JP2006121815A - Drive device of dc brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control means for a DC brushless motor that can surely stop a rotor at a prescribed position when the motor is rotated by an external force. <P>SOLUTION: This drive device of the DC brushless motor comprises: the DC brushless motor 1 and one magnetic pole position sensor 2 that detects the magnetic position of the rotor of the DC brushless motor; an inverter circuit 3 to which a plurality of switching elements are connected in a manner of three-phase bridging, converts a DC voltage 4 into an AC voltage by opening and closing the switching elements, and feeds the AC voltage to the DC brushless motor; and the control means 10 that opens and closes the switching elements on the basis of an output signal of the magnetic pole position sensor. By switching two DC magnetization patterns at the prescribed magnetic pole position by using the control means 10, the DC brushless motor can surely be braked and stopped without applying excessive loads to a drive circuit and the motor even if a fan is rotated by an external factor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a driving device for a DC brushless motor.

  Conventionally, DC brushless motors are often used to drive outdoor fans of air conditioners. The outdoor fan rotates when there is wind, and the rotation direction and speed are not uniform. If the motor is started in the rotation state, depending on the rotation direction and rotation speed, the motor may be heavily loaded and may be damaged. is there.

  Therefore, if the outdoor fan is rotating at the start of operation of the air conditioner, the air conditioner is started after braking, stopping, and positioning.

  On the other hand, the DC brushless motor uses a magnetic pole position sensor to detect the magnetic pole position of the rotor.

  For braking, stopping, and positioning of the outdoor fan, the direction and the number of rotations are detected based on the output of the magnetic pole position sensor, and the current supplied to the stator winding is controlled accordingly. However, in the conventional driving device, since three magnetic pole position sensors are used, it has become a cause of increasing the cost.

Therefore, for the purpose of cost reduction, we propose a technology to start the motor after stopping the rotor at a predetermined position by direct current excitation or winding short-circuiting with a smaller number of magnetic pole position sensors than the number of winding phases. (For example, refer to Patent Document 1).
Japanese Patent Application Laid-Open No. 10-290592

  However, when the external force acting on the motor is strong, the rotor cannot be stopped because the brake torque is weak when the winding is short-circuited.

  Moreover, since direct current excitation may or may not work depending on the position of the rotor, if the direct current excitation is weak, the rotor cannot be stopped and is shaken off.

  Although it is conceivable to increase the DC excitation in order to reliably stop the rotor, to increase the DC excitation, it is necessary to increase the amount of current flowing through the motor winding. If the amount of current flowing through the winding is increased, a strong magnetic field opposite to the direction of the magnetic field generated by the permanent magnet constituting the rotor may be generated in the winding, and the permanent magnet may be demagnetized. .

  An object of the present invention is to provide a control device for a DC brushless motor capable of reliably stopping a rotor at a predetermined position when the motor is rotated by an external force before starting.

In the present invention, a DC brushless motor, one magnetic pole position sensor for detecting the magnetic pole position of the rotor of the DC brushless motor, and a plurality of switching elements are connected in a three-phase bridge, and a DC voltage is changed to an AC voltage by opening and closing the switching elements. An inverter circuit for converting and supplying to the DC brushless motor, and a control means for opening and closing the switching element based on an output signal of the magnetic pole position sensor, the control means before the start of the DC brushless motor In synchronization with the output signal of the magnetic pole position sensor, one of the positive voltage side and negative voltage side switching elements is energized with PWM and one of the other switching elements is turned on to brake the rotor. This is a control device for a DC brushless motor.

  As a result, even when the fan is rotating due to an external factor, the DC excitation of the two patterns by PWM energization is switched at a predetermined magnetic pole position, so that the driving circuit and the motor are not overloaded. The brushless motor can be reliably braked and stopped.

  The DC brushless motor control device according to the present invention can be reliably and quickly performed even when the motor rotates due to an external factor, regardless of the rotation direction, without imposing an excessive burden on the drive circuit and the motor. The DC brushless motor can be braked and stopped.

