JP2017201849A - Embedded permanent magnet type synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve a problem that further miniaturization and increase in torque and efficiency are desired in the conventional art.SOLUTION: An embedded permanent magnet type synchronous motor comprises: a stator that has a plurality of teeth formed at an inner peripheral side of the stator and around which an induction coil is wound; and a rotor provided inside the stator, and that has a plurality of magnets juxtaposed in an outer circumferential direction so as to be respectively opposed to the plurality of outer peripheral magnetic body parts at the inside of the plurality of outer peripheral magnetic body parts. At least one of front end parts of the plurality of teeth and the plurality of outer peripheral magnetic body parts have a circular arc shape asymmetrical in a rotation direction so that a distance between an inner periphery of the stator and an outer periphery of the rotor at a front side in the rotation direction is shorter than a distance at a rear side in the rotation direction.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an embedded permanent magnet synchronous motor (IPM (Interior Permanent Magnet Motor)) including a stator having a three-phase field winding, a permanent magnet, and a rotor.

  In recent years, as the electrification of cars accelerates, there is a strong demand for ever smaller and more efficient onboard equipment. Among them, embedded permanent magnet synchronous motors are widely used as in-vehicle motors because of their small size, high efficiency, and excellent high-speed rotation.

  For example, Patent Document 1 discloses an embedded permanent magnet type synchronous motor according to the prior art. In the embedded permanent magnet type synchronous motor, the shape of the tooth tip of the stator is a protruding shape that expands to the left and right in order to make the gap distance uniform, and the opening of the coil slot is narrowed so that the gap The effective magnetic flux is increased by lowering the magnetic resistance. Further, the rotor often suppresses cogging by providing a notch in the salient pole portion between the magnets. Furthermore, in general, the structure of the stator and the rotor has symmetry for measures against vibration and noise.

JP 2003-088019 A

  In the prior art, further miniaturization and high torque efficiency is desired.

An embedded permanent magnet synchronous motor according to an aspect of the present disclosure is provided.
A stator having a plurality of teeth formed on the inner peripheral side of the stator and wound with an induction coil;
A rotor provided on the inner side of the stator, the rotor having a plurality of magnets juxtaposed in the outer circumferential direction so as to face the outer peripheral magnetic body portions inside the plurality of outer peripheral magnetic body portions, respectively. Embedded permanent magnet type synchronous motor with
At least one of the tip portions of the plurality of teeth and the plurality of outer peripheral magnetic body portions is such that the distance on the front side in the rotational direction between the inner periphery of the stator and the outer periphery of the rotor is the rotational direction. It has a circular arc shape that is asymmetric in the rotational direction so as to be shorter than the distance on the rear side.

  According to the present disclosure, at least one of the tip of the stator teeth and the outer peripheral magnetic body portion of the rotor has an arc shape that is asymmetric in the rotation direction, thereby increasing the difference in magnetic flux density distribution in the gap. The torque can be increased. In addition, the asymmetrical arc shape can alleviate the concentration of the magnetic flux of the stator and the rotor to a part, and the iron loss during driving can be reduced. As a result, higher torque and smaller size can be achieved as compared with the prior art, and the efficiency is greatly improved as compared with the prior art.

1 is a cross-sectional view illustrating a schematic configuration of an embedded permanent magnet synchronous motor 100 according to a first embodiment. FIG. 2 is a cross-sectional view illustrating a configuration example of a tip shape of a tooth 121 of a stator 120 of the embedded permanent magnet type synchronous motor 100 of FIG. 1. FIG. 2 is a cross-sectional view illustrating a configuration example of an outer shape of a rotor 110 of the embedded permanent magnet synchronous motor 100 of FIG. 1. 2 is a cross-sectional view showing a first positional relationship between a stator 120 and a rotor 110 in the embedded permanent magnet synchronous motor 100 of FIG. 1. FIG. FIG. 3 is a cross-sectional view showing a second positional relationship between a stator 120 and a rotor 110 in the embedded permanent magnet synchronous motor 100 of FIG. 1. It is a simulation result of the embedded permanent magnet type | mold synchronous motor 200 which concerns on the comparative example of FIG. 6, and the embedded permanent magnet type | mold synchronous motor 100 which concerns on Embodiment 1 of FIG. It is sectional drawing which shows schematic structure of the embedded permanent magnet type | mold synchronous motor 200 which concerns on a comparative example.

