention relates to a battery control device and method, and more particularly, to a battery control device and method for controlling a plurality of batteries that can be charged and discharged independently of each other.

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0140958 filed on October 20, 2023 and Korean Patent Application No. 10-2024-0052075 filed on April 18, 2024, and all the contents disclosed in the specifications and drawings of the applications are incorporated herein.

Background Art

[0003] Generally, a secondary battery refers to a battery that can be repeatedly charged and discharged. A battery cell, which is the most basic secondary battery, can provide an output voltage of about 2.5V to 4.2V.

[0004] Types of secondary batteries developed so far typically include lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, nickel zinc batteries, and lithium sulfur batteries. Among these, a lithium-sulfur battery has the advantages of being able to store a large amount of energy per unit weight, having a lower manufacturing cost compared to other types of batteries, and being highly safe.

[0005] Recently, as such secondary batteries are applied to devices that require a high output voltage and a large electrical capacity, such as electric vehicles, aircraft, ships, and energy storage systems (ESS), battery modules in which a plurality of battery cells are connected in series and / or in parallel, and battery packs in which a plurality of battery cells or a plurality of battery modules are connected in series and / or in parallel are widely used.

[0006] However, conventional technology, in order to secure a large amount of electrical capacity, involves charging multiple batteries, each capable of independent charging and discharging, and then continuously discharging each charged battery one by one until it is completely discharged. This has the problem of reducing the discharge performance of batteries that experience severe self-discharge when left idle from a high state of charge (SOC) state, such as lithium-sulfur batteries, and increasing the error in the estimated SOC value associated with those batteries. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a battery control device and method that prevents performance degradation due to self-discharge of a battery that experiences severe self-discharge when left in a idle state from a high SOC state, and reduces the error in the estimated SOC value related to the battery.

[0008] Another objective of the present invention is to provide a battery control device and method for improving the discharge capacity and energy density per unit weight of a battery system including multiple batteries.

[0009] Furthermore, another object of the present invention is to provide a battery system and a transport means including a battery control device according to the present invention. [Means for solving the problem]

[0010] A battery control device according to one aspect of the present invention is: A battery control device for controlling the discharge of multiple batteries, comprising: a connection unit configured to be able to turn on or turn off the connection state between the multiple batteries and an output terminal from which a discharge current is output for each battery; and a control unit that controls the connection unit so that the multiple batteries are connected in parallel to the output terminal and discharged during a first discharge period, which is the period from when the discharge of the multiple batteries starts when the SOC (State of Charge) of each of the multiple batteries is above a predetermined reference value until the SOC of at least one of the multiple batteries reaches the reference value; and a control unit that controls the connection unit so that the multiple batteries are connected alternately to the output terminal and discharged during a second discharge period, which is the period from when the SOC of each of the multiple batteries falls below the reference value until the discharge of the multiple batteries is completed.

[0011] In one embodiment, the connection unit may include a plurality of switches, each corresponding to one of the plurality of batteries.

[0012] In one embodiment, the control unit may be configured to discharge each of the plurality of batteries at a first C rate (current rate) during the first discharge period, and to discharge the battery connected to the output terminal among the plurality of batteries at a second C rate higher than the first C rate during the second discharge period.

[0013] In one embodiment, the control unit may be configured to switch the batteries among the plurality of batteries that are not connected to the output terminals to a dormant state during the second discharge period.

[0014] In one embodiment, the control unit may be configured to connect a second battery, selected from the remaining batteries of the plurality of batteries excluding the first battery, to the output terminal and turn off the connection of the first battery when the connection time of the first battery connected to the output terminal elapses during the second discharge period.

[0015] In one embodiment, the second battery may be the battery with the highest voltage among the remaining batteries.

[0016] In one embodiment, the second battery may be the battery among the remaining batteries that has been disconnected from the output terminal for the longest period of time.

[0017] In one embodiment, the control unit may include a data acquisition module configured to acquire data relating to the electrical characteristics of the plurality of batteries using at least one electrical sensor; an SOC information generation module configured to generate SOC information indicating the SOC value of each of the plurality of batteries using the data; and a connection control module configured to control the connection unit according to the SOC values ​​of the plurality of batteries indicated in the SOC information.

[0018] In one embodiment, the plurality of batteries may include at least one lithium-sulfur battery.

[0019] Furthermore, other embodiments of the present invention may include the battery control device described above.

[0020] A battery transport means according to yet another aspect of the present invention includes the battery control device described above.

[0021] A control method according to yet another aspect of the present invention is a battery control method for controlling the discharge of a plurality of batteries, comprising: a first discharge stage in which the plurality of batteries are connected in parallel to an output terminal and discharged during a first discharge period which is the period from when the discharge of the plurality of batteries, each having a State of Charge (SOC) of more than or equal to a predetermined reference value, starts until the SOC of at least one of the plurality of batteries reaches the reference value; and a second discharge stage in which the plurality of batteries are connected alternately to the output terminal and discharged during a second discharge period which is the period from when the SOC of each of the plurality of batteries falls below the reference value until the discharge of the plurality of batteries is completed.

