JP4365010B2 - Power output device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power output apparatus.
[0002]
[Prior art]
Conventionally, this type of power output device includes a capacitor connected to the positive and negative buses of an inverter circuit that applies three-phase alternating current to the motor, a positive or negative bus of the inverter circuit, and a neutral point of the motor. A device including a connected DC power source has been proposed (for example, Japanese Patent Laid-Open Nos. 10-337047 and 11-178114). In this device, a circuit composed of a coil of each phase of the motor and a switching element of each phase of the inverter is regarded as a boost chopper circuit that boosts the voltage of the DC power supply and stores electric charge in the capacitor, and uses the stored capacitor as the DC power supply. It is assumed that the motor is driven. The drive control of the motor and the storage control of the capacitor are simultaneously performed by the switching operation of the switching element of the inverter circuit when applying a pseudo three-phase alternating current to the motor.
[0003]
[Problems to be solved by the invention]
However, in such a power output device, an unexpected torque may be output from the electric motor at the time of starting. When the system is stopped, discharging is generally performed so that the residual voltage does not act on the capacitor from the viewpoints of durability and safety, and the power supply is generally shut off. When a DC power source is connected to start the power output device described above in a state where the DC power source is shut off while the capacitor is discharged, the DC power source is connected via a diode normally provided in each switching element of the inverter circuit. However, a circuit capable of charging the capacitor is formed, and a charging current flows. If the combined impedance consisting of each phase of the motor and each phase of the inverter circuit completely matches and the same current flows in each phase, the motor torque will not be output, but if the combined impedance does not match completely, each phase Different currents flow through the motor, and unexpected torque is generated from the motor.
[0004]
In addition, the discharge of the capacitor that is performed when the system is stopped is generally consumed by providing a discharge resistor in parallel with the capacitor. However, since the power is consumed as heat, the energy efficiency of the entire device is reduced. Resulting in.
[0005]
The power output device of the present invention has an object of preventing an unexpected torque output to the electric motor at the time of starting. Another object of the power output apparatus of the present invention is to start quickly. Furthermore, it is an object of the power output apparatus of the present invention to improve the energy efficiency of the apparatus. Alternatively, the power output device of the present invention is one of the purposes for downsizing and simplification of the device.
[0006]
[Means for solving the problems and their functions and effects]
The power output apparatus of the present invention employs the following means in order to achieve at least a part of the above object.
[0007]
The first power output apparatus of the present invention includes a power supply, a motor that rotates driven by polyphase alternating current, an inverter circuit capable of supplying a multi-phase AC power said motor by the switching operation of the multiple switching elements, before a connection means for serial the release of the power supply connection and connection with one of the bus of the positive bus and negative bus of the inverter circuit to the neutral point of the motor, positive bus and the negative bus before Symbol inverter circuit a rechargeable power storage means connected to the bets, when the startup instruction has been made, performing connection of the power supply by said connecting means after the beginning of the start switching control for a plurality of switching elements of the inverter circuit a time control means starts, wherein the startup switching control, the plurality of switching element so that the current flowing through each phase of the motor is equal The by switching, and summarized in that a control for charging the storage means with a current from the power supply.
[0008]
In the first power output apparatus of the present invention, when a start instruction is given, the start time control means starts the start time switching control for the plurality of switching elements of the inverter circuit, and then connects the power source by the connection means. Do. Therefore, since switching can be performed so that no torque is generated in the electric motor, unexpected torque can be prevented from being output from the electric motor, and a quick start can be performed.
[0009]
The second power output apparatus of the present invention includes a power supply, a motor that rotates driven by polyphase alternating current, an inverter circuit capable of supplying a multi-phase AC power said motor by the switching operation of the multiple switching elements, before A connecting means for connecting and disconnecting the power supply to a neutral point of the electric motor, and a positive bus and a negative bus of the inverter circuit; a rechargeable power storage means connected to the neutral point of the motor and generating line said power supply is not connected by the connecting means of, when the startup instruction has been made, the connection of the power supply by said connecting means and the and a start control module that performs a start-up time of switching control for a plurality of switching elements of the inverter circuit, the starting time of switching control, the electric By switching the plurality of switching elements so that the current flowing through each phase of the machine is equal to the gist of the control der Rukoto for charging the storage means with a current from the power supply.