  In the first invention, a DC brushless motor, one magnetic pole position sensor for detecting the magnetic pole position of the rotor of the DC brushless motor, and a plurality of switching elements are connected in a three-phase bridge, and a DC voltage is exchanged by opening and closing the switching elements. An inverter circuit that converts the voltage into a DC brushless motor and supplies control means for opening and closing the switching element based on the output signal of the magnetic pole position sensor, the control means before starting the DC brushless motor In synchronization with the output signal of the magnetic pole position sensor, one of the positive voltage side and negative voltage side switching elements is PWM-energized and the other switching element is turned on to brake the rotor. Even if the motor is rotating due to external factors, the drive circuit and the motor Braking without placing an excessive burden, it is possible to enable the stop.

  In a second aspect of the invention, the control means forms and outputs two patterns of DC excitation signals to brake the rotation of the rotor of the DC brushless motor, so that the motor rotates due to an external factor. In particular, even when the external force is strong, the vehicle can be reliably braked and stopped.

  According to a third aspect of the invention, in particular, the DC excitation signals of the two patterns of the second aspect of the invention are selected and output according to the signal level of the output signal of the magnetic pole position sensor. When the motor rotates due to an external factor, the motor can be reliably braked and stopped regardless of the rotation direction.

  According to the fourth aspect of the invention, the DC excitation signal of the two patterns of the second aspect of the invention is switched with a predetermined electrical angle θ delayed from the edge of the output signal of the magnetic pole position sensor. When rotating, it is possible to suppress the generation of unnecessary acceleration torque as much as possible, and to reliably brake and stop.

  According to a fifth aspect of the invention, in particular, the magnetic pole position sensor according to the first aspect of the invention is provided at a position that is decentered by an electrical angle of 30 ° in the normal rotational direction from the center of any one phase of the stator winding, so A large braking torque can be obtained when the vehicle is rotating due to factors, and braking and stopping can be performed reliably.

  In the sixth aspect of the invention, particularly when the predetermined electric angle θ is set to 90 °, when the motor rotates due to an external factor, generation of unnecessary acceleration torque is suppressed as much as possible, thereby reliably braking and stopping. Can be made.

  According to the seventh aspect of the invention, in particular, the time corresponding to the predetermined electrical angle θ of the sixth aspect of the invention is calculated from the previous cycle of the electrical angle of 180 °, whereby the motor is rotated due to an external factor. In this case, the microcomputer in the control means 10 can be braked and stopped with a relatively small load.

  In the eighth aspect of the invention, in particular, by obtaining the time corresponding to the predetermined electrical angle θ of the sixth aspect of the invention from the previous electrical angle 180 ° period and the previous electrical angle 180 ° period, Even when the vehicle is decelerated by braking, the generation of acceleration torque can be suppressed as much as possible, and braking and stopping can be performed in a short time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
Hereinafter, a first embodiment in which the present invention is applied to a DC brushless motor that drives a fan provided in an outdoor unit of an air conditioner, for example, will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a control device for DC brushless motor 1 according to Embodiment 1 of the present invention. In FIG. 1, a DC brushless motor 1 is used as a motor for driving an outdoor fan provided in an outdoor unit of an air conditioner. The U-phase, V-phase, and W-phase stator windings of the DC brushless motor 1 are neutral. A star connection is made at point N, and a magnetic pole position sensor 2 is provided on the stator. Among these, the U, V, and W phase windings of the stator are connected to the inverter circuit 3, and the connection points are U, V, and W, respectively. Further, the output signal line from the magnetic pole position sensor 2 is connected to the control means 5.

In the inverter circuit 3, Q _u , Q _v , Q _w , Q _x , Q _y , and Q _z are three-phase bridge connected.

