JP2015033245A - Rotor for permanent magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor for a permanent magnet rotor which reduces torque pulsation without deteriorating productivity and average torque.SOLUTION: A rotor for the permanent magnet motor is disclosed which reduces torque pulsation by providing a first rotor core 22, a second rotor core 23 and permanent magnets 14. In the first rotor core 22, permanent magnet insertion hole pieces 22a penetrating in a direction parallel with a rotation axis are disposed as many as the number of poles and on circumferential surfaces of magnetic poles between the permanent magnet insertion hole pieces 22a, a plurality of grooves 22b, 22c and 22d are provided which are disposed asymmetrically in the case where a virtual plane (f) passing through a d-axis and a rotation axis center is defined as a symmetry surface. The second rotor core 23 is formed by inverting front and rear sides of the first rotor core 22 in an axial direction, mutual permanent magnet insertion hole pieces 22a and 23a are located at the same positions in a circumferential direction, and the second rotor core 23 is stacked on the first rotor core 22 so as to form permanent magnet insertion holes 24, respectively, by communicating in a direction parallel with the rotation axis. The permanent magnets 14 are disposed in the permanent magnet insertion holes 24.

Description

  The present invention relates to a rotor of a permanent magnet motor.

  Conventionally, among permanent magnet type synchronous rotating electric machines (permanent magnet motors), in particular, embedded magnet type permanent magnet type synchronous rotating electric machines (hereinafter referred to as IPM motors) are widely known as representatives of small and high output motors. Yes. In this IPM motor, permanent magnets, mainly rare earth magnets, are inserted in order to pass magnetic fluxes that generate reluctance torque and magnet torque through the magnetic poles in the rotor.

  FIG. 4 is a schematic diagram for explaining a conventional IPM motor. FIG. 4A is a perspective view of a rotor included in the conventional IPM motor, and FIG. 4B is a front view of the conventional IPM motor. Respectively. In FIGS. 4A and 4B, an 8-pole IPM motor having 8 poles is shown as an example, and N and S in the figure represent N and S poles of a permanent magnet, respectively. ing. Moreover, as shown in the figure, generally, the d-axis passes through the center of the magnetic pole of the rotor core 11 between the permanent magnets 14 in the circumferential direction, and the q-axis is d In FIG. 4B, the permanent magnet and the rotor core are arranged at equal intervals in the circumferential direction.

  As shown in FIGS. 4A and 4B, the conventional IPM motor includes a stator core 10, a rotor 11, and a shaft 12.

  The stator core 10 is disposed on the outer periphery of the rotor 11 with a predetermined gap with respect to the rotor 11. The stator core 10 is provided with a stator winding (not shown).

  The rotor 11 includes a rotor core 13 and a permanent magnet 14, and is rotatable about a shaft 12 as a rotation axis.

  The rotor core 13 is formed by stacking hollow disk-shaped thin plates in the axial direction, and has permanent magnet insertion holes 13a that are rectangular holes corresponding to the number of poles (eight in this case). Yes.

  The permanent magnet 14 is a rectangular magnet that is magnetized in the circumferential direction of the rotor core 13 and is inserted into each of the permanent magnet insertion holes 13a.

  That is, in the conventional rotor 11, permanent magnet insertion holes 13a corresponding to at least the number of poles are arranged along the circumferential surface of the rotor core 13, and each rotor is inserted into each permanent magnet insertion hole 13a. A permanent magnet 14 magnetized in the circumferential direction of the core 13 is inserted.

  The permanent magnets 14 magnetized in the circumferential direction of the rotor core 13 are inserted into the permanent magnet insertion holes 13a that are radially arranged on a virtual straight line connecting the circumferential surface of the rotor core 13 and the rotation axis center. The inserted arrangement structure is called spoke arrangement.

Japanese Patent No. 4449035 JP 2011-83188 A JP 2004-173491 A

  In the rotor 11 in which the permanent magnets 14 are spoke-arranged as shown in FIGS. 4 (a) and 4 (b), the magnetic flux density in the gap between the adjacent permanent magnets 14 becomes a trapezoidal wave. In addition, there is a problem that torque pulsation is relatively large among various permanent magnet motors. This torque pulsation causes noise and vibration during operation of the permanent magnet motor.

  Therefore, in order to reduce the torque pulsation and the cogging torque, a measure for applying a skew to the stator core 10 or the rotor core 13 is generally employed.

