JP2019187198A - Permanent magnet rotor and rotating electrical machine - Google Patents

Abstract

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 are provided. In a permanent magnet rotor having a rotor core and permanent magnets buried in slots provided in the rotor core and constituting magnetic poles, a rotation center of the rotor core is provided. In the cross section orthogonal to R, the slots 13, 14, 15 change their distance from the rotation center R of the rotor core 11 along the longitudinal direction, and the slots 13, 14, 15 become permanent along the longitudinal direction of the slots 13, 14, 15. The portions occupied by the magnets 16, 17, 18 are provided radially outward with respect to the rotation center R of the rotor core 11 from the portions 13a, 14a, 15a not occupied by the permanent magnets 16, 17, 18. , With an outer magnet arrangement. [Selection] Figure 2

Description

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

  In a rotary electric machine using a permanent magnet rotor, such as a permanent magnet embedded (IPM) motor, when a rotor having a permanent magnet embedded in a rotor core is manufactured, a permanent magnet that has been pre-magnetized is not attached to the rotor core. Magnetization is often performed with a magnetic permanent magnet material 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 and the rotor (permanent magnet rotor) is rotatable and the shaft center is fixed at the rotation center. Even if it is deviated from the magnetized position of the magnet, the permanent magnet is magnetized in the normal direction and the rotor position is returned to the normal magnetized position by the magnet torque, and as a result, the permanent magnet material can be completely magnetized. ing.

JP-A-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. 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 to be rotated (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 close to the rotation center R of the rotor core 91. At the position of (center 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 magnetized power source having a large capacity in order to achieve complete magnetization of the permanent magnet material.

  In this type of rotor, from the viewpoint of ensuring the mechanical strength of the rotor core 91 when a centrifugal force is applied by the rotation of the rotor 90, as shown in FIG. 93, 94, and 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 a high speed, a position on the bridge 99 side at the center of the divided portion, which is a position where a large centrifugal force is difficult to be applied in the slots 93, 94, 95. 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, 98 are disposed, and a magnetizing power source having a large capacity is used in order to achieve complete magnetization. The need is particularly high.

  In recent years, there has been a growing demand for rotating electric machines to be used at high temperatures and high currents, and there has been a demand for reducing the amount of heavy rare earth elements used in permanent magnets. Therefore, permanent magnets having a high coercive force and crystal grains are made finer than conventional permanent magnets such as hot-worked magnets. This type of high coercivity hot-working magnet requires a magnetic field that is strong against magnetization, and the higher the coercivity, the stronger the magnetic field required for magnetization.

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

  In order to solve the above problems, a permanent magnet rotor according to the present invention includes a rotor core and a permanent magnet rotor embedded in a slot provided in the rotor core and constituting a magnetic pole. In a cross section orthogonal to the rotation center, the slot has a distance from the rotation center of the rotor core that varies along the longitudinal direction, and a portion occupied by the permanent magnet along the longitudinal direction of the slot is: An outer magnet arrangement is provided that is provided at a position radially outside the rotational center of the rotor core with respect to 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 at least one of the plurality of slots arranged in layers other than the slots arranged on the outermost side of the rotor core. The permanent magnet may be embedded in the outer magnet arrangement.

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

  And, the center when the shape of the slot in which the permanent magnet is embedded approximates an arc is larger than the center when the slot provided outside the rotor core approximates the arc rather than the slot. It should be located inside.

  The permanent magnet may be embedded at the positions of both ends along the longitudinal direction of the slot with the outer arrangement.

  In this case, the center when the shape of each of the permanent magnets embedded in the positions of both ends of the slot is approximated to an arc is the straight line along the radial direction of the rotor core passing through the center of the slot, respectively. The permanent magnets may be separated from each other toward the opposite side.

  And, the slot includes two magnet burying slots located at both longitudinal ends where the permanent magnets are buried, and a flux barrier located between the two magnet burying slots and where the permanent magnets are not buried. It should be divided.

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

  A rotating electrical machine according to the present invention has the above-described permanent magnet rotor.

  In the permanent magnet rotor according to the present invention, the outer magnet arrangement is adopted, and the permanent magnet is embedded in the slot so as to approach the position on the radially outer side of the rotor core. When magnetization is performed in a state where the permanent magnet material is embedded in the rotor core, the magnetizing magnetic field is increased because the magnet is close to the magnetizing coil at a position radially outside the rotor core. By arranging the permanent magnet material in such a position, the permanent magnet material can be easily magnetized, and the permanent magnet material can be completely applied to the entire area without using an excessively large magnetizing power source. Magnetization can be achieved.

