KR20030044165A - Position Sensor of Planar Linear Pulse Motor System - Google Patents

Abstract

PURPOSE: A position detecting apparatus of a linear pulse motor is provided to improve the performance and the credibility by converting a gear position of a stator into a signal by using a counter electromotive voltage generated when driving the linear pulse motor. CONSTITUTION: A position detecting unit(101) is provided on a motor main frame to detect a variation of a counter electromotive voltage. A zero crossing converting unit(102) converts an analog counter electromotive voltage signal generated by the position detecting unit(101) into a square wave. An encoder signal generating unit(103) converts into an encoder signal plural square waves transformed in the zero crossing converting unit(102). A line driver unit(104) transmits the encoder signal from the encoder signal generating unit(103).

Description

Position Sensor of Planar Linear Pulse Motor System

The present invention relates to a position detecting device of a linear pulse motor, and more particularly, by configuring the motor itself so as to convert the tooth position of the stator into a signal using a counter voltage generated when the linear pulse motor is driven. The present invention relates to a position detection apparatus for a linear pulse motor capable of detecting position information and speed of a motor without attaching a separate linear encoder.

In general, the linear pulse motor 1 is a motor of a drive type which moves the driving unit 3 in a planar motion on the tooth plate 2a formed in the stator 2, as shown in FIG. (2a) is a tooth form 2b, which is a stator having a regular array in the form of a matrix using a magnetizable material, and the tooth form consists of an equally spaced pitch 'P'.

The drive unit 3 moves along the tooth 2b of the tooth plate 2a, and the driving force is caused by the interaction between the current and the magnetic flux through the coil 5 on the tooth 2b of the tooth plate 2a. In order to obtain a symmetrical electromagnet (4) coiled in both directions and placed a permanent magnet (6) between them to connect each electromagnet (4), the electromagnet (4) is directed in the tooth direction of the tooth plate (2a) The poles were formed symmetrically and their ends were constructed by treating the poles.

In the case of the two-axis linear pulse motor 1, the two one-axis drive unit 3 is the same as that of the expansion by combining orthogonal shape. Although there is a difference in the actual shape of the linear pulse motor 1, the operation principle will be shown in the relationship as shown in Figs. 2a, b, c, d, e, f showing the tangential cross section between the drive unit 3 and the tooth plate 2a. Can be.

The drive unit 3 is composed of two horseshoe type electromagnets connected by permanent magnets as shown in FIG. 1 as described above.

The driving principle of the linear pulse motor 1 will be described below with an example of a two-phase motor.

The electromagnets 4 and 4a are denoted as core A + / A-phase or B + / B-phase, respectively, and the corresponding coils 5 and 5a wound on the electromagnets are denoted as A or B, and the arrows are magnetic fluxes. Indicates the direction of.

As shown in FIG. 2A, the two-phase bipola type linear pulse motor 1 has two phases A and B in both directions of the permanent magnet 6, and again has + and − two polarizations, respectively. This results in four phases, each of which has a 1/4 pitch phase difference from each other.

At this time, when + current flows through the coil A wound around the electromagnet as shown in FIG. 2B, the amount of magnetic flux becomes maximum on the A + phase where the magnetic flux generated by the permanent magnet 6 and the magnetic flux generated by the coil coincide with each other. The magnetic flux is minimal on A-phases with different directions.

At this time, the motor generates attraction in the A + phase where the amount of magnetic flux is maximum, and the core A moves in the direction of matching the A + phase and the tooth plate. On the other hand, since the same magnetic flux flows through the B + phase and the B-phase, the force in the horizontal direction does not appear to cancel each other in the core B.

Next, as shown in FIG. 2C, when the current supply to the coil A is stopped and the + current is applied to the coil B as well, the amount of magnetic flux is maximized on the B +. Accordingly, in the core B, the attraction force in the direction in which the B + phase coincides with the teeth of the tooth is generated. On the other hand, in the core A, the same amount of magnetic flux flows in the A + phase and the A-phase as in the core B, so that no horizontal force appears.

