JP2017147810A - Embedded magnet type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an embedded magnet type motor that is able to increase torque and reduce diamagnetic field.SOLUTION: An embedded magnet type motor 1 comprises: a stator 2 around which a coil 7 is wound; a rotor 3 disposed so as to freely rotate with respect to the stator 2; and a plurality of rectangular parallelepiped magnets 5 embedded in the rotor 3. A side face of the magnet 5 is a rectangle, having long sides and short sides. When the side face is divided into a grid pattern by elements A having a magnetizing direction perpendicular to the long sides and elements B having a magnetizing direction inclined at predetermined angle α counterclockwise with respect to the magnetizing direction of the elements A, the elements B are respectively disposed at the left upper and right lower corners of a diagonal, and the elements A are arranged at the remaining parts. The predetermined angle α satisfies a relation of 0°<α≤15°.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an interior magnet type motor.

  Conventionally, as a technique in such a field, for example, there are those described in the following patent documents. The interior magnet type motor described in Patent Document 1 includes a stator, a rotor, and a long magnet that is embedded in the rotor such that the longitudinal direction thereof follows the rotation direction of the rotor. When the magnet is divided into a plurality of regions in the longitudinal direction, the magnetization direction of the central region is set to a direction perpendicular to the longitudinal direction of the magnet, and the magnetization direction of the end region is inclined to face the inside of the magnet. Is set. In this way, the torque of the motor can be increased for the same input current by suppressing the leakage of magnetic flux and improving the magnetic flux density.

Japanese Patent Application Laid-Open No. 2014-7796

  However, the above-described embedded magnet type motor cannot be said to set the optimum magnetization direction. That is, a demagnetizing field is generated in the magnet in a direction opposite to the magnetization direction of the magnet, and the generation of this demagnetizing field reduces the magnetic flux density from the magnet surface, resulting in a decrease in torque. In addition, an incident magnetic field from the stator (hereinafter referred to as a stator incident magnetic field) adds a decomposition component of the stator incident magnetic field in the same direction as the demagnetizing field. For this reason, since the demagnetizing field of a magnet becomes large, it not only inhibits an increase in torque, but also leads to an increase in cost associated with ensuring coercive force. On the other hand, since the above-described embedded magnet type motor has not been investigated, there is a problem that it is difficult to increase the torque and that the demagnetizing field cannot be reduced.

  The present invention has been made to solve such a technical problem, and an object thereof is to provide an embedded magnet type motor capable of increasing torque and reducing demagnetizing field.

  An embedded magnet type motor of the present invention that solves the above problems is embedded in a stator around which a coil is wound, a rotor that is rotatably provided to the stator, a shaft that is fixed to the rotor, and a rotor. A magnet having a plurality of rectangular parallelepiped magnets, wherein a side surface of the magnet has a long side and a short side, and the side surface has a magnetization direction perpendicular to the long side. When dividing into a lattice shape by a first element having and a second element having a magnetization direction inclined at a predetermined angle counterclockwise with respect to the magnetization direction of the first element, the element is positioned on at least one diagonal line The second element is disposed at each of the two corners, and the first element is disposed at the other part, and the predetermined angle is greater than 0 ° and less than or equal to 15 °. .

  In the interior magnet type motor according to the present invention, the side surface of the magnet has a first element having a magnetization direction perpendicular to the long side of the side surface and a predetermined angle counterclockwise with respect to the magnetization direction of the first element. When the second element having the magnetization direction inclined at is divided into a lattice shape, the second elements are respectively arranged at two corners located on at least one diagonal line. By tilting the magnetization direction of the corner portion in this way, the magnetic path becomes longer than in the case where the corner is not tilted, so that the effect of reducing the demagnetizing field is achieved. For this reason, the magnetic flux density from the magnet surface increases, and the torque of the motor can be increased.

  In addition, by degrading the magnetization direction of the corner portion, the decomposition component of the demagnetizing field direction in the stator incident magnetic field can be reduced, so that the demagnetizing field can be reduced. As the demagnetizing field is reduced, the coercive force of the magnet can be reduced, so that the use of rare earth elements or the like can be reduced, and the manufacturing cost can be reduced. Furthermore, since the predetermined angle of the second element is in the range of greater than 0 ° and less than 15 ° counterclockwise with respect to the magnetization direction of the first element, torque can be increased and the demagnetizing field can be reduced in a well-balanced manner. It becomes possible.

