JP2824785B2 - Linear motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a linear motor, and more particularly, to an MM (movable magnet) type linear motor that directly drives a precision positioning table or the like.

[Prior Art] The inventors of the present invention have disclosed in Japanese Patent Application No. 63-225357 that the logic circuit and the drive circuit can be simplified and the number of lead wires connecting the logic circuit, the drive circuit and each coil can be reduced. Such a linear motor was proposed. 10A is a structural diagram showing a main structure of a front part of a movable part and a fixed part of the above-described proposed linear motor, and FIG. 10B is a side view of FIG. 10A;
FIG. 10C is a connection diagram of a fixed portion of the linear motor shown in FIG. 10A. Referring to FIG. 10A, the linear motor includes a movable section 1 and a fixed section 2, and the movable section 1 includes a yoke 11 and a permanent magnet 12. The movable portion 1 is arranged so as to actually move in the left-right direction in FIG. 10A by a guide (not shown) via the fixed portion 2 and a fixed air gap 3. A table (not shown) is attached to the movable unit 1. The fixed part 2 is constituted by a core 21 and a coil 22. This coil 22 is U
Three-phase coils of phase, V-phase, and W-phase are arranged in order. No.
In the example shown in FIG. 10A, the V-phase and the W-phase are energized, and if the direction of the current is as shown in FIG. Become. Further, the coil 22 of the fixed part 2 is connected to u ₁ , v ₁ , w ₁ ,
u ₂ , v ₂ , w ₂ ,..., u ₁₅ , v ₁₅ , w ₁₅ , u ₁₆ , v ₁₆ , w ₁₆ . These coils u ₁ , v ₁ , w ₁ ,... U ₁₆ , v ₁₆ , w ₁₆ are connected as shown in FIG. 10C. That is, U-phase coils u _{1 to} u ₁₆ ,
A coil v ₁ to v ₁₆ of V phase, both the coil w ₁ to w ₁₆ of the W-phase all coils are electrically connected in series.

The right ends of the three-phase coils described above are terminals U, V, W, and the left end is a neutral point N at the neutral point N where all three phases are short-circuited.
The connection method is used. The terminals U, V, W are respectively connected to the drive circuit. The current supplied to the terminals U, V, W is controlled by this drive circuit, and the movable section 1 runs.

[Problems to be Solved by the Invention] As described above, in the proposed linear motor, the current applied to the three terminals U, V, and W may be controlled, so that the configuration of the control circuit can be simplified. However, since the current is supplied to all coils of each phase to be supplied with current, the current flows to a portion that does not contribute to running the movable portion 1, resulting in poor efficiency. In addition, the longer the stroke of the motor is, the more the efficiency is reduced. Therefore, there is also a disadvantage that it cannot be applied to a linear motor having a long stroke. Therefore, instead of all excitation method is conceivable method for energizing only the coil needed to provide a terminal in each of the phase coils e.g. u ₁ ~u _16. However, in such a case, although the efficiency is good, the number of lead wires and the number of power elements are required to be large, which causes a new problem that a circuit becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a linear motor capable of improving efficiency without complicating a circuit.

[Means for Solving the Problems] The invention according to claims 1 to 3 is an exciting coil comprising a movable portion provided with a permanent magnet, a core having a rectangular cross section and a conductor wound around the outer periphery of the core. A fixing part formed with
A position detection unit provided in the fixed unit, for detecting the position of the movable unit, and an area detection unit provided in the fixed unit, which detects that the movable unit is in a predetermined region and outputs a detection signal. The excitation coil has three phases, and the coils of each phase are wound around the outer periphery of the core for each pole, and the coils of each phase are all electrically connected in series for each phase, and are connected in series. The coils of each phase are Δ-connected, input terminals are provided at connection points of each phase and two of the connection points of each coil of each phase, and in response to a detection signal output from the area detection unit. This is a linear motor that switches the energizing section of each phase coil.

