JP2009201260A - Multi-shaft motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-shaft motor drive device in which a surplus electric power can be accumulated in a storage battery or the like to achieve energy saving, the size and cost of the storage battery can be reduced for operation of the storage battery at high efficiency, and even a regenerative power in a short period of time can be accumulated in the storage battery. <P>SOLUTION: In a multi-shaft motor drive device 1 includes a DC power supply line 10, and a plurality of inverter modules 20 each of which includes an inverter circuit 21 that converts a DC power supply voltage VDC from the DC power supply line 10 into an AC power supply voltage which is supplied to an AC motor 60. A coil unit 40 and a storage battery 50, instead of the AC motor 60, are connected to a drive power output end 23 of some inverter modules 20 among the plurality of inverter modules 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-axis motor driving device.

  Conventionally, in order to simultaneously drive a multi-axis AC motor, the voltage supplied from one AC power source is converted into a DC power source voltage, and this DC power source voltage is converted into AC power by an inverter circuit corresponding to each AC motor. A method of reconverting and supplying to each AC motor is used. In this system, when a certain AC motor is powered and another AC motor is regenerated, energy is exchanged between these AC motors via a DC power supply line (DC bus). Therefore, compared with the configuration in which the power supply voltage is individually supplied to each inverter circuit, the power efficiency is good and the energy saving effect can be expected. However, in the conventional apparatus, when the regenerative energy becomes larger than the power running energy, a method of consuming surplus power with a resistor is adopted, and such a method is not preferable from the viewpoint of energy saving.

For example, an electric motor drive device described in Patent Document 1 supplies a DC power supply voltage converted from a three-phase AC power supply voltage in parallel to each inverter circuit of a plurality of three-phase AC motors, and each inverter circuit again generates a three-phase power. It has a configuration for converting to AC voltage and supplying power to the three-phase AC motor. In order to solve the above problem, the battery recharges the electric power regenerated from each electric motor to the DC power supply line via the inverter circuit, and when the regenerative power exceeds a predetermined value, the regenerative power is converted into a three-phase AC voltage. And converted back to a three-phase AC power source.
JP 2000-201492 A

  However, in the above system, it is common to convert the AC power supply voltage from one AC power supply to a DC power supply voltage by rectifying, and therefore the magnitude of the DC power supply voltage is 140 [V] to 600 [V]. ] And relatively high. For this reason, when a storage battery (battery) is directly connected to the DC power supply line as in the configuration described in Patent Document 1, it is necessary to make the input voltage upper limit value on the specification of the storage battery higher than that of a general storage battery. It becomes a factor that hinders reduction and miniaturization. Moreover, since the amount of electricity stored in the storage battery is not actively controlled, it is difficult to operate the storage battery with high efficiency, and it is necessary to allow for a sufficient margin for the maximum capacity of the storage battery. Furthermore, when the terminal voltage of the storage battery and the DC power supply voltage are set close to each other, if the surplus power suddenly increases, the terminal voltage of the storage battery may become excessive and the storage battery may break down. It becomes difficult to store electricity in the storage battery.

  The present invention has been made in view of the above-mentioned problems, and it is possible to realize energy saving by storing surplus power in a storage battery and the like, and it is possible to reduce the size and cost of the storage battery and the like. An object of the present invention is to provide a multi-axis motor drive device that can be operated and can store electricity in a storage battery or the like even with a short regenerative power.

  In order to solve the above-described problems, a multi-axis motor driving apparatus according to the present invention is a multi-axis motor driving apparatus for driving a plurality of AC motors, wherein a DC power supply line and a DC power supply voltage from the DC power supply line are AC N inverter modules (N is an integer greater than or equal to 3) having inverter circuits for converting the power supply voltage to supply to a plurality of AC motors, and each of the N inverter modules includes a DC power supply line and an electric circuit. A power input terminal for receiving a DC power supply voltage and a drive power output terminal electrically connected to each AC motor for supplying the AC power supply voltage to the AC motor, and N inverters Instead of an AC motor, a coil and a power storage means are connected to the drive power output terminals of M (N−M ≧ 2 and M is an integer of 1 or more) inverter modules among the modules. And wherein the Rukoto.

