JP2012143020A - Charging system - Google Patents

Abstract

In a charging system that detects a battery pack only by communication with the battery pack, when the battery pack is attached to the charger, the charger is charged in order to shift the battery control circuit from the shutdown state to the normal state. The voltage must be output. However, when a plurality of rechargeable batteries are connected in series, the charging voltage also increases, resulting in the risk of electric shock.
The present invention relates to a charging system including a battery pack 10 in which a plurality of rechargeable batteries 16 are connected in series and a charger 20, and the charger 20 has a battery detection voltage lower than the charging voltage when the battery is not connected. Even if the battery control circuit 14 of the battery pack 10 is in a shutdown state and the battery pack 10 and the charger 20 cannot communicate with each other by outputting the signal at a constant or pulse, the battery control circuit is controlled by the battery detection voltage. 14 is configured to shift to a normal state so that the battery pack 10 and the charger 20 can communicate with each other.
[Selection] Figure 1

Description

  The present invention provides a charging system comprising a battery pack in which rechargeable batteries are connected in series and having a battery control circuit, and a charger for charging the battery pack, and the charger is charged until the connection of the battery pack is detected. It relates to a safe charging system that does not start.

  In recent years, interest in environmental issues has increased. Under such circumstances, farm machinery such as motorcycles and cultivators that have conventionally used an engine as a drive source have been attracting attention because of their CO2 emission and noise, which are driven by a motor using a rechargeable battery as a power source. Rechargeable batteries used in main devices such as motorcycles and cultivators are required to have high safety and long driving time. In order to ensure high safety, the rechargeable battery is a battery pack that controls the charging / discharging of the rechargeable battery and incorporates a battery control circuit (Battery Management Unit, hereinafter referred to as BMU) having various protection functions. The BMU monitors whether the rechargeable battery is in an unsafe state such as overdischarge, overvoltage, overcurrent.

  In addition, because the main unit is driven for a long time, not only the capacity of the rechargeable battery is increased, but also the power consumption of the BMU is reduced. The BMU is connected to the main unit to monitor the safety of the rechargeable battery. It is working even when it is not (or the body is not working). However, as long as the BMU is in operation, the rechargeable battery consumes power, so if you try to use the main unit without using the main unit for a long time, there is almost no remaining capacity of the rechargeable battery. The main device cannot be used. Therefore, when the rechargeable battery is not used in the main device for a certain period of time, the BMU is shut down in order to reduce the power consumption of the BMU, thereby suppressing the decrease in capacity of the rechargeable battery.

  Further, even when the rechargeable battery is overdischarged and the power supply voltage of the BMU cannot be maintained, the BMU is shut down to protect the rechargeable battery.

  In addition, chargers for charging this battery pack generally charge the battery pack with constant voltage and constant current control, but in order to improve safety during charging, the charger has a built-in microcomputer and a battery. It communicates with the pack, always obtains information such as the voltage and temperature of the battery from the battery pack, and performs charge control based on the information (see, for example, Patent Document 1 and Patent Document 2).

JP 2004-187329 A JP 2010-115087 A

  The number of rechargeable batteries connected in series with battery packs is increasing along with the increase in the output of the main unit, but as the number of rechargeable batteries connected in series increases, the voltage of the battery pack increases and there is a risk of electric shock. Will occur. In particular, when the rechargeable battery is a lithium ion battery having a full charge voltage of about 4.2 V, when 10 or more batteries are connected in series, the voltage between the terminals of the battery pack charged to near full charge is 42 V or more. It is defined as dangerous voltage, and measures that cannot be easily touched are required.

  In battery packs, switches that turn charging / discharging on and off (for example, semiconductor switches such as MOS-FETs) are turned off, and terminals are placed in the back of the battery case so that they cannot be easily touched. We are taking measures. On the other hand, the charger also takes measures to prevent charging until the BMU of the battery pack and the microcomputer of the charger communicate bidirectionally and the connection confirmation is completed.