  Hereinafter, comparative examples and embodiments according to the present disclosure will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

(Comparison example and point of view of the present inventor)
FIG. 6 is a cross-sectional view showing a schematic configuration of an embedded permanent magnet synchronous motor 200 according to a comparative example. For convenience of illustration, only the induction coil 122 and the permanent magnets 111a and 111b are hatched, and the rotor 110 and the stator 120 are not hatched.

  In FIG. 6, the embedded permanent magnet type synchronous motor 200 is configured by arranging an IPM type rotor (field rotor) 110 inside a stator (armature stator) 120. For example, twelve 3m (m is a positive integer) teeth 121 projecting from the inner periphery of the stator 120 are formed at predetermined angular intervals, and the induction coil 122 is wound around each tooth 121 by concentrated winding. Has been. A pair of permanent magnets (for example, ferrite magnets) 111a and 111b are embedded at equal intervals in the circumferential direction in the rotor 110 that rotates in the rotation direction 10 about the rotation axis center C1, and the total is, for example, 10 poles. Permanent magnets 111a and 111b having 2n poles (n is a positive integer different from m) are formed. Here, each pair of permanent magnets 111a and 111b has a rectangular cross section, the longitudinal direction of the rectangle is parallel to the tangential direction of the outer periphery of the rotor 110, and the adjacent permanent magnets 111a and 111b have different poles. It is formed as follows.

  Note that the outer peripheral edge of the rotor 110 located between the permanent magnets 111a and 111b and the outer periphery of the rotor 110 has an arc shape (permanent magnet 111a) that protrudes outward so as to face the permanent magnets 111a and 111b. , 111b (symmetrical with respect to a radial line passing through the center in the longitudinal direction). The protrusion 115 is made of a magnetic material, and its arc shape has a radius smaller than the radius of the outer periphery of the rotor 110. Further, between the permanent magnets 111a and 111b adjacent to each other, magnetic flux barriers 112 and 113 for preventing leakage of magnetic flux and short circuit are formed by notching the rotor 110 in the thickness direction. .

  In the comparative example, a configuration example is disclosed in which the torque fluctuation is suppressed and the torque is increased and the efficiency is improved by notching the inner side of one end of the tip portion of the tooth 121 of the stator 120 to have an asymmetric structure. However, if the tip of the tooth 121 is notched as in the structure of FIG. 6, the magnetic flux path is narrowed, which increases the magnetic resistance and may increase the iron loss of the stator 120. Recently, various structural devices have been devised to improve the characteristics. However, for example, in the case of a structure in which the extension of the tip of the tooth 121 is small for high torque and the slot opening 123 between the edge portions of the adjacent teeth 121 and 121 is large, Patent Document 1 is applied. Then, there was a problem that it returned and the torque decreased.

  Based on the above problem recognition, the inventor has created a configuration shown in the following embodiment.

(Embodiment 1)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an embedded permanent magnet synchronous motor 100 according to the first embodiment. 2 is a cross-sectional view showing a configuration example of the tip shape of the tooth 121 of the stator 120 of the embedded permanent magnet synchronous motor 100 of FIG. 3 is a cross-sectional view showing an example of the configuration of the outer shape of the rotor 110 of the embedded permanent magnet synchronous motor 100 of FIG. 1-3, the same code | symbol is attached | subjected about the component similar to FIG. For convenience of illustration, only the induction coil 122 and the permanent magnets 111 a and 111 b are hatched, and the rotor 110 and the stator 120 are not hatched.