  Furthermore, by arranging a permanent magnet at a position radially outside the rotor core, the magnetic resistance in the d-axis magnetic flux path is increased, and the reluctance torque generated in the rotor core is improved. As a result, the maximum output torque of the rotating electrical 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 a permanent magnet is provided in at least one of the plurality of slots arranged in layers other than the slots arranged on the outermost side of the rotor core. In the case where the outer magnet is disposed and buried, the layer disposed on the inner side in the radial direction of the rotor core is far away from the magnetizing coil, and the magnetizing magnetic field passing through the magnet is greatly increased. On the other hand, when the permanent magnet has the outer magnet arrangement, the influence of weakening the magnetizing magnetic field passing through the magnet is slightly suppressed, and the magnetizing can be performed efficiently.

  In this case, according to the configuration in which the permanent magnet is embedded in the outermost magnet arrangement in at least the innermost slot of the rotor core among the plurality of slots arranged in layers, the innermost of the rotor core. Although the magnetizing magnetic field is weakest at the position of the arranged slot, the influence of the weakening of the magnetizing magnetic field can be suppressed slightly and the efficiency of magnetizing can be increased by adopting the outer magnet arrangement of the permanent magnet.

  The center when the shape of the slot in which the permanent magnet is embedded is approximated to an arc is positioned inside the rotor core compared to the center when the slot provided outside the rotor core is approximated to the arc rather than the slot. 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 the same as the center when the slot of the layer outside the slot is approximated to the arc. The entire area of the embedded permanent magnet tends to occupy a position radially outside the rotation center 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 positions of both ends along the longitudinal direction of the slot in an outer arrangement, each of the permanent magnets arranged separately in the slot takes the outer magnet arrangement. It becomes easy to strengthen the magnetizing magnetic field.

  In this case, the center of each permanent magnet embedded in the position of both ends of the slot approximates a circular arc, and the permanent magnet is sandwiched by 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, the respective permanent magnets are in relation to the rotation center of the rotor core as compared with the case where the centers of the permanent magnets are on the straight line. In addition, it becomes easier to occupy a position on the radially outer side. As a result, it becomes easier to magnetize the entire area of the embedded permanent magnet.

  The slot is divided into two magnet burying slots located at both ends in the longitudinal direction in which the permanent magnets are buried, and a flux barrier located between the two magnet burying slots and in which the permanent magnets are not buried. In this case, by providing a flux barrier, magnetic flux leakage during magnetization is reduced by effectively utilizing the position between the magnet embedded slots that are located on the inner side in the radial direction of the rotor core and the magnetization magnetic field tends to be weak. In addition, it is possible to improve the reluctance torque generated in the permanent magnet rotor during operation of the rotary 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 intersecting the longitudinal direction of the permanent magnet embedded in the magnet embedding slot, the effect by the above-described flux barrier is particularly increased. .

  Since the rotating electrical machine according to the invention has the permanent magnet rotor described above, it is easy to magnetize the entire area of the permanent magnet embedded in the permanent magnet rotor, and a magnetizing power source having an excessively large capacity is not used. However, it is easy to achieve complete magnetization. Further, a high reluctance torque can be obtained, and a high maximum output torque can be realized under the same current constraint.

It is a cross-sectional view which shows the structure of the permanent magnet rotor and rotary electric machine concerning 1st embodiment of this invention. It is the enlarged view which extracted a part of sectional drawing of FIG. It is a figure which shows the cross section of the permanent magnet rotor concerning 2nd embodiment of this invention. It is an enlarged view which shows the relationship between arrangement | positioning of the magnet embedding slot which comprises an innermost layer slot, and a center position about said 2nd embodiment. Permanent magnets are not shown. It is a figure which shows the cross section of the conventional general permanent magnet rotor. It is a figure which shows distribution of the main stress in a rotor, (a) is an inner magnet arrangement | positioning, (b) is an outer magnet arrangement | positioning and does not have a flux barrier, (c) has a flux barrier with an outer magnet arrangement | positioning. Shows the case. It is a figure which shows the magnetic field distribution in a rotor, (a) has an inner magnet arrangement, (b) has an outer magnet arrangement and a thin flux barrier, and (c) has an outer magnet arrangement and a thick flux barrier. Shows the case. FIG. 8 is a diagram comparing (a) a magnetizing magnetic field and (b) a current required for magnetization for each structure in FIG. 7. It is a figure which shows the torque characteristic of a motor, (a) is inner magnet arrangement | positioning, (b) has shown about outer magnet arrangement | positioning (no flux barrier).

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

[1] First embodiment [Configuration of rotating electric machine]
An 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 the present specification, a case where the rotating electric machine 1 is a motor will be mainly described, but the same configuration can be applied to a case where the rotating electric machine 1 is a generator.

