JP2012065412A - Motor driving device, and electrical equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless DC motor driving device that can be easily expanded to various models, requiring no position sensor and no adjustment by motor constants and speeds of a brushless DC motor.SOLUTION: Two phases of a three phase brushless DC motor 4 is connected to the output of an inverter 3 formed by a two phase bridge, and the connection line of serially connected smoothing capacitors 2e and 2f in a smoothing rectifier circuit 2 forming a voltage doubler rectifier is connected to the remaining one phase. The brushless DC motor 4 is driven by a rectangular wave by position detection of a position detecting part 5 based on an induction voltage, and a phase of the phase whose position cannot be detected is estimated by a position estimating part 6 based on the position detection timing of two detectable phases to perform commutation.

Description

  The present invention relates to a motor driving device that drives a brushless DC motor and an electric device using the same.

  For example, as disclosed in Patent Document 1, a conventional motor driving device includes a sensor added to a brushless DC motor or a position detection circuit provided with a first-order lag circuit optimized for a brushless DC motor. The position is detected, and driving is performed while switching the phase to be supplied to the brushless DC motor every 120 ° based on the detected position information. FIG. 5 shows a conventional motor driving device described in Patent Document 1. In FIG.

  In FIG. 5, the inverter is composed of a DC power source 201, electrolytic capacitors 2e and 2f, and an inverter 3 formed of switching elements 3a to 3h, and a control circuit 202. The control circuit 202 sets each of the switching elements 3a to 3d to 120. The power is supplied to the brushless DC motor 4 from the connection point of the electrolytic capacitors 2e and 2f, the connection point of the switching elements 3a and 3c, and the connection point of the switching elements 3b and 3d. . It also has a position sensor 203 that reverses the output when it matches the 0 ° position of each phase of the motor, and switches the 120 ° energization pattern by performing commutation 30 ° after the signal is switched. However, the brushless DC motor 4 is driven. As another driving method, the energization pattern of the brushless DC motor 4 is not based on the position sensor 203 but based on a signal obtained by passing the first-order lag filter to the induced voltage of the phase of the brushless DC motor connected to the switching elements 3a to 3d. Driving is performed by switching.

  The conventional motor driving device is used for the inverter 3 by feeding one phase of the three-phase brushless DC motor 4 from the connection point of the electrolytic capacitors 2e and 2f in FIG. 5 of the inverter for driving the brushless DC motor. As a result, the number of switching elements used is reduced, and the size and cost can be reduced.

JP 2000-209890 A

  However, the conventional configuration has a problem that the position sensor cannot be used in a high-temperature and sealed space such as a compressor. Further, since the position sensor is expensive, there is a problem that it is not possible to sufficiently reduce the cost for a system that is realized without using a conventional sensor. In addition, when using a first-order lag filter, it is necessary to set an optimum value individually depending on the speed of the motor, etc., which increases the number of man-hours for development and increases the cost when deploying multiple models. Have.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and provides a brushless DC motor drive device that does not require a sensor and can be easily deployed in various models that do not require adjustment by the motor constant or speed of the brushless DC motor. provide.

The motor drive device of the present invention is a motor drive device that drives a brushless DC motor.
Furthermore, the present invention provides a smoothing rectifier circuit that forms a voltage doubler rectifier circuit by four rectifier diodes bridged with an AC power supply as an input and a smoothing capacitor, and four sets of voltages smoothed by the smoothing rectifier circuit as inputs. An inverter that forms a two-phase bridge with a switching element, a brushless DC motor that receives an output from the inverter and an output from a connecting portion of a smoothing capacitor connected in series with the smoothing rectifier circuit; and The phase of the brushless DC motor connected to the position detecting unit for detecting the motor phase from the induced voltage and the connecting part of the smoothing capacitor connected in series to the smoothing rectifier circuit from the detection timing detected by the position detecting unit. A position estimator for estimating the motor phase, and the position detector and the position estimator as inputs. Determining a conduction phase Te and having a drive unit that outputs to the inverter.

  According to such a configuration, the motor position information is acquired by the same control method regardless of the speed of the brushless DC motor, and stable driving is performed.

  The motor driving device of the present invention can obtain stable position driving by acquiring motor position information by the same control method regardless of the motor speed. This eliminates the need for individual adjustments depending on the brushless DC motor or system, and can drive a brushless DC motor that can be easily deployed in various models.

