JPH11252880A - Pm-type synchronous three-phase motor and stator structure of three-phase motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized, low-cost permanent magnet(PM)-type synchronous three-phase motor with a simple structure. SOLUTION: This PM-type three-phase synchronous motor 1 is provided with a stator 2 and a rotor 6. The stator 2 is provided with a phase-U plate- shaped salient pole 3, a phase-W plate-shaped salient pole 5, a phase-V plate- shaped salient pole 4, a phase-U coil Cu wound around a first spacer portion 13, and a phase-V coil Cv wound around a second spacer portion 14. First teeth T1 is protruded from the circumferential surface of the U-phase plate- shaped salient pole 3, second teeth T2 is protruded from the circumferential surface of the W-phase plate-shaped salient pole 5, and third teeth T3 is protruded from the circumferential surface of the V-phase plate-shaped salient pole 4. Respective teeth T1-T3 are positioned so that their phases are shifted from each another by 120 deg.. The rotor 6 is installed so that the rotor encircles the stator 2. Permanent magnets 8, 9 which are parts of the rotor 6 are placed facing opposite to the teeth T1-T3. Therefore, the rotor 6 undergoes relative rotation with respect to the stator 2 through energizing of the coils Cu, Cv.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a PM type synchronous three-phase motor and a stator structure of a three-phase motor.

[0002]

2. Description of the Related Art Conventionally, PM (Pe
Various types of synchronous motors are known. Here, FIG. 6 shows an example of the PM synchronous three-phase motor 31.

[0003] The stator 32 constituting the motor 31 is
A total of six plate-shaped salient poles 33A, 33B, 34A, 34B,
It is configured by overlapping and connecting 35A and 35B. The plate-shaped salient poles 33A and 33B form one pair (for convenience, referred to as U relative), and the plate-shaped salient poles 34A and 34B.
Form another pair (for convenience, referred to as V relative), and the plate-shaped salient poles 35A, 35B form another pair (for convenience, referred to as W relative). First U-phase salient pole 33A and second U
First spacer portion 36 located between phase plate-shaped salient pole 33B
Is wound with a U-phase coil Cu. A V-phase coil Cv is wound around the second spacer portion 37 located between the first V-phase plate-shaped salient pole 34A and the second V-phase plate-shaped salient pole 34B. First W-phase salient pole 35A and second W-phase salient pole 35
The W-phase coil Cw is wound around the third spacer portion 38 located between B and B.

[0004] Each of these plate-shaped salient poles 33A to 35B has four teeth T on its outer peripheral surface. Plate-shaped salient poles 33A-33B, 34A-34B belonging to the same pair,
The phases of the respective tooth portions T of 35A-35B are 180 degrees with each other.
Are staggered so as to deviate from each other. Further, the plate-shaped salient poles 33A to 35B of each phase are arranged such that the phases are shifted from each other by 120 °.

[0005] Such a stator 32 is surrounded by a rotor 39. The rotor 39 includes a plurality of permanent magnets 40 having different polarities on an inner peripheral surface. These permanent magnets 40 are arranged to face the respective teeth T. Therefore, when an alternating current is applied to the coils Cu, Cv, and Cw of each phase, the rotor 39 rotates relative to the stator 32.

[0006]

However, in the stator 32 of the conventional PM type synchronous three-phase motor 31, six plate-shaped salient poles 33A to 35B and three kinds of coils Cu, Cv, C are used.
w, the number of parts was large and the structure was complicated. Therefore, there have been many requests that the structure of the PM type synchronous three-phase motor 31 should be simplified, downsized, and reduced in cost by reducing the number of parts.

If this is configured as a PM type synchronous two-phase motor, it is possible to omit two plate-shaped salient poles and one kind of coil. However, it has been strongly desired that a three-phase motor 31 having excellent operability and the like can reduce the number of parts to the same extent or more.

The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a small-sized and low-cost PM type synchronous motor having a simple structure. Another object of the present invention is to provide a stator structure suitable for realizing the above-mentioned excellent PM-type synchronous three-phase motor.

[0009]

According to the first aspect of the present invention, a first plate-shaped salient pole and a second plate-shaped salient pole are provided.
A plate-shaped salient pole and a third plate-shaped salient pole; a first coil wound around a first spacer portion located between the first plate-shaped salient pole and the second plate-shaped salient pole; A second coil wound around a second spacer portion located between the two plate-shaped salient poles and the third plate-shaped salient pole; and a second coil protruding radially from a peripheral surface of the first plate-shaped salient pole. A first tooth portion, a second tooth portion radially projecting from a peripheral surface of the second plate-shaped salient pole, and a third tooth portion radially projecting from a peripheral surface of the third plate-shaped salient pole. And a first member arranged so that the phases of the respective tooth portions are shifted from each other by 120 °, and a polarity provided so as to surround the first member and arranged opposite the respective tooth portions. Including a plurality of permanent magnets, and a second member that moves relative to the first member by energizing the coils.
The gist is a three-phase synchronous motor.