  Further, in the embedded magnet type motor according to the present invention, the plurality of magnets are arranged on the left and right sides of the middle magnet, the middle magnet arranged so that the long side of the side surface is along the rotation direction of the rotor. And a plurality of magnet sets comprising a left magnet and a right magnet formed in a triangular shape with the middle magnet, and the second element is provided at the upper left corner and the lower right corner on the side surface of the magnet. Are arranged such that the upper left corner of the middle magnet faces the stator side, and the left magnet is arranged such that the upper left corner of the middle magnet is inclined toward the stator side. The magnet is preferably arranged so that the upper left corner is inclined toward the shaft. In this way, it is possible to further increase the torque and reduce the demagnetizing field with a better balance.

  According to the present invention, it is possible to increase the torque and reduce the demagnetizing field.

It is a top view showing an embedded magnet type motor concerning an embodiment. It is an enlarged plan view showing a 1/8 model of an embedded magnet type motor. It is a figure which shows the number when dividing | segmenting the side surface of a magnet. It is a figure which shows the arrangement position of the elements A and B. FIG. (A) It is a schematic diagram which shows the magnetization state of the element A, (b) It is a schematic diagram which shows the magnetization state of the element B, (c) It is a schematic diagram which shows the comparison of the element A and the element B. (A) It is a schematic diagram which shows the magnetic field state in the element A, (b) It is a schematic diagram which shows the magnetic field state in the element B. It is a figure which shows the angle of a magnetization direction. It is a map which shows the relationship between the torque which concerns on the result of simulation, and a demagnetizing field total. It is a figure which shows an arrangement | positioning pattern. It is a map which shows the position of each comparative example. It is a figure which shows the arrangement pattern of each comparative example.

  Hereinafter, an embedded magnet type motor according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an embedded magnet type motor according to the embodiment. The embedded magnet type motor 1 is used, for example, as a drive source for a hybrid vehicle or an electric vehicle, and includes a stator 2 disposed on the outer peripheral portion, a rotor 3 rotatably provided inside the stator 2, and a rotor 3. And a plurality of magnets 5 embedded in the rotor 3.

  The stator 2 includes a stator iron core 6 formed in an annular shape by an electromagnetic steel plate and a plurality of coils 7 wound around the stator iron core 6. The coils 7 are arranged at equal intervals on the inner peripheral side of the stator 2, and a rotating magnetic field for rotating the rotor 3 is generated when the coil 7 is energized.

  The rotor 3 has a substantially disc-shaped rotor core 8 in which a shaft hole 9 is formed in the central portion. The rotor core 8 is formed, for example, by laminating disc-shaped electromagnetic steel plates, and functions as a magnetic path of the magnetic flux (reluctance torque) of the iron magnetic pole of the stator 2 and the magnetic flux of the magnet 5 (magnet torque). The shaft 4 is inserted into the shaft hole 9 of the rotor core 8 and is fixed to the rotor core 8.

  The magnet 5 is a permanent magnet and has a rectangular parallelepiped shape. The side surface of the magnet 5 has a rectangular shape having a long side and a short side. As shown in FIG. 1, the magnets 5 are arranged according to a predetermined rule along the rotation direction of the rotor 3 (the arrow direction shown in FIG. 1). Specifically, a magnet set 10 including a left magnet 5L, a middle magnet 5M, and a right magnet 5R is arranged every 45 ° along the rotation direction of the rotor 3. The left magnet 5L, the middle magnet 5M, and the right magnet 5R are substantially triangular.

  FIG. 2 is an enlarged plan view showing a 1/8 model of an embedded magnet type motor. As shown in FIG. 2, in the magnet set 10, the middle magnet 5 </ b> M is positioned on the side closest to the stator 2, and the long side of the side surface is arranged along the rotational direction of the rotor 3. The left magnet 5L is disposed on the left side of the middle magnet 5M, and the right magnet 5R is disposed on the right side of the middle magnet 5M. The left magnet 5L and the right magnet 5R have an inverted C shape so that the distance decreases as it goes to the inner side of the rotor 3 (that is, the shaft 4 side).