  In FIG. 1, an embedded permanent magnet type synchronous motor 100 is configured by arranging an IPM type rotor (field rotor) 110 inside a stator (armature stator) 120. For example, twelve 3m (m is a positive integer) teeth 121a and 121b (generally denoted by reference numeral 121) projecting from the inner periphery of the stator 120 are formed at predetermined angular intervals, and each tooth An induction coil 122 is wound around 121 by concentrated winding. A pair of permanent magnets 111a and 111b (generically, denoted by reference numeral 111) are equally spaced in the circumferential direction of the rotor 110 that rotates in the rotation direction 10 about the rotation axis center C1. An embedded permanent magnet 111 having 2n poles (n is a positive integer different from m), for example, 10 poles in total is formed. Here, each pair of permanent magnets 111 has a rectangular cross section, the longitudinal direction of the rectangle is parallel to the tangential direction of the outer periphery of the rotor 110, and the adjacent permanent magnets 111 have different poles. ing.

  Note that the outer peripheral edge of the rotor 110 located between the permanent magnet 111 and the outer periphery of the rotor 110 has an outer peripheral magnetic body portion 115 </ b> A that faces each permanent magnet 111. Further, between the permanent magnets 111 adjacent to each other, magnetic flux barriers 112A and 113 for preventing leakage of magnetic flux and short circuit are formed by cutting the rotor 110 in the thickness direction. Further, a slot opening 123A is formed between the edge portions of the teeth 121 and 121 adjacent to each other.

  1 is different from the embedded permanent magnet synchronous motor 200 according to the comparative example of FIG. 6 in the following points.

(Characteristic configuration 1) FIG. 6 has a tip circumference along the inner circumference of the stator 120 of FIG. 6 and is symmetrical with respect to the center line L1 (FIG. 2) in the width direction of each tooth 121 as a symmetry axis. Compared to the tip 121, the tip 121 A of the tooth 121 of the stator 120 of FIG. 1 has a tip circumference along the inner circumference of the stator 120, but the geometric center in the width direction of each tooth 121. It has a tip 121A that is asymmetric with a line (hereinafter referred to as a center line) L1 (FIG. 2) as an axis of symmetry. Specifically, the front end portion 121A according to the first embodiment is defined by using the center line L1 in FIG. 2, when divided into three parts 121Aa, 121Ab, 121Ac as shown in FIG. 2, the tip 121A on the side surface of the radial outline L2 has a part 121Aa projecting in the circumferential direction. The tip 121A is formed so that the tip 121A on the side surface of the line L2 does not have a portion protruding in the circumferential direction, that is, the tip 121A is asymmetric in the circumferential direction. Details of this will be described later with reference to FIG.

(Characteristic configuration 2) The length L13 along the radial outline L3 of the tooth 121 of the tip 121A is shorter than the length L12 along the radial outline L2 of the tooth 121 of the tip 121A. That is, the tip 121 </ b> A is formed so that the tip 121 </ b> A of the tooth 121 is closer to the front portion in the rotation direction 10 and the distance between the tooth 121 and the rotor 110 becomes smaller. Details of this will be described later with reference to FIG.

(Characteristic Configuration 3) Each protrusion 115 of the rotor 110 in FIG. 6 has an arc shape that is symmetrical in the circumferential direction. In FIG. 1, instead of the protruding portion 115, an outer peripheral magnetic body portion 115A having an arc-shaped cutout portion 116 that is asymmetric in the circumferential direction is provided. Details of this will be described later with reference to FIG.

  First, a configuration example of the tip 121A of the tooth 121 will be described in detail below with reference to FIG.

  In FIG. 2, the tip 121A of the tooth 121 is divided into three parts 121Aa, 121Ab, and 121Ac as shown in FIG. 2, using the center line L1 and the radial outlines L2 and L3 of the tooth 121 as boundaries. Think. That is, the tip 121A is composed of portions 121Aa, 121Ab, and 121Ac. The portion 121Ac has an outer shape side surface extending along the radial outer shape line L3 at the tip thereof. On the other hand, the portion 121Ab is connected to a portion 121Aa extending in the circumferential direction at the tip. That is, the tip 121A of the tooth 121 has an asymmetric shape with the center line L1 as the axis of symmetry.

  In the embodiment of FIG. 2, the portion 121Aa of the tip 121A is located on the front side in the circumferential direction, but the present disclosure is not limited thereto, and may be formed so as to be connected to the portion 121Ac on the rear side in the circumferential direction. .