[0010]
In the second power output apparatus of the present invention, when a start instruction is given, connection of power by the connecting means and switching control at start-up for a plurality of switching elements of the inverter circuit are performed. Therefore, since switching can be performed so that no torque is generated in the electric motor, unexpected torque can be prevented from being output from the electric motor, and a quick start can be performed.
[0011]
In the first or second power output apparatus of the present invention, the start-time switching control may be control for switching the plurality of switching elements so that torque is not output from the electric motor.
[0012]
Further, in the first or second power output apparatus of the present invention, the starting time of switching control, Ru control der for switching said plurality of switching elements so that current flowing through each phase of the motor are equal. In the first or second power output apparatus of the present invention according to this aspect, each phase current detecting means for detecting a current of each phase of the electric motor is provided, and the start-up control means is detected by each phase current detecting means. Control for switching the plurality of switching elements so that the electric motor and the power supply form a short circuit until the low state is released with respect to the phase having a low current value among the currents of the respective phases. It can also be a means for performing switching control at start-up.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described using examples. FIG. 1 is a configuration diagram showing an outline of the configuration of a power output apparatus 20 according to an embodiment of the present invention. As shown in the figure, the power output device 20 of the embodiment includes a motor 22 that is rotationally driven by three-phase AC, an inverter circuit 24 that can convert DC power to three-phase AC power and supply the motor 22, and an inverter circuit 24. The capacitor 30 connected to the positive electrode bus 26 and the negative electrode bus 28, the DC power source 32 connected via the relay 34 to the negative electrode bus 28 of the inverter circuit 24 and the neutral point of the motor 22, and the entire apparatus are controlled. Electronic control unit 40.
[0019]
The motor 22 is configured as a synchronous generator motor capable of generating electric power, for example, including a rotor having a permanent magnet attached to an outer surface and a stator wound with a three-phase coil. The rotating shaft of the motor 22 is an output shaft of the power output device 20 of the embodiment, and power is output from this rotating shaft. Since the motor 22 of the embodiment is configured as a generator motor, the motor 22 can generate power when power is input to the rotating shaft of the motor 22. Further, the DC power source 32 is configured as, for example, a nickel metal hydride or lithium ion secondary battery.
[0020]
The inverter circuit 24 includes six transistors T1 to T6 and six diodes D1 to D6. The six transistors T1 to T6 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus 26 and the negative electrode bus 28, respectively, and a three-phase coil (uvw) of the motor 22 is connected to the connection point. Each of which is connected. Therefore, if the on-time ratio of the transistors T1 to T6 that make a pair is controlled while a voltage is applied to the positive electrode bus 26 and the negative electrode bus 28, a rotating magnetic field is formed by the three-phase coil of the motor 22, and the motor 22 can be rotationally driven.
[0021]
The electronic control unit 40 is configured as a microprocessor centered on a CPU 42, and includes a ROM 44 that stores a processing program, a RAM 46 that temporarily stores data, and an input / output port (not shown). The electronic control unit 40 includes a current of each phase from the current sensors 52 to 56 attached to each phase of the uvw of the three-phase coil of the motor 22 and a current sensor 58 attached to the neutral point of the motor 22. The neutral point current, the rotation angle of the rotor of the motor 22 from the rotation angle sensor 60 attached to the rotation shaft of the motor 22, the voltage Vc between the terminals of the capacitor 30 from the voltage sensor 62 attached to the capacitor 30, the motor 22 The command value related to the operation is input through the input port. Further, from the electronic control unit 40, a control signal for performing switching control of the transistors T1 to T6 of the inverter circuit 24, a drive signal to the actuator 35 of the relay 34, and the like are output via an output port.
[0022]
Next, the operation of the power output apparatus 20 of the embodiment thus configured, particularly the operation at the time of starting will be described. FIG. 2 is a flowchart illustrating an example of a start time processing routine executed by the electronic control unit 40 of the power output apparatus 20 according to the embodiment at the time of start. This routine is executed when a start signal from a start switch (not shown) is input to the electronic control unit 40.
