JP6994199B2 - Permanent magnet rotor and rotating electric machine - Google Patents

Description

The present invention relates to a permanent magnet rotor and a rotating electric machine, and more particularly to a permanent magnet rotor in which a permanent magnet is embedded in a rotor core, and a rotating electric machine having such a permanent magnet rotor.

In a rotating electric machine using a permanent magnet rotor such as a permanent magnet embedded (IPM) motor, when manufacturing a rotor with a permanent magnet embedded in the rotor core, it is not attached rather than embedding a pre-magnetized permanent magnet in the rotor core. Magnetization is often performed with the permanent magnet material of magnetism embedded in the rotor core. At this time, it is necessary to sufficiently magnetize the entire permanent magnet material embedded in the rotor core.

For example, in Patent Document 1, the permanent magnet material is made anisotropic, the rotor (permanent magnet rotor) is rotatable and the axis is fixed to the center of rotation, and the rotor position is normal when magnetizing. Even if it deviates from the magnetized position of, the permanent magnet is magnetized in the normal direction, and the rotor position is returned to the regular magnetized position by the magnet torque, and as a result, the permanent magnet material can be completely magnetized. ing.

Japanese Unexamined Patent Publication No. 11-75350

Even if the magnetizing method as in Patent Document 1 is adopted, there is a difference in the positional relationship with the magnetizing coil in each part of the permanent magnet material having anisotropy, so that the applied magnetic field is not suitable. A uniform distribution occurs. Specifically, as shown in FIG. 5, it corresponds to the end of the magnetic pole far from the rotation center R of the rotor core 91 along the longitudinal direction of the slots 93, 94, 95 in which the permanent magnets 96, 97, 98 are embedded. At the position of the axis (referred to as the coil direction axis A), the magnetizing magnetic field H becomes stronger because it is close to the magnetizing coil 100, whereas the axis corresponding to the center of the magnetic pole near the rotation center R of the rotor core 91. At the position (referred to as the central axis B), since it is far from the magnetizing coil 100, the magnetizing magnetic field H becomes weak and it is difficult to achieve complete magnetization of the permanent magnet material. Even in such a position where the magnetizing magnetic field H is weak, it is necessary to use a magnetizing power source having a large capacity in order to achieve complete magnetization of the permanent magnet material.

In this type of rotor, as shown in FIG. 5, from the viewpoint of ensuring the mechanical strength of the rotor core 91 when centrifugal force is applied by the rotation of the rotor 90, the slots in which the permanent magnets 96, 97, 98 are embedded are embedded. 93, 94, 95 are often divided into two with the central axis B (rotor d-axis) in between. In this case, due to concerns about mechanical strength when the rotor 90 rotates at high speed, the position on the bridge 99 side in the center of the split portion, which is a position in the slots 93, 94, 95 where a large centrifugal force is difficult to be applied. In general, the permanent magnets 96, 97, and 98 are arranged close to each other. Then, a strong magnetizing magnetic field H cannot be efficiently applied to the positions where the permanent magnets 96, 97, and 98 are arranged, and a magnetizing power supply having a large capacity is used in order to achieve complete magnetizing. The need is especially high.

Further, in recent years, there is an increasing demand for rotating electric machines to be used at high temperatures and at high currents, and it is required to reduce the amount of heavy rare earth elements used in permanent magnets. Therefore, permanent magnets having a higher coercive magnetic force have come to be used because the crystal grains are finer than those of conventional permanent magnets such as hot-worked magnets. This type of hot-worked magnet with high coercive force requires a strong magnetic field for magnetism, and the higher the coercive force, the stronger the magnetic field required for magnetism.

An object to be solved by the present invention is to provide a permanent magnet rotor that easily magnetizes the entire area of a permanent magnet, and a rotating electric machine having such a permanent magnet rotor.

In order to solve the above problems, the permanent magnet rotor according to the present invention is a permanent magnet rotor having a rotor core and a permanent magnet embedded in a slot provided in the rotor core and forming a magnetic pole. In the cross section orthogonal to the center of rotation, the slot changes the distance from the center of rotation of the rotor core along the longitudinal direction, and the portion occupied by the permanent magnet is changed along the longitudinal direction of the slot. The outer magnet arrangement is provided at a position radially outer with respect to the rotation center of the rotor core than the portion not occupied by the permanent magnet.

Here, a plurality of the slots are arranged in layers in the radial direction of the rotor core, and among the plurality of slots arranged in layers, at least one of the slots other than the outermost slot of the rotor core. It is preferable that the permanent magnet is embedded in the outer magnet arrangement.

In this case, it is preferable that the permanent magnet is embedded in at least the innermost slot of the rotor core among the plurality of slots arranged in a layered manner in the outer magnet arrangement.

Then, the center of the rotor core when the shape of the slot in which the permanent magnet is embedded is approximated to an arc is compared with the center when the slot provided outside the rotor core is approximated to an arc. It should be located inside.

It is preferable that the permanent magnets are embedded in the outer arrangement at positions at both ends along the longitudinal direction of the slot.

In this case, when the shape of each of the permanent magnets embedded at the positions at both ends of the slot is approximated to an arc, the center thereof sandwiches a straight line along the radial direction of the rotor core passing through the center of the slot. It is recommended that they are separated from each other toward the opposite side of the permanent magnets provided.

The slots are located in two magnet-embedded slots located at both ends in the longitudinal direction in which the permanent magnets are embedded, and a flux barrier located between the two magnet-embedded slots in which the permanent magnets are not embedded. It should be divided.

In this case, it is preferable that the thickness of the flux barrier is larger than the thickness of the permanent magnets embedded in the magnet embedding slot that intersect in the longitudinal direction.

The rotary electric machine according to the present invention has the above-mentioned permanent magnet rotor.

In the permanent magnet rotor according to the above invention, the outer magnet arrangement is adopted, and the permanent magnet is embedded in the slot toward the position on the radial outer side of the rotor core. When magnetizing with the permanent magnet material embedded in the rotor core, the magnetizing magnetic field becomes stronger at the position outside the radial direction of the rotor core because it is closer to the magnetizing coil. Placing the permanent magnet material in such a position facilitates magnetization of the permanent magnet material and completes the entire area of the permanent magnet material without using an excessively large capacity as a magnetizing power source. Magnetization can be achieved.