That is, a series connection circuit of switching elements Q _u and Q _x, a series connection circuit of switching elements Q _v and Q _{y, and} a series connection circuit of switching elements Q _w and Q _z are connected in parallel, and one end thereof is a DC power source. The other end is connected to the negative electrode of the DC power source 4.

These switching elements Q _u , Q _v , Q _w , Q _x , Q _y , Q _z are connected in parallel with diodes D _u , D _v , D _w , D _x , D _y , D _{z for recirculation} respectively. Has been.

Further, in order to drive the switching elements Q _u , Q _v , Q _w , Q _x , Q _y , Q _z , the control means 5 drives S _u , S _v , S _w , S _x , S _y , S _z . A signal is output to the driving means 6.

  The operation of the first embodiment configured as described above will be described below.

Here, the switching elements Q _u , Q _v , and Q _w are referred to as switching elements on the positive voltage side of the inverter circuit 3, and the switching elements Q _x , Q _y , and Q _z are referred to as switching elements on the negative voltage side of the inverter circuit 3. I will do it.

  The magnetic pole position sensor 2 outputs a high level signal when detecting the N magnetic pole of the rotor, and outputs a low level signal when detecting the S magnetic pole of the rotor.

  2 to 13 show the internal structure of the DC brushless motor 1 when the rotor has two poles and the stator has three slots.

  In FIG. 2, in order to simplify the description, the magnetic pole positions are equally divided into twelve, and numbers 0 to 11 are assigned to define the magnetic pole position numbers and the positional relationship between the rotor and the stator.

  When the position of FIG. 2, that is, the magnetic pole position where the output signal of the magnetic pole position sensor 2 falls from the high level to the low level is 0, and the rotation is in the normal rotation direction (the direction of the arrow shown), FIGS. As shown, the magnetic pole position shifts from 0 to 11 in ascending order.

  On the other hand, before the air conditioner is started, the outdoor fan that has been rotated by an external force such as wind needs to be temporarily stopped and positioned. Therefore, it is necessary to perform stop control that causes the brushless motor 1 to perform braking, stop, and positioning operations.

Therefore, as a method for braking and stopping the brushless motor 1, the control means 5 sends the drive signals S _u , S _v , S _w , S _x , S _y , S _z to the switching element Q _u via the drive means 6, respectively. , Q _v , Q _w , Q _x , Q _y , Q _z , one of the switching elements on either the positive voltage side or the negative voltage side is PWM-energized and one of the other switching elements is There is a method of stopping the rotor by causing a PWM current to flow through the stator winding in an on state, generating a magnetic field in a predetermined direction.

As a first pattern, the transistor Q _w positive voltage side to the ON state of the DC power supply 4, consider a case where the transistors Q _y of the negative voltage side of the DC power source 4 to the ON state. In this DC excitation pattern, a current path flows from the W point in FIG. 1 to the W phase winding, the neutral point N, the V phase winding, and the V point in FIG. A magnetic field is generated in the direction from the position 0 to the magnetic pole position 6.

  Due to the generated magnetic field, the rotor generates torque toward the magnetic pole position 3 shown in FIG. The DC excitation pattern for generating the torque is referred to as WY DC excitation in this specification.

Further, in order to generate a 180 ° reverse torque with the above-described W-Y DC excitation, the transistor Q _v on the positive voltage side of the DC power supply 4 is turned on and the transistor Q _z on the negative voltage side of the DC power supply 4 is turned on. Consider the case where it is turned on. In this DC excitation pattern, a current path flows from the V point in FIG. 1 to the V phase winding, the neutral point N, the W phase winding, and the W point in FIG. A magnetic field is generated in the direction from the position 6 to the magnetic pole position 0.

  Due to the generated magnetic field, the rotor is rotated by 180 ° in electrical angle with WY DC excitation, and torque is generated in the direction of the magnetic pole position 9 shown in FIG. This pattern of DC excitation is referred to herein as VZ DC excitation.