According to a second aspect of the present invention, there is provided a U-phase plate-shaped salient pole,
A W-phase plate-shaped salient pole and a V-phase plate-shaped salient pole; a U-phase coil wound around a first spacer portion located between the U-phase plate-shaped salient pole and the W-phase plate-shaped salient pole; V wound around the second spacer portion located between the W-phase plate-shaped salient pole and the V-phase plate-shaped salient pole.
A phase coil, a first tooth portion radially projecting from a peripheral surface of the U-phase plate-shaped salient pole, a second tooth portion radially projecting from a peripheral surface of the W-phase plate-shaped salient pole, A third tooth portion radially protruding from the peripheral surface of the phase plate-shaped salient pole, and a stator arranged so that the phases of the tooth portions are shifted from each other by 120 °; and a stator surrounding the stator. And a rotor that includes a plurality of permanent magnets having different polarities disposed opposite to the respective tooth portions and that performs relative rotation with respect to the stator by energizing the respective coils.
The gist is a three-phase synchronous motor.

According to a third aspect of the present invention, in the second aspect, the plate-shaped salient pole has a plurality of teeth at positions that are rotationally symmetric. According to a fourth aspect of the present invention, in the second or third aspect, the current Iu ′ applied to the U-phase coil is provided.
And the current Iv ′ applied to the V-phase coil is expressed by the following equation: Iu ′ = Iu−Iw, Iv ′ = Iv−Iw (where Iu is a normal U-phase coil, a V-phase coil and a W-phase coil. U for a three-phase motor
(Iv is the current that should be supplied to the V-phase coil in the ordinary three-phase motor, and Iw is the current that should be supplied to the W-phase coil in the ordinary three-phase motor.) It is set to satisfy the condition represented by.

According to a fifth aspect of the present invention, there is provided the first plate-shaped salient pole,
A second plate-shaped salient pole and a third plate-shaped salient pole, a first coil wound around a first spacer portion located between the first plate-shaped salient pole and the second plate-shaped salient pole, A second coil wound around a second spacer located between the second plate-shaped salient pole and the third plate-shaped salient pole, and radially projecting from a peripheral surface of the first plate-shaped salient pole A first tooth portion, a second tooth portion radially protruding from the peripheral surface of the second plate-shaped salient pole, and a third tooth portion radially protruding from the peripheral surface of the third plate-shaped salient pole And the phases of the respective tooth portions are arranged so as to be shifted from each other by 120 °.

The operation of the present invention will be described below. According to the first aspect of the present invention, since the first member uses three plate-shaped salient poles and two types of coils, the number of components can be reliably reduced as compared with the related art. Therefore, the structure of the three-phase motor can be simplified, and downsizing and cost reduction can be achieved.

According to the second aspect of the present invention, three U-phase plate-shaped salient poles, W-phase plate-shaped salient poles and V-phase plate-shaped salient poles, and two types of U-phase coil and V-phase coil are used. Since the stator is used, the number of parts can be reliably reduced as compared with the conventional case. Therefore, the structure of the three-phase motor can be simplified, and downsizing and cost reduction can be achieved.

According to the third aspect of the present invention, the magnetic force acting between each tooth portion and the permanent magnet becomes uniform about the rotation axis of the rotor, so that the rotor is less likely to be eccentric, and as a result, Operability is improved.

According to the fourth aspect of the present invention, by setting the energization amount to a condition satisfying the above expression, the PM synchronous three-phase motor of the present invention having two types of coils is provided with three types of coils. It can be driven with the same performance as a normal PM synchronous three-phase motor.

According to the fifth aspect of the present invention, since three plate-shaped salient poles and two kinds of coils are used, the number of parts can be reliably reduced as compared with the conventional one. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Hereinafter, a PM synchronous three-phase servomotor 1 according to a first embodiment of the present invention will be described in detail with reference to FIGS.

Here, the PM of the present embodiment shown in FIG.
Prior to describing the structure and the like of the mold synchronous three-phase servo motor 1, the process by which the inventor came to the motor 1 will be described in detail below.

FIG. 2 (a) shows a first member (stator) of a conventional ordinary rotary type three-phase motor. The first member has salient poles at three locations, and three types of coils (U-phase coil Cu, V-phase coil Cv, and W-phase coil Cw) are wound around each salient pole. In the figure, white arrow φu indicates the direction of magnetic flux passing through U-phase coil Cu, φv indicates the direction of magnetic flux passing through V-phase coil Cv, and φw indicates the direction of magnetic flux passing through W-phase coil Cw. ing.