  The rotating electrical machine 1 is configured as a permanent magnet embedded (IPM) motor. The motor 1 includes a hollow cylindrical stator (stator) 30 and a rotor (permanent magnet rotor) 10 that is coaxially supported in a hollow portion of the stator 30 so as to be axially rotatable.

  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 plates, and integrally includes an annular back yoke portion 31a and a plurality of teeth 31b protruding from the back yoke portion 31a toward the inside of the annular shape. I have. And the coil is wound around the outer periphery of each teeth 31b.

  The rotor 10 includes a rotor core 11 having a substantially cylindrical 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 31 b of the stator core 31 and the outer peripheral surface of the rotor core 11 in a state where the rotor 10 is accommodated coaxially in the hollow portion 12 of the stator 30. Details of the configuration of the rotor 10 will be described next.

[Outline of configuration of permanent magnet rotor]
As described above, the rotor (permanent magnet rotor) 10 includes the rotor core 11 and the permanent magnets 16, 17, and 18. The configuration of the rotor 10 is shown in FIGS. FIG. 2 shows one magnetic pole of the rotor 10, and a plurality of (here, eight) magnetic poles are continuously rotationally symmetrically while alternately changing the polarities of the permanent magnets 16, 17, and 18 for each magnetic pole. The overall arrangement of the rotor 10 is as shown in FIG. In the following, the terms indicating the direction in the rotating body, such as “circumferential direction”, “inner periphery”, “outer periphery”, “radial direction”, “outer side”, “inner side”, and the like refer to the direction with respect to the rotor core 11 unless otherwise specified. To do.

  The rotor core 11 is formed by laminating a plurality of layers of electromagnetic steel plates and has a substantially cylindrical outer shape. The rotor core 11 is formed with slots 13, 14, and 15 in which permanent magnets can be embedded as gaps penetrating or sinking in the axial direction.

  The slots 13, 14, 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 each of the slots 13, 14, and 15, the inner peripheral side edge located on the inner peripheral side of the rotor core 11 and the outer peripheral side edge located on the outer peripheral side of the rotor core 11 are respectively directed toward the inner side of the rotor core 11. It is formed as a convex arc.

  The number of slot layers is not particularly limited, but in the present embodiment, slots for embedding permanent magnets are provided in multiple layers from the viewpoint of improving reluctance torque. That is, in the radial direction of the rotor core 11, a plurality of layers (here, three layers) of slots 13, 14, 15 are arranged so as to be separated from each other. In this embodiment, the three layers of 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 a 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 on both sides. The slots 13, 14, 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 layers of slots 13, 14, and 15, respectively. Corresponding to the slots 13, 14, and 15 having a substantially arc shape, the permanent magnets 16, 17, and 18 also have a substantially arc shape. 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.

  The permanent magnets 16, 17, 18 occupy only a partial area of the slots 13, 14, 15 along the longitudinal direction of the arc shape of the 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, 15 occupies substantially the entire area of the slot 13, 14, 15. Of the slots 13, 14, 15, the gaps 13 a, 14 a, 15 a, which are regions not occupied by the permanent magnets 16, 17, 18, leak magnetic flux from the permanent magnets 16, 17, 18 and magnetic flux from the coil (rotor core). 11) to reduce the magnetic flux short circuit).

  Although the kind of permanent magnet 16, 17, 18 is not specifically limited, It is preferable that it is a metal magnet. Furthermore, it is preferable that it is a hot work magnet comprised from the microcrystal grain of the metal magnet material.

  Further, in the rotor core 11, bridges 19 that connect between the inner peripheral portion and the outer peripheral portion of each of the slots 13, 14, 15 are integrally formed with the rotor core 11 at various portions of the rotor core 11. When the rotor 10 is axially rotated, each bridge 19 separates the outer peripheral portion of the rotor core 11 from the inner peripheral portion by the action of centrifugal force, and is permanently embedded in the slots 13, 14, 15. It plays a role of preventing the magnets 16, 17, and 18 from scattering. In this 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 relative to the central axis B along the radial direction of the rotor core 11. Are arranged symmetrically.

  In the present embodiment, the effect of defining the arrangement of the permanent magnets 16, 17, 18 in the slots 13, 14, 15 is easy to perform magnetization in a state where the permanent magnet material is embedded in the rotor core 11. Yes. Further, the reluctance torque generated in the rotor 10 can be improved. Below, arrangement | positioning and the effect of the permanent magnets 16, 17, and 18 are demonstrated in detail, referring mainly to FIG.

