KR20010035213A - Brushless, coreless, ac type linear motor and linear motion apparatus having the same - Google Patents

Abstract

PURPOSE: A brushless planar air-core type AC linear motor and a linear driving system having the motor are provided to prevent the change of the thrust force and the speed when the operation by applying an AC current to the flat type air-core type linear motor. CONSTITUTION: The linear driving system(1) includes a driving section(2) and a servo driver(3) for driving the driving section(2). Cables(8,9) are provided to connect the driving section and the servo driver(3). The driving section(2) transfers the location signal at a linear scale, a signal about the relative position of a winding coil with respect to a permanent magnet, and a location information such as a limit switch signal to the servo driver(3) by using the scale cable. The servo driver(3) applies the current to the driving section(2) by using a power source cable(9) to realize the movement according to the relative position of the permanent magnet and the winding coil.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a brushless flat plate type AC type linear motor and a linear driving system including the brushless flat type AC type linear motor,

The present invention relates to a brushless flat plate type AC type linear motor and a linear driving system provided with the motor. More particularly, the present invention relates to a linear driving system having a brushless flat plate type AC type linear motor, And more particularly to a system for driving a vehicle.

Generally, a linear drive system is used for position and speed control according to rectangular coordinates such as semiconductor equipment and machine tools. In the case of machine tools, an iron core type AC type linear motor was mainly used. In the case of semiconductor equipment, air-core direct current type or pulse type linear motor was used. The drive system includes a current amplifier, a servo driver, and a controller, and is driven by coupling with a linear motor. Conventional air-core type servomotors are DC-type, and they maintain the phase difference of 90 ° to the magnetic flux density waveform of the permanent magnet according to the relative position of the permanent magnet and the winding coil. In order to apply current to the coil, .

Since the conventional linear motor as described above is driven by simulating a sinusoidal waveform in six steps, the thrust and the speed are changed when the step is switched.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an air-driven flat-plate AC-type linear motor and a linear drive system equipped with the linear motor in order to solve the above-mentioned problems and minimize a change in thrust or speed due to the movement of the slide.

1 is a perspective view of a linear drive system according to the present invention;

Fig. 2 is a diagram showing the connection relationship between the driving unit and the control unit in the driving system of Fig. 1

Figure 3 is a cross-sectional view of the drive system of Figure 1;

4 (a) and 4 (b) are a perspective view and a front view of a linear motor provided in the drive system of Fig. 1

5 is a front view of the mover provided in the linear motor of the drive system of Fig.

6 is a view for explaining the relative positions of the coils provided in the mover of the drive system of Fig. 1 and the permanent magnets provided in the stator;

Fig. 7 is a diagram showing the relationship between the relative positional change of the permanent magnet of the mover and the alternating current waveform of the coil of the mover provided in the linear motor of the drive system of Fig. 1, and also shows the relationship with the direct current waveform

DESCRIPTION OF THE REFERENCE NUMERALS

1: Linear driving system 2: Driving unit 3: Control unit (Servo driver)

4: Linear motor 5: Linear scale 6: Slide part

7: bearing guide 8, 9: cable 10: yoke 11: permanent magnet

12: mover 13: winding coil 14: Hall sensor 15:

The present invention provides an air-driven flat-plate AC type linear motor and a linear drive system provided with the linear motor. Instead of an iron core at the center of the winding coil, a nonmagnetic material having almost the same magnetic permeability as air is used. A sinusoidal waveform similar to the magnetic flux density waveform of the permanent magnet is applied to the winding coil and a sinusoidal waveform current having an electrical angle of 120 degrees is applied to the three coils. Also, in the linear drive system, the bearing guide is placed at the center of the linear motor, and the linear motor is disposed symmetrically to minimize the twisting by balancing the thrust generated by the two linear motors. Therefore, the force acting on the side of the linear scale used as the position measuring device is fundamentally prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a brushless flat plate type air-core AC type linear drive system according to an embodiment of the present invention. Referring to FIG. 1, the linear driving system 1 includes a driving unit 2 and a servo driver 3 for driving the driving unit 2. And cables 8 and 9 for connecting them are also provided.

Fig. 2 shows the relationship between the drive unit 2 and the servo driver 3 of the linear drive system. The driving unit 2 is provided with position information such as a signal of a hall sensor indicating a relative position between the position signal in the linear scale 5 and the winding coil 13 with respect to the permanent magnet 11 and a limit switch signal, (8) to the servo driver (3). The servo driver 3 applies a current to the driving unit 2 using the power cable 9 so as to realize a movement to move according to the relative position of the permanent magnet 11 and the winding coil 13. [

3 is a sectional view of the driving unit 2 of the linear driving system 1. Fig. Referring to FIGS. 1 and 3, the driving unit 2 includes a main body 15. A linear bearing guide 7 is provided at the center of the main body 15. The linear guide 7 supports the slide portion 6. The slide portion 6 moves in a straight line. The slide portion 6 is fixed to the mover 13 of the linear motor 4.

Two linear motors 4 of the same output are arranged symmetrically with respect to the bearing guide 7 as a center. The linear motor 4a and the slide portion 6 are provided with a position measuring device 5 provided with a linear scale. The position measuring device 5 equipped with a linear scale can use a normal one, and thus will not be described in detail here.

As described above, the linear motors 4 are provided on both sides of the bearing guide 7 to balance the thrust generated by the two linear motors 4, thereby eliminating the twisting applied to the bearing guides. Therefore, the force acting on the side surface with respect to the linear scale used in the position measuring device 5 is fundamentally prevented, and the deformation of the main body is minimized.

