JP2010183673A - Vehicle driving device - Google Patents

Abstract

A vehicle drive device with improved controllability of a rotating electrical machine is provided.
A control device 30 is configured to switch a control mode of each of first and second rotating electrical machines MG1, MG2 from a rectangular wave voltage control mode to a non-rectangular wave voltage control mode when a voltage VH of a power supply node increases. Execute. Further, when both the control mode of the first rotating electrical machine MG1 and the control mode of the second rotating electrical machine MG2 are the rectangular wave voltage control mode, the control device 30 determines the rotational speed MRN1 of the first rotating electrical machine MG1 and the first When the difference from the rotational speed MRN2 of the second rotating electrical machine MG2 becomes smaller than the threshold value, the control mode of either the first or second rotating electrical machine MG1, MG2 changes to the non-rectangular wave voltage control mode. Until then, the voltage converter 12 is controlled to increase the voltage VH of the power supply node.
[Selection] Figure 1

Description

  The present invention relates to a vehicle drive device, and more particularly, to a vehicle drive device that performs first and second rotating electrical machines used for driving a vehicle by switching control between a rectangular wave voltage control mode and a non-rectangular wave voltage control mode.

  Japanese Patent Laid-Open No. 2003-244990 (Patent Document 1) generates an intermediate-wave AC voltage obtained by synthesizing a sine wave and a rectangular wave and applies it to the motor when switching between sine wave driving and rectangular wave driving of the motor. The technology to do is disclosed.

  Even in an electric vehicle or a hybrid vehicle, a motor control mode may be selected from a rectangular wave voltage control mode and a non-rectangular wave voltage control mode to determine the control mode and control the motor.

JP 2003-244990 A JP 2007-166875 A

  There is a vehicle equipped with a vehicle drive device including two rotating electrical machines such as a motor and a generator. The two rotating electrical machines are referred to as motor generators MG1 and MG2. In order to provide them, the voltage of a DC power source such as a battery may be boosted to generate a boosted voltage VH and supplied to the drive inverters of motor generators MG1 and MG2.

  Conventionally, the capacity of the smoothing capacitor for smoothing the boosted voltage VH is large and the fluctuation of the boosted voltage VH is not so large. Therefore, the motor generators MG1 and MG2 are both controlled by a rectangular wave, and the rotational speeds of both are the same. Even if it did not affect the controllability in particular. However, if the cost is reduced and the capacity of the smoothing capacitor is reduced, the boosted voltage VH tends to fluctuate. As a result, when motor generators MG1 and MG2 are in the rectangular wave voltage control and at the same rotation speed, the currents of motor generators MG1 and MG2 may be disturbed due to fluctuations in boosted voltage VH.

  FIG. 6 is an operation waveform diagram showing a situation where both motor generators MG1 and MG2 are controlled in the rectangular wave voltage control mode and the rotation speed is the same.

  Referring to FIG. 6, the vertical axis shows boosted voltage VH, motor generator MG1 phase voltage, and motor generator MG2 phase voltage. The horizontal axis shows the passage of time. As described above, there may occur a case where the electrical cycle T1 of the motor generator MG1 is equal to the electrical cycle T2 of the motor generator MG2. Even in this state, there is no problem unless there is an electrical primary power fluctuation factor.

  However, when the power of motor generator MG2 fluctuates in electrical primary under the influence of current sensor error or resolver error of motor generator MG2, the boosted voltage VH also fluctuates synchronously as a result. Furthermore, since the fluctuation cycle of boosted voltage VH matches the electrical cycle of motor generator MG1, the current of motor generator MG1 is disturbed.

  FIG. 7 is an operation waveform diagram showing disturbance of boosted voltage VH and phase voltage and current of motor generator MG1.

  As shown in FIG. 7, when an electric primary fluctuation occurs in motor generator MG2 due to an offset error or a resolver error of the current sensor, boosted voltage VH similarly changes in the electric primary. When a rectangular wave voltage is generated using this boosted voltage VH, the voltage of the phase voltage of motor generator MG1 becomes unbalanced up and down. Then, as a result, an offset is generated in the current of motor generator MG1, and further the power fluctuation of motor generator MG1 is caused.

