JP3716520B2 - Electric vehicle motor drive control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for driving and controlling a traveling motor of an electric vehicle.
[0002]
[Prior art]
In the case of vehicle controllers and motor controllers equipped with microcomputers and memories, when data is not regularly written from the controller of the other party to the memory of each controller, or when the same data is continuously written for a predetermined time or more There is known a control device for an electric vehicle that determines that one of the controllers is abnormal and stops the operation of the device (see, for example, JP-A-5-122801).
[0003]
[Problems to be solved by the invention]
However, in the conventional electric vehicle control device described above, it takes time to determine the magnitude of the error of the output signal of each controller, and only by checking the data written in the memory and checking the transmitted / received data, There is a problem that it is not possible to check whether the motor is operating according to the command value by the control command value output by the motor controller.
[0004]
An object of the present invention is to provide a motor drive control device for an electric vehicle that quickly and surely determines a calculation result of a controller and determines the accuracy of motor drive control.
[0005]
[Means for Solving the Problems]
(1) The invention of claim 1 is an inverter that converts DC power supplied from a battery into AC power and applies it to a motor, and command value calculation means that calculates an output current command value of the inverter based on a torque command value. Current detection means for detecting the output current of the inverter, current feedback control based on the output current command value and the output current detection value, current control means for controlling the inverter, output current detection value Ifbk and output current When the difference (Ifbk−Iref) from the command value Iref becomes larger than the positive determination reference value Ith1, and the difference (Ifbk−Iref) is smaller than the negative determination reference value Ith2 (however, | Ith2 |> | Ith1 |) and stop control means for stopping the motor when it was, and a rotation speed detecting means for detecting a rotational speed of the motor in response to an increase of the rotational speed detection value, positive determine Reducing the negative determination reference value I th 2 with increasing the reference value I th 1.
(2) The invention of claim 2 is an inverter that converts DC power supplied from a battery into AC power and applies it to the motor, and first and first that calculate an output current command value of the inverter based on a torque command value. 2 command value calculation means, first and second current detection means for detecting the output current of the inverter, output current command value by the first command value calculation means, and output current detection value by the first current detection means The difference between the output current detection value Ifbk from the first control means for controlling the inverter and the second current detection means and the output current command value Iref from the second command value calculation means. When (Ifbk−Iref) becomes larger than the positive determination reference value Ith1, and the difference (Ifbk−Iref) is smaller than the negative determination reference value Ith2 (where | Ith2 |> | Ith1 |) And second control means for stopping the motor when Tsu, a rotation speed detecting means for detecting a rotational speed of the motor in response to an increase of the rotational speed detection value, increasing the positive determination reference value I th 1 At the same time, the negative determination reference value I th 2 is reduced .
(3) The motor drive control device for an electric vehicle according to claim 3 includes voltage detection means for detecting the DC link voltage of the inverter, and the determination reference values I th 1 and I th 2 according to a decrease in the DC link voltage detection value. It is intended to reduce this .
[0006]
【The invention's effect】
(1) According to the present invention, electrical on which it is possible to improve the reliability of the vehicle drive control device, such as immediately stopping the motor with respect to reduction of the motor current due to low battery voltage An erroneous determination can be avoided , and an accurate motor stop determination can be made in consideration of an increase in the error of the calculation of the motor drive control device and the control result as the motor rotation speed increases.
(2) According to the invention of claim 2, on which it is possible to improve the reliability of the motor Ta drive control device, an increase in the error of the arithmetic and control result of the motor drive control device associated with the increase in the motor rotation speed Considering this, an accurate motor stop determination can be made.
(3) According to the invention of claim 3 , since the determination reference values Ith1 and Ith2 are reduced according to the decrease of the DC link voltage detection value, the reduction of the motor current accompanying the decrease of the battery terminal voltage is taken into consideration. Thus, an accurate motor stop determination can be made.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
-First embodiment of the invention-
FIG. 1 is a diagram showing the configuration of the first embodiment.