Further, by arranging the permanent magnet at a position outside the radial direction of the rotor core, the magnetic resistance in the d-axis magnetic flux path is increased, and the relaxation torque generated in the rotor core is improved. As a result, the maximum output torque of the rotating electric machine under the same current constraint can be improved.

Here, a plurality of slots are arranged in layers in the radial direction of the rotor core, and among the plurality of slots arranged in layers, at least one of the slots other than the slot arranged on the outermost side of the rotor core has a permanent magnet. When embedded with an outer magnet arrangement, in such a layer arranged radially inside the rotor core, the distance from the magnetizing coil becomes long, and the magnetizing magnetic field passing through the magnet becomes large. By arranging the outer magnets of the permanent magnets, the effect of weakening the magnetizing magnetic field passing through the magnets can be slightly suppressed, and magnetization can be performed efficiently.

In this case, according to the configuration in which the permanent magnets are embedded in at least the innermost slot of the rotor core among the plurality of layers arranged in a layered manner in the outer magnet arrangement, the permanent magnet is embedded in the innermost part of the rotor core. At the position of the arranged slot, the magnetizing magnetic field is the weakest, but by adopting the outer magnet arrangement of the permanent magnets, the influence of the weakening of the magnetizing magnetic field can be slightly suppressed and the magnetizing efficiency can be improved.

Then, the center when the shape of the slot in which the permanent magnet is embedded is approximated to an arc is located inside the rotor core as compared with the center when the slot provided outside the slot is approximated to an arc. According to the configuration, the center when the shape of the slot in which the permanent magnet is embedded is approximated to an arc is more than the center when the slot of the layer outside the slot is approximated to the arc. , The entire area of the embedded permanent magnets tends to occupy a position radially outer with respect to the center of rotation of the rotor core. As a result, it becomes easy to magnetize the entire area of the embedded permanent magnet.

When the permanent magnets are embedded in the outer arrangement at both ends along the longitudinal direction of the slot, each of the permanent magnets arranged apart in the slot has the outer magnet arrangement. , It becomes easy to strengthen the magnetizing magnetic field.

In this case, the center of the permanent magnets embedded at both ends of the slot, when the shape of each permanent magnet is approximated to an arc, sandwiches a straight line along the radial direction of the rotor core passing through the center of the slot. According to the configuration in which the permanent magnets are separated from each other toward the opposite side to the provided side, each permanent magnet is relative to the rotation center of the rotor core as compared with the case where the center of each permanent magnet is on the above straight line. Therefore, it becomes easier to occupy the position on the outer side in the radial direction. As a result, it becomes easier to magnetize the entire area of the embedded permanent magnet.

Then, the slot is divided into two magnet-embedded slots located at both ends in the longitudinal direction in which the permanent magnet is embedded and a flux barrier located between the two magnet-embedded slots in which the permanent magnet is not embedded. In some cases, by providing a flux barrier, the position between the magnet-embedded slots located inside the rotor core in the radial direction and where the magnetizing magnetic field tends to be weak is effectively utilized to reduce the leakage of magnetic flux during magnetizing. In addition, it is possible to improve the relaxation torque generated in the permanent magnet rotor during the operation of the rotating electric machine in the state after magnetization.

In this case, according to the configuration in which the thickness of the flux barrier is larger than the thickness of the permanent magnets embedded in the magnet burial slot intersecting in the longitudinal direction, the effect of installing the flux barrier as described above becomes particularly large. ..

Since the rotary electric machine according to the above invention has the above-mentioned permanent magnet rotor, it is easy to magnetize the entire area of the permanent magnet embedded in the permanent magnet rotor, and it is not necessary to use a magnetizing power supply having an excessively large capacity. However, it is easy to achieve complete magnetization. In addition, a high reluctance torque can be obtained, and a high maximum output torque can be realized under the same current constraint.

It is sectional drawing which shows the structure of the permanent magnet rotor and the rotary electric machine which concerns on 1st Embodiment of this invention. It is an enlarged view which extracted a part of the cross-sectional view of FIG. It is a figure which shows the cross section of the permanent magnet rotor which concerns on the 2nd Embodiment of this invention. The second embodiment is an enlarged view showing the relationship between the arrangement of the magnet-embedded slots constituting the innermost layer slot and the position of the center. The permanent magnet is omitted from the display. It is a figure which shows the cross section of the conventional general permanent magnet rotor. It is a figure which shows the distribution of the principal stress in a rotor. Shows the case. It is a figure which shows the magnetizing magnetic field distribution in a rotor, (a) has an inner magnet arrangement, (b) has a thin flux barrier in the outer magnet arrangement, (c) has a thick flux barrier in the outer magnet arrangement. Shows the case. It is a figure which compares (a) the magnetizing magnetic field and (b) the current required for magnetizing for each structure of FIG. 7. It is a figure which shows the torque characteristic of a motor, (a) shows the inner magnet arrangement, (b) shows the outer magnet arrangement (without a flux barrier).

Hereinafter, the permanent magnet rotor and the rotating electric machine according to the first embodiment of the present invention will be described in detail with reference to the drawings.

[1] First Embodiment [Structure of a rotary electric machine]
The outline of the rotary electric machine 1 according to the first embodiment of the present invention is shown in FIG. 1 as a cross-sectional view orthogonal to the rotation center R. The rotary electric machine 1 has a permanent magnet rotor 10 according to an embodiment of the present invention. In this specification, the case where the rotary electric machine 1 is a motor will be mainly described, but the same configuration can be applied to the case where the rotary electric machine 1 is a generator.

The rotary electric machine 1 is configured as a permanent magnet embedded (IPM) motor. The motor 1 has a hollow cylindrical stator (stator) 30 and a rotor (permanent magnet rotor) 10 coaxially and axially rotatably supported in the hollow portion of the stator 30.

The stator 30 has a stator core 31 and a coil (not shown). The stator core 31 is formed by laminating a plurality of electromagnetic steel sheets, and integrally comprises an annular back yoke portion 31a and a plurality of teeth 31b protruding inward from the back yoke portion 31a. I have. A coil is wound around the outer circumference of each tooth 31b.