  However, the above-described measures reduce the average torque at the same time as reducing the torque pulsation. Further, when the stator core 10 is skewed, it becomes difficult to automate the insertion of the stator winding, and when the rotor core 13 is skewed, it is difficult to insert the permanent magnet 14, or There arises a problem that the assembly process increases.

  Therefore, Patent Documents 1 to 3 propose methods for reducing torque pulsation without applying skew.

  In the above-mentioned Patent Document 1, in a rotor in which permanent magnets magnetized in the radial direction are arranged in the vicinity of the rotor core surface in a number corresponding to the number of poles, a circular arc or symmetric per pole on the surface of the rotor core A method of reducing a torque pulsation by providing a plurality of grooves has been proposed. However, this method does not describe a rotor in which a permanent magnet having a large torque pulsation is spoke-arranged, and when applied to a rotor in which a permanent magnet is spoke-arranged, due to the arc of the rotor core or a plurality of grooves, There is a problem that the q-axis magnetic flux is reduced and the reluctance torque acting on the rotor core is significantly reduced.

  In Patent Document 2, in the rotor substantially equivalent to Patent Document 1, grooves that are asymmetrically arranged per pole are provided on the outer side of the magnetic pole of the permanent magnet, and only the rotor core is inverted, and a plurality of them are arranged in the axial direction. A method for reducing torque pulsation by stacking is described. However, similarly to Patent Document 1, there is no description of a rotor in which permanent magnets are spoke-arranged, and it is necessary to provide a groove on the outer side in the circumferential direction of the magnetic pole of the permanent magnet. Not applicable to spoked rotors.

  Patent Document 3 describes a method of eliminating or reducing cogging torque by having a region in which the slot width is increased in the vicinity of the outer periphery of the magnet insertion slot of the rotor core in a rotor in which permanent magnets are spoke-arranged. ing. However, there is no description about torque pulsation when a current is passed through the stator winding. If the slot width is excessively increased, the q-axis magnetic flux decreases as in Patent Document 1, and the rotor core There is a problem that the working reluctance torque is greatly reduced.

  Accordingly, an object of the present invention is to provide a rotor of a permanent magnet motor that effectively reduces torque pulsation without deteriorating productivity and average torque.

The rotor of the permanent magnet motor according to the first invention for solving the above-mentioned problem is as follows.
A permanent magnet motor rotor in which permanent magnets magnetized in a circumferential direction are spoke-arranged along a circumferential surface,
Permanent magnet insertion hole pieces penetrating in a direction parallel to the rotation axis, at least corresponding to the number of poles, are arranged, and d-axis and circumferential surfaces of the magnetic poles between the permanent magnet insertion hole pieces A first rotor core provided with grooves that are asymmetrically arranged when a virtual plane passing through the rotation axis center is a symmetric plane;
The shape of the first rotor core is reversed in the axial direction, and the permanent magnet insertion hole pieces are in the same position in the circumferential direction and communicate with each other in a direction parallel to the rotation axis. A second rotor core stacked on the first rotor core so as to form permanent magnet insertion holes into which the permanent magnets can be embedded, respectively.
And the permanent magnets respectively disposed in the permanent magnet insertion holes.

The rotor of the permanent magnet motor according to the second invention for solving the above-described problems is as follows.
In the rotor of the permanent magnet motor according to the first invention,
One or more of the grooves are disposed only on one side in the circumferential direction from the virtual plane with respect to each of the magnetic poles.

  According to the rotor of the permanent magnet motor according to the first aspect of the present invention, the permanent magnet insertion hole pieces penetrating in the direction parallel to the rotation shaft are provided at least corresponding to the number of poles. A first rotor core provided with grooves which are arranged asymmetrically when a virtual plane passing through the d-axis and the rotation axis center is a symmetric surface on the circumferential surface of each magnetic pole between the pieces; The rotor core has a shape that is inverted in the axial direction, and each permanent magnet insertion hole piece is in the same position in the circumferential direction and communicates in a direction parallel to the rotation axis, so that the permanent magnet insertion hole The second rotor core stacked on the first rotor core and the permanent magnets respectively disposed in the respective permanent magnet insertion holes are deteriorated so that productivity and average torque are deteriorated. Without reducing torque pulsation effectively Kill.

  According to the rotor of the permanent magnet motor according to the second aspect of the present invention, since one or more of the grooves are disposed only on one side in the circumferential direction from the virtual plane with respect to each magnetic pole, Torque pulsation can be effectively reduced without deteriorating performance and average torque.