  As a result, fluctuations in the boost voltage VH can affect the controllability of the motor generator.

  An object of the present invention is to provide a vehicle drive device with improved controllability of a rotating electrical machine.

  In summary, the present invention is a vehicle drive device, and is provided with first and second rotating electrical machines used for driving a vehicle and first and second rotating electrical machines provided corresponding to the first and second rotating electrical machines, respectively. Inverter, a smoothing capacitor connected to a common power supply node of the first and second inverters, a voltage converter for converting the power supply voltage from the DC power supply and applying it to the power supply node, and the first and second inverters And a control device for controlling the voltage converter. The control device executes control to switch the control mode of each of the first and second rotating electrical machines from the rectangular wave voltage control mode to the non-rectangular wave voltage control mode when the voltage of the power supply node increases. Further, the control device is configured such that when both the control mode of the first rotating electrical machine and the control mode of the second rotating electrical machine are the rectangular wave voltage control mode, the rotational speed of the first rotating electrical machine and the second rotating electrical machine are controlled. When the difference from the rotational speed becomes smaller than the threshold value, the voltage converter is controlled until the control mode of either the first or second rotating electrical machine changes to the non-rectangular wave voltage control mode, and the power supply node Increase the voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the controllability of a rotary electric machine is improved in a vehicle drive device.

1 is a circuit diagram showing a configuration of a vehicle according to an embodiment of the present invention. It is the figure which showed how the control mode was determined in a certain boosting voltage. 2 is a flowchart for illustrating control of a boost converter executed by control device 30 of FIG. 1. It is the flowchart which showed the detail of the process of step S8 of FIG. FIG. 4 is a diagram for explaining that the boosted voltage VH increases as a result of the process of step S8 of FIG. 3 and the control mode is changed from the rectangular wave voltage control mode to the non-rectangular wave voltage control mode. FIG. 11 is an operation waveform diagram showing a situation when both motor generators MG1 and MG2 are controlled in the rectangular wave voltage control mode and the rotation speed is the same. FIG. 10 is an operation waveform diagram showing disturbance of boosted voltage VH and phase voltage and current of motor generator MG1.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

FIG. 1 is a circuit diagram showing a configuration of a vehicle according to an embodiment of the present invention.
Referring to FIG. 1, vehicle 100 includes a battery unit 40, an engine 4, motor generators MG <b> 1 and MG <b> 2, a power split mechanism 3, wheels 2, and a control device 30.

  Power split device 3 is a mechanism that is coupled to engine 4 and motor generators MG1 and MG2 and distributes power between them. For example, as the power split mechanism, a planetary gear mechanism having three rotating shafts of a sun gear, a planetary carrier, and a ring gear can be used. These three rotation shafts are connected to the rotation shafts of engine 4 and motor generators MG1, MG2, respectively. For example, the motor generator MG1, the power split mechanism 3, the motor generator MG1, and the engine 4 can be arranged on a straight line by hollowing the rotating shaft of the motor generator MG1 and passing the power shaft of the engine 4 therethrough.

  The rotating shaft of motor generator MG2 is coupled to wheel 2 by a reduction gear or a differential gear (not shown). Further, a reduction gear for the rotation shaft of motor generator MG2 may be further incorporated in power split device 3.

  Battery unit 40 includes a high voltage battery B1, a system main relay SMRG connected to the negative electrode of high voltage battery B1, and a system main relay SMRB connected to the positive electrode of high voltage battery B1. System main relays SMRG and SMRB are controlled to be in a conductive / non-conductive state in response to a control signal SE provided from control device 30.

  As the high voltage battery B1, a secondary battery such as nickel metal hydride or lithium ion, a fuel cell, or the like can be used.

  The battery unit 40 further measures a service plug SP that cuts off the high voltage when the service cover is opened, a fuse F connected to the high voltage battery B1 in series with the service plug SP, and a voltage VB between the terminals of the high voltage battery B1. A voltage sensor 10 that detects the current IB that flows through the high-voltage battery B1.