  Further, in the magnet set 10, the side of the middle magnet 5 </ b> M adjacent to the stator 2 is an N pole, and the opposite side is an S pole. The left magnet 5L and the right magnet 5R are arranged so that the polarities are opposite to each other between the middle magnet 5M and the adjacent magnetic pole. That is, since the left magnet 5L is closer to the S pole than the N pole of the middle magnet 5M, the side adjacent to the middle magnet 5M is the N pole. Similarly, since the right magnet 5R is closer to the S pole than the N pole of the middle magnet 5M, the side adjacent to the middle magnet 5M is also the N pole.

  The magnet 5 is fitted into a magnet slot provided in the rotor core 8, and the resin 11 is filled at both left and right ends thereof. As the resin 11, a thermosetting resin excellent in moldability and heat resistance is used. As the thermosetting resin, an epoxy resin, a polyimide resin, or the like can be used. The magnet 5 is a rare earth magnet such as a neodymium magnet mainly composed of neodymium, iron and boron, or a samarium cobalt magnet mainly composed of samarium and cobalt. Besides this, a ferrite magnet, an alnico magnet, or the like may be used.

  In the present embodiment, the side surface of the magnet 5 is divided into a lattice shape by a plurality of elements. Specifically, as shown in FIG. 3, the side surface of the magnet 5 is divided into 10 parts in the direction along the long side and into 3 parts in the direction along the short side, and is equally divided into a total of 30 elements. Yes. When these elements are numbered in order along the short side and the long side, as shown in FIG. 1-No. 30. At this time, the upper left, lower left, upper right, and lower right corners are respectively indicated by element numbers. 1, no. 3, no. 28 and no. 30 and element no. 1 and element no. 30 is located on one diagonal line, and element no. 3 and element no. 28 is located on another diagonal line. In addition, as a magnetic pole of the magnet 5, the lower side is an S pole and the upper side is an N pole.

  Element No. 1-No. 30 is roughly divided into an element A and an element B having the same shape but different magnetization directions. That is, element No. 1-No. 30 includes elements A and B having different magnetization directions. The element A corresponds to the “first element” recited in the claims, and the magnetization direction is a direction perpendicular to the long side of the side surface. On the other hand, the element B corresponds to the “second element” recited in the claims, and its magnetization direction is inclined at a predetermined angle α counterclockwise from the direction perpendicular to the long side of the side surface. . In other words, the magnetization direction of the element B is inclined at a predetermined angle α counterclockwise with respect to the magnetization direction of the element A. As shown in FIG. 4, in this embodiment, the element No. 1-No. 30 of element No. 30 located on the diagonal line. 1 and element no. Element B is arranged at 30 and element A is arranged at all other parts.

  Hereinafter, the magnetization state and the magnetic field state of the element A and the element B will be described with reference to FIGS.

  5A is a schematic diagram showing the magnetization state of element A, FIG. 5B is a schematic diagram showing the magnetization state of element B, and FIG. 5C is a comparison between element A and element B. FIG. It is a schematic diagram shown. In these drawings, the white arrow indicates the magnetization of the element, the hatched arrow indicates the demagnetizing field, and the black arrow indicates the magnetic flux density from the surface.

  As shown in FIG. 5A, in the element A, since the magnetization direction is a direction perpendicular to the long side of the side surface, the magnetization is directed from the bottom to the top. Therefore, a demagnetizing field is generated in the element A in a direction opposite to the magnetization direction. The demagnetizing field is proportional to the magnitude of magnetization, and the demagnetizing field becomes larger as the thickness in the magnetization direction is thinner (that is, the shorter the magnetic path is). And since the magnetic flux density from the magnet surface reduces by generation | occurrence | production of a demagnetizing field, and the torque of a motor falls, all the magnetization in the element A cannot be utilized. The motor torque here means the combined torque of the above-described reluctance torque and magnet torque.

  As shown in FIG. 5B, in the element B, the magnetization direction is inclined at a predetermined angle α counterclockwise with respect to the magnetization direction of the element A. Since the path becomes longer, the thickness in the magnetization direction becomes thicker (see FIG. 5C). As a result, the demagnetizing field decreases and the magnetic flux density from the magnet surface increases, so that the motor torque can be increased.

