JPH05219701A - Variable reluctance motor with two salient-pole type rotor - Google Patents

Abstract

PURPOSE:To reduce iron losses such as a hysteresis loss, by further decreasing the minimum number of rotor teeth which can be provided on a rotor core. CONSTITUTION:This variable reluctance motor is provided with a nearly cylindrical stator core 12, three-phase excitation windings 14 wound around respective six stator teeth 20 of the stator core 12 with currents applied in a predetermined order, and a rotor core 16 rotated in the stator 12 by the sequential excitations of the excitation windings 14. The rotor core 16 is formed by laminating thin plates made of such a ferromagnetic material as silicon steel lamination. Each thin plate is provided with a pair of rotor teeth 24 in the axially symmetric positions of the outer periphery of the rotor core, protruding outside in the radial direction of the rotor core. The rotor core 16 is formed by laminating the respective adjacent thin plates while so rotating them mutually in a fixed drection by a certain angle that the respective two thin plates 22, which are provided at both ends of the rotor core in its axial direction, are given while rotating them mutually around the rotational center 0 of rotor core by the angle corresponding to a tooth width W of the rotor tooth 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable reluctance motor, and more particularly to a variable reluctance motor having an improved rotor structure for reducing iron loss by reducing the number of salient poles provided on the rotor side.

[0002]

2. Description of the Related Art A variable reluctance motor, which is known as a kind of step motor, is widely used as a servo motor or a direct drive motor. An example of a conventional general variable reluctance motor is shown in FIG. This variable reluctance motor has a stator core 1
Six protruding teeth 2 on the inner peripheral part (hereinafter referred to as stator teeth 2)
An excitation winding 3 is wound around each stator tooth 2. The rotor core 4 rotatably arranged inside the stator core 1 has four projecting teeth 5 (hereinafter, referred to as rotor teeth 5) that face each stator tooth 2 through a predetermined gap. Each of the stator core 1 and the rotor core 4 is formed by punching and laminating a ferromagnetic material such as a silicon steel plate (the laminated shape of the rotor core 4 is shown in (b)). The excitation winding 3 has I,
Currents of three different phases II and III are applied in a predetermined order, whereby the stator teeth 2 are sequentially excited, and the rotor teeth 5 are sequentially attracted by a magnetic attraction force, so that the rotor rotates in the direction opposite to the excitation direction.

As described above, in the conventional variable reluctance motor, the stator teeth of the stator core have an even number of the number of phases of the exciting current and are arranged at symmetrical positions with respect to the center of rotation of the rotor. Moreover, reducing the number of stator teeth of the stator core contributes to an increase in output. However, for example, when the stator core is provided with stator teeth having twice the number of phases of the exciting current as shown in FIG. 5, the magnetic path formed between the stator tooth and the rotor tooth during excitation is
It is inevitably longer than the case where four times as many stator teeth as the number of phases are provided. As a result, the generation area of eddy current due to the change of magnetic flux is expanded, and it is considered that the efficiency of the motor is deteriorated due to the increase of eddy current loss.

At this time, it is known that it is possible to reduce the hysteresis loss and the eddy current loss by reducing the frequency of the exciting current required for a predetermined rotation speed of the rotor core. Here, the angle at which the rotor rotates with respect to the exciting current of one pulse, that is, the step angle is
Since the number of teeth of the rotor core is inversely proportional to the number of teeth of the rotor core, the step angle increases and the pulse frequency of the exciting current required for one rotation of the rotor decreases. Therefore, by reducing the number of rotor teeth of the rotor core to reduce the frequency of the exciting current required for the same rotation speed, it is possible to reduce the loss such as the eddy current loss.