1 is a block diagram of a motor drive device according to Embodiment 1 of the present invention. Timing chart of motor drive device in same embodiment Flowchart showing the operation of the motor drive device in the same embodiment Sectional drawing of the principal part of the brushless DC motor in the same embodiment Block diagram of a conventional motor drive device

  The first invention is a smoothing rectifier circuit comprising a voltage doubler rectifier circuit comprising four rectifier diodes bridged with an AC power supply as an input and a smoothing capacitor, and four sets of voltages smoothed by the smoothing rectifier circuit as inputs. An inverter that forms a two-phase bridge with a switching element, a brushless DC motor that receives an output from the inverter and an output from a connecting portion of a smoothing capacitor connected in series with the smoothing rectifier circuit; and A position detecting unit that detects a motor phase from an induced voltage and a position that estimates a motor phase of a phase connected to a connecting part of a smoothing capacitor connected in series with the smoothing rectifier circuit from a detection timing detected by the position detecting unit. The estimation unit, the position detection unit, and the position estimation unit are input to determine an energized phase and to the inverter Because it has a drive unit that can be operated, it can be driven stably with the same control system regardless of the type and speed of the motor, so it can be easily deployed to various models, It is possible to reduce development man-hours when installing.

  In the second invention, in particular, the position estimation unit according to the first invention calculates the average of the output intervals of the position detection unit, and estimates the position from the average. Since it becomes smaller, it can be realized by a microcomputer or the like that operates with a slower clock, so that power consumption and cost can be reduced.

According to a third aspect of the invention, in particular, the position estimation unit of the first aspect of the invention records a position detection timing that appears in each section obtained by dividing the rotation of the brushless DC motor into the product of the number of poles and the number of phases. By having an estimated position detection timing in the middle of the position detection timing of the previous and subsequent sections recorded by the timing recording section in the section where the position detection does not occur with the recording section, It becomes stronger and can drive devices with speed pulsation more stably.

  In the fourth aspect of the invention, in particular, the timing recording unit of the third aspect of the invention can average and record the position detection timing of each section, so that disturbance can be mitigated and more stable against noise and the like. Driving can be performed.

  In the fifth aspect of the invention, in particular, a compressor is used as the driving load of the brushless DC motor of the first to fourth aspects of the invention. In the drive control of the compressor, high-precision rotation speed control, acceleration control, and the like are not required unlike industrial servomotor control. Further, the compressor has a load with a relatively large inertia, and it can be said that the fluctuation of the speed in a short time is a very small load. Therefore, it is possible to easily estimate the position detection timing of the remaining one phase from the position detection interval for two phases.

  In the sixth invention, in particular, the compressor of the fifth invention is a reciprocating compressor. As a result, the reciprocating type that performs reciprocating motion is structurally connected to the rotor, which is metallic and heavy, with a heavy crankshaft and piston. Since it becomes extremely small, more stable driving is possible.

  The seventh aspect of the invention is particularly an electric device using the motor driving device of any one of the first to sixth aspects of the invention. Thereby, when it uses for a refrigerator as an electric equipment, since load fluctuation | variation is not sudden, the more stable drive is attained. In addition, even if there are various capacities such as a refrigerator and the load conditions are different, there is no need to individually adjust the load conditions.

(Embodiment 1)
FIG. 1 is a block diagram of a motor drive device according to Embodiment 1 of the present invention. In FIG. 1, an AC power source 1 is a general commercial power source, and in Japan, a power source of 50 or 60 Hz with an effective value of 100V. The motor driving device 22 is connected to the AC power source 1 and drives the brushless DC motor 4. Hereinafter, the motor drive device 22 will be described.

  The smoothing rectifier circuit 2 rectifies and smoothes AC power into DC power with the AC power supply 1 as an input. The voltage doubler rectifier circuit is composed of four bridge-connected rectifier diodes 2a to 2d and smoothing capacitors 2e and 2f. It is comprised by.

  The inverter 3 converts the DC power from the smoothing rectifier circuit 2 into AC power. The inverter 3 is configured by connecting four switching elements 3a to 3d in a two-phase bridge. The four return current diodes 3e to 3h are connected to the switching elements 3a to 3d in the reverse direction.

