JP2006211752A - Precise positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precise positioning device that is saved in energy and equipped with a compact and light driver. <P>SOLUTION: The driver DV1 that drive-controls a linear motor being a brushless DC motor comprises an output current detector 20 that is arranged in the middle of a circuit in which an output current Iu flows to an armature coil 18, and a power semiconductor drive converter 22 that changes a drive form with respect to a power semiconductor on the basis of a detected value of the output current detector. The output current detector outputs a feedback signal Sf to the power semiconductor drive converter on the basis of the detected output current. The power semiconductor drive converter is a device that performs linear drive control, or PWM drive control to the power semiconductor on the basis of a control signal Si. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a precision positioning apparatus using a linear motor as a drive source, and more particularly, to an improvement in a driver that performs drive control of a linear motor.

For example, a positioning table device 2 shown in FIGS. 6 to 8 is known as a precision positioning device used in a semiconductor manufacturing apparatus, a semiconductor inspection apparatus, or the like (for example, Patent Document 1).
As shown in FIG. 6, the positioning table device 2 moves a pair of linear guides LG supported so that the table TB linearly moves in the left-right direction, and a table TB supported by the linear guides LG in the left-right direction. A linear motor LM to be driven, and a driver DV for controlling the driving of the linear motor LM.

The pair of linear guides LG are parallel to each other in the left-right direction and fixed to the base 4 while being fixed on the base 4, and as shown in FIG. And a slider 10 mounted thereon.
As shown in FIG. 8, the linear motor LM is formed in a U-shaped cross section, and is arranged in parallel between the two guide rails 6 and fixed on the base 4. In the longitudinal direction of the inner surfaces facing each other, a plurality of permanent magnets 14 are arranged adjacent to N, S, N, S,... And different poles, and fixed to the lower surface of the table TB and fixed to the stator 12. A plurality of coreless armatures disposed in the mover 16 so that thrust is applied to the mover 16 in cooperation with the mover 16 entering the space and the magnet array MM disposed in the stator 12. The brushless DC motor includes a coil 18.

Then, by outputting an output current from the driver DV to the linear motor LM, the table TB moves in the left-right direction while being guided by the linear guide LG by driving the linear motor LM.
In the linear motor LM having the above configuration, the magnet row MM is arranged on the stator 12 side to reduce the weight of the mover 16, and the mover 16 having the coreless structure armature coil 18 is used for cogging. Occurrence is suppressed.

Here, a power semiconductor is incorporated in the driver DV. For example, as shown in FIG. 9, in a driver DV to which a constant power supply voltage Vbus is connected in order to flow a three-phase current through the windings U, V, W of the armature coil 18 of the star-connected linear motor LM, A plurality of power semiconductors Uu, Ud, Vu, Vd, Wu, Wd having a three-phase bridge connection are provided. As a method for driving and controlling these power semiconductors, linear drive that generates output currents Iu, Iv, and Iw to the armature coil 18 using voltage drops Eu, Ev, and Ew that occur due to linear characteristics of the power semiconductors. There are control and PWM drive control for generating output currents Iu, Iv, Iw to the armature coil 18 by pulse width modulation.
JP 2001-245464 A

However, the method of controlling the power semiconductor by the linear drive has a problem in terms of energy saving due to an increase in power consumption to the power semiconductor, and generates a high thrust for high acceleration / deceleration movement. Requires a large power semiconductor, and the heat sink for heat dissipation of the power semiconductor is also large, which is problematic in terms of the manufacturing cost of the driver DV.
In addition, the method of controlling the power semiconductor by PWM drive that easily generates high thrust by increasing the output current compared to linear drive is the ON / OFF of each power semiconductor Uu, Ud, Vu, Vd, Wu, Wd. Noise caused by the switching operation of OFF switching is generated and flows as a minute current to the armature coil 18 of the linear motor LM, which may adversely affect the accuracy of positioning the table TB.
Therefore, the present invention has been made in view of the above circumstances, and provides a precision positioning device that can achieve energy saving and can achieve high-precision positioning control while including a small and lightweight driver. The purpose is to do.