The battery 1 supplies DC power to the inverter 4 via the inverter relay 2 and the DC link capacitor 3, and the inverter 4 converts the DC power into AC power and applies it to the three-phase induction motor 5. The inverter 4 is controlled by a torque processing controller 6 and a motor controller 7 that control the running of the electric vehicle. Two encoders 8 A and 8 B are mechanically connected to the motor 5, and both output a motor rotation angle signal to the motor controller 7. The voltage sensor 9 detects the DC link voltage Vd of the inverter 4 and outputs it to the motor controller 7. The current sensor 10 detects three-phase currents Iu, Iv, and Iw flowing through the motor 5 and outputs them to the motor controller 7.
[0008]
The torque processing controller 6 calculates a torque command based on an accelerator signal, a shift signal, a brake signal, a motor rotation speed, and the like, and outputs the torque command to the motor controller 7.
[0009]
The motor controller 7 is a control device for vector control of the inverter 4, calculates the output current command value of the inverter 4 based on the torque command value from the torque processing controller 6, and outputs the output current command value and encoders 8A and 8B. The PWM signal for driving the switching element of the inverter 4 is calculated based on the motor rotation angle signal from, the DC link voltage Vd from the voltage sensor 9, the motor currents Iu, Iv, Iw from the current sensor 10, and the like. The motor controller 7 also judges the magnitude of the error in the calculation result of the motor control command value and the actual motor control status, and outputs a stop command to the inverter 4 depending on the magnitude of the error and the motor control status. The relay 2 is opened to cut off the power supply to the inverter 4.
[0010]
FIG. 2 is a control block diagram of the motor controller 7.
The motor controller 7 includes a main microcomputer 11 (in this specification, the microcomputer is referred to as a microcomputer) 11, a sub-microcomputer 21, and an OR circuit 31. Each of the two microcomputers 11 and 21 calculates and compares the motor control command value, detects the magnitude of the error in the calculation result in the control command value calculation, and compares the motor control command value with the actual motor control result. Determine the motor control status. The motor controller 7 also calculates a motor rotation speed Nm based on the motor rotation angle signals from the encoders 8A and 8B, and outputs it to the vehicle controller 6.
[0011]
The main microcomputer 11 includes a motor control calculation unit 12, a coordinate conversion unit 13, a comparison unit 14, and a current control unit 15 configured in software form. The motor control calculation unit 12 is based on the torque command from the torque processing controller 6 and the motor rotation angle signal from the encoder 8A, and the torque current command value It ^* , the excitation current command value Im ^* , which is a motor control command value, The angle θm is calculated. The coordinate conversion unit 13 coordinates the motor currents Iu, Iv, Iw detected by the current sensor 10 to the feedback values It, Im of the torque current and the excitation current based on the motor electrical angle θm calculated by the motor control calculation unit 12. Convert (3/2 phase conversion). The comparison unit 14 includes motor control command values It ^* , Im ^* , θm calculated by the motor control calculation unit 12 and motor control command values Its ^* , Ims calculated by a motor control calculation unit 22 of the sub-microcomputer 21 described later. ^{* And} θs are individually compared, and if any of them is more than a predetermined value, a stop command is output to the OR circuit 31. The current control unit 15 performs current feedback control based on the motor control command values It ^* , Im ^* , θm and the current feedback values It, Im, and outputs a PWM signal to the inverter 4.
[0012]
The sub-microcomputer 21 includes a motor control calculation unit 22, a coordinate conversion unit 23, and a comparison unit 24 configured in software form. The motor control calculation unit 22 is based on the torque command from the torque processing controller 6 and the motor rotation angle signal from the encoder 8B, and the torque current command value Its ^* , the excitation current command value Ims ^* , which are motor control command values, The angle θs is calculated. The coordinate conversion unit 23 converts the motor currents Iu, Iv, Iw detected by the current sensor 10 based on the motor electrical angle θm calculated by the motor control calculation unit 12 of the main microcomputer 11 into a feedback value Its of the torque current and the excitation current. , Ims to coordinate conversion (3/2 phase conversion). The comparison unit 24 compares the motor control command values Its ^* and Ims ^* calculated by the motor control calculation unit 22 with the current feedback values Its and Ims converted by the coordinate conversion unit 23 and is calculated by the main microcomputer 11. The motor electrical angle θm and the motor electrical angle θs calculated by the sub-microcomputer 21 are compared, and if any of them has a difference of a predetermined value or more, a stop command is output to the OR circuit 31.
