JP3268951B2 - Variable reluctance motor - Google Patents

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.

[0002]

2. Description of the Related Art Conventionally, as one of variable reluctance motors, for example, as shown in FIG. 6, a stator S as a stator in which a coil C is wound around a plurality of magnetic pole projections ST provided on an inner peripheral portion, respectively. And a rotor R as a mover rotatably supported in a space surrounded by the stator S and having a plurality of magnetic pole projections RT on its outer periphery.

In this variable reluctance motor, as shown by a solid line in FIG.
When the coil C is energized when the magnetic pole protrusion RT of the rotor R is on the advanced side and the inductance of the coil C changes in the positive direction due to the rotation of the rotor R (increase region), the rotor R becomes positive. As shown by the dotted line in FIG. 6, the magnetic pole projection RT of the rotor R is on the retard side with respect to the magnetic pole projection ST of the stator S, and the rotation of the rotor R causes the inductance of the coil C to be negative. When the coil C is energized while the current is changing in the direction (reduction region), a negative rotational torque is generated in the rotor R.

[0004] As described above, the variable reluctance motor generates a positive or negative rotation torque by controlling the energization of the coil C at a predetermined rotor R position. The torque T is expressed by the following equation (1). Is done. T M = K · i ² · dL / dθ (1) where L: inductance of coil C, θ: phase angle of rotor R, i: current flowing through the coil, K: constant.

[0005]

By the way, in a variable reluctance motor having such a torque characteristic,
The torque applied to the rotor R and the displacement angle of the rotor R when the rotor R is gradually rotated with a constant current flowing for each phase to the coil C of the stator S constituting each phase of the motor. (I.e., the static torque for each phase) is as shown in FIG. That is, FIG. 7 shows that four magnetic pole protrusions RT are formed at equal intervals on the outer peripheral portion of the rotor R, and six magnetic pole protrusions ST are formed at equal intervals on the inner peripheral portion of the stator S. The torque characteristics for each phase of the three-phase motor in which the phases φ1 to φ3 are formed by the S-side magnetic pole projections ST are shown.
The static torque of each phase φ1 to φ3 sharply increases and decreases from around 0, and deviates greatly from the sine wave.

As a result, the output torque of the variable reluctance motor obtained by summing the static torques of the phases φ1 to φ3 has a considerably large pulsation. For example, the output torque of the variable reluctance motor is controlled by controlling the coil currents of the phases φ1 to φ3. , Each phase φ1 to φ3
However, since the torque of (1) greatly changes due to a small change in the coil current, there is a problem that the positioning accuracy at the time of stoppage is poor and also causes vibration.

On the other hand, increasing the number of phases or increasing the number of magnetic poles of the rotor R has been considered as a method of reducing the pulsation of the output torque. However, increasing the number of phases switches between energization and non-energization of each phase. There is a problem that it is necessary to increase the number of switching elements, which leads to an increase in cost. Increasing the number of magnetic poles of the rotor R requires high-speed ON / OFF control of the switching elements of each phase when the motor rotates at high speed. However, there is a problem that the switching frequency is increased and, consequently, heat is generated, and the rotation speed of the motor is limited. In other words, this method negates the greatest advantage of the variable reluctance motor, which is suitable for high-speed rotation because the variable reluctance motor has no magnet in the rotor.

The present invention has been made in view of these problems, and provides a variable reluctance motor that can realize high-speed driving of a motor without increasing costs and increasing heat generation, and that can improve positioning accuracy when stopped. The purpose is to do.

[0009]

According to a first aspect of the present invention, there is provided a stator having a plurality of magnetic pole projections, and a plurality of magnetic pole projections opposed to the magnetic pole projections of the stator. In the variable reluctance motor in which a coil is wound around each magnetic pole projection of the stator or the movable element, between the magnetic pole projections of the movable element, the adjacent magnetic pole projections A bridging portion extending toward the stator is provided, and small teeth are provided on a surface of each magnetic pole projection including the bridging portion facing the stator. Further, small teeth on the movable element side are provided on the magnetic pole projections of the stator. Characterized in that small teeth corresponding to are provided.

[0010] The invention described in claim 2 is the same as the claim 1.
In the variable reluctance motor described in the above, the mover is a rotor having a plurality of magnetic pole projections on the outer peripheral portion, the stator is disposed around the rotor, the coil is wound on the inner peripheral portion A stator having a plurality of magnetic pole projections,
The bridge portion is formed in a circumferential direction from each magnetic pole projection of the rotor to an adjacent magnetic pole projection.