[0005]

An even number of rotor teeth is required to form a closed loop of the magnetic path between the stator teeth and the rotor teeth, so the theoretical minimum number of rotor teeth is two. Is. Therefore, it is conceivable to use the minimum number of two rotor teeth in order to reduce the loss. In this case, at least three-phase exciting currents are required to rotate the rotor, and the number of stator teeth at this time is six, which is twice the number of phases. In this structure, the width of the rotor tooth is made larger than that of the stator tooth, and when one rotor tooth is attracted to the stator tooth of the excitation phase, the side edge of this rotor tooth is adjacent to the stator tooth of the next excitation phase. When the structure is arranged in the vicinity, the rotor can theoretically rotate by switching the excitation phase. However, in practice, such a structure makes it impossible to hold the rotor at a fixed position during excitation, and cannot be used as a servomotor. This problem can be avoided if the widths of both the rotor teeth and the stator teeth are made equal, but the gap between the rotor teeth and the stator teeth of the next excitation phase becomes wide, so that the magnetic attraction force during excitation switching is The torque exerted on, that is, the tangential component force of the magnetic attraction force becomes extremely small, and there is a case where it cannot be self-started. For these reasons, in the conventional three-phase variable reluctance motor, the number of rotor teeth of the rotor core is four. Further, for the same reason, the minimum number of rotor teeth of the rotor core that can be installed is four or more for the variable reluctance motor having three or more phases.

The present invention has been eagerly devised and devised to solve such a problem, and its purpose is to further reduce the minimum installable number of rotor teeth formed in the rotor core of the rotor and to reduce the hysteresis. Reduce iron loss such as loss,
It is to provide a variable reluctance motor capable of improving efficiency.

[0007]

In order to achieve the above object, the present invention is directed to a motor housing and a motor housing fixed to the inside of the motor housing. A substantially cylindrical stator core having a plurality of stator teeth, and a plurality of exciting windings wound around the stator teeth of the stator core and capable of passing currents of different phases in a predetermined order are provided. A stator having magnetic poles sequentially formed on the stator teeth, and a rotor tooth rotatably arranged in the stator core of the stator and having a plurality of rotor teeth projecting radially outward at equal intervals on the outer circumference. The teeth are attracted to the magnetic poles that are sequentially formed on the stator teeth of the stator core to rotate, and the rotor core is concentrically fixed to the rotor core and is rotated to the motor housing. In a variable reluctance motor including a rotor having an output shaft that is supported so that, in the stator core, different exciting windings capable of passing currents of at least three phases are wound around each of the stator teeth. A plurality of ferromagnetic materials having at least six stator teeth having twice the number of phases, and the rotor core having a pair of rotor teeth projecting radially outward at axially symmetrical positions on the outer circumference. Is formed by laminating and adhering the thin plates of, the pair of rotor teeth have an outer diameter dimension on the outer peripheral surface that is smaller than the inner diameter dimension of the inner peripheral surface of the stator tooth of the stator core. Further, the tooth width on the outer peripheral surface is formed to be substantially the same as the tooth width on the inner peripheral surface of the stator tooth, and further, each of the thin plates arranged at both axial ends of the rotor core is To be placed in rotation with each other by the central angle corresponding to the tooth width of the motor teeth about a rotational center of the rotor core, it is laminated to rotate in a predetermined angle at a time mutually each adjacent lamina a fixed direction,
A rotor-two salient-pole variable reluctance motor having two rotor magnetic poles magnetically attracted to the stator teeth is formed by laminating the pair of rotor teeth of each thin plate.

According to a preferred embodiment of the present invention, the stator core includes the six stator teeth, and each of the stator teeth has three sets of exciting windings capable of passing a three-phase current. Provided is a rotor two salient pole type variable reluctance type motor wound so that currents of the same phase are applied to stator teeth at symmetric positions. At this time, each of the plurality of thin plates forming the rotor core has a center angle of 4 with respect to each of the tooth widths on the outer peripheral surfaces of the pair of rotor teeth.
It can also be formed to have dimensions corresponding to 5 °.