  A description will be given of the rotor braking control necessary for starting when the rotor is rotated by an external force with reference to FIGS.

  In order to apply a braking torque to the rotor, it is necessary to apply DC excitation according to the magnetic pole position of the rotor.

  For example, when the magnetic pole position is in FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG. A braking torque can be generated.

However, if W-Y DC excitation is applied when the magnetic pole positions are in FIGS. 11, 12, 13, 13, 2, 3, 4, 4, and 5, acceleration torque is generated in the rotor. It will be.

  On the other hand, in VZ DC excitation, torque is generated in the reverse direction (180 °) with respect to WY DC excitation, so that the magnetic pole positions are as shown in FIGS. 11, 12, 13, 2, 3, and 4. 4 and 5, braking torque can be generated in the rotor. However, when the magnetic pole position is in FIGS. 5, 6, 7, 8, 9, 10, and 11, acceleration torque is applied to the rotor. Will be generated.

  Therefore, by switching and outputting two patterns of DC excitation of WY DC excitation and VZ DC excitation, braking torque can be continuously applied during one rotation of the rotor, even when the external force is strong. The rotor can be reliably braked.

  Hereinafter, a control method for switching between two patterns of DC excitation will be described.

  As described above, the DC excitation of the two patterns needs to be switched according to the magnetic pole position of the rotor. In the first embodiment, the magnetic pole position sensor 2 is provided at a position that is eccentric by 30 ° from the center of the V-phase winding in the normal rotation direction of the rotor, as shown in FIGS.

  FIG. 14 shows a time chart of the rotor magnetic pole position, the output signal of the magnetic pole position sensor 2, and the DC excitation pattern output.

  First, when the output of the magnetic pole position sensor 2 is rotating in the normal rotation direction (hereinafter referred to as forward rotation), a falling low level is output at the magnetic pole position 0, and a rising high level is output at the magnetic pole position 6. Is output. A method for applying a DC excitation pattern for braking the rotor during forward rotation will be described below.

  First, output of WY DC excitation is started at a position (magnetic pole position 3) rotated by an electrical angle of 90 ° from a position where the magnetic pole position sensor 2 falls (magnetic pole position 0).

  Next, the WY DC excitation is stopped and switched to VZ DC excitation at a position (magnetic pole position 9) rotated by an electrical angle of 90 ° from a position where the rotor rotates and the output of the magnetic pole position sensor 2 rises (magnetic pole position 6). .

  Further, the VZ DC energization is stopped at the position (magnetic pole position 3) rotated by an electrical angle of 90 ° from the position where the rotor rotates and the output of the magnetic pole position sensor 2 falls (magnetic pole position 0). Switch. The rotor is braked by repeating this control.

  On the other hand, with reference to FIG. 15, a description will be given of the braking control in the case of rotating in the direction opposite to the normal rotation direction by an external force (hereinafter referred to as reverse rotation).

  FIG. 15 shows a time chart of the rotor magnetic pole position, the output signal of the magnetic pole position sensor 2, and the DC excitation pattern output, as in FIG.

  During reverse rotation, the magnetic pole position shifts from 11 to 0 in descending order, and the output of the magnetic pole position sensor 2 rises at the magnetic pole position 0 and falls at the magnetic pole position 6. A method for applying a DC excitation pattern for braking the rotor during reverse rotation will be described below.

  First, output of WY DC excitation is started at a position (magnetic pole position 3) rotated by an electrical angle of 90 ° from a position where the magnetic pole position sensor 2 falls (magnetic pole position 6).

  Next, the WY DC excitation is stopped at a position (magnetic pole position 9) rotated by an electrical angle of 90 ° from the position where the rotor rotates and the output of the magnetic pole position sensor 2 rises (magnetic pole position 0). Switch.

  Further, the VZ DC energization is stopped at the position (magnetic pole position 3) rotated by an electrical angle of 90 ° from the position where the rotor rotates and the output of the magnetic pole position sensor 2 falls (magnetic pole position 6). Switch. The rotor is braked by repeating this control.

