JP2010098931A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the control of a required inverter in a permanent magnet synchronous motor. <P>SOLUTION: The motor includes a cylindrical rotor in which a shaft is inserted at the center and which accommodates a plurality of permanent magnets annularly arranged with the shaft as a center, and a stator which is arranged so as to oppose the periphery of the rotor, and accommodates an armature winding for controlling the rotation of the rotor therein. In the motor, a direction in which a magnetic flux generated by the permanent magnet penetrates the rotor radially is set as a direct axis, and a direction which is the radial direction of the rotor and intersects with the direct axis is set as an orthogonal axis. The motor has a flux barrier 8 which reduces the inductance of the orthogonal axis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a cylindrical rotor in which a shaft is inserted at the center and a plurality of permanent magnets arranged annularly with the shaft as a center, and a rotor arranged opposite to the circumferential surface of the rotor. In particular, the present invention relates to a motor having a shaft that rotates at a high speed relative to a general-purpose motor.

In recent years, so-called hybrid automobiles equipped with a motor together with an engine have been put into practical use as automobiles in consideration of the global environment.
As a motor mounted on such a hybrid vehicle, a permanent magnet synchronous motor in which a permanent magnet is accommodated in a rotor as shown in Patent Documents 1 to 11 is used.

  On the other hand, a turbocharger rotates a turbine impeller using exhaust gas from an engine or the like and transmits the rotational drive to the impeller of the compressor to generate compressed air. Due to the fluctuation, torque shortage occurs, and compressed air may not be obtained stably. In view of this, a so-called electric supercharger has been proposed in which the above-described permanent magnet synchronous motor is used as a supercharger to compensate for the above torque shortage by the torque of the permanent magnet synchronous motor.

Japanese Patent No. 3811426 Japanese Patent No. 3819211 Japanese Patent No. 3596542 JP 2006-280195 A JP 2005-198487 A JP-A-2005-354798 JP 2005-328679 A JP 2003-324875 A Japanese Patent Laid-Open No. 2002-44888 JP 2000-350393 A JP 2001-258187 A

  However, the permanent magnet synchronous motor used for the electric supercharger is considerably higher than the permanent magnet synchronous motor mounted on the hybrid vehicle because the turbine impeller and the compressor impeller rotate at high speed. High speed rotation is required.

  The electric supercharger is equipped with an inverter for converting the DC power of the battery into AC power of an arbitrary frequency so that the rotation of the rotor can be controlled. There is a possibility that the drive frequency of the inverter becomes very high. In other words, when the shaft is rotated at a high speed, it is necessary to convert the DC power into a high frequency AC power in order to control the rotation of the rotor, and the drive frequency of the inverter becomes high, making control difficult. It is done.

In general, in a permanent magnet synchronous motor, so-called reluctance torque is effectively used to improve output. This reluctance torque is obtained when the direction in which the magnetic flux from the permanent magnet penetrates the rotor in the radial direction is a straight axis, and the radial direction of the rotor and the direction orthogonal to the direct axis is the orthogonal axis, the inductance of the straight axis and the orthogonal axis Torque generated by the difference from the inductance.
And when utilizing such a reluctance torque effectively, it is necessary to swing the drive frequency of an inverter according to rotation of a rotor, and control of an inverter becomes difficult.

  In such a permanent magnet synchronous motor that requires high-speed rotation, it becomes very difficult to control the inverter because the drive frequency becomes high and the drive frequency needs to be varied.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to facilitate control of a required inverter in a permanent magnet synchronous motor.

  The present invention adopts the following configuration as means for solving the above-described problems.

  According to a first aspect of the present invention, there is provided a cylindrical rotor having a shaft inserted through the center and containing a plurality of permanent magnets arranged in an annular shape with the shaft at the center, and a circumferential surface of the rotor. A stator that accommodates an armature winding for controlling the rotation of the rotor, and a direction in which the magnetic flux of the permanent magnet penetrates the rotor in the radial direction is a straight axis, and is a radial direction of the rotor. A motor having an orthogonal axis in a direction orthogonal to the straight axis and a flux barrier that reduces the inductance of the orthogonal axis is employed.

  According to a second invention, in the first invention, the flux barrier is a hole formed on the orthogonal axis.

