Uninterruptible power supply and operating method thereof

Abstract

An uninterruptible power supply includes: a battery; an insertion node configured to be electrically connected to a first main power line of the connection device when the uninterruptible power supply is coupled to the connection device connected to the first main power line and the second main power line; a power switch configured to connect the connection device and the battery; and a battery management system configured to measure a first voltage of the first main power line through the connection device, turn on the power switch when the measured first voltage is below a predetermined threshold, measure a second voltage of the insertion node in an on state of the power switch, and transmit the measured second voltage to the connection device. And turning off the power switch when the measured second voltage is lower than the reference voltage.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0002] This application claims priority based on and claims the benefit of Korean Patent Application No. 10 - 2023 - 0062296, filed with the Korean Intellectual Property Office on May 15, 2023, and Korean Patent Application No. 10 - 2024 - 0052990, filed with the Korean Intellectual Property Office on April 19, 2024, the disclosures of which are incorporated herein by reference in their entirety.

[0003] The present disclosure relates to an uninterruptible power supply and an operation method thereof. Background Art

[0004] An uninterruptible power supply (UPS) supplies power to a power line during a power line interruption. However, even when the uninterruptible power supply is disconnected from the power line, the uninterruptible power supply may operate as if there is a power interruption. When the uninterruptible power supply is disconnected from the power line, the uninterruptible power supply may recognize the disconnected state as a power interruption and continue to supply power without stopping its operation. Summary of the Invention

[0005] Technical Problem

[0006] The present disclosure attempts to provide an uninterruptible power supply and an operation method thereof that can distinguish between a power line interruption and a disconnection from the power line.

[0007] Technical Solution

[0008] According to an embodiment of the present disclosure, an uninterruptible power supply includes: a battery; an insertion node configured to be electrically connected to a first main power line in a connection device when the uninterruptible power supply is coupled to the connection device connected to a first main power line and a second main power line; a power switch configured to connect the connection device and the battery; and a battery management system configured to measure a first voltage of the first main power line through the connection device, turn on the power switch when the measured first voltage is lower than a predetermined threshold, measure a second voltage of the insertion node in an on - state of the power switch, and turn off the power switch when the measured second voltage is lower than a reference voltage.

[0009] At a predetermined monitoring interval, the battery management system may measure the first voltage, compare the measured first voltage with the threshold, when the measured first voltage is equal to or higher than the threshold, determine that power is being supplied through the first main power line and the second main power line, and control the power switch to be turned off.

[0010] When the measured first voltage is lower than the threshold value, the battery management system can turn on the power switch, measure the second voltage in the on state of the power switch, turn off the power switch when the measured second voltage is lower than the reference voltage, and maintain the on state of the power switch when the measured second voltage is equal to or higher than the reference voltage.

[0011] When the measured second voltage is lower than the reference voltage, the battery management system can turn off the power switch, and then, the battery management system is turned off.

[0012] When the measured second voltage is equal to or higher than the reference voltage, the battery management system can maintain the on state of the power switch.

[0013] The connection device may include: a first connection terminal connected to the first main power line; a first wire located between the first main power line and the first connection terminal; a second connection terminal that is electrically connected to the insertion node when the uninterruptible power supply and the connection device are coupled.

[0014] When the measured second voltage is lower than the reference voltage in the on state of the power switch, the battery management system can turn off the power switch.

[0015] According to another embodiment of the present disclosure, a method for operating an uninterruptible power supply includes: setting the uninterruptible power supply to be electrically connected to a connection device that is connected to a first main power line and a second main power line; detecting a power-off state in which power is not supplied to the first main power line and the second main power line; when the power-off state is detected, turning on the power switch to connect the battery of the uninterruptible power supply to the connection device; after turning on the power switch, measuring a first voltage of the first main power line through an insertion node set to be connected to the first main power line; when the measured first voltage is lower than a predetermined reference value, determining that the uninterruptible power supply and the connection device are in a disconnected state; and turning off the power switch in the determined disconnected state.