[0013]
FIG. 3 is a flowchart showing the processing of the main microcomputer 11, and FIG. 4 is a flowchart showing the processing of the sub-microcomputer 21. The operation of the first embodiment will be described with reference to these flowcharts.
The main microcomputer 11 repeatedly executes the process shown in FIG. 3 when the apparatus is turned on. In step 1, a torque current command value It ^* and an excitation current command value Im ^* are calculated based on the torque command and the motor rotation angle signal. Next, in step 2, the torque current command value Its ^* and the excitation current command value Ims ^* calculated by the sub-microcomputer 21 are input. In step 3, the torque current command values It ^* and Its ^* calculated by the two microcomputers 11 and 21 are individually compared with the excitation current command values Im ^* and Ims ^*, and the absolute value of the difference between the two is a predetermined value. It is confirmed whether it is smaller than ΔIt1, ΔIm1. In order to remove instantaneous fluctuations and noise included in the motor control command value, the motor control command value is subjected to low-pass filter processing and then subjected to comparison processing. If the difference between any of the current command values is greater than or equal to a predetermined value, it is determined that the error in the calculation results of the microcomputers 11 and 21 is large, the process proceeds to step 4 and a stop command is output to end the process.
[0014]
In this way, the same motor control command value is calculated and compared by two microcomputers, and if the difference is greater than or equal to a predetermined value, the apparatus is stopped because the error of the calculation results of the microcomputers 11 and 21 is large. Therefore, it is possible to quickly prevent the influence due to the error of the motor control command value, and to improve the reliability of the control device for the electric vehicle.
[0015]
If the current command values calculated by the two microcomputers 11 and 21 are both smaller than the predetermined value, it is determined that the error of the calculation results of the microcomputers 11 and 21 is extremely small, and the process proceeds to step 5. In step 5, the electrical angle θm of the motor 5 is calculated based on the motor rotation angle signal, and in the subsequent step 6, the motor electrical angle θs calculated by the sub-microcomputer 21 is input. In step 7, it is confirmed whether or not the absolute value of the difference between the motor electrical angles θm and θs calculated by the two microcomputers 11 and 21 is smaller than a predetermined value Δθ. In order to remove instantaneous fluctuations and noise included in the motor electrical angle signal, the motor electrical angle signal is subjected to low-pass filter processing and then subjected to comparison processing. If the difference in motor electrical angle is greater than or equal to a predetermined value, it is determined that the error in the calculation results of the microcomputers 11 and 21 is large, the process proceeds to step 8 and a stop command is output to end the process.
[0016]
In this way, the motor electrical angles are calculated and compared by the two microcomputers 11 and 21, and if the difference is equal to or larger than the predetermined value, the apparatus is stopped because the error of the calculation results of the microcomputers 11 and 21 is large. Therefore, it is possible to quickly prevent the influence due to the increase in the error of the motor electrical angle, and to improve the reliability of the control device for the electric vehicle.
[0017]
If the difference between the motor electrical angles calculated by the two microcomputers 11 and 21 is smaller than a predetermined value, it is determined that the error of the calculation results of the microcomputers 11 and 21 is extremely small, and the process proceeds to step 9. In step 9, the calculated motor electrical angle θm is output to the sub-microcomputer 21. In the next step 10, the three-phase motor currents Iu, Iv, and Iw are coordinate-converted into a torque current It and an exciting current Im based on the motor electrical angle θm, and a current feedback value is calculated. In step 11, current feedback control is performed based on the motor current command values It ^* and Im ^* and the current feedback values It and Im, and a PWM signal is calculated and output.
[0018]
The sub-microcomputer 21 repeatedly executes the process shown in FIG. 4 when the apparatus is powered on. In step 21, a torque current command value Its ^* and an excitation current command value Ims ^* are calculated based on the torque command and the motor rotation angle signal. In step 22, the motor electrical angle θm is input from the main microcomputer 11, and in step 23, the three-phase motor currents Iu, Iv, Iw are coordinate-converted into the torque current Its and the excitation current Ims by the motor electrical angle θm, and the current feedback value is obtained. Calculate.
[0019]
In step 24, the motor current command values Its ^* and Ims ^* and the current feedback values Its and Ims are individually compared, and it is determined whether or not the difference between the two is within the reference range as shown in Equation 1.
