JP2017225218A - Rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a rotary electric machine that can reduce torque ripple against a wide range of torque.SOLUTION: In a rotary electric machine having a stator and a rotor (100), the rotor (100) has grooves (21a, 21b) formed on the outer peripheral surface, and deformation members (20a, 20b) are provided for deforming the shape of the grooves (21a, 21b) according to the generated torque (motor torque) of the rotary electric machine. The deformation members (20a, 20b) include a material having a lower rigidity than a rotor main body (110).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rotating electrical machine.

  As a background art of this technical field, the following Patent Document 1 describes a technique for reducing torque ripple by forming a groove on the outer peripheral surface of a motor rotor.

Japanese Patent No. 5516739

By the way, when a groove is formed in the motor rotor, the torque ripple reduction characteristic, that is, the range of motor torque that can significantly reduce the torque ripple, is determined by the shape (depth, width, cross-sectional shape, etc.) of the groove. The technique disclosed in Patent Literature 1 has a problem that the range of motor torque that can significantly reduce torque ripple is limited to a narrow range because the shape, width, depth, and the like of the groove are fixed.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a rotating electrical machine capable of reducing torque ripple with respect to a wide range of torque.

  In order to solve the above problems, the present invention provides a rotating electrical machine having a stator and a rotor, wherein the rotor has a groove formed on an outer peripheral surface thereof, and the shape of the groove is deformed according to the torque generated by the rotating electrical machine. It has the deformation member to be made, It is characterized by the above-mentioned.

Here, preferably, the rotor includes a rotor main body portion in which a concave portion is formed on an outer peripheral surface, and the deformable member embedded in the concave portion and formed with the groove, and the deformable member is the rotor main body. It is preferable to include a material having a lower rigidity than the portion.
When a low-rigidity material is used as the deformable member, the deformable member is easily deformed.

The deformable member may be deformed by a magnetic repulsive force against a magnetic field generated by the stator.
Thereby, the deformable member can be deformed according to the magnetic field generated by the stator.

  According to the present invention, torque ripple can be reduced for a wide range of torque.

It is a perspective view of the principal part of the rotor applied to the motor of a comparative example. It is a characteristic view of torque ripple. It is a perspective view of the principal part of the rotor applied to the motor of 1st Embodiment. It is a perspective view of the principal part of the rotor applied to the motor of 2nd Embodiment. (A) is sectional drawing of the principal part of the rotor applied to the motor of 3rd Embodiment, (b) is another sectional drawing of this rotor.

[Comparative example]
Before describing an embodiment of the present invention, a comparative motor will be described.
The motor of the comparative example has a stator and a rotor. Here, although not shown, the stator is configured in the same manner as a known motor stator. That is, the stator of this comparative example has a substantially cylindrical yoke, a plurality of teeth protruding inward from the inner peripheral surface of the yoke, and a winding wound around these teeth. When a three-phase alternating current is supplied to the winding, a rotating magnetic field is generated in the stator.

FIG. 1 is a perspective view of a main part of a rotor 10 applied to a motor of a comparative example.
The rotor 10 is configured in a substantially cylindrical shape as a whole. The motor of the comparative example is a 12-pole motor, and the rotor 10 has 12 magnetic poles. FIG. 1 shows one of the magnetic poles 12. In FIG. 1, substantially V-shaped grooves 14 a and 14 b are formed on the outer peripheral surface of the magnetic pole 12.

  A pair of magnet insertion portions 13, which are cavities having a substantially rectangular cross section, are formed inside the magnetic pole 12. A magnet (not shown) is inserted into each magnet insertion portion 13. For example, by slightly changing the shape in each of the 12 pole grooves, the flow of magnetic flux can be adjusted, and the torque ripple can be reduced as a whole motor. However, since the flow of magnetic flux generated in each part of the motor changes depending on the torque generated by the motor, that is, the magnitude of the motor torque, it is difficult to significantly reduce the torque ripple at any motor torque.