  In addition, the length L13 of the tip 121A along the radial outline L3 of the tooth 121 is shorter than the length L12 of the tip 121A of the tooth 121 along the radial outline L2 of the tip 121A. Is formed. That is, the tip 121 </ b> A is formed such that the distance between the tooth 121 and the rotor 110 is small at the tip 121 </ b> A of the tooth 121 in the front portion in the rotation direction 10. In other words, the tip 121 </ b> A is formed such that the tip 121 </ b> A of the tooth 121 is closer to the front of the rotation direction 10 and the tooth 121 and the rotor 110 are closer to each other.

  In the above, the feature configuration 1, its modification example, and the feature configuration 2 have been described. However, the present disclosure may constitute only one of the feature configuration 1, its modification example, and the feature configuration 2.

  Next, a configuration example of the outer peripheral magnetic body portion 115A of the rotor 110 will be described in detail with reference to FIG.

  In FIG. 3, the outer peripheral magnetic body portion 115 </ b> A of the rotor 110 is formed at the outer peripheral edge portion of the rotor 110 corresponding to each permanent magnet 111. Here, each outer peripheral magnetic body portion 115A has a notch 116 having an arc shape that is asymmetric in the circumferential direction, and the arc shape is a center located on the outer peripheral side in the rotor 110 with respect to the rotation axis center C1. Centering on C2, it has a radius R2 that is smaller than the radius R1 of the rotor 110. In FIG. 3, the axis passing through the longitudinal center of the permanent magnet 111 from the rotation axis center C1 is d-axis, and the axis passing through the intermediate point between the rotation magnet center C1 and the adjacent permanent magnets 111a and 111b is q. Axis. The cutout portion 116 of each outer peripheral magnetic body portion 115A is formed by removing a portion of the rotor 110 surrounding the outer periphery of the rotor 110, an arc having a radius R2 around the center C2, and the q axis. The outer peripheral magnetic body portion 115A configured as described above has a notch portion on the front side in the circumferential direction of each permanent magnet 111 and the magnetic flux path is widened. It is preferable to make it larger than the magnetic flux barrier 113 on the side. Specifically, the magnetic flux barrier 112 </ b> A is longer in the radial direction than the magnetic flux barrier 113.

  According to the embedded permanent magnet synchronous motor 100 according to the first embodiment configured as described above, the following effects can be obtained.

  4A is a cross-sectional view showing a first positional relationship between the stator 120 and the rotor 110 in the embedded permanent magnet synchronous motor 100 of FIG. 4B is a cross-sectional view showing a second positional relationship between the stator 120 and the rotor 110 in the embedded permanent magnet synchronous motor 100 of FIG. 4A shows a case where the permanent magnet 111a of the rotor 110 is close to the teeth 121a of the stator 120, and FIG. 4B shows a case where the permanent magnet 111a of the rotor 110 moves away from the teeth 121a of the stator 120.

  As shown in FIG. 4A, when the permanent magnet 111a approaches the tooth 121a, the magnetic flux emitted from the permanent magnet 111a advances in the rotation direction 10 in the gap between the stator 120 and the rotor 110, and the rotation direction 10 In order to reach the tooth 121a located on the front side, a stress in the rotational direction 10 is generated. Therefore, the tip 121A of the tooth 121a has no protrusion on the rear side in the rotation direction 10 (note that the front side has the portion 121Aa in FIG. 2), and is within the gap between the stator 120 and the rotor 110. Since the difference in magnetic flux density increases, the stress in the rotational direction 10 increases, resulting in an increase in torque. At the same time, since there is no notch on the front side in the rotational direction 10 of the permanent magnet 111a and the gap is narrow, the magnetic flux lines coming out of the permanent magnet 111a easily reach the teeth 121a. Then, since the effective magnetic flux increases, the torque further increases.

