JP2010200480A - Embedded magnetic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve cost reduction by using a ferrite magnet for a permanent magnet of a rotor so as not to cause torque deterioration. <P>SOLUTION: An embedded magnet motor 10 includes a stator 13 having a laminate core having a three-phase winding 11 wound therearound, and a rotor 16 having a circular laminate core in which the outer circumference is spaced from the stator 13 with a gap length G1 of a predetermined dimension and the inner circumference is fixed to a rotating shaft. In the motor 10, rectangular slits 21 having a longitudinal direction axis following the imaginary radiation line extending from the center of the circular shape and rectangular permanent magnets 22 having a longitudinal direction following the imaginary radiation line are disposed on the surface of the circular shape of the rotor 16 so as to be 1/2 of the number of motor poles P alternately at a predetermined interval in the circumferential direction of the circular shape, and segment regions 23 at as many parts as the number of motor poles P between each of the slits 21 and the permanent magnets 22, and the segment regions 23 are alternately magnetized in N- and S-poles along the circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an embedded magnet motor used in a vehicle such as a hybrid vehicle or an electric vehicle.

  Conventionally, as an embedded magnet type motor, for example, there is a rotor of a permanent magnet type synchronous rotating electric machine described in Patent Document 1. As shown in FIG. 1, this configuration includes a rotor core 1 in which thin plates are laminated in the axial direction, a rectangular permanent magnet insertion hole 2 provided in the rotor core 1 at a predetermined pitch, and a permanent magnet inserted into the permanent magnet insertion hole 2. In a rotor of a permanent magnet type synchronous rotating electric machine composed of magnets 4a, permanent magnet insertion holes 2 are provided every other pole pitch, and permanent magnets 4a having the same radial polarity are inserted, and the rotor of the permanent magnet type synchronous rotating electric machine. Configure. The permanent magnet is divided in the axial direction, the sum of the respective lengths is made shorter than the axial length of the permanent magnet insertion hole 2, and both end surfaces of the rotor core are aligned or inserted deeper than the end surface to obtain the permanent magnet insertion hole 2. A magnetic space is formed in the axial direction. Furthermore, it is divided into three in the axial direction, the height of the insertion hole provided in the central rotor core is made higher than that on both sides, a permanent magnet with a low energy product is installed in the central insertion hole, and a high energy product is installed in the insertion holes on both sides. It is configured by inserting a permanent magnet.

JP-A-8-107639

  However, in Patent Document 1 described above, in order to generate high torque in the rotor, it is generally considered that a rare earth magnet is embedded in a permanent magnet in the axial direction and the iron core attracting torque near the surface of the magnetic pole is utilized. There is a problem that rare earth magnets are expensive. Therefore, it is conceivable to replace it with an inexpensive ferrite magnet, but it is necessary to increase the thickness of the ferrite with a weak coercive force so that sufficient magnetic force is obtained. There is a problem that torque cannot be exhibited. If they are not thickened, there is a problem that the torque may be reduced due to irreversible demagnetization due to ferrite having a weak coercive force when a demagnetizing field is applied from the stator during field weakening control. In the rotor of the above-mentioned Patent Document 1, a configuration in which a ferrite magnet is combined with a rare earth magnet and a small amount of the rare earth magnet is reduced is adopted. However, since the configuration basically uses a rare earth magnet, the cost increases accordingly. It has become.

  The present invention has been made in view of such circumstances, and provides an embedded magnet motor that can reduce the cost by using a ferrite magnet as a permanent magnet of a rotor so as not to cause a reduction in torque. For the purpose.

  The invention according to claim 1, which has been made to achieve the above object, has a stator having a laminated iron core around which a three-phase winding is wound, and the stator has a gap length of a predetermined dimension and the outer periphery is spaced apart. And a rotor having an annular laminated iron core whose inner periphery is fixed to a rotation shaft, and a rectangular whose longitudinal axis is along the virtual radiation extending from the center of the ring on the annular surface of the rotor Each having a slit of a rectangular shape and rectangular permanent magnets whose longitudinal axes follow the virtual radiation are alternately arranged at predetermined intervals in the circumferential direction of the ring, each being ½ of the number of motor poles P. Between the slit and the permanent magnet, segment areas of P number of motor poles (iron core area near the surface) are formed, and these segment areas are alternately magnetized into N pole and S pole along the circumferential direction. What I did And features.