  According to a third aspect, in the second aspect, the flux barrier is arranged closer to the center than the permanent magnet in the radial direction of the rotor.

  According to a fourth invention, in any one of the first to third inventions, the stator side is composed of a plurality of the permanent magnets arranged in a single or continuous manner in which the stator side is an S pole and the shaft side is an N pole. And the permanent magnet having the N side on the stator side and the S side on the shaft side, and is composed of all the permanent magnets except the permanent magnet constituting the first pole. The second electrode is provided with a second pole.

  According to a fifth invention, in the fourth invention, a plurality of the first poles and a plurality of the second poles are provided, and the first poles and the second poles are along a circumferential direction of the rotor. The configuration is characterized by being alternately arranged.

In the permanent magnet synchronous motor, the magnetic flux hardly passes in the perpendicular axis direction and the magnetic flux easily passes in the orthogonal axis direction, so that the inductance of the orthogonal axis is small and the inductance of the orthogonal axis is large.
On the other hand, according to the present invention, the inductance of the orthogonal axis is reduced by the flux barrier. Therefore, the difference between the inductance of the straight axis and the inductance of the orthogonal axis is reduced, resulting in a motor having a small reluctance torque.
Therefore, according to the present invention, the change rate of the drive frequency of the inverter accompanying the rotation of the rotor can be suppressed or eliminated, and control becomes easy.
Thus, according to the present invention, it is possible to easily control the required inverter in the permanent magnet synchronous motor.

It is sectional drawing which showed schematic structure of the motor which is one Embodiment of this invention. FIG. 6 is a cross-sectional view of a motor in which two first poles and two second poles 6 are alternately arranged along the circumferential direction of the rotor as a modification of the motor according to the embodiment of the present invention.

  Hereinafter, an embodiment of a motor according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a motor 100 of the present embodiment. In FIG. 1, the motor 100 is cut along a plane perpendicular to the extending direction of the shaft.
The motor 100 of this embodiment is a motor capable of high-speed rotation that can be suitably used particularly for an electric supercharger.
As shown in FIG. 1, the motor 100 of this embodiment includes a shaft 1, a rotor 2, and a stator 3.

The shaft 1 is a rod member that transmits the rotational power generated by the rotor 2 and the stator 3 to the outside, and is arranged extending in the direction perpendicular to the paper surface of FIG.
In addition, since the motor 100 according to the present embodiment is capable of high-speed rotation as described above, the rigidity of the shaft 1 is the shaft included in the motors disclosed in the above-described Patent Documents 1 to 11 cited as the prior art documents. It is desired that the rigidity is higher than the rigidity. And in the motor 100 of this embodiment, the rigidity of the shaft 1 is improved by making the diameter of the shaft 1 larger than the shaft with which the motor disclosed by patent documents 1-11 is equipped.
In addition, when the rigidity of the shaft 1 can be improved by suitably selecting the forming material and shape of the shaft 1, the diameter of the shaft 1 is the same as the diameter of the shaft included in the motor disclosed in Patent Documents 1 to 11. Alternatively, it can be set small.
Moreover, it is preferable that the forming material of the shaft 1 is formed of a non-magnetic material so that the magnetic lines of force of a permanent magnet included in the rotor 2 described later are directed toward the stator 3 efficiently. However, the shaft 1 can also be formed of a magnetic material.

  The rotor 2 and the stator 3 generate a rotational force by a magnetic field line caused by a magnetic field and a current flowing through an armature winding described later, and the stator 3 is fixed and the rotor 2 is rotated.

  The rotor 2 has a cylindrical shape through which the shaft 1 is inserted at the center, and includes a rotor core 4, a first pole 5, a second pole 6, and a flux barrier 7.

The rotor core 4 forms the outer shape of the rotor 2, and is formed into a cylindrical shape in which a hole for inserting the shaft 1 is formed in the central portion and is formed of a magnetic material.
In the rotor core 4, two spaces for accommodating a permanent magnet constituting the first pole 5 and a permanent magnet constituting the second pole 6, which will be described later, are arranged annularly with the shaft as the center. The permanent magnet is accommodated in the space.
That is, in the motor 100 of this embodiment, the rotor 2 accommodates therein a plurality of permanent magnets that are inserted in the center and arranged in an annular shape with the shaft 1 as the center.
The rotor core 4 may be formed, for example, by laminating a plurality of circular electromagnetic steel plates in the extending direction of the shaft 1 or by ferrite in order to suppress the generation of eddy currents on the surface. preferable.