  Inverter circuits used in AC motors perform DC-AC conversion. If a coil is connected to such an inverter circuit, a DC-DC conversion circuit can be configured, and conversion is performed by controlling the inverter circuit. The subsequent DC voltage value can be set arbitrarily. In the multi-axis motor driving apparatus described above, a DC power source is connected by connecting a coil and a storage means (storage battery, capacitive element, etc.) to the drive power output terminals of a part (M) of inverter modules of the N inverter modules. Regardless of the DC power supply voltage value in the line, the terminal voltage value of the power storage means can be set to an arbitrary magnitude by controlling the inverter circuit. Therefore, even when the DC power supply voltage in the DC power supply line is a relatively high voltage, for example, 140 [V] to 600 [V], the upper limit value of the input voltage in the specification of the power storage means can be kept low. Reduction and downsizing can be realized. Further, it is possible to positively control the amount of electricity stored in the electricity storage means, and the electricity storage means can be operated with high efficiency. Furthermore, even if the surplus power suddenly increases, the terminal voltage of the power storage means can be kept stable, so that regenerative power for a short time can be stored in the power storage means.

  The multi-axis motor driving device may further include a control unit that drives the inverter circuits of the M inverter modules to control charging / discharging of the power storage means. Thereby, the terminal voltage of an electrical storage means can be suitably controlled to arbitrary magnitude | sizes. In this case, each of the N inverter modules may include an integrated circuit for driving the inverter circuit, and in the M inverter modules, a control unit may be provided in the integrated circuit. Alternatively, the multi-axis motor driving device may include a control module having a control unit separately from the N inverter modules.

  The multi-axis motor drive device may be characterized in that one end of the coil is connected to the drive power output end by a connector that can be attached to and detached from the drive power output end of the inverter module. Thus, by making a coil detachable with respect to an inverter module, the inverter module for driving an AC motor can be easily used for power storage means control. For example, when a multi-axis module having five control axes is used for a processing machine that requires five control axes, and then the multi-axis motor drive device is to be applied to a processing machine that requires four control axes. The remaining one control axis can also be used as a power storage means.

  Further, the multi-axis motor driving device may be characterized in that each inverter circuit of the N inverter modules is configured by a three-phase inverter bridge. As a result, N inverter modules can be used to drive a three-phase AC motor, which is a general AC motor, and a part (M) of inverter modules can be used for power storage means control, resulting in low cost. Can be realized. Further, the coil can be reduced in size by performing appropriate phase control.

  The multi-axis motor drive device may further include a rectifier that converts a voltage from an AC power source into a DC power source voltage and supplies the DC power source line to the DC power source line. Alternatively, the multi-axis motor driving device may further include a connector for connecting a rectifier that converts a voltage from an AC power source into a DC power source voltage and supplies the DC power source line to the DC power source line. With any one of these configurations, the DC power supply voltage can be suitably supplied to the DC power supply line.

  According to the multi-axis motor drive device of the present invention, it is possible to save energy by storing surplus power in a power storage means such as a storage battery, and the power storage means can be reduced in size and cost, and the power storage means can be operated with high efficiency. It is possible to store power in the power storage means even when the regenerative power is short.

  Embodiments of a multi-axis motor driving device according to the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a circuit diagram showing a configuration of an embodiment of a multi-axis motor driving apparatus according to the present invention. The multi-axis motor drive device 1 of this embodiment is a device for driving a plurality of AC motors M, and is connected to the DC power supply line 10 and the DC power supply line 10 (N is 3). The inverter module 20 of the above integer) and the power converter module 30 electrically connected to the DC power supply line 10 are provided.

  The DC power supply line 10 is a DC bus for supplying a DC power supply voltage VDC to each inverter module 20. The DC power supply line 10 is composed of two wires that supply a positive voltage and a negative voltage, respectively. The DC power supply line 10 is supplied with a DC power supply voltage VDC from the power supply converter module 30. The power converter module 30 is a rectifier according to the present embodiment, and is formed by connecting three sets of two diodes connected in series in parallel. Then, the power converter module 30 converts the three-phase AC power supply voltage from the AC power supply P into the DC power supply voltage VDC and supplies it to the DC power supply line 10. Such a rectifier may be included in the multi-axis motor driving device 1 as in the present embodiment, or a connector for connecting an external rectifier to the DC power supply line 10 may be provided in the multi-axis motor driving device. The structure provided may be sufficient.