[0016] The above method may further include: when the measured first voltage is equal to or greater than the predetermined reference value, determining that a power interruption state has occurred; and maintaining the on state of the power switch in the determined power interruption state.

[0017] The above method may further include: in the determined disconnected state, turning off the power switch, and then, turning off the uninterruptible power supply.

[0018] Advantageous Effects

[0019] The present disclosure provides an uninterruptible power supply and an operation method thereof, and the uninterruptible power supply can distinguish between a power line interruption and a disconnection from the power line. Description of the Drawings

[0020] Figure 1 is a view showing a power system to which an uninterruptible power supply according to an embodiment of the present disclosure is applied.

[0021] Figure 2 is a block diagram showing an uninterruptible power supply and a connection device in an idle mode.

[0022] Figure 3 is a block diagram showing an uninterruptible power supply and a connection device in a power supply mode.

[0023] Figure 4 is a block diagram showing an uninterruptible power supply and a connection device in a disconnect mode.

[0024] Figure 5 is a flowchart showing the operation of an uninterruptible power supply according to an embodiment.

[0025] Figure 6 is a block diagram showing a plurality of uninterruptible power supplies connected to a main power line according to another embodiment.

[0026] Figure 7 is a block diagram showing a hardware configuration for implementing a battery management system included in an uninterruptible power supply according to an embodiment. Detailed Description

[0027] When describing embodiments of the present disclosure, if the detailed description of related known technologies is determined to obscure the gist of the embodiments, the detailed description of related known technologies may be omitted. In addition, the drawings are only intended to facilitate the understanding of the embodiments described herein and do not limit the technical idea of the present disclosure, and should be construed as covering all modifications, equivalents, and alternatives included in the technical gist and scope of the present disclosure.

[0028] Terms having ordinal numbers such as first, second, etc. may be used to describe various components, but should not be construed as limiting the components. These terms are only used for the purpose of distinguishing components from other components.

[0029] When two components are "coupled" or "connected" to each other, this description should be understood to mean not only that the two components are directly coupled or connected to each other, but also that another component may be present between the two components. Meanwhile, when two components are "directly coupled" or "directly connected" to each other, this description should be understood to mean that there is no other component between the two components.

[0030] In the following description, terms such as "including" and "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, and combinations thereof described herein, but should not be construed as excluding the presence or possible addition of one or more other features, numbers, steps, operations, components, parts, and combinations thereof.

[0031] Figure 1 It is a view showing the power system to which the uninterruptible power supply according to an embodiment of the present disclosure is applied.

[0032] As Figure 1 shown, two main power lines 11 and 12 are connected between the power grid 10 and the electrical load 20. After filtering, switching, or converting the power, the power equipment 30 can supply the power supplied from the power grid 10 to the electrical load 20 through the two main power lines 11 and 12.

[0033] The uninterruptible power supply 100 can be connected to the two main power lines 11 and 12 via the connection device 200. The uninterruptible power supply 100 can operate as a power source or be charged by the power equipment 30. When the power from the power grid 10 is not supplied to the two main power lines 11 and 12 due to the occurrence of an abnormal state such as a power outage, the power supplied from the uninterruptible power supply 100 can be supplied to the two main power lines 11 and 12. Alternatively, the uninterruptible power supply 100 can be charged with the power from the power equipment 30 through the two main power lines 11 and 12 and the connection device 200.