  However, as described above, when the battery pack is shut down in order to reduce the power consumed by the battery pack's BMU, the BMU will shut down even if the battery pack is attached to the charger for charging. Connection confirmation communication cannot be performed. Therefore, the charger always outputs a voltage so that communication can be started even when the BMU is shut down. When a battery pack in which the BMU is in a shutdown state is attached, the battery pack is output by the output voltage of the charger. Must be started to start communication. However, conventional techniques such as Patent Document 1 and Patent Document 2 do not consider the output voltage of the charger for starting the BMU, and charge a battery pack in which 10 or more rechargeable batteries are connected in series. In the case of a battery charger, the charging voltage is 42V. Therefore, the battery charger must always output a voltage of 42V or more in order to detect the connection of the battery pack, and there is a risk of electric shock. As a countermeasure, measures such as covering with a cover or the like so as not to contact the terminal portion of the charger are taken until the battery pack is mounted, but the number of parts increases, resulting in an increase in cost.

  The present invention has been made in view of the above problems, and in a battery pack having a built-in BMU and a charger capable of communicating with the battery pack, no dangerous voltage is output until the battery pack is attached to the charger. It is an object of the present invention to provide a safe charging system in which a battery pack is mounted on a charger, the charger reliably detects connection of the battery pack, and the charger does not output dangerous voltage until charging is started.

  In order to achieve the above object, the present invention provides a battery pack including a rechargeable battery, a battery control circuit, a charge to the rechargeable battery, a current switch for turning on / off a discharge current, the battery pack, a positive / negative terminal, and communication Connected at the terminal, connected to the charging constant voltage constant current circuit for controlling the charging current and charging voltage to be charged to the rechargeable battery of the battery pack by receiving power from the commercial power supply and the output of this constant voltage constant current circuit In the charging system comprising a charger comprising a charging output switch for supplying to the battery pack and a microcomputer for controlling on / off of each switch of the charger while communicating with the battery pack, the charger Includes a battery detection voltage power supply for outputting a battery detection voltage for detecting the battery pack, and a detection switch for turning on / off the output of the battery detection voltage. The battery detection voltage is set lower than the charging voltage and output from the output terminal of the charger. When the battery pack is connected, the battery detection voltage is used to activate the battery control circuit of the battery pack. The battery pack sends an activation signal to the charger, and when the microcomputer of the charger receives the signal, the charger recognizes the connection of the battery pack, turns off the detection switch, turns on the charge switch, In the battery pack, the battery control circuit is configured to start charging by turning on a current switch of the battery pack by a battery control circuit.

  The battery detection voltage is output from the output terminal of the charger in a pulsed manner by periodically turning on / off the detection switch.

  In addition, a rechargeable battery, a battery control circuit, a rechargeable battery, a battery pack having a charge / discharge switch for turning on / off a discharge current, and the battery pack connected to the positive / negative terminal and the communication terminal, from a commercial power source A charging constant voltage / constant current circuit for controlling a charging current and a charging voltage for charging the charging battery of the battery pack upon supply of power and an output of the charging constant voltage / constant current circuit are supplied to the connected battery pack. In a charging system comprising a charger that communicates between the charging switch and the battery pack and controls on / off of each switch of the charger, the charging is performed when the battery pack is not connected. When the output voltage of the constant voltage constant current circuit is lower than the charging voltage, the battery detection voltage is output from the output terminal as the battery detection voltage, and the battery pack is connected The battery control circuit of the battery pack is activated by the battery detection voltage of the battery pack, the battery pack transmits an activation signal to the charger, and the charger recognizes the connection of the battery pack when the signal is received by the microcomputer of the charger. The charging constant voltage constant current circuit output voltage is switched to a charging voltage, while the battery pack is configured such that a charging / discharging switch of the battery pack is turned on by the battery control circuit to start charging. Charging system.

  The battery detection voltage is output from the output terminal of the charger in a pulsed manner by periodically turning on / off the charging switch.

  According to the present invention, in a charging system in which a battery pack in which a large number of rechargeable batteries are connected in series and the BMU is shut down and cannot be activated unless a voltage is applied from the outside, the battery pack is attached to the charger. It is possible to provide a safe charging system that does not need to output a high voltage that may cause an electric shock when it is not.