Then, when the reverse current is supplied to the coil A as shown in Fig. 2d, the maximum magnetic flux flows on the A-phase as opposed to the first stage. This generates a horizontal force in core A in the direction of matching the A-phase to the teeth of the tooth and the motor moves in the direction of the arrow.

Likewise, as shown in FIG. 2E, when the reverse current is applied to the coil B, the maximum magnetic flux flows on the B-phase and the B-phase moves in the direction corresponding to the teeth of the teeth. At this time, the horizontal force does not work in the core A.

Finally, when + current is flowed to the coil A again as shown in FIG. 2F, the motor moves in the direction in which the A + phase coincides with the teeth as in the beginning, thereby ending the movement of one pitch. Since two kinds of signals are input to the coil, it is called a two-phase driving method, and since the current direction is two directions, the positive direction and the reverse direction, it is called the bipolar method. The magnetic flux causes a vertical force between the drive motor and the flat plate, but the driving unit 3 floats due to the air bearing, and almost no friction causes the flat plate to move.

The air cap (void) 7 between the drive part 3 and the toothed flat plate 2b is usually about 0.00127 cm to 0.00254 cm.

In addition, the control system is composed of a linear loop motor (Close Loop) (not shown) which is a device for detecting a position or a speed in order to improve the performance of the motor or to monitor whether the motor is out of step.

As such a position detecting device, a linear encoder (not shown) is separately attached.

In general, in the case of a rotary motor used, a rotary encoder is attached, but in the case of a planar linear motor, a linear encoder that can be attached is extremely limited.

As described above, linear encoders using an optical principle or LVDT (Linear Voltage Differential Transformer) using a magnetic induction principle are mainly used as a linear encoder. The linear scale is composed of a linear scale band in which position information is indicated by a scale and a sensor head portion for optically reading the position scale.

Since the scale band is attached to the stator 2 of the linear pulse motor 1 and the sensor head part is mounted and moved in the driving part 3 of the motor, the inconvenience of having to mount the linear scale by the motor driving distance is accompanied. Straightness, smoothness, spacing or perpendicularity between the sensor head and the graticule act as important factors, which makes it difficult to precisely install the linear scale, thereby lowering the reliability of the product.

On the other hand, the LVDT (10) is a sensor using a magnetic induction principle is composed of two coil portion 12 wound around the iron core 11 of the cylindrical shape as shown in Figure 3 and the magnetic core 13 moving in the coil. .

When the magnetic core 13 is moved, an induction current is generated in the coil unit 12 by magnetic induction, and the difference between the induction currents generated in the two coils is used as position information.

Since the physical quantity corresponding to the difference in induced current is an analog signal, the positional accuracy is determined by the ability of the A / D converter to convert the analog signal into a digital signal, thus belonging to a relatively precise sensor, but when the driving distance is long, the winding coil Due to the technical problem of winding the entire sensor evenly, the long drive distance LVDT (10) has a disadvantage that can not be universalized.

Accordingly, the present invention is to solve the conventional problems as described above, an object of the present invention, by using the counter electromotive voltage generated when driving the motor to the motor main body configured to convert the position of the stator teeth into a signal The present invention provides a position detection apparatus for a linear pulse motor that monitors whether a motor is out of step and makes it easy to detect a position or speed, thereby improving the performance of the motor.

Another object of the present invention is to configure the motor body to detect the position of the motor, it is easy to install because the existing linear encoder is not used separately, and is not limited by the driving distance, it is also easy to planar drive motor It is to provide a position detection device of a linear pulse motor that can be applied.