  In order to solve the above problems, a precision positioning apparatus according to the present invention includes a linear guide for guiding a table on a base so as to be movable in a linear direction, and the table guided by the linear guide in the linear direction. A linear motor to be driven; and a driver having a power semiconductor for controlling the driving of the linear motor. The linear guide is fixed on the base, and is attached to the table and mounted on the guide rail. A slider mounted thereon, the linear motor having a magnet row in which a plurality of permanent magnets having different polarities of adjacent magnetic poles are arranged in parallel and fixed on the base, and fixed to the table, A brushless DC motor comprising a mover having a coreless armature coil to which thrust is applied in cooperation with the magnet array. In the precision positioning device, the driving state determination means for determining the traveling state of the table, and the power semiconductor of the driver is pulsed when the traveling state determination means determines that the table is traveling in the acceleration / deceleration state. And power semiconductor drive changing means for linearly driving the power semiconductor when the travel state judging means judges that the table is running at a constant speed.

The traveling state determination means determines whether the table is traveling in an acceleration / deceleration state or whether the table is traveling at a constant speed according to a change in an output current value output from the driver to the linear motor. It is preferable to judge.
Further, the traveling state determination means determines that the table is traveling in an acceleration / deceleration state when the output current value is equal to or greater than a predetermined reference value, and when the output current value falls below the predetermined reference value, It is preferable to determine that the table is traveling at a constant speed.

  On the other hand, as a precision positioning device of another configuration, a linear guide that guides the table on the base so as to be movable in the linear direction, and a linear motor that causes the table guided by the linear guide to travel in the linear direction; A driver having a power semiconductor for controlling the driving of the linear motor, the linear guide being fixed on the base, and a slider mounted on the guide rail and mounted on the lower surface of the table A stator having a magnet array in which a plurality of permanent magnets having different polarities of adjacent magnetic poles are arranged in parallel and fixed on the base; and the magnet array fixed to the table. Precision position as a brushless DC motor with a mover having a coreless armature coil to which thrust is applied in cooperation with The power semiconductor of the driver is controlled by linear drive, and the required characteristic calculation means for calculating the current required characteristic of the linear motor, and the calculated value of the required characteristic calculation means based on the calculated value There is a precision positioning device provided with power supply voltage changing means for changing the power supply voltage of a driver.

In this apparatus, the power supply voltage changing means includes a transformer for stepping down an AC voltage supplied from the outside, a switching tap connected between the secondary side of the transformer and the driver, and the necessary characteristic calculating means. It is preferable to include tap switching control means for performing switching control of the switching tap by a control signal based on the calculated value.
The power supply voltage changing means may include a power supply voltage semiconductor and drive control means for driving and controlling the power supply voltage semiconductor by a control signal based on a calculated value of the necessary characteristic calculating means.
Furthermore, the drive control means may drive the power supply voltage semiconductor by pulse width modulation.
Furthermore, an air bearing can be used instead of the linear guide constituted by the guide rail and the slider.

  According to the precision positioning device of the present invention, energy saving can be achieved, and high-precision positioning control can be realized while including a small and lightweight driver.

Hereinafter, an embodiment of a positioning table device according to the precision positioning device of the present invention will be described with reference to the drawings.
The same components as those shown in FIGS. 6 to 9 are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 shows a circuit of the driver DV1 of the first embodiment that controls the driving of the linear motor LM according to the present invention. FIG. 1 is an enlarged view of a main part by changing a part of the circuit of FIG.

The driver DV1 of the present embodiment includes an output current detector 20 disposed in the middle of the circuit through which the output current Iu flows through the armature coil 18, and the power semiconductors Uu and Ud based on the detection value of the output current detector 20. And a power semiconductor drive converter 22 for changing the drive format.
The output current detector 20 outputs a feedback signal Sf based on the detected output current Iu to the power semiconductor drive converter 22.

  The power semiconductor drive converter 22 is a device that performs linear drive control or PWM drive control on the power semiconductors Uu and Ud based on the control signal Si. The power semiconductor drive converter 22 compares and calculates the feedback signal Sf output from the output current detector 20 and the reference value Sk, and performs linear drive control or PWM drive control based on the comparison result.

Since the thrust of the linear motor LM, which is a brushless DC motor, is proportional to the output current Iu, the output current Iu also increases when the table TB is traveling in the acceleration / deceleration state. On the other hand, when the table TB is traveling at a constant speed, the output current Iu is small.
Therefore, the power semiconductor drive converter 22 uses the reference value Sk described above as a value corresponding to the output current Iu when the table TB travels in the acceleration / deceleration state, and compares the reference value Sk with the feedback signal Sf. When Sf ≧ Sk, the power semiconductors Uu and Ud are controlled by PWM drive, and when Sf <Sk, the power semiconductors Uu and Ud are controlled by linear drive.