The rotor 10 has a rotor core 11 having a substantially columnar outer shape, and a plurality of permanent magnets 16, 17, 18 embedded in the rotor core 11. A hollow portion 12 through which the drive shaft 40 can be inserted is passed through the central portion of the rotor core 11. An air gap 50 is secured between the teeth 31b of the stator core 31 and the outer peripheral surface of the rotor core 11 in a state where the rotor 10 is coaxially housed in the hollow portion 12 of the stator 30. The details of the configuration of the rotor 10 will be described below.

[Outline of the configuration of the permanent magnet rotor]
As described above, the rotor (permanent magnet rotor) 10 has a rotor core 11 and permanent magnets 16, 17, and 18. The configuration of the rotor 10 is shown in FIGS. 1 and 2. FIG. 2 shows one magnetic pole of the rotor 10, and while alternately changing the polarities of the permanent magnets 16, 17, and 18 for each magnetic pole, a plurality of (here, eight) magnetic poles are continuously rotated symmetrically. The one arranged in a symmetrical manner is the entire structure of the rotor 10 as shown in FIG. In the following, terms indicating the direction of the rotating body, such as "circumferential direction", "inner circumference", "outer circumference", "diametrical direction", "outside", and "inside", refer to the direction of the rotor core 11 unless otherwise specified. do.

The rotor core 11 is configured by laminating a plurality of layers of electromagnetic steel sheets, and has a substantially cylindrical outer shape. The rotor core 11 is formed with slots 13, 14, 15 in which a permanent magnet can be embedded as a gap that is penetrated or depressed in the axial direction.

The slots 13, 14, and 15 have an arc shape that is convex toward the rotation center R side of the rotor core 11. The specific shapes of the slots 13, 14 and 15 are not particularly limited, but here, each has a substantially arc shape. That is, in the slots 13, 14, and 15, the inner peripheral edge located on the inner peripheral side of the rotor core 11 and the outer peripheral edge located on the outer peripheral side of the rotor core 11 are directed toward the inside of the rotor core 11, respectively. It is formed as a convex arc.

The number of layers of the slots is not particularly limited, but in the present embodiment, slots in which permanent magnets can be embedded are provided in multiple layers from the viewpoint of improving reluctance torque and the like. That is, the slots 13, 14, and 15 having a plurality of layers (here, three layers) are arranged so as to be separated from each other in the radial direction of the rotor core 11. In this embodiment, the three-layer slots 13, 14, and 15 are arranged in a concentric arc shape. The slots 13, 14, and 15 constituting the innermost layer, the intermediate layer, and the outermost layer have the central axis B (axis passing through the center of the magnetic pole; rotor d-axis) in the longitudinal direction intersecting the radial direction of the rotor core 11. It is divided into two parts by sandwiching it. The slots 13, 14, and 15 divided into two are adjacent to each other in the circumferential direction of the rotor core 11 via the bridge 19.

Permanent magnets 16, 17, and 18 are embedded in the three-layer slots 13, 14, and 15, respectively. Corresponding to the slots 13, 14, 15 having a substantially arc shape, the permanent magnets 16, 17, 18 also have a substantially arc shape. Further, corresponding to the fact that the slots 13, 14, and 15 are each divided into two, the permanent magnets 16, 17, and 18 of each layer are also divided into two, respectively.

Permanent magnets 16, 17, 18 occupy only a part of the area of slots 13, 14, 15 along the longitudinal direction of the arc shape of slots 13, 14, 15, as will be described in detail later. In the thickness direction connecting the outer peripheral side edge and the inner peripheral side edge of 13, 14 and 15, substantially the entire area of slots 13, 14 and 15 is occupied. Of the slots 13, 14, 15, the gaps 13a, 14a, 15a, which are areas not occupied by the permanent magnets 16, 17, 18 are the magnetic fluxes of the permanent magnets 16, 17, 18 and the leakage of the magnetic flux from the coil (rotor core). It plays a role of reducing the short circuit of the magnetic flux in 11.

The types of permanent magnets 16, 17, and 18 are not particularly limited, but are preferably metal magnets. Further, it is preferable that the magnet is a hot-worked magnet composed of microcrystal grains of a metal magnet material.

Further, in the rotor core 11, bridges 19 connecting between the inner peripheral side portions and the outer peripheral side portions of the slots 13, 14 and 15 are integrally formed with the rotor core 11 in various parts of the rotor core 11. In each bridge 19, when the rotor 10 is rotated about the axis, the outer peripheral side portion of the rotor core 11 is separated from the inner peripheral side portion by the action of centrifugal force, and each bridge 19 is permanently embedded in the slots 13, 14 and 15. It plays a role of preventing the magnets 16, 17, and 18 from scattering. In the present embodiment, each component of the rotor 10, including the slots 13, 14, 15 of each layer, the permanent magnets 16, 17, 18, and the bridge 19, is provided with respect to the central axis B along the radial direction of the rotor core 11. , Arranged symmetrically.

In the present embodiment, the effect of defining the arrangement of the permanent magnets 16, 17 and 18 in the slots 13, 14 and 15 makes it easier to magnetize the permanent magnet material in the rotor core 11. There is. In addition, the reluctance torque generated in the rotor 10 can be improved. Hereinafter, the arrangement of the permanent magnets 16, 17, and 18 and their effects will be described in detail with reference mainly to FIG. 2.

[Arrangement of permanent magnets]
In the rotor 10 according to the present embodiment, the permanent magnets 16, 17, 18 embedded in the slots 13, 14, 15 are partially arranged along the longitudinal direction of the arc shape of the slots 13, 14, 15. Occupies only the area.

Specifically, in the cross section orthogonal to the rotation center R of the rotor core 11, the portions occupied by the permanent magnets 16, 17, 18 along the longitudinal directions of the slots 13, 14, 15 are the permanent magnets 16, 17, The outer magnets are arranged at positions radially outer of the rotor core 11 with respect to the gaps 13a, 14a, and 15a not occupied by 18. Here, the position on the radial outer side of the rotor core 11 is a position where the distance from the rotation center R of the rotor core 11 is relatively long, and is separated from the central axis B along the arcuate shape of the slots 13, 14, and 15. , Refers to a position approaching the coil direction axis A. In other words, the position is on the air gap 50 side with the rotor 10 incorporated in the motor 1.