In order to achieve the above object, the position detecting device of the linear pulse motor of the present invention includes a stator made of a tooth plate with a regular tooth processed, and the magnetic stator floats on a tooth plate to produce a constant directional motion by magnetic action. In addition to having an electromagnet having a plurality of cores corresponding to the teeth of the tooth plate, a coil is applied to the electromagnet and a permanent magnet is placed between the electromagnet and the electromagnet to form a magnetic flux and a magnetic field. A linear pulse motor comprising a drive unit for performing a planar axis movement from above, the linear pulse motor comprising: a position detecting unit provided in the motor body for detecting a change in counter electromotive voltage generated due to interaction with teeth of the stator according to driving of the drive unit; Analog counter voltage signal generated by the position detector Zero-crossing converting unit for converting the square wave, encoder signal generating unit for converting the plurality of square waves converted in the zero-crossing converting unit into an encoder signal, and line driving for transmitting the signal converted in the encoder signal generating unit at a long distance Characterized by including a base.

1 is a view showing the configuration of a linear pulse motor according to a conventional embodiment,

2a, b, c, d, e, f is a view showing the driving principle of a linear pulse motor according to a conventional embodiment,

3 is a view showing the structure of the LVDT used for the position detection of the linear pulse motor according to a conventional embodiment;

4 is a view showing the configuration of a position detection device for a linear pulse motor according to the present invention;

5 is a view showing the structure of a position detecting unit which is a configuration of a position detecting device of a linear pulse motor according to the present invention;

6A is a view showing the initial position of the position detector according to the generation of counter voltage in the position detection apparatus of the linear pulse motor according to the present invention;

6B is a view showing a quarter tooth width movement of a position detection unit according to generation of counter voltage in the position detection apparatus of the linear pulse motor according to the present invention;

Figure 6c is a view showing a half tooth width movement of the position detector according to the generation of the counter electromotive voltage of the position detection device of the linear pulse motor according to the present invention;

7 is a view showing a waveform diagram of a zero-crossing converting unit that is a configuration of a position detection device of a linear pulse motor according to the present invention;

8 is a view showing the timing of the encoder signal generator when using a plurality of cores of the position detection device of the linear pulse motor according to the present invention;

9 is a view showing the structure of a zero-crossing converting unit that is a configuration of a linear pulse motor according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1: motor body 2: stator

3: driving unit 100: position detecting device body

101: position detection unit 102: zero crossing conversion unit

103: encoder signal generator 104: line driver unit

Hereinafter, a position detecting apparatus for a linear pulse motor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the position detecting apparatus of the linear pulse motor according to the present invention will be described in detail with reference to the accompanying drawings, and at the same time adding reference numerals to the components of each drawing, the same components only on different drawings Although indicated, they have the same signs as possible.

4 is a view showing the configuration of the position detection device of the linear pulse motor according to the present invention, Figure 5 is a view showing the structure of the position detection unit that is a configuration of the position detection device of the linear pulse motor according to the present invention, Figure 6a Figure 6 shows the initial position of the position detector according to the generation of the counter electromotive voltage of the position detection apparatus of the linear pulse motor according to the invention, Figure 6b is a position detector according to the generation of the counter electromotive voltage of the position detection apparatus of the linear pulse motor according to the present invention Figure 6c is a view showing the movement of the tooth width of Figure 6, Figure 6c is a view showing the movement of the half tooth width of the position detector according to the generation of the counter electromotive voltage of the position detection device of the linear pulse motor according to the present invention, Figure 7 8 is a view showing a waveform diagram of a zero-crossing converting unit which is a configuration of a position detection device of a linear pulse motor according to the present invention, and FIG. 8 is a linear pulse motor according to the present invention. A view showing the number of cores using the timing signal generating portion encoder of the position detecting device, Fig 9 is a view showing a structure configuration of the zero crossing of the linear conversion portion pulse motor according to the present invention.

As shown in Figs. 4 to 9, the linear pulse motor main body 1 is composed of a stator 2, an air bearing (not shown), and a drive unit 3.

The stator 2 is composed of a tooth plate 2a on which regular teeth on a matrix are operated.

The teeth 2b may be provided with tooth bands so as to improve the positioning degree when the teeth 2b are not formed in the stator 2.

In addition, the tooth 2b is made up of pitch 'P' tooth width of the equal intervals.

The air bearing (not shown) allows the drive unit 3 to rise on the tooth plate 2a to form a gap 7.