The electric circuit block diagram of the charging system in one Embodiment of Claim 1 or Claim 2 Pulse waveform diagram of the battery detection voltage Operation diagram of battery pack and charger when the battery detection voltage is changed to a pulse waveform The electric circuit block diagram of the charging system in one Embodiment of Claim 3 or Claim 4

  A battery pack having a current switch for turning on / off charging / discharging current to / from the rechargeable battery, battery control circuit, and rechargeable battery, and connected to the battery pack via a positive / negative terminal and a communication terminal, and supplying power from a commercial power source A charging constant voltage constant current circuit for controlling a charging current and a charging voltage for charging the charging battery of the battery pack upon receipt thereof, and a charge output switch for supplying the output of the constant voltage constant current circuit to the connected battery pack And a battery charger for detecting a battery pack in a charging system comprising a microcomputer that communicates with the battery pack and controls on / off of each switch of the charger. It has a battery detection voltage power supply that outputs voltage, and a detection switch that turns on and off the output of this battery detection voltage. When the battery pack is connected, the battery control circuit of the battery pack is activated by this battery detection voltage, and then the battery pack transmits an activation signal to the charger. When the signal is received by the microcomputer of the charger, the charger recognizes the connection of the battery pack, turns off the detection switch, and turns on the charge switch. A charging system is configured to start charging by turning on a current switch of a battery pack. In addition, the battery detection voltage can be output in a pulse form from the output terminal of the charger by periodically turning on / off the detection switch.

  In addition, a rechargeable battery, a battery control circuit, a rechargeable battery, a battery pack having a charge / discharge switch for turning on / off a discharge current, and the battery pack connected to the positive / negative terminal and the communication terminal, from a commercial power source A charging constant voltage / constant current circuit for controlling a charging current and a charging voltage for charging the charging battery of the battery pack upon supply of power and an output of the charging constant voltage / constant current circuit are supplied to the connected battery pack. In a charging system comprising a charger that communicates between the charging switch and the battery pack and controls on / off of each switch of the charger, the charging is performed when the battery pack is not connected. When the output voltage of the constant voltage constant current circuit is lower than the charging voltage, the battery detection voltage is output from the output terminal as the battery detection voltage, and the battery pack is connected The battery control circuit of the battery pack is activated by the battery detection voltage of the battery pack, the battery pack transmits an activation signal to the charger, and the charger recognizes the connection of the battery pack when the signal is received by the microcomputer of the charger. The battery pack may be configured such that the output voltage of the charging constant voltage constant current circuit is switched to a charging voltage, while the battery control circuit turns on a charge / discharge switch of the battery pack to start charging. . Further, the battery detection voltage output from the charging constant voltage constant current circuit can be output in a pulse form from the output terminal of the charger by periodically turning on and off the charging switch.

  According to the present invention, even if the BMU of the battery pack is in a shutdown state, the charger outputs a voltage lower than the charging voltage at a constant or pulse, so that the BMU of the battery pack is brought into a normal state by the voltage. When the transition is possible and the BMU and the microcomputer of the charger communicate with each other and the connection is normally detected, charging is started. As a result, even when the charging voltage is high, there is no danger of an electric shock because the charger outputs a low voltage when the battery pack is not connected even when the battery pack is not connected even when the voltage is high.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below specifically explains the present invention, and the present invention does not specify the charging system and the battery detection method below.

  FIG. 1 is an electric circuit diagram schematically showing an electrical configuration of a battery pack and a charger constituting the charging system of the present invention.

  The battery pack 10 is formed with a battery pack terminal portion on one side thereof so that the battery pack terminal portion can be attached to the charging terminal portion of the charger 20, and includes a positive electrode terminal 11, a negative electrode terminal 12, and a communication terminal 13. Inside, there are a rechargeable battery 16 for supplying power to a main device to which the battery pack 10 is attached, a battery control circuit 14 (hereinafter referred to as BMU14) incorporating charging / discharging and various protection functions of the rechargeable battery, and signals of the BMU14. The charging / discharging switch 15 is used to turn on / off charging / discharging. The battery pack 10 includes a plurality of rechargeable batteries 16 connected in series.

  In this embodiment, a lithium ion battery is used, and the battery voltage when fully charged is 4.2V. Therefore, in a battery pack in which 10 batteries are connected in series, the total voltage (hereinafter referred to as battery voltage) of the rechargeable battery 16 when fully charged is 42V. The BMU 14 reads the individual battery voltages of the rechargeable batteries 16 connected in series and performs an appropriate operation according to the voltage. For example, if one of the voltages of the rechargeable battery becomes lower than a certain voltage while using the main device, a signal for turning off the charge / discharge switch 15 is transmitted to stop discharging, or the battery voltage is further decreased. If it is not used for a certain period of time, the function of the BMU 14 itself is shut down to reduce the power consumption of the rechargeable battery 16.