  As described above, according to the output level of the output signal of the magnetic pole position sensor 2 of the rotor, the excitation torque can be applied to the rotor regardless of the rotation direction by selecting and exciting one of the two patterns of DC excitation signals. The braking torque can be reliably applied to the rotor without generating it.

  When the rotor is braked by the DC excitation of these two patterns, the cycle of the output signal of the magnetic pole position sensor 2 becomes long, and when the output level is fixed at the high level or the low level, the DC excitation of the two patterns is performed. The position of the rotor can be fixed, that is, stopped by continuing DC excitation by any pattern.

  Further, by delaying the switching timing of the two patterns of DC excitation from the falling edge or rising edge of the magnetic pole position sensor 2 by an electrical angle of 90 °, the rotor can be reliably braked without generating acceleration torque. .

  14 and 15, a dead time is provided to prevent the upper and lower arms from being short-circuited when switching between the two patterns of DC excitation.

  In the first embodiment, the DC excitation pattern is switched by delaying the electrical angle by 90 ° from the edge of the output signal of the magnetic pole position sensor 2, but in actual control, it is necessary to obtain a delay time corresponding to the electrical angle of 90 °. . A method for obtaining the delay time will be described with reference to FIG.

  FIG. 16 shows an output signal of the magnetic pole position sensor 2 when the rotor is brake controlled. The output signal of the magnetic pole position sensor 2 is input to the control means 5, and an internal microcomputer (not shown) measures the period of 180 ° electrical angle from edge to edge at any time using a timer function.

In FIG. 16, t ₀ , t ₁ , t ₂ , and t ₃ represent the time when the edge of the output signal of the magnetic pole position sensor 2 is switched, and T ₀ , T ₁ , T ₂ , and T ₃ are from the edge to the edge. This represents a cycle of an electrical angle of 180 °.

Here, for example, at time t ₂ , T ₂ (90 °), which is a period of 90 ° electrical angle in period T ₂ , is obtained by calculating the following equation.

_{T 2 (90 °) = T} 1/2
Furthermore, similarly for T ₃ (90 °)
_{T 3 (90 °) = T} 2/2
Thus, by obtaining the delay time corresponding to the current electrical angle of 90 ° from the previous 180 ° cycle, the braking of the rotor can be realized with a relatively small burden on the microcomputer inside the control means 5.

In order to simplify the description in the first embodiment, the rotor has two poles and the stator has three slots as shown in FIGS. 2 to 13, but the rotor has two poles and the number of stator slots. In the case of a motor having 3n, the description so far is the same (n is a natural number).

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. 1 to 16 are the same as those in the first embodiment, and a description thereof will be omitted.

  As described in the first embodiment, the two patterns of DC excitation are switched and delayed by an electrical angle of 90 ° from the edge of the magnetic pole position sensor 2.

  FIG. 17 shows an output signal of the magnetic pole position sensor 2 when the rotor is brake-controlled.

In FIG. 17, t ₀ , t ₁ , t ₂ , and t ₃ represent the time at which the edge of the output signal of the magnetic pole position sensor 2 is switched, and T ₀ , T ₁ , T ₂ , and T ₃ are from the edge to the edge. This represents a cycle of an electrical angle of 180 °.

  On the other hand, during the braking control, the output signal of the magnetic pole position sensor 2 has a cycle of an electrical angle of 180 ° from edge to edge as the rotational speed decreases as shown in the figure.

Therefore, when the delay time corresponding to the current electrical angle of 90 ° is obtained from the previous 180 ° period as in the first embodiment, the electrical angle is delayed by 90 ° because T ₁ <T _2. The acceleration torque works on the rotor.

Therefore, for example, time t ₂ T ₂ is an electrical angle of 90 ° period in the periodic T ₂ at (90 °) is and 180 ° period T ₀ before the previous, with the previous 180 ° period T _1, as shown in the following equation Ask.