[0034] The connection device 200 can implement the connection between the two main power lines 11 and 12 and the uninterruptible power supply 100. The connection device 200 can include wires and various circuit elements to achieve the electrical connection between the two main power lines 11 and 12 and the uninterruptible power supply 100. In Figure 1 it, the connection device 200 includes five connection terminals CT1 to CT5 for connecting to external components. Figure 1 The five connection terminals CT1 to CT5 shown in it are examples for describing an embodiment, and the present disclosure is not limited thereto. The connection terminal CT1 and the main power line 11 can be connected via the wire 31, and the connection terminals CT1 and CT4 can be connected via the wire 211. The connection terminal CT3 and the wire 211 can be connected via the wire 212. The connection terminal CT2 and the main power line 12 can be connected via the wire 32. The connection terminal CT4 can be connected to one end of the power switch 150 of the uninterruptible power supply 100, and the connection terminals CT2 and CT5 can be connected via the wire 213. The connection terminal CT5 can be connected to the anode (negative electrode) of the battery device 110 of the uninterruptible power supply 100. The anode of the battery device 110 can be the anode with the lowest potential among the anodes of the multiple battery cells included in the battery device 110. Although Figure 1The state where the connection terminal CT3 is connected to the wire 211 via the wire 212 is shown, but the present disclosure is not limited thereto. For example, the connection terminals CT1 and CT3 can be the same terminal. Alternatively, the connection terminal CT3 can be directly connected to the connection terminal CT1 via the wire 212. The connection terminal CT3 is a terminal for detecting the connection between the uninterruptible power supply 100 and the main power line 11, and can be implemented in various forms.

[0035] The uninterruptible power supply 100 can include an insertion node 121 that contacts the connection terminal CT3 when the uninterruptible power supply 100 is coupled to the connection device 200. One end of the insertion node 121 is connected to the battery management system (BMS) 120 of the uninterruptible power supply 100, and when the uninterruptible power supply 100 is coupled to the connection device 200, the other end of the insertion node 121 can contact the connection terminal CT3. This contact can be implemented as a physical coupling. In this way, the insertion node 121 can be electrically connected to the main power line 11 by being electrically connected to the connection terminal CT3. When the uninterruptible power supply 100 is disconnected from the connection device 200, the other end of the insertion node 121 can no longer contact the connection terminal CT3 and can become floating.

[0036] As described above, the uninterruptible power supply 100 can also include a battery device 110, a battery management system 120, and a power switch 150. The battery device 110 can include a plurality of battery cells 111. Although Figure 1 a plurality of battery cells 111 connected in series are shown, the present disclosure is not limited thereto. For example, the connection between the plurality of battery cells 111 can be implemented in various ways, including series connection, parallel connection, and combinations thereof. The other end of the power switch 150 can be connected to the cathode (positive electrode) of the battery cell having the highest potential among the plurality of battery cells 111. The uninterruptible power supply 100 can supply power in the on state of the power switch 150.

[0037] The battery management system 120 can be connected to the battery device 110 to monitor the battery device 110 and control charging, discharging, and other protection operations. The battery management system 120 can perform various operations required to manage the battery device 110, including, for example, measuring the cell voltage of each of the plurality of battery cells 111, measuring the current flowing in the battery device 110, measuring the temperature of the battery device 110, and estimating the SOC (state of charge) and SOH (state of health) of the battery device 110.

[0038] The battery management system 120 can generate a switching signal SWC for controlling the switching operation of the power switch 150 connected between the uninterruptible power supply 100 and the connection device 200. One end of the power switch 150 is connected to the connection terminal CT4 of the connection device 200.

[0039] The battery management system 120 can detect the voltage of the main power line 11. To this end, the battery management system 120 can measure the voltage VS1 at one end of the power switch 150 electrically connected to the connection terminal CT4. When the voltage at one end of the power switch 150 electrically connected to the connection terminal CT4 is equal to or higher than a predetermined value, the battery management system 120 can determine that voltage is being supplied to the connection device 200, and when the voltage at one end of the power switch 150 is lower than the predetermined value, the battery management system 120 can determine that no voltage is being supplied to the connection device 200. When no voltage is supplied to the connection device 200, the battery management system 120 can turn on the power switch 150 to determine which of the power interruption state and the disconnection state has occurred, and detect the voltage of the main power line 11 through the insertion node 121. At the same time, the battery management system 120 can also measure the voltage VS2 at the other end of the power switch 150. When the difference between the voltages VS1 and VS2 is equal to or higher than a predetermined value, the battery management system 120 can determine that voltage is being supplied to the connection device 200, and when the difference is lower than the predetermined value, the battery management system 120 can determine that no voltage is being supplied to the connection device 200.

