JP5361594B2 - Lithium ion secondary battery system and power supply method to management device - Google Patents

Description

  The present invention relates to a lithium ion secondary battery system including a management device that monitors a lithium ion secondary battery and a method for supplying power to the management device.

  For example, a management device is known that monitors and analyzes the state of each lead storage battery and the state of the entire assembled battery with respect to the assembled battery in which a plurality of lead storage batteries (cells) are connected (see, for example, Patent Document 1). In recent years, lithium ion secondary batteries having advantages such as higher energy density and less self-discharge than lead storage batteries have been widely used as storage batteries for automobiles and storage batteries for electric and electronic devices. . For such lead-acid batteries and lithium-ion secondary batteries, a discharge end voltage is specified and set according to the characteristics, capacity, and discharge current, and the discharge should be terminated. By terminating the operation, overdischarge of the battery can be prevented and the battery can be operated properly.

JP 2000-048861 A

  By the way, it is desirable to supply power from the battery to the management apparatus in order to ensure the power supply of the management apparatus as described above at the time of a power failure in which power supply from the commercial power supply stops. However, when it takes a long time to restore commercial power due to a disaster such as an earthquake, or when the management device cannot be stopped by visiting the installation location of the management device, power is supplied from the battery to the management device for a long time. It is assumed that In such a case, the battery voltage exceeds the discharge end voltage, and the battery is discharged to a lower voltage. That is, there are cases where the battery is overdischarged, and even if recovery charging is performed thereafter, the battery recovers and is not charged.

  In particular, in a lithium ion secondary battery, if the battery is over-discharged to a certain voltage, cobalt from the positive electrode or copper from the current collector of the cathode (negative electrode) will elute and function as a secondary battery. Further, there is a risk of abnormal heat generation. For this reason, when power is supplied from the battery to the management device, it is necessary to properly regulate and control when power is supplied from the battery to the management device and to what extent the battery is discharged, especially in lithium ion secondary batteries. Applicants have come to think of that.

  Accordingly, the present invention provides a power supply to a lithium ion secondary battery system and a management device that can appropriately prevent a problem due to overdischarge of the lithium ion secondary battery while securing the power supply of the management device in the event of a power failure, etc. It aims to provide a method.

In order to achieve the above object, the invention according to claim 1 is a lithium ion secondary battery that discharges and supplies power to load equipment, and adjusts at least a charging voltage of the lithium ion secondary battery and changes a cell state. A cell controller for monitoring, a battery pack management unit for monitoring a state of a battery pack configured by connecting a plurality of the lithium ion batteries in series by receiving from the cell controller, a cell state from the battery pack management unit, a lithium ion secondary battery system including a monitoring device, the accumulating data including assembled battery state, when at least the lithium ion secondary battery to supply power to the load equipment, the lithium ion secondary supplying power from the battery to the monitoring device and the battery pack management unit and the cell controller, the lithium-ion When the voltage of the next battery is lower than a first protection voltage set lower than the discharge end voltage, the power supply to the monitoring device from the lithium-ion secondary battery is stopped, the lithium ion secondary battery If the voltage of the reaches the second guard voltage is a minimum voltage necessary for protecting the lithium ion secondary battery lower than the discharge end voltage and the first guard voltage, the lithium ion The lithium ion secondary battery and the management device are connected so that power supply from the secondary battery to the cell controller and the assembled battery management unit is stopped.

  According to the present invention, when power is supplied from the lithium ion secondary battery to the load facility, power is also supplied from the lithium ion secondary battery to the management device, and the voltage of the lithium ion secondary battery is changed to the discharge end voltage. When it reaches, the power supply to the load facility is stopped, while the power supply to the management device is continued. Furthermore, when the voltage of the lithium ion secondary battery reaches the protection voltage, power supply to the management device is stopped.

  According to a second aspect of the present invention, in the lithium ion secondary battery system according to the first aspect, the lithium ion secondary battery is float-charged, and when the lithium ion secondary battery is float charged, float charging is performed. The charging source and the management device are connected so that power is supplied from the charging source to the management device.

  According to the present invention, at the time of float charging of the lithium ion secondary battery, power is supplied from the charging source of the float charging to the lithium ion secondary battery and the management device, and power is supplied from the lithium ion secondary battery to the load facility. In this case, power is supplied from the lithium ion secondary battery to the management device.