T ₂ (90 °) = T ₁ ² / T _0/2
Furthermore, similarly for T ₃ (90 °)
_{T 3 (90 °) = T} 2 2 / T 1/2
As a result, even when the rotational speed of the rotor is decelerated by braking, it is possible to switch the DC excitation pattern while suppressing the acceleration torque as much as possible.

  As described above, the DC brushless motor control means according to the present invention does not place an excessive burden on the drive circuit and the motor when the fan rotates due to an external factor, and further demagnetizes the permanent magnet. Therefore, the present invention can be applied not only to an outdoor fan of an air conditioner but also to a brushless motor that is freely rotating at the time of startup due to an external factor.

The block diagram which showed the structure of the DC brushless motor control means in Embodiment 1 of this invention FIG. 3 shows the internal structure of the DC brushless motor according to Embodiment 1 of the present invention, and shows the magnetic pole position 0 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 1 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 2 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 3 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 4 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 5 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 6 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 7 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 8 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 9 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 10 of the rotor with respect to the magnetic pole position sensor 2. FIG. 3 shows the internal structure of the DC brushless motor according to the first embodiment of the present invention, and shows the magnetic pole position 11 of the rotor with respect to the magnetic pole position sensor 2. Time chart of DC excitation pattern during forward rotation in Embodiment 1 of the present invention Time chart of DC excitation pattern during reverse rotation in Embodiment 1 of the present invention The figure of the output signal of magnetic pole position sensor 2 when carrying out braking control of the rotor in Embodiment 1 of the present invention The figure of the output signal of magnetic pole position sensor 2 when carrying out braking control of the rotor in Embodiment 2 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC brushless motor 2 Magnetic pole position sensor 3 Inverter circuit 4 DC power supply 5 Control means 6 Drive means

Claims (8)

A DC brushless motor, a magnetic pole position sensor for detecting a magnetic pole position of the rotor of the DC brushless motor, and a plurality of switching elements are connected in a three-phase bridge, and the DC voltage is converted into an AC voltage by opening and closing the switching elements; An inverter circuit to be supplied to the DC brushless motor; and a control unit that opens and closes the switching element based on an output signal of the magnetic pole position sensor. The control unit includes the magnetic pole position sensor before starting the DC brushless motor. One of the switching elements on either the positive voltage side or the negative voltage side is PWM-energized in synchronization with the output signal, and one of the other switching elements is turned on to brake the rotor. DC brushless motor drive device. 2. The DC brushless motor driving apparatus according to claim 1, wherein the control means forms and outputs two patterns of DC excitation signals in order to brake the rotation of the rotor of the DC brushless motor. 3. The DC brushless according to claim 1, wherein two patterns of DC excitation signals are output by selecting one of the two patterns according to a signal level of an output signal of the magnetic pole position sensor. Motor drive device. The DC brushless motor drive according to any one of claims 1 to 3, wherein two patterns of DC excitation signals are switched with a predetermined electrical angle θ delayed from an edge of an output signal of the magnetic pole position sensor. apparatus. 5. The DC brushless motor according to claim 1, wherein the magnetic pole position sensor is provided at a position deviated by an electrical angle of 30 ° in a normal rotation direction from the center of any one phase of the stator winding. Drive device. 6. The DC brushless motor driving apparatus according to claim 5, wherein the predetermined electrical angle [theta] is 90 [deg.]. The DC brushless motor driving device according to any one of claims 1 to 6, wherein a time corresponding to a predetermined electrical angle θ is obtained by calculation from a cycle of a previous electrical angle of 180 °. The DC brushless according to any one of claims 1 to 6, wherein a time corresponding to a predetermined electrical angle θ is obtained by calculation from a previous electrical angle 180 ° cycle and a previous electrical angle 180 ° cycle. Motor drive device.

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