  6A is a schematic diagram showing a magnetic field state in the element A, and FIG. 6B is a schematic diagram showing a magnetic field state in the element B. FIG. In these drawings, arrows F1 and F1 ′ are magnetization, arrows F2 and F2 ′ are demagnetizing fields, arrows F3 and F3 ′ are stator incident magnetic fields, arrows F4 and F4 ′ are decomposition components 1 of stator incident magnetic fields, and arrows F5 and F5. 'Represents the decomposition component 2 of the stator incident magnetic field. The stator incident magnetic field decomposition component 1 is a component along the direction perpendicular to the demagnetizing field direction, and the stator incident magnetic field decomposition component 2 is a component along the demagnetizing field direction.

  As shown in FIG. 6, in the direction against the magnetization direction of the elements A and B (that is, the direction opposite to the magnetization direction), in addition to the demagnetizing field (internal magnetic field), the decomposition component 2 ( An external magnetic field is further applied. The decomposition component 2 of the demagnetizing field and the stator incident magnetic field constitutes a demagnetizing field. In other words, the demagnetizing field is the sum of the demagnetizing field and the decomposition component in the demagnetizing direction in the stator incident magnetic field. The magnitude (scalar amount) of the demagnetizing field is the sum of the scalar amount of the demagnetizing field and the scalar amount of the decomposition component 2 of the stator incident magnetic field. In the following description, the demagnetizing field may be referred to as the total demagnetizing field.

  When the sum of the demagnetizing field and the decomposition component 2 of the stator incident magnetic field increases, that is, the demagnetizing field increases, it is necessary to increase the coercive force of the magnet 5 against the demagnetizing field in order to prevent demagnetization. In order to increase the coercive force, it is necessary to add a rare earth element to the raw material of the magnet 5. However, since the rare earth element is expensive, there arises a problem that increases the manufacturing cost. Therefore, in order to reduce the manufacturing cost, it is desired to reduce the demagnetizing field.

  Table 1 is a table showing changes in the magnetic field states of the elements A and B.

  As shown in FIG. 6 and Table 1, in element A and element B, the vector value of the stator incident magnetic field does not change, but the magnetic path becomes longer due to the inclination of the magnetization direction, so that the demagnetizing field and stator incident magnetic field decomposition component 2 Both decrease. As a result, the demagnetizing field can be reduced, and the coercive force can be easily secured. As a result, the amount of rare earth element used can be reduced, and the manufacturing cost can be reduced.

  Note that the predetermined angle α of the element B is preferably greater than 0 ° and 15 ° or less, and in this way, an increase in torque and a reduction in the demagnetizing field can be achieved in a well-balanced manner. That is, when the predetermined angle α is 0 ° or less or exceeds 15 °, the torque decreases and the demagnetizing field also decreases. The relative position of the stator field is advanced in order to attract and repel the magnet magnetic force in the rotor and use it as power. Accordingly, the magnetization of the magnet is attracted and repelled with respect to the field of the stator, and in order to function as a motor in the motor structure used in the present invention, the predetermined angle α needs to be larger than 0 ° and not larger than 15 °. It is.

  Here, on the side surface of the magnet 5, when the element B is arranged at the upper left corner (element No. 1) and the lower right corner (element No. 30), respectively, as shown in FIG. The magnet 5M is arranged so that the upper left corner (see the star in FIG. 2) faces the stator 2 side and the lower right corner faces the shaft 4 side. On the other hand, the left magnet 5L is disposed such that the upper left corner (see the star in FIG. 2) is inclined toward the stator 2 and the lower right corner is inclined toward the shaft 4. The right magnet 5R is arranged so that the upper left corner (see the star in FIG. 2) is inclined toward the shaft 4 and the lower right corner is inclined toward the stator 2. In this way, it is possible to further increase the torque and reduce the demagnetizing field with a better balance.

  As described above, according to the embedded magnet type motor 1 according to the present embodiment, it is possible to increase the torque and reduce the demagnetizing field.