  The N inverter modules 20 each have an inverter circuit 21 for converting the DC power supply voltage VDC from the DC power supply line 10 into a three-phase AC power supply voltage and supplying it to each AC motor 60. Each of the N inverter modules 20 is electrically connected to the DC power supply line 10 to receive the DC power supply voltage VDC, and each AC motor 60 is connected to the AC power supply voltage. It has a drive power output end 23 to be supplied to each AC motor 60. However, among the N inverter modules 20, M (N−M ≧ 2 and M is an integer equal to or greater than 1; in this embodiment, M = 1), the drive power output end 23 of the inverter power supply 20 has an AC motor. Instead of 60, a coil unit 40 and a storage battery (battery) 50 are connected. The circuit configuration of the inverter circuit 21 of the inverter module 20 to which the coil unit 40 and the storage battery 50 are connected is the same as the circuit configuration of the inverter circuit 21 of the other inverter module 20 to which the AC motor 60 is connected. .

  The inverter circuit 21 of each inverter module 20 is configured by a three-phase inverter bridge. That is, each inverter circuit 21 is formed by connecting three sets (bridges) of two transistors connected in series in parallel, and one end of each transistor set is connected to the DC power supply line 10 on the positive voltage side. The other end is connected to the DC power supply line 10 on the negative voltage side. The connection point between the transistors in each transistor set is connected to the power input terminal of each AC motor or one end of the coil unit 40. A diode is connected in reverse direction in parallel with each transistor.

  The coil unit 40 is composed of three coils (reactors) corresponding to each phase, and one end of each coil is connected to each phase bridge of the inverter circuit 21, and the other end of each coil is the storage battery 50. Is connected to one terminal. In this embodiment, one end of each coil is connected to the drive power output end 23 of the inverter module 20 by a detachable connector, and the replacement with the AC motor 60 is ensured. The multi-axis motor drive device 1 may include a single coil connected to all the three-phase bridges of the inverter circuit 21 instead of the coil unit 40. According to this structure, the capacity | capacitance of a coil can be freely changed according to the magnitude | size of the electric current of charging / discharging, the capacity | capacitance of a storage battery, and a voltage. Therefore, since it is not necessary to change the entire multi-axis motor driving device in response to changes in operating conditions or changes in the applied device, it is very easy to handle.

  The storage battery 50 is a power storage means in the present embodiment. As the storage battery 50, a low-voltage battery such as 24V, 48V, or 96V is preferably used. One terminal of the storage battery 50 is connected to the coil unit 40, and the other terminal is connected to the negative voltage side of the DC power supply line 10. In addition, as an electrical storage means, instead of the storage battery 50, you may use other electric elements, such as a capacitive element (capacitor), for example.

  FIG. 2 is a diagram illustrating an example of a configuration for controlling the inverter circuit 21 of the inverter module 20 to which the AC motor 60 is connected. As shown in FIG. 2, the multi-axis motor driving device 1 further includes an A / D converter 24, a control microcomputer 25, and a motor control PWM generation circuit 26. The control microcomputer 25 and the motor control PWM generation circuit 26 are provided in an integrated circuit for driving the inverter circuit 21 and are mounted on the inverter module 20 together with the A / D converter 24. The A / D converter 24, the control microcomputer 25, and the motor control PWM generation circuit 26 supply AC power supply voltage from the inverter circuit 21 to the AC motor 60, and power regeneration from the AC motor 60 to the inverter circuit 21. To control.

  Specifically, the A / D converter 24 inputs a voltage value and a current value between each phase of the inverter circuit 21 and the AC motor 60 and a DC power supply voltage value in the DC power supply line 10. The A / D converter 24 digitizes this information and transmits it to the control microcomputer 25. The control microcomputer 25 determines either power running or regeneration based on operation input information input from the outside of the inverter module 20 and information from the A / D converter 24 and is provided to the inverter circuit 21. Determine the drive signal. The motor control PWM generation circuit 26 generates a drive signal (PWM signal) based on a command from the control microcomputer 25, and provides this drive signal to the base of each transistor of the inverter circuit 21.