[0040] The power interruption state can indicate a state in which the power supply from the power grid 10 is cut off, and the disconnection state can indicate a state in which the uninterruptible power supply 100 is disconnected or separated from the connection device 200. In the power interruption state, the uninterruptible power supply 100 is connected to the connection device 200, but since no voltage is supplied from the main power line 11 to the connection device 200, it may not be possible to detect the voltage of the main power line 11 through the connection device 200. In the disconnection state, since the uninterruptible power supply 100 is disconnected from the connection device 200, the uninterruptible power supply 100 may not be able to detect the voltage of the main power line 11 through the connection device 200. That is, in both the disconnection state and the power interruption state, the uninterruptible power supply 100 may not be able to detect the voltage of the main power line 11. To determine the operation mode of the uninterruptible power supply 100, it is necessary to determine which of the disconnection state and the power interruption state has occurred. The battery management system 120 according to an embodiment can measure the voltage of the main power line 11 through the insertion node 121, and determine which of the power interruption state or the disconnection state has occurred based on the measured voltage. When the voltage of the main power line 11 is not detected through the connection device 200, the battery management system 120 can turn on the power switch 150, and when the voltage of the main power line 11 is detected through the insertion node 121 during the on period of the power switch 150, the battery management system 120 can determine that the power interruption state has occurred. When the voltage of the main power line 11 is not detected through the insertion node 121 during the on period of the power switch 150, the battery management system 120 can determine that the disconnection state has occurred.

[0041] The operating modes of the uninterruptible power supply 100 may include an idle mode, a power supply mode, and a disconnect mode.

[0042] The idle mode of the uninterruptible power supply 100 refers to an operating mode when power from the power grid 10 is supplied to the power load 20 through the power device 30 and the two main power lines 11 and 12 in a state where the uninterruptible power supply 100 is capable of supplying power (hereinafter referred to as the "on state"). In the idle mode, the uninterruptible power supply 100 may detect the voltage of at least one of the two main power lines 11 and 12 at a predetermined monitoring interval (e.g., several milliseconds) through the connection device 200. For example, the battery management system 120 may detect the voltage of the main power line 11 based on the voltage at one end of the power switch 150 (the end connected to the connection terminal CT4) or the difference between the voltages at both ends of the power switch 150. The main power line 11 is electrically connected to the connection terminal CT4 via the connection device 200, and a voltage may appear in the main power line 11 when power from the power grid 10 is supplied to the electrical load 20 through the power device 30 and the two main power lines 11 and 12. In this way, in the idle mode, the battery management system 120 can monitor whether power is supplied through the two main power lines 11 and 12, thereby detecting a power interruption or disconnection.

[0043] The power supply mode may refer to an operating mode in which the uninterruptible power supply 100 supplies power. In the power supply mode, the power switch 150 is in the on state. When it is detected in the idle mode that no power is supplied through the two main power lines 11 and 12, the battery management system 120 may turn on the power switch 150. After the power switch 150 is turned on, the battery management system 120 may determine which one of the power interruption state and the disconnection state has occurred. When the battery management system 120 determines that the power interruption state has occurred, the power switch 150 remains in the on state. In the on state of the power switch 150, the connection device 200 may supply power from the uninterruptible power supply 100 to the electrical load 20 through the two main power lines 11 and 12. In this way, the power supply mode is a mode in which the uninterruptible power supply 100 operates as a power source during the on period of the power switch 150.

[0044] When the battery management system 120 determines that the disconnection state has occurred, the battery management system 120 may turn off the power switch 150. The disconnect mode may be an operating mode of the uninterruptible power supply 100 in a state separated from the connection device 200. In the disconnect mode, the battery management system 120 is turned off, and the uninterruptible power supply 100 may also stop its operation, i.e., be turned off.