  On the other hand, as shown in FIG. 4B, when the permanent magnet 111 a of the rotor 110 moves away from the teeth 121 a, the magnetic flux generated from the permanent magnet 111 a has two traveling directions on the front side and the rear side in the rotation direction 10. Divided into The magnetic flux on the front side travels in the rotation direction 10 through the gap between the stator 120 and the rotor 110 and travels toward the teeth 121b located on the front side in the rotation direction 10, and thus generates stress in the rotation direction 10. However, the magnetic flux on the rear side in the rotational direction 10 travels in the direction opposite to the rotational direction 10 in the gap between the stator 120 and the rotor 110 and travels toward the teeth 121a located on the rear side in the rotational direction 10. Therefore, stress in the direction opposite to the rotation direction 10 is generated. Therefore, the tip 121A of the tooth 121a has no protrusion on the rear side in the rotational direction 10, and the range in which the magnetic flux travels in the reverse direction is narrowed. Therefore, the stress in the direction opposite to the rotational direction 10 is reduced, resulting in torque. Reduction is suppressed. At the same time, since there is a notch 116a on the rear side in the rotation direction 10 on the permanent magnet 111a and the gap is wide, the magnetic flux lines coming out of the magnet do not easily reach the stator 120. Then, since the effective magnetic flux is small, torque reduction is further suppressed.

  FIG. 5 is a simulation result of the embedded permanent magnet synchronous motor 200 according to the comparative example of FIG. 6 and the embedded permanent magnet synchronous motor 100 according to the first embodiment of FIG. In FIG. 5, the horizontal axis represents the rotation angle (deg), and the vertical axis represents the torque normalized with the torque average value of the comparative example as 1 with respect to the rotation angle.

  As can be seen from FIG. 5, in the torque that repeatedly increases and decreases according to the rotational position of the rotor 110, the maximum point is higher than the comparative example, and the minimum point is raised. Thus, it can be seen that the amount of lift at the minimum point is larger than the increase at the maximum point, so that cogging is suppressed.

  Moreover, according to the structure shown in Embodiment 1, since there is no part with high magnetic resistance in the rear side of the rotation direction 10 of the front-end | tip part 121A of the tooth | gear 121a where magnetic flux concentrates at the time of a drive, an iron loss can be reduced. Further, in the outer peripheral magnetic body portion 115A of the permanent magnet 111 where the magnetic flux concentrates during driving, the area on the side where the notched portion 116 is not present is wide, so that the magnetic flux concentration is alleviated and iron loss can be reduced. Since the iron loss during driving is reduced with respect to the same magnetic flux input, the efficiency of the electric motor 100 is increased. Assuming the electric motor 100 that can tolerate the same iron loss amount, the iron loss amount in the same volume is reduced, so that the size can be reduced.

  As described above, according to the present embodiment, the distance between the rotor 110 and the stator 120 on the front side in the rotational direction 10 is such that the distance between the rotor 110 and the stator 120 on the rear side in the rotational direction 10 is By making the stator 120 and / or the rotor 110 asymmetric so as to be shorter than the distance between them, the difference in the magnetic flux density distribution in the gap increases, so that the torque can be increased. In addition, the asymmetrical shape can alleviate the concentration of the magnetic fluxes of the stator 120 and the rotor 110 to a part, thereby reducing iron loss during driving. As a result, the torque can be increased and the size can be reduced, and the efficiency is improved.

  In the above embodiment, the permanent magnets 111, 111a, and 111b are used. However, the present disclosure is not limited to this, and a magnet may be used.

Summary of embodiments.
The embedded permanent magnet synchronous motor according to the first aspect of the present disclosure is:
A stator having a plurality of teeth formed on the inner peripheral side of the stator and wound with an induction coil;
A rotor provided on the inner side of the stator, the rotor having a plurality of magnets juxtaposed in the outer circumferential direction so as to face the outer peripheral magnetic body portions inside the plurality of outer peripheral magnetic body portions, respectively. Embedded permanent magnet type synchronous motor with
At least one of the tip portions of the plurality of teeth and the plurality of outer peripheral magnetic body portions is such that the distance on the front side in the rotational direction between the inner periphery of the stator and the outer periphery of the rotor is the rotational direction. It has an arc shape that is asymmetric in the rotational direction so as to be shorter than the distance on the rear side.