According to a third aspect of the present invention, in the variable reluctance motor according to the first or second aspect, a rib for supporting the bridging portion is provided on the movable element. I do.

[0012]

In the variable reluctance motor according to the first aspect, each magnetic pole projection formed on the mover is provided with a bridging portion, and each magnetic pole projection including the bridging portion is connected to the stator. Small teeth are provided on the facing surface and the magnetic pole projections of the stator, respectively.

As a result, in the variable reluctance motor of the present invention, when the motor is driven at a low speed, the small teeth provided on the mover and the stator respectively act as magnetic pole projections, and the displacement of the mover accompanying the switching of the excitation phase. Becomes smaller. on the other hand,
At the time of high-speed driving, since the bridge portion is magnetically saturated, the small teeth do not function as magnetic pole projections, and the displacement of the mover accompanying the switching of the excitation phase increases.

Therefore, according to the variable reluctance motor of the present invention, when the motor is driven at a high speed, the movable element is largely displaced to secure its driving speed, and at a low speed drive, the movable element is finely divided (that is, at a high resolution). ) Displacement can improve the positioning accuracy. In other words, according to the present invention, conflicting requirements such as high-speed driving and improved positioning accuracy can be satisfied without increasing the number of motor phases or increasing the switching frequency during high-speed driving.

Next, a variable reluctance motor according to a second aspect is a rotary variable reluctance motor shown in FIG. 6 in which a stator is disposed around a rotor. In other words, the variable reluctance motor includes a linear motor in which a mover and a stator are formed in a flat plate shape and the mover slides in a plane direction along the stator, and a hollow rotor having a magnetic pole protrusion on an inner peripheral portion. A variable reluctance motor according to claim 2, wherein a so-called outer rotor type is known, comprising a stator disposed at a center position of the rotor and having a magnetic pole projection having a coil wound on an outer peripheral portion thereof. This is a general motor in which a rotor surrounded by a stator rotates. This type of variable reluctance motor normally rotates at a step angle θH represented by the following equation (2) by switching between energization and non-energization of each layer.

ΘH = 360 ° / m · NrH (2) where m is the number of stator phases, and NrH is the number of magnetic pole projections of the rotor. However, in the present invention, a bridge portion is formed on the rotor, and further, a magnetic pole projection on the rotor side including the bridge portion,
Since small teeth are formed on the stator-type magnetic pole projections, respectively, when the rotor is rotating at low speed, by switching between energizing and de-energizing each phase, the step angle θL expressed by the following equation (3) is obtained. The rotor can be rotated.

ΘL = 360 ° / m · NrL (3) where m is the number of stator phases, and NrL is the number of small teeth on the rotor side. That is, according to the variable reluctance motor of the present invention, the motor can be rotated at a high speed as in the conventional device, and the rotor can be driven at a high resolution at the above-mentioned step angle θL at the time of low-speed rotation. Therefore, the positioning accuracy when the motor is stopped can be improved without increasing the number of phases of the motor or increasing the switching frequency during high-speed rotation.

Next, in the variable reluctance motor according to the third aspect, the movable element is provided with a rib for supporting the bridge portion. Therefore, according to the present invention, the rib can reinforce the bridging portion against the force generated at the time of high-speed driving of the motor, and can prevent the bridging portion from being damaged at the time of high-speed driving.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing the internal configuration of the variable reluctance motor (three-phase) of the embodiment.

As shown in FIG. 1, a six-pole magnetic pole projection 14 (1) is provided on an inner peripheral portion of a cylindrical stator 10 made of a laminated iron core.
4a, 14b, 14c, 14a ', 14b', 14
c ') are provided at equal intervals. Of these six pole pole projections 14, a pair of pole pole projections 14a-
14a ', 14b-14b', and 14c-14c 'form the respective phases φ1, φ2, φ3 of the motor, and the magnetic pole projections 14a-14c' respectively correspond to the phases φ1-φ3. Annular coils 12a and 12
b, 12c are mounted. Also, four small teeth 15 at a predetermined pitch are provided on the inner peripheral portion of the tip of each magnetic pole projection 14.
Is provided.

On the other hand, in the cylindrical space surrounded by the stator 10, the output shaft 16 of the motor and the output shaft 1 are provided.
6 comprising a rotor core 18 supported by
Is rotatably supported. The rotor core 18 has four magnetic pole protrusions 22 (22a, 22b, 22a ',
22b '). A bridging portion 26 connecting the adjacent magnetic pole protrusions 22 is formed integrally with the outer peripheral portion of the tip of each magnetic pole protrusion 22 of the rotor 20. , NrL (for example, 40) small teeth 27 are formed at equal intervals.