  Here, FIG. 3 is a diagram for explaining a drive signal generation method in the motor control PWM generation circuit 26. A graph A shown in FIG. 3A shows a periodic triangular wave signal, and a graph B is a command value for determining the PWM duty ratio. Graph C shows a waveform of a drive signal applied to the base of a transistor connected to the positive voltage side (hereinafter referred to as a positive side transistor) among the transistors included in the inverter circuit 21, and graph D shows a negative value. The waveform of the drive signal applied to the base of a transistor connected to the voltage side (hereinafter, negative side transistor) is shown.

  The motor control PWM generation circuit 26 compares the triangular wave signal (graph A) with the command value (graph B). If the triangular wave signal is larger than the command value, the drive signal (graph C) to the positive side transistor is output. The drive signal (graph D) to the negative side transistor is set to the low level. Conversely, when the command value is larger than the triangular wave signal, the drive signal to the positive side transistor is set to the low level and the drive signal to the negative side transistor is set to the high level. The duty ratio of the drive signal can be controlled by changing the magnitude of the command value input to the motor control PWM generation circuit 26. In order to avoid that the positive side transistor and the negative side transistor are simultaneously turned on, the drive signal (graph C) to the positive side transistor is set to the high level, and the drive signal to the negative side transistor (graph D) is set. ) Is set to the high level, a period (dead time) in which both the drive signal to the positive side transistor and the drive signal to the negative side transistor are set to the low level may be provided.

  Further, the command value input to the motor control PWM generation circuit 26 fluctuates in a sine wave shape as shown in FIG. Therefore, the motor control PWM generation circuit 26 generates a PWM signal (graph E) whose duty ratio periodically changes as a drive signal.

  FIG. 4 is a diagram illustrating an example of a configuration for controlling the inverter circuit 21 of the inverter module 20 to which the coil unit 40 and the storage battery 50 are connected. As shown in FIG. 4, the multi-axis motor driving apparatus 1 includes an A / D converter 27, a control microcomputer 28, and a motor control PWM generation circuit 29, which are the A / D converters shown in FIG. The converter 24, the control microcomputer 25, and the motor control PWM generation circuit 26 are implemented by the same types of circuit components. That is, the control microcomputer 28 and the motor control PWM generation circuit 29 are provided in an integrated circuit for driving the inverter circuit 21, and are mounted on the inverter module 20 together with the A / D converter 27. The connection relationship between the A / D converter 27, the control microcomputer 28, and the motor control PWM generation circuit 29 is the same as in FIG. 2, but these operations are different from those in FIG. Driving is performed to control the storage of DC power from the inverter circuit 21 to the storage battery 50 and the discharge of DC power from the storage battery 50 to the inverter circuit 21. Note that the control microcomputer 28 and the control PWM generation circuit 29 are control units in this embodiment. In other words, by rewriting the program of the control microcomputer, the motor drive and the power storage drive can be switched with the same basic configuration. Therefore, the control microcomputer may have a connection unit for communicating with an external computer, or the same microcomputer having a different program may be exchanged.

  Specifically, the A / D converter 27 inputs a current value flowing between each phase of the inverter circuit 21 and the storage battery 50, a terminal voltage value of the storage battery 50, and a DC power supply voltage value in the DC power supply line 10. . The A / D converter 27 digitizes this information and transmits it to the control microcomputer 28. Based on the charge / discharge instruction information input from the outside of the inverter module 20 and the information from the A / D converter 27, the control microcomputer 28 determines whether charging or discharging is provided to the inverter circuit 21. The driving signal to be determined is determined. The motor control PWM generation circuit 29 generates a drive signal (PWM signal) based on a command from the control microcomputer 28, and provides this drive signal to the base of each transistor of the inverter circuit 21.

  The multi-axis motor drive device 1 may include a control module including the control microcomputer 28 and the motor control PWM generation circuit 29 separately from the inverter module 20. Even with such a configuration, it is possible to suitably control the storage of DC power from the inverter circuit 21 to the storage battery 50 and the discharge of DC power from the storage battery 50 to the inverter circuit 21.