In the present embodiment, the permanent magnets 16, 17 and 18 are embedded in the positions of both ends of the slots 13, 14 and 15 along the longitudinal direction in an outer magnet arrangement. That is, in each of the slots 13, 14, and 15 divided into two, the permanent magnets 16, 17, and 18 are arranged toward the outermost positions along the longitudinal direction, and the permanent magnets 16, 17, and 18 are arranged. The gaps 13a, 14a, 15a are arranged at the inner positions along the longitudinal direction. The permanent magnets 16, 17 and 18 may be arranged outside the gaps 13a, 14a and 15a along the longitudinal direction of the slots 13, 14 and 15, and the slots 13, 14 and 18 do not necessarily have to be arranged outside. It does not have to be placed close to the outermost position in the longitudinal direction of 15. For example, a space having a certain length may be formed between the edges of the slots 13, 14, 15 outside the longitudinal direction (on the coil direction axis A side) and the permanent magnets 16, 17, 18. As such a space, for example, when the slots 13, 14 and 15 are formed in the rotor core 11, the space is caused by the R shape inevitably generated at the end of the slots 13, 14 and 15 due to the processing process. Can be mentioned. As such, even when a space is formed at a position outside the permanent magnets 16, 17, 18 along the longitudinal direction of the slots 13, 14, 15, the space is the permanent magnets 16, 17, 18 It does not matter as long as it is shorter in length along the longitudinal direction of the slots 13, 14, 15 than the gaps 13a, 14a, 15a provided inside.

As shown in FIG. 5, in the conventional general rotor 90 in which the slots 93, 94, 95 are divided into two, the permanent magnets 96,97 are arranged so as to be arranged radially inside the rotor core 91. Since it has been considered that the mechanical strength of the rotor core 91 at the time of high-speed rotation can be secured because the centrifugal force applied to the, 98 becomes small, the permanent magnets 96, 97, 98 are inserted into the slots 93, 94, 95. The inner magnets are arranged so as to be closer to the radial inside of the rotor core 91, that is, the central axis B side, along the longitudinal direction of the rotor core 91. In this case, when the permanent magnet material is embedded in the slots 93, 94, 95 and magnetized, the distance from the magnetizing coil 100 arranged outside the rotor core 91 along the coil direction axis A is long, and the center. At a position near the axis B, the magnetizing magnetic field H becomes weak. Since the permanent magnet material is arranged at a position where the magnetizing magnetic field H is weak, it is difficult to be magnetized, and a magnetizing power supply having a large capacity is required to achieve complete magnetization.

On the other hand, in the rotor 10 according to the present embodiment of FIGS. 1 and 2, the position of the central axis B where the outer magnet arrangement is adopted and the magnetic field H (not shown in FIG. 2) becomes weak in the permanent magnet material. Instead, it is located close to the magnetizing coil 100 (not shown in FIG. 2) and at a position on the coil direction axis A side where the magnetizing magnetic field H is strong. Therefore, it is easy to magnetize the permanent magnet material by using the strong magnetizing magnetic field H. It is possible to achieve complete magnetization without using a magnetizing power supply having such a large capacity.

In the rotor core 11, the magnetizing magnetic field H becomes weaker as the position hits the inner side in the radial direction. That is, among the slots 13, 14 and 15 of the three layers, the magnetic field H applied to the position on the central axis B side becomes weaker as the slot on the inner layer side. Therefore, the more the inner slot is, the greater the effect of improving the magnetizing efficiency by arranging the permanent magnets at the outer positions rather than the inner positions along the longitudinal direction can be obtained.

In particular, in the rotor 10 according to the present embodiment, a hot-worked magnet composed of microcrystalline particles of a metal magnet material is used as the permanent magnets 16, 17, and 18, and a strong magnetic field is required for complete magnetization. Will be. In a hot-worked magnet composed of fine crystal grains having a particle size of about 500 nm or less, in a non-magnetized state, a multimagnetic domain crystal grain in which a plurality of magnetic domains are formed across a magnetic wall and a single magnetic domain composed of a single magnetic domain. Although crystal grains are mixed, in order to completely magnetize the permanent magnets 16, 17 and 18, a high magnetic field is required in addition to the complete magnetization of the multi-domain crystal grains due to magnetic domain movement that occurs in a relatively low magnetic field. This is because it is necessary to achieve complete magnetization of the single magnetic domain crystal grains by the orientation of the easy axis of magnetism between the particles. Typically, the magnetic field required for complete magnetization is 20 kOe or more, and further, as the coercive force of the permanent magnets 16, 17, and 18 increases, the magnetic field required for complete magnetization also increases.

Even when a hot-worked magnet that is difficult to magnetize is used as described above, the permanent magnet 16 is located at an outer position along the longitudinal direction of the slots 13, 14, 15 provided in the rotor core 11 as in the present embodiment. By adopting the outer magnet arrangement in which, 17, and 18 are embedded, it becomes easy to perform complete magnetism. This type of hot-worked magnet can achieve a high coercive force by reducing the content of heavy rare earth elements compared to conventional general sintered magnets, reducing material costs and applying for large currents. It is suitable for application to motors that are expected to be used at high temperatures, and by making it possible to achieve complete magnetization without using a magnetizing power supply with an excessively large capacity, the material properties of these hot-worked magnets can be improved. It is possible to realize a fully utilized motor 1.

Further, in the rotor 10 according to the present embodiment, the outer magnet arrangement in which the permanent magnets 16, 17 and 18 are arranged at the outer positions along the longitudinal direction of the slots 13, 14 and 15 is adopted. The reluctance torque is improved in the motor 1 incorporating the rotor 10 as compared with the inner magnet arrangement in which the permanent magnets 96, 97, 98 are arranged in the inner position as in the conventional general form shown in FIG. Can be done. Since the gaps 13a, 14a, 15a are arranged at positions close to the central axis B (rotor d-axis) inside along the longitudinal direction of the slots 13, 14, 15, the magnetic resistance in the d-axis magnetic flux path. Is high. By improving the reluctance torque, the maximum output torque of the motor 1 under the same current constraint can be improved.