[0022] In one embodiment, during the first discharge stage, each of the plurality of batteries is discharged at a first C rate, and during the second discharge stage, the battery connected to the output terminal among the plurality of batteries may be discharged at a second C rate higher than the first C rate.

[0023] In one embodiment, during the second discharge stage, the batteries among the plurality of batteries that are not connected to the output terminals may be switched to a dormant state.

[0024] In one embodiment, the second discharge step may include a step in which, when the connection time of the first battery connected to the output terminal has elapsed a predetermined reference time, a second battery selected from the remaining batteries of the plurality of batteries excluding the first battery is connected to the output terminal, and the connection of the first battery is turned off. [Effects of the Invention]

[0025] During a first discharge period in which the state of charge (SOC) of each of the plurality of batteries is equal to or higher than a predetermined reference value, the plurality of batteries are connected in parallel to each other to an output terminal and discharged together, thereby preventing performance degradation due to self-discharge of a battery in which self-discharge occurs severely when left unattended from a high-SOC state to a rest state, and reducing an error in the SOC value estimated in relation to the battery.

[0026] Further, during a second discharge period in which the SOC of each of the plurality of batteries is lower than the reference value, the plurality of batteries are alternately connected to the output terminal and discharged, thereby preventing each battery from continuously discharging for a period exceeding a predetermined reference time. As a result, the discharge capacity, energy density, and Coulomb efficiency per unit weight of the battery system including the plurality of batteries can be improved, and an accident due to overheating can be prevented.

[0027] Further, while the plurality of batteries are being discharged, control is performed so that the voltage difference between the plurality of batteries does not increase, thereby preventing an inrush current generated at the moment when batteries with a large voltage difference are connected in parallel to each other. As a result, not only can damage to the battery be prevented and safety be improved, but the charging time can be shortened by enabling the plurality of batteries to be charged simultaneously.

[0028] Further, by enabling the application of a lithium-sulfur battery to a battery system that requires a high capacity, the energy density and safety of the battery system can be improved, and the manufacturing cost can be reduced.

[0029] Furthermore, it will be self-evidently understood from the following description that various embodiments according to the present invention can solve further other technical problems not mentioned above by those having ordinary knowledge in the technical field to which the present invention pertains.

Brief Description of the Drawings

[0030] [Figure 1]This is a block diagram showing a battery control device according to one embodiment of the present invention. [Figure 2] This diagram shows the first connection state between multiple batteries and output terminals. [Figure 3] This diagram shows a second connection state between multiple batteries and output terminals. [Figure 4] This diagram shows a third connection state between multiple batteries and output terminals. [Figure 5] This is a timing diagram showing the discharge sequence of multiple batteries. [Figure 6] This is a flowchart illustrating a battery control method according to one embodiment of the present invention. [Figure 7] This is a flowchart showing the battery connection process for a battery control method according to one embodiment of the present invention. [Figure 8] This graph shows the change in discharge capacity per unit weight as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged at different C rates. [Figure 9] This graph shows the change in energy density as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged at different C rates. [Figure 10] This graph shows the change in Coulomb efficiency as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged at different C rates. [Figure 11] This graph shows the change in discharge capacity per unit weight as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged using different methods. [Figure 12] This graph shows the change in energy density as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged using different methods. [Figure 13] This graph shows the change in Coulomb efficiency as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged using different methods. [Figure 14] This figure shows a battery system according to one embodiment of the present invention. [Figure 15]This figure shows a transportation means according to one embodiment of the present invention. [Modes for carrying out the invention]

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to clarify the solutions to the technical problems of the present invention. However, if describing related prior art would obscure the gist of the present invention, such description may be omitted. Furthermore, the terms used in this specification are defined in consideration of the function of the present invention, and these may change depending on the intentions or conventions of designers, manufacturers, etc. Therefore, the definitions of terms described later should be based on the content of this specification as a whole.

[0032] Figure 1 is a block diagram showing a battery control device 100 according to one embodiment of the present invention.

[0033] As shown in Figure 1, a battery control device 100 according to one embodiment of the present invention includes a connection unit 110 and a control unit 120, and is configured to control the discharge of at least a plurality of batteries.

[0034] Each of the multiple batteries controlled by the battery control device 100 according to the present invention may be embodied as a battery cell, which is the most basic secondary battery, or as a battery module including multiple battery cells connected in series and / or parallel to each other, or as a battery pack including multiple battery cells or multiple battery modules connected in series and / or parallel to each other.

