Battery pack

Abstract

One embodiment of the present invention provides a battery pack comprising: a battery module array having first and second terminals, comprising a plurality of battery modules connected in series—each of which includes at least one battery cell, a current cutoff element connected in series with the battery cell and opening when an overcurrent is applied, and a sensor unit that measures state information of the battery cell and transmits a measured value—; a battery cutoff unit comprising a first switch unit connected in series with the first terminal, a second switch unit connected in series with the second terminal, and a third switch unit connecting the first and second terminals; and a battery management system that turns on the third switch unit to short-circuit the first and second terminals and opens the current cutoff element when the measured value transmitted from the sensor unit exceeds a preset threshold value.

Description

Technology Field

[0001] The present invention relates to a battery pack. Background Technology

[0003] A secondary battery is a battery that can be recharged and discharged and used repeatedly. It consists of a single battery cell and is used in small portable electronic devices such as mobile phones, laptops, computers, cameras, and camcorders, or consists of a battery pack containing multiple battery cells and can be used as a power source for driving motors in high-output hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0004] Batteries used in hybrid electric vehicles (HEVs) or electric vehicles (EVs) must achieve high output and high capacity. For this reason, multiple batteries are configured as a single unit to form a battery pack, and by electrically connecting multiple such battery packs in series or parallel, they are operated as a high-capacity and high-output power source.

[0005] As such, as battery packs are driven by high-capacity, high-output power sources, they are being improved to have increasingly higher energy densities. However, as battery packs achieve higher energy densities, thermal runaway can occur, where if some battery modules are damaged, the temperature of the undamaged modules rises rapidly and explodes. Such thermal runaway in battery packs poses a significant risk to user safety. The problem to be solved

[0007] One of the problems to be solved by the present invention is to provide a battery pack in which thermal runaway is prevented. means of solving the problem

[0009] One embodiment of the present invention provides a battery pack comprising: a battery module array having first and second terminals, comprising a plurality of battery modules connected in series—each of which includes at least one battery cell, a current cutoff element connected in series with the battery cell and opening when an overcurrent is applied, and a sensor unit that measures state information of the battery cell and transmits a measured value—; a battery cutoff unit comprising a first switch unit connected in series with the first terminal, a second switch unit connected in series with the second terminal, and a third switch unit connecting the first and second terminals; and a battery management system that turns on the third switch unit to short-circuit the first and second terminals and opens the current cutoff element when the measured value transmitted from the sensor unit exceeds a preset threshold value. Effects of the invention

[0011] A battery pack according to the technical concept of the present invention can prevent a problem occurring in some battery modules from spreading into a thermal runaway affecting neighboring battery modules by electrically isolating the battery modules constituting the battery pack from each other when there is a possibility that a problem in some battery modules may escalate into a thermal runaway.

[0013] The various and beneficial advantages and effects of the present invention are not limited to those described above and may be more easily understood in the process of explaining specific embodiments of the present invention. Brief explanation of the drawing

[0015] FIG. 1 is a schematic block diagram of a battery pack according to one embodiment of the present invention. Figure 2 is a block diagram illustrating the control of a battery management system. FIGS. 3 to 5 are drawings for explaining the explosion prevention function of the battery pack of FIG. 1. Specific details for implementing the invention

[0016] Specific details of other embodiments are included in the detailed description and drawings.

[0017] 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. Throughout the specification, the same reference numerals refer to the same components.

[0019] With reference to FIGS. 1 and FIGS. 2, a battery pack according to one embodiment will be described. FIG. 1 is a schematic block diagram of a battery pack according to one embodiment of the present invention, and FIG. 2 is a block diagram for explaining the control of a battery management system.

[0021] Referring to FIG. 1, a battery pack (10) according to one embodiment of the present invention may include a battery module array (100) having first and second terminals (N1, N2), a battery cutoff unit (200) connected to the first and second terminals (N1, N2) of the battery module array (100), and a battery management system (300). The battery pack (10) may include first and second output terminals (CP, CN) for supplying current to an external device (20).

[0023] A battery module array (100) may include a plurality of battery modules (110) connected in series. Each of the plurality of battery modules (110) may include one or more battery cells (111), and may include a current cutoff element (112) connected in series with the battery cells (111) and a sensor unit (113). When a plurality of battery cells (111) are employed in the battery module (110), the plurality of battery cells (111) may be connected to each other in series, parallel, and series-parallel. In one embodiment, the battery module array (100) may have a structure in which the first to sixth battery modules (110-1 to 110-6) are connected in series. According to the embodiment, a manual service cutoff module (120) may be connected in series to the battery module (110).

[0024] The battery cell (111) may be a various type of secondary battery capable of repeated charging and discharging. In one embodiment, the battery cell (111) may be a lithium-ion battery.

[0026] The current blocking element (112) is a device that opens when an overcurrent flows through the battery module (110) to protect the battery module (110). In one embodiment, it may be a fuse, but is not limited thereto. The current blocking element (112) opens when an overcurrent flows through the battery module (110), thereby separating a plurality of series-connected battery modules (110) into separate individual battery modules (110).