Here, assuming that the magnetic flux leakage from the first member is negligibly small, each coil C
For magnetic fluxes φu, φv, φw passing through u, Cv, Cw, the following equations 1 to 3 hold.

Φu = − (φv + φw) (1) φv = − (φu + φw) (2) φw = − (φu + φv) (3) That is, the magnetic flux passing through one specific coil is the other two. It can be understood that the relationship is equal to a value obtained by subtracting the sum of the magnetic fluxes passing through the coil.

The currents to be supplied to the coils Cu, Cv, Cw are Iu, Iv, Iw, respectively, and the rotation angles between the coils Cu, Cv, Cw and the second member side (rotor side) having magnets. Is θ, each coil Cu, Cv, C
The torques Tu, Tv, Tw that generate w are expressed by the following equations 4 to 6.

Tu = (dφu / dθ) × Iu (4) Tv = (dφv / dθ) × Iv (5) Tw = (dφw / dθ) × Iw (6) Hereinafter, only the W-phase coil Cw is used. To continue with the example,
With respect to the torque Tw generated by the W-phase coil Cw, the following equation 7 can be derived from the equations 3 and 6.

Tw = − (dφu / dθ) × Iw− (dφv / dθ) × Iw (7) Here, the W-phase coil Cw, which is a specific type of coil, is a W-phase salient pole that should be originally provided. In this case, a configuration of the motor which is substantially equivalent to Equation 7 will be considered. In the motor shown in FIG. 2 (b), the W-phase coil Cw is not wound around the W-phase salient pole, but the W-phase coil Cw1 is wound around the U-phase salient pole, and the W-phase coil is wound around the V-phase salient pole. The phase coil Cw2 is wound. W-phase coils Cw1, C
Since w2 is wound in the opposite direction to the U-phase coil Cu and the V-phase coil Cv, a current flows in the opposite direction. In such a motor, a current Iu is supplied to the U-phase coil Cu and a current Iv is supplied to the V-phase coil Cv.
And the current I is supplied to the W-phase coils Cw1 and Cw2, respectively.
If w is energized, the condition of Equation 7 can be satisfied,
Driving performance equivalent to that of a normal three-phase motor can be exhibited.

FIG. 2 (c) shows a configuration of a motor which has been further developed. In this motor, the W-phase coil Cw is
Not only are the salient poles omitted, but neither the U-phase salient pole nor the V-phase salient pole is wound. Instead, for the U-phase coil Cu not omitted, the current Iu-I obtained by subtracting the current that should be supplied to the omitted W-phase coil Cw.
w is energized. Further, a current Iv-Iw obtained by subtracting a current that should be supplied to the W-phase coil Cw is supplied to the V-phase coil Cv that is not omitted. Even with such a configuration, the condition of Expression 7 can be substantially satisfied, and a driving performance equivalent to that of a normal three-phase motor can be realized.

FIG. 3 schematically shows a main part of a linear motor in which a rotary type motor as shown in FIG. 2 (c) is linearly developed and the tips of the salient poles are directed in the same direction. It is shown. The first member (moving body) M1 in such a linear motor is used while being mounted on the second member (rail) R1. The second member R1 has a plurality of magnets MG laid on its upper surface. FIG. 3 (a)
, The magnet MG is laid in a direction perpendicular to the paper surface.

Here, as shown in FIG.
The tip of each salient pole in the member M1 has a phase difference of 1
It is arranged so as to be shifted in a predetermined direction as much as 20 °.
That is, the leading end of each salient pole is, so to speak, on one diagonal line of the first member M1. Also, the first member M
1 shift direction of the salient pole (that is, the traveling direction of the first member M1)
A1 and the laying direction of the magnet MG are set to be parallel.
If the current is supplied in this state, the first member M1 can be moved in the direction perpendicular to the plane of FIG.

Further, when the first member M1 and the second member R1 are again rotary-rotated with reference to the axis AX in FIG. 3A, the PM of FIG. 1B of the present embodiment is obtained.
A motor having a structure similar to the mold synchronous three-phase servomotor 1 can be obtained. The process by which the inventor arrived at the motor 1 is as described above, and the details thereof will be described below.

The stator 2 as the first member constituting the PM synchronous three-phase servomotor 1 of the present embodiment is a metal member made of iron or the like. The stator 2 includes a U-phase plate-shaped salient pole 3, a W-phase plate-shaped salient pole 5, and a V-phase plate-shaped salient pole 4.
The plate-shaped salient poles 3 to 5 are the constituent elements.