In the invention according to the second aspect, the position of the first input terminal of the two input terminals provided in the coils of each phase connected in series is such that the number of poles of the movable portion is A, and the number of poles of the fixed portion is A. When an even number B is set, (A + B) / 2 or (A + B + 2) / 2 from one end of each phase coil, and the position of the second input terminal is (A + B) / 2 or (A + B) / 2 from the other end of each phase coil. (A + B + 2)
/ 2.

In the invention according to the third aspect, the position of the first input terminal of the two input terminals provided in the coils of each phase connected in series is such that the number of poles of the movable part is A, and the number of poles of the fixed part is A. When the odd number B is set, (A + B + 1) / 2 is set from one end of each phase coil, and the position of the second input terminal is set to (A + B + 1) / 2 from the other end of each phase coil. .

[Operation] In the invention according to the first aspect, in addition to the three-phase input terminals, two of the connection points of the coils of each phase are provided with input terminals, and the output of the position detection sensor provided on the fixed part is provided. In response to the signal, the energized section of each phase coil is switched,
The control circuit and the drive circuit can be simplified, the number of lead wires for connecting each coil and the drive circuit can be reduced, and the efficiency can be improved. According to the second and third aspects of the present invention, the interval between the intermediate terminals is set to be longer than the length of the fixed portion. Fluctuation and speed change can be prevented.

[Embodiment of the Invention] Fig. 1A is a structural view showing a main structure of a front part of a movable part and a fixed part of a linear motor according to an embodiment of the present invention.
FIG. 1B is a side view of FIG. 1A, and FIG. 2 is a connection diagram of a fixing portion. Referring to FIG. 1A and FIG. 1B, the linear motor includes a movable section 1 and a fixed section 2,
Is composed of a yoke 11 and a permanent magnet 12. The movable section 1 is arranged so as to freely move in the left and right direction in FIG. 1A by a guide (not shown) via a fixed section 2 and a fixed air gap 3. A table (not shown) is attached to the movable unit 1.

On the other hand, the fixed part 2 is constituted by a core 21 and a coil 22, and is fixed to a mounting member (not shown) to form a uniaxial slide table.

More specifically, the yoke 11 of the movable portion 1 is made of a magnetic material so as to form a magnetic circuit of the permanent magnet 12, and needs a cross-sectional area that is not saturated with the magnetic flux of the permanent magnet 12. On the yoke 11, a predetermined number of permanent magnets 12 are arranged at regular intervals. In the example shown in FIG. 1A, a four-pole system in which four permanent magnets 12 are provided is used, and the polarity of each pole is such that an N-pole and an S-pole alternately appear. The core 21 of the fixing part 2 is formed so that its cross section is square as shown in FIG. 1B. On the outer periphery of the core 21,
The coil is formed by winding the conductor.

This is a three-phase system in which three coils, for example, u ₁ , v ₁ and w ₁ are provided per length of one pole of the permanent magnet 12. Method of connecting these coils, as shown in FIG. 2, the coil u ₁ of U-phase, u _2, u _3, ~, connected in series to all the u ₈ order. V
Phase and W-phase are connected in the same way. Further, these connected three-phase coils are connected so as to form a Δ connection, and terminals U ₁ , V ₁ and W ₁ are provided on the connection lines, respectively.

Further, u and coil u ₂ of U-phase _3, u ₆ respectively to the connection point u ₇ provided terminals U ₂ and U _3. Similarly, terminals V ₂ , V ₃ , W ₂ , and W ₃ are provided for the V phase and the W phase. Position providing these terminals takes the length of the quadrupole component between U ₂ and U _3. This length is the same as the number of poles of the movable part 1.

FIG. 3 is a structural diagram showing another embodiment of the present invention when the length of the fixed portion 2 is three times the length of the movable portion 1,
FIG. 4 is a connection diagram of the embodiment shown in FIG. Third
Figure, with reference to FIG. 4, in this example, are provided so that the distance U ₂ and U ₃ corresponds to the length of the quadrupole component. No.
This coil has 12 poles, whereas the coil shown in FIG. 1A has 8 poles.