  Vehicle 100 further includes a smoothing capacitor C1 connected between power supply line PL1 and ground line SL, a voltage sensor 21 that detects voltage VL between both ends of smoothing capacitor C1 and outputs the same to control device 30, and a smoothing Boost converter 12 that boosts the voltage between terminals of capacitor C1, smoothing capacitor C2 that smoothes the voltage boosted by boost converter 12, and voltage that is output to control device 30 by detecting voltage VH between terminals of smoothing capacitor C2. Sensor 13 and inverter 14 that converts the DC voltage applied from boost converter 12 into a three-phase AC and outputs the same to motor generator MG1 are included.

  Boost converter 12 is connected in parallel to reactor L1 having one end connected to power supply line PL1, IGBT elements Q1 and Q2 connected in series between power supply line PL2 and ground line SL, and IGBT elements Q1 and Q2. Diodes D1 and D2.

  Reactor L1 has the other end connected to the emitter of IGBT element Q1 and the collector of IGBT element Q2. The cathode of diode D1 is connected to the collector of IGBT element Q1, and the anode of diode D1 is connected to the emitter of IGBT element Q1. The cathode of diode D2 is connected to the collector of IGBT element Q2, and the anode of diode D2 is connected to the emitter of IGBT element Q2.

  Inverter 14 receives the boosted voltage from boost converter 12, and drives motor generator MG1 to start engine 4, for example. Inverter 14 returns the electric power generated by motor generator MG 1 by mechanical power transmitted from engine 4 to boost converter 12. At this time, boost converter 12 is controlled by control device 30 to operate as a step-down circuit.

  Inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are connected in parallel between power supply line PL2 and ground line SL.

  U-phase arm 15 includes IGBT elements Q3 and Q4 connected in series between power supply line PL2 and ground line SL, and diodes D3 and D4 connected in parallel with IGBT elements Q3 and Q4, respectively. The cathode of diode D3 is connected to the collector of IGBT element Q3, and the anode of diode D3 is connected to the emitter of IGBT element Q3. The cathode of diode D4 is connected to the collector of IGBT element Q4, and the anode of diode D4 is connected to the emitter of IGBT element Q4.

  V-phase arm 16 includes IGBT elements Q5 and Q6 connected in series between power supply line PL2 and ground line SL, and diodes D5 and D6 connected in parallel with IGBT elements Q5 and Q6, respectively. The cathode of diode D5 is connected to the collector of IGBT element Q5, and the anode of diode D5 is connected to the emitter of IGBT element Q5. The cathode of diode D6 is connected to the collector of IGBT element Q6, and the anode of diode D6 is connected to the emitter of IGBT element Q6.

  W-phase arm 17 includes IGBT elements Q7 and Q8 connected in series between power supply line PL2 and ground line SL, and diodes D7 and D8 connected in parallel with IGBT elements Q7 and Q8, respectively. The cathode of diode D7 is connected to the collector of IGBT element Q7, and the anode of diode D7 is connected to the emitter of IGBT element Q7. The cathode of diode D8 is connected to the collector of IGBT element Q8, and the anode of diode D8 is connected to the emitter of IGBT element Q8.

  Motor generator MG1 is a three-phase permanent magnet synchronous motor, and one end of each of three coils of U, V, and W phases is connected to the midpoint. The other end of the U-phase coil is connected to the connection node of IGBT elements Q3 and Q4. The other end of the V-phase coil is connected to a connection node of IGBT elements Q5 and Q6. The other end of the W-phase coil is connected to a connection node of IGBT elements Q7 and Q8.

  Current sensor 24 detects the current flowing through motor generator MG1 as motor current value MCRT1, and outputs motor current value MCRT1 to control device 30.

  Vehicle 100 further includes an inverter 22 connected to boost converter 12 in parallel with inverter 14.

  Inverter 22 converts the DC voltage output from boost converter 12 into a three-phase AC and outputs the same to motor generator MG2 driving wheel 2. Inverter 22 returns the electric power generated in motor generator MG2 to boost converter 12 along with regenerative braking. At this time, boost converter 12 is controlled by control device 30 so as to operate as a step-down circuit. Although the internal configuration of inverter 22 is not shown, it is the same as inverter 14, and detailed description will not be repeated.