  As shown in FIG. 1, the first pole 5 and the second pole 6 are accommodated by arranging a plurality (two in this embodiment) in an annular shape with the shaft 1 at the center inside the rotor core 4. The permanent magnet 10 is used. In addition, as the permanent magnet 10, a neodymium magnet can be used suitably, for example.

The motor 100 of this embodiment includes, as the permanent magnet 10, a first permanent magnet 11 having a stator side having an S pole and a shaft side having an N pole, and a stator side having an N pole and the shaft side having an S pole. A permanent magnet 12 is provided. The first permanent magnet 11 and the second permanent magnet 12 have a shape in which the stator side and the shaft side are curved along the peripheral surface of the rotor 2.
The first pole 5 is constituted by the first permanent magnet 11, and the second pole 6 is constituted by the second permanent magnet 12. That is, the first pole 5 is constituted by a single permanent magnet 10 (first permanent magnet 11) in which the stator side is the S pole and the shaft side is the N pole, and along the circumferential surface of the rotor 2. The stator side and the shaft side have a curved shape.
The second pole 6 is a permanent magnet 10 with the stator side set to N pole and the shaft side set to S pole, and all the permanent magnets 10 except for the permanent magnet 10 constituting the first pole 5 (that is, the first pole 6). 2 permanent magnets 12), and the stator side and the shaft side are curved along the circumferential surface of the rotor 2.

That is, the motor 100 according to the present embodiment is a so-called two-pole motor that includes only the first pole 5 and the second pole 6 as poles.
In the motor 100 of the present embodiment, the first pole 5 and the second pole 6 are installed in a range of 160 ° without overlapping when viewed from the radial direction of the rotor 2. It has a length substantially equal to the length of the rotor 2 in the direction (extending direction of the shaft 1).

The motor 100 according to the present embodiment includes a first flux barrier 8 (flux barrier in the present invention) provided on the orthogonal axis as the flux barrier 7, both end portions of the first pole 5, and the second pole 6. And a second flux barrier 9 provided so as to be in contact with both end portions.
In the present embodiment, the orthogonal axis is a radial direction of the rotor 2 (rotor core 4) and a direction orthogonal to the straight axis, as shown in FIG. The straight axis is a direction in which the magnetic flux generated by the permanent magnet 10 (the first pole 5 and the second pole 6) penetrates the rotor 2 (rotor core 4) in the radial direction.

The first flux barriers 8 are for reducing the inductance of the orthogonal axis, and two first flux barriers 8 are provided on the orthogonal axis so as to sandwich the shaft 1. Moreover, in the motor 100 of this embodiment, the 1st flux barrier 8 is arrange | positioned rather than the permanent magnet 10 at the center side (shaft 1 side) in the radial direction of the rotor 3 (rotor core 4).
The second flux barrier 9 suppresses leakage of magnetic flux from the stator 3 side to the shaft 1 side or from the shaft 1 side to the stator 3 side in the first pole 5 and the second pole 6.

The flux barrier 7 composed of the first flux barrier 8 and the second flux barrier 9 is composed of holes. However, the flux barrier 7 is not limited to the holes, and can be configured by a member having a low magnetic permeability.
When the first flux barrier 8 is provided on the stator 3 side in the case of a high-speed rotation motor such as the motor 100 of the present embodiment, durability against high-speed rotation of the rotor is reduced. For this reason, like the motor 100 of this embodiment, the 1st flux barrier 8 is arrange | positioned in the center side (shaft 1 side) rather than the permanent magnet 10 in the radial direction of the shaft 1 side, ie, the rotor 2 (rotor core 4). Is preferred.
Further, the first flux barrier 8 does not need to have a round shape as shown in FIG. 1, and may have a long hole shape, for example.

  The stator 3 is disposed opposite to the peripheral surface of the rotor 2 and accommodates an armature winding for controlling the rotation of the rotor 2 therein. A plurality of armature windings are provided at equal pitches in the circumferential direction of the rotor 2. The number of armature windings is set in consideration of the width of the first pole 5 and the second pole 6 in the circumferential direction of the rotor 2 and the like.