  FIG. 5 is a diagram schematically showing the operation of the inverter circuit 21 to which the coil unit 40 and the storage battery 50 are connected. In the following description, one phase of the three-phase inverters constituting the inverter circuit 21 will be representatively described, but the same applies to the other phases.

  First, when charging the storage battery 50, the negative side transistor of the inverter circuit 21 is fixed in the off state. At this time, since the diode is connected in reverse to the negative side transistor in parallel, the circuit shown in FIG. 5A is obtained. In such a state, the positive side transistor is intermittently turned on with a certain duty ratio, and the output is smoothed through the coil unit 40, whereby a DC power supply voltage corresponding to the duty ratio is generated, and the storage battery 50 Is charged. At this time, the duty ratio of the positive transistor is adjusted so that the terminal voltage of the storage battery 50 has a magnitude suitable for charging.

  Next, when discharging electric power from the storage battery 50, the positive side transistor of the inverter circuit 21 is fixed in an OFF state. At this time, since the diode is also connected in the reverse direction in parallel to the positive side transistor, a circuit as shown in FIG. 5B is obtained. In such a state, the negative transistor is intermittently turned on with a certain duty ratio, whereby the circuit including the coil unit 40 functions as a booster circuit, and the current from the storage battery 50 is discharged through the diode.

  The effect by the multi-axis motor drive device 1 of this embodiment is demonstrated. Normally, an inverter circuit used in an AC motor performs DC-AC conversion, but the present inventors can configure a DC-DC conversion circuit by connecting a coil to such an inverter circuit, and It was noted that the DC voltage value after conversion can be set arbitrarily by controlling the inverter circuit. That is, in the multi-axis motor drive device 1 of the present embodiment, the coil unit 40 is connected to the drive power output end 23 of a part of the N inverter modules 20 (M, M = 1 in the present embodiment). By connecting the storage battery 50, the terminal voltage value of the storage battery 50 can be set to an arbitrary magnitude by controlling the inverter circuit 21 regardless of the value of the DC power supply voltage VDC in the DC power supply line 10. Therefore, even when the DC power supply voltage VDC in the DC power supply line 10 is a relatively high voltage such as 140 [V] to 600 [V], the input voltage upper limit value in the specification of the storage battery 50 can be kept low. For example, it is possible to use a low-priced and small-sized battery such as DC24V, DC48V, or DC96V.

  In addition, it is possible to actively control the storage amount of the storage battery 50 by arbitrarily controlling the terminal voltage of the storage battery 50, and to operate the storage battery 50 with high efficiency, such as charging all the regenerative power to the storage battery 50. And a conventional regenerative resistor can be dispensed with. Furthermore, even if the surplus power suddenly increases, the terminal voltage of the storage battery 50 can be kept stable, so that regenerative power for a short time can be stored in the storage battery 50. Further, by monitoring the terminal voltage and charging / discharging current of the storage battery 50, it becomes possible to manage the amount of stored electricity and predict the life according to the type of the storage battery 50.

  Further, when many of the plurality of AC motors 60 are powered, the maximum load of the AC power supply P can be reduced by supplying DC power from the storage battery 50 to the DC power supply line 10. Therefore, it is sufficient to consider the effective load instead of the maximum load when selecting the device of the AC power source P, and the AC power source P can be downsized. Further, the AC motor 60 can be continuously operated by power supply from the storage battery 50 even during a power failure.

  Further, as in the present embodiment, the multi-axis motor driving device 1 controls the charging / discharging of the storage battery 50 by driving the inverter circuit 21 of the inverter module 20 to which the coil unit 40 and the storage battery 50 are connected. The microcomputer 28 and the motor control PWM generation circuit 29) are preferably provided. Thereby, the terminal voltage of the storage battery 50 can be suitably controlled to an arbitrary magnitude.

  Moreover, it is preferable that one end of the coil unit 40 is connected to the drive power output end 23 by a connector that can be attached to and detached from the drive power output end 23 of the inverter module 20 as in the present embodiment. Thus, by making the coil unit 40 detachable from the inverter module 20, the inverter module 20 for driving the AC motor 60 can be easily used for charge / discharge control of the storage battery 50.