It is the schematic explaining the rotor of the IPM motor in Example 1 of this invention. (A) is a perspective view of the rotor of the IPM motor in Example 1 of this invention, (b) is a partial front view of a 1st rotor core, (c) is a 2nd rotor core. The front view of a part of is shown respectively. An electrical angle of 0 deg. Between the rotor of the IPM motor and the rotor of the conventional IPM motor in Example 1 of the present invention, calculated using magnetic field analysis by the finite element method. ~ 360 deg. It is a graph which shows the waveform of the torque in. The electrical angle between the rotor of the IPM motor and the rotor of the conventional IPM motor in Embodiment 1 of the present invention is 0 deg. ~ 360 deg. It is a graph which shows the peak torque of the average torque and torque amplitude in. It is the schematic explaining an example of the conventional IPM motor. (A) is the perspective view of the rotor of the conventional IPM motor, (b) represents the front view of the conventional IPM motor, respectively.

  Hereinafter, a rotor of a permanent magnet motor according to the present invention will be described with reference to the drawings by way of examples.

[Example 1]
FIG. 1 is a schematic diagram for explaining a rotor of an IPM motor in the present embodiment. FIG. 1A is a perspective view of a rotor of an IPM motor in the present embodiment, and FIG. A front view in which a part of the first rotor core is enlarged is shown, and FIG. 1 (c) is a front view in which a part of the second rotor core is enlarged. In the figure, as an example, an 8-pole IPM motor having 8 poles is shown, and N and S in the figure denote a permanent magnet N-pole and S-pole, respectively.

  As shown in FIGS. 1A, 1 </ b> B, and 1 </ b> C, the rotor 21 in this embodiment includes a first rotor core 22, a second rotor core 23, and a permanent magnet 14. Hereinafter, the description of the same components as those of the conventional IPM motor already described is partially omitted.

  As shown in FIGS. 1 (a) and 1 (b), the first rotor core 22 is obtained by laminating hollow disk-shaped thin plates in the axial direction so as to be about half the thickness of a conventional rotor core. In order to place the permanent magnets 14 in a spoke arrangement, the number of permanent magnet insertion hole pieces 22a, which are rectangular holes penetrating in a direction parallel to the rotation axis, corresponding to the number of poles (here, eight) are provided. The

  The first rotor core 22 is provided with a plurality of asymmetric grooves on the magnetic poles between the permanent magnet insertion hole pieces 22a on the circumferential surface. Here, the term “asymmetric” means that the virtual plane f passing through the d-axis and the rotation axis center is asymmetric when the plane is symmetrical. Furthermore, it is desirable that one or more grooves be disposed on one side in the circumferential direction from the virtual plane f with respect to each magnetic pole.

  As an example, FIGS. 1A and 1B show a state in which three of the first groove 22b, the second groove 22c, and the third groove 22d are disposed per pole. The d-axis is set to an electrical angle of 0 deg. The electrical angle is 25 deg. -70 deg. (In the case of an 8-pole IPM motor, three grooves 22b, 22c, and 22d are provided in a mechanical angle range of 6.25 deg. To 17.5 deg.).

  The second rotor core 23 has a shape obtained by inverting the first rotor core 22. That is, the permanent magnet insertion hole piece 23a of the second rotor core 23 shown in FIGS. 1A and 1C is the permanent magnet insertion hole piece 22a of the first rotor core 22 shown in FIGS. Similarly, the first groove 23b of the second rotor core 23 corresponds to the first groove 22b of the first rotor core 22, and the second groove 23c of the second rotor core 23 is the first groove The rotor core 22 corresponds to the second groove 22 c, and the second rotor core 23 of the third groove 23 d corresponds to the third groove 22 d of the first rotor core 22.

  Further, in the second rotor core 23, the respective permanent magnet insertion hole pieces 22a, 23a are in the same position in the circumferential direction with respect to the first rotor core 22, and in a direction parallel to the rotation axis. By communicating, permanent magnet insertion holes 24 are stacked so as to form each.

  The permanent magnet 14 is magnetized in the circumferential direction of the rotor 21 and is disposed in each permanent magnet insertion hole 24.