As described above, in general, the permanent magnets 96, 97, 98 have been configured to be arranged inside from the viewpoint of ensuring the mechanical strength of the rotor core 91, but as shown in later examples. There is no significant difference in the stress applied to the rotor core between the case where the permanent magnets are arranged outside and the case where the permanent magnets are arranged inside. Therefore, even if the outer magnet arrangement is adopted, it is possible to secure almost the same mechanical strength as the inner magnet arrangement. Even if the centrifugal force acting on the permanent magnet differs between the outer magnet arrangement and the inner magnet arrangement, the mechanical strength of the rotor core is not significantly affected by it.

In the present embodiment, the slots 13, 14, 15, and the permanent magnets 16, 17, and 18 have a substantially arc shape divided into two around the central axis B, but the specific shape is such. The distance from the rotation center R of the rotor core 11 to each part of the slots 13, 14 and 15 changes along the longitudinal direction of the slots 13, 14 and 15, and the distances of the slots 13, 14 and 15 are not limited to those of the rotor core 11. Among them, the portion occupied by the permanent magnets 16, 17, 18 is provided at a position radially outer with respect to the rotation center R of the rotor core 11 than the portion not occupied by the permanent magnets 16, 17, 18. Just do it. The presence or absence of division and the number of divisions are not limited. Further, in the present embodiment, the slots 13, 14, 15 of three layers are provided, and the permanent magnets 16, 17, 18 are embedded in the slots 13, 14, 15 of all three layers by the outer magnet arrangement. , The number of layers in all slots, and the selection of slots to embed permanent magnets in multiple layers so that the permanent magnets are embedded in at least one of the outermost layers other than the outermost layer. If so, it is not particularly limited. In this case, in the outermost layer, the permanent magnet may or may not be embedded, and the arrangement in the slot when it is embedded is not particularly limited.

Further, the specific dimensions of the slots 13, 14, 15 and the permanent magnets 16, 17, 18 may be arbitrarily set. For example, in the illustrated form, the thicknesses (dimensions between the outer peripheral side edge and the inner peripheral side edge) of the three layers of permanent magnets 16, 17, and 18 are almost the same in the three layers, but they are mutually. It may be different. In that case, the thicknesses of the permanent magnets 16, 17, and 18 of the innermost layer, the intermediate layer, and the outermost layer are L1, L2, and L3, respectively, and L1 ≧ L2 ≧ L3, more preferably L1> L2 ≧ L3, and L1> L2. > L3 is recommended. This makes it easier to avoid irreversible demagnetization of the permanent magnets 16, 17, and 18. Local magnetic flux concentration in the rotor core 11 may cause irreversible demagnetization of the permanent magnet, because such irreversible demagnetization is particularly likely to occur at the radial inner position of the rotor core 11.

[2] Second Embodiment Next, the rotor 10'according to the second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The rotor 10'according to the second embodiment can also form a rotary electric machine such as a motor, like the rotor 10 according to the first embodiment. Hereinafter, the parts having differences from the rotor 10 according to the first embodiment will be mainly described, and the configurations common to the rotor 10 according to the first embodiment are designated by the same reference numerals in the drawings. Moreover, the description is omitted.

In the rotor 10'according to the present embodiment, as shown in FIG. 3, the innermost layer slot 13'is divided into three regions of a pair of magnet-embedded slots 13b and a flux barrier 13c. A pair of magnet-embedded slots 13b are located at both ends of the innermost layer slot 13'in the longitudinal direction, and a flux barrier 13c is located between the magnet-embedded slots 13b.

Permanent magnets 16 divided into two are embedded in the magnet embedding slots 13b, respectively. In the illustrated embodiment, the permanent magnet 16 occupies the entire area of the magnet burying slot 13b and is embedded. However, when a gap is left in the magnet burying slot 13b, the permanent magnet 16 is used in each magnet burying slot 13b. It is preferably arranged at a position on the outer side in the longitudinal direction.

The flux barrier 13c is provided in the rotor core 11 as a gap penetrating or sinking in the axial direction, and is maintained as a gap. Alternatively, a non-magnetic material may be filled. The shape of the flux barrier 13c is not particularly limited, but in the present embodiment, it has a substantially arc shape and is arranged symmetrically with respect to the central axis B. The flux barrier 13c and the two magnet embedding slots 13b are adjacent to each other via the bridge 20.

Although the flux barrier 13c is not indispensable, by providing it, the leakage of magnetic flux when magnetizing the permanent magnet material is reduced, and the magnetizing magnetic field H is effectively applied to the permanent magnet material. It plays a role in making it so. Further, in the rotor 10'after magnetization, it is also effective in increasing the magnetic resistance of the d-axis magnetic flux path and improving the relaxation torque. As shown in FIG. 5, the position of the central portion in the longitudinal direction of the innermost layer slot 13'is a place where the magnetizing magnetic field H tends to be particularly weak, and even if the permanent magnet 16 is arranged, the magnetizing efficiency is poor. By providing a flux barrier 13c in various positions, a strong magnetic field H is applied to the permanent magnet material by arranging the outer magnet, and by installing the flux barrier 13c, magnetic flux leakage during magnetization is suppressed. As a result of both, the efficiency of magnetization can be effectively increased.

In the first embodiment, the flux barrier 13c in the present embodiment is provided inside the innermost layer slot 13 in the longitudinal direction with respect to the region occupied by the permanent magnet 16, and the gap portion 13a not occupied by the permanent magnet 16 is provided. Can be associated with. The gap portion 13a is partitioned from the portion where the permanent magnet 16 is embedded by the bridge 20, and the gap portions 13a on both sides of the central axis B are connected to one, which can be regarded as the flux barrier 13c.

The thickness of the flux barrier 13c is preferably larger than the thickness of the permanent magnet 16 in the innermost layer and the magnet embedding slot 13b. Here, the thickness of the flux barrier 13c, the permanent magnet 16, and the magnet embedding slot 13b is the distance between the outer peripheral side edge and the inner peripheral side edge of each, and intersects in the longitudinal direction of their arc shape. Directional dimensions. By increasing the thickness of the flux barrier 13c, as described above, the effect of suppressing the leakage of the magnetic flux at the time of magnetism and the effect of improving the reluctance torque in the state after magnetization are particularly enhanced. From the viewpoint of sufficiently enhancing these effects, the thickness of the flux barrier 13c is preferably 1.3 times or more the thickness of the magnet embedded slot 13b.