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

  Specifically, in the cross section perpendicular to the rotation center R of the rotor core 11, the portions occupied by the permanent magnets 16, 17, 18 along the longitudinal direction of the slots 13, 14, 15 are permanent magnets 16, 17, An outer magnet arrangement is adopted, which is arranged at a position radially outside the rotor core 11 with respect to the gaps 13a, 14a, 15a not occupied by 18. Here, the position on the outer side in the radial direction of the rotor core 11 is a position where the distance from the rotation center R of the rotor core 11 is relatively far away from the central axis B along the arc shape of the slots 13, 14, 15. , Refers to a position approaching the coil direction axis A. In other words, the position is on the air gap 50 side in a state where the rotor 10 is incorporated in the motor 1.

  In the present embodiment, permanent magnets 16, 17, 18 are embedded in the positions of both ends along the longitudinal direction of each slot 13, 14, 15 with an outer magnet arrangement. That is, in each of the two divided slots 13, 14, 15, the permanent magnets 16, 17, 18 are arranged at the outermost position along the longitudinal direction. Also, gaps 13a, 14a, 15a are arranged at positions inside along the longitudinal direction. The permanent magnets 16, 17, and 18 need only be arranged outside the gaps 13 a, 14 a, and 15 a along the longitudinal direction of the slots 13, 14, and 15. It does not need to be arranged close to the outermost position in the longitudinal direction. For example, a space of a certain length may be formed between the end of the slots 13, 14, 15 on the outer side in the longitudinal direction (coil direction axis A side) and the permanent magnets 16, 17, 18. As such a space, for example, when the slots 13, 14, 15 are formed in the rotor core 11, those spaces that are inevitably generated at the ends of the slots 13, 14, 15 due to the machining process are used. Can be mentioned. As described above, 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 formed by the permanent magnets 16, 17, 18. As long as the length along the longitudinal direction of the slots 13, 14, 15 is shorter than the gaps 13 a, 14 a, 15 a provided on the inner side.

  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 disposed such that the permanent magnets are arranged radially inward of the rotor core 91. Since the centrifugal force applied to the rotor core 91 is considered to be able to ensure the mechanical strength of the rotor core 91 during high-speed rotation, the permanent magnets 96, 97, 98 have the slots 93, 94, 95. The inner magnet arrangement is arranged in the radial direction of the rotor core 91 along the longitudinal direction of the rotor core, that is, close to the central axis B side. 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 The magnetizing magnetic field H becomes weak at a position near the axis B. 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 source with a large capacity is required to achieve complete magnetizing.

  On the other hand, in the rotor 10 according to the present embodiment shown in FIGS. 1 and 2, the position of the central axis B where the outer magnet arrangement is taken and the permanent magnet material becomes weak in the magnetizing magnetic field H (not shown in FIG. 2). Instead, it is close to the magnetizing coil 100 (not shown in FIG. 2) and is disposed 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 using the strong magnetizing magnetic field H. Even without using a magnetizing power source with such a large capacity, complete magnetization can be achieved.

  In the rotor core 11, the magnetizing magnetic field H becomes weaker as the position hits the radially inner side. That is, of the three layers of slots 13, 14, and 15, the magnetization 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 effect of improving the magnetization efficiency by arranging the permanent magnets at the outer position, not the inner side, along the longitudinal direction is greatly obtained in the inner slot.

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

  Even when a hot-worked magnet that is difficult to be magnetized is used as described above, the permanent magnet 16 is disposed at an outer position along the longitudinal direction of the slots 13, 14, and 15 provided in the rotor core 11 as in the present embodiment. , 17 and 18 are arranged so that complete magnetization is easily performed. This kind of hot-working magnet can achieve a high coercive force by reducing the content of heavy rare earth elements compared to conventional sintered magnets, reducing material costs and using large currents. It is suitable for motors that are expected to be used at high temperatures and at high temperatures, and by making it possible to achieve complete magnetization without using an excessively large magnetizing power source, the material properties of these hot-worked magnets can be improved. A fully utilized motor 1 can be realized.

  Furthermore, in the rotor 10 according to the present embodiment, by adopting an outer magnet arrangement in which the permanent magnets 16, 17, 18 are arranged at outer positions along the longitudinal direction of the slots 13, 14, 15, 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 at the inner position as in the conventional general form shown in FIG. Can do. The gaps 13a, 14a, and 15a are arranged at positions on the inner side along the longitudinal direction of the slots 13, 14, and 15 and close to the central axis B (rotor d-axis). Because it becomes higher. By improving the reluctance torque, the maximum output torque of the motor 1 under the same current restriction can be improved.

  As described above, in general, the permanent magnets 96, 97, and 98 have been configured so as to be arranged on the inner side from the viewpoint of ensuring the mechanical strength of the rotor core 91, but as shown in the following examples. There is no great difference in the stress applied to the rotor core between the case where the permanent magnet is arranged outside and the case where the permanent magnet is arranged inside. Therefore, even if the outer magnet arrangement is adopted, it is possible to ensure 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 greatly affected thereby.