The drive unit 3 is provided with a symmetrical electromagnet 4 and a core formed of a plurality of cores corresponding to the tooth 2b of the tooth flat plate 2a so as to generate a constant directional motion by magnetic action. 4) 4a is wound with coils 5 and 5a, and the toothed flat plate 2a is formed between the electromagnet 4 and the electromagnet 4a to form a permanent magnet 6 forming magnetic flux and magnetic field. It is installed above the surface.

In this state, the position detecting device main body 100 of the linear pulse motor main body 1 includes a position detecting unit 101, a zero cross conversion unit 102, an encoder signal generating unit 103, and a line. Driver unit 104 (Line Cross).

The position detecting unit 101 is provided in the motor body 1 to detect a change in the counter electromotive voltage generated due to interaction with the teeth of the stator 2 according to the driving of the driving unit 3.

Here, the position detecting unit 101 is composed of a stator 2 and a driving unit 3 which are the components of the motor body 1.

The zero crossing converter 102 receives an analog counter voltage signal generated by the position detector 101 and converts the square wave into a square wave.

In addition, the zero-crossing converting unit 102 is provided with a filter unit 102a to adjust the signal of the counter electromotive voltage according to the magnitude of the output voltage.

A zero-cross conversion circuit 102b for converting the signal of the counter electromotive voltage adjusted by the filter unit 102a into a square wave is provided.

The encoder signal generator 103 is configured to convert a plurality of phase signals converted by the zero-crossing converter 102 into A and B phase signals, which are general encoder signals.

The line driver 104 outputs and converts the signal converted by the encoder signal generator 103 into a signal that can be transmitted over a long distance.

In addition, a closed loop (not shown) is configured to read the position of the teeth 2b by receiving the signal output from the line driver unit 104 and to control the position.

In addition, the drive unit 3 is composed of a pair of at least one drive unit 3 for positioning each core of the drive unit 3 in accordance with the phase of the teeth 2b in order to improve the degree of positioning.

In addition, in the linear pulse type X and Y axis flat motors, the position detecting apparatus main body 100 as described above may be provided on the X axis and the Y axis, respectively.

Then, the operation of the position detection device of the linear pulse motor according to an embodiment of the present invention having the above configuration will be described in more detail with reference to FIGS. 4 to 9.

First, as shown in FIG. 5, the drive part 3 of the linear pulse motor main body 1 is operated. In this case, the driving unit 3 is composed of a plurality of cores wound around the permanent magnet 6 and the winding coils 5 and 5a, and functions to generate a plurality of counter voltages Vemf having a phase difference.

The anodes (+/-) of each of the cores 1, 2, 3, and 4 of the drive unit 3 have one tooth with respect to the tooth 2b of the stator 2 and one side with the teeth 2b, and the other side with the teeth. By placing them, the voltage due to magnetic induction can be detected as a sine wave.

On the other hand, each of the cores 1, 2, 3, and 4 fixes the teeth 2b of the stator 2 at the position of the phase divided by the total number of cores.

That is, as shown in Figure 5, when using the four cores look at the position of the core as follows.

The anode of core 1 has phase 0, phase 4/8,

Core 2 has phase 2/8, phase 6/8,

Core 3 has phase 1/8, phase 5/8,

Core 4 has phase 3/8, phase 7/8

Thus four cores are placed.

On the other hand, the permanent magnet (6) between the two cores so that the magnetic flux can be formed. The position detecting unit 101 configured as described above can detect the counter voltage as many as the number of cores when the motor is driven according to the phase difference.

First, the counter voltage Vemf output for one core is measured as shown in FIG.

Back EMF (Vemf) = -B × L × V

B is the magnetic flux density of the coil, L is the length of the coil, and V is the speed.

The magnetic flux density flowing through the coil in one core moving with respect to the stator 2 varies depending on the degree of coincidence between the teeth 2b of the stator 2 and the teeth of the core, as shown in Figs. 6A, B and C. It is characteristic of sine wave.

In addition, even when the vibration width of the sine wave changes depending on the speed at which the motor 1 moves, it has the same waveform as the counter electromotive voltage Vemf shown.