  Resolvers 26 and 27 detect motor rotation speeds MRN1 and MRN2 of motor generators MG1 and MG2, respectively, and send the detected motor rotation speeds MRN1 and MRN2 to control device 30. In addition, about these resolvers, you may abbreviate | omit arrangement | positioning by calculating motor rotation speed directly from a motor voltage and an electric current in the control apparatus 30. FIG.

  Vehicle 100 further includes auxiliary equipment 52 such as a headlamp, 12V auxiliary battery B2, and DC / DC converter 50 connected between power line PL1, auxiliary battery B2, and auxiliary equipment 52. including.

  The DC / DC converter 50 can step down the voltage of the power supply line PL2 in accordance with the step-down instruction PWD2 given from the control device 30, and charge the auxiliary battery B2 or supply electric power to the auxiliary devices 52. It is. DC / DC converter 50 can also boost the voltage of auxiliary battery B2 in accordance with boost instruction PWU2 provided from control device 30, and supply the boosted voltage to power supply line PL2.

  Control device 30 receives torque command values TR1, TR2, motor rotation speeds MRN1, MRN2, voltages VB, VL, VH, current IB values, motor current values MCRT1, MCRT2, and start signal IGON.

  Control device 30 outputs control signal PWU1 for instructing boosting to boost converter 12, control signal PWD1 for instructing step-down, and signal CSDN for instructing prohibition of operation.

  Control device 30 also outputs control signal PWU2 for instructing boosting to DC / DC converter 50 and control signal PWD2 for instructing step-down.

  Further, control device 30 provides to inverter 14 a drive instruction PWMI1 for converting a DC voltage that is the output of boost converter 12 into an AC voltage for driving motor generator MG1, and an AC voltage generated by motor generator MG1. Is converted to a DC voltage and a regenerative instruction PWMC1 is returned to the boost converter 12 side.

  Similarly, control device 30 converts to inverter 22 a drive instruction PWMI2 for converting a DC voltage into an AC voltage for driving motor generator MG2, and converts the AC voltage generated by motor generator MG2 into a DC voltage for boosting. A regeneration instruction PWMC2 to be returned to the converter 12 side is output.

  In a motor drive system that drives and controls an AC motor such as motor generators MG1 and MG2 by converting a DC voltage as shown in FIG. 1 into an AC voltage by an inverter, generally, the AC motor is driven with high efficiency. The motor current is often controlled according to sinusoidal PWM (Pulse Width Modulation) control based on vector control.

  However, in the sine wave PWM control mode, the fundamental wave component of the output voltage of the inverter cannot be sufficiently increased, and the voltage utilization rate is limited, so that it is difficult to obtain a high output in a region where the rotation speed is high. There is. In consideration of this point, the use of a modulation method capable of outputting a voltage having a higher fundamental wave component than the sine wave PWM control mode has been proposed.

  For example, in a control configuration (hereinafter also referred to as “rectangular wave voltage control mode”) in which a rectangular wave voltage is applied to an AC motor in order to improve output in a high rotation range, this AC motor is rotationally driven (hereinafter also referred to as “rectangular wave voltage control mode”). It has been proposed to control the torque of an AC motor by controlling the phase of this rectangular wave voltage based on the deviation between the actual torque and the actual torque.

  It has also been proposed to further employ an “overmodulation PWM control mode” that uses a voltage waveform intermediate between the rectangular wave voltage control mode and the sine wave PWM control mode. In the vehicle drive device in the present embodiment, the three control modes of sine wave PWM control, overmodulation PWM control, and rectangular wave voltage control are appropriately switched depending on the modulation factor.

  The sine wave PWM control mode is used as a general PWM control, and on / off of the switching element in each phase arm is compared with a voltage between a sine wave voltage command value and a carrier wave (typically a triangular wave). Control according to. As a result, for a set of a high level period corresponding to the on period of the upper arm element and a low level period corresponding to the on period of the lower arm element, the duty is set so that the fundamental wave component becomes a sine wave within a certain period. The ratio is controlled. As is well known, in the sine wave PWM control mode, the effective value ratio (modulation factor) of the fundamental wave component to the inverter DC input voltage can only be increased up to 0.61 times.

  On the other hand, in the rectangular wave voltage control mode, one pulse of a rectangular wave whose ratio between the high level period and the low level period is 1: 1 is applied to the AC motor within the predetermined period. As a result, the modulation rate is increased to 0.78.