[Expression 1]
It21 <(Its−Its ^* ) <It22,
Im21 <(Ims-Ims ^* ) <Im22
Here, It21 and Im21 are negative determination reference values, It22 and Im22 are positive determination reference values,
[Expression 2]
| It21 | >> | It22 |,
| Im21 | >> | Im22 |
It is. In order to remove instantaneous fluctuations and noise included in the motor current command value and the current feedback value, the determination process of Formula 1 is performed after low-pass filter processing is performed on the motor current command value and the current feedback value. If the difference between the motor current command value and the current feedback value exceeds the reference range, it is determined that there is a large error between the computations and control results of the microcomputers 11 and 21, and the process proceeds to step 25 where a stop command is output and the process is terminated.
[0020]
In this way, the motor current command value and the current feedback value are compared, and if the difference exceeds a predetermined range, the apparatus is stopped because the error between the computations of the microcomputers 11 and 21 and the control result is large. The calculation and control result of the control device for the electric vehicle can be accurately determined, and the reliability of the device can be improved.
[0021]
As shown in Equation 2, the difference between the feedback values Its and Ims and the command values Its ^* and Ims ^* (Its−Its ^* ), ( Different values are set according to the sign of ⁽ Ims-Ims ^* ). In other words, the positive judgment reference value when a current larger than the command value flows is reduced and judged strictly, and conversely the negative judgment reference value when a current smaller than the command value flows increases and a large error occurs. Is acceptable.
[0022]
In electric vehicles, energy is supplied from the battery to the motor, so the remaining capacity of the battery decreases as it travels. If the terminal voltage decreases as the remaining capacity of the battery decreases, the current cannot be supplied by the command value even if feedback control of the output current is performed. In such a case, since there is no problem in the calculation and control by the drive control device, the running should not be stopped, and it is necessary to run to the charging station and quickly charge. In this embodiment, since the determination reference value when the feedback value of the motor current becomes smaller than the command value is increased, an erroneous determination that immediately stops running in response to a decrease in the motor current due to a decrease in the battery voltage. Can be avoided.
[0023]
In the above embodiment, the comparison determination reference value between the current feedback values Its and Ims and the command values Its ^* and Ims ^* is set to a constant value that is positive and negative, but the determination reference value is changed according to the motor rotation speed Nm. You may do it. For example, as shown in FIG. 5, when the motor rotation speed Nm increases, the positive determination reference values It22 ′ and Im22 ′ may be increased and the negative determination reference values It21 ′ and Im21 ′ may be decreased.
In general, as the rotation speed of the motor increases, the calculation and control errors of the control device increase, and the difference between the motor current command value and the actual current due to a decrease in battery voltage increases. By increasing and decreasing the positive and negative determination reference values according to the increase in the motor rotation speed, it is possible to avoid excessive travel stop determination.
[0024]
Since the motor electrical angle θ is calculated by integrating the motor rotation angle signals detected by the encoders 8A and 8B, even a slight error is integrated and becomes a large error. Therefore, in this embodiment, the motor electrical angle θm used for current feedback control in the main microcomputer 11 is also used for coordinate conversion processing on the sub-microcomputer 21 side. By performing processing using the same motor electrical angle θm with two microcomputers, the influence of the integration error can be eliminated, and the reliability of the apparatus can be improved.
[0025]
If the difference between the current feedback value and the motor current command value is within a predetermined range, it is determined that there is no abnormality in the apparatus, and the process proceeds to step 26. In step 26, the motor electrical angle θs is calculated based on the motor rotation angle signal, and in step 27, the motor electrical angle θm calculated by the main microcomputer 11 is input. In step 28, it is confirmed whether or not the absolute value of the difference between the motor electrical angles θs and θm calculated by the two microcomputers 11 and 21 is smaller than a predetermined value Δθ. If the absolute value of the motor electrical angle difference is greater than or equal to a predetermined value, it is determined that the error in the calculation results of the microcomputers 11 and 21 is large, the process proceeds to step 29, a stop command is output, and the process ends. If the motor electrical angle difference is smaller than the predetermined value, it is determined that the error in the calculation results of the microcomputers 11 and 21 is extremely small, and the process returns to step 21 to repeat the above processing.