[0045] Figure 2 It is a block diagram showing the uninterruptible power supply and the connection device in the idle mode.

[0046] As shown Figure 2 in the figure, the power switch 150 is in the off state during the idle mode. The anode of the battery device 110 is connected to the connection terminal CT5 of the connection device 200 via the wire 140, and the insertion node 121 is connected to the connection terminal CT3 of the connection device 200. The battery management system 120 can measure the voltage of the main power line 11 through the connection device 200 at a monitoring interval. The battery management system 120 can measure either the voltage VS1 or both the voltages VS1 and VS2, and when the voltage of the main power line 11 is equal to or higher than a predetermined threshold, the battery management system 120 can determine that neither a power interruption state nor a disconnection state has occurred, and remain in the idle mode. When the measured voltage of the main power line 11 is lower than the predetermined threshold, the battery management system 120 can perform a state identification operation to determine which one of the power interruption state and the disconnection state has occurred.

[0047] Figure 3 is a block diagram showing an uninterruptible power supply and a connection device in a power supply mode.

[0048] As a result of the state identification operation, when a power interruption state occurs, the uninterruptible power supply 100 can operate in the power supply mode. In the power supply mode, the power switch 150 is in the on state. The cathode of the battery device 110 is electrically connected to the main power line 11, and the anode of the battery device 110 is electrically connected to the main power line 12, so that the power of the battery device 110 can be supplied to both the main power lines 11 and 12.

[0049] Figure 4 is a block diagram showing an uninterruptible power supply and a connection device in a disconnection mode.

[0050] As a result of the state identification operation, when a disconnection state occurs, the uninterruptible power supply 100 can operate in the disconnection mode. In the disconnection mode, the battery management system 120 can disconnect the power switch 150 and can be turned off.

[0051] Figure 5 is a flowchart showing the operation of an uninterruptible power supply according to an embodiment.

[0052] First, in S310, the battery management system 120 can monitor the voltages of the main power lines 11 and 12 in the idle mode through the connection device 200. In S320, the battery management system 120 can determine whether the monitored voltage is equal to or higher than the threshold. When it is determined in S320 that the monitored voltage is equal to or higher than the threshold (S320, Yes), the battery management system 120 can return to S310 to monitor the voltages of the main power lines 11 and 12 in the idle mode.

[0053] Meanwhile, when it is determined in S320 that the monitored voltage is lower than the threshold (S320, No), for example, when no voltage is detected in the main power lines 11 and 12, the battery management system 120 may turn on the power switch 150 to identify the power interruption state or the disconnection state.

[0054] Then, in S340, the battery management system 120 may measure the voltages of the main power lines 11 and 12 through the insertion node 121. Subsequently, in S350, the battery management system 120 may determine whether the measured voltage is equal to or higher than a predetermined reference value.

[0055] When it is determined in S350 that the measured voltage is equal to or higher than the predetermined reference value (S350, Yes), the battery management system 120 may operate in the power supply mode in S360, supply power to the main power lines 11 and 12, and at the same time continue to maintain the on state of the power switch 150 as described above.

[0056] Meanwhile, when it is determined in S350 that the measured voltage is lower than the predetermined reference value (S350, No), the battery management system 120 may operate in the disconnection mode and stop supplying power to the main power lines 11 and 12 by turning off the power switch 150 as described above. In the disconnection mode, the uninterruptible power supply 100 may also be turned off simultaneously with the turn-off of the battery management system 120.

[0057] In another embodiment, multiple uninterruptible power supplies may be connected to the two main power lines 11 and 12.

[0058] Figure 6 FIG. is a block diagram showing multiple uninterruptible power supplies connected to the main power lines according to another embodiment.

[0059] Although Figure 6 FIG. shows three uninterruptible power supplies connected to the two main power lines 11 and 12, the present disclosure is not limited thereto.

[0060] The configuration of each of the three connection devices 200_1, 200_2, and 200_3 and the three uninterruptible power supplies 100_1, 100_2, and 100_3 may be the same as the configuration shown in Figure 1 Hereinafter, the description of the embodiment shown in Figure 6 will be described by omitting the description that is the same as the above description.

