JP4552573B2 - Linear motor device - Google Patents

Description

  The present invention requires a long stroke, low heat generation and low thrust ripple in a linear motor device used in a linear motion mechanism of a precision device such as a semiconductor manufacturing device, a liquid crystal manufacturing device, or a machine tool, and selects a plurality of coils The present invention relates to a movable magnet type linear motor device that is excited and moves a permanent magnet.

Patent Documents 1 to 3 are movable magnet type linear motor devices that are used in linear motion mechanisms of precision devices such as semiconductor manufacturing devices, liquid crystal manufacturing devices, machine tools, etc., and selectively move a permanent magnet by exciting a plurality of coils. There is.
Japanese Patent Laid-Open No. 7-227078 JP 2000-341931 A JP 2002-199782 A

According to Patent Document 1, the position of the mover is estimated from the induced voltage of the coil generated with the movement of the permanent magnet, and the current phase is determined and the excitation coil is selected.
According to Patent Document 2, the position of the mover is specified by detecting the magnetic force of the permanent magnet for position sensing of the mover by the Hall element of the stator, and the current phase is determined and the excitation coil is selected.
According to Patent Document 3, the number of coils to be excited is switched between a constant speed state and an acceleration / deceleration state of the mover.
According to these Patent Documents 1 to 3, although the current phase determination method, the excitation coil selection method, and the excitation coil number determination method are different, the configuration of the switch unit that performs excitation ON / OFF is the same. Hereinafter, the linear motor device having the configuration of the switch part of the related art will be described.

FIG. 6 is an overall configuration diagram of a conventional linear motor device.
In the figure, 1 is a mover, 2 is a permanent magnet, 10 is a stator, 11 is a coil, 13 is a current amplifier, 14 is a position detecting means, 15 is a controller, and 20 is a switch unit.
FIG. 7 is a diagram showing a current pattern supplied from the current amplifier 13 to the stator 10. In the figure, 101 is a U-phase current, 102 is a V-phase current, and 103 is a W-phase current.
8 and 9 are diagrams showing coil excitation patterns at positions A and B in FIG. In the figure, 12 is a neutral point of the coil 11, and 21 is a switch circuit.
The mover 1 includes a permanent magnet 2 that forms a plurality of field magnetic poles. The mover 1 can be moved relative to the stator 10 via a predetermined gap by a support mechanism (not shown). The stator 10 includes a plurality of coils 11 that form a three-phase armature. The coils 11 are arranged with an electrical angle shifted by 120 degrees between the phases. The starting end of the coil 11 is connected to a three-phase power line to which currents 101, 102, and 103 are supplied. The terminal end of the coil 11 is connected to the switch unit 20, and is connected to the switch circuit 21 (FIG. 8) inside the switch unit 20. Further, all the terminal ends of the switch circuit 21 are connected inside the switch unit 20 to form a neutral point 12.
The controller 15 generates a current phase and amplitude command value based on the mover position information of the position detector 14 and the actual current information obtained by the current detector (not shown). The current amplifier 13 supplies currents 101, 102, and 103 to the coil 11 according to the current command value. Further, the controller 15 selects the coil 11 to be excited based on the mover position information of the position detecting means 14 and passes a coil selection signal to the switch unit 20. Here, for the position detection means 14, for example, a Hall element, a linear encoder, a laser interferometer, or the like is used. The switch circuit 21 (FIG. 8) uses a semiconductor switching element, such as a triac, that can turn on and off the current at a high speed based on a coil selection signal.

Next, a method for selecting a coil to be excited will be described.
FIG. 8 shows the relative positional relationship between the permanent magnet 2 and the coil 11 at the position A in FIG. 7 and the ON / OFF state of the switch circuit 21. The number of coils excited by the switch circuit 21 is three for each phase. As shown in the figure, when the switch circuit 21 is turned on, a current in the direction of the arrow (black) shown in the figure flows through the coil 11. Due to the action of the current flowing through the coil 11 and the magnetic flux density of the gap generated by the permanent magnet 2, the mover 1 moves by generating a thrust in the direction (white arrow) based on the Fleming left-hand rule.
FIG. 9 is a diagram in which the mover 1 is moved about 120 degrees in electrical angle from the position of FIG. 8 to the right side. FIG. 9 shows the relative positional relationship between the permanent magnet 2 and the coil 11 at the position B in FIG. 7 and the ON / OFF state of the switch circuit 21. As in FIG. 8, the number of coils excited by the switch circuit 21 is three for each phase, but the V-phase coil 11 is excited by being shifted by one in the moving direction of the mover 1. The timing at which the excited V-phase coil 11 is switched is when the V-phase current 102 is exactly zero, and is at the position C shown in FIG. Thus, when the currents 101, 102, 103 of each phase are zero from minus to plus, the coil 11 to be excited is switched, and a predetermined thrust is generated in the mover 1.
In the linear motor device according to the related art configured as described above, the current is supplied only to the portion facing the mover, so that the generated copper loss for a predetermined thrust can be reduced. Furthermore, since it is not necessary to supply an extra current for a predetermined thrust, the capacity of the current amplifier can be reduced and the linear motor device can be made inexpensive.