According to a third aspect of the present invention, there is provided a cell controller that adjusts at least a charging voltage of a lithium ion secondary battery that discharges and supplies power to load equipment and monitors a cell state, and a plurality of the lithium ion batteries are connected in series. It includes a assembled battery management unit that monitors the reception from the cell controller a state constructed battery pack being, and a monitoring device for storing data including the cell state and the assembled battery status from the battery pack management unit A method of supplying power to a management device, wherein at least when the lithium ion secondary battery supplies power to the load facility, the cell controller, the assembled battery management unit, and the monitoring from the lithium ion secondary battery device supplies power to, the first protection by the voltage of the lithium ion secondary battery is set lower than the discharge end voltage When lower than pressure, the power supply to the monitoring device stops, wherein the lower than the voltage of the lithium ion secondary battery wherein discharge cutoff voltage and the first guard voltage from the lithium-ion secondary battery When the second protection voltage, which is the minimum voltage necessary to protect the lithium ion secondary battery, is reached, power is supplied from the lithium ion secondary battery to the cell controller and the assembled battery management unit . It is characterized by stopping.

  According to the first and third aspects of the invention, when power is supplied from the lithium ion secondary battery to the load facility due to a power failure of the commercial power supply, the power is also supplied from the lithium ion secondary battery to the management device. Therefore, the power supply of the management device can be secured. Even if the voltage of the lithium ion secondary battery reaches the discharge end voltage and the power supply to the load facility is stopped, the power supply to the management device is continued. Monitoring of the ion secondary battery can be continued. In addition, when the voltage of the lithium ion secondary battery reaches the protection voltage, the power supply to the management device is stopped, so that it is possible to appropriately and reliably prevent problems due to overdischarge of the lithium ion secondary battery. .

  According to the second aspect of the present invention, when the lithium ion secondary battery is float-charged, power is supplied from the charge source of the float charge to the management device without consuming the capacity of the lithium-ion secondary battery, The power supply of the management device can be secured.

It is a schematic block diagram which shows the state which applied the lithium ion secondary battery system which concerns on embodiment of this invention to the rectifier. It is a schematic block diagram which shows the cell controller of the system of FIG. It is a schematic block diagram which shows the assembled battery management unit of the system of FIG. It is a flowchart which shows the process at the time of discharge of the system of FIG. 1, and an effect | action. 5 is a flowchart showing a continuation of FIG.

  The present invention will be described below based on the illustrated embodiments.

  FIG. 1 is a schematic configuration diagram showing a state in which a lithium ion secondary battery system 1 according to an embodiment of the present invention is applied to a rectifier. In this lithium ion secondary battery system 1, a plurality of lithium ion cells (lithium ion secondary batteries) 2, which are unit cells that discharge and supply power to the load equipment 102, are connected in series to form a battery pack 3. A management device for monitoring and managing the assembled battery 3 is provided. Here, the assembled battery 3 is used and operated by float charging, and is always in a charged state during normal times.

  The management device mainly includes a cell controller 4, an assembled battery management unit 5, and a monitoring device 6. Moreover, in this embodiment, about 6 to 13 lithium ion cells 2 are connected in series to form an assembled battery 3, and such assembled battery 3 includes a charge switch 71 and a discharge switch connected in parallel. 72 is connected between the AC / DC converter 101 and the load facility 102.

  The cell controller 4 measures and monitors the cell state such as the voltage and temperature of each lithium ion cell 2 and adjusts the charging voltage of each lithium ion cell 2 to be within a predetermined value. Specifically, as shown in FIG. 2, a measurement adjustment unit 41 disposed in each lithium ion cell 2 and a module management unit 42 that is communicably connected to each measurement adjustment unit 41 are provided. The measurement adjusting unit 41 bypasses the charging current with a measuring unit that measures the voltage (voltage during charging, voltage during discharging) and temperature of the lithium ion cell 2, a bypass current flowing through a bypass circuit unit described later, and the like. A bypass circuit section for discharging the lithium ion cell 2. When the charging voltage of the lithium ion cell 2 measured by the measuring unit is higher than a predetermined voltage, the bypass circuit unit performs charging current bypassing and cell 2 discharging to lower the voltage, and the charging voltage is predetermined. It is designed to adjust within the voltage. Further, the module management unit 42 controls each measurement adjustment unit 41 and transmits the cell state such as voltage and temperature of the lithium ion cell 2 measured by each measurement adjustment unit 41 to the assembled battery management unit 5 in real time. It has a function to do.