As shown in FIG. 1C, the U-phase plate-shaped salient poles 3 as the first plate-shaped salient poles are substantially gear-shaped having a plurality of (here, four) first teeth T1. It is a member of. Each of the first tooth portions T1 has the same shape, and all of them have a U-phase plate-shaped salient pole 3
Radially protrudes from the peripheral surface of the. The U-phase plate-shaped salient pole 3 is provided with these four first teeth T1 at positions that are rotationally symmetric with respect to the central axis.

The W-phase plate-shaped salient pole 5 as the second plate-shaped salient pole is also
A member having substantially the same shape as the U-phase plate-shaped salient pole 3,
Four second tooth portions T2 at rotationally symmetric positions with respect to the center axis
It has. The V-phase plate-shaped salient poles 4 serving as the third plate-shaped salient poles are also members having substantially the same shape as the U-phase plate-shaped salient poles 3, and four V-phase plate-shaped salient poles 4 The third
A tooth portion T3 is provided. Further, the W-phase plate-shaped salient pole 5 is provided with a columnar first spacer portion 13 at the center on one side, and the V-phase plate-shaped salient pole 4 is provided with a columnar second spacer portion 1 at the center on one side.
4 are protruded.

The U-phase plate-shaped salient pole 3 has a first spacer 13
The U-phase plate-shaped salient poles 5 are overlapped in a state where the end surfaces of the U-shaped plate-shaped salient poles 5 are brought into contact. The W-phase plate-shaped salient pole 5 has a second spacer portion 14
The V-phase plate-shaped salient poles 4 are overlapped in such a state that the end faces thereof are brought into contact with each other. The plate-shaped salient poles 3, 4, and 5 of the respective phases thus superimposed are connected to each other in a non-rotatable manner by connecting means such as caulking (not shown).

In this case, the tooth portions T1, T2, T3
Must be arranged so that the phases are shifted from each other by 120 °. The first spacer portion 1 located between the U-phase plate-shaped salient pole 3 and the W-phase plate-shaped salient pole 5
3, a U-phase coil Cu is wound. A V-phase coil Cv is wound around the second spacer portion 14 located between the W-phase plate-shaped salient pole 5 and the V-phase plate-shaped salient pole 4.

The rotor 6 as the second member constituting the three-phase servomotor 1 has a cylindrical yoke 7 and its yoke 7
And a plurality of permanent magnets 8 and 9 arranged on the inner peripheral surface of the main body. The first permanent magnet 8 has an N pole facing the stator 2 side, and the second permanent magnet 9 has an S pole facing the stator 2 side. The first and second permanent magnets 8 and 9 are arranged every other one and a total of eight. A certain gap is secured between the inner surface of each of the permanent magnets 8 and 9 and the tip surface of each of the salient poles 3, 4 and 5 to avoid contact.

However, the W-phase coil C to be wound originally
In this embodiment, w is not wound anywhere and is omitted from the stator 2. Therefore, in the three-phase servo motor 1, the number of coils is two (ie, two), which is one (ie, one) less than that of a normal one.

FIG. 4B shows a drive circuit 11 for driving the PM synchronous three-phase servomotor 1 of the present embodiment. The drive circuit 11 used in the present embodiment includes an inverter circuit 12 including six transistors Tr1, Tr2, Tr3, Tr4, Tr5, and Tr6 as a plurality of semiconductor elements. The transistors Tr1 and Tr2 form a U-phase transistor pair, the transistors Tr3 and Tr4 form a V-phase transistor pair, and the transistors Tr5 and Tr6 form a W-phase transistor pair.

The collector terminals of the transistors Tr1, Tr3, Tr5 are all connected to the positive side of the power supply. The emitter terminals of the transistors Tr2, Tr4, Tr6 are all connected to the negative side of the power supply. A connection point between the emitter terminal of the transistor Tr1 and the collector terminal of the transistor Tr2 functions as a first output terminal p1. A connection point between the emitter terminal of the transistor Tr3 and the collector terminal of the transistor Tr4 functions as a second output terminal p2. A connection point between the emitter terminal of the transistor Tr5 and the collector terminal of the transistor Tr6 functions as a third output terminal p3.

An on-delay circuit, not shown, is connected to the base terminals of the transistors Tr1 to Tr6 of the inverter circuit 12. Each of the on-delay circuits has a SIN through a comparator (not shown).
Signals from a generation circuit (not shown) and a triangular wave generation circuit (not shown) are supplied. As a result, each transistor Tr1
To Tr6 are turned on and off at a predetermined timing.