  FIG. 2 is a characteristic diagram showing the results of calculating torque ripples for three types of motors having different depths of the grooves 14a and 14b (hereinafter referred to as “groove depths”). Is the torque ripple. The characteristic L1 in the figure is a characteristic when the groove depth is 1 mm, the characteristic L2 is a characteristic when the groove depth is 2 mm, and the characteristic L3 is a characteristic when the groove depth is 3.5 mm. It is. According to the characteristics L1 and L2, when the groove depth is 1 to 2 mm, the torque ripple is relatively small in the region where the motor torque is relatively low, but the torque ripple is relatively large in the region where the motor torque is relatively high. . On the other hand, compared to the characteristics L1 and L2, the characteristic L3 has a relatively large torque ripple in a region where the motor torque is relatively low, and a relatively small torque ripple in a region where the motor torque is relatively high.

  Further, the characteristic LP shown in FIG. 2 is a characteristic when it is assumed that the groove depth becomes deeper in the range of 1 mm to 3.5 mm as the motor torque increases. According to this characteristic LP, torque ripple can be significantly suppressed within a wide range of motor torque. Each embodiment to be described later intends to control the groove depth so as to realize a characteristic as close to the characteristic LP as possible.

[First Embodiment]
Next, the motor (rotary electric machine) according to the first embodiment of the present invention will be described with reference to FIG. The motor of the present embodiment has a stator and a rotor 100, and FIG. 3 is a perspective view of the main part of the rotor 100. In FIG. 3, portions corresponding to the respective portions in FIG. 1 are denoted by the same reference numerals and description thereof may be omitted.
The motor of this embodiment is a 12-pole motor, and the rotor 100 is configured in a substantially cylindrical shape as a whole. The rotor 100 has twelve magnetic poles. FIG. 3 shows one of the magnetic poles 112. The rotor 100 includes a rotor main body 110 in which electromagnetic steel plates are laminated, and deformable members 20a and 20b. A pair of magnet insertion portions 13 is formed inside the magnetic pole 112 as in the comparative example (see FIG. 1), and a magnet (not shown) is inserted into each magnet insertion portion 13. In addition, recesses 15 a and 15 b that are cut out in a substantially trapezoidal shape are formed on the outer peripheral surface of the magnetic pole 112 of the rotor body 110.

  The deformable members 20a and 20b are fitted into the recesses 15a and 15b. However, in FIG. 3, the deformable member 20b is shown in a state of being removed from the groove 15b. The deformable members 20a and 20b are formed in a substantially trapezoidal shape in cross-section, but substantially V-shaped grooves 21a and 21b are formed on the outer peripheral surfaces exposed from the recesses 15a and 15b.

  A magnetic field is formed around the deformable members 20a and 20b by a stator (not shown). The magnetic field formed by the stator increases as the motor torque (see FIG. 2) increases. By the way, assuming that the motor of the present embodiment is applied to a vehicle such as an electric vehicle, noise and vibration due to torque ripple are likely to be a problem particularly during low-speed driving with low background noise. When driving at low speed, the motor tends to be driven in an orthogonal region without field-weakening control or the like, so the phase of the current magnetic field generated by the stator is constant, and the magnitude of the current magnetic field is considered to be proportional to the motor torque. be able to.

  The deformable members 20a and 20b are mainly composed of a giant magnetostrictive material. As the giant magnetostrictive material, for example, ETREMA Terfenol-D (registered trademark, composition is Tb: 0.27, Dy: 0.73, Fe: 1.9) may be adopted. As the giant magnetostrictive material, it is preferable to apply a material having lower rigidity than the electromagnetic steel sheet used for the rotor main body 110, and it is preferable to apply a material having a high magnetic permeability. The deformable members 20a and 20b are deformed so that the grooves 21a and 21b become deeper as the magnetic field increases. Further, as described above, when the magnitude of the current magnetic field is proportional to the motor torque, the grooves 21a and 21b become deeper as the motor torque increases.