An induced voltage is generated between the starting end and both ends of the exciting coil selected in the linear motor device of the prior art as the permanent magnet of the mover moves. However, when three coils are excited for each phase as shown in FIGS. 8 and 9, there is a difference in the induced voltage between the coil at both ends of the mover or at a position away from the coil and the coil located inside the mover. As a result, a circulating current as indicated by the dotted arrow in the figure was generated. As a result, the following problems occurred.
(1) Since the circulating current flows between the coils, it cannot be detected by current detection means provided near the current amplifier. This means that the circulating current cannot be controlled. For example, when an attempt is made to move the mover at a constant speed by speed control, the circulating current flows between the coils while changing between positive and negative, and a braking force that changes positively and negatively is generated in the mover. This braking force became a so-called thrust ripple, and caused a speed ripple on the mover.
(2) In order to move the mover at a constant speed, a thrust that overcomes the braking force of (1) must be generated. As a result, an extra current for generating the thrust had to be supplied, and the generated copper loss increased.
(3) In order to avoid the above problems (1) and (2), if only the coil located inside the mover is excited, no difference in induced voltage occurs and no circulating current flows. However, since the number of coils to be excited is reduced, the amount of current supplied must be increased for a predetermined thrust, and the generated copper loss is increased.
In addition to the above-described problems, when trying to apply to an application having a long stroke, the following other problems occur.
(4) If the stroke is long, the stator length becomes long and the number of coils also increases. In the conventional linear motor device, the same number of switch circuits as the number of coils are required, so that the number of switch circuits is increased. As a result, it became an expensive device.
(5) With the increase in the number of switch circuits, the number of wiring between the switch circuit and the coil and between the switch circuit and the controller also increased. The number of wires became enormous and the device became more and more expensive.
The present invention has been made in view of such a problem, and in a movable magnet type linear motor device that moves a permanent magnet by selectively exciting a plurality of coils, the coil is irrespective of the number of coils to be excited. A linear motor device that can reduce thrust ripple and generated copper loss drastically without any circulating current between them, and can reduce the number of switch circuits and reduce the cost even if the stroke becomes longer is provided. The purpose is to do.

In order to solve the above problem, an invention according to claim 1 relates to a linear motor device, and supplies a current to the coil, a multiphase armature having a plurality of coils, a field having a plurality of permanent magnets, and the coil. In a linear motor device including a control unit that relatively moves the armature and the field, and a switch unit that selects the coil that supplies the current, the switch unit on each of a start end side and a terminal end side of the coil the provided a termination of their beginning and mating between the one and the plurality of coils of the same phase of each nearest neighbor coils, also, of its termination and mating with the other of the adjacent coils of the same phase recently Each of the start ends is connected with a crossover, and a plurality of first switch circuits for turning ON / OFF the current supply in the start end side switch portion are provided, and a plurality of first switch circuits for turning ON / OFF the current supply in the end side switch portion are provided. Second Comprising a switch circuit, the number of the first switch circuit Na, the number of the second switch circuit Nb, if the number of the coil was set to Nc,
Nc-M = Ia × Na = Ib × Nb
Here, M is the number of phases, and Ia and Ib are natural numbers.

According to the first aspect of the present invention, when the switch circuit of the switch part A and the switch part B provided on the start end side and the end end side of the plurality of coils is turned ON, the coils between the ON switch circuits are connected in series and excited. It has come to be. Since a plurality of coils are connected in series and excited, no circulating current flows between the coils. Therefore, it is possible to eliminate the thrust ripple and excessive copper loss caused by the braking force generated in the conventional linear motor device. Further, by reducing the number of switch circuits of the switch part A and the switch part B, the cost can be reduced even in the case of a long stroke application.