[0009]

[Operation] When a current of a predetermined phase is applied to the excitation winding of the stator,
The rotor teeth of the rotor are magnetically attracted to the stator teeth in the excitation phase of the stator, and due to the balance of the magnetic attraction forces, the rotor teeth are held at symmetrical positions with respect to the axial center line of the inner peripheral surface of the stator tooth. At this time, both axial end portions of the rotor teeth are located close to the non-excited phase stator teeth disposed on both sides of the excited phase, deviating from the directly facing positions of the excited phase stator teeth. When the current to the excitation winding is switched from this state to the next phase, the magnetic attraction force from the stator teeth of the next phase first acts on one axial end of the adjacent rotor teeth to rotate the rotor, and this rotation Accordingly, the rotor teeth are continuously acted on until they reach the other end of the remote rotor teeth in the axial direction. Due to this magnetic attraction force, the rotor rotates in a predetermined direction by a predetermined angle, and the magnetic flux distribution in the gap between the stator teeth and the rotor teeth is increased until the rotor teeth are opposed to the stator teeth of the next phase at the above-mentioned symmetrical positions. Because the state changes continuously,
Torque always occurs in the same direction with respect to the rotor. As described above, when the phase currents are sequentially switched, the torque due to the magnetic attraction force reliably and effectively acts on the rotor, and the rotor rotates in the same direction as the phase current switching direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail based on its embodiments with reference to the accompanying drawings. 1 is an end view of a stator core and a rotor core of a variable reluctance motor according to an embodiment of the present invention, FIG. 2 is a front view of a laminated plate member forming a rotor core of the motor of FIG. 1, and FIG. 3 is a motor of FIG. FIG. 4 is a plan view of the rotor of FIG. 4, and FIG. 4 is an operation explanatory view of the motor of FIG.

Referring to FIG. 1, a variable reluctance motor according to an embodiment of the present invention includes a motor housing 10.
And a substantially cylindrical stator core 12 fixed to the inside of the motor housing 10, and a plurality of exciting windings wound around the stator core 12 and capable of energizing in a predetermined order. A rotor core 16 which is composed of a stator composed of 14 and a laminated body of a ferromagnetic material such as a silicon steel plate and which is rotatably arranged in the stator core 12 by a rotating magnetic field generated by the sequential excitation of the exciting windings 14, and the rotor core 16 A rotor that is concentrically fixed to the motor housing 10 and that is rotatably supported by the motor housing 10 and that includes an output shaft 18 that extracts the motor output to the outside.

The stator core 12 is provided with six projecting teeth 20 (hereinafter referred to as stator teeth 20) on its inner peripheral surface at equal intervals (that is, one at every 60 ° mechanical angle) and projecting radially inward. Prepare The excitation winding 14 has a total of three windings wound in series with respect to each stator tooth 20 at an axially symmetrical position. Pulse currents of different three phases (indicated by I, II, and III in the drawing) are sequentially input to each excitation winding 14 via a drive circuit device (not shown). As a result, each stator tooth 20
Form the salient poles of the stator that are arranged in axial symmetry.

The rotor core 16 is formed by laminating thin plates 22 of a ferromagnetic material such as a silicon steel plate as described above (FIG. 2).
reference). As shown in FIG. 2, each thin plate 22 protrudes radially outward at an axially symmetrical position on the outer periphery (that is, at every mechanical angle of 180 °) and has a pair of projecting teeth 24 (hereinafter referred to as rotor teeth 24). Prepare The tooth width W on the outer peripheral surfaces of the pair of rotor teeth 24 has a dimension corresponding to a central angle of 45 ° in the example of the drawing.

When the rotor core 16 is formed by laminating the thin plates 22, the respective thin plates 22 are laminated in a state in which the adjacent thin plates 22 are rotated with respect to the rotation center O of the rotor in a certain direction and by a certain angle. As shown in FIG. 3, the mutual rotation angle is such that the adjacent thin plates 22 are mutually rotated so that the thin plates 22 arranged at both ends in the axial direction of the rotor core 16 have the tooth width W of the rotor teeth 24 (see FIG. 2). ), As long as they are arranged so as to rotate relative to each other about the center of rotation O. That is, the 21 thin plates 22 in the example of FIG.
The adjacent thin plates 22 are rotated by a central angle of 2.25 ° with respect to each other, and the rotor teeth 24 are regularly deviated with respect to the rotation center O. The rotor core 16 is formed by mutually adhering the thin plates 22 thus regularly arranged in rotation by an adhering process such as resin impregnation.