  The brushless DC motor 4 includes a rotor 4a having a permanent magnet and a stator 4b having a three-phase winding. In the brushless DC motor 4, the alternating current generated by the inverter 3 flows in two phases of the three-phase windings of the stator 4b. The remaining one phase is connected to a connecting line between the negative electrode side of the smoothing capacitor 2e and the positive electrode of the smoothing capacitor 2f, thereby generating a three-phase alternating current and rotating the rotor 4a. In this embodiment, the number of poles of the rotor is four.

  The position detection unit 5 acquires the terminal voltage of the brushless DC motor 4 in the present embodiment. That is, the magnetic pole relative position of the rotor 4a of the brushless DC motor 4 is detected. Also, the midpoint potential is made from the terminal voltage. Specifically, the position detector 5 detects the relative rotational position of the rotor 4a by comparing the midpoint potential with the terminal voltage.

  The position estimation unit 6 has a timing recording unit 7. The timing recording unit 7 divides one rotation of the motor into 12 which is the product of the number of poles 4 and the number of phases 3 of the brushless DC motor 4 and records the position detection timing in each section. When the timing is recorded, a history of position detection timing for 8 times in the same section is stored, and an average of 8 times is calculated as the position detection timing of each section. The position estimation unit 6 calculates the middle of the position detection timings of the preceding and succeeding sections in the section where the position detection timing is not recorded, and estimates the calculation result as the position detection timing and outputs it to the waveform generation unit 8. In which section the timing recording unit 7 records the timing is sequentially changed at the timing when the energization pattern of the waveform generation unit 8 changes.

  The timing recording unit 7 is initialized so that the waveform generation unit 8 stores the past 8 times while forcing the brushless DC motor to switch the energization pattern regardless of the position detection timing. This is done by determining the presence or absence and recording the timing.

  The speed detection unit 9 averages the position detection timings detected by the position detection unit 5 and multiplies the product by the product of the number of poles and the number of phases (12 in this embodiment) to determine the cycle of one rotation of the brushless DC motor. Calculate the speed. This calculation result is output to the waveform generator 8.

  The waveform generator 8 generates a waveform signal for driving the switching elements 3 a to 3 d of the inverter 3. The waveform signal is a rectangular wave signal having an energization angle of 120 degrees to 150 degrees. In order to smoothly drive the brushless DC motor 4 having the three-phase winding, the energization angle needs to be 120 degrees or more. On the other hand, in order for the position detection unit 5 to detect the position based on the induced voltage, an interval of 30 degrees or more is necessary as the ON / OFF interval of the switching element. For this reason, the upper limit of the conduction angle is 150 degrees obtained by subtracting 30 degrees from 180 degrees. In addition, even if a waveform signal is other than a rectangular wave, the waveform according to a rectangular wave is mentioned. For example, it is a trapezoidal wave having a slope at the rise / fall of the waveform.

  The waveform generation unit 8 generates a waveform signal based on the position information of the position detection unit 5 and the position estimation unit 6. Further, the waveform generator 8 performs pulse width modulation (PWM) duty control in order to keep the rotation speed constant based on the speed detected by the speed detector 9. As a result, the brushless DC motor 4 is efficiently driven with an optimum duty based on the rotational position. The determined output waveform signal is output to the drive unit 10.

  Based on the waveform signal output from the waveform generator 8, the drive unit 10 outputs a drive signal that instructs the supply timing of the power that the inverter 3 supplies to the three-phase winding of the brushless DC motor 4. Specifically, the drive signal turns on or off the switching elements 3a to 3d of the inverter 3 (hereinafter referred to as on / off). As a result, optimum AC power is applied to the stator 4b, the rotor 4a rotates, and the brushless DC motor 4 is driven.

  Next, an electric device using the motor driving device 22 in the present embodiment will be described. A refrigerator 21 will be described as an example of the electric device.

  Although the compressor 21 is mounted on the refrigerator 21, the rotational motion of the rotor 4a of the brushless DC motor 4 is converted into reciprocating motion by a crankshaft (not shown). A piston (not shown) connected to the crankshaft reciprocates in a cylinder (not shown) to compress the refrigerant in the cylinder. That is, the compressor 17 is configured by the brushless DC motor 4 and the crankshaft, piston, and cylinder.