  When the above-described embedded magnet type motor 1 is manufactured, for example, first, a plurality of magnet pieces each having the element A or the element B are magnetized by magnetizing the magnet pieces in accordance with the magnetization direction of the element A or the element B. prepare. Next, based on the position shown in FIG. 4, the magnet piece having the element A and the magnet piece having the element B are assembled in order to produce the magnet 5. At this time, the magnet pieces are brought into close contact with each other by magnetic force. Subsequently, the produced magnet 5 is inserted into the magnet slot of the rotor 3, and the gap between the magnet 5 and the magnet slot is filled with resin to fix the magnet 5 to the magnet slot. Thereafter, the embedded magnet type motor 1 can be manufactured by assembling other components.

  The present inventors further performed the following simulation in order to obtain the optimum arrangement pattern of the elements A and B that maximize the torque and minimize the demagnetizing field.

  As a model used for the simulation, a 1/8 model of the embedded magnet type motor 1 according to the embodiment was cited, and the rotation direction was counterclockwise (the arrow direction shown in FIG. 1). JMAG-Studio was used for the magnetic field analysis and mode FRONTIER was used as the optimization tool. Further, the magnet 5 was divided into 30 elements in the same manner as described above, with 10 divisions along the long side and 3 divisions along the short side. Regarding the magnetization direction, as shown in FIG. 7, the direction perpendicular to the long side of the side surface is 0 °, and “+” is obtained when turning to the left side (counterclockwise), and “+” when turning to the right side (clockwise). -". Then, the torque and the total demagnetizing field were calculated while changing the predetermined angle α to a total of 11 levels in steps of 7.5 ° within a range of −37.5 ° to + 37.5 °.

  In addition, as a reference for comparison, element No. 1-No. The torque and the total demagnetizing field were also calculated using a model in which all 30 magnetization directions were element A. The torque at that time was 162.13 N · m, and the total demagnetizing field was 1025 kA / m.

  The optimization procedure was performed according to the following steps. In step 1, an initial model is created, and the magnetization direction is randomly assigned to all elements. In step 2, the torque and demagnetizing field sum of the initial model in step 1 are calculated by magnetic field analysis. In step 3, the analysis result for the purpose (that is, maximum torque and minimum demagnetizing field) is evaluated. In step 4, in accordance with the result of step 3, the magnetization direction for achieving the purpose is randomly redistributed. In step 5, the torque and demagnetizing field of the case produced in step 4 are calculated by magnetic field analysis. Thereafter, step 4 and step 5 are repeated.

  FIG. 8 is a map showing the relationship between the torque and the total demagnetizing field according to the simulation results. In FIG. 8, the horizontal axis represents torque, and the vertical axis represents the total demagnetizing field. The broken line L1 indicates the element No. 1-No. The torque (162.13 N · m) when all the magnetization directions of element 30 are element A, the broken line L2 indicates element no. 1-No. The total demagnetizing field (1025 kA / m) in the case where all 30 magnetization directions are element A, and the solid line L3 indicate a Pareto solution (a solution group with no superiority or inferiority).

  In FIG. 8, an area X surrounded by a broken line indicates an area “torque increase + total demagnetizing field equivalent”, and the range of the total demagnetizing field is 995 to 1025 kA / m. On the other hand, an area Y surrounded by a broken line indicates a “torque equality + demagnetizing field total increase” area, and the torque range is 162.13 to 162.35 N · m. From FIG. 8, it was found that the torque and the total demagnetizing field are contradictory, and the existence of a Pareto solution was confirmed.

  FIG. 9A shows an arrangement pattern corresponding to “torque increase + demagnetizing field total equivalent” (that is, area X). Here, the element No. 1 and no. 30 in addition to element no. Elements B are also arranged at 4, 7, 10, 13 and 27. And element no. The predetermined angles α of 1, 7, 10, 13, 27 and 30 are both + 15 ° and the element No. The predetermined angle α of 4 was + 7.5 °. The torque at this time was 162.55 N / m, and the total demagnetizing field was 1018 kA / m.