The power semiconductors Uu and Ud that are linearly controlled generate the output current Iu using their own linear characteristics. In addition, the power semiconductors Uu and Ud that are PWM-driven are compared with the control signal Si and the triangular wave signal and modulated to a pulse width to generate an output current Iu.
Here, although not shown, other power semiconductors Vu, Vd, Wu, Wd are similarly provided with output current detectors 20 in the middle of a circuit through which output currents Iv, Iw flow in armature coil 18, respectively. And a power semiconductor drive converter 22 that changes the drive type (linear drive, PWM drive) for the power semiconductors Vu, Vd or Wu, Wd based on the detection values of these output current detectors 20. It shall be.

The power semiconductor drive converter 22 of the present embodiment corresponds to the power semiconductor drive change means of the present application, and the output current detector 20 of the present embodiment corresponds to the running state determination means of the present application.
As described above, in the driver DV1 of the present embodiment, when the table TB has a low thrust that travels at a constant speed, the power semiconductor drive converter 22 operates with respect to the power semiconductors Uu, Ud, Vu, Vd, Wu, and Wd. Since linear drive control is performed, a large power semiconductor is not required. Accordingly, the power consumption during the linear drive control can be reduced, and the heat sink for heat dissipation of the power semiconductor can be reduced in size, so that the positioning table device 2 including the driver DV1 of the present embodiment is In addition to energy saving, the driver DV1 can be reduced in size and weight.

Furthermore, during linear drive control, since switching noise of the power semiconductors Uu, Ud, Vu, Vd, Wu, Wd is not generated and precise driving is possible, if the linear guide LG is replaced with an air bearing, Accurate positioning control can be expected.
Further, when the table TB is traveling in a high acceleration / deceleration state, high-accuracy positioning is not required, and at that time, the power semiconductor drive converter 22 applies to the power semiconductors Uu, Ud, Vu, Vd, Wu, Wd. Therefore, even if the switching noise of the power semiconductors Uu, Ud, Vu, Vd, Wu, Wd is generated, the positioning accuracy of the positioning table device 2 is not affected.

Next, a circuit according to a second embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the driver DV2 is connected to the power supply voltage Vbus via the smoothing capacitor CO, and is connected between the transformer 26 for stepping down the AC voltage, the secondary side of the transformer 26, and the driver DV2. Of the switching tap 28, the required characteristic calculator 30 that calculates the required characteristics of the current linear motor LM that is moving and controlling the table TB, and the switching tap 28 based on the result calculated by the required characteristic calculator 30. And a control signal generator 32 for generating a control signal St for performing switching control. A discharge resistor RO is connected in parallel with the smoothing capacitor CO.

As shown in FIG. 3, the driver DV2 generates an output current Im in the armature coil 18 by controlling the power semiconductor T by linear drive.
The necessary characteristic calculator 30 stores a characteristic map of thrust F-propulsion speed SP of the linear motor LM which is the brushless DC motor shown in FIG. And the speed SPn of the table TB at the current operating point DN calculated from an encoder (not shown) and the current thrust Fn obtained from the output current Im (the thrust of the linear motor LM which is a brushless DC motor is proportional to the output current Iu. 4), one of the required output voltages EM1, EM2, EM3, EM4 is calculated from the characteristic map of FIG. 4 (EM1>EM2>EM3> EM4).

The control signal generator 32 generates the control signal St based on the output voltage calculated by the necessary characteristic calculator 30.
The switching tap 28 switches and controls the secondary side voltage of the transformer 26 in response to the input of the control signal St from the control signal generator 32.
The required characteristic calculator 30 of this embodiment corresponds to the required characteristic calculator of the present invention, and the control signal generator 32 corresponds to the tap switching unit of the present invention.

Next, the operation of this embodiment will be described.
The power supply voltage Vbus of the driver DV2 is set by the output voltage EM and the voltage drop ED of the power semiconductor T as shown in the following equation (1). The output voltage EM is set to a value that overcomes the counter electromotive force generated by the movement of the armature coil 18 of the linear motor LM and allows the output current Im to flow through the coil having impedance.
Vbus = EM + ED
= (P × Im + Eg) + ED
= (P × Im + Ke × v) + ED (1)
P is the impedance, Ke is the counter electromotive force constant, and v is the propulsion speed of the linear motor LM.