[0035] Furthermore, the plurality of batteries may include at least one lithium-sulfur battery. A lithium-sulfur battery is a battery in which a first active material containing sulfur is applied to the positive electrode and a second active material containing lithium is applied to the negative electrode. Such a lithium-sulfur battery has the advantages of being able to store a large amount of energy per unit weight, having lower manufacturing costs and higher safety compared to other types of batteries.

[0036] The connection unit 110 is configured to allow each battery to be individually turned on or turned off in terms of its connection state to the output terminals from which discharge current is output.

[0037] In one embodiment, the connection unit 110 may include a plurality of switches, each corresponding to a plurality of batteries. In this case, each switch may be configured to electrically connect or disconnect a corresponding battery among the plurality of batteries and the output terminal.

[0038] Each of the multiple switches included in such a connection unit 110 can be embodied in various forms and structures depending on the output of the corresponding battery. For example, each of the multiple switches can be embodied as a relay or as a switching semiconductor element.

[0039] The control unit 120 is configured to control the connection unit 110. That is, by controlling the connection unit 110, the control unit 120 can connect at least one of the plurality of batteries to the output terminal and discharge it.

[0040] In particular, the control unit 120 can control the connection unit 110 so that the multiple batteries are connected in parallel to the output terminals and discharged together during a first discharge period, which is the period from when the discharge of the multiple batteries whose SOC (State of Charge) is above a predetermined reference value starts until the SOC of at least one of the multiple batteries reaches the reference value.

[0041] Furthermore, the control unit 120 can control the connection unit 110 so that the multiple batteries are alternately connected to the output terminals and discharged during a second discharge period, which is the period from when the SOC of each of the multiple batteries falls below the reference value until when the discharge of the multiple batteries is completed.

[0042] In this case, the reference value may be determined by considering the self-discharge rate indicated by the State of Charge (SOC) of the battery controlled by the battery control device 100 according to the present invention. For example, if the battery to be controlled is a lithium-sulfur battery, which experiences severe self-discharge when the SOC is 75% or higher and whose self-discharge rate decreases sharply when the SOC is below 75%, the reference value may be determined to be 75%.

[0043] On the other hand, the control unit 120 may be configured to switch the batteries among the plurality of batteries that are not connected to the output terminals to a dormant state during the second discharge period.

[0044] Furthermore, the control unit 120 may be configured to turn off the connection of the first battery to the output terminal when the connection time of the first battery connected to the output terminal has elapsed a predetermined reference time during the second discharge period, by connecting a second battery selected from the remaining batteries of the plurality of batteries excluding the first battery to the output terminal. The reference time may be determined so that the voltage difference between the batteries does not exceed a predetermined critical value (for example, 10V) due to the discharge of any one of the plurality of batteries.

[0045] In this case, the second battery may be the battery with the highest voltage among the remaining batteries. That is, the control unit 120 may select the second battery with the highest voltage among the remaining batteries as the battery to be discharged after the first battery.

[0046] In one embodiment, the second battery may be the battery among the remaining batteries that has been disconnected from the output terminal for the longest period of time. That is, the control unit 120 may select the second battery among the remaining batteries that has been disconnected from the output terminal for the longest period of time as the battery to be discharged after the first battery.

[0047] Thus, the present invention prevents battery damage and improves safety by controlling the voltage difference between the multiple batteries to prevent it from becoming large while the multiple batteries are being discharged, thereby preventing the inrush current that occurs when batteries with a large voltage difference are connected in parallel. In addition, it shortens the charging time by enabling the simultaneous charging of multiple batteries.

[0048] On the other hand, as described above, the control unit 120 controls the connection unit 110 so that during the first discharge period each of the plurality of batteries is discharged at a first C rate (current rate), and during the second discharge period the battery connected to the output terminal among the plurality of batteries is discharged at a second C rate which is higher than the first C rate.

[0049] In another embodiment, the control unit 120 may adjust the C-rate of the plurality of batteries by adjusting the duty cycle of the discharge current discharged in each of the plurality of batteries, or by controlling the output of an electrical device that uses the discharge current.

[0050] Thus, the present invention prevents performance degradation due to self-discharge in batteries that experience severe self-discharge when left idle from a high SOC state, by connecting the multiple batteries in parallel to each other at the output terminals and discharging them together during a first discharge period in which the SOC of each of the multiple batteries is above a predetermined reference value, and reduces the error in the estimated SOC value in relation to the battery.

[0051] Furthermore, the present invention prevents each battery from being continuously discharged beyond a predetermined reference time by alternately connecting the plurality of batteries to the output terminal and discharging them during a second discharge period in which the SOC of each of the plurality of batteries falls below the reference value. This improves the discharge capacity per unit weight, energy density, and Coulomb efficiency of the battery system including the plurality of batteries, and prevents accidents due to overheating.

[0052] Therefore, the present invention can solve the problems of lithium-sulfur batteries, which exhibit a high self-discharge rate in a high state of charge (SOC) state and have a relatively low discharge current compared to other types of batteries, and can expand the range of applications for lithium-sulfur batteries.