  As described above, according to this embodiment, as the motor torque increases, the deformable members 20a and 20b are deformed so that the grooves 21a and 21b are deepened. Therefore, the characteristic of the generated torque ripple is the characteristic LP shown in FIG. Torque ripple can be reduced for a wide range of motor torque.

[Second Embodiment]
Next, a motor (rotary electric machine) according to a second embodiment of the present invention will be described with reference to FIG. The motor of this embodiment has a stator and a rotor 200, and FIG. 4 is a perspective view of the main part of the rotor 200. In FIG. 4, parts corresponding to those in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof may be omitted.
The motor of this embodiment is a 12-pole motor, and the rotor 200 is configured in a substantially cylindrical shape as a whole. The rotor 200 has 12 magnetic poles. FIG. 4 shows one of the magnetic poles 212. The rotor 200 includes a rotor main body 210 in which electromagnetic steel plates are laminated, and actuators 24a and 24b (deformable members).

  In the magnetic pole 212 shown in FIG. 4, grooves 14a and 14b are formed in the same manner as the magnetic pole 12 of the comparative example (see FIG. 1). Further, in the present embodiment, recesses 16a and 16b that are notched in a substantially rectangular parallelepiped are formed between the grooves 14a and 14b and the inner peripheral surface 210a inside the rotor body 210. The substantially rectangular parallelepiped actuators 24a and 24b are fitted into the recesses 16a and 16b. However, in FIG. 4, the actuator 24b is shown in a state where it is detached from the recess 16b.

  The control unit 30 is connected to the actuators 24a and 24b and controls the lengths of the actuators 24a and 24b in the longitudinal direction. For the actuators 24a and 24b, for example, piezoelectric elements having high magnetic permeability may be employed. In this case, the control unit 30 applies a voltage corresponding to the length in the longitudinal direction to be realized in the actuators 24a and 24b to the actuators 24a and 24b.

  The control unit 30 controls the actuators 24a and 24b such that the longer the motor torque, the shorter the length in the longitudinal direction. As a result, when the motor torque is small, the actuators 24a and 24b become longer, so the actuators 24a and 24b press the grooves 14a and 14b from the back side, and the grooves 14a and 14b become shallower. On the other hand, when the motor torque is large, the actuators 24a and 24b are shortened, so that the pressing force against the grooves 14a and 14b of the actuators 24a and 24b is weakened and the grooves 14a and 14b are deepened.

  As described above, according to the present embodiment, as the motor torque increases, the actuators 24a and 24b are deformed so that the grooves 14a and 14b become deeper. Therefore, the characteristics of the generated torque ripple are close to the characteristics LP shown in FIG. The torque ripple can be reduced for a wide range of motor torque.

[Third Embodiment]
Next, a motor (rotary electric machine) according to a third embodiment of the present invention will be described with reference to FIGS. The motor of this embodiment has a stator and a rotor 300, and FIGS. 5A and 5B are cross-sectional views of the main part of the rotor 300. However, FIG. 5A is a cross-sectional view when the magnetic field generated by the stator is Φ ₁ , and FIG. 5B is the same magnetic field Φ ₂ (where Φ ₁ <Φ ₂ ). FIG. 5A and 5B, parts corresponding to those in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof may be omitted.

  The motor of this embodiment is a 12-pole salient pole type motor, and the rotor 300 is configured in a substantially cylindrical shape as a whole. The rotor 300 has 12 magnetic poles. FIGS. 5A and 5B show one of the magnetic poles 312. The rotor 300 includes a rotor main body 310 in which electromagnetic steel plates are laminated and deformation members 26a and 26b. On the outer peripheral surface of the magnetic pole 312 of the rotor body 310, recesses 15a and 15b cut out in a substantially trapezoidal shape are formed. In addition, a magnet insertion portion 17 that is a cavity having a substantially V-shaped cross section is formed inside the magnetic pole 312, and a pair of magnets 18 a and 18 b are inserted into the magnet insertion portion 17. In addition, recesses 15 a and 15 b that are notched in a substantially trapezoidal shape are formed on the outer peripheral surface of the magnetic pole 312 of the rotor body 310.