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

FIG. 1 is an overall configuration diagram of a linear motor device according to a first embodiment of the present invention. 2 and 3 are diagrams showing excitation patterns of coils at positions A and B in FIG. Hereinafter, the same components will be described with the same reference numerals. In the figure, 16 is a controller, 17 is a crossover, 30 is a switch part A, 40 is a switch part B, 31 is a switch circuit A, and 41 is a switch circuit B.
First, a description will be given of a configuration in which the related art and the present invention have the same configuration.
The mover 1 includes a permanent magnet 2 that forms a plurality of field magnetic poles. The mover 1 can be moved relative to the stator 10 via a predetermined gap by a support mechanism (not shown). The stator 10 is composed of a plurality of coils 11 that form a three-phase armature. The coil 11 is disposed with an electrical angle of 120 degrees between the phases. The terminal end of the coil 11 is connected to the switch unit B40, and is connected to the switch circuit B41 inside the switch unit B40. Furthermore, in the switch part B40, the termination | terminus of all the switch circuits B41 is connected and the neutral point 12 is formed. The controller 16 generates a current phase and amplitude command value based on the mover position information of the position detection means 14 and the actual current information obtained by the current detection means (not shown). The current amplifier 13 supplies currents 101, 102, and 103 to the coil 11 based on the current command value. For the position detecting means 14, for example, a Hall element, a linear encoder, a laser interferometer, or the like is used.

Next, a description will be given of a different configuration between the conventional technology and the present invention.
The switch part A is inserted between the start end side of the coil 11 and the current amplifier 13, and the start end and the end point between the nearest in-phase coils are connected by a crossover 17. Further, the controller 16 selects a coil to be excited based on the mover position information of the position detecting means 14, and passes the coil selection signal not only to the switch unit B40 but also to the switch unit A30. For the switch circuits 31 and 41, a semiconductor switching element similar to the prior art, for example, a triac is used.
Next, a method for selecting a coil to be excited will be described.
2 shows the relative positional relationship between the permanent magnet 2 and the coil 11 at the position A in FIG. 7, and the ON / OFF states of the switch circuit A31 and the switch circuit B41. The number of coils excited by the switch circuit A31 and the switch circuit B41 is three for each phase. Here, one switch circuit A31 is ON and one switch circuit B41 is one. When the switch circuit A31 and the switch circuit B41 at the illustrated locations are turned on, a current flowing in the direction of the arrow (black) shown in FIG. That is, the coil 11 positioned between the switch circuit A31 and the switch circuit B41 that are turned on is connected in series through the crossover wire 17.
As the coil 11 is excited in series in this way, the mover 1 can move in the direction based on the Fleming left-hand rule (open arrow) by the action of the magnetic flux density by the permanent magnet 2 and move. .
FIG. 3 is a diagram in which the mover 1 is moved from the position of FIG. 2 to the right by about 120 degrees in electrical angle. FIG. 3 shows the relative positional relationship between the permanent magnet 2 and the coil 11 at the position B in FIG. 7, and the ON / OFF state of the switch circuit A31 and the switch circuit B41. As in FIG. 2, the number of coils excited by the switch circuit A31 and the switch circuit B41 is three for each phase, but the V-phase coil 11 is excited by shifting one in the moving direction of the mover 1. The timing at which the excited V-phase coil 11 is switched is when the V-phase current 102 is exactly zero, as in the prior art, and is at the position C shown in FIG. When the currents 101, 102, 103 of each phase are zero, which changes from minus to plus, the coil 11 to be excited is switched, and a predetermined thrust is generated in the mover 1.
As described above, in the linear motor device configured in the first embodiment, the connection between the coils to be excited is in series with respect to the problem of circulating current between the coils that causes an increase in thrust ripple and an increase in copper loss. By configuring the switch circuit and the coil so as to become, the problem is solved so that the circulating current does not flow.
In addition, the connecting wire 17 is added to the configuration of the first embodiment with respect to the prior art. However, in the actual stator manufacturing, the connecting wire 17 is patterned with a copper foil in a coil connection board (not shown). Therefore, there is no increase in workability due to the increase in the number of crossovers 17.