As a compression method (mechanism method) of the compressor 17, an arbitrary method such as a rotary type or a scroll type is used. In this embodiment, the case of the reciprocating type will be described. The reciprocating compressor 17 has a large inertia. Therefore, the brushless DC motor 4 of the compressor 17
Are driven synchronously, the drive of the compressor 17 is stabilized.

  The refrigerant compressed by the compressor 17 constitutes a refrigeration cycle in which the refrigerant passes through the condenser 18, the decompressor 19, and the evaporator 20 in this order and returns to the compressor 17 again. At this time, since the condenser 18 radiates heat and the evaporator 20 absorbs heat, cooling and heating can be performed. A refrigerator 21 is configured with this refrigeration cycle. When a motor drive device is incorporated in the refrigerator 21, a space is required, but the motor drive device of the present invention can be miniaturized and can improve the internal volume ratio. In addition, there are refrigerators with various capacities, but it is not necessary to optimize the drive system (first-order lag filter or the like) for each, and the development efficiency can be improved. As another example of the electric device, there is an air conditioner including a condenser or an evaporator provided with a blower.

  The operation of the motor drive device 22 configured as described above will be described.

  First, the operation of the brushless DC motor 4 driven by a signal output from the waveform generator 8 will be described. FIG. 2 is a timing chart of the motor driving device 22 in the present embodiment. The signal for driving the inverter 3 is a drive signal output from the drive unit 10 in order to turn on / off the switching elements 3 a to 3 d of the inverter 3. In this case, the drive signal is obtained based on the waveform signal. The waveform signal is output from the waveform generator 8 based on the output of the position detector 5.

  In FIG. 2, signals V, W, Y, and Z are drive signals for turning on / off the switching elements 3a, 3c, 3b, and 3d, respectively. Waveforms Iu, Iv, and Iw are respectively U-phase, V-phase, and W-phase current waveforms of the winding of the stator 4b. Waveforms Vu, Vv, and Vw are U-phase, V-phase, and W-phase terminal voltage waveforms, and Vp of the vertical axis memory is an output voltage value obtained by connecting smoothing capacitors 2e and 2f in series. A waveform Vm is a waveform of the midpoint potential of the terminal voltages of the U phase, the V phase, and the W phase. The timing Pd represents the position detection timing by the position detection unit 5, and the timing Pg is the position detection timing estimated by the position estimation unit 6.

  In the section where the signals V, W, Y, and Z are not turned on simultaneously, the induced voltage of the phase that is not turned on appears in the terminal voltage, so that the position can be detected by the position detector 5. Specifically, in the section A in which only Z is ON, the position of the V phase can be detected, and the position detection unit 5 determines the timing a at which the voltage values coincide with each other by comparing the voltages Vm and Vv. To output. The same applies to the section C in which only the signal V is ON, and it is possible to detect the position of the W phase, which is the phase in which the signal is not ON, and determine the timing c at which the voltages Vm and Vw match as the position detection timing. To output. After a time corresponding to 30 ° from these position detection timings, the waveform generator 8 changes the energization pattern and outputs it. The conversion between the angle and the time can be easily calculated by input from the speed detection unit 9. The drive unit 10 switches on / off of the switching elements 3a to 3d of the inverter based on the information on the waveform energization pattern. Since the reluctance torque can be used in the salient pole motor by performing commutation between 0 ° and less than 30 ° instead of 30 ° from the position detection timing, a larger torque can be obtained.

  On the other hand, in the interval in which two signals are simultaneously turned on, no induced voltage appears in the terminal voltages of all three phases, and position detection cannot be performed. Specifically, in the section B in which the signals V and Z are on, the terminal voltage Vu is always fixed at half of the voltage value Vp, so that the voltage Vm always matches the terminal voltage Vu. The signal cannot be obtained.

  At this time, the waveform generation unit 8 acquires the position detection timing b estimated by the position estimation unit 6 as position information, treats this information in the same manner as the information of the position detection unit 5, and changes the energization pattern, so that the brushless DC The motor 4 can be driven.

  Next, operation | movement of the position estimation part 6 is demonstrated using the flowchart of FIG. In FIG. 3, the position detection interval timer is always operating.