  In the present embodiment, the slots 13, 14, 15 and the permanent magnets 16, 17, 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, 15 changes along the longitudinal direction of the slots 13, 14, 15. Among them, the portion occupied by the permanent magnets 16, 17, 18 is provided at a position radially outside the rotational center R of the rotor core 11 with respect to the portion not occupied by the permanent magnets 16, 17, 18. Just do it. The presence / absence of division and the number of divisions are not limited. In the present embodiment, three layers of slots 13, 14, and 15 are provided, and permanent magnets 16, 17, and 18 are embedded in the slots 13, 14, and 15 of all three layers in the outer magnet arrangement. The number of layers of all slots, and the selection of the slot for embedding the permanent magnet among the slots of the plurality of layers, so that the permanent magnet is embedded in the outer magnet arrangement in at least one other than the outermost layer. If it does, it will not be limited in particular. In this case, in the outermost layer, the permanent magnet may or may not be embedded, and the arrangement in the slot when embedded is not particularly limited.

  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 of the three layers of permanent magnets 16, 17, 18 (dimensions between the outer peripheral side edge and the inner peripheral side edge) are substantially the same in the three layers, It may be different. In that case, the thicknesses of the innermost layer, intermediate layer, and outermost layer permanent magnets 16, 17, and 18 are respectively L1, L2, and L3, and L1 ≧ L2 ≧ L3, and more preferably L1> L2 ≧ L3 and L1> L2 > L3 is preferable. Thereby, it becomes easy to avoid irreversible demagnetization of the permanent magnets 16, 17 and 18. The irreversible demagnetization of the permanent magnet may occur due to local magnetic flux concentration in the rotor core 11, but such irreversible demagnetization is particularly likely to occur at a position radially inward of the rotor core 11.

[2] Second Embodiment Next, a rotor 10 ′ according to a second embodiment of the present invention will be described with reference to FIGS. Similarly to the rotor 10 according to the first embodiment, the rotor 10 ′ according to the second embodiment can also constitute a rotating electric machine such as a motor. Below, it demonstrates centering on the part which has a difference with the rotor 10 concerning said 1st embodiment, and about the structure which is common in the rotor 10 concerning 1st embodiment, attaches | subjects and shows the same code | symbol in a figure. A description thereof 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: a pair of magnet burying slots 13 b and a flux barrier 13 c. The pair of magnet embedding slots 13b are located at both longitudinal ends of the innermost layer slot 13 ', and the flux barrier 13c is located between the magnet embedding slots 13b.

  In the magnet embedding slot 13b, a permanent magnet 16 divided into two is embedded. In the illustrated form, the permanent magnet 16 occupies the entire area of the magnet embedding slot 13b. However, when a gap is left in the magnet embedding slot 13b, the permanent magnet 16 is connected to each magnet embedding slot 13b. It is preferable to arrange at a position outside 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 the gap. Alternatively, a nonmagnetic 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 13 c and the two magnet embedding slots 13 b are adjacent to each other through the bridge 20.

  The flux barrier 13c is not necessarily provided, but by providing it, 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. To play a role. Further, in the rotor 10 ′ after magnetization, it is effective in increasing the magnetic resistance of the d-axis magnetic flux path and improving the reluctance 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 disposed, the magnetizing efficiency is low. By using the various positions, the flux barrier 13c is provided, so that the strong magnetizing magnetic field H is applied to the permanent magnet material by taking the outer magnet arrangement, and the magnetic flux leakage during magnetization is suppressed by the installation of the flux barrier 13c. 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 in the inner side in the longitudinal direction of the innermost layer slot 13 with respect to the region occupied by the permanent magnet 16 and is not occupied by the permanent magnet 16. Can be associated. The gap 13a is defined by the portion where the permanent magnet 16 is embedded and the bridge 20, and the gap 13a on both sides of the central axis B is continuously connected to one to be regarded as the flux barrier 13c.

  The thickness of the flux barrier 13c is preferably larger than the thickness of the innermost permanent magnet 16 and the magnet embedding slot 13b. Here, the thicknesses of the flux barrier 13c, the permanent magnet 16, and the magnet embedding slot 13b are distances between the outer peripheral side edge and the inner peripheral side edge, and intersect the longitudinal direction of the arc shape thereof. Dimension in the direction. By increasing the thickness of the flux barrier 13c, as described above, the effect of suppressing leakage of magnetic flux during magnetization and the effect of improving the reluctance torque in a 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 embedding slot 13b.