[0028] The sensor unit (113) can measure the status information of the battery module (110) and transmit the measured value to the battery management system (300). The sensor unit (113) may include various sensors that measure the status information of the battery module (110). Additionally, the sensor unit (113) may be composed of a plurality of sensors. For example, the sensor unit (113) may include a temperature sensor and a gas sensor, the temperature sensor may measure the temperature of the battery module (110) and transmit the measured value to the battery management system (300), and the gas sensor may measure the gas concentration occurring within the battery module (110) and transmit the measured value to the battery management system (300).

[0030] Referring to FIGS. 1 and 2, the battery management system (300) can receive a measurement value transmitted from a sensor unit (113) placed in each battery module (110), and can determine whether the battery module (110) is operating normally by comparing the measurement value with a previously stored threshold value. If the measurement value detected by the sensor unit (113) is below a preset threshold value, the battery module (110) can be determined to be in a 'normal state' where it is operating normally, and if the detected measurement value exceeds a preset threshold value, the battery module (110) can be determined to be in an 'abnormal state' where it is not operating normally. Such an abnormal state of the battery module (110) may occur when the battery cell is damaged by external factors such as impact. Ignition may begin in a battery module (110) that has exceeded a threshold value, and the heat generated from the ignited battery module (110) is transferred to an adjacent battery module (110), causing the entire battery module array (100) to ignite and emit flammable gas. In this case, if the battery module array (100) is in a high-voltage energy state, a so-called 'large-scale explosion' may occur, in which the entire battery module array (100) explodes beyond simple ignition. Such large-scale explosions become more severe when the battery module array (100) is in a high-voltage state. In one embodiment, the battery pack (10) can reduce the large-scale explosion to a small-scale explosion or stop it as simple ignition by electrically separating the multiple battery modules (110) of the battery module array (100) from each other and changing them to a low-voltage state before the battery module array (100) explodes in this manner. This will be described in detail later.

[0032] The threshold value for which the battery management system (300) determines an abnormal state is a pre-stored value, and various values ​​that can be compared with the measurement value transmitted from the sensor unit (113) may be pre-stored. For example, if the temperature is measured by the sensor unit (113), the threshold value may be the temperature value. Also, if the gas concentration is measured by the sensor unit (113), the threshold value may be the gas concentration value. Also, if the voltage is measured, the threshold value may be the voltage value. Specifically, for example, if the temperature is measured by the sensor unit (113) and the battery cell included in the battery module (110) is a lithium-ion battery cell, the threshold value may be 50°C. Also, if the voltage is measured by the sensor unit (113), the threshold value may be based on a value where the discharge rate of 50 Crate or higher is sustained for several seconds.

[0033] Additionally, the battery management system (300) can determine that the battery module (110) is in an abnormal state even if the measurement value transmitted from the sensor unit (113) of one of the multiple battery modules (110) is more than 3°C higher than the measurement value transmitted from the sensor unit (113) of the other battery module (110).

[0034] Additionally, the battery management system (300) can determine an abnormal state only when both the measured value from the temperature sensor and the measured value from the gas sensor exceed a threshold value, provided that the sensor unit (113) includes both a temperature sensor and a gas sensor.

[0036] When the battery module (110) is determined to be in a normal state, the battery management system (300) can turn on the first and second switch sections (210, 220) to supply current from the battery module array (100) to an external device (20). Additionally, when the battery module (110) is determined to be in an abnormal state, the battery management system (300) can turn on the third switch section (230) to short-circuit the battery module array (100), and by causing an overcurrent to flow through the short-circuited battery module array (100), the current blocking element (112) configured in each battery module can be opened, thereby electrically disconnecting each battery module and preventing thermal runaway problems in advance.

[0037] Referring to FIG. 1, a battery cutoff unit (200) is positioned between a battery module array (100) and an external device (20) and can cut off the current transmitted from the battery pack (10) to the external device (20) under the control of a battery management system (300). That is, the input portion of the battery cutoff unit (200) can be connected to the first and second terminals (N1, N2) of the battery module array (100), and the output portion can be connected to the first and second output terminals (CP, CN) of the battery pack (10).

[0038] The battery cutoff unit (200) may include a first switch section (210) connected in series with a first terminal (N1), a second switch section (220) connected in series with a second terminal (N2), and a third switch section (230) connecting the first and second terminals (N1, N2) to each other. The first to third switch sections (210 to 230) may be composed of various types of switch elements. At least one of the first to third switch sections (210 to 230) may be composed of a plurality of switch elements, and a resistor element may be further disposed in any one of the switch sections. In one embodiment, the first switch section (210) may have first and second switch elements (211, 212) connected in parallel with each other, and may further include a resistor element (213) connected in series with the second switch element (212).