  The charger 20 generates a predetermined current / voltage to charge the rechargeable battery 16 of the battery pack 10 by AC input, and a charging terminal portion is configured so that the battery pack 10 can be mounted on one side surface. Similar to the battery pack terminal portion of the battery pack 10, the charging terminal portion includes a positive electrode terminal 21, a negative electrode terminal 22, and a communication terminal 23.

  In the charging system configured as described above, the battery pack terminal portion of the battery pack 10 is electrically connected by being attached to the charging terminal portion of the charger 20.

  Next, the configuration of the charger 20 will be described. The charger 20 rectifies an external power source (AC100V in this embodiment) into a direct current and supplies power to the transformer 33 by the switching control circuit 32, and the secondary side from the primary side power circuit 31. A transformer 33 that supplies power to the battery, a rectifying / smoothing circuit 35 for charging output that receives power from the transformer 33 and rectifies and smoothes it, a constant voltage constant current circuit 26 for charging that generates charging power, and a constant voltage constant current circuit for charging 26 and a positive electrode terminal 21, a charge switch 27 for turning on / off the supply of charging power, and a positive voltage terminal 21 and a negative electrode terminal 22, which are connected between the positive electrode terminal 21 and the negative electrode terminal 22. A resistor 29; a current detection resistor 30 for converting a charging current into a voltage; a rectification / smoothing circuit 36 for microcomputer power supply that rectifies and smoothes power supplied from a transformer 33; and a rectifier for microcomputer power supply The microcomputer power supply 34 for generating the microcomputer power supply voltage from the sliding circuit 36, communication with the battery pack 10, transmission of on / off signals of each switch, charging control and detection of overvoltage and overcurrent of the battery pack 10 for charging The microcomputer 24 having the protection function to stop, the battery detection voltage power supply unit 25 for lowering the output voltage when the battery pack is not connected, the output voltage of the battery detection voltage power supply unit 25 is turned on / off, and charging is performed during charging The detection switch 28 is configured to prevent the output voltage of the constant voltage constant current circuit 26 from being output to the output terminal.

  First, the charging operation when the BMU 14 of the battery pack 10 is not shut down will be described. When the battery pack 10 is attached to the charger 20 and each terminal contacts as described above, the microcomputer 24 and the BMU 14 communicate with each other. When the microcomputer 24 detects the connection of the battery pack 10 by communication from the BMU 14 to the microcomputer 24, the microcomputer 24 next transmits a signal to the BMU 14. Thereby, the BMU 14 also recognizes the connection of the charger 20 and transmits information such as the battery voltage and the temperature in the battery pack 10 to the charger 20. When the charger 20 receives this signal and determines that the battery pack 10 can be charged, the microcomputer 24 turns off the detection switch 28 and transmits a signal for turning on the charging switch 27 in order to start charging. Further, the BMU 14 turns on the charge / discharge switch 15. When charging is started, the charging constant voltage constant current circuit 26 detects a value obtained by converting the battery voltage divided by the battery voltage dividing resistor 29 and the charging current into a voltage by the current detection resistor 30, and thereby the constant voltage constant current circuit 26. Current control is performed to charge the battery pack 10 (that is, the rechargeable battery 16).

  The microcomputer 24 communicates with the BMU 14 of the battery pack 10 at regular intervals during charging, and receives information such as individual battery voltages connected to the battery pack 10 in series and the internal temperature of the battery pack 10. Also, the microcomputer 24 itself acquires the battery voltage divided by the battery voltage dividing resistor 29, acquires the charging current from the current detection resistor 30, and performs optimum charging control for the charging battery based on the information. A signal is sent to the constant voltage constant current circuit 26 for charging output so as to be performed. At the same time, the microcomputer 24 transmits a signal to turn off the charging switch 27 in order to stop charging when detecting an abnormal state such as overvoltage or overcurrent. Eventually, when the charging current becomes equal to or lower than a predetermined value, or when a charging completion signal is received from the battery pack 10, a charging stop signal is sent to the charging constant voltage constant current circuit 26 and the charging switch 27 is switched off. Is transmitted, and charging is completed.