[0023]
When the start time process routine is executed, the CPU 42 of the electronic control unit 40 first executes a process for starting the inverter start time process (step S100). This inverter startup process is performed based on an inverter startup process routine illustrated in FIG. For ease of explanation, the inverter startup process will be described. In the inverter start-up process, first, the phase currents Iu, Iv, Iw detected by the current sensors 52 to 56 are read (step S110), and the minimum phase current among the read phase currents Iu, Iv, Iw is determined. (Step S112). Then, the transistor of the inverter circuit 24 is switched so as to be a short circuit for the phase corresponding to the minimum phase current (step S114), and the transistor of the inverter circuit 24 is switched so as to be a charging circuit for the other phases ( Step S116), this routine is finished. FIG. 4 shows a circuit diagram of the power output apparatus 20 of the embodiment focusing on the leakage inductance of the three-phase coil (u-phase) of the motor 22. The short circuit described above is a circuit indicated by a broken line arrow in the figure formed in a state where the transistor T2 of the inverter circuit 24 is turned on in consideration of the u phase, and the charging circuit turns off the transistor T2 of the inverter circuit 24. It is the circuit shown by the solid line arrow in the figure formed in the state. Since the v-phase and w-phase of the three-phase coil of the motor 22 are the same circuit as the u-phase, the state where the transistors T4 and T6 are turned on is a short circuit of the v-phase and w-phase, and the transistors T4 and T6 are turned off. This is the v-phase and w-phase charging circuits.
[0024]
The operation of the circuit of FIG. 4 constituting such a short circuit and a charging circuit will be described. In the short circuit, the u phase of the three-phase coil of the motor 22 functions as a reactor. When the transistor T2 is turned off from the short circuit state to form a charging circuit, the energy stored in the u phase of the three-phase coil functioning as a reactor is stored in the capacitor 30. At this time, the voltage Vc of the capacitor 30 can be made higher than the supply voltage of the DC power supply 32. Therefore, this circuit can be regarded as a boost chopper circuit that boosts and stores the energy of the DC power supply 32 in the capacitor 30. Here, the rising speed of the current in the short circuit is determined by the voltage of the DC power supply 32 and the inductance of the winding of the motor 22. On the other hand, the rising speed of the current in the charging current is initially the same as the rising speed of the short circuit, but the increasing speed of the current decreases as the voltage Vc between the terminals of the capacitor 30 increases. Therefore, the inverter start-up processing routine illustrated in FIG. 3 uses a short circuit for the phase corresponding to the minimum phase current and a charging circuit for the other phases, thereby reducing the minimum phase current. This is a process for increasing the rate of increase of the current of the phase higher than the rate of increase of the current of the other phase. By repeatedly executing this inverter start-up process routine, each phase current rises while showing substantially the same current value, and the capacitor 30 is charged.
[0025]
Returning to the startup processing routine of FIG. 2, when the inverter startup processing is started, the relay 34 is turned on (step S102), and the DC power supply 32 is connected to the negative electrode bus 28 and the neutral point of the motor 22. Before the relay 34 is turned on, each of the phase currents Iu, Iv, and Iw has a value of 0. Therefore, regardless of which phase is a short circuit or a charging circuit by the inverter start-up process, the capacitor 30 It cannot be charged and is in the same electrical state. When the relay 34 is turned on and the DC power source 32 is connected, values are generated in the phase currents Iu, Iv, and Iw. The values depend on the difference in the rising speed due to the length of the winding of each phase and the contact resistance of the connection point. There is a slight difference. The inverter startup processing routine functions based on the difference between the phase currents Iu, Iv, and Iw, and as described above, the phase currents Iu, Iv, Increase Iw as well. FIG. 5 shows an example of the increase in phase current. In the figure, the straight line A shows the change with respect to time of the phase current in the short circuit, the solid broken line B shows the change with respect to the time of the phase current by the process at the time of starting the inverter, and the broken line C shows the change with respect to the average of the phase current. As shown by a solid broken line B in the figure, the phase current repeatedly charges the capacitor 30 by the charging circuit and rises by the short circuit, and rises while slightly raising and lowering the average rising speed (broken line C).