FIG. 5 is a block diagram showing a drive circuit of a linear motor applied to the present invention. Referring to FIG. 5, this drive circuit drives a linear motor as a permanent magnet synchronous type three-phase AC motor. Then, the drive circuit directly connects to the linear motor and detects a linear scale 30 for detecting the position of the movable unit 1 and a three-phase AC suitable for the position of the movable unit 1 based on the position detected by the linear scale 30. A commutation circuit 31 for producing the motor, a movable part position detector 32 for obtaining a movable part position signal of the linear motor, and a terminal for supplying a three-phase alternating current in response to the movable part position signal, thereby energizing the linear motor. Switching circuit 33 for switching sections
And a connection terminal 35 for connecting the three-phase alternating current generated by the current circuit 31 to the linear motor 34 and the switching circuit 32.

6 and 7 are structural views showing the arrangement of the position detector.

Next, the operation will be described with reference to FIG. 5, FIG. 6, and FIG. In FIG.
Is at the left end, the movable part position detector a is OFF. At this time, the switching circuit is in the state shown in FIG. That, U-phase of the three-phase power supply is connected to the U ₁ and V _3,
The V phase is connected to V ₁ and W ₃ , and the W phase is connected to W ₁ and U ₃ , respectively. In this case, the fixed part coil u ₁ u ₂ u ₂ u ₄ u ₅ u ₆ v ₁ v ₂ v _{2
v 4 v 5 v 6 w 1} w 2 w 3 w 4 w 5 current flows through the w _6. That is, current flows in the section I shown in FIG. 6, and no current flows in the section I '. The movable portion 1 moves to the left by receiving a force due to the current flowing in the section I. When movable part 1 moves, linear scale
30 detects that position. Based on the detected position, three-phase commutation corresponding to the position of the movable unit 1 is performed by the commutation circuit 31, and a three-phase alternating current suitable for the position of the movable unit 1 is generated.
In this way, the movable section 1 keeps moving rightward.

When the movable part 1 comes to the position A indicated by the dotted line in FIG. 6, the movable part position detector a turns ON. When the movable part position detector a is turned on, the three-phase connection points U, V, and W are switched by the switching circuit. That is, U of the three-phase output is a terminal U ₁ and U ₂ , V is a terminal
V ₁ and V _2, W is connected to the terminal W ₁ and W _2. In this case, the coil u ₃ u ₄ u ₅ u ₆ u ₇ u ₈ v ₃ v ₄ v ₅ v ₆ v ₇ v ₈ w ₃ w ₄ w ₅ w ₆ w ₇ w ₈
Current flows through That is, a current flows in the section II shown in FIG. 6, and no current flows in the section II '. Until the movable section 1 reaches the left end in FIG. 6, current flows in this section II.

FIG. 7 is an arrangement diagram of the movable part position detector when the length of the fixed part 2 is three times the length of the movable part 1. Referring to FIG. 7, a movable part position detector b is further added at intervals slightly shorter than the length of movable part 1, and the switching circuit is controlled by both signals of movable part position detectors a and b. Similarly, when the length of the fixed portion 2 is three times or more the length of the movable portion, the movable portion position detectors may be added at intervals slightly shorter than the length of the movable portion 1.

FIG. 8 is a schematic diagram of a linear motor in which the intervals between the intermediate terminals U ₂ and U ₃ , V ₂ and V ₃ , and W ₂ and W ₃ are the number of poles of the movable part + the length of two poles. is there. This linear motor is established when the number of poles of the fixed part is even, and when the number of poles of the movable part is A and the number of poles of the fixed part is B, the length of the conduction sections I and II is (A + B + 2) / 2 Becomes In this case, since the overlapping energizing section of the energizing sections I and II is longer than the length of the movable section by two poles, the switching of the energizing section can be performed without setting the setting position of the movable section position detector so strictly. The inconvenience of thrust fluctuation and speed change does not occur.