Next, a second embodiment will be described.
4 and 5 are diagrams showing excitation patterns of the coils at positions A and B in FIG. As in the first embodiment, a current flows in the direction indicated by the arrow when the switch circuit A31 and the switch circuit B41 shown in FIG. In FIG. 5, the mover 1 is moved to the right by about 120 degrees in electrical angle with respect to FIG. 4, and a plurality of V-phase coils are shifted to the right and excited. The second embodiment is different from the first embodiment in that the number of switch circuits A31 is Na, the number of switch circuits B41 is Nb, and the number of coils 11 is Nc.
Nc-M = Ia × Na = Ib × Nb
Here, M is the number of phases, and Ia and Ib are in a relationship of natural numbers.
4 and 5, Nc = 30, M = 3, Ia = 3, Ib = 3, Na = 9, and Nb = 9. In the first embodiment, the relationship of Nc = 18, M = 3, Ia = 1, Ib = 1, Na = 15, and Nb = 15 is satisfied so as to satisfy the above formula.
However, when Nc = 30 in the first embodiment, Na = 27 and Nb = 27.
That is, in the second embodiment, the number of switch circuits A31 and switch circuits B41 can be reduced to 1/3 as compared to the first embodiment.

As described above, by configuring the switch circuit and the coil so that the connection between the coils to be excited is in series with respect to the problem of circulating current generation between the coils, which causes an increase in thrust ripple and an increase in copper loss, The solution is to prevent circulating current from flowing. Furthermore, since the number of switch circuits can be reduced as compared with the first embodiment, the number of switch circuits can be reduced without increasing the number of switch circuits even for long stroke applications.
In the above embodiment, the position detection means is used. However, the position detection means is eliminated, the position of the mover is estimated based on the information of the induced voltage, and the excitation coil is selected. It goes without saying that the effect of the present invention can be obtained even if the exciting coil is selected by driving and the movable element is moved.
Moreover, although the example of one mover is shown on the stator, it goes without saying that the effect of the present invention can be obtained even if a plurality of movers are mounted. Further, two movers may be mounted on the stator, and these movers may be driven by independent control using two each of the switch part A, the switch part B, and the current amplifier.

  The present invention is applied to a linear motion mechanism of a precision device such as a semiconductor manufacturing device, a liquid crystal manufacturing device, or a machine tool that requires a long stroke, low heat generation, and low thrust ripple, thereby improving the accuracy and function of the device itself. Can be realized.

1 is an overall configuration diagram of a linear motor device according to a first embodiment of the present invention. It is a figure which shows the excitation pattern of the coil which concerns on the 1st Example of this invention. It is a figure which shows the excitation pattern of the coil which the needle | mover moved to the right 120 degree | times by the electrical angle from FIG. It is a figure which shows the excitation pattern of the coil which concerns on the 2nd Example of this invention. It is a figure which shows the excitation pattern of the coil which the needle | mover moved to the right 120 degree | times by the electrical angle from FIG. It is a whole block diagram of the linear motor apparatus of a prior art. It is a figure which shows the current pattern of 3 phases. It is a figure which shows the excitation pattern of the coil which is a prior art. It is a figure which shows the excitation pattern of the coil which the needle | mover moved to the right 120 degree | times by the electrical angle from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable element 2 Permanent magnet 10 Stator 11 Coil 12 Neutral point 13 Current amplifier 14 Position detection means 15 and 16 Controller 17 Crossover wire 20 Switch part 21 Switch circuit 30 Switch part A
31 Switch circuit A
40 Switch B
41 Switch circuit B
101 U-phase current 102 V-phase current 103 W-phase current

Claims (1)

A multi-phase armature having a plurality of coils, a field having a plurality of permanent magnets, a control means for supplying current to the coils and moving the armature and the field relatively, and supplying the current In a linear motor device having a switch unit for selecting the coil to be
The switch part is provided on each of the start end side and the end end side of the coil,
Each of the plurality of coils has its own end and the other end between one of the nearest in-phase coils, and its own end and the other end between the other of the nearest in-phase coils. Connect each with a crossover ,
The first end switch section includes a plurality of first switch circuits for turning on / off current supply, and the end switch section includes a plurality of second switch circuits for turning on / off current supply, and the first switch When the number of circuits is Na, the number of second switch circuits is Nb, and the number of coils is Nc,
Nc-M = Ia × Na = Ib × Nb
Where M is the number of phases and Ia and Ib are natural numbers
A linear motor device characterized by that.

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