  First, in step 101, it is determined whether only one phase of the signal output from the waveform generator 8 is on. If there is only one phase (Yes in step 101), the position can be detected and the process proceeds to step 102.

  In step 102, since it is a section in which position detection is possible, it is determined whether position detection has been performed. If position detection is not performed (No in step 102), step 102 is repeated again. If position detection has been performed (Yes in step 102), the position detection timing is acquired and the process proceeds to step 103.

  In Step 103, the timing recording unit 7 calculates an average from the total of eight position detection timings of the past seven times of the current position detection timing and the timing of the position detection interval in the current energization pattern section, and stores the result. . Next, the routine proceeds to step 104.

  In step 104, the oldest detection timing of the past seven times is replaced with the current detection timing, so that the past seven detection timings are always stored. By storing the average of the past 8 times, it becomes more resistant to noise. However, in the case of a system that is not easily affected by noise, it is possible to reduce the computation load by directly storing the timing detected this time, and step 104 is omitted. Can do. Next, the process proceeds to step 105.

  In step 105, it is determined whether the signal W or Z in which the next energization pattern is two-phase on is on. If the signal W or Z is on (Yes in step 105), the process proceeds to step 106, and the estimated position detection timing is set. If the ON signal is V or Y (No in step 105), it is not necessary to set the detection timing of the estimated position, and the process proceeds to step 107.

  In step 106, the position detection interval of the second ahead section is acquired, and half of the interval is output from the position estimation unit 6 as the estimated position detection timing. The second section is a section in which only Y is turned on if the currently turned-on signal is W, and is a section in which V is turned on when the signal Z is turned on. Next, the process proceeds to step 107, and after the timer measuring the position detection interval is cleared in step 107, the process is restarted and the flow is exited.

  On the other hand, if the two phases are ON in step 101 (No in step 101), the process proceeds to step 108.

  In step 108, it is determined whether the time corresponding to the estimated position detection timing set in step 106 has elapsed from the previous position detection timing. If the time has not elapsed (No in Step 108), the process proceeds again to Step 108, and if the time has elapsed (Yes in Step 108), the process proceeds to Step 109. The previous position detection is position detection in a section where only Z is on when the signals V and Z are on, and only W is on when the signals W and Y are on. The position of the section is detected.

  Since it is the timing of the estimated position detection in step 109, the position estimation unit 6 outputs a signal similar to the position detection. And it goes out of this flow.

The position estimation unit 6 can output the signal Pd shown in FIG. 2 by calling the above steps every time the pattern of the signal output from the waveform generation unit 8 is changed. What is the motor speed, motor constant, etc. Regardless, the brushless DC motor 4 can be driven.

  As described above, the present invention includes a smoothing rectifier circuit 2 that constitutes a voltage doubler rectifier circuit by four rectifier diodes 2a to 2d bridge-connected with an AC power supply 1 as an input, and smoothing capacitors 2e and 2f, Inverter 3 constituted by a two-phase bridge by return current diodes 3e-3h connected to four sets of switching elements 3a-3d in the reverse direction with the voltage smoothed by the smoothing rectifier circuit, and the output of inverter 3 The motor phase of the brushless DC motor 4 that receives the output from the connecting portion of the smoothing capacitor connected in series of the smoothing rectifier circuit 2 and the phase of the brushless DC motor connected to the inverter 3 from the induced voltage of the brushless DC motor 4. Is connected in series to the position detection unit 5 for detecting the signal and the smoothing rectifier circuit 2 from the detection timing detected by the position detection unit 5. The position estimation unit 6 for estimating the motor phase of the brushless DC motor 4 connected to the connection portions of the smoothing capacitors 2e and 2f, the current detection phase is determined by using the position detection unit 5 and the position estimation unit 6 as inputs, and the inverter 3 The drive unit 10 that outputs to the motor enables stable driving with the same control system regardless of the type and speed of the motor, so it can be easily deployed to various models. This makes it possible to reduce the development man-hours when installed on the PC.

  Further, according to the present invention, the position estimation unit 6 includes a timing recording unit 7 that records the position detection timing that appears in each section obtained by dividing one rotation of the brushless DC motor 4 into the product of the number of poles and the number of phases. In the section where position detection does not occur, the estimated position detection timing is set to the middle of the position detection timings of the preceding and following sections recorded by the timing recording unit 7, so that it is strong against periodic fluctuations in speed. Devices with pulsation and the like can be driven more stably.