  In the overmodulation PWM control mode, the same PWM control as the sine wave PWM control mode is performed after distorting the carrier wave to reduce the amplitude. As a result, the fundamental wave component can be distorted, and the modulation factor can be increased to a range of 0.61 to 0.78.

  In an AC motor, the induced voltage increases as the rotational speed and output torque increase, and the required voltage increases. The boosted voltage by boost converter 12, that is, system voltage VH, needs to be set higher than this motor required voltage (induced voltage). On the other hand, there is a limit value (VH maximum voltage) in the boosted voltage by boost converter 12, that is, system voltage VH.

  Therefore, in the region where the required motor voltage (induced voltage) is lower than the maximum value (VH maximum voltage) of the system voltage VH, the maximum torque control by the sine wave PWM control mode or the overmodulation PWM control mode is applied, and the vector control is followed. The output torque is controlled to the torque command value by the motor current control.

  On the other hand, when the required motor voltage (induced voltage) reaches the maximum value (VH maximum voltage) of the system voltage VH, the rectangular wave voltage control mode according to the field weakening control is applied while maintaining the system voltage VH. In the rectangular wave voltage control mode, since the amplitude of the fundamental wave component is fixed, the voltage of the rectangular wave pulse based on the deviation between the actual torque value obtained from the dq axis current value used in power calculation or vector control and the torque command value Torque control is executed by phase control.

  FIG. 2 is a diagram showing how the control mode is determined at a certain boosted voltage.

  As shown in FIG. 2, the sinusoidal PWM control mode is used in the low rotational speed range A1 to reduce the torque fluctuation, the overmodulation PWM control mode is used in the middle rotational speed range A2, and the rectangular shape is used in the high rotational speed range A3. Wave voltage control mode is applied. In particular, by applying the overmodulation PWM control mode and the rectangular wave voltage control mode, the output of the AC motor can be improved in the middle and high rotation ranges. As described above, which one of the control modes is used is determined within the range of the realizable modulation rate.

  FIG. 3 is a flowchart for explaining control of the boost converter executed by control device 30 of FIG.

  Referring to FIGS. 1 and 3, when processing is first started, control device 30 obtains rotation speed MRN1 of motor generator MG1 and torque command value TR1 of motor generator MG1 in step S1.

  In step S2, control device 30 searches for a predetermined voltage command map based on rotational speed MRN1 and torque TR1, and determines boosted voltage candidate VH1.

  Subsequently, in step S3, control device 30 acquires rotational speed MRN2 of motor generator MG2 and torque command value TR2 of motor generator MG2.

  In step S4, control device 30 searches for a predetermined voltage command map using rotation speed MRN2 and torque command value TR2, and determines boosted voltage candidate VH2.

  In step S5, control device 30 selects the higher one of boosted voltage candidates VH1 and VH2 and sets it to boosted voltage command value VH.

  In step S6, control device 30 determines a control mode of motor generator MG1 based on the modulation factor. In step S7, control device 30 similarly determines the control mode of motor generator MG2 based on the modulation factor.

  Subsequently, in step S8, a correction determination process for the boosted voltage VH is executed. This correction determination process will be described in detail with reference to FIG.

  Then, when corrected boosted voltage VH is determined in step S8, control device 30 controls boost converter 12 so as to generate boosted voltage VH, and performs boosting in step S9.

Thereafter, in step S10, control is transferred to the main routine.
FIG. 4 is a flowchart showing details of the process in step S8 of FIG.

  Referring to FIG. 4, when the process of step S8 is started, it is first determined in step S101 whether or not the mode of motor generator MG1 is a rectangular wave voltage control mode. If the control mode of motor generator MG1 is the rectangular wave voltage control mode in step S101, the process proceeds to step S102. If not, the process proceeds to step S105.

  In step S102, control device 30 determines whether or not the control mode of motor generator MG2 is the rectangular wave voltage control mode.

  In step S102, if the control mode of motor generator MG2 is the rectangular wave voltage control mode, the process proceeds to step S103, and if not, the process proceeds to step S105.