  Although not shown in FIG. 1, the motor 100 of this embodiment may include a casing that covers and supports the stator 3.

  In the motor 100 of this embodiment having such a configuration, the rotor 2 is driven to rotate by supplying AC power from an external DC power source to the armature winding in the stator 3 via an inverter. Power is taken out through the shaft 1.

According to the motor 100 of the present embodiment as described above, the inductance of the orthogonal axis is reduced by the first flux barrier 8. Therefore, the difference between the inductance of the straight axis and the inductance of the orthogonal axis is reduced, resulting in a motor having a small reluctance torque.
Therefore, the change rate of the drive frequency of the inverter accompanying the rotation of the rotor 2 can be suppressed or eliminated, and control becomes easy.
Thus, according to the motor 100 of the present embodiment, it is possible to easily control the required inverter in the permanent magnet synchronous motor.

Further, according to the motor 100 of the present embodiment, a configuration in which the first flux barrier 8 is a hole is adopted.
By adopting such a configuration, the magnetic permeability in the first flux barrier 8 is lowered, and the inductance of the orthogonal axis can be efficiently reduced. Therefore, the difference between the direct-axis inductance and the orthogonal-axis inductance can be effectively reduced.

Moreover, according to the motor 100 of the present embodiment, the first flux barrier 8 is arranged on the shaft 1 side, that is, on the center side (shaft 1 side) of the permanent magnet 10 in the radial direction of the rotor 2 (rotor core 4). Adopted.
By adopting such a configuration, it is possible to suppress a reduction in durability against the high-speed rotation of the rotor even when the motor is a high-speed rotation like the motor 100 of the present embodiment.

Further, according to the motor 100 of the present embodiment, the first pole 5 is constituted by a single permanent magnet 10 (first permanent magnet 11) in which the stator side is the S pole and the shaft side is the N pole. The second pole 6 is a permanent magnet 10 in which the stator side is an N pole and the shaft side is an S pole, and all the permanent magnets 10 except for the permanent magnet 10 constituting the first pole 5 (that is, the second permanent magnet 10). It is constituted by a magnet 12). That is, the motor 100 according to the present embodiment is a so-called two-pole motor that includes only the first pole 5 and the second pole 6 as poles.
The drive frequency of the inverter that supplies AC power to the armature winding of the stator 3 increases in proportion to the number of poles of the motor. Therefore, by setting the minimum number of poles as in the motor 100 of the present embodiment, the drive frequency of the inverter can be reduced, for example, with respect to a motor having four or more poles.
Therefore, according to the motor 100 of the present embodiment, in the permanent magnet synchronous motor, it is possible to reduce the drive frequency of the required inverter and to make control easier.

In addition, since the permanent magnet 10 (the first permanent magnet 11 and the second permanent magnet 12) included in the motor 100 of the present embodiment constitutes the first pole 5 and the second pole 6, in the circumferential direction of the rotor 2. It is installed in a range of 160 ° and has a length substantially equal to the length of the rotor 2 in the length direction of the rotor 2 (the extending direction of the shaft 1).
For this reason, when manufacturing the permanent magnet of such a magnitude | size, it is assumed that a yield is bad. Therefore, the permanent magnet 10 (the first permanent magnet 11 and the second permanent magnet 12) may be divided into two or three minutes in the circumferential direction of the rotor. That is, the first pole 5 and the second pole 6 are configured by arranging a plurality of small permanent magnets having a shape in which the stator side and the shaft side are curved along the circumferential surface of the rotor 2 in the circumferential direction of the rotor 2. You may make it do. Further, the permanent magnet 10 (the first permanent magnet 11 and the second permanent magnet 12) may be divided into two or three minutes in the length direction of the rotor (the extending direction of the shaft 1). That is, the first pole 5 and the second pole 6 are arranged by arranging a plurality of small permanent magnets having a shape in which the stator side and the shaft side are curved along the circumferential surface of the rotor 2 in the length direction of the rotor 2. You may make it comprise.
By adopting such a configuration, the size of each permanent magnet is reduced, the yield of the permanent magnet is improved, and even if it is damaged, only the damaged portion needs to be replaced. The motor 100 of this embodiment can be manufactured at a low price.
In the permanent magnet 10, only one of the first permanent magnet 11 and the second permanent magnet 12 may be divided in the circumferential direction of the rotor 2 or the length direction of the rotor 2.
Further, when the permanent magnet 10 is divided into a plurality of parts in the extending direction of the shaft 1, it is preferable that the divided permanent magnets are arranged so as to be shifted from each other in the circumferential direction of the rotor 2 to skew the rotor 2. . Thus, by skewing the rotor 2, for example, vibration and noise of the motor 100 can be reduced.