  According to this configuration, when field-weakening control is performed from the stator to the rotor, the slit and the permanent magnet are arranged in parallel when viewed from the stator. Also flows. Accordingly, it is possible to prevent application of an excessive demagnetizing field to the permanent magnet and to prevent a decrease in torque in the high speed rotation region. Further, since the number of permanent magnets may be 1/2 of the number of poles P and is disposed between the slits 21, the width of one permanent magnet can be widened, thereby increasing the magnetic force. Therefore, when the permanent magnet is a ferrite magnet, the torque does not decrease, and when the permanent magnet is a rare earth magnet, the torque is improved.

  According to a second aspect of the present invention, in the embedded magnet motor according to the first aspect, the width of the slit in a direction perpendicular to the longitudinal axis along the virtual radiation is a gap length between the stator and the rotor. The width of the permanent magnet is smaller than the width of the permanent magnet in the direction perpendicular to the longitudinal axis along the virtual radiation.

  According to this configuration, since the width of the slit is wider than the gap length, the magnetic flux from the permanent magnet is less likely to flow into the slit and more easily to the stator through the gap, and the slit width is larger than the width of the permanent magnet. Since it is narrow, when a reverse magnetic field is applied from a stator that causes a field weakening action in a high-speed rotation region or the like, the reverse magnetic field is easier to flow through the slit than the magnet, and as a result, the reverse magnetic field to the permanent magnet is relaxed. The effect is obtained.

  According to a third aspect of the present invention, in the embedded magnet type motor according to the first or second aspect, the slit is disposed at the center or substantially at the center between the permanent magnets.

  According to this configuration, since the magnetic flux generated in the permanent magnet and the slit by the reversed field can flow in a balanced manner, torque can be stably generated and the rotor can be smoothly rotated.

  The invention according to claim 4 is the embedded magnet type motor according to any one of claims 1 to 3, wherein the permanent magnet is arranged such that a longitudinal axis of the permanent magnet is inclined with respect to the virtual radiation. It is characterized by being.

  According to this configuration, since the area of the permanent magnet in the direction facing the stator is increased, a larger amount of magnetic flux due to the reverse magnetic field can be flowed, and the torque can be increased.

  The invention according to claim 5 is the embedded magnet type motor according to any one of claims 1 to 4, wherein the permanent magnet is a ferrite magnet.

  According to this configuration, since the permanent magnet can be an inexpensive ferrite magnet, the cost of the embedded magnet motor can be reduced.

  A sixth aspect of the present invention is the embedded magnet motor according to any one of the first, third, and fourth aspects, wherein the permanent magnet is a rare earth magnet, and the rare earth magnet is longitudinally along the virtual radiation. The width in the direction orthogonal to the axis is set to a dimension equal to or smaller than the width in the direction orthogonal to the longitudinal axis along the virtual radiation of the slit.

  According to this configuration, even if the permanent magnet is a rare earth magnet, the width of the rare earth magnet is narrow and the number of motor poles is ½, so that the amount of rare earth magnet used can be reduced overall. The motor manufacturing cost can be reduced correspondingly.

  As described above, according to the present invention, there is an effect that it is possible to provide an embedded magnet motor that can reduce the cost by using a ferrite magnet as a permanent magnet of a rotor so as not to cause a reduction in torque. is there.

It is a figure which shows the structure of the rotor of the permanent-magnet-type synchronous rotary electric machine as a conventional embedded magnet type motor. The structure of the embedded magnet type motor which concerns on embodiment of this invention is shown, (a) is sectional drawing of an embedded magnet type motor, (b) is a partial surface view of the rotor of an embedded magnet type motor. It is a partial surface view which shows the other structure of the rotor of the embedded magnet type motor of this embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. However, parts corresponding to each other in all the drawings in this specification are denoted by the same reference numerals, and description of the overlapping parts will be omitted as appropriate.

  2A and 2B show a configuration of an embedded magnet motor according to an embodiment of the present invention. FIG. 2A is a cross-sectional view of the embedded magnet motor, and FIG. 2B is a partial surface view of a rotor of the embedded magnet motor.

  An embedded magnet motor (IPM motor) 10 shown in FIG. 2 is mounted on an electric vehicle, for example, and includes a three-phase winding 11 connected to an inverter (not shown) for power conversion, and the three-phase winding. 11 is provided with a stator core 13 having a laminated iron core 12 wound thereon, the outer circumference is spaced apart from the stator 13 with a gap length G1 of 0.3 mm, and the inner circumference is fixed to the rotary shaft 14. A rotor 16 having an annular laminated iron core 15 is provided.