  Furthermore, 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 ′ is provided. The arc-shaped centers c3a and c3b are located on the inner side in 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 arc-shaped centers c3a and c3b of the pair of magnet buried slots 13b are in the radial direction of the rotor core 11 passing through the middle position of the pair of magnet buried slots 13b, that is, the center position of the innermost layer slot 13 ′. Are spaced apart from each other in a direction opposite to the direction in which the respective magnet embedding slots 13b are provided, with the central axis B being a straight line extending along the axis. That is, the center c3a of the magnet buried slot 13b on the left side of the central axis B is shifted to the right side of the central axis B, and the center c3b of the magnet buried slot 13b on the right side of the central axis B is shifted to the left side of the central axis B. Yes. The arc-shaped centers c3a and c3b of the two magnet embedding slots 13b coincide with the arc-shaped centers of the permanent magnets 16 embedded therein.

  If the position of the center of the magnet buried slot 13b constituting the innermost layer slot 13 ′ coincides with 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 layers of slots 13 ', 14, and 15 should be arranged in a concentric arc shape. The arrangement of the magnet embedding slots 13b in the concentric innermost layer slot 13 'is shown as hatched in FIG. 4 as the first arrangement P1.

  As shown by the arrows in FIG. 4, the center of the innermost magnet buried slot 13b is shifted from the position of the center c1 of the intermediate layer slot 14 and the outermost layer slot 15 to the inner side in the radial direction of the rotor core 11, and the center c2 Then, compared with the first arrangement P1 that coincides with the position of the center c1 of the intermediate layer slot 14 and the outermost layer slot 15, the longitudinal direction of the magnet embedding slot 13b is the longitudinal direction of the intermediate layer slot 14 and the outermost layer slot 15. It becomes a standing state at an angle approaching parallel to the central axis B rather than the direction. The arrangement of the magnet embedding slots 13b at this time is indicated 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 across the central axis B and approach the outer peripheral side of the rotor core 11, respectively. When the permanent magnets 16 are embedded in the magnet embedding slots 13b in the second arrangement P2, the permanent magnets 16 are positioned on the radially outer side of the rotor core 11 (the rotation center of the rotor core 11) than in the first arrangement P1. (Position far from R).

Then, from the center c2 shifted radially inward along the central axis B with respect to the center c1, as shown by arrows in FIG. Are shifted to both sides with a center c3a, c3b. At this time, if the position of the outer edge in the longitudinal direction of each magnet embedding slot 13b is not changed, each magnet embedding slot 13b will stand at an angle closer to parallel to the central axis B (first). Three arrangement P3). As a result, the permanent magnets 16 embedded in the magnet embedding slots 13 b are increasingly disposed at positions on the radially outer side of the rotor core 11.

  Thus, by shifting the position of the center of the innermost magnet buried slot 13b radially inward from the positions of the centers of the intermediate layer slot 14 and the outermost layer slot 15 (center c1 → center c2), the magnet buried slot The entire area of the permanent magnet 16 arranged at 13b approaches the magnetizing coil 100 used for magnetization. As a result, it becomes easier to magnetize the entire region of the innermost permanent magnet material than in the case of the first arrangement P1. Then, by shifting the center of the magnet burying slot 13b shifted radially inward to both sides with the central axis B interposed therebetween (center c2 → center c3a, c3b), the entire area of the permanent magnet 16 disposed in the magnet burying slot 13b However, it becomes closer to the magnetized coil 100 and it becomes easier to magnetize the entire area of the innermost permanent magnet material.

  Even when the magnet embedding slot 13b takes a shape other than the arc shape, the center when the shape is approximated to the arc 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-described central arrangement, a particularly high effect can be obtained in terms of improving the efficiency of magnetization. Similarly, the slots constituting the outer layer, here the intermediate layer slot 14, are also located radially inward of the rotor core 11, compared to the outer slot, here the outermost layer slot 15. As such, it may be configured. Furthermore, the center of the slot divided into two may be shifted to both sides with the central axis B interposed therebetween. With these configurations, an effect of improving the magnetization efficiency can be obtained in the permanent magnet embedded in the slot of the layer.

  Hereinafter, the present invention will be described in detail using examples. Here, the influence on the mechanical strength, the distribution of the magnetizing magnetic field, and the output torque due to the difference in the position of the permanent magnet in the slot was verified.

[1] Examination of mechanical strength First, the effect of the arrangement of the permanent magnets in the slot 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 a conventional general form, in which the permanent magnet has an inner magnet arrangement, and is arranged close to the end portion on the inner side in the longitudinal direction of the slot. Here, the slot has three layers, and permanent magnets are arranged in the inner magnet arrangement in all slots including the outermost layer. A flux barrier is not formed.

  In the second model, as in the first embodiment of the present invention, the permanent magnet has an outer magnet arrangement, and is arranged close to the end portion on the outer side in the longitudinal direction of the slot. Again, the slot has three layers, and permanent magnets are arranged in the outer magnet arrangement in all slots including the outermost layer. A flux barrier is not formed.