  Further, as in the present embodiment, each inverter circuit 21 of the inverter module 20 may be configured by a three-phase inverter bridge. As a result, N inverter modules 20 are used for driving a three-phase AC motor, which is a general AC motor, and a part (M) of inverter modules 20 are used for charge / discharge control of the storage battery 50. Therefore, the cost can be reduced. Further, the coil unit 40 can be downsized by performing appropriate phase control.

  Further, as in the present embodiment, the multi-axis motor drive device 1 may include a power converter module 30 that converts the voltage from the AC power source P into the DC power source voltage VDC and supplies the DC power source line 10 with the voltage. Alternatively, the multi-axis motor drive device 1 may include a connector for connecting a rectifier that converts the voltage from the AC power supply P to the DC power supply voltage VDC and supplies the DC power supply line 10 to the DC power supply line 10. With any one of these configurations, the DC power supply voltage VDC can be suitably supplied to the DC power supply line 10.

  The multi-axis motor driving device according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above embodiment, a three-phase inverter bridge is exemplified as the inverter circuit. However, the inverter circuit of the present invention is not limited to this, and may be driven by one phase, or may be driven by more phases than three phases. Also good. The present invention can be applied to objects that require multi-axis control, such as robots, machine tools, stages, construction machines, and special vehicles. Furthermore, it is also suitable as a power supply device for a factory.

1 is a circuit diagram showing a configuration of an embodiment of a multi-axis motor driving device according to the present invention. It is a figure which shows an example of the structure for controlling the inverter circuit of the inverter module to which the AC motor was connected. (A), (b) It is a figure for demonstrating the production | generation method of the drive signal in the PWM generation circuit for motor control. It is a figure which shows an example of the structure for controlling the inverter circuit of the inverter module to which the coil unit and the storage battery were connected. It is a figure which shows typically (a) charge operation and (b) discharge operation of the inverter circuit to which the coil unit and the storage battery were connected.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multi-axis motor drive device, 10 ... DC power supply line, 20 ... Inverter module, 21 ... Inverter circuit, 22 ... Power supply input end, 23 ... Drive power output end, 24, 27 ... A / D converter, 25, 28 ... Control microcomputer, 26, 29 ... Buck-boost PWM generation circuit, 30 ... Power converter module, 40 ... Coil unit, 50 ... Storage battery, 60 ... AC motor, P ... AC power supply.

Claims (8)

A multi-axis motor drive device for driving a plurality of AC motors,
DC power line,
N inverter modules (N is an integer of 3 or more) having an inverter circuit for converting a DC power supply voltage from the DC power supply line into an AC power supply voltage and supplying the AC power supply voltage to each AC motor;
Each of the N inverter modules is
A power supply input terminal that is electrically connected to the DC power supply line and receives the DC power supply voltage;
A drive power output terminal that is electrically connected to each AC motor and supplies the AC power supply voltage to the AC motor;
Of the N inverter modules, a coil and a power storage unit are connected to the drive power output terminals of the M inverter modules (N−M ≧ 2 and M is an integer of 1 or more) instead of the AC motor. A multi-axis motor drive device characterized by that.   2. The multi-axis motor drive device according to claim 1, further comprising a controller that drives the inverter circuits of the M inverter modules to control charging and discharging of the power storage unit. Each of the N inverter modules has an integrated circuit for driving the inverter circuit,
The multi-axis motor driving device according to claim 2, wherein in the M inverter modules, the control unit is provided in the integrated circuit.   The multi-axis motor driving device according to claim 2, wherein a control module having the control unit is provided separately from the N inverter modules.   5. The multiplicity according to claim 1, wherein one end of the coil is connected to the drive power output end by a connector that can be attached to and detached from the drive power output end of the inverter module. Shaft motor drive device.   6. The multi-axis motor drive device according to claim 1, wherein each of the inverter circuits of the N inverter modules is configured by a three-phase inverter bridge.   The multi-axis motor driving device according to any one of claims 1 to 6, further comprising a rectifier that converts a voltage from an AC power source into the DC power source voltage and supplies the DC power source line to the DC power source line.   7. The connector according to claim 1, further comprising a connector for connecting a rectifier that converts a voltage from an AC power source into the DC power source voltage and supplies the DC power source line to the DC power source line. The multi-axis motor drive device according to one item.

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