  Here, if the power supply voltage Vbus of the driver DV2 is set to a large constant value that can correspond to the maximum thrust and the maximum propulsion speed of the linear motor LM, the capacity of the power semiconductor T must also be increased. The heat sink for heat dissipation of the power semiconductor T is also large. Conversely, if the power supply voltage Vbus is set to a small and constant value, the required output voltage EM cannot be obtained even if the voltage drop ED of the power semiconductor T is zero, and the thrust and propulsion speed of the linear motor LM are not obtained. There is a risk of shortage.

Therefore, in the present embodiment, the predetermined secondary voltage of the transformer 26 is supplied to the driver DV2 by performing the switching control of the tap 28 based on the speed SPn and the thrust Fn of the current table TB calculated by the necessary characteristic calculator 30. Apply and change to the power supply voltage Vbus suitable for the speed SPn and thrust Fn of the current table TB.
That is, when the necessary characteristic calculator 30 calculates the large speed SPn and thrust Fn of the table TB, the secondary side voltage of the transformer 26 is set to a large value and the power supply voltage Vbus is changed to a large value by switching control of the switching tap 28. When the required characteristic calculator 30 calculates the small speed SPn and thrust Fn of the table TB, the secondary side voltage of the transformer 26 is set to a small value and the power supply voltage Vbus is changed to a small value by the switching control of the switching tap 28.

As described above, in the present embodiment, the power supply voltage Vbus of the driver DV2 is not set to a constant value, but is changed to the necessary minimum power supply voltage Vbus based on the speed SPn and thrust Fn of the table TB at the current operating point DN. Energy saving can be achieved.
Further, since the capacity of the power semiconductor T is not increased and the heat dissipation heat sink can be reduced in size, the driver DV2 can be reduced in size and weight.

Furthermore, a circuit according to a third embodiment of the present invention will be described with reference to FIG. The same components as those shown in FIGS. 2 to 4 are denoted by the same reference numerals, and the description thereof is omitted.
In the present embodiment, the driver DV2 is connected to the power supply voltage Vbus via the power supply voltage semiconductor TP, the amplifier 34 that controls the power supply voltage semiconductor TP by linear drive, the necessary characteristic calculator 30, and this requirement A control signal generator 36 that outputs a control signal Su to the amplifier 34 based on the result calculated by the characteristic calculator 30 is provided. The power supply voltage semiconductor TP is connected in parallel with the smoothing capacitor CO. A comparator 38 that compares the power supply voltage Vbus and the control signal Su is connected between the control signal generator 36 and the amplifier 34.
The required characteristic calculator 30 of this embodiment corresponds to the required characteristic calculator of the present invention, and the control signal generator 36 corresponds to the drive control means of the present invention.

Next, the operation of this embodiment will be described.
When the required characteristic calculator 30 calculates the large speed SPn and thrust Fn of the table TB, the control signal Su is output from the control signal generator 36 to the amplifier 34 based on the speed SPn and thrust Fn, and the signal amplified by the amplifier 34 As a result, the power supply semiconductor TP is driven and controlled to generate a small voltage drop. As a result, the power supply voltage Vbus is changed to a large value. Further, when the necessary characteristic calculator 30 calculates the small speed SPn and the thrust Fn of the table TB, the power supply voltage semiconductor TP is driven and controlled by the control signal Su output from the control signal generator 36 to the amplifier 34, and a large value voltage A descent occurs. As a result, the power supply voltage Vbus is changed to a large value.

As described above, this embodiment also changes the power supply voltage Vbus of the driver DV2 to the minimum necessary power supply voltage Vbus based on the speed SPn and the thrust Fn of the table TB calculated by the necessary characteristic calculator 30 without setting the power supply voltage Vbus of the driver DV2. Therefore, energy saving can be achieved.
In addition, since the capacity of the power supply voltage semiconductor TP is not increased and the heat dissipation heat sink can be reduced in size, the driver DV2 can be reduced in size and weight.

In this embodiment, the power supply voltage semiconductor TP is controlled by linear drive using the amplifier 34. However, if the power supply voltage semiconductor TP is controlled by PWM drive, power consumption is reduced and further energy saving is achieved. Can be promoted.
Further, if the linear guide LG of the positioning table device 2 adopting the driver DV1 of the second embodiment and the driver DV2 of the third embodiment is configured with an air bearing, high-precision positioning control can be expected.