In FIG. 4B, the side marked with a black circle is the winding start portion of each of the coils Cu and Cv. Two types of coils not omitted (ie, U-phase coil Cu and V-phase coil C)
v), the starting portion of the U-phase coil Cu is connected to the first terminal t.
1, and the winding start portion of the V-phase coil Cv is a second terminal t2. A connection point formed by connecting the winding end portions of the coils Cu and Cv to each other is referred to as a third terminal t3. The first terminal t1 is connected to the output terminal p1 by the second terminal t1.
2 is the output terminal p2, and the third terminal t3 is the output terminal p2.
3 are connected to each other.

Therefore, when the transistors Tr1 and Tr6 are turned on, the U-phase coil Cu has a current flowing downward in FIG. 4B, that is, a forward current flowing from the winding start portion to the winding end portion. Flows. Transistor Tr
2, when Tr5 is on, the U-phase coil Cu
A current flowing in the upward direction in (b), in other words, a current flows in the reverse direction from the winding end to the winding start.

When the transistors Tr3 and Tr6 are turned on, the V-phase coil Cv has a current flowing downward in FIG. 4B, that is, a forward current flowing from the winding start portion to the winding end portion. Flows. Transistor Tr4
, Tr5 are on, the V-phase coil Cv
A current flowing in the upward direction in (b), in other words, a current flows in the reverse direction from the winding end to the winding start.

A current feedback loop is formed by using a current detector (not shown) for detecting the current of each of the U-phase coil Cu and the V-phase coil Cv for each phase instead of the drive circuit 11 as shown in FIG. It is also possible to employ a drive circuit that has been used.

Here, it is assumed that a normal three-phase servomotor is imagined, and a current that should be originally supplied to the W-phase coil Cw is Iw. Further, the U-phase coil Cu and the V-phase coil C in the three-phase servomotor 1 of the present embodiment
Currents to be supplied to v are denoted by Iu ′ and Iv ′, respectively. Further, a current to be supplied to the W phase is defined as Iw ′.

In the three-phase servo motor 1, a current Iu 'corresponding to Iu-Iw is supplied to the U-phase coil Cu. That is, a current obtained by subtracting a current Iw, which should be originally supplied to the W-phase coil Cw, from the current Iu, which should be supplied to the U-phase coil Cu in the ordinary three-phase servomotor, is supplied. Become. Also, for the V-phase coil Cv, Iv-Iw
The current Iv ′ corresponding to is supplied. That is, from the current Iv that should be energized to the V-phase coil Cv in the ordinary three-phase servomotor, the current Iw that should be energized to the W-phase coil Cw in the same motor is changed.
Will be supplied.

FIG. 4A shows currents Iu ', Iv', I
The temporal change of w ′ is shown for reference. According to this, the phase difference between the current Iu ′ and the current Iv ′ is 60
°, the phase difference between the currents Iv ′ and Iw ′ is 150 °, and the phase difference between the currents Iw ′ and Iu ′ is 150 °. Although the maximum values of the U-phase current Iu 'and the V-phase current Iv' are almost the same, only the maximum value of the W-phase current Iw 'is larger than them. Therefore, as the inverter circuit 12 in the present embodiment, it is necessary to select an inverter circuit having a standard that can withstand the load applied to at least the two transistors Tr5 and Tr6 constituting the W-phase transistor pair.

When the three-phase servomotor 1 is energized under the above-described conditions under the above-described configuration, the repulsive force or attractive force of the permanent magnets 8 and 9 acts between the rotor 6 and the stator 2. In this case, the repulsive force or suction force acts in a circumferential direction about the central axis, so that the rotor 6 can smoothly rotate relative to the stator 2 on the fixed side.

Therefore, according to the present embodiment, the following effects can be obtained. (1) In the PM synchronous three-phase servomotor 1, the stator 2 is constituted by using three plate-shaped salient poles 3, 4, 5 and two kinds of coils Cu, Cv. For this reason, the number of parts can be reliably reduced as compared with the conventional product. More specifically, as compared with a conventional ordinary PM type synchronous three-phase servomotor, three plate-shaped salient poles are sufficient, and one less coil is sufficient. By the way, in comparison with a conventional ordinary PM type synchronous two-phase servomotor, one less plate-shaped salient pole is sufficient. Therefore, the structure of the three-phase servo motor 1 can be reliably simplified, and downsizing and cost reduction can be achieved. Further, since the three-phase servomotor 1 is used, the operability can be improved as compared with a two-phase servomotor.

(2) In the case of the PM type synchronous three-phase servomotor 1 of this embodiment, the number of the plate-shaped salient poles 3, 4, and 5 is reduced.
It is simpler than a phase servo motor. In other words, the labor required for connecting the three plate-shaped salient poles 3, 4, and 5 by aligning them with a predetermined phase difference is the same as the labor required for performing the same operation for the six plate-shaped salient poles. This is because it is much smaller than.