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

  When the respective rotors of the three models were axially rotated, the distribution of stress applied to each part of the rotor by centrifugal force was analyzed. The parameters used for the simulation are summarized in Table 1.

(result)
FIG. 6 shows the distribution of principal stress obtained by 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 a flux barrier. Show.

  When comparing the stress distributions in FIGS. 6A, 6B, and 6C, both models show similar results in the form of the stress distribution and the magnitude of the stress applied to each position. Yes. The maximum value of the stress is about the same. Moreover, in any model, the behavior that the stress is concentrated locally is not seen.

  From this, it can be seen that the stress applied to the rotor core at the time of rotor rotation is comparable regardless of whether the inner magnet arrangement or the outer magnet arrangement is adopted, and whether or not the flux barrier is present. That is, even when the outer magnet arrangement is adopted, the same mechanical strength as that of the inner magnet arrangement can be ensured in the rotor core.

[2] Comparison of magnetization magnetic field distribution Next, it was analyzed how the distribution of the magnetization magnetic field changes depending on the arrangement of the permanent magnets in the slot.

(analysis method)
The following three types of rotor models were prepared. The first was the same as the first model used for the examination of the mechanical strength described above. That is, it has an inner magnet arrangement and does not have a flux barrier. Second, the same model as the third model used for the examination of the mechanical strength was adopted. That is, in the outer magnet arrangement, a thin flux barrier having the same thickness as the innermost layer slot is provided between the slots of the innermost layer. Third, a new model was prepared by thickening the flux barrier based on the second model. That is, the outer magnet arrangement has a thick flux barrier between the slots of the innermost layer.

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

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

(result)
FIG. 7 shows the distribution of the magnetization magnetic field obtained by simulation for each model. (A) shows the case where the inner magnet arrangement is taken, (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 in (a) to (c).

  In FIG. 7, when comparing the strength of the magnetic field applied to the permanent magnet material of each layer embedded in each slot, (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, (c) it becomes strong in order in the case of having a thick flux barrier by outer magnet arrangement. This tendency is greatest in the permanent magnet material embedded in the slot of the innermost layer. (A) In the case of the inner magnet arrangement, the magnetizing magnetic field is generated at the inner portion in the thickness direction of the permanent magnet material. Compared with the permanent magnet material embedded in the outer portion of the permanent magnet material in the thickness direction and the slots of the outer two layers, the magnetization magnetic field is significantly weakened. On the other hand, when (b) the outer magnet arrangement has a thin flux barrier, the thickness direction of the permanent magnet material embedded in the innermost slot is also in the thickness direction except for the vicinity of the inner end in the longitudinal direction. A magnetizing magnetic field substantially equal to that of the outer portion is applied. Further, (c) when the outer magnet arrangement has a thick flux barrier, a strong magnetic field is applied almost uniformly at each portion of the permanent magnet material embedded in the three layers of slots.

  FIG. 8 (a) compares and shows the minimum value of the magnetization magnetic field on the permanent magnet material in the magnetization magnetic field distribution of each model of FIGS. 7 (a) to 7 (c). Here, normalization is performed with reference to the value in the case of the inner magnet arrangement of (a), and the result is displayed. Note that the reference numerals (a) to (c) in FIG. 8 correspond to those in FIG.

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

  As shown in FIGS. 7A to 7C, when magnetization is performed under the same conditions, the current flowing through the magnetizing coil increases as the magnetizing magnetic field applied to each part of the permanent magnet material is weaker. 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 magnetizing field applied when the magnetizing field is applied under the same conditions. FIG. 8B shows the result of estimating the current required for magnetization in each model based on the result of FIG. Again, normalization is performed based on the value in the case of the inner magnet arrangement of (a), and the result is displayed.

  According to FIG. 8 (b), the current required for magnetization can be smaller when the outer magnet is arranged and the flux barrier is provided than when the inner magnet is arranged. In the outer magnet arrangement, if the flux barrier is made thicker, the required amount of current is further reduced, and is reduced to 80% or less compared to the case of the inner magnet arrangement.

  From the above, it can be seen that by taking the outer magnet arrangement, a stronger magnetic field can be applied to the permanent magnet material than in the case of taking the inner magnet arrangement. And a magnetizing magnetic field can be further strengthened by providing a thick flux barrier at a position between slots corresponding to the center of the magnetic pole. As a result, by adopting the outer magnet arrangement and further providing a thick flux barrier between the slots, the current required to achieve complete magnetization can be reduced, and the capacity of the magnetized power supply can be reduced. Smaller ones can be used.