  Torque pulsation changes depending on the current flowing through the stator windings and the magnetic flux between the rotor and stator gaps due to the positional relationship between the rotor 21 and the slots of the stator core 10. By providing grooves (the above-mentioned grooves 22b, 22c, 22d or grooves 23b, 23c, 23d) on the surface of the rotor 21, it is equivalent to changing the distance between the gaps of the rotor and the stator. An effect is obtained. Enlarging the distance between the gaps is a very large resistance when viewed magnetically. Therefore, by appropriately selecting the position and number of grooves, it is possible to set the magnetic resistance between the gaps to a desired value and arbitrarily change the phase of torque pulsation.

  In the above description, at least one groove (the above-described grooves 22b, 22c, and 22d, or grooves 23b, 23c, and 23d) is disposed only on one side in the circumferential direction from the virtual plane f with respect to each magnetic pole. However, it is possible to prevent an increase in the magnetic resistance (due to the arrangement of the grooves) of the magnetic path through which the q-axis magnetic flux passes by arranging as described above. This is because a decrease in torque can be suppressed. Thereby, the reduction | decrease in reluctance torque can be suppressed to substantially half, and the reduction | decrease in average torque can be suppressed.

  In the present embodiment, the torque of the entire rotor 21 is a sum of the torque of the first rotor core 22 and the torque of the second rotor core 23. As described above, the reluctance torque is obtained by stacking the first rotor core 22 in which a plurality of grooves are provided only on one side in the circumferential direction from the virtual plane f and the second rotor core 23 in which the same structure is inverted. Can be reduced to almost half, and a decrease in average torque can be suppressed.

  In the present embodiment, as described above, in the first rotor core 22, the d-axis is set to an electrical angle of 0 deg. The electrical angle is 25 deg. -70 deg. (In the case of an 8-pole IPM motor, three grooves 22b, 22c, and 22d are provided in a mechanical angle range of 6.25 deg. To 17.5 deg.), And the second rotor core 23 is connected to the first rotor core 22. , The phase of the torque pulsation waveform acting on the first rotor core 22 and the second rotor core 23 is approximately 180 deg. The torque pulsation can be reversed and the torque pulsation of the entire rotor can be greatly reduced by canceling the torque pulsation by the first rotor core 22 and the second rotor core 23.

  In this embodiment, the average torque is not dropped, and the phase of torque pulsation between the first rotor core 22 and the second rotor core 23 is approximately 180 deg. An electrical angle of 25 deg. -70 deg. However, it is necessary to appropriately select the position and number of grooves according to the size and number of poles of the IPM motor and the magnetic characteristics of the permanent magnet.

  FIG. 2 shows an electrical angle of 0 deg. Between the rotor in the present example and the conventional rotor calculated using magnetic field analysis by the finite element method. ~ 360 deg. Is a graph showing the waveform of torque in the graph, with the horizontal axis representing the electrical angle and the vertical axis representing the torque (pu unit system). FIG. 3 shows an electrical angle of 0 deg. Between the rotor 21 in this embodiment and the conventional rotor 11. ~ 360 deg. Is a graph showing the peak to peak of the average torque and the torque amplitude, and the vertical axis represents the value of the peak to peak of the average torque and the torque amplitude (both in pu units).

  As shown in FIG. 2, torque pulsation appears remarkably in the conventional rotor 11 (see FIG. 4). On the other hand, in the rotor 21 (see FIG. 1) in this embodiment, the phase of the waveform of torque acting on the first rotor core 22 and the second rotor core 23 is approximately 180 deg. The torque pulsation is suppressed as the torque of the entire rotor obtained by adding the two torques.

  From the result of FIG. 2, as shown in FIG. 3, the torque pulsation (peak to peak) of the conventional rotor 11 is 0.37, whereas the torque pulsation (peak to peak) of the rotor 21 in this embodiment is shown. ) Is 0.08, and it can be seen that a reduction of 78.5% can be realized. On the other hand, the average torque of the conventional rotor 11 is 1.00, whereas the average torque of the rotor 21 in this embodiment is 0.99, which is a reduction of only 1%. Therefore, the rotor 21 in the present embodiment has high performance because it can reduce only the torque pulsation while suppressing the decrease in the average torque while using the permanent magnet as a spoke arrangement, as compared with the conventional rotor 11. It can be said.

  Further, even when the rotor 21 in this embodiment is compared with the case where the stator core 10 of the conventional rotor 11 is skewed, the decrease in the average torque is small, and the automatic insertion of the stator winding is easy. There is an advantage.