[0061] The three uninterruptible power supplies 100_1, 100_2, and 100_3 may respectively include battery devices 110_1, 110_2, and 110_3, battery management systems 110_1, 110_2, and 110_3, power switches 150_1, 150_2, and 150_3, and insertion nodes 160_1, 160_2, and 160_3.

[0062] The connection device 200_1 can be connected to two main power lines 11 and 12 via two wires 31_1 and 32_1, the connection device 200_2 can be connected to two main power lines 11 and 12 via two wires 31_2 and 32_2, and the connection device 200_3 can be connected to two main power lines 11 and 12 via two wires 31_3 and 32_3.

[0063] The battery management systems 120_1, 120_2, and 120_3 of the three uninterruptible power supplies 100_1, 100_2, and 100_3 can measure the voltage of the main power line 11 at monitoring intervals in the on state of the uninterruptible power supplies 100_1, 100_2, and 100_3, and operate according to the idle mode when the measured voltage is equal to or higher than the threshold. The three battery management systems 110_1, 110_2, and 110_3 can perform the monitoring operation independently.

[0064] As a result of the monitoring, when the measured voltage of the main power line 11 is lower than the threshold, the battery management systems 110_1, 110_2, and 110_3 can turn on the power switches 150_1, 150_2, and 150_3, measure the voltage of the main power line 11 through the insertion nodes 160_1, 160_2, and 160_3, determine that a power interruption state has occurred when the measured voltage is equal to or higher than the reference voltage, and determine that a disconnection state has occurred when the measured voltage is lower than the reference voltage. Each of the three battery management systems 120_1, 120_2, and 120_3 can perform the state determination operation independently.

[0065] The three battery management systems 120_1, 120_2, and 120_3 can operate according to the power supply mode when a power interruption state occurs and operate according to the disconnection mode when a disconnection state occurs, independently.

[0066] Figure 7 is a block diagram showing the hardware configuration of the battery management system 120 included in the uninterruptible power supply 100 according to an embodiment.

[0067] The battery management system 120 according to an embodiment of the present disclosure may include an MCU 123, a memory 125, and a communication I / F 127. The MCU 123 may refer to a micro control unit and is a processor that executes various programs stored in the memory 125, processes various data for the programs, and executes the functions of the battery management system 120.

[0068] The memory 125 can store various programs and data related to the operation of the battery management system 120 for implementing the operation of the uninterruptible power supply 100. A plurality of memories 125 may be provided as needed. The memory 125 can be a volatile or non-volatile memory. For a volatile memory, the memory 125 can be, for example, RAM, DRAM, or SRAM. For a non-volatile memory, the memory 125 can be, for example, ROM, PROM, EAROM, EPROM, EEPROM, or flash memory. The examples of the memory 125 are merely examples and are not limited thereto.

[0069] The communication I / F 127 is configured to send various data to and receive various data from a server, and can be any of various devices capable of supporting wired or wireless communication. For example, through the communication I / F 127, various programs or data for implementing the operation of the uninterruptible power supply 100 can be sent to and received from a separate external server through wired communication or wireless communication.

[0070] As described above, the uninterruptible power supply according to the present disclosure can identify a power interruption state and a disconnection state without the need for a separate device, which may not cause unnecessary operations. Since a conventional uninterruptible power supply remains in an on state even in a disconnected state, the battery management system needs to perform a protection operation to detect an abnormality such as a short circuit in the battery device, and the operation of the battery management system can consume power. The uninterruptible power supply according to the present disclosure can eliminate such unnecessary operations, and thus, not only prevent safety accidents caused by an abnormality of the battery device, but also prevent deterioration of the performance and lifespan of the battery device.

[0071] From the foregoing, it will be appreciated that the various embodiments of the present disclosure have been described for purposes of illustration, and various modifications can be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, where the true scope and spirit are indicated by the appended claims.