  The feature of the present embodiment is that an elongated rectangular slit 21 along the longitudinal direction on the virtual radiation extending from the annular center is formed on the annular surface of the rotor 16, and the rectangular shape along the virtual radiation. Permanent magnets 22 made of ferrite magnets are alternately arranged at predetermined intervals in the circumferential direction, each being ½ of the number of poles P of the motor, and the number of poles P is between each slit 21 and the permanent magnet 22. Segment regions 23 are formed, and these segment regions 23 are configured to be alternately magnetized into N and S poles along the circumferential direction. Here, it is assumed that the number of poles is 8, and four slits 21 and four permanent magnets 22 are arranged. An arrow Y1 is the rotation direction of the rotor 16.

  Further, the width 21w in the direction orthogonal to the virtual radiation of the slit 21 is larger than the gap length G1 between the stator 13 and the rotor 16 and smaller than the width 22w in the direction orthogonal to the virtual radiation of the permanent magnet 22. Here, it is assumed that when the gap length G1 is 0.3 mm and the width 22w of the permanent magnet 22 is 8 mm, the width 21w of the slit 21 is 1.5 mm.

  In the embedded magnet motor 10 having such a configuration, it is assumed that field weakening control is performed from the stator 13 to the rotor 16 in a driving region that exceeds the limit voltage in a high-speed rotation region or the like. In this case, since the slit 21 and the permanent magnet 22 are arranged in parallel when viewed from the stator 13, the magnetic flux generated by the reverse magnetic field from the stator 13 is represented by φ22 and φ21 in FIG. It flows to 21. That is, not only the permanent magnet 22 but also the slit 21 flows through the segment region 23 in a distributed manner, so that this becomes reluctance torque. The torque of the rotor 16 is the sum of the magnet torque generated by the magnetic flux φ22 flowing through the permanent magnet 22 and the reluctance torque.

  Therefore, the excessive magnetic flux φ22 due to the demagnetizing field does not flow only in the permanent magnet 22, but the magnetic flux φ21 flows in the slit 21 in a distributed manner. In order to distribute the magnetic flux φ21 optimally by dispersing in this way, the width 21w of the slit 21 is made wider than the gap length G1. Further, the reason why the width 21w is narrower than the width 22w of the permanent magnet 22 is to prevent the magnetic flux φ21 from being distributed excessively.

  Further, when the field weakening control is not performed, the width 21w of the slit 21 is wider than the gap length G1 and narrower than the width 22w of the permanent magnet 22, so that the leakage of the magnetic flux φ21 to the slit 21 also occurs with respect to the permanent magnet 22. And relatively few. Further, since the permanent magnets 22 may be ½ the number of poles P and are arranged between the slits 21, the width 22 w of each permanent magnet 22 can be widened, thereby increasing the magnetic force and torque. Never came down.

  When the embedded magnet type motor 10 in which such a ferrite magnet is disposed in the rotor 16 as a permanent magnet 22 is compared with an embedded magnet type motor in which a neodymium magnet as a conventional rare earth magnet is disposed in the rotor as a permanent magnet. Further, the torque and the demagnetization resistance are almost equal, and the effect that the cost of the used permanent magnet 22 is about 1/3 is obtained. That is, it is possible to reduce the cost by using a ferrite magnet as the permanent magnet of the rotor 16 so as not to reduce the torque.

  As described above, the embedded magnet type motor 10 of the present embodiment has the rectangular slit 21 whose longitudinal axis extends along the virtual radiation extending from the annular center on the annular surface of the rotor 16, and the longitudinal axis along the virtual radiation. Are arranged at intervals of a predetermined interval in the annular circumferential direction, and the number of motor poles P is alternately arranged between the slits 21 and the permanent magnets 22. The segment regions 23 having the number P of motor poles are formed, and these segment regions 23 are alternately magnetized to the N and S poles along the circumferential direction.

  Thus, when field weakening control is performed from the stator 13 to the rotor 16, the slit 21 and the permanent magnet 22 are arranged in parallel when viewed from the stator 13, so that the magnetic flux generated by the reverse magnetic field from the stator 13 is generated by the permanent magnet 22. Not only flows into the slit 21 but also. Accordingly, it is possible to prevent application of an excessive demagnetizing field to the permanent magnet 22 and to prevent a decrease in torque in the high speed rotation region. Further, since the number of permanent magnets 22 may be ½ of the number of poles P and disposed between the slits 2121, the width of one permanent magnet 22 can be widened, thereby increasing the magnetic force. Therefore, when the permanent magnet 22 is a ferrite magnet, the torque does not decrease. When the permanent magnet 22 is a rare earth magnet, the torque is improved.