Further, each thin plate 22 forming the rotor core 16 has a central hole 26 (FIG. 2) which is concentric with the outer peripheral surface of the rotor tooth 24, and the output shaft 18 is fitted into the central hole 26. The output shaft 18 is formed on the rotor core 1 by means such as shrink fitting.
6 is fixed, and the rotor is formed (see FIG. 3). In this way, the laminated rotor teeth 24 of the rotor core 16 form two salient poles of the rotor that are magnetically attracted to the stator teeth 20 of the stator core 12.

The tooth width W of the outer peripheral surface of the rotor tooth 24 of the rotor core 16 is formed to be substantially equal to the tooth width W'of the inner peripheral surface of the stator tooth 20 of the stator core 12.
Therefore, the central angle is approximately 15 between the stator teeth 20.
A gap 28 is formed over an angle of .degree., And the exciting winding 14 is wound around each stator tooth 20 by utilizing this gap 28. In FIG. 1, the inner peripheral surface of the stator tooth 20 of the stator core 12 and the outer peripheral surface of the rotor tooth 24 of the rotor core 16 are shown in contact with each other, but in reality, a predetermined gap is formed between them. Needless to say.

The operation of the variable reluctance motor according to the present invention constructed as described above will be described below with reference to FIG. In FIG. 4, the motor housing 10, the rotary shaft 18, and the non-excitation phase excitation winding 14 are omitted. FIG. 4A shows a state in which an I-phase current is passed through the excitation winding 14 of the stator. In this state, the rotor teeth 24 of the rotor are
It is magnetically attracted to the I-phase stator tooth 20 of the stator and is held in a symmetrical position with respect to the axial center line of the inner peripheral surface of the stator tooth 20 due to the balance of the magnetic attraction force. At this time, the portions of the rotor teeth 24 in the vicinity of both ends in the axial direction are arranged so as to be radially overlapped with the side end portions of the stator teeth 20 of the other phases on both sides.

When the current to the exciting winding 14 is switched from this state to the II phase, the magnetic attraction force of the II phase stator tooth 20 first acts on one axial end portion of the rotor tooth 24 that is superimposed in the radial direction. The rotor is rotated clockwise, and with this rotation, the rotor teeth 24 are continuously acted on up to the other end of the remote rotor teeth 24. The magnetic attraction force causes the rotor to rotate clockwise from the state of FIG. 4A to the state of FIG. 4B by a mechanical angle of 60 °. During this time,
Since the state of the magnetic flux distribution in the gap between the stator teeth 20 and the rotor teeth 24 changes continuously, torque is always generated in the rotor.

Next, when the current to the excitation winding 14 is switched to the III phase, the rotor teeth 24 are attracted to the III phase stator teeth 20 in the same manner, and the rotor is further rotated clockwise from the state of FIG. 4B. Rotate by an angle of 60 °. in this way,
When the phase current is switched in the order of I, II, and III, the torque due to the magnetic attraction force acts on the rotor surely and effectively, and the rotor rotates in the same direction as the phase current switching direction. Therefore, in this variable reluctance motor, the pulse frequency of the phase current required for one rotation of the rotor is 2 Hz.
It is half that of the conventional variable reluctance type motor.

As the excitation method for switching the phase current, the conventional one-phase excitation method as described above can be used.
In order to generate the torque more effectively, the so-called 1-
It is preferable to adopt a two-phase excitation method. That is, in FIG. 4, immediately before the rotor enters the state of (a), at the moment when one end of the rotor tooth 24 in the axial direction starts to overlap in the radial direction on the side edge of the next phase II stator tooth 20, I The phase II current is passed without turning off the phase current. Next, when the rotor exhibits the state of (a), the current of the I phase is cut off and only the II phase is excited. By adopting such an excitation method,
The magnetic attraction by the II-phase stator teeth 20 is
4, from the side end of the one end in the axial direction to the state of the rotor (b) over the center angle range corresponding to 1.5 times the tooth width W (that is, the center angle 67.5 °), Acts as a clockwise torque. Moreover, this torque is in the range of the central angle of 7.5 °, and the I-phase and II-phase stator teeth 20
Therefore, the smoothness of rotation of the rotor is improved.

Although the structure of the three-phase variable reluctance type motor in which the rotor having two salient poles and the stator having six salient poles are combined has been described in the above embodiment, the present invention is not limited to this embodiment. Also, it can be applied as another 4-phase or 5-phase variable reluctance motor.