[0053] In one embodiment, the control unit 120 may include a data acquisition module 122, a SOC information generation module 124, and a connection control module 126.

[0054] The data acquisition module 122 may be configured to acquire data relating to the electrical characteristics of the plurality of batteries using at least one electrical sensor. In this case, the electrical characteristics may include the voltage and current values ​​of each of the plurality of batteries.

[0055] The SOC information generation module 124 may be configured to generate SOC information indicating the SOC value of each of the multiple batteries using data acquired by the data acquisition module 122. For example, the SOC information generation module 124 may generate the SOC information using an SOC-OCV profile that shows the correspondence between the SOC (State of Charge) and OCV (Open Circuit Voltage) of each battery, or using a current integration method.

[0056] The connection control module 126 may be configured to control the connection unit 110 based on the SOC values ​​of the plurality of batteries indicated in the SOC information.

[0057] That is, the connection control module 126 can control the connection unit 110 so that the multiple batteries are connected in parallel to the output terminal and discharged together during a first discharge period in which the SOC of each of the multiple batteries is all above a predetermined reference value. For example, while the SOC of each of the multiple batteries decreases from 100% to 75%, the connection control module 126 can connect the multiple batteries in parallel to the output terminal.

[0058] Subsequently, the connection control module 126 can control the connection unit 110 so that the plurality of batteries are alternately connected to the output terminals and discharged during a second discharge period in which the SOC of each of the plurality of batteries falls below the reference value.

[0059] For example, if the state of charge (SOC) of each of the multiple batteries falls below 75% due to the discharge of the multiple batteries, the connection control module 126 may disconnect the parallel connection between the multiple batteries and alternately connect the multiple batteries to the output terminals.

[0060] On the other hand, if, during the first discharge period, the plurality of batteries are discharged simultaneously, but the SOC of only some of the plurality of batteries falls below the reference value, while the SOC of the remaining batteries remains above the reference value, the control unit 120 may maintain the plurality of batteries connected in parallel to the output terminal until the SOC of all of the plurality of batteries falls below the reference value.

[0061] In another embodiment, if, during the first discharge period, the plurality of batteries are discharged simultaneously, but the SOC of only some of the batteries falls below the reference value, while the SOC of the remaining batteries remains above the reference value, the control unit 120 may be configured to turn off the connection between some of the batteries and the output terminal to switch those batteries into a dormant state, while maintaining the connection between the remaining batteries and the output terminal.

[0062] The aforementioned control unit 120 may include one or more general-purpose processors or ASICs (application-specific integrated circuits) for executing the battery control logic, and may further include hardware such as registers and memory depending on the embodiment. Such a control unit 120 can be realized by a combination of hardware such as a processor and software such as a computer program. That is, the battery control logic of the connection unit 110 may be realized as a computer program, stored in the control unit 120's own memory or in a storage unit 130 described later, and the stored computer program may be configured to be executed by the hardware of the control unit 120.

[0063] In one embodiment, the battery control device 100 may further include a storage unit 130. The storage unit 130 may be configured to store and manage data necessary for the operation of the battery control device 100. For this purpose, the storage unit 130 may include one or more of the following: ROM (read-only memory), RAM (random access memory), EEPROM (electrically erasable programmable read-only memory), registers, flash memory (registered trademark), CD-ROM, magnetic tape, hard disk, floppy disk, and optical data recording device.

[0064] In one embodiment, the battery control device 100 may be configured to work in conjunction with a measuring device 12 that includes at least one electrical sensor for measuring the voltage, charging current, and / or discharging current of each of the plurality of batteries, a charging device 14 for charging the plurality of batteries, a communication device 16 for communicating with other devices, and so on.

[0065] In another embodiment, the battery control device 100 according to the present invention may include at least one of the measuring device 12, charging device 14, and communication device 16 described above.

[0066] Figure 2 shows the first connection state between multiple batteries and output terminals.

[0067] As shown in Figure 2, the connection unit 110 of the battery control device according to the present invention is configured to allow the connection state between a battery group BG including a plurality of batteries B1, B2, and B3 and an output terminal BT from which discharge current is output to be turned on or turned off for each battery individually. For this purpose, the connection unit 110 may include a plurality of switches S1, S2, and S3 corresponding to the plurality of batteries B1, B2, and B3, respectively.

[0068] As described above, the plurality of switches S1, S2, and S3 can each be realized in various forms and structures depending on the output of the corresponding battery. For example, if the plurality of batteries B1, B2, and B3 each consist of a battery module or battery pack containing a plurality of battery cells connected in series and / or parallel to each other, the plurality of switches S1, S2, and S3 can each be realized as relays.

[0069] During the first discharge period, which is the period from when the discharge of the plurality of batteries B1, B2, and B3 begins until the State of Charge (SOC) of at least one of the plurality of batteries reaches the reference value (for example, 75%), the control unit 120 can turn on all of the plurality of switches S1, S2, and S3 to connect the plurality of batteries B1, B2, and B3 in parallel to the output terminal BT and discharge them together.