  The width of the slit 21 in the direction orthogonal to the longitudinal axis along the virtual radiation is wider than the gap length G1 between the stator 13 and the rotor 16 and the longitudinal axis along the virtual radiation of the permanent magnet 22 The dimension is narrower than the width in the orthogonal direction.

  Accordingly, since the width of the slit 21 is wider than the gap length G1, the magnetic flux from the permanent magnet 22 hardly flows into the slit 21 and easily flows toward the stator through the gap G1, and further, the width of the slit 21 is the width of the permanent magnet 22. Since it is narrower than the width, when a reverse magnetic field from the stator 13 that causes a field weakening action in a high-speed rotation region or the like is applied, the reverse magnetic field is more likely to flow through the slit 21 than the permanent magnet 22, and as a result, reverse to the permanent magnet 22. The magnetic field will be relaxed.

  Further, the slit 21 is arranged at the center or substantially at the center between the permanent magnets 22. As a result, the magnetic flux generated in the permanent magnet 22 and the slit 21 by the reverse field can flow in a well-balanced manner, so that torque can be stably generated and the rotor 16 can be rotated smoothly.

  Furthermore, the permanent magnet 22 is disposed so that the longitudinal axis of the permanent magnet 22 is oblique to the virtual radiation. As a result, the area of the permanent magnet 22 in the direction facing the stator 13 is increased, so that a larger amount of magnetic flux due to the reverse magnetic field can be caused to flow, and the torque can be increased.

  In addition, as shown in FIG. 3, the permanent magnet is a rare earth magnet 32 such as a neodymium magnet, and the width 32w of the rare earth magnet 32 in the direction perpendicular to the longitudinal axis along the virtual radiation is equal to or less than the width 19w of the slit 21. It is good also as a dimension. In the case of this configuration, even if the permanent magnet is the rare earth magnet 32, the width 32w of the rare earth magnet 32 is narrow and the number of motor poles is ½, so that the amount of the rare earth magnet 32 used is reduced overall. The motor manufacturing cost can be reduced accordingly.

DESCRIPTION OF SYMBOLS 10 Embedded magnet type motor 11 Three-phase winding 12 Laminated iron core 13 Stator 14 Rotating shaft 15 Laminated iron core 16 Rotor 21 Slit 22 Permanent magnet 23 Segment area 32 Rare earth magnet

Claims (6)

A stator having a laminated iron core around which three-phase windings are wound, and a rotor having an annular laminated iron core having an outer circumference spaced apart from the stator with a gap length of a predetermined dimension and an inner circumference fixed to a rotating shaft; In an embedded magnet type motor comprising:
On the annular surface of the rotor, a rectangular slit whose longitudinal axis extends along virtual radiation extending from the annular center, and a rectangular permanent magnet whose longitudinal axis extends along the virtual radiation, The motor pole number P is alternately arranged at predetermined intervals in the circumferential direction, and segment areas of P motor pole numbers are formed between the slits and the permanent magnets. An embedded magnet motor characterized in that it is magnetized alternately in N and S poles along the direction.   The width of the slit in the direction orthogonal to the longitudinal axis along the virtual radiation is wider than the gap length between the stator and the rotor and orthogonal to the longitudinal axis of the permanent magnet along the virtual radiation. The embedded magnet motor according to claim 1, wherein the embedded magnet motor has a size smaller than a width in a direction in which the motor is driven.   The embedded magnet type motor according to claim 1, wherein the slit is arranged at a center or a substantially center between the permanent magnets.   The embedded magnet type motor according to any one of claims 1 to 3, wherein the permanent magnet is disposed such that a longitudinal axis of the permanent magnet is inclined with respect to the virtual radiation.   The embedded magnet motor according to claim 1, wherein the permanent magnet is a ferrite magnet.   The permanent magnet is a rare earth magnet, and the width of the rare earth magnet in the direction perpendicular to the longitudinal axis along the virtual radiation is smaller than the width of the slit in the direction perpendicular to the longitudinal axis along the virtual radiation. The embedded magnet motor according to claim 1, wherein the motor is an embedded magnet motor.

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