(3) In this three-phase servomotor 1, each of the plate-shaped salient poles 3, 4, and 5 has four tooth portions T at positions where it is rotationally symmetric.
1, T2, and T3. Therefore, each tooth portion T1, T2, T3 and the permanent magnet 8,
9 becomes uniform around the rotation axis of the rotor 6. For this reason, the case where the tooth portions T1, T2, T3 are located at positions that are non-rotationally symmetric,
The rotor 6 is less likely to be eccentric as compared with a case where there is only one of the three salient poles 3, 4, and 5.

(4) In this embodiment, since the energization amount is set under the above preferable conditions, the torque Tw that would have generated the W-phase coil Cw of a normal three-phase servomotor was obtained.
Can be obtained. Therefore, the PM-type synchronous three-phase servomotor 1 of the present embodiment having two types of coils Cu and Cv has the same performance as a normal PM-type synchronous three-phase motor having three types of coils Cu, Cv and Cw. It can be driven. For this reason, problems such as generation of vibration during driving are also prevented.

(5) If the current feedback control is performed based on the results of current detection by the two-phase current detectors, it is not necessary to calculate the amount of current supplied to the W-phase coil Cw by calculation. Therefore, the three-phase servomotor 1 that is less susceptible to disturbance due to noise and that rotates smoothly with little vibration, that is, the three-phase servomotor 1 that has excellent driving performance can be realized. [Second Embodiment] Next, a PM synchronous three-phase servomotor according to a second embodiment of the present invention will be described with reference to FIG. Here, differences from the first embodiment will be mainly described, and the common points will be assigned the same member numbers only.

As shown in FIG. 5, the three-phase servo motor has basically the same components as the three-phase servo motor 1 of the first embodiment. However, the winding direction of the V-phase coil Cv, which is the second coil, is opposite to that of the first embodiment. Therefore, as shown in FIG. 5B, the connection point formed by connecting the winding end of the U-phase coil Cu and the winding start of the V-phase coil Cv to each other is the third terminal t.
The difference is that it is 1. Then, the third terminal t
3 is connected to the output terminal p3 of the inverter circuit 12.

Therefore, when the transistors Tr1 and Tr6 are turned on, the U-phase coil Cu has a current flowing downward in FIG. 5B, that is, a forward current flowing from the winding start portion to the winding end portion. Flows. Transistor Tr
2, when Tr5 is on, the U-phase coil Cu
A current flowing in the upward direction in (b), in other words, a current flows in the reverse direction from the winding end to the winding start.

When the transistors Tr3 and Tr6 are turned on, the V-phase coil Cv has a current flowing downward in FIG. 5B, that is, a current flowing in the reverse direction from the winding end to the winding start. Flows. Transistor Tr4
, Tr5 are on, the V-phase coil Cv has the shape shown in FIG.
, In other words, a forward current flows from the winding start portion to the winding end portion.

Incidentally, also in this three-phase servo motor,
Current I corresponding to Iu-Iw for U-phase coil Cu
There is no difference from the first embodiment in that u ′ is supplied and a current Iv ′ corresponding to Iv−Iw is supplied to the V-phase coil Cv. However, as is apparent from the temporal change of the currents Iu ′, Iv ′, and Iw ′ shown in FIG. 5A, the phase difference between the currents Iu ′, Iv ′, and Iw ′ is 120 °. There is a great difference from the first embodiment in a certain point. Further, only the maximum value of the current Iw 'of the W phase is not larger than the others, and the maximum value of each phase is substantially the same. This means that the load on the two transistors Tr5 and Tr6 constituting the W-phase transistor pair is smaller than that of the first embodiment.

Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects (1) to (5) of the first embodiment. (6) In this embodiment, the third terminal t3 is a connection point where the winding end of the U-phase coil Cu and the winding start of the V-phase coil Cv are connected to each other. Therefore, the number of terminals on the coil side is reduced by one compared with the motor configuration in which the number of terminals on the coil side is four in total. Therefore, it is possible to connect the terminals t1, t2, and t3 to the drive circuit 11 having three output terminals p1, p2, and p3 without excess and deficiency, respectively. Therefore, a general-purpose drive circuit 11 composed of six transistors Tr1 to Tr6 is sufficient as in a normal three-phase servomotor. Therefore, a small-sized and low-cost three-phase servomotor can be realized without increasing the number of components of the drive circuit 11 and without requiring the drive circuit 11 separately.