  Further, according to the present invention, since the timing recording unit 7 averages and records the position detection timing of each section, it is possible to alleviate the disturbance and to perform stronger and stable driving against noise and the like. .

  Further, since the average of the position detection intervals is calculated, and the result is divided by 1.5, it corresponds to 60 ° for one electrical angle cycle of the brushless DC motor, so the position detection timing before the section where position detection is not possible It is possible to drive more simply by setting the timing at which the elapsed time from the time coincides with the time corresponding to 60 ° as the position detection timing estimated by the position estimation unit 6. As described above, the phase estimation unit 11 calculates the average of the output intervals of the position detection unit 5 and estimates the position from the average, so that the calculation method is simple and the calculation load is reduced. It can be realized with a microcomputer that operates, and power consumption and costs can be reduced.

  In the present invention, the compressor 17 is used as a driving load of the brushless DC motor 4. The drive control of the compressor 17 does not require high-precision rotation speed control, acceleration control, or the like, unlike industrial servo motor control. Further, the compressor 17 is a load having a relatively large inertia, and it can be said that the fluctuation of the speed in a short time is a very small load. Therefore, it is possible to easily estimate the position detection timing of the remaining one phase from the position detection interval for two phases.

  The compressor 17 is a reciprocating compressor. As a result, the reciprocating type that performs reciprocating motion is structurally connected to the rotor, which is metallic and heavy, with a heavy crankshaft and piston. Since it becomes extremely small, more stable driving is possible.

In addition, the present invention is an electric device using a motor driving device. When used in a refrigerator as an electric device, the load fluctuation is not steep, so a small motor driving device that can be driven stably can be provided, and the volume ratio in the warehouse can be increased. In addition, although there are refrigerators with various capacities, it is not necessary to individually adjust each capacity, so that development efficiency can be improved.

  The motor drive device of the present invention can easily deploy a small motor drive device to a device that drives a brushless DC motor. Thereby, not only a refrigerator and an air conditioner but also a vending machine, a showcase, and a heat pump water heater can be miniaturized and the volume ratio can be increased. In addition, the present invention can be applied to miniaturization of electric devices using brushless DC motors such as washing machines, vacuum cleaners, and pumps.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Smoothing rectifier circuit 3 Inverter 4 Brushless DC motor 4a Rotor 4b Stator 5 Position detection part 6 Position estimation part 7 Timing recording part 8 Waveform generation part 10 Drive part 17 Compressor 21 Refrigerator (electric equipment)
22 Motor drive device

Claims (7)

A smoothing rectifier circuit that constitutes a voltage doubler rectifier circuit by four rectifier diodes and a smoothing capacitor that are bridge-connected with an AC power supply as an input, and a voltage smoothed by the smoothing rectifier circuit as an input, and two phases by four sets of switching elements An inverter constituting a bridge; a brushless DC motor having an output from the inverter and an output from a connecting portion of a smoothing capacitor connected in series to the smoothing rectifier circuit; and a motor phase from an induced voltage of the brushless DC motor A position detecting unit for detecting the motor phase of the phase connected to the connecting part of the smoothing capacitor connected in series of the smoothing rectifier circuit from the detection timing detected by the position detecting unit; The energized phase is determined with the position detector and the position estimator as inputs and output to the inverter Motor driving apparatus and a live part. The motor driving apparatus according to claim 1, wherein the position estimation unit calculates an average of output intervals of the position detection unit and estimates a position from the average. The position estimation unit has a timing recording unit that records a position detection timing that appears in each section obtained by dividing one rotation of the brushless DC motor into the product of the number of poles and the number of phases, and a section in which position detection does not occur The motor drive device according to claim 1, wherein an intermediate position detection timing between the preceding and following sections recorded by the timing recording unit is set as a position detection timing. The motor drive device according to claim 3, wherein the timing recording unit averages and records the timing of position detection in each section. The motor driving device according to any one of claims 1 to 4, wherein the brushless DC motor drives a compressor. The motor driving device according to claim 5, wherein the compressor is a reciprocating compressor. An electric device comprising a brushless DC motor driven by the motor driving device according to any one of claims 1 to 6.

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