  Further, even if the rotor 21 in this embodiment is compared with the case where the rotor core 10 of the conventional rotor 11 is skewed, the decrease in average torque is small, and the permanent magnet insertion hole for inserting the permanent magnet 14 is used. Since 24 (permanent magnet insertion hole pieces 22a, 23a) are all oriented in the axial direction, there is an advantage that the permanent magnet 14 can be easily inserted.

  In the present embodiment, since the first rotor core 22 and the second rotor core 23 have the same structure, a mold for punching the first rotor core 22 and the second rotor core 23 is used. Only one type is required and productivity is good.

  In the above description, the first rotor core 22 and the second rotor core 23 are described as a single rotor. However, the first rotor core 22 and the second rotor core 23 are alternately arranged in a plurality of sets. The same effect can be obtained in the case of the constructed rotor.

  The rotor according to the first embodiment of the present invention has been described above. In other words, the rotor according to the first embodiment of the present invention includes a permanent magnet 14 magnetized in the circumferential direction and spokes along the circumferential surface. Permanent magnet insertion hole pieces 22a penetrating in the direction parallel to the rotation axis, the number corresponding to the number of poles, which are rotors of the permanent magnet motor arranged at least, are arranged. Is provided with grooves 22b, 22c, and 22d that are asymmetrical when a virtual plane f that passes through the d-axis and the rotation axis center is a symmetric surface. The shape of the core 22 and the first rotor core 22 are reversed in the axial direction, and the permanent magnet insertion hole pieces 22a and 23a are in the same position in the circumferential direction and in a direction parallel to the rotational axis. The permanent magnet 14 can be embedded by communicating The second rotor core 23 stacked on the first rotor core 22 so as to form the permanent magnet insertion holes 24, and the permanent magnets 14 disposed in the permanent magnet insertion holes 24, respectively. Is provided.

  As a result, the rotor according to the first embodiment of the present invention is a rotor of a permanent magnet motor in which permanent magnets having large torque pulsations are spoke-arranged, but the torque pulsations are reduced without deteriorating productivity and average torque. It can be effectively reduced.

  Further, in the rotor according to the first embodiment of the present invention, the grooves (the above-described grooves 22b, 22c, and 22d, or the grooves 23b, 23c, and 23d) have only one circumferential direction from the virtual plane f to each magnetic pole. One or more of them may be disposed on the screen.

  Thus, the rotor according to the first embodiment of the present invention is a rotor of a permanent magnet motor in which a permanent magnet having a large torque pulsation is spoke-arranged, and the torque can be reduced without deteriorating productivity and average torque. Pulsation can be effectively reduced.

  The present invention is suitable as a rotor of a permanent magnet motor.

DESCRIPTION OF SYMBOLS 10 Stator core 11 (Conventional) Rotor 12 Shaft 13 (Conventional) Rotor core 13a (Conventional) Permanent magnet insertion hole 14 Permanent magnet 21 (For the permanent magnet motor according to Embodiment 1 of the present invention) Rotor 22 First rotor core 22a Permanent magnet insertion hole piece 22b (for the first rotor core) First groove 22c (for the first rotor core) Second groove 22d (for the first rotor core) Third groove 23 of core (second rotor core 23a) Permanent magnet insertion hole 23b of second rotor core First groove 23c (of second rotor core) Second groove 23d (of second rotor core) 3rd groove 24 of 2nd rotor core Permanent magnet insertion hole

Claims (2)

A permanent magnet motor rotor in which permanent magnets magnetized in a circumferential direction are spoke-arranged along a circumferential surface,
Permanent magnet insertion hole pieces penetrating in a direction parallel to the rotation axis, at least corresponding to the number of poles, are arranged, and d-axis and circumferential surfaces of the magnetic poles between the permanent magnet insertion hole pieces A first rotor core provided with grooves that are asymmetrically arranged when a virtual plane passing through the rotation axis center is a symmetric plane;
The shape of the first rotor core is reversed in the axial direction, and the permanent magnet insertion hole pieces are in the same position in the circumferential direction and communicate with each other in a direction parallel to the rotation axis. A second rotor core stacked on the first rotor core so as to form permanent magnet insertion holes into which the permanent magnets can be embedded, respectively.
A permanent magnet motor rotor comprising: the permanent magnets disposed in the respective permanent magnet insertion holes.   2. The rotor of a permanent magnet motor according to claim 1, wherein at least one of the grooves is disposed on one side in a circumferential direction from the virtual plane with respect to each of the magnetic poles.

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