Figs. 4 (a) and 4 (b) show the linear motor 4 of the drive system 1. Fig. 1, 3, and 4, the linear motor 4 includes a stator and a movable element 13. [ The stator has a yoke 10 and a permanent magnet 11 in the shape of a "C". The permanent magnets 11 are configured so that N poles and S poles alternately appear in the longitudinal direction of the stator. In a state in which they face each other, the polarities are set so that they face each other. The coil set of the mover 13 is positioned between the facing permanent magnets 11 to drive the slide portion.

5 is a front view of the mover 12 of the brushless flat plate type air-core type AC linear drive system according to the present invention. The upper and lower lengths of the coils are shorter than those of FIG. The mover 12 is provided with two sets of three-phase coils, that is, six winding coils 13 and three hall sensors 14. [ The winding coil 13, the hall sensor 14 and the wire (wire) are fixed by the support body 12a. It is preferable that the support is made strong against bending and vibration by fixing the molded coil set and the Hall sensor. It is desirable that the material of the support be made so that the heat generated from the inside of the coil is well formed and at the same time the permeability is selected as a material similar to the air so that the attractive force by the permanent magnet does not occur. Therefore, when no current is applied, no electromagnetic force (cogging force) is generated between the coil set and the permanent magnet, so that the generation of the thrust can be uniformly controlled according to the driving of the slide portion when the coil is operated. As a material of such a support, for example, a thermally conductive epoxy such as epoxy mixed with aluminum is used.

6 is a conceptual diagram illustrating width dimensions of the poles of the coils 13a, 13b, and 13c of each phase and the permanent magnets 11, for example. 6, assuming that the width of one polarity of the permanent magnet 11 is a, the total width of the entire width 13a, 13b or 13c of the coil of any one phase is 4 / 3a, The coil line width forming the path through which the current flows is 1 / 3a. The Hall sensor 14 placed a distance of 5 / 6a from the start position of the coil to the center of the Hall sensor. In electrical angle, when the width 2a of the two polarities of the permanent magnet is 360 degrees, the width of the unit coil is 60 degrees. As a result, three permanent-magnet quadrupole coils are arranged so that the three coils and the hall sensors are arranged so as to have a phase difference of 120 °, respectively.

Fig. 7 shows waveforms of the currents applied to the coils of the respective phases in accordance with the positions of the coils 13a, 13b, and 13c. The current waveforms applied to the coils 13a, 13b, and 13c of the respective phases are sinusoidal waves. As shown in Fig. 7, the alternating current of each phase has a phase difference of 120 degrees. This current waveform is based on the position of the coil 13a. By applying the current of the above waveform, constant speed operation is possible.

The hall sensor performs the following functions. When the motor is driven, the position detector detects the position, calculates the relative position between the permanent magnet and the coil with this position information, and applies the appropriate current according to the calculation result. At this time, if the calculated value using the actual relative position of the permanent magnet and the coil and the value of the position measuring device deviates by more than 60 degrees from the electric angle, an inappropriate current is applied to the coil set, and the slide part proceeds very quickly in the unintended direction . In order to prevent this, the relative position value calculated using the position measuring device and the relative position value measured using the hall sensor are compared with each other to prevent malfunction of the slide part.

The advantage of applying an alternating current is readily apparent when compared to when applying a direct current. In the case of a conventional direct current type linear motor, as shown in FIG. 7, the position of the winding coil relative to the permanent magnet is detected by dividing the position of the winding coil into six sections using a Hall sensor, and a current do. So that current can be applied with a phase difference of 90 ° with respect to the magnetic flux density of the permanent magnet, and a current is applied stepwise according to the six sections. However, in the conventional case, the discontinuous points (a, b, c, d, e, and f) of the current are generated according to the respective sections, and accordingly, the thrust or the speed changes in the constant speed operation.

According to the configuration of the present invention as described above, by applying an alternating current to the flat plate-type air-core type linear motor, no change occurs in thrust or speed during constant speed operation. Since it is air-core type, the cogging force is not generated. Therefore, uniform thrust and speed can be ensured even when moving, and precise position control can be performed, so that it can be used for semiconductor equipment and precision measuring equipment.

Claims (5)

In a linear drive system having a stator and a mover, The stator includes a yoke having wings extending in parallel to each other and connected to each other by a connecting portion at one side and a pair of permanent magnets fixed to face each other at a position facing the wing portion, And the N poles and the S poles alternately face each other and are arranged so that different poles face each other, The mover includes a plurality of annular winding coils disposed between the permanent magnets and arranged side by side, wherein each of the winding coils has a plurality of coils wound around the permanent magnets, Brushless flat plate air - core AC - type linear drive system. The magnetic circuit according to claim 1, wherein the plurality of annular winding coils are divided into three phases, and a coil line width of each of the winding coils for dividing the magnetic flux between the facing permanent magnets is 1 / 3, and the total width of each of the winding coils is 4/3 of the width of one pole of the permanent magnet, and an alternating current having a phase difference of 120 degrees is applied to each phase. system. The linear drive system according to claim 1 or 2, further comprising a servo driver to apply an alternating current to each phase coil. 3. The linear drive system according to claim 1 or 2, wherein the mover is for supporting the coils of the respective phases, and comprises a support having a magnetic permeability similar to that of air. 5. The linear drive system according to claim 4, wherein the support is made of a thermally conductive epoxy resin material.