Further, in the rotor 10'according to the second embodiment of the present invention, as shown in FIG. 4 in which the portions of the slots 13', 14 and 15 are enlarged, the magnet-embedded slot 13b constituting the innermost layer slot 13' The arc-shaped centers c3a and c3b are located inward along the radial direction of the rotor core 11 with respect to the arc-shaped centers c1 of the intermediate layer slot 14 and the outermost layer slot 15 which are outer layers. The arcuate centers c3a and c3b of the pair of magnet-embedded slots 13b are in the radial direction of the rotor core 11 passing through the middle position of the pair of magnet-embedded slots 13b, that is, the center position of the innermost layer slot 13'. The magnet embedding slots 13b are separated from each other in the direction opposite to the direction in which the magnet embedding slots 13b are provided so as to sandwich the central axis B which is a straight line along the above. That is, the center c3a of the magnet embedded slot 13b on the left side of the central axis B is displaced to the right side of the central axis B, and the center c3b of the magnet embedded slot 13b on the right side of the central axis B is displaced to the left side of the central axis B. There is. The arc-shaped centers c3a and c3b of the two magnet-embedded slots 13b coincide with the arc-shaped centers of the permanent magnets 16 embedded in the centers c3a and c3b, respectively.

Assuming that the position of the center of the magnet-embedded slot 13b constituting the innermost layer slot 13'is the same as the position of the center c1 of the intermediate layer slot 14 and the outermost layer slot 15, as in the case of the first embodiment. The three-layer slots 13', 14, and 15 should be arranged in a concentric arc. The arrangement of the magnet-embedded slots 13b in the concentric innermost layer slots 13'is shown as the first arrangement P1 with hatching in FIG.

As shown by an arrow in FIG. 4, the center of the magnet-embedded slot 13b in the innermost layer is shifted inward in the radial direction from the position of the center c1 of the intermediate layer slot 14 and the outermost layer slot 15 to the center c2. Then, the longitudinal direction of the magnet embedded slot 13b is the longitudinal direction of the intermediate layer slot 14 and the outermost layer slot 15 as compared with the first arrangement P1 which coincides with the position of the center c1 of the intermediate layer slot 14 and the outermost layer slot 15. It stands at an angle that is closer to parallel to the central axis B than the direction. The arrangement of the magnet embedding slots 13b at this time is shown by a broken line in FIG. 4 as the second arrangement P2. At this time, the two magnet-embedded slots 13b are separated from each other with the central axis B in between, and approach each other toward the outer peripheral side of the rotor core 11. When the permanent magnets 16 are embedded in the magnet embedding slot 13b having the second arrangement P2, each permanent magnet 16 is located at a position radially outside the rotor core 11 (rotation center of the rotor core 11) as compared with the first arrangement P1. It will be placed at a position far from R).

Then, from the center c2 displaced inward in the radial direction along the central axis B with respect to the center c1, further, as shown by an arrow in FIG. 4, the center of each of the two magnet-embedded slots 13b is centered on the central axis B. Is shifted to both sides with the center c3a and c3b. At this time, if the position of the outer edge of each magnet-embedded slot 13b in the longitudinal direction is not changed, each magnet-embedded slot 13b stands at an angle closer to parallel to the central axis B (No. 1). Three arrangements P3). As a result, the permanent magnets 16 embedded in each magnet embedding slot 13b are increasingly arranged at positions outward in the radial direction of the rotor core 11.

In this way, by shifting the center position of the magnet embedding slot 13b in the innermost layer radially inward from the center positions of the intermediate layer slot 14 and the outermost layer slot 15 (center c1 → center c2), the magnet embedding slot The entire area of the permanent magnet 16 arranged in 13b approaches the magnetizing coil 100 used for magnetizing. As a result, it becomes easier to magnetize the entire area of the permanent magnet material in the innermost layer than in the case of the first arrangement P1. Then, by further shifting the center of the magnet-embedded slot 13b displaced inward in the radial direction to both sides with the central axis B sandwiched (center c2 → center c3a, c3b), the entire area of the permanent magnet 16 arranged in the magnet-embedded slot 13b. However, as it gets closer to the magnetizing coil 100, it becomes easier to magnetize the entire area of the permanent magnet material in the innermost layer.

Even when the magnet embedding slot 13b has a shape other than the arc shape, the center when the shape is approximated to the arc shape may be arranged as described above. Further, by configuring the magnet-embedded slot 13b constituting the innermost layer slot 13'so as to have the above-mentioned central arrangement, a particularly high effect can be obtained with respect to the improvement of magnetizing efficiency, but the effect is higher than that of the innermost layer. Similarly, the center of the slot constituting the outer layer, here the intermediate layer slot 14, is located radially inside the rotor core 11 as compared with the slot outside the slot, here the outermost layer slot 15. It may be configured as such. Further, the center of the slot divided into two may be shifted to both sides with the central axis B in between. With these configurations, the effect of improving the magnetizing efficiency can be obtained in the permanent magnets embedded in the slots of the layer.

Hereinafter, the present invention will be described in detail with reference to examples. Here, the effects on the mechanical strength, the distribution of the magnetized magnetic field, and the output torque due to the difference in the position of the permanent magnet in the slot were examined.

[1] Examination of mechanical strength First, the influence of the arrangement of permanent magnets in the slots on the mechanical strength of the rotor core was examined.

(analysis method)
The following three types of rotor models were prepared. The first model is of the conventional general form, in which the permanent magnets have an inner magnet arrangement and are arranged closer to the inner end of the slot in the longitudinal direction. Here, the slots have three layers, and permanent magnets are arranged in the inner magnet arrangement in all the slots including the outermost layer. No flux barrier is formed.

In the second model, as in the first embodiment of the present invention, the permanent magnets have an outer magnet arrangement and are arranged closer to the outer end of the slot in the longitudinal direction. Here, too, the slots are made up of three layers, and permanent magnets are arranged in the outer magnet arrangement in all the slots including the outermost layer. No flux barrier is formed.

In the third model, as in the second embodiment of the present invention, the outer magnet arrangement is adopted and the flux barrier is provided between the slots in the innermost layer. The thickness of the flux barrier is the same as that of the innermost layer slot. Here, too, the slots are made up of three layers, and permanent magnets are arranged in the outer magnet arrangement in all the slots including the outermost layer.