  Next, an operation when the BMU 14 is in a shutdown state due to a long-term unused or a decrease in battery voltage due to the operation of the main device will be described. In this case, since the BMU 14 of the battery pack 10 is not operating even if the respective terminal portions of the battery pack 10 and the charger 20 are in contact with each other, the battery pack 10 cannot transmit a signal to the charger 20 and is charged. The device 20 cannot detect the connection of the battery pack 10 and cannot start charging.

  Therefore, in the present invention, a battery detection voltage lower than the charging voltage is output in order to bring the BMU 14 from the shutdown state to the normal state. However, this voltage must be higher than the voltage at which the BMU 14 can transition from the shutdown state to the normal state. This operation will be described below.

  Until the battery pack 10 is attached to the charger 20, the charge switch 27 is turned off, and the battery detection voltage, which is the output of the battery detection voltage power supply 25, is output from between the positive terminal 21 and the negative terminal 22 of the charger 20. The detection switch 28 is turned on. At this time, the output voltage may be a constant voltage, or may be a pulse waveform that repeatedly turns on and off in order to reduce the power consumption of the charger 20 as shown in FIG. However, the ON time when the pulse waveform is set must be set to a time during which the BMU 14 is activated and a signal can be transmitted to the microcomputer 24 of the charger 20.

  When the battery pack 10 is attached to the charger 20, the BMU 14 shifts from the shutdown state to the normal state by the battery detection voltage output from the charger 20. And a signal is transmitted to the microcomputer 24 of the charger 20, and the microcomputer 24 recognizes the connection of the battery pack 10. At this time, if the battery detection voltage is output in a pulse, the pulse is changed to a constant voltage at this time. Next, a signal is transmitted from the microcomputer 24 to the BMU 14. Thereby, the BMU 14 also recognizes the connection of the charger 20 and transmits information such as the battery voltage and the temperature in the battery pack 10 to the charger 20. When the charger 20 receives this signal and determines that the battery pack 10 can be charged, the microcomputer 24 turns off the detection switch 28 and transmits a signal for turning on the charging switch 27 in order to start charging. Further, the BMU 14 turns on the charge / discharge switch 15. Thereby, charging is started. The subsequent charging operation is the same as when the BMU 14 is not shut down.

  FIG. 3 shows an operation in which the battery detection voltage is changed to a pulse waveform. In the present embodiment, the battery detection voltage is 10V. This voltage is sufficient to allow the BMU 14 to transition from the shutdown state to the normal state. The on / off time was 1 second. This is sufficient time that the BMU 14 is activated and a signal can be transmitted to the microcomputer 24 of the charger 20.

  Until the battery pack 10 is connected, the output terminal voltage of the charger 20 is output on the pulse. When the battery pack 10 is attached to the charger 20 (A), the BMU 14 shifts from the shutdown state to the normal state and transmits a signal to the charger 20 (B). When the charger 20 receives this signal, the battery detection voltage changes from a pulse to a constant voltage. Subsequently, a signal indicating connection detected from the charger 20 is transmitted to the battery pack 10 (C). Next, when the charger 20 receives information on the battery pack 10 from the BMU 14 (D), the charger 20 turns off the detection switch 28 and turns on the charge switch 27 in order to start charging. Thereby, the output of the charger can output a charging voltage (E). Further, the BMU 14 is charged when the charge / discharge switch 15 is turned on (F).

  In the above embodiment, the battery detection voltage power supply unit 25 and the detection switch 28 are used as the battery detection voltage for detecting the connection of the battery pack 10, but the battery detection voltage is supplied from the charging constant voltage constant current circuit 26. It can also be realized by lowering the output voltage. FIG. 4 shows the embodiment. In FIG. 4, until the connection of the battery pack 10 is detected and charging is started (until E in FIG. 3), a signal is transmitted from the microcomputer 24 to the constant voltage constant current circuit 26 for charging, and the constant voltage constant for charging is constant. The current circuit 26 outputs a battery detection voltage lower than the charging voltage, turns on the charging switch 27, and outputs the battery detection voltage. Moreover, it is also possible to output in a pulse form by transmitting a signal from the microcomputer 24 to the charging switch 27. The operation up to the start of charging is the same as in FIG. 3 except for the location where the battery detection voltage is output, and the detailed description of the operation is omitted.