[0026]
When the relay 34 is turned on, the inter-terminal voltage Vc of the capacitor 30 detected by the voltage sensor 62 is read (step S104), and a process of waiting for the inter-terminal voltage Vc to be equal to or higher than the threshold value Vr is executed (step S106). . Here, the threshold value Vr is a voltage of the capacitor 30 in a state where the driving of the motor 22 can be started by switching control of the transistors T1 to T6 of the inverter circuit 24, and is between the supply voltage of the DC power supply 32 and a voltage in the vicinity of twice that. Is set as the value of. When the inter-terminal voltage Vc of the capacitor 30 becomes equal to or higher than the threshold value Vr, the inverter start-up process is stopped (step S108), and the start-up process is terminated.
[0027]
According to the power output apparatus 20 of the embodiment described above, since the relay 34 is turned on and the DC power supply 32 is connected after starting the switching of the transistors T1 to T6 of the inverter circuit 24 by the inverter starting process, each phase of the motor 22 is connected. Initial charging of the capacitor 30 can be performed by increasing the currents Iu, Iv, and Iw evenly. Since the phase currents Iu, Iv, and Iw are increased uniformly, no torque is generated in the motor 22. As a result, it is possible to prevent unexpected torque from being generated in the motor 22.
[0028]
Next, the process at the time of the stop of the power output device 20 of an Example is demonstrated. FIG. 6 is a flowchart illustrating an example of a stop time processing routine executed by the electronic control unit 40 of the power output apparatus 20 according to the embodiment at the time of stop. This routine is executed when a stop signal from a stop switch (not shown) is input to the electronic control unit 40.
[0029]
When the stop processing routine is executed, the CPU 42 of the electronic control unit 40 first reads the inter-terminal voltage Vc of the capacitor 30 detected by the voltage sensor 62 (step S200), and the read inter-terminal voltage Vc is the DC power supply. The process which compares 32 with the voltage Vb which can be charged is performed (step S202). When the inter-terminal voltage Vc of the capacitor 30 is larger than the chargeable voltage Vb, a stop-time charging process for charging the DC power supply 32 using the potential of the capacitor 30 is performed (step S204), and the process returns to step S200. In the stop charging process, the transistors T1, T3, T5 on the positive bus 26 side of the inverter circuit 24 are turned on and the transistors T2, T4, T6 on the negative bus 28 side are turned off. This is performed by repeatedly executing the charging process routine. When the stop-time charging process routine is executed, the CPU 42 of the electronic control unit 40 reads each phase current Iu, Iv, Iw detected by the current sensors 52 to 56 (step S220), and each phase current Iu, Iv, The phase current of the maximum current of Iw is determined (step S222), and the transistor on the positive electrode bus 26 side is turned off for a predetermined time for the phase of the maximum phase current (step S224). Here, the predetermined time is shorter than the interval at which the stop-time charging process routine is repeated. By repeating this routine, the phase currents Iu, Iv, and Iw can be equalized. As a result, it is possible to prevent an unexpected torque from being output from the motor 22 during charging.
[0030]
When the inter-terminal voltage Vc of the capacitor 30 becomes equal to or lower than the chargeable voltage Vb, the relay 34 is turned off and the DC power supply 32 is shut off (step S206), and the electric charge remaining in the capacitor 30 is replaced with the circuit resistance of the inverter circuit 24 and the winding of the motor 22 Discharge during stop is performed due to wire resistance. For example, when this processing is consumed by the circuit resistance of the inverter circuit 24, the transistors T1 to T6 are repeatedly turned on and off to form a short circuit while controlling the current value, and consumed by the transistors T1 to T6 as heat. When consumed by the winding resistance of the motor 22, the transistors T1 to T6 of the inverter circuit 24 may be switched as a zero torque command. By setting the zero torque command, the phase currents Iu, Iv, Iw are equalized, and it is possible to prevent an unexpected torque from being output from the motor 22 during discharging.
[0031]
According to the power output device 20 of the embodiment described above, since the DC power supply 32 is charged by using a part of the charge of the capacitor 30 at the time of stop, the device is more than that which consumes all the charge of the capacitor 30 by the resistance. Energy efficiency can be improved. In addition, when a part of the electric charge of the capacitor 30 is consumed by the circuit resistance of the inverter circuit 24 or the winding resistance of the motor 22, the phase currents Iu, Iv, Iw are equalized, so that unexpected torque is output from the motor 22. Can be prevented.