  In step S103, it is determined whether or not rotation speed MRN1 of motor generator MG1 is substantially equal to rotation speed MRN2 of motor generator MG2. This may be determined based on whether or not the difference between the rotational speeds MRN1 and MRN2 is equal to or less than a predetermined threshold value. If it is determined in step S103 that the rotation speeds of motor generators MG1 and MG2 are substantially equal, the process proceeds to step S104, and if it is not determined that they are approximately equal, the process proceeds to step S105.

  In step S104, control device 30 increases boosted voltage VH (for example, adds 5 V). When the process of step S104 ends, the process proceeds to step S105. In step S105, control is transferred to step S9 in FIG.

  By repeatedly executing the process of FIG. 4, when both control modes of motor generators MG1 and MG2 are rectangular wave voltage control, boosted voltage VH increases until one of them is not in rectangular wave voltage control mode. Will be.

  FIG. 5 is a diagram for explaining that the boosted voltage VH increases as a result of the process of step S8 of FIG. 3, and the control mode is changed from the rectangular wave voltage control mode to the non-rectangular wave voltage control mode.

  Referring to FIG. 5, when voltage VH that is the output voltage of boost converter 12 is VH1, as shown in solid line map A, sinusoidal PWM control mode, medium rotation speed region in low rotation speed region A1. The overmodulation PWM control mode is used in A2, and the rectangular wave voltage control mode is used in the high rotation speed range A3.

  On the other hand, when the voltage VH is VH2 lower than VH1, the low rotational speed region B1 is a sine wave PWM control mode, and the middle rotational speed region B2 is an overmodulation PWM control mode, as shown by a broken-line map B. In the high rotation speed region B3, the rectangular wave voltage control mode is used.

  Such a map is determined for each voltage VH and stored in advance in a memory built in the control device 30.

  That is, even when the rotation speed and the torque are in the same region, the control mode applied differs depending on how much the boost voltage VH of the boost converter 12 is set. For example, region Y in FIG. 5 belongs to region B3 when the boosted voltage VH = VH2, and the rectangular wave voltage control mode is applied. On the other hand, when the boosted voltage rises to the boosted voltage VH = VH1, the region Y belongs to the region A1 and the sine wave PWM control mode is applied. That is, by raising boosted voltage VH, one of motor generators MG1 and MG2 controlled in the rectangular wave voltage control mode is changed to be controlled in non-rectangular wave voltage control mode. As a result, the problem described with reference to FIGS. 6 and 7 does not occur, and the controllability of the motor is improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2 wheel, 3 power split mechanism, 4 engine, 10, 13, 21 voltage sensor, 11, 24, 25 current sensor, 12 boost converter, 14, 22 inverter, 15 U phase arm, 16 V phase arm, 17 W phase arm , 26, 27 Resolver, 30 Control device, 40 Battery unit, 50 DC / DC converter, 52 Auxiliary machinery, 100 Vehicle, B1 High voltage battery, B2 Auxiliary battery, C1, C2 Smoothing capacitor, D1-D8 diode, F fuse , L1 reactor, MG1, MG2 motor generator, PL1, PL2 power line, Q1-Q8 IGBT element, SL ground line, SMRG, SMRB system main relay, SP service plug.

Claims (1)

First and second rotating electric machines used for driving the vehicle;
First and second inverters provided respectively corresponding to the first and second rotating electrical machines;
A smoothing capacitor connected to a common power supply node of the first and second inverters;
A voltage converter that converts a power supply voltage from a DC power supply and applies the voltage to the power supply node;
A control device for controlling the first and second inverters and the voltage converter;
The control device executes control to switch the control mode of each of the first and second rotating electrical machines from the rectangular wave voltage control mode to the non-rectangular wave voltage control mode when the voltage of the power supply node increases,
When the control mode of the first rotating electrical machine and the control mode of the second rotating electrical machine are both in the rectangular wave voltage control mode, the control device determines the rotational speed of the first rotating electrical machine and the first rotating electrical machine. When the difference between the rotational speeds of the two rotating electrical machines becomes smaller than the threshold value, the control mode of either the first or second rotating electrical machine changes to the non-rectangular wave voltage control mode. A vehicle drive device that controls a voltage converter to increase a voltage of the power supply node.

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