It is a figure which shows the circuit which drives the electric power semiconductor of the driver of 1st Embodiment which concerns on this invention. It is a figure which shows the circuit which changes the power supply voltage of the driver of 2nd Embodiment which concerns on this invention. It is a figure which shows the structure of the power supply part of the driver of 2nd Embodiment. It is a figure which shows the characteristic map of the thrust-propulsion speed of the linear motor which the required characteristic calculating means based on this invention has memorize | stored. It is a figure which shows the circuit which changes the power supply voltage of the driver of 3rd Embodiment which concerns on this invention. It is the figure which showed the principal part of the precision positioning device which concerns on this invention by planar view. It is the figure which showed the precision positioning device from the A direction of FIG. It is the schematic which shows the structure of the linear motor of a precision positioning device. It is a figure which shows the circuit structure of the driver connected to the armature coil of the linear motor by which star connection was carried out.

Explanation of symbols

2 Positioning table device (precision positioning device)
4 base 6 guide rail 10 slider 12 stator 14 permanent magnet 16 mover 18 armature coil 20 output current detector 22 power semiconductor drive converter 26 transformer 28 tap 30 required characteristic calculator 32 control signal generator 34 amplifier 36 control Signal generator DV1, DV2 Driver LG Linear guide LM Linear motor MM Magnet array T, Uu, Ud, Vu, Vd, Wu, Wd Power semiconductor TB Table TP Power supply voltage semiconductor Vbus Power supply voltage

Claims (7)

A linear guide that guides the table on the base so as to be movable in a linear direction, a linear motor that travels the table guided by the linear guide in the linear direction, and an electric power that controls drive of the linear motor A driver having a semiconductor, and the linear guide includes a guide rail fixed on the base and a slider mounted on the guide rail and mounted on the guide rail. A stator having a magnet row in which a plurality of permanent magnets having different polarities are arranged in parallel and fixed on the base, and a coreless type fixed to the table and provided with a thrust in cooperation with the magnet row In a precision positioning device as a brushless DC motor provided with a mover having an armature coil,
Traveling state determining means for determining a traveling state of the table;
When it is determined that the table is traveling in an acceleration / deceleration state by the traveling state determining means, the power semiconductor of the driver is driven by pulse width modulation, and the table is driven at a constant speed by the traveling state determining means. A precision positioning apparatus comprising: a power semiconductor drive changing unit that linearly drives the power semiconductor when it is determined that the power semiconductor is in operation.   The traveling state determination means determines whether the table is traveling in an acceleration / deceleration state or whether the table is traveling at a constant speed according to a change in an output current value output from the driver to the linear motor. The precision positioning device according to claim 1, wherein the determination is performed.   The traveling state determination means determines that the table is traveling in an acceleration / deceleration state when the output current value is equal to or greater than a predetermined reference value, and the table is determined when the output current value is lower than the predetermined reference value. 3. The precision positioning device according to claim 2, wherein it is determined that the vehicle is traveling at a constant speed. A linear guide that guides the table on the base so as to be movable in a linear direction, a linear motor that travels the table guided by the linear guide in the linear direction, and an electric power that controls drive of the linear motor A driver having a semiconductor, wherein the linear guide includes a guide rail fixed on the base and a slider mounted on the guide rail and mounted on the lower surface of the table, and the linear motor is adjacent to the guide rail. A stator having a magnet array in which a plurality of permanent magnets having different magnetic pole polarities are arranged in parallel and fixed on the base, and a coreless fixed to the table and provided with a thrust in cooperation with the magnet array In a precision positioning device as a brushless DC motor provided with a mover having a type armature coil,
The power semiconductor of the driver is controlled by linear drive,
Necessary characteristic calculating means for calculating the present required characteristic of the linear motor;
A precision positioning apparatus comprising: a power supply voltage changing means for changing a power supply voltage of the driver based on a calculated value of the necessary characteristic calculating means.   The power supply voltage changing means includes a transformer for stepping down an AC voltage supplied from the outside, a switching tap connected between the secondary side of the transformer and the driver, and a control based on a calculation value of the necessary characteristic calculation means. 5. The precision positioning device according to claim 4, further comprising tap switching control means for performing switching control of the switching tap by a signal.   The power supply voltage changing means includes a power supply voltage semiconductor and drive control means for driving and controlling the power supply voltage semiconductor by a control signal based on a calculation value of the necessary characteristic calculation means. 4. The precision positioning device according to 4.   7. The precision positioning apparatus according to claim 6, wherein the drive control means drives the power supply voltage semiconductor by pulse width modulation.

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