Claims

1. An uninterruptible power supply, comprising: a battery; an insertion node configured to be electrically connected to the first main power line in a connection device when the uninterruptible power supply is coupled to the connection device connected to a first main power line and a second main power line; a power switch configured to connect the connection device and the battery; and a battery management system configured to measure a first voltage of the first main power line through the connection device, turn on the power switch when the measured first voltage is lower than a predetermined threshold, measure a second voltage of the insertion node in an on state of the power switch, and turn off the power switch when the measured second voltage is lower than a reference voltage.

2. The uninterruptible power supply according to claim 1, wherein, At a predetermined monitoring interval, the battery management system measures the first voltage, compares the measured first voltage with the threshold, when the measured first voltage is equal to or higher than the threshold, determines that power is being supplied through the first main power line and the second main power line, and controls the power switch to be turned off.

3. The uninterruptible power supply according to claim 2, wherein, When the measured first voltage is lower than the threshold, the battery management system turns on the power switch, measures the second voltage in the on state of the power switch, turns off the power switch when the measured second voltage is lower than the reference voltage, and maintains the on state of the power switch when the measured second voltage is equal to or higher than the reference voltage.

4. The uninterruptible power supply according to claim 2, wherein, When the measured second voltage is lower than the reference voltage, the battery management system turns off the power switch, and then, the battery management system is turned off.

5. The uninterruptible power supply according to claim 1, wherein, When the measured second voltage is equal to or higher than the reference voltage, the battery management system maintains the on state of the power switch.

6. The uninterruptible power supply according to claim 1, wherein, The connection device includes: a first connection terminal connected to the first main power line; a first wire located between the first main power line and the first connection terminal; a second connection terminal electrically connected to the insertion node when the uninterruptible power supply and the connection device are coupled.

7. The uninterruptible power supply according to claim 1, wherein, When the second voltage measured in the on state of the power switch is lower than the reference voltage, the battery management system turns off the power switch.

8. A method for operating an uninterruptible power supply, the method comprising: setting the uninterruptible power supply to be electrically connected to a connection device connected to a first main power line and a second main power line; detecting a power-off state in which power is not supplied to the first main power line and the second main power line; when the power-off state is detected, turning on a power switch to connect a battery of the uninterruptible power supply to the connection device; after turning on the power switch, measuring a first voltage of the first main power line through an insertion node set to be connected to the first main power line; when the measured first voltage is lower than a predetermined reference value, determining that the uninterruptible power supply and the connection device are in a disconnected state; and turning off the power switch in the determined disconnected state.

9. The method according to claim 8 further comprises: When the measured first voltage is equal to or greater than the predetermined reference value, determining that a power interruption state has occurred; And Maintaining the on state of the power switch in the determined power interruption state.

10. The method according to claim 8 further comprises: In the determined off state, turning off the power switch, and then turning off the uninterruptible power supply.

11. A non-transitory computer-readable storage medium storing a program for implementing a method for operating an uninterruptible power supply by executing a process including the following steps: Setting the uninterruptible power supply to be electrically connected to a connection device that is connected to a first main power line and a second main power line; Detecting a power-off state in which power is not supplied to the first main power line and the second main power line; When the power-off state is detected, turning on a power switch to connect a battery of the uninterruptible power supply to the connection device; After turning on the power switch, measuring a first voltage of the first main power line through an insertion node set to be connected to the first main power line; When the measured first voltage is lower than a predetermined reference value, determining that the uninterruptible power supply and the connection device are in a disconnected state; And Turning off the power switch in the determined disconnected state.

12. The non-transitory computer-readable storage medium according to claim 11 further comprises: In the determined disconnected state, turning off the power switch, and then turning off the uninterruptible power supply.

13. The non-transitory computer-readable storage medium according to claim 11 further comprises: When the measured first voltage is equal to or greater than the predetermined reference value, determining that a power-off state has occurred; And Maintaining the on state of the power switch in the determined power-off state.

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