(7) The V-phase coil Cv, which is the second coil, has a current Iv 'substantially opposite in phase from the opposite direction.
Will be energized. Therefore, the direction of the current Iv 'itself does not change, and the phase difference between the currents Iu', Iv ', Iw' of each phase is also 120, as shown in FIG.
° and even. For this reason, the load on the two transistors Tr5 and Tr6 constituting the W-phase transistor pair is reduced, and thus each of the transistors Tr1 to Tr6 is reduced.
The load applied to the load becomes even. Therefore, the inverter circuit 1
It is not necessary to increase the specification of No. 2 in accordance with the maximum output peak of the transistors Tr5 and Tr6. as a result,
As compared with the case of the first embodiment, the inverter circuit 12 having a smaller standard can be selected, so that the cost can be further reduced.

The embodiment of the present invention may be modified as follows. The configuration in which the U-phase coil Cu is omitted or the configuration in which the V-phase coil Cv is omitted may be adopted instead of the first and second embodiments in which the W-phase coil Cw is omitted.

The present invention is not limited to the first and second embodiments in which the first member side is used as the stator 2 (that is, the fixed side) and the second member side is used as the rotor 6 (drive side).
It is of course also permissible to use the first member side as the drive side and the second member side as the fixed side.

The shapes of the tooth portions T1, T2, T3 are not limited to those of the first and second embodiments, and may be changed to other shapes. For example, the permanent magnet 8,
9 is small, the teeth T1, T2, T
3 may have a tapered shape.

The connection between the plate-shaped salient poles 3, 4, and 5 does not necessarily have to be performed by caulking, and may be, for example, bolting. Further, bonding using an adhesive, welding, and the like are also permitted.

◎ The spacers 13 and 14 include:
Those manufactured separately from the plate-shaped salient poles 3, 4, and 5 may be used. Further, the first spacer portion 13 may project from the U-phase plate-shaped salient pole 3, and the second spacer portion 14 may project from the W-phase plate-shaped salient pole 5. Note that all the plate-shaped salient poles 3, 4, and 5 may be configured to have a columnar structure so that parts can be shared. This is convenient for cost reduction.

The number of the tooth portions T 1, T 2, T 3 is not limited to four as in the first and second embodiments.
Or two, three, five, six
The number may be increased to seven or seven. Of course, a plurality of sheets is more preferable than a single sheet, and in the case of a plurality of sheets, a rotationally symmetric body is preferable.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) The PM synchronous three-phase motor according to any one of claims 1 to 4, wherein the motor is driven by being supplied with power from a drive circuit including an inverter circuit including a plurality of semiconductor elements. motor.

(2) In the technical idea 1, the winding start portion of the U-phase coil is a first terminal, the winding end portion of the V-phase coil is a second terminal, and the winding end portion of the U-phase coil is A connection point formed by connecting the winding start portion of the V-phase coil to each other as a third terminal, wherein each terminal is connected to three output terminals of the drive circuit, respectively. Three-phase motor. Therefore, according to the invention described in the technical idea 2, as a result, the load applied to each semiconductor element is equalized, so that an inverter circuit having a small standard can be selected, and the cost can be further reduced.

(3) Claims 2 to 4, technical idea 1,
2, the motor has a current detector for detecting a current of the U-phase coil and the V-phase coil for each phase, and a current detection by the current detectors for the two phases. A PM-type synchronous three-phase motor, which is a servomotor that performs feedback control based on a result. Therefore, according to the invention described in the technical idea 3, since it is not necessary to calculate the amount of current supplied to the omitted third-phase coil by calculation, it is less likely to be affected by disturbance due to noise.

[0068]

As described in detail above, according to the first to fourth aspects of the present invention, it is possible to provide a small-sized, low-cost PM type synchronous motor having a simple structure.

According to the third aspect of the invention, the operability of the PM type synchronous three-phase motor can be improved. According to the fourth aspect of the present invention, the motor can be driven with the same performance as that of a normal PM synchronous three-phase motor.

According to the fifth aspect of the present invention, it is possible to provide a stator structure suitable for realizing the above-described excellent PM type synchronous three-phase motor.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view of a PM synchronous three-phase servo motor according to a first embodiment, FIG. 1B is a left side view of the same motor,
(C) is an exploded perspective view of a stator of the motor.

FIGS. 2A and 2B are diagrams for explaining the process of conceiving the motor of the first embodiment, in which FIG. 2A is a schematic diagram showing a stator of a normal rotary three-phase motor, and FIGS.
(C) is a rotary type 3 in which one specific coil is omitted.
The schematic diagram showing the stator of the phase motor.

3 (a) is a schematic view showing a state in which the stator of FIG. 2 (c) is linearly developed, and FIG. b)
3A is a bottom view of FIG.