  The assembled battery management unit 5 analyzes the cell state received from the cell controller 4, and monitors and analyzes the assembled battery state such as the charging current, discharging current, and total voltage of the assembled battery 3. Specifically, as shown in FIG. 3, mainly, a measuring instrument group 51, a communication unit 52, an input unit 53, an alarm unit 54, a control unit 55, and a central processing unit 56 that controls these, It has.

  The measuring instrument group 51 includes instruments such as an ammeter that measures the charging current and discharging current of the assembled battery 3 and a voltmeter that measures the total voltage (voltage during charging and discharging) of the assembled battery 3. ing. The communication unit 52 is a communication interface for performing data communication with the cell controller 4 and the monitoring device 6. The communication unit 52 receives a cell state and the like from the cell controller 4, and transmits a cell state and an assembled battery state to the monitoring device 6. It is something to do. The input unit 53 is a judgment reference value (threshold value) for analyzing and processing in the central processing unit 56 as described later, specifically, the specification capacity and allowable temperature of the lithium ion cell 2 and the allowable value of the assembled battery 3 The maximum discharge current Id, protection voltages VL2 and VL3 described later, and the like are input and set. These values may be set and input in advance.

  The alarm unit 54 issues an alarm when the central processing unit 56 determines that the abnormality of the lithium ion cell 2 or the entire assembled battery 3 is abnormal, and includes an LED lamp and an alarm buzzer. Further, when the lithium ion cell 2 is abnormal, the corresponding lithium ion cell 2 is displayed. The control unit 55 transmits a control signal (open / close signal) to the charge switch 71, the discharge switch 72, and the like based on analysis / processing results described later by the central processing unit 56.

  The central processing unit 56 controls the alarm unit 54 and controls the control unit 55 (switches 71, 72, 81, 82) based on the cell state received from the cell controller 4, the assembled battery state measured by the measuring instrument group 51, and the like. ) And command transmission to the cell controller 4 and the like. Specifically, processing is performed so that the lithium ion secondary battery system 1 operates and operates as described later and power is supplied to a management device described later.

  The charging switch 71 is a switch for connecting / disconnecting the battery pack 3 to / from the charging source for float charging the battery pack 3. That is, as shown in FIG. 1, the electric power from the commercial power source 100 is converted into direct current by the AC / DC converter 101 and supplied to the assembled battery 3 via the charging switch 71. The charging switch 71 is normally in an on (connected) state.

  The discharge switch 72 is a switch for connecting and disconnecting the load facility 102 to which the electric power is supplied from the assembled battery 3 and the assembled battery 3. That is, power from the assembled battery 3 is supplied to the load facility 102 via the discharge switch 72. The discharge switch 72 includes a switch body 721 and a diode 722 connected in series. The diode 722 has a function of allowing only a current flow from the assembled battery 3. In the normal state, the switch main body 721 is in an ON state, and discharge from the assembled battery 3 is always possible, so that power is not supplied to the assembled battery 3 via the discharge switch 72.

  The charge switch 71 and the discharge switch 72 are controlled by the assembled battery management unit 5. That is, as described above, when the control signal is transmitted from the control unit 55 based on the analysis / processing result by the central processing unit 56 of the assembled battery management unit 5, the charge switch 71 and the discharge switch 72 are opened and closed in response to the control signal. To do.

  The monitoring device 6 is a device that receives and collects the cell state and the assembled battery state from the assembled battery management unit 5 and the analysis / processing results by the central processing unit 56 and accumulates these data. In addition, the monitoring device 6 has a function of outputting (displaying, printing, etc.) or summing up accumulated data. Furthermore, the monitoring device 6 has a function of transferring data to a remote monitoring center or the like using a LAN line, a public line, or the like.