  Thus, the charger 20 can prevent the risk of electric shock without outputting the charging voltage until charging is started.

  In this embodiment, since the AC 100V external power supply is used, the transformer 33 is used. Of course, when a DC voltage is used as the external power supply, an optimum circuit system such as a DC-DC converter can be used.

  As described above, according to the charging system of the present invention, even if the BMU of the battery pack is in a shutdown state in order to reduce power consumption, the charger can maintain a voltage lower than the charging voltage constant or pulsed. The BMU of the battery pack can shift to the normal state by the output voltage, and the BMU and the microcomputer of the charger communicate with each other, and charging is started when the connection is detected normally. As a result, even when the charging voltage is high, there is no danger of an electric shock because the charger outputs a low voltage until charging is started, even in the case of a high voltage that may cause an electric shock. Further, a cover for preventing contact or the like is unnecessary, and the cost of the charger can be reduced.

DESCRIPTION OF SYMBOLS 10 Battery pack 11 Positive electrode terminal 12 Negative electrode terminal 13 Communication terminal 14 Battery control circuit (Battery Management Unit, BMU)
DESCRIPTION OF SYMBOLS 15 Charging / discharging switch 16 Rechargeable battery 20 Charger 21 Positive electrode terminal 22 Negative electrode terminal 23 Communication terminal 24 Microcomputer 25 Battery detection voltage power supply unit 26 Charging constant voltage constant current circuit 27 Charging switch 28 Detection switch 29 Battery voltage dividing resistor 30 Current Detection resistor 31 Primary side power supply circuit 32 Switching control circuit 33 Transformer 34 Microcomputer power supply 35 Charge output rectification smoothing circuit 36 Microcomputer power supply rectification smoothing circuit

Claims (4)

A rechargeable battery, a battery control circuit, a rechargeable battery, a battery pack having a charge / discharge switch for turning on / off the discharge current, and the battery pack connected to the positive / negative terminal and the communication terminal. A charging constant voltage constant current circuit for controlling the charging current and charging voltage for charging the charging battery of the battery pack in response to the supply, and for supplying the output of the charging constant voltage constant current circuit to the connected battery pack In a charging system including a charger that communicates between a charging switch and the battery pack and controls on / off of each switch of the charger, the charger detects connection of the battery pack. A battery detection voltage power supply unit for outputting a battery detection voltage to be used at the time, and a detection switch for turning on / off the output of the battery detection voltage. Is set lower than the charging voltage and output from the output terminal of the charger, and when the battery pack is connected, the battery control circuit of the battery pack is activated by this battery detection voltage, and the battery pack generates an activation signal. The charger recognizes the connection of the battery pack when the signal is received by the microcomputer of the charger, and the detection switch is turned off and the charge switch is turned on, while the battery pack has a battery control circuit. The charging system is configured such that the charging / discharging switch of the battery pack is turned on to start charging. 2. The charging system according to claim 1, wherein the battery detection voltage is output in a pulse form from the output terminal of the charger by periodically turning on and off the detection switch. A rechargeable battery, a battery control circuit, a rechargeable battery, a battery pack having a charge / discharge switch for turning on / off the discharge current, and the battery pack connected to the positive / negative terminal and the communication terminal. A charging constant voltage constant current circuit for controlling the charging current and charging voltage for charging the charging battery of the battery pack in response to the supply, and for supplying the output of the charging constant voltage constant current circuit to the connected battery pack In a charging system including a charger that communicates between a charging switch and the battery pack and controls on / off of each switch of the charger, the charging constant is set when the battery pack is not connected. When the output voltage of the voltage constant current circuit is lower than the charging voltage, the battery detection voltage is output from the output terminal as the battery detection voltage, and this battery is connected. The battery control circuit of the battery pack is activated by the detected voltage, the battery pack transmits an activation signal to the charger, and the charger recognizes the connection of the battery pack by receiving the signal from the microcomputer of the charger. The output voltage of the constant voltage constant current circuit for charging is switched to the charging voltage, while the battery pack is configured such that the battery control circuit turns on a charge / discharge switch of the battery pack to start charging. Charging system. 4. The charging system according to claim 3, wherein the battery detection voltage is output in a pulse form from the output terminal of the charger by periodically turning on / off the charging switch.

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