The distribution of stress applied to each part of the rotor by centrifugal force when the rotor of each of the above three models was rotated about the axis was analyzed. Table 1 summarizes the parameters used in the simulation.

(result)
FIG. 6 shows the distribution of the principal stress obtained by the simulation for each model. (A) is a first model with an inner magnet arrangement, (b) is a second model with an outer magnet arrangement and no flux barrier, and (c) is a third model with an outer magnet arrangement and no flux barrier. Shows.

Comparing the stress distributions in FIGS. 6 (a), (b) and (c), similar results were obtained in the form of the stress distribution and the magnitude of the stress applied to each position. There is. The maximum value of stress is also about the same. Moreover, in none of the models, the behavior of locally concentrating stress was not observed.

From this, it can be seen that the stress applied to the rotor core during rotor rotation is about the same regardless of whether the inner magnet arrangement or the outer magnet arrangement is adopted, and regardless of the presence or absence of the flux barrier. That is, even when the outer magnet arrangement is adopted, the same mechanical strength as in the case of the inner magnet arrangement can be secured in the rotor core.

[2] Comparison of magnetized magnetic field distribution Next, we analyzed how the magnetized magnetic field distribution changes depending on the arrangement of permanent magnets in the slots.

(analysis method)
The following three types of rotor models were prepared. First, the same model as the first model used in the above-mentioned examination of mechanical strength was adopted. That is, it has an inner magnet arrangement and does not have a flux barrier. The second model was the same as the third model used in the above study of mechanical strength. That is, in the outer magnet arrangement, between the innermost slots, there is a thin flux barrier with the same thickness as the innermost slots. Third, based on the second model above, the flux barrier was thickened and a new model was prepared. That is, the outer magnet arrangement has a thick flux barrier between the innermost slots.

Simulations were performed on the above three models to analyze the distribution of the magnetized magnetic field. The simulation was performed by electromagnetic field analysis using the finite element method (FEM). In the simulation, a magnetizing coil was placed on the outside of the rotor core at a position corresponding to the end of the magnetic pole, and the distribution of the magnetizing magnetic field generated in each part of the rotor was analyzed. The magnetomotive force was the same for the three models.

The parameters used in the simulation are as shown in Table 1 above. The distance from the center of rotation of the rotor core to the magnetizing coil was set to 86 mm at the innermost side of the magnetizing coil.

(result)
FIG. 7 shows the distribution of the magnetized magnetic field obtained by the simulation for each model. (A) shows the case where the inner magnet arrangement is adopted, (b) shows the case where the outer magnet arrangement has a thin flux barrier, and (c) shows the case where the outer magnet arrangement has a thick flux barrier. In FIG. 7, the strength of the magnetizing magnetic field is shown as a relative value, but the scales are the same for (a) to (c).

In FIG. 7, when the strength of the magnetizing magnetic field applied to the permanent magnet material of each layer embedded in each slot is compared, (a) the weakest in the case of the inner magnet arrangement, and (b) the thin flux in the outer magnet arrangement. When it has a barrier, it becomes stronger in the order of (c) having a thick flux barrier in the outer magnet arrangement. This tendency is the largest in the permanent magnet material embedded in the slot of the innermost layer, and (a) in the case of the inner magnet arrangement, the magnetizing magnetic field is generated in the inner part in the thickness direction of the permanent magnet material. The magnetizing magnetic field is significantly weaker than that of the permanent magnet material embedded in the outer portion in the thickness direction of the permanent magnet material and in the slots of the outer two layers. On the other hand, (b) when the outer magnet arrangement has a thin flux barrier, even in the inner part of the permanent magnet material embedded in the innermost layer slot in the thickness direction, except for the vicinity of the inner end in the longitudinal direction, the thickness direction A magnetizing magnetic field almost equivalent to that of the outer part is applied. Further, (c) when the outer magnet arrangement has a thick flux barrier, a strong magnetic field is applied almost uniformly to each part of the permanent magnet material embedded in the three-layer slot.

8 (a) shows a comparison of the minimum values of the magnetic field on the permanent magnet material in the magnetic field distribution of each model of FIGS. 7 (a) to 7 (c). Here, standardization is performed based on the value in the case of the inner magnet arrangement in (a), and the result is displayed. The symbols (a) to (c) in FIG. 8 correspond to those in FIG. 7.

In FIG. 8 (a), the difference in the magnitude of the magnetizing magnetic field seen in the comparison between the models in FIG. 7 is more clearly shown. By changing the arrangement of the inner magnets to the arrangement of the outer magnets and providing a flux barrier, the minimum value of the magnetizing magnetic field is improved by 5% or more. Further, by thickening the flux barrier in the outer magnet arrangement, the minimum value of the magnetizing magnetic field is improved by 25% or more as compared with the case of the inner magnet arrangement.

As shown in FIGS. 7A to 7C, the weaker the magnetizing magnetic field applied to each part of the permanent magnet material when magnetizing under the same conditions, the larger the current flowing through the magnetizing coil. Otherwise, complete magnetization cannot be achieved. The current required to achieve complete magnetization should be proportional to the reciprocal of the minimum value of the magnetic field applied when the magnetic field is applied under the same conditions. FIG. 8B shows the result of estimating the current required for magnetism in each model based on the result of FIG. 8A. Here, too, standardization is performed based on the value in the case of the inner magnet arrangement in (a), and the result is displayed.

According to FIG. 8B, the current required for magnetism can be smaller when the outer magnet is arranged and the flux barrier is provided than when the inner magnet is arranged. When the flux barrier is made thicker in the outer magnet arrangement, the required current amount is further reduced to 80% or less as compared with the case of the inner magnet arrangement.

From the above, it can be seen that by adopting the outer magnet arrangement, a stronger magnetizing magnetic field can be applied to the permanent magnet material than in the case of adopting the inner magnet arrangement. Then, by providing a thick flux barrier at a position between the slots corresponding to the center of the magnetic pole, the magnetizing magnetic field can be further strengthened. As a result, by adopting the outer magnet arrangement and further providing a thick flux barrier at the position between the slots, the current for achieving complete magnetism can be reduced, and the capacity of the magnetizing power supply can be reduced. It becomes possible to use a small one.