  When the assembled battery 3 is float charged, the cell controller 4, the assembled battery management unit 5, and the monitoring device 6 as described above are supplied with power from a charging source for float charging, and the assembled battery 3 supplies power to the load facility 102. When the battery is supplied, power is supplied from the assembled battery 3. That is, a DC / DC converter 8 is connected in parallel with the assembled battery 3, and a cell controller 4, an assembled battery management unit 5, and a monitoring device 6 are connected in parallel to the DC / DC converter 8. The DC / DC converter 8 is a converter that adjusts DC power from the AC / DC converter 101 and the assembled battery 3 to DC power suitable for the cell controller 4 and the like. The cell controller 4 and the assembled battery management unit 5 are the first ones. The monitoring device 6 is connected via a first switch 81 and a second switch 82. Then, as will be described later, the switches 81 and 82 are opened and closed by the central processing unit 56, so that power is supplied from the commercial power source 100 during float charging, and power is supplied from the assembled battery 3 during power failure.

  Next, the operation and operation of the lithium ion secondary battery system 1 having such a configuration and a method of supplying power to the management device will be described.

  First, at the time of float charging of the assembled battery 3, the charge switch 71, the discharge switch 72, the first switch 81, and the second switch 82 are all in an on (closed) state, and power is supplied from the commercial power source 100. The battery pack 3 is supplied via the AC / DC converter 101 and the charging switch 71. At the same time, power is supplied from the commercial power source 100 to the cell controller 4 and the assembled battery management unit 5 via the AC / DC converter 101, the charging switch 71, the DC / DC converter 8, and the first switch 81, and the second It is supplied to the monitoring device 6 via the switch 82. In addition, power from the commercial power supply 100 is supplied to the load facility 102 via the AC / DC converter 101.

  Next, when the power supply from the commercial power supply 100 stops (power failure), the assembled battery 3 starts discharging, and power is supplied from the assembled battery 3 to the load facility 102 via the discharge switch 72. At the same time, power is supplied from the assembled battery 3 to the cell controller 4 and the assembled battery management unit 5 via the DC / DC converter 8 and the first switch 81, and further to the monitoring device 6 via the second switch 82. Is supplied.

  In such a discharge mode, as shown in FIGS. 4 and 5, first, the central processing unit 56 of the assembled battery management unit 5 determines whether or not the charging current is zero or more (step S1). Is zero, that is, when the commercial power supply 100 is recovered and power is supplied to the assembled battery 3, the charging mode is entered, and the above-described float charging is performed. On the other hand, when the charging current is not zero or more, that is, when discharging is continuing, it is determined whether or not the following three requirements are satisfied. That is, whether the temperature of all the lithium ion cells 2 is lower than the upper limit temperature Th ° C. (step S2), whether the discharge current is lower than the allowable maximum discharge current Id (step S3), and the voltage of each cell 2 is the discharge end voltage. It is determined whether it is VL1 or more (step S4).

  Here, the upper limit temperature Th ° C. is the upper limit temperature at which the cell 2 can be safely used and operated, and the allowable maximum discharge current Id is the maximum discharge current that can be allowed according to the characteristics of the cell 2 and the specified capacity. is there. Further, the discharge end voltage VL1 is a voltage on the specification at which power supply to the load facility 102 should be stopped, and is set by the specification capacity of the lithium ion cell 2, the discharge current, and the like. And when satisfy | filling these requirements (in the case of "Y" in step S2-S4), it returns to step S1 and repeats the same process.

  On the other hand, when any of the requirements is not satisfied (in the case of “N” in any of Steps S2 to S4), for example, when the voltage of any of the cells 2 is lower than the end-of-discharge voltage VL1, the central processing unit 56 An alarm is generated from the alarm unit 54, and the switch body 721 of the discharge switch 72 is turned off (opened). At the same time, the charging switch 71 is turned off, and the power supply to the load facility 102 is stopped (step S5).

  In this state, power supply from the assembled battery 3 to the cell controller 4, the assembled battery management unit 5, and the monitoring device 6 is continued. When the voltage of any one of the cells 2 becomes lower than the first protection voltage VL2 (in the case of “N” in Step S6), the second switch 82 is turned off by the central processing unit 56, and monitoring is performed. The power supply to the device 6 is stopped (step S7). Thereafter, power supply from the assembled battery 3 to the cell controller 4 and the assembled battery management unit 5 is continued. When the voltage of any cell 2 becomes lower than the second protection voltage VL3 (in the case of “N” in step S8), the first switch 81 is turned off by the central processing unit 56, and the cell The power supply to the controller 4 and the assembled battery management unit 5 is stopped (step S9).