[0022]

As is apparent from the above description, according to the present invention, a plurality of ferromagnets having a pair of rotor teeth are provided so as to project a rotor core of a rotor radially outward at an axially symmetrical position on the outer circumference. Formed by laminating thin plates of material, each of which is arranged at both ends in the axial direction of the rotor core is arranged so as to rotate relative to each other about the center of rotation of the rotor core by an angle corresponding to the tooth width of the rotor teeth. As described above, by stacking the adjacent thin plates by rotating them in a certain direction at a certain angle, the number of rotor teeth formed on the rotor core can be set to two, and the frequency of the exciting current can be further reduced. Because of the configuration, in the variable reluctance type motor,
Iron loss such as hysteresis loss is significantly reduced, which makes it possible to prevent heat generation and improve efficiency.

[Brief description of drawings]

FIG. 1 is an end view of a stator core and a rotor core of a variable reluctance motor according to an exemplary embodiment of the present invention.

FIG. 2 is a front view of a laminated plate member forming a rotor core of the motor shown in FIG.

FIG. 3 is a plan view of a rotor of the motor shown in FIG.

FIG. 4 is an operation explanatory view of the motor of FIG.

FIG. 5 is an end view of a stator core and a rotor core of a conventional variable reluctance motor.

[Explanation of symbols]

 10 ... Motor housing 12 ... Stator core 14 ... Excitation winding 16 ... Rotor core 18 ... Output shaft 20 ... Stator teeth 22 ... Thin plate 24 ... Rotor teeth

Claims (3)

[Claims] 1. A motor housing, a substantially cylindrical stator core fixed to the inside of the motor housing, and having a plurality of stator teeth projecting radially inward at equal intervals on the inner circumference, and the stator core. A stator having a plurality of exciting windings wound around each of the stator teeth and capable of passing currents of different phases in a predetermined order, and sequentially forming magnetic poles at each of the stator teeth of the stator core; The magnetic poles are rotatably arranged in the stator core, and have a plurality of rotor teeth that are provided on the outer periphery at equal intervals and project outward in the radial direction, and the rotor teeth are sequentially formed on the stator teeth of the stator core. Variable reluctor including a rotor core that is attracted to and rotated by a rotor, and a rotor that is concentrically fixed to the rotor core and that has an output shaft that is rotatably supported by the motor housing. In the stator motor, the stator core has different excitation windings capable of passing at least three-phase currents around each of the stator teeth, so that at least six stator teeth having twice the number of phases are provided. The rotor core is formed by laminating and adhering a plurality of thin plates of a ferromagnetic material having a pair of the rotor teeth protruding outward in the radial direction at an axially symmetrical position on the outer circumference, and each thin plate is The pair of rotor teeth have an outer diameter dimension on the outer peripheral surface that is smaller than the inner diameter dimension of the inner peripheral surface of the stator tooth of the stator core, and the tooth width on the outer peripheral surface is the inner peripheral surface of the stator tooth. Is substantially equal to the tooth width of the rotor core, and each of the thin plates disposed at both ends in the axial direction of the rotor core has a center of rotation of the rotor core at a central angle corresponding to the tooth width of the rotor tooth. Each of the adjacent thin plates is laminated by being rotated relative to each other by a certain angle in a certain direction so as to be arranged to rotate around each other, and the stator is formed by stacking the pair of rotor teeth of each thin plate. A rotor 2 salient-pole variable reluctance motor having two magnetic poles of the rotor that are magnetically attracted to teeth. 2. The stator core includes six stator teeth, and each of the stator teeth has three sets of exciting windings capable of passing a three-phase current, with respect to the stator teeth in a radially symmetrical position. The rotor 2 salient-pole variable reluctance motor according to claim 1, wherein the rotor 2 salient-pole variable reluctance motor is wound so that currents of the same phase are supplied. 3. The plurality of thin plates forming the rotor core are formed such that each of the tooth widths on the outer peripheral surfaces of the pair of rotor teeth has a dimension corresponding to a central angle of 45 °. Rotor two salient pole type variable reluctance type motor described.