[0070] In this case, each of the multiple batteries B1, B2, and B3 can be discharged at a first C rate. For example, each battery may be discharged at a C rate of 0.1C, and a total discharge current of 0.3C may be output to the output terminal BT.

[0071] Figure 3 shows a second connection state between multiple batteries and output terminals.

[0072] As shown in Figure 3, during the second discharge period, which is the period from when the State of Charge (SOC) of each of the plurality of batteries B1, B2, and B3 falls below the reference value until the discharge of the plurality of batteries is completed, the control unit 120 can control the connection unit 110 so that the plurality of batteries are alternately connected to the output terminals and discharged.

[0073] For example, the control unit 120 can maintain the connection state of the first switch S1 among the plurality of switches S1, S2, and S3, and turn off the remaining switches S2 and S3, thereby connecting only the first battery B1 among the plurality of batteries B1, B2, and B3 to the output terminal BT.

[0074] In this case, the first battery B1 connected to output terminal BT may be discharged at a second C rate higher than the first C rate, and the remaining batteries B2 and B3 may be switched to a dormant state. For example, the first battery B1 may be discharged at a C rate of 0.3C, and a total discharge current of 0.3C may be output to output terminal BT.

[0075] Figure 4 shows a third connection state between multiple batteries and output terminals.

[0076] As shown in Figure 4, when the connection time of the first battery B1 connected to the output terminal BT has elapsed for a predetermined reference time, the control unit 120 may connect the second battery B2, selected from the remaining batteries B2 and B3 excluding the first battery B1, to the output terminal BT and turn off the connection of the first battery B1.

[0077] In this case, the second battery B2 may be the battery with the highest voltage among the remaining batteries B2 and B3, or the battery that has been disconnected from the output terminal BT for the longest period of time among the remaining batteries B2 and B3.

[0078] The control unit 120 maintains the disconnected state of the third switch S3 among the plurality of switches S1, S2, and S3, and turns on the second switch S2 and turns off the first switch S1, thereby connecting only the second battery B2 among the plurality of batteries B1, B2, and B3 to the output terminal BT.

[0079] In this case, the second battery B2 connected to the output terminal BT is discharged at a second C rate higher than the first C rate, while the first battery B1 is switched to a dormant state and the third battery B3 can remain in a dormant state. For example, the second battery B2 may be discharged at a C rate of 0.3C, and a total discharge current of 0.3C may be output to the output terminal BT.

[0080] Figure 5 is a timing diagram showing the discharge sequence of multiple batteries.

[0081] As shown in Figure 5, the multiple batteries B1, B2, and B3 controlled by the present invention are discharged together during the first discharge period t1-to of the overall discharge period.

[0082] On the other hand, the multiple batteries B1, B2, and B3 are discharged alternately from the first discharge period t1-to onward. In this case, each battery may repeatedly discharge and rest until the end of discharge. For example, each battery may repeatedly discharge for a period of T time and rest for a period of 2T time.

[0083] Figure 6 is a flowchart illustrating a battery control method according to one embodiment of the present invention.

[0084] As shown in Figure 6, the battery control method according to the present invention is a method for controlling the discharge of at least a plurality of batteries, comprising a first discharge step and a second discharge step.

[0085] In the first discharge stage, multiple batteries whose respective SOC is above a predetermined reference value are connected in parallel to the output terminals and discharged together for a first discharge period, which is the period from when the discharge starts until at least one of the multiple batteries reaches the reference value (S610~S650).

[0086] In the first discharge stage, each of the plurality of batteries can be discharged at a first C rate.

[0087] Furthermore, in the second discharge stage, the plurality of batteries are alternately connected to the output terminals and discharged for a second discharge period, which is the period from when the state of charge (SOC) of each battery falls below the reference value until the discharge of the plurality of batteries is completed (S610~S640, S650).

[0088] In the second discharge stage, the battery connected to the output terminal among the plurality of batteries may be discharged at a second C rate higher than the first C rate.

[0089] Furthermore, during the second discharge stage, any of the batteries not connected to the output terminals may be switched to a dormant state.

[0090] Furthermore, in the second discharge stage, when the connection time of the first battery connected to the output terminal has elapsed a predetermined reference time, a second battery selected from the remaining batteries of the plurality of batteries excluding the first battery is connected to the output terminal, and the connection of the first battery may be turned off.

[0091] In one embodiment, the plurality of batteries may include at least one lithium-sulfur battery.

[0092] Specifically, the data acquisition module 122 of the control unit 120 acquires data related to the electrical characteristics of the plurality of batteries using at least one electrical sensor (S610). In this case, the electrical characteristics may include the voltage and current values ​​of each of the plurality of batteries.