  Here, the protection voltages VL2 and VL3 are lower than the end-of-discharge voltage VL1, and the second protection voltage VL3 is a minimum voltage necessary to protect the lithium ion cell 2, and the characteristics of the lithium ion cell 2 It is set according to the ambient temperature. That is, when the voltage (open circuit voltage) of the lithium ion cell 2 is lower than the second protection voltage VL3, there is a possibility that the cell 2 is not charged even if recovery charging is performed, or a problem such as abnormal heat generation occurs. The second protection voltage VL3 is set to such a voltage threshold. The first protection voltage VL2 is set to an intermediate value between the discharge end voltage VL1 and the second protection voltage VL3. Thus, two protection voltages VL2 and VL3 are provided, and when the voltage of any one of the cells 2 falls below the first protection voltage VL2, only the power supply to the monitoring device 6 is stopped. This is because the controller 4 and the assembled battery management unit 5 are important devices for monitoring the assembled battery 3 and safely operating and controlling it, so it is desirable to continue the activation for as long as possible.

  By the way, since the lithium ion cell 2 has a very small self-discharge amount, when the discharge is finished, the open-circuit voltage does not drop greatly even if it is left for a long time thereafter, so that the discharge is stopped at the second protective voltage VL3. If this is the case, there will be fewer problems due to the voltage drop. For this reason, in consideration of safety, there is little need to set the second protection voltage VL3 to a voltage higher than the minimum voltage necessary for protecting the cell 2, but depending on the surrounding environment, etc. A high voltage may be set.

  Such processing is performed every time charging / discharging, and simultaneously, the cell state, the assembled battery state, the analysis / processing result, etc. are sequentially transmitted from the assembled battery management unit 5 to the monitoring device 6. These data are accumulated and aggregated. Then, by analyzing the accumulated data, the entire secondary battery system 1 can be operated more safely and appropriately.

  As described above, according to the method of supplying power to the lithium ion secondary battery system 1 and the management device, when the assembled battery 3 is float-charged, that is, when there is no power failure of the commercial power source 100, the commercial power source 100 Power is supplied to the management device. For this reason, the power supply of the management apparatus can be secured without consuming the capacity of the assembled battery 3. On the other hand, when the commercial power supply 100 fails, power is supplied from the assembled battery 3 to the load facility 102 and power is also supplied from the assembled battery 3 to the management device. be able to.

  Even if the voltage of the assembled battery 3 reaches the final discharge voltage VL1 and the power supply to the load facility 102 is stopped, the power supply to the management device is continued. Management such as monitoring and control of the battery 3 and each cell 2 can be continued. Furthermore, when the voltage of any cell 2 becomes lower than the second protection voltage VL3, the power supply to the entire management device is stopped, so that a malfunction due to overdischarge of the lithium ion cell 2 is prevented appropriately and reliably. It becomes possible.

  Here, as a case where the discharge from the assembled battery 3 continues, a disaster such as an earthquake is assumed. That is, since it takes a long time to restore the commercial power supply 100 in the event of a disaster, the assembled battery 3 continues to be unrecovered and charged, and an operator visits the place where the assembled battery 3 or the management apparatus is installed, The situation that cannot be stopped continues. For this reason, it is assumed that power is continuously supplied from the assembled battery 3 to the management device for a long time. And even at the time of such a disaster, according to this embodiment, while continuing the management of the assembled battery 3 and each cell 2, it is possible to appropriately prevent problems due to overdischarge of the lithium ion cell 2. is there.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, in the above-described embodiment, the case where the lithium ion secondary battery system 1 is applied to the rectifier has been described. However, the lithium ion secondary battery system 1 is applied to other facilities such as an uninterruptible power supply (UPS) and an electric vehicle. You can also. At this time, the number of the lithium ion cells 2 and the assembled batteries 3 are adjusted according to the equipment to be applied. For example, when applied to an uninterruptible power supply, a plurality of assembled batteries 3 as described above are connected in parallel, and for each assembled battery 3, a cell controller 4, an assembled battery management unit 5, a charge / discharge switch 71, 72 and the like, and the assembled battery management unit 5 and the monitoring device 6 are connected so as to be able to perform data communication to constitute the secondary battery system 1.