[0026]
As described above, the motor electrical angle θm sent from the main microcomputer 11 and used for the coordinate conversion process is compared with the motor electrical angle θs calculated on the sub-microcomputer 21 side, and if the difference is equal to or larger than a predetermined value, the error is large. Since the apparatus is stopped, the reliability of the apparatus can be improved even when the value changes due to noise or the like during the transfer of the motor electrical angle θm from the main microcomputer 11 to the sub-microcomputer 21.
[0027]
In the configuration of the first and second embodiments described above, the battery 1 is the battery, the motor 5 is the motor, the inverter 4 is the inverter, the motor control calculation unit 22 is the command value calculation means, the current sensor 10 and the coordinates The conversion unit 23 constitutes current detection means, the current control part 15 constitutes current control means, the comparison part 24 constitutes stop control means, and the encoders 8A and 8B and the motor control calculation parts 12 and 22 constitute rotation speed detection means.
[0028]
In the first embodiment described above, the main microcomputer performs a feedback calculation based on the current command value and the current detection value, and the sub microcomputer compares the current command value and the current detection value to calculate and control the result. However, the feedback control, the calculation, and the determination of the control result may be performed by a single microcomputer.
[0029]
-Second embodiment of the invention-
In the first embodiment described above, the example in which the determination reference value is changed according to the magnitude of the current feedback value and the current command value is shown. However, the second determination reference value is changed according to the magnitude of the DC link voltage Vd. The embodiment will be described. The configuration of the second embodiment is the same as the configuration of the first embodiment shown in FIGS. 1 and 2, and the description thereof is omitted.
[0030]
FIG. 6 is a flowchart illustrating processing of the sub-microcomputer according to the second embodiment. The operation of the second embodiment will be described with reference to this flowchart. Note that steps that perform the same processing as the processing of the first embodiment shown in FIG.
In step 24A after calculating the motor current command values Its ^* and Ims ^* and the feedback values Its and Ims, the calculation reference value of the calculation and control result of the motor controller 9 according to the DC link voltage Vd detected by the voltage sensor 9 Set.
[0031]
Here, it is assumed that the negative determination reference value in the determination of the difference between the torque current feedback value Its and the command value Its ^* is It31, and the positive determination reference value is It32. In addition, a negative determination reference value for determining a difference between the excitation current feedback value Ims and the command value Ims ^* is Im31, and a positive determination reference value is Im32. These determination reference values It31, It32, Im31, and Im32 are reduced according to the decrease in the DC link voltage Vd.
[0032]
Since the DC link voltage Vd is substantially equal to the terminal voltage of the battery 1 during the power running operation of the inverter, the DC link voltage Vd decreases as the remaining capacity of the battery 1 decreases and the terminal voltage decreases. If the DC link voltage Vd decreases, it is impossible to pass current by the command value. However, as described above, in such a case, it is not a malfunction of the control device. Absent. Therefore, in the second embodiment, the determination reference values It31, It32, Im31, and Im32 are lowered as the DC link voltage Vd decreases. As a result, erroneous determinations such as immediately stopping traveling in response to a decrease in motor current due to a decrease in battery voltage can be avoided.
[0033]
In the above embodiment, the comparison determination reference value between the current feedback values Its and Ims and the command values Its ^* and Ims ^* is set to a constant value that is positive and negative, but the determination reference value is changed according to the motor rotation speed Nm. You may do it. For example, as shown in FIG. 7, when the motor rotation speed Nm increases, the positive determination reference values It32 ′ and Im32 ′ are increased and the negative determination reference values It31 ′ and Im31 ′ are decreased. Furthermore, the positive and negative determination reference values It31 ′, It32 ′, Im31 ′, and Im32 ′ are simultaneously reduced according to the decrease in the DC link voltage Vd.
As described above, in general, the higher the motor rotation speed, the greater the error between the calculation and control of the control device, and the greater the difference between the motor current command value and the actual current due to the decrease in battery voltage. By increasing and decreasing the positive and negative determination reference values according to the increase in the motor rotation speed, it is possible to avoid excessive travel stop determination.