The width t of the bridging portion 26 is set sufficiently smaller than the height y of the magnetic pole projection 22 as shown in FIG. The bridging portions 26 and the small teeth 27 can be easily formed by manufacturing the iron core forming plate 24 constituting the rotor 20 by punching such as a press.

The small teeth 27 of the rotor 20 and the small teeth 15 of the stator 10 can be opposed to each other, and their pitches are set to be substantially the same.
Each of the phases φ1 to φ3 is formed such that the phase shift is shifted by １ ／ of the pitch. That is, as shown in FIG. 1, the third phase (φ3) magnetic pole projections 14c and 14c
When the small teeth 15 formed on the c ′ face the small teeth 27 on the rotor 20 side, the magnetic pole projections 14 of the first phase (φ1)
a, 14a 'and the second phase (φ2) magnetic pole projections 14b,
The small teeth 15 formed on the small teeth 14b 'are small teeth 27 on the rotor side.
Is positioned on the advance or retard side by 1/3 of the pitch.

Although not shown, a rotary disk having a slit on the outer periphery is fixed to the output shaft 16 of the rotor 20, and the motor housing detects the slit in opposition to the rotary disk. A photo interrupter is provided.
That is, the variable reluctance motor of this embodiment is provided with a well-known rotational position detector including a rotating disk and a photo interrupter, and the position of the rotor 20 is determined based on a detection signal from the detector. It is supposed to be.

Next, the operation of the variable reluctance motor of this embodiment will be described. The variable reluctance motor according to the present embodiment is controlled in the same manner as the conventional device based on the principle described in the section of the related art. For example, during rotation driving, the magnetic pole projections 22a, 22a 'of the rotor 20 are connected to the first phase (φ1) magnetic pole projections 14a, 14a of the stator 10 side.
When approaching a '(the area where the inductance increases),
This state is detected by the rotational position detector, and based on this detection signal, an electronic control unit (not shown) outputs the first phase (φ
The power supply command to the coil 12a in 1) is output, and thereby a positive rotational torque is generated in the rotor 20. When the magnetic pole projections 22a and 22a 'of the rotor 20 move away from the magnetic pole projections 14a and 14a' of the stator 10 (in a region where the inductance is reduced), the current supply to the coil 12a is stopped and a negative rotation torque is generated. Instead, maintain the forward rotation torque. During braking, the magnetic pole projections 22a, 22a 'of the rotor 20 are connected to the magnetic pole projections 14a, 1a of the stator 10.
When moving away from 4a ', the coil 12a is energized to generate a braking force.

In driving the motor in this manner,
Since the width t of the bridging portion 26 of the rotor 20 is sufficiently smaller than the height y of the magnetic pole projection 22 of the rotor 20, the magnetic flux passing through the bridging portion 26 is magnetically saturated in a high magnetomotive force region rotating at a high speed, and the inductance is increased. Become smaller and are considered as grooves.

Accordingly, the static torque characteristic of the variable reluctance motor of this embodiment at the time of high speed rotation is substantially the same as that of the conventional device shown in FIG. 7, and the step angle θH at this time is as described above.
It can be obtained by equation (2). That is, in this embodiment, since m = 3 and NrH = 4 in the equation (2), the step angle θH at the time of high-speed rotation is 30 degrees.

On the other hand, when the rotor 20 is decelerated and stopped (that is, when the motor is rotating at a low speed), since the magnetomotive force is lower than that at the time of high speed rotation, the bridging portion 26 is not magnetically saturated and the effective magnetic path Becomes As a result, as shown in FIG. 2, the magnetic flux 30 tends to flow from the small teeth 15 formed inside the magnetic pole projections 14 to the small teeth 27 on the rotor 20 side, and the small teeth 15 on the stator 10 and the small teeth 15 on the rotor 20 side. The small teeth 27 respectively work as magnetic pole projections.

Accordingly, the static torque characteristic of the variable reluctance motor of this embodiment at the time of low speed rotation is as shown in FIG. 3, and the step angle θL at this time can be obtained by the above-mentioned equation (3). That is, in this embodiment, if NrL = 40 and m = 3 in the equation (3), the step angle θL at the time of low-speed rotation is equal to the step angle θL at the time of high-speed rotation.
1/10 of H, that is, 3 degrees.