On the other hand, as described above, if each core is placed with a phase difference, the counter voltage Vemf as many as the number of cores is output with the phase difference.

As shown in FIG. 9, the zero crossing converter 102 includes a filter 102a and a zero crossing converter circuit 102b.

As shown in FIG. 7, the counter voltage Vemf is converted like a pulse waveform through the zero crossing converter 102.

In this case, the time constants R1 and C1 of the filter unit 102a may be adjusted according to the output voltage of the counter voltage Vemf.

Through this conversion, a pulse waveform according to the phase is generated as shown in FIG. 7.

The encoder signal generation unit 103 converts a plurality of pulse waveforms into A. B phase signals which are encoder standard signals.

Encoder A and B phase signals are 90 ° out of phase signals.

When four cores are used as shown in FIG. 5, core 1 and core 2 have a 90 ° phase difference between core 3 and core 4, and core 1 and core 3 have a 45 ° phase difference. The combined signal and the combined signal of cores 3 and 4 become a signal having a phase difference of 90 °.

Phase A = Pulse (1) XORPulse (2)

B phase = Pulse (3) XORPulse (4)

As shown in FIG. 8, a process of converting a plurality of phase signals into a signal having a 90 ° phase difference is shown.

In other words The n phase signals P (0) to P (n) calculated by are converted into encoder signals as follows.

A phase signal = (P (0) XORP (2 / n) XOR ((P (2) XORP (2 / n + 2) ... XOR (P2 / n-2) XOR P (n-2 ))

B-phase signal = (P (1) XOR (2 / n + 1) XOR ((P (3) XORP (2 / n + 3) ... XOR (P (2 / n-1) XOR P (n-1))

The line driver unit 104 outputs an encoder signal generated as a TTL signal into a signal for remote transmission.

In addition, in the linear pulse type X and Y axis flat motors, the present invention as described above can be provided in each of the X and Y axis directions.

The position detection apparatus of the linear pulse motor of the present invention described above is not limited to the above-described embodiments and drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical idea of the present invention. It will be apparent to those of ordinary skill in the art.

As described above, according to the position detecting apparatus of the linear pulse motor according to the present invention,

The motor main body is configured to convert the position of the stator teeth into a signal by using the counter electromotive voltage generated when the motor is driven, so that it is easy to monitor whether the motor is out of position and to easily detect the position and speed, as well as the position of the motor. By accurately detecting the information, the performance and reliability of the motor are improved, and since the existing linear encoder is not used separately, it is easy to install and can be easily installed on the X and Y plane drive motors. It has the effect of having no extensibility.

Claims (4)

This electromagnet is provided with a stator composed of a tooth plate with a regular tooth processed, and an electromagnet having a plurality of cores corresponding to the tooth of the tooth plate in order to float on the tooth plate of the stator and to produce a constant directional motion by magnetic action. In the linear pulse motor comprising a coil wound around the current applied to the current, the drive unit is composed of a permanent magnet placed between the electromagnet and the electromagnet to form a magnetic flux and a magnetic field, the axis of movement on the tooth plate, A position detection unit provided in the motor body for detecting a change in counter voltage caused by interaction with teeth of the stator according to driving of the driving unit; A zero crossing converter for converting an analog counter voltage signal generated by the position detector into a square wave; An encoder signal generator for converting a plurality of square waves converted by the zero-cross converter into an encoder signal; And a line driver unit for transmitting the signal converted by the encoder signal generator at a long distance. The method of claim 1, And the driving unit comprises at least one pair of driving units for dividing and positioning the cores of the driving units according to the phase of the teeth. The method of claim 1, The zero crossing converter includes a filter unit configured to adjust a signal of the counter electromotive voltage according to the magnitude of the output voltage; And a zero-cross conversion circuit for converting a signal of the counter electromotive voltage adjusted by the filter unit into a square wave. The method of claim 1, Wherein the tooth is a position detection device for a linear pulse motor, characterized in that consisting of a tooth band.