FIG. 9 is a schematic diagram of a linear motor in the case where the distance between the intermediate terminals is set to the length of the number of poles of the movable portion 1 + 1. This linear motor is established when the number of poles of the fixed part is odd. When the number of poles of the movable part is A and the number of poles of the fixed part is B, the lengths of the conduction sections I and II are (A + B + 1) / 2. Becomes In this case as well, the same effect as the case shown in FIG. 8 can be obtained because the overlap current section of current sections I and II is longer than the length of the movable portion by one pole.

As described above, in this embodiment, the control circuit is simplified and the number of lead wires can be reduced by providing the switching circuit for switching the energized section and the movable portion position detector. Thereby, the winding resistance can be reduced. As a result, the voltage drop due to the winding resistance can be reduced, and the speed and efficiency of the linear motor can be improved. This embodiment is most suitable for a linear motor whose stroke is twice or more the length of the movable part.

[Effects of the Invention] As described above, according to the first aspect of the present invention, the number of lead wires for connecting each coil and the drive circuit can be reduced, and the drive circuit can be simplified. Efficiency can be improved without complication. Further, according to the second and third aspects of the present invention, it is possible to prevent a change in thrust and a change in speed when the energized section is switched.

[Brief description of the drawings]

FIG. 1A is a structural view showing a main part structure of a movable part and a fixed part of a linear motor according to an embodiment of the present invention, FIG. 1B is a side view of FIG. 1A, and FIG. 2 is a view of FIG. 1A. FIG. 3 is a structural diagram showing another embodiment of the present invention, FIG. 4 is a wiring diagram of another embodiment shown in FIG. 3, and FIG. 5 is a diagram showing the present invention. FIG. 6 and FIG. 7 are arrangement diagrams showing the arrangement of the position detectors, and FIG. 8 is a diagram showing the arrangement of the position detectors and the distance between the intermediate terminals. FIG. 9 is a schematic view of a linear motor when the length is set to +2 poles. FIG. 9 is a schematic view of a linear motor when the interval between the intermediate terminals is set to the number of poles of the movable part + 1 length. FIG. 10 is a structural view showing a main part structure of a movable portion and a fixed portion of a linear motor proposed by the present inventors, and FIG. Side view of the linear motor, FIG. 10C is a connection diagram in the fixed portion of the linear motor shown in FIG. 10A. In the figure, 1 is a movable part, 2 is a fixed part, 11 is a yoke, 12
Is a permanent magnet, 21 is a core, and 22 is a coil. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

(57) [Claims] 1. A movable part provided with a permanent magnet, a fixed part including a core having a rectangular cross section, and an exciting coil formed by winding a conductor around the outer periphery of the core; A position detection unit for detecting the position of the movable unit; and a region detection unit provided on the fixed unit, and detecting that the movable unit is in a predetermined region and outputting a detection signal, The excitation coil has three phases, and the coils of each phase are wound around the outer periphery of the core for each pole. The coils of each phase are all electrically connected in series for each phase, and are connected in series. The coils of each phase are Δ-connected, input terminals are provided at connection points of each phase and two of the connection points of each coil of each phase, and in response to a detection signal output from the area detection unit. Wherein the energized sections of the coils of the respective phases are switched. Data. 2. The position of the first input terminal of the two input terminals provided on the coils of each phase connected in series is such that the number of poles of the movable portion is A and the number of poles of the fixed portion is even B. (A + B) / 2 or (A + B +) from one end of each phase coil
2. The second input terminal according to claim 1, wherein the position of the second input terminal is (A + B) / 2 or (A + B + 2) / 2 from the other end of each phase coil. Linear motor. 3. The position of the first input terminal of the two input terminals provided on the coils of each phase connected in series is such that the number of poles of the movable portion is A and the number of poles of the fixed portion is O. When you do
(A + B + 1) / 2 from one end of each phase coil, and the position of the second input terminal is (A + B +) from the other end of each phase coil.
2. The linear motor according to claim 1, wherein 1) / 2.