[0093] Subsequently, the SOC information generation module 124 of the control unit 120 generates SOC information indicating the SOC value of each of the multiple batteries using the data acquired by the data acquisition module 122 (S620). For example, the SOC information generation module 124 can generate the SOC information using an SOC-OCV profile that shows the correspondence between the SOC and OCV of each battery, or using a current integration method.

[0094] As a result, the connection control module 126 of the control unit 120 can control the connection unit 110 based on the SOC values ​​of the multiple batteries indicated in the SOC information.

[0095] In other words, the connection control module 126 compares the SOC values ​​of the plurality of batteries with a reference value Rc (S630).

[0096] If, as a result of comparing the SOC values ​​of the multiple batteries with the reference value Rc, the SOC of each of the multiple batteries is equal to or greater than the reference value Rc, the connection control module 126 connects the multiple batteries in parallel to the output terminals and discharges them together (S640, S650).

[0097] For example, if the reference value Rc is 75% and the SOC of each of the plurality of batteries is in the range of 100% to 75%, the connection control module 126 may connect the plurality of batteries in parallel and connect them to the output terminal. In this case, each of the plurality of batteries can be discharged at the first C rate.

[0098] On the other hand, if, as a result of the discharge of the multiple batteries, the State of Charge (SOC) of each of the multiple batteries falls below the reference value Rc, the connection control module 126 alternately connects the multiple batteries to the output terminals and discharges them one by one.

[0099] For example, if the reference value Rc is 75% and the SOC of each of the multiple batteries is all lower than 75%, the connection control module 126 may disconnect the parallel connection between the multiple batteries and connect the multiple batteries alternately to the output terminal. In this case, the battery connected to the output terminal among the multiple batteries may be discharged at a second C rate higher than the first C rate.

[0100] The process described above, S610 to S660, may be repeated until the discharge of the multiple batteries is complete (S670).

[0101] Figure 7 is a flowchart showing the battery connection process of a battery control method according to one embodiment of the present invention.

[0102] As shown in Figure 7, if, as a result of the discharge of the multiple batteries, the State of Charge (SOC) of each of the multiple batteries falls below the reference value Rc, the connection control module 126 of the connection unit 110 may alternately connect the multiple batteries to the output terminals and discharge them one by one.

[0103] Specifically, if, as a result of the discharge of the multiple batteries, the State of Charge (SOC) of each of the multiple batteries falls below the reference value Rc, the connection control module 126 turns off the connections of the remaining batteries among the multiple batteries, excluding the selected first battery, thereby connecting only the first battery among the multiple batteries to the output terminal (S710).

[0104] In this case, the control unit 120 can maintain the connection state of the first battery until a predetermined reference time has elapsed (S720, S730). During the reference time, the remaining battery can be kept in a dormant state.

[0105] Subsequently, when the connection time of the first battery connected to the output terminal has elapsed to a predetermined reference time, the connection control module 126 connects a second battery, selected from the remaining batteries excluding the first battery, to the output terminal and turns off the connection of the first battery, thereby connecting only the second battery among the plurality of batteries to the output terminal (S740).

[0106] In this case, the second battery may be the battery with the highest voltage among the remaining batteries, or the battery that has been disconnected from the output terminal for the longest period of time among the remaining batteries.

[0107] The process described above, S720 to S740, may be repeated until the discharge of the multiple batteries is complete (S750).

[0108] Figure 8 is a graph showing the change in discharge capacity per unit weight as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged at different C rates.

[0109] Figure 9 is a graph showing the change in energy density as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged at different C rates.

[0110] Figure 10 is a graph showing the change in coulombic efficiency as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged at different C rates.

[0111] In Figures 8 to 10, "CASE 1" is the case where the lithium-sulfur battery is repeatedly charged at 0.2C and discharged at 0.1C, "CASE 2" is the case where the lithium-sulfur battery is repeatedly charged at 0.2C and discharged at 0.3C, and "CASE 3" is the case where the lithium-sulfur battery is repeatedly charged at 0.2C and discharged at 0.5C.

[0112] As shown in Figures 8 to 10, when the C rate during charging is the same, it can be seen that the discharge efficiency, energy density, and Coulomb efficiency of the lithium-sulfur battery change stably regardless of the increase in the number of cycles as the C rate during discharge increases.

[0113] Therefore, in this invention, when the SOC of the battery to be discharged is relatively high, the battery is simultaneously discharged at a relatively low C rate for self-discharge, but when the SOC of the battery to be discharged is relatively low, the battery is discharged alternately at a relatively high C rate.

[0114] Figure 11 is a graph showing the change in discharge capacity per unit weight as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged using different methods.

[0115] Figure 12 is a graph showing the change in energy density as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged using different methods.

[0116] Figure 13 is a graph showing the change in Coulomb efficiency as the number of charge-discharge cycles increases for lithium-sulfur batteries discharged using different methods.