[0039] In one embodiment, the first to third switch sections (210 to 230) may be composed of power relays. The first to third switch sections (210 to 230) may be turned ON or OFF according to the control of the battery management system (300) to cut off the current flowing through the first to third switch sections (210 to 230). When the battery module array (100) is in a normal state, the first and second switch sections (210, 220) may be turned ON so that the current supplied from the battery module array (100) is supplied to an external device (20). Additionally, when the battery module array (100) is in an abnormal state, the third switch section (230) may be turned ON so that the first and second terminals (N1, N2) of the battery module array (100) are short-circuited to each other. When the first and second terminals (N1, N2) are short-circuited to each other, an overcurrent occurs in the battery module array (100), and the current blocking element (112) included in each battery module (110) included in the battery module array (100) can be opened. Accordingly, each battery module (110) included in the battery module array (100) can be electrically separated from each other. Since this separates a single high-capacity, high-output battery module array (100) into multiple low-capacity, low-output battery modules (110), it is possible to prevent thermal runaway from occurring in the battery pack (10) in a high-capacity, high-output state.

[0041] This will be explained in detail with reference to FIGS. 3 to 5.

[0042] FIG. 3 is a case where the battery module (110) of the battery pack (10) is in a normal state, and the first and second switch parts (210, 220) of the battery cutoff unit (200) are each turned on, so that the current (I1) supplied from the battery module array (100) can be supplied to an external device (20).

[0044] FIG. 4 illustrates a case where one of the battery modules (110) of the battery pack (10) is in an abnormal state. In one embodiment, it is assumed that the first battery module (110-1) is damaged and in an abnormal state. Since the first battery module (110-1) in an abnormal state ignites and its internal temperature rises rapidly, the sensor unit (113) may measure a high temperature above a preset threshold or detect a high concentration of gas. Since the measurement value transmitted from the sensor unit (113) exceeds the preset threshold, the battery management system (300) may apply an ON signal to the third switch unit (230) of the battery cutoff unit (200) to short-circuit the first and second terminals (N1, N2) of the battery module array (100). According to an embodiment, the third switch unit (230) may be short-circuited and the first and second switch units (220) may be open. When the first and second terminals (N1, N2) are short-circuited, a closed loop is formed, and an overcurrent (I2) flows through the battery module array (100).

[0046] Accordingly, as illustrated in FIG. 5, the current blocking element (112) included in each battery module (110) is melted and opened by the high current, thereby electrically separating each battery module (110) from each other. In this way, when a plurality of battery modules (110) of the battery module array (100) are electrically separated from each other before the battery module array (100) explodes on a large scale, the battery module array (100) changes to a low voltage state, and the explosion can be reduced compared to the case where it is in a high voltage state.

[0048] A person skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present 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 should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0050] 10: Battery pack 20: External device 100: Battery module array 110-1 ~ 110-6: 1st to 6th battery modules 111: Battery cell 112: Current blocking element 113: Sensor section 120: Manual Service Blocking Module 200: Battery disconnect unit 210 ~ 230: 1st to 3rd switch sections 221, 222: Switch elements 223: Resistor element 300: Battery Management System (BMS)

Claims

Claim 1 A battery pack comprising: a battery module array having first and second terminals, comprising a plurality of battery modules connected in series—each of which includes at least one battery cell, a current cutoff element connected in series with the battery cell and opening when an overcurrent is applied, and a sensor unit that measures state information of the battery cell and transmits the measured value—; a battery cutoff unit comprising a first switch unit connected in series with the first terminal, a second switch unit connected in series with the second terminal, and a third switch unit connecting a connection node between the first terminal and the first switch unit and a connection node between the second terminal and the second switch unit; and a battery management system that, when the measured value transmitted from the sensor unit exceeds a preset threshold value, turns on the third switch unit to short-circuit the first and second terminals to open the current cutoff element and turns off at least one of the first and second switch units. Claim 2 In claim 1, the sensor unit comprises a battery pack including at least one of a temperature sensor and a gas sensor. Claim 3 A battery pack according to claim 1, wherein the sensor unit includes a plurality of temperature sensors disposed in each of the plurality of battery modules, the measured value is a temperature information value of the battery cell, and the battery management system turns on the third switch unit if the measured value transmitted from at least one of the plurality of temperature sensors exceeds the threshold value transmitted from another temperature sensor, and the threshold value is 3℃. Claim 4 In claim 1, the sensor unit includes a temperature sensor and a gas sensor, and the battery management system turns on the third switch unit when the measured values ​​transmitted from the temperature sensor and the gas sensor, respectively, both exceed the threshold value. Claim 5 In claim 1, the battery cell is a lithium-ion battery cell, and the battery pack has a threshold value of 50℃. Claim 6 delete Claim 7 In claim 1, the plurality of battery modules each comprise a plurality of battery cells connected in series, forming a battery pack. Claim 8 In claim 1, the first to third switch portions are power relays in the battery pack. Claim 9 In claim 1, the current blocking element is a fuse in the battery pack. Claim 10 In claim 1, the battery pack further comprises a battery module array including a Manual Service Disconnector module connected in series with the plurality of battery modules.

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