[3] Comparison of output torque Finally, we analyzed how the output torque of the motor changes depending on the arrangement of the permanent magnets in the slots.

(analysis method)
The following two types of rotor models were prepared. The first model is of the conventional general form, in which the permanent magnets have an inner magnet arrangement and are arranged closer to the inner end of the slot in the longitudinal direction. Here, the slots have three layers, but the permanent magnets are not arranged in the outermost slots, and the permanent magnets are arranged in the middle layer and the innermost layers in the inner magnet arrangement. No flux barrier is formed.

In the second model, as in the first embodiment of the present invention, the permanent magnets have an outer magnet arrangement and are arranged closer to the outer end in the longitudinal direction of the slot. Here, too, the slots have three layers, but the permanent magnets are not arranged in the outermost slots, and the permanent magnets are arranged in the intermediate layer and the innermost layers in the outer magnet arrangement. No flux barrier is formed.

Simulations were performed on the above two models to analyze the torque characteristics. The simulation was performed by electromagnetic field analysis using the finite element method (FEM). Here, the obtained magnet torque and reluctance torque were estimated by changing the current phase angle under the same current constraint that the amount of current applied to the motor (winding current 140 Arms) was the same.

The parameters used in the simulation are as shown in Table 1 above. The magnetic flux from the permanent magnets is almost equal in both models.

(result)
FIG. 9 shows the analysis results. (A) shows the result of the inner magnet arrangement, and (b) shows the result of the outer magnet arrangement.

Comparing (a) and (b) in FIG. 9, the magnet torque values are almost the same in both models. However, the reluctance torque value is different between the two models in the vicinity of the maximum value, and is larger in the outer magnet arrangement in (b). The total torque obtained as the total of the magnet torque and the reluctance torque is also different between the two models near the maximum value, reflecting the difference in the reluctance torque, and is larger in the outer magnet arrangement in (b). There is. Specifically, the maximum value of the total torque is 205.5 Nm in the inner magnet arrangement of (a) and 209.4 Nm in the outer magnet arrangement of (b).

As described above, it was shown that the reluctance torque is improved by adopting the outer magnet arrangement as compared with the case of adopting the inner magnet arrangement. As a result of the improvement in the reluctance torque, the maximum output torque of the motor under the same current constraint is also improved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

In the permanent magnet rotors 10, 10'according to the first embodiment and the second embodiment of the present invention, the permanent magnets 16, 17, 18 are placed in the slots 13, 14, 15 in the outer magnet arrangement. By arranging them, the effect of improving the magnetizing efficiency and the effect of improving the reluctance torque are obtained. Then, in the second embodiment, by providing the flux barrier 13c and arranging the centers c3a and c3b when the slot 13 is approximated to an arc shape at a predetermined position, the effect of improving the magnetizing efficiency and the reluctance The effect of improving torque is further enhanced. However, not only when the outer magnet arrangement is adopted, but also when the permanent magnets 16, 17 and 18 are arranged at arbitrary positions in the slots 13, 14, 15 as described above as the second embodiment. Similarly, by providing the flux barrier 13c and arranging the centers c3a and c3b when the slots 13, 14 and 15 are approximated to the arc shape at predetermined positions, the effect of improving the magnetizing efficiency and the reluctance The effect of improving the torque can be obtained.

1 Motor (rotary electric machine)
10,10'Rotor (Permanent Magnet Rotor)
11 Rotor core 12 Hollow part 13, 13'Innermost layer slot 13a Void part 13b Magnet embedded slot 13c Flux barrier 14 Intermediate layer slot 14a Void part 15 Outer layer slot 16 Outermost layer permanent magnet 17 Intermediate layer permanent magnet 18 Most Permanent magnets in the outer layer 19, 20 Bridge 30 Stator (stator)
50 Air gap 100 Magnetized coil c1 Center c2 of the slot of the middle layer and the outermost layer Center position c3a, c3b with the center c1 shifted inward in the radial direction Center A coil of the innermost layer slot with the center c2 shifted to both sides of the center axis B Directional axis B Central axis H Magnetized magnetic field R Rotation center P1 First arrangement P2 Second arrangement P3 Third arrangement

Claims (7)

In a permanent magnet rotor having a rotor core and a permanent magnet embedded in a slot provided in the rotor core and forming a magnetic pole.
In the cross section orthogonal to the center of rotation of the rotor core, the slot changes the distance from the center of rotation of the rotor core along the longitudinal direction.
The permanent magnet is located at both ends along the longitudinal direction of the slot, and the portion occupied by the permanent magnet is radially outside the center of rotation of the rotor core with respect to the portion not occupied by the permanent magnet. It is buried with the outer magnet arrangement provided at the position.
Each of the permanent magnets has an arc shape and has an arc shape.
The center of the arc shape sandwiches a straight line along the radial direction of the rotor core passing through the center of the slot, and the permanent magnet rotations are separated from each other toward the side opposite to the side where the permanent magnets are provided. Child. A plurality of the slots are arranged in layers in the radial direction of the rotor core, and among the plurality of slots arranged in layers, at least one of the plurality of slots other than the slot arranged on the outermost side of the rotor core is permanently arranged. The permanent magnet rotor according to claim 1, wherein the magnet is embedded in the outer magnet arrangement. The permanent magnet rotation according to claim 2, wherein the permanent magnet is embedded in at least the innermost slot of the rotor core among the plurality of slots arranged in a layered manner in the outer magnet arrangement. Child. The center when the shape of the slot in which the permanent magnet is embedded is approximated to an arc is located inside the rotor core as compared with the center when the slot provided outside the slot is approximated to an arc. The permanent magnet rotor according to claim 2 or 3 located. The slot has two magnet-embedded slots located at both ends in the longitudinal direction in which the permanent magnet is embedded, and an arc-shaped flux barrier located between the two magnet-embedded slots in which the permanent magnet is not embedded. The permanent magnet rotor according to any one of claims 1 to 4, which is divided into. The permanent magnet rotor according to claim 5 , wherein the thickness of the flux barrier is larger than the thickness of the permanent magnet embedded in the magnet-embedded slot so as to intersect in the longitudinal direction. A rotating electric machine having the permanent magnet rotor according to any one of claims 1 to 6 .

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