That is, according to the variable reluctance motor of the present embodiment, the step angle θL at the time of stopping the rotor 20 is NrH / NrL compared with the step angle θH at the time of high-speed rotation.
Thus, the rotational position of the motor can be controlled with high resolution, so that the pulsation of the output torque of the motor and, consequently, the vibration can be suppressed, and the positioning accuracy when the motor stops can be improved.

When the variable reluctance motor of this embodiment is actually driven, as shown in FIG. 4, under operating conditions from start to acceleration operation, constant speed operation, and deceleration operation, pulsation of output torque is suppressed. In order to achieve high responsiveness and high-speed performance, drive in the high-speed rotation mode with a large step angle θH, and after the deceleration is completed, until the motor is stopped, in order to suppress the pulsation of the output torque and increase the stop accuracy, The operation may be performed in the positioning mode in which the step angle θL is small.

In order to realize such an operation pattern, the switching of the excitation phase may be performed at a step angle θH or θL according to the operation mode at that time.
The same circuit as the conventional device can be used as it is for the drive circuit for energization. That is, according to the variable reluctance motor of the present embodiment, high-speed rotation of the motor can be realized while securing the positioning accuracy at the time of stopping the motor, using the drive circuit conventionally used as it is.

Here, in this embodiment, the rotor 20
Although the description has been given assuming that the tip portions of the magnetic pole projections 22 on the side are simply joined by the bridging portion 26, for example, as shown in FIG. The narrow rib 28 may be connected to the rotor 20. In this case, the ribs 28 can reinforce the bridging portion 26 against centrifugal force at the time of high-speed rotation, and can prevent damage to the bridging portion 26 due to high-speed rotation.

The number of the small teeth 27 on the rotor 20 side has been described as, for example, forty. However, when setting the number of the small teeth 27, the setting which has been conventionally used when configuring a step motor is used. The method may be applied as it is. Also,
In the present embodiment, a three-phase variable reluctance motor having four magnetic pole protrusions 22 on the rotor 20 side has been described. However, the present invention is not limited to such a three-phase variable reluctance motor, but is conventionally realized as a variable reluctance motor. It goes without saying that the present invention can be applied to any type of variable reluctance motor (for example, four-phase or five-phase). The present invention is not limited to a rotary variable reluctance motor having a stator disposed around a rotor, but can be applied to any variable reluctance motor such as a linear motor and an outer rotor type motor.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an internal structure of a variable reluctance motor according to an embodiment.

FIG. 2 is an enlarged explanatory view showing an enlarged internal configuration of the variable reluctance motor of the embodiment.

FIG. 3 is a graph showing a static torque characteristic of the variable reluctance motor according to the embodiment at the time of low-speed rotation.

FIG. 4 is an explanatory diagram illustrating an example of an operation pattern of the variable reluctance motor according to the embodiment.

FIG. 5 is a diagram illustrating a modified example of the variable reluctance motor of the embodiment.

FIG. 6 is an explanatory diagram illustrating the principle of a variable reluctance motor.

FIG. 7 is a graph showing static torque characteristics of a conventional variable reluctance motor.

[Description of Signs] 10, S ... Stator 12 (12a to 12c), C ...
Coil 14 (14a to 14c '), ST: Magnetic pole projection (stator side) 15: Small teeth 20, R: Rotor 22 (22a to 22b'), RT
... Magnetic pole protrusion (rotor side) 26 ... Bridge part 27 ... Small teeth 28 ... Rib

Claims (3)

(57) [Claims] A stator having a plurality of magnetic pole projections; and a movable element having a plurality of magnetic pole projections opposed to the magnetic pole projections of the stator, wherein a coil is wound around each magnetic pole projection of the stator or the movable element. In the rotated variable reluctance motor, a bridge portion extending from each magnetic pole protrusion to an adjacent magnetic pole protrusion is provided between each magnetic pole protrusion of the mover, and the fixing of each magnetic pole protrusion including the bridge portion is provided. A variable reluctance motor, wherein small teeth are provided on a surface facing a stator, and small teeth corresponding to the small teeth on the mover side are provided on magnetic pole projections of the stator. 2. The rotor according to claim 1, wherein the mover is a rotor having a plurality of magnetic pole protrusions on an outer peripheral portion, and the stator is disposed around the rotor and has a plurality of magnetic poles wound around an inner peripheral portion. 2. The variable reluctance motor according to claim 1, wherein the stator is a stator having projections, and wherein the bridging portions are formed in a circumferential direction from each magnetic pole projection of the rotor to an adjacent magnetic pole projection. 3. 3. The variable reluctance motor according to claim 1, wherein a rib for supporting the bridging portion is provided on the mover.