  FIG. 9B shows an arrangement pattern corresponding to “equivalent torque + total demagnetizing field reduction”. Here, the element No. 1 and no. 30 in addition to element no. Elements B are also arranged at 4, 5, 7, 10 and 13. Among these elements, element No. The predetermined angle α of 4 was + 7.5 °, while the remaining predetermined angle α was + 15 °. The torque at this time was 162.45 N / m, and the total demagnetizing field was 998 kA / m.

  FIG. 9C shows an arrangement pattern corresponding to “torque increase + demagnetizing field total decrease”. Here, the element No. 1 and no. 30 in addition to element no. Elements B are also arranged at 4, 5, 7 to 14, 16, 27 and 29. Among these elements, element No. The predetermined angle α of 1, 7, 10, 29, and 30 was + 15 °, but the remaining predetermined angle α was + 7.5 °. The torque at this time was 162.80 N / m, and the total demagnetizing field was 986 kA / m.

<Comparative example>
Further, as a comparative example, the torque and the total demagnetizing field were examined for the eight arrangement patterns (a) to (h) shown in FIG. FIG. 11 is a diagram showing each arrangement pattern.

  As shown in FIG. 10, (a) to (c) are arrangement patterns corresponding to “torque shortage + demagnetization field total increase”. (A) The torque of the arrangement pattern is 161.02 N / m. 1-No. It is smaller than the torque (162.13 N · m) when all 30 magnetization directions are element A. Further, (a) the total demagnetizing field of the arrangement pattern was 1164 kA / m. The torque of (b) was 161.60 N / m, and the total demagnetizing field was 1046 kA / m. The torque of (c) was 162.10 N / m, and the total demagnetizing field was 1047 kA / m.

  (D) and (e) are arrangement patterns corresponding to “torque shortage + demagnetization field total reduction”. The torque of (d) was 160.91 N / m, and the total demagnetizing field was 963 kA / m. The torque of (e) was 161.55 N / m, and the total demagnetizing field was 959 kA / m.

  On the other hand, (f) to (h) are arrangement patterns corresponding to “torque increase + demagnetizing field total increase”. The torque of (f) was 162.28 N / m, and the total demagnetizing field was 1031 kA / m. The torque of (g) was 162.64 N / m, and the total demagnetizing field was 1030 kA / m. The torque of (h) was 163.09 N / m, and the total demagnetizing field was 1076 kA / m.

  From the above simulation results, it was shown that 0 ° <α ≦ 15 ° is necessary in order to achieve a well-balanced increase in torque and reduction in the total demagnetizing field.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, in the above-described embodiment, the predetermined angle α of the element B arranged at the upper left corner is the same as the predetermined angle α of the element B arranged at the lower right corner, but the angles are different. May be.

DESCRIPTION OF SYMBOLS 1 Embedded magnet type motor 2 Stator 3 Rotor 4 Shaft 5 Magnet 5L Left magnet 5M Middle magnet 5R Right magnet 6 Stator iron core 7 Coil 8 Rotor core 10 Magnet assembly A Element A (1st element)
B Element B (second element)

Claims (2)

An embedded magnet type motor comprising: a stator around which a coil is wound; a rotor provided rotatably with respect to the stator; a shaft fixed to the rotor; and a plurality of rectangular parallelepiped magnets embedded in the rotor. Because
The side surface of the magnet has a long side and a short side,
The side surface is latticed by a first element having a magnetization direction perpendicular to the long side and a second element having a magnetization direction inclined at a predetermined angle counterclockwise with respect to the magnetization direction of the first element. When dividing into
The second element is arranged at each of two corners located on at least one diagonal line, and the first element is arranged at the other part,
The embedded magnet type motor, wherein the predetermined angle is greater than 0 ° and not more than 15 °. The plurality of magnets are formed in a triangular shape with the middle magnet arranged on the left and right sides of the middle magnet, the middle magnet arranged with the long side of the side face along the rotation direction of the rotor. Having a plurality of magnet sets consisting of a left magnet and a right magnet,
In the side surface of the magnet, when the second elements are respectively disposed at the upper left corner and the lower right corner,
The middle magnet is arranged so that the upper left corner is directed toward the stator, the left magnet is arranged such that the upper left corner is inclined toward the stator, and the right magnet has the upper left corner. 2. The embedded magnet type motor according to claim 1, wherein the motor is disposed so as to be inclined toward the shaft.

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