  In the above embodiment, power is supplied from the assembled battery 3 to the management device only when the commercial power supply 100 is powered down, that is, only when power is supplied from the assembled battery 3 to the load facility 102. Thus, power may be supplied from the assembled battery 3 to the management device. For example, when the assembled battery 3 is used as a storage battery for an electric vehicle, the management device from the assembled battery 3 is used not only when discharging to an automobile as a load facility but also when parking the automobile or charging the assembled battery 3. You may supply electric power to. In addition, when the voltage of any one of the cells 2 becomes lower than the second protection voltage VL3, the first switch 81 is turned off, but the minimum drive voltage of the DC / DC converter 8 is set to the second protection voltage. The voltage may be set to VL3, and the DC / DC converter 8 may not be driven when the voltage of any of the cells 2 becomes lower than the second protection voltage VL3. As a result, since the first switch 81 is on, the cell controller 4 and the assembled battery management unit 5 are automatically activated when the commercial power supply 100 is restored, and data such as the cell state and the assembled battery state is maintained by the maintenance person. Etc. can be provided. Furthermore, although the case where a plurality of lithium ion cells 2 are connected and used and operated as the assembled battery 3 has been described, it is needless to say that the present invention can also be applied when the lithium ion cell 2 is used and operated as a single battery.

1 Lithium ion secondary battery system 2 Lithium ion cell (lithium ion secondary battery)
3 Battery pack 4 Cell controller (management device)
5. Battery pack management unit (management device)
6 Monitoring device (management device)
71 Charge Switch 72 Discharge Switch 8 DC / DC Converter 81 First Switch 82 Second Switch 100 Commercial Power Supply 101 AC / DC Converter 102 Load Equipment

Claims (3)

A lithium ion secondary battery that discharges and supplies power to load equipment, a cell controller that adjusts at least a charging voltage of the lithium ion secondary battery and monitors a cell state, and a plurality of the lithium ion batteries are connected in series. An assembled battery management unit that monitors the state of the assembled battery by receiving from the cell controller , and a monitoring device that stores data including the cell state and the assembled battery state from the assembled battery management unit A lithium ion secondary battery system,
At least when the lithium ion secondary battery supplies power to the load facility, the lithium ion secondary battery supplies power to the cell controller, the assembled battery management unit, and the monitoring device, and the lithium ion secondary battery When the battery voltage is lower than the first protection voltage set lower than the discharge end voltage , the power supply from the lithium ion secondary battery to the monitoring device is stopped, and the lithium ion secondary battery when the voltage reaches the second guard voltage is a minimum voltage necessary for protecting the lithium ion secondary battery lower than the discharge end voltage and the first guard voltage, the lithium ion secondary to stop the power supply to the assembled battery management unit and the cell controller from the next cell, the management instrumentation and the lithium ion secondary battery Door is connected,
A lithium ion secondary battery system characterized by that. The lithium ion secondary battery is float charged,
The charging source and the management device are connected to supply power to the management device from a float charging source when the lithium ion secondary battery is float charged. Item 2. The lithium ion secondary battery system according to Item 1. A cell controller that adjusts at least a charging voltage of a lithium ion secondary battery that discharges and supplies power to a load facility and monitors a cell state, and a state of an assembled battery configured by connecting a plurality of the lithium ion batteries in series in the assembled battery management unit that monitors the reception from the cell controller, the power supply method to the management device and a monitoring device for storing data including the cell state and the assembled battery status from the battery pack management unit There,
At least when the lithium ion secondary battery supplies power to the load facility, the lithium ion secondary battery supplies power to the cell controller, the assembled battery management unit, and the monitoring device, and the lithium ion secondary battery When the battery voltage is lower than the first protection voltage set lower than the discharge end voltage , the power supply from the lithium ion secondary battery to the monitoring device is stopped, and the lithium ion secondary battery when the voltage reaches the second guard voltage is a minimum voltage necessary for protecting the lithium ion secondary battery lower than the discharge end voltage and the first guard voltage, the lithium ion secondary Stopping power supply from the secondary battery to the cell controller and the assembled battery management unit ;
The power supply method to the management apparatus characterized by the above-mentioned.

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