  The deformable members 26a and 26b are fitted into the recesses 15a and 15b. The deformable members 26a and 26b are formed in a substantially trapezoidal cross section, but substantially V-shaped grooves 27a and 27b are formed on the outer peripheral surface exposed from the recesses 15a and 15b.

A magnetic field is formed around the deformable members 26a and 26b by a stator (not shown). The magnetic field formed by the stator increases as the motor torque (see FIG. 2) increases.
The deformation members 26a and 26b have a material that is deformed by a magnetic repulsive force against a magnetic field generated by the stator. Here, the deformable members 26a and 26b are preferably made of a magnetic material having a high magnetic permeability and a low rigidity. For example, electrical steel sheets with reduced carbon / silicon addition and reduced rigidity can be used as the deformable members 26a and 26b.

  Further, when the peripheral portions of the grooves 27a and 27b are formed in a leaf spring shape and elastically deformed by a magnetic repulsive force, a normal electromagnetic steel plate for a rotor yoke can be applied as it is as the deforming members 26a and 26b. is there. The deformation members 26a and 26b are deformed so that the grooves 27a and 27b become deeper as the magnetic field increases. As described above, when the magnitude of the current magnetic field is proportional to the motor torque, the grooves 27a and 27b become deeper as the motor torque increases.

  As described above, according to the present embodiment, the deforming members 26a and 26b are deformed by the magnetic repulsive force so that the grooves 27a and 27b are deepened as the motor torque is increased. The torque ripple can be reduced for a wide range of motor torque.

[Modification]
The present invention is not limited to the above-described embodiments, and various modifications can be made. The above-described embodiments are illustrated for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Further, it is possible to delete a part of the configuration of each embodiment, or to add or replace another configuration. Examples of possible modifications to the above embodiment are as follows.

(1) In each of the above embodiments, the groove depths of the grooves 21a, 21b, 14a, 14b, 27a, and 27b are changed by a magnetostrictive material, a piezoelectric element, a low-rigidity magnetic material, and the like. The groove depth may be changed using other means.

(2) Although various motors can be used as the motor applied to each of the above embodiments, the present invention can be applied to low-rotation motors such as in-wheel motors (motors incorporating motors in wheels). preferable. This is because the influence of deformation due to centrifugal force is reduced.

(3) It is preferable to apply a motor that positively utilizes reluctance torque, such as an embedded magnet type synchronous motor, to the motor applied to each of the above embodiments. In this type of motor, the electromagnetic force acting in the vicinity of the magnetic pole is mainly a repulsive force, so that the deformable members 20a, 20b, 26a, 26b and the like are easily deformed.

(4) In the above embodiments, the groove depths of the grooves 21a, 21b, 14a, 14b, 27a, 27b are changed. However, shapes other than the “groove depth” (for example, the groove width) , Cross-sectional shape, etc.) may be changed.

(5) Moreover, you may apply the motor of 1st-3rd embodiment not only to a vehicle but to various electric equipment.

14a, 14b, 21a, 21b, 27a, 27b Grooves 15a, 15b Recesses 20a, 20b, 26a, 26b
24a, 24b Actuator (deformable member)
100, 200, 300 Rotor 110, 210, 310 Rotor body

Claims (3)

In a rotating electrical machine having a stator and a rotor,
The rotor has grooves formed on the outer peripheral surface,
A rotating electrical machine comprising: a deforming member that deforms the shape of the groove according to a torque generated by the rotating electrical machine. The rotor includes a rotor main body portion having a recess formed on an outer peripheral surface, the deformation member embedded in the recess and forming the groove,
The rotating electrical machine according to claim 1, wherein the deformable member includes a material having lower rigidity than the rotor main body. The rotating electrical machine according to claim 2, wherein the deformable member is deformed by a magnetic repulsive force against a magnetic field generated by the stator.

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