[0032]
In the power output apparatus 20 of the embodiment, the DC power source 32 is attached so as to connect the negative bus 28 of the inverter circuit 24 and the neutral point of the motor 22 via the relay 34, but the positive power bus 26 of the inverter circuit 24 The DC power source 32 may be attached to the neutral point of the motor 22 via the relay 34.
[0033]
Further, in the power output device 20 of the embodiment, the capacitor 30 is attached so as to connect the positive electrode bus 26 and the negative electrode bus 28 of the inverter circuit 24, but as shown in the power output device 20B of the modification of FIG. The capacitor 30B may be attached so as to connect the positive bus 26 of the inverter circuit 24 and the neutral point of the motor 22. FIG. 9 is a circuit diagram of a modified power output apparatus 20 </ b> B focusing on the leakage inductance of the three-phase coil (u-phase) of the motor 22. In the power output device 20B of the modification, when considering the u phase, the short circuit is a circuit indicated by a broken line arrow formed in a state where the transistor T2 of the inverter circuit 24 is turned on, and the charging circuit is an inverter circuit. This is a circuit indicated by a solid line arrow formed in a state where 24 transistors T2 are turned off. Since the v-phase and w-phase of the three-phase coil of the motor 22 are the same circuit as the u-phase, the state where the transistors T4 and T6 are turned on is a short circuit of the v-phase and w-phase, and the transistors T4 and T6 are turned off. This is the v-phase and w-phase charging circuits. In the power output device 20B of this modification, when the relay 34 is turned on and the DC power supply 32 is connected, if the transistors T2, T4, T6 are all off, the charging current does not flow, and the power output device 20 of the embodiment. Although charging of the capacitor 30B is not immediately started as in the case of the above, in order to prevent the motor 22 from generating torque when the capacitor 30B is initially charged and to charge it, the same start as the power output device 20 of the embodiment Time processing is required. Specifically, the start time processing routine of FIG. 2 and the inverter start time processing routine of FIG. 3 are used as they are except that the threshold value Vr is set between the value 0 and a value near the voltage of the DC power supply 32. it can. Therefore, the power output apparatus 20B according to the modified example can also exhibit an effect at the time of starting in the power output apparatus 20 according to the embodiment, that is, an effect that can prevent an unexpected torque from being generated in the motor 22 when the capacitor 30B is charged. In the power output apparatus 20 of the modification, when stopped, the transistor T1 is turned on to form a short circuit in the capacitor 30B, the three-phase coil is made to function as a reactor, and the transistor T1 is turned off to use the reactor energy to generate a DC power supply. 32 can be charged. At this time, if the minimum or maximum of the phase currents Iu, Iv, Iw is determined and the transistors T1, T3, T5 are turned on / off, the phase currents Iu, Iv, Iw can be equalized. Also in the power output device 20B, the stop time processing routine of FIG. 6 and the stop time charging processing routine of FIG. 7 can be used as they are. Therefore, the power output apparatus 20B of the modified example also has an effect at the time of stopping in the power output apparatus 20 of the embodiment, that is, an effect of improving the energy efficiency of the apparatus and an effect of preventing an unexpected torque from being generated in the motor 22. Can do.
[0034]
In the power output device 20B of the modification, a capacitor 30B is attached so as to connect the positive bus 26 of the inverter circuit 24 and the neutral point of the motor 22, and the negative bus 28 of the inverter circuit 24 and the neutral point of the motor 22 are relayed. The DC power supply 32 is attached so as to be connected via the relay 34, but the DC power supply 32 is attached via the relay 34 between the positive bus 26 of the inverter circuit 24 and the neutral point of the motor 22, and the negative bus 28 of the inverter circuit 24 is attached. The capacitor 30B may be attached so as to connect the motor and the neutral point of the motor 22.
[0035]
In the power output apparatus 20 of the embodiment and its modification, the phase currents Iu, Iv, Iw are set by repeatedly executing the process of setting the phase of the minimum phase current in the short circuit and setting the other phases in the charging circuit. The phase currents Iu, Iv, and Iw are increased uniformly by repeating the process of setting the phase of the maximum phase current in the charging circuit and setting the other phases in the short circuit. It doesn't matter as a thing. This is because the phase current of the motor 22 can be increased uniformly, although it takes time to charge the capacitors 30 and 30B as compared with the power output device 20 of the embodiment.