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

(analysis method)
The following two types of rotor models were prepared. The first model relates to a conventional general form, in which the permanent magnet has an inner magnet arrangement and is arranged close to the end portion on the inner side in the longitudinal direction of the slot. Here, three slots are provided, but no permanent magnet is arranged in the outermost layer slot, and permanent magnets are arranged in an inner magnet arrangement in the intermediate layer and innermost layer slots. A flux barrier is not formed.

  In the second model, as in the first embodiment of the present invention, the permanent magnet has an outer magnet arrangement and is arranged close to the end portion on the outer side in the longitudinal direction of the slot. Here, the slot has three layers, but the permanent magnet is not disposed in the outermost layer slot, and the permanent magnet is disposed in the intermediate layer and the innermost layer slot in the outer magnet arrangement. A flux barrier is not formed.

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

  The parameters used for the simulation are as shown in Table 1 above. The magnetic flux from the permanent magnet 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.

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

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

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this 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, the effect of improving the magnetization efficiency and the effect of improving the reluctance torque are obtained. In the second embodiment, the flux barrier 13c is provided, and the centers c3a and c3b when the slot 13 is approximated to an arc shape are arranged at predetermined positions, thereby improving the magnetization efficiency and reluctance. The effect of torque improvement is further enhanced. However, the present invention is not limited to the case where the outer magnet arrangement is adopted, and the case where the permanent magnets 16, 17, 18 are arranged at arbitrary positions in the slots 13, 14, 15 has been described 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 in an arc shape at predetermined positions, the effect of improving the efficiency of magnetization, and the reluctance The effect of improving torque can be obtained.

1 Motor (rotary electric machine)
10, 10 'rotor (permanent magnet rotor)
11 Rotor core 12 Hollow portion 13, 13 ′ Innermost layer slot 13 a Air gap portion 13 b Magnet buried slot 13 c Flux barrier 14 Middle layer slot 14 a Air gap portion 15 Outermost layer slot 16 Innermost layer permanent magnet 17 Middle layer permanent magnet 18 Outer permanent magnets 19 and 20 Bridge 30 Stator (stator)
50 Air gap 100 Magnetized coil c1 Center c2 of the middle layer and outermost layer slots Center positions c3a and c3b obtained by shifting the center c1 radially inward Center A of the innermost layer slot obtained by shifting the center c2 to both sides of the central axis B Directional axis B Central axis H Magnetizing magnetic field R Center of rotation P1 First arrangement P2 Second arrangement P3 Third arrangement

Claims (9)

In a permanent magnet rotor having a rotor core and a permanent magnet embedded in a slot provided in the rotor core and constituting a magnetic pole,
In the cross section orthogonal to the rotation center of the rotor core, the slot is changed in distance from the rotation center of the rotor core along the longitudinal direction.
An outer magnet arrangement in which, along the longitudinal direction of the slot, a portion occupied by the permanent magnet is provided at a position radially outer than the portion not occupied by the permanent magnet with respect to the rotation center of the rotor core. Permanent magnet rotor taking.   A plurality of the slots are arranged in layers in the radial direction of the rotor core, and at least one of the plurality of slots arranged in layers other than the slots arranged on the outermost side of the rotor core is the permanent. The permanent magnet rotor according to claim 1, wherein a magnet is embedded in the outer magnet arrangement.   The permanent magnet rotation according to claim 2, wherein the permanent magnet is embedded in the outer magnet arrangement in at least the innermost slot of the rotor core among the plurality of slots arranged in layers. Child.   The center when the shape of the slot in which the permanent magnet is embedded approximates a circular arc is closer to the inside of the rotor core than the center when the slot provided outside the rotor core approximates the circular arc than the slot. The permanent magnet rotor according to claim 2, which is located.   5. The permanent magnet rotor according to claim 1, wherein the permanent magnet is embedded in the positions of both ends along the longitudinal direction of the slot in the outer arrangement. 6.   The center when the shape of each of the permanent magnets embedded at both ends of the slot is approximated to an arc is the center of each permanent magnet with a straight line passing through the center of the slot along the radial direction of the rotor core. The permanent magnet rotor according to claim 5, wherein the permanent magnet rotors are separated from each other toward the side opposite to the side on which the magnet is provided.   The slot is divided into two magnet burying slots located at both ends in the longitudinal direction where the permanent magnets are buried, and a flux barrier located between the two magnet burying slots and where the permanent magnets are not buried. The permanent magnet rotor according to claim 5 or 6.   The permanent magnet rotor according to claim 7, wherein a thickness of the flux barrier is larger than a thickness intersecting with a longitudinal direction of the permanent magnet embedded in the magnet embedding slot.   A rotary electric machine having the permanent magnet rotor according to any one of claims 1 to 8.