FIG. 4A is a circuit diagram of a drive circuit used in the motor of the first embodiment, and FIG. 4B is a graph showing a temporal change of each current supplied to the motor.

FIG. 5A is a circuit diagram of a drive circuit used in a motor according to a second embodiment, and FIG. 5B is a graph illustrating a temporal change of each current supplied to the motor.

6A is a schematic cross-sectional view of a conventional PM synchronous three-phase motor, FIG. 6B is a left side view of the motor, and FIG. 6C is an exploded perspective view of a stator of the motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... PM type synchronous three-phase motor, 2 ... Stator as 1st member, 3 ... U-phase plate-shaped salient pole as 1st plate-shaped salient pole, 4 ... U-phase plate-shaped salient as 3rd plate-shaped salient pole Pole, 5 ... W-phase plate-shaped salient pole as second plate-shaped salient pole, 6 ... rotor as second member,
8, 9 permanent magnet, 13 first spacer, 14 second
Spacer portion, Cu: U-phase coil as first coil, C
v: V-phase coil as a second coil, T1: first tooth portion,
T2: second tooth portion, T3: third tooth portion, Iu ': current applied to the U-phase coil (= Iu-Iw), Iv': current applied to the V-phase coil (= Iv-Iw).

Claims (5)

[Claims] 1. A first plate-shaped salient pole, a second plate-shaped salient pole, and a third plate-shaped salient pole, and a first plate-shaped salient pole located between the first plate-shaped salient pole and the second plate-shaped salient pole. A first coil wound around a spacer portion; a second coil wound around a second spacer portion located between the second plate-shaped salient pole and the third plate-shaped salient pole; A first tooth portion radially protruding from a peripheral surface of the plate-shaped salient pole;
A second tooth portion radially protruding from the peripheral surface of the plate-shaped salient pole; and a third tooth portion radially protruding from the peripheral surface of the third plate-shaped salient pole, and a phase of each tooth portion. A first member arranged so as to be shifted from each other by 120 °, and a plurality of permanent magnets having different polarities, which are provided so as to surround the first member and are arranged to face the respective tooth portions. And a second member that moves relative to the first member by energizing the coils. 2. A salient U-phase plate, a salient W-phase salient, and a salient V-phase salient pole, and a first salient pole located between the U-phase salient salient pole and the W-phase salient salient pole. A U-phase coil wound around a spacer portion; a V-phase coil wound around a second spacer portion located between the W-phase plate-shaped salient pole and the V-phase plate-shaped salient pole; A first tooth portion radially projecting from a peripheral surface of the plate-shaped salient pole, a second tooth portion radially projecting from a peripheral surface of the W-phase plate-shaped salient pole, and a periphery of the V-phase plate-shaped salient pole; A third tooth portion radially protruding from a surface, and a stator arranged so that the phases of the respective tooth portions are shifted from each other by 120 °; and a stator provided so as to surround the stator; A rotor that includes a plurality of permanent magnets having different polarities disposed opposite to the tooth portion and performs relative rotation with respect to the stator by energizing the coils. PM synchronous 3 to obtain
Phase motor. 3. The PM according to claim 2, wherein the plate-shaped salient pole has a plurality of teeth at positions that are rotationally symmetric.
Type synchronous three-phase motor. 4. The current Iu 'applied to the U-phase coil and the current Iv' applied to the V-phase coil are expressed by the following equations: Iu '= Iu-Iw, Iv' = Iv-Iw (where Iu Represents U in a case where a normal three-phase motor including a U-phase coil, a V-phase coil, and a W-phase coil is imagined.
(Iv is the current that should be supplied to the V-phase coil in the ordinary three-phase motor, and Iw is the current that should be supplied to the W-phase coil in the ordinary three-phase motor.) The PM-type synchronous three-phase motor according to claim 2 or 3, wherein the PM type synchronous three-phase motor is set so as to satisfy a condition represented by: 5. A first plate-shaped salient pole, a second plate-shaped salient pole, and a third plate-shaped salient pole, and a first plate-shaped salient pole located between the first plate-shaped salient pole and the second plate-shaped salient pole. A first coil wound around a spacer portion; a second coil wound around a second spacer portion located between the second plate-shaped salient pole and the third plate-shaped salient pole; A first tooth portion radially protruding from a peripheral surface of the plate-shaped salient pole;
A second tooth portion radially protruding from the peripheral surface of the plate-shaped salient pole, and a third tooth portion radially protruding from the peripheral surface of the third plate-shaped salient pole; A stator structure for a three-phase motor, wherein the three-phase motors are arranged so that their phases are shifted from each other by 120 °.