[0034]
In the configuration of the second embodiment described above, the battery 1 is the battery, the motor 5 is the motor, the inverter 4 is the inverter, the motor control calculation unit 12 is the first command value calculation unit, and the motor control calculation unit 22 is used. Is the second command value calculation means, the current sensor 10 and the coordinate conversion section 13 are the first current detection means, the current sensor 10 and the coordinate conversion section 23 are the second current detection means, and the current control section 15 is the first. 1, the comparison unit 24 constitutes a second control unit, the encoders 8 </ b> A and 8 </ b> B and the motor control calculation units 12 and 22 constitute a rotation speed detection unit, and the voltage sensor 9 constitutes a voltage detection unit.
[0035]
In the first and second embodiments described above, since the apparatus is configured in the form of a microcomputer software without adding circuits and equipment, the reliability level of the apparatus with respect to the number of components can be reduced. Absent. However, it is of course possible to configure part or all of the control device in the form of hardware.
[0036]
In the first and second embodiments described above, an example in which a three-phase induction motor is used for the motor 5 and a vector control inverter is used for the motor controller 7 and the inverter 4 will be described. For example, a vector control inverter using a synchronous motor may be used.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first exemplary embodiment.
FIG. 2 is a control block diagram of the motor controller according to the first embodiment.
FIG. 3 is a flowchart showing processing of the main microcomputer of the first embodiment.
FIG. 4 is a flowchart showing processing of the sub-microcomputer according to the first embodiment.
FIG. 5 is a diagram illustrating a comparison determination reference value between a current command value and a current feedback value with respect to the motor rotation speed according to the first embodiment.
FIG. 6 is a flowchart illustrating processing of a sub-microcomputer according to the second embodiment.
FIG. 7 is a diagram illustrating a comparison determination reference value between a current command value and a current feedback value with respect to the motor rotation speed according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery 2 Inverter relay 3 DC link capacitor 4 Inverter 5 Motor 6 Torque processing controller 7 Motor controller 8A, 8B Encoder 9 Voltage sensor 10 Current sensor 11 Main microcomputer 12 Motor control calculation part 13 Coordinate conversion part 14 Comparison part 15 Current control part 21 Sub-microcomputer 22 Motor control operation unit 23 Coordinate conversion unit 24 Comparison unit 31 OR circuit

Claims (3)

An inverter that converts DC power supplied from the battery into AC power and applies it to the motor;
Command value calculating means for calculating an output current command value of the inverter based on a torque command value;
Current detection means for detecting the output current of the inverter;
Based on the output current command value and the output current detection value, current feedback control is performed, and current control means for controlling the inverter;
When the difference (Ifbk−Iref) between the output current detection value Ifbk and the output current command value Iref is larger than the positive determination reference value Ith1, and when the difference (Ifbk−Iref) is a negative determination reference value Ith2 (however, | Ith2 |> | Ith1 |) and stop control means for stopping said motor when more becomes smaller,
Rotation speed detection means for detecting the rotation speed of the motor,
A motor drive control device for an electric vehicle , wherein the positive determination reference value I th 1 is increased and the negative determination reference value I th 2 is decreased in accordance with an increase in the rotation speed detection value . An inverter that converts DC power supplied from the battery into AC power and applies it to the motor;
First and second command value calculation means for calculating an output current command value of the inverter based on a torque command value;
First and second current detection means for detecting an output current of the inverter;
First control means for performing current feedback control on the basis of an output current command value by the first command value calculation means and an output current detection value by the first current detection means, and for controlling the inverter;
When and when the difference (Ifbk−Iref) between the output current detection value Ifbk by the second current detection means and the output current command value Iref by the second command value calculation means is greater than the positive determination reference value Ith1 Second control means for stopping the motor when (Ifbk−Iref) becomes smaller than a negative determination reference value Ith2 (where | Ith2 |> | Ith1 |) ;
Rotation speed detection means for detecting the rotation speed of the motor,
A motor drive control device for an electric vehicle , wherein the positive determination reference value I th 1 is increased and the negative determination reference value I th 2 is decreased in accordance with an increase in the rotation speed detection value . In the electric vehicle motor drive control device according to claim 1 or 2,
Voltage detecting means for detecting a DC link voltage of the inverter;
A motor drive control device for an electric vehicle, wherein the determination reference values I th 1 and I th 2 are reduced according to a decrease in the DC link voltage detection value .

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