[0117] In Figures 11 to 13, the "present invention" is a method in which, when the SOC of each of the multiple lithium-sulfur batteries is 75% or more, the multiple lithium-sulfur batteries are connected in parallel and discharged simultaneously at 0.1C, and when the SOC of each falls below 75%, the multiple lithium-sulfur batteries are discharged alternately at 0.3C.

[0118] Furthermore, "Comparative Example 1" is a method in which the state of charge (SOC) of multiple lithium-sulfur batteries is not considered, and each battery is discharged completely one by one in sequence at 0.3C.

[0119] Furthermore, "Comparative Example 2" is a method in which, when the SOC of each of the multiple lithium-sulfur batteries is 75% or higher, the multiple lithium-sulfur batteries are connected in parallel and discharged simultaneously at 0.1C. When the SOC of each falls below 75%, the multiple lithium-sulfur batteries are discharged one by one sequentially and completely at 0.3C.

[0120] As shown in Figures 11 to 13, it can be seen that the method according to the "present invention" can improve the discharge efficiency, energy density, and Coulomb efficiency of the lithium-sulfur battery compared to the methods according to "Comparative Example 1" and "Comparative Example 2".

[0121] Figure 14 shows a battery system 10 according to one embodiment of the present invention.

[0122] As shown in Figure 14, the battery system 10 may include a battery group BG comprising a plurality of batteries B1 to Bn, each capable of being charged and discharged independently, an output terminal BT that outputs the discharge current of the battery group BG, and a battery control device 100 according to the present invention. In one embodiment, the battery system 10 may further include at least one of a measuring device 12, a charging device 14, and a communication device 16.

[0123] The measuring device 12 may be configured to measure the voltage, charging current, and / or discharging current of a plurality of batteries B1 to Bn. For this purpose, the measuring device 12 may include at least one electrical sensor.

[0124] For example, the measuring device 12 may include at least one voltage sensor that senses the voltages of multiple batteries B1 to Bn and / or at least one current sensor that senses the currents of multiple batteries B1 to Bn.

[0125] A battery control device 100 according to one embodiment of the present invention can acquire the voltage values ​​of a plurality of batteries B1 to Bn using the measuring device 12.

[0126] The charging device 14 may be configured to charge a plurality of batteries B1 to Bn. In this case, the battery control device 100 according to one embodiment of the present invention may be configured to control the operation of the charging device 14 to proceed with or interrupt the charging of the plurality of batteries B1 to Bn, or to change the charging conditions.

[0127] The communication device 16 may be configured to communicate with other remote devices. For example, the communication device 16 may be configured to receive data transmitted from remote servers or communication terminals via wired and / or wireless communication networks and transmit it to the battery control device 100, or to transmit data generated by the battery control device 100 to other servers or communication terminals. For this purpose, the communication device 16 may include a communication modem for wired and / or wireless communication.

[0128] Figure 15 shows a transport means 2 according to one embodiment of the present invention.

[0129] As shown in Figure 15, a transport means 2 according to one embodiment of the present invention may include a battery system 10 that provides the electrical energy necessary for the operation of the transport means 2, and a battery control device 100 according to the present invention.

[0130] In one embodiment, the battery control device 100 according to the present invention may be configured to be linked to or integrated with an ECU (Electronic Control Unit) that controls the operation of the transport means 2, and a BMS (Battery Management System) of the battery system 10.

[0131] Furthermore, the battery control device 100 may be configured to receive data transmitted from a remote server 4 via a wired and / or wireless communication network, or to transmit data generated by the battery control device 100 to the server 4.

[0132] Figure 15 shows a vehicle as the means of transport 2 according to the present invention, but the means of transport 2 according to the present invention may also be an aircraft or a ship.

[0133] For reference, the battery control device 100 according to the present invention is applicable to a variety of electrical devices and systems in addition to means of transport such as vehicles, aircraft, and ships, and is also applicable to ESS (Energy Storage System).

[0134] As described above, the present invention prevents performance degradation due to self-discharge of batteries that would otherwise experience severe self-discharge if left idle from a high SOC state, by connecting the multiple batteries in parallel to the output terminals and discharging them together during a first discharge period in which the SOC of each battery is above a predetermined reference value, and reduces the error in the estimated SOC value in relation to the battery.

[0135] Furthermore, the present invention prevents each battery from being continuously discharged beyond a predetermined reference time by alternately connecting the plurality of batteries to the output terminal and discharging them during a second discharge period in which the SOC of each of the plurality of batteries falls below the reference value. This improves the discharge capacity per unit weight, energy density, and Coulomb efficiency of the battery system including the plurality of batteries, and prevents accidents due to overheating.

[0136] Furthermore, the present invention prevents inrush current that occurs when batteries with a large voltage difference are connected in parallel by controlling the voltage difference between the multiple batteries so that it does not become large while the multiple batteries are being discharged. This not only prevents battery damage and improves safety, but also shortens the charging time by enabling the simultaneous charging of multiple batteries.