  Further, the first pole 5 and the second pole 6 may be configured by arranging a plurality of rod-shaped or half-moon shaped permanent magnets in the circumferential direction of the rotor.

  Furthermore, as shown in FIG. 2, by arranging two first poles 5 and two second poles 6 alternately along the circumferential direction of the rotor 2, the motor 100 has four poles. A permanent magnet synchronous motor may be used. That is, in the motor 100, the first pole 5 and the second pole 6 arranged on the rotor 2 are not limited to one each, and a plurality of the first pole 5 and the second pole 6 may be arranged. At this time, as the flux barrier 7, four first flux barriers 8 are provided on the central side (on the shaft 1 side) of the permanent magnet 10 on the orthogonal axis and in the radial direction of the rotor 2, and the first pole 5 and the second pole 2 are provided. A second flux barrier 9 is provided so as to be in contact with both ends of each of the poles 6.

As described above, in the motor 100, the rotational speed of the rotor 2 can be increased by increasing the number of poles by using the configuration shown in FIG. I can do it. Furthermore, in the motor 100, by providing the first flux barrier 8, the inductance of the orthogonal axis can be reduced. Thereby, in the motor 100, since the difference between the inductance of the straight axis and the inductance of the orthogonal axis becomes small, the reactance torque can be reduced.
By applying such a motor 100 as a power generator to a high-speed rotation generator with a turbo installed, a high-speed rotation generator capable of suppressing an increase in output voltage during high-speed rotation due to a reduction in reactance torque is realized. It becomes possible.

  The preferred embodiment of the motor according to the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the configuration in which the first flux barrier 8 is disposed on the center side of the permanent magnet 10 in the radial direction of the rotor 2 has been described.
However, the present invention is not limited to this, and a configuration in which the first flux barrier 8 is disposed outside the permanent magnet 10 in the radial direction of the rotor 2 may be employed.

Moreover, in the said embodiment, the structure whose 1st flux barrier 8 is a void | hole was demonstrated.
However, the present invention is not limited to this, and a notch that overlaps the orthogonal axis may be formed in the rotor core 4 and this notch may be used as the first flux barrier.

100... Motor 1. Shaft 2. Rotor 3. Stator 4. Rotor core 5 5. First pole 6 6. Second pole 7. Flux barrier 8. 1st flux barrier (flux barrier of the present invention), 9 ... 2nd flux barrier, 10 ... permanent magnet, 11 ... 1st permanent magnet, 12 ... 2nd permanent magnet

Claims (5)

A cylindrical rotor that houses a plurality of permanent magnets that are annularly arranged with the shaft at the center and a shaft inserted in the center, and is disposed opposite to the circumferential surface of the rotor and controls the rotation of the rotor And a stator that accommodates an armature winding for carrying out the operation, the direction in which the magnetic flux by the permanent magnet penetrates the rotor in the radial direction is a straight axis, and the radial direction of the rotor is orthogonal to the straight axis. A motor whose direction is an orthogonal axis,
A motor comprising a flux barrier for reducing the inductance of the orthogonal axis.   The motor according to claim 1, wherein the flux barrier is a hole formed on the orthogonal axis.   The motor according to claim 2, wherein the flux barrier is disposed more centrally than the permanent magnet in the radial direction of the rotor.   A first pole constituted by a plurality of the permanent magnets arranged in a single or continuous manner in which the stator side is an S pole and the shaft side is an N pole, and the stator side is an N pole and the shaft 4. The permanent magnet having a S pole on the side, and a second pole constituted by all the permanent magnets excluding the permanent magnet constituting the first pole. The motor in any one. A plurality of the first poles and a plurality of the second poles are provided, and the first poles and the second poles are alternately arranged along a circumferential direction of the rotor. Item 5. The motor according to Item 4.

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