[0036]
In the power output apparatus 20 of the embodiment and its modification, the synchronous generator motor driven by three-phase alternating current is used as the motor 22; however, any type of electric motor driven by multi-phase alternating current may be used.
[0037]
The embodiments of the present invention have been described using the embodiments. However, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the gist of the present invention. Of course you get.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of a configuration of a power output apparatus 20 according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an example of a start-up process routine executed by the electronic control unit 40 of the power output apparatus 20 according to the embodiment.
FIG. 3 is a flowchart illustrating an example of an inverter start-up processing routine executed by the electronic control unit 40 of the power output apparatus 20 according to the embodiment.
4 is a circuit diagram of the power output apparatus 20 of the embodiment focusing on the leakage inductance of the three-phase coil (u-phase) of the motor 22. FIG.
FIG. 5 is an explanatory diagram illustrating an increase in phase current.
FIG. 6 is a flowchart illustrating an example of a stop time processing routine executed by the electronic control unit 40 of the power output apparatus 20 according to the embodiment.
FIG. 7 is a flowchart illustrating an example of a stop-time charging process routine executed by the electronic control unit 40 of the power output apparatus 20 according to the embodiment.
FIG. 8 is a configuration diagram showing an outline of a configuration of a power output apparatus 20B according to a modification.
FIG. 9 is a circuit diagram of a modified power output apparatus 20B focusing on the leakage inductance of the three-phase coil (u phase) of the motor 22.
[Explanation of symbols]
20, 20B Power output device, 22 Motor, 24 Inverter circuit, 26 Positive bus, 28 Negative bus, 30, 30B Capacitor, 32 DC power supply, 34 Relay, 35 Actuator, 40 Electronic control unit, 42 CPU, 44 ROM, 46 RAM 52-58 Current sensor, 60 rotation angle sensor, 62 voltage sensor, T1-T6 transistor, D1-D6 diode.

Claims (4)

Power supply,
An electric motor that is rotationally driven by polyphase alternating current;
An inverter circuit capable of supplying multiphase AC power to the electric motor by switching operation of a plurality of switching elements;
Connecting means for connecting and releasing the connection of the power supply to the neutral point of the electric motor and any one of the positive bus and the negative bus of the inverter circuit;
Charge / discharge power storage means connected to the positive and negative buses of the inverter circuit;
A start time control means for connecting the power source by the connection means after starting the start time switching control for the plurality of switching elements of the inverter circuit when a start instruction is made;
With
The start-up switching control is a power output device that is a control for switching the plurality of switching elements so that currents flowing in the respective phases of the electric motor become equal, and charging the power storage means with current from the power source. Power supply,
An electric motor that is rotationally driven by polyphase alternating current;
An inverter circuit capable of supplying multiphase AC power to the electric motor by switching operation of a plurality of switching elements;
Connecting means for connecting and releasing the connection of the power supply to the neutral point of the electric motor and any one of the positive bus and the negative bus of the inverter circuit;
A chargeable / dischargeable power storage means connected to a busbar to which the power source is not connected by the connecting means and a neutral point of the inverter circuit among a positive busbar and a negative busbar of the inverter circuit;
A start time control means for performing connection of the power source by the connection means and start time switching control for a plurality of switching elements of the inverter circuit when a start instruction is given;
With
The start-up switching control is a power output device that is a control for switching the plurality of switching elements so that currents flowing in the respective phases of the electric motor become equal, and charging the power storage means with current from the power source.   3. The power output apparatus according to claim 1, wherein the start-time switching control is control for switching the plurality of switching elements so that torque is not output from the electric motor. 4. The power output device according to any one of claims 1 to 3,
Each phase current detection means for detecting the current of each phase of the electric motor,
The start-up control means is a short circuit between the electric motor and the power supply until the low state is released with respect to the phase of the low current value among the currents of the respective phases detected by the respective phase current detection means. A power output device which is means for performing control for switching the plurality of switching elements to form the switching control at the time of starting.

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