[0137] Furthermore, the present invention enables the application of lithium-sulfur batteries to battery systems requiring high capacity, thereby improving the energy density and safety of such battery systems while also reducing manufacturing costs.

[0138] Consequently, embodiments of the present invention can certainly solve a variety of other technical problems not only in the relevant technical field but also in related technical fields, beyond those mentioned herein.

[0139] The present invention has been described above with reference to specific embodiments. However, those skilled in the art will clearly understand that a variety of modified embodiments can be realized within the technical scope of the present invention. Therefore, the above-described embodiments should be considered from an explanatory rather than restrictive viewpoint. That is, the true technical idea of ​​the present invention is shown in the claims, and all differences within the equivalent scope should be interpreted as being included in the present invention. [Explanation of symbols]

[0140] 2 Means of transportation 10 Battery System 100 Battery Control Unit 110 Connection Unit 120 Control Unit 122 Data Acquisition Module 124 SOC Information Generation Module 126 Connection Control Module 130 storage units

Claims

1. A battery control device that controls the discharge of multiple batteries, A connection unit configured to allow the connection state between the plurality of batteries and the output terminal from which discharge current is output to be turned on or turned off for each battery, A battery control device comprising: a battery control device, which controls the connection unit so that the plurality of batteries are connected in parallel to the output terminals and discharged during a first discharge period, which is the period from when the discharge of the plurality of batteries starts when the State of Charge (SOC) of each of the plurality of batteries is above a predetermined reference value until the SOC of at least one of the plurality of batteries reaches the reference value; and a control unit so that the plurality of batteries are connected alternately to the output terminals and discharged during a second discharge period, which is the period from when the SOC of each of the plurality of batteries falls below the reference value until the discharge of the plurality of batteries is completed.

2. The aforementioned connection unit is The battery control device according to claim 1, characterized in that it includes a plurality of switches corresponding to each of the plurality of batteries.

3. The control unit is The battery control device according to claim 1, characterized in that during the first discharge period, each of the plurality of batteries is discharged at a first C rate, and during the second discharge period, the battery connected to the output terminal among the plurality of batteries is discharged at a second C rate higher than the first C rate.

4. The control unit is The battery control device according to claim 1, characterized in that during the second discharge period, the battery among the plurality of batteries that is not connected to the output terminal is switched to a dormant state.

5. The control unit is The battery control device according to claim 1, characterized in that, during the second discharge period, when the connection time of the first battery connected to the output terminal elapses to a predetermined reference time, a second battery selected from the remaining batteries of the plurality of batteries excluding the first battery is connected to the output terminal, and the connection of the first battery is turned off.

6. The second battery is, The battery control device according to claim 5, characterized in that it is the battery with the highest voltage among the remaining batteries.

7. The second battery is, The battery control device according to claim 5, characterized in that, among the remaining batteries, it is the battery that has not been connected to the output terminal for the longest period of time.

8. The control unit is A data acquisition module that acquires data related to the electrical characteristics of the plurality of batteries using at least one electrical sensor, An SOC information generation module that generates SOC information indicating the SOC value of each of the multiple batteries using data, The battery control device according to claim 1, further comprising a connection control module that controls the connection unit based on the SOC values ​​of the plurality of batteries indicated in the SOC information.

9. The aforementioned multiple batteries are The battery control device according to claim 1, characterized by comprising at least one lithium-sulfur battery.

10. A battery system comprising a battery control device according to any one of claims 1 to 9.

11. A transport means comprising a battery control device according to any one of claims 1 to 9.

12. A battery control method for controlling the discharge of multiple batteries, A first discharge stage in which the multiple batteries are connected in parallel to each other to the output terminals and discharged during a first discharge period which is the period from the time when the discharge of the multiple batteries whose SOC is above a predetermined reference value is started until the time when the SOC of at least one of the multiple batteries reaches the reference value, A battery control method, comprising: a second discharge stage in which the plurality of batteries are alternately connected to the output terminals and discharged during a second discharge period, which is the period from when the SOC of each of the plurality of batteries falls below the reference value until when the discharge of the plurality of batteries is completed.

13. In the first discharge stage, each of the plurality of batteries is discharged at a first C rate. The battery control method according to claim 12, characterized in that, in the second discharge stage, the battery connected to the output terminal among the plurality of batteries is discharged at a second C rate higher than the first C rate.

14. The battery control method according to claim 12, characterized in that, in the second discharge stage, the battery among the plurality of batteries that is not connected to the output terminal is switched to a dormant state.

15. The second discharge stage described above is: A battery control method according to any one of claims 12 to 14, characterized in that when the connection time of the first battery connected to the output terminal elapses a predetermined reference time, a second battery selected from the remaining batteries of the plurality of batteries excluding the first battery is connected to the output terminal, and the connection of the first battery is turned off.

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