  The embedded permanent magnet synchronous motor according to the second aspect of the present disclosure is the embedded permanent magnet synchronous motor according to the first aspect, wherein the tip ends of the plurality of teeth are radially outer side surfaces on the rear side in the rotational direction. And a portion protruding in the rotational direction from the radially outer side surface on the front side in the rotational direction.

  The embedded permanent magnet type synchronous motor according to a third aspect of the present disclosure is the embedded permanent magnet type synchronous motor according to the first or second aspect, wherein tip ends of the plurality of teeth are forward in the rotation direction of the teeth. The length of the radial outer side surface on the side is longer than the length of the radial outer side surface on the rear side in the rotational direction of the tooth.

  The embedded permanent magnet synchronous motor according to a fourth aspect of the present disclosure is the embedded permanent magnet synchronous motor according to any one of the first to third aspects, wherein the plurality of outer peripheral magnetic body portions are respectively And a notch having an arc shape having a radius shorter than the radius of the rotor.

  The embedded permanent magnet type synchronous motor according to a fifth aspect of the present disclosure is the embedded permanent magnet type synchronous motor according to the fourth aspect, wherein the notch portion includes an outer periphery of the rotor and the magnets adjacent to each other. It is comprised by removing the area | region of the outer periphery magnetic body part enclosed by q axis | shaft which is a radial direction centerline between these, and the circular arc of each said outer periphery magnetic body part.

An embedded permanent magnet synchronous motor according to a sixth aspect of the present disclosure is the embedded permanent magnet synchronous motor according to the fourth or fifth aspect, wherein the rotor is between the magnets adjacent to each other. A plurality of magnetic flux barriers disposed at both ends of each magnet;
In the plurality of magnetic flux barriers, in each of the magnets, the circumferential length of the magnetic flux barrier on the front side in the rotational direction is longer than the circumferential length of the magnetic flux barrier on the rear side in the rotational direction.

  The electric motor of the present disclosure can be used for, for example, a vehicle electric motor.

100 ... electric motor,
110 ... rotor,
111, 111a, 111b ... magnets,
112A, 113 ... Magnetic flux barrier,
115A ... outer peripheral magnetic body part,
116a, 116b ... notch,
120 ... Stator,
121, 121a, 121b ... teeth,
121A ... the tip of the tooth,
121Aa, 121Ab, 121Ac ... the tip of the tooth,
122: Induction coil.

Claims (6)

A stator having a plurality of teeth formed on the inner peripheral side of the stator and wound with an induction coil;
A rotor provided on the inner side of the stator, the rotor having a plurality of magnets juxtaposed in the outer circumferential direction so as to face the outer peripheral magnetic body portions inside the plurality of outer peripheral magnetic body portions, respectively. Embedded permanent magnet type synchronous motor with
At least one of the tip portions of the plurality of teeth and the plurality of outer peripheral magnetic body portions is such that the distance on the front side in the rotational direction between the inner periphery of the stator and the outer periphery of the rotor is the rotational direction. It has a circular arc shape that is asymmetric in the rotational direction so as to be shorter than the distance on the rear side,
Embedded permanent magnet synchronous motor. The tip portions of the plurality of teeth are arranged along the radially outer side surface on the rear side in the rotational direction, and have a portion protruding in the rotational direction from the radially outer side surface on the front side in the rotational direction. The embedded permanent magnet type synchronous motor according to claim 1. The front ends of the plurality of teeth have a length of a radial outer side surface on the front side in the rotation direction of the teeth longer than a length of a radial outer side surface on the rear side in the rotation direction of the teeth,
The embedded permanent magnet synchronous motor according to claim 1 or 2. Each of the plurality of outer peripheral magnetic body portions includes a notch portion having an arc shape having a radius shorter than the radius of the rotor.
The embedded permanent magnet synchronous motor according to any one of claims 1 to 3. The notch portion is a region of the outer peripheral magnetic body portion surrounded by the outer periphery of the rotor, the q axis that is a radial center line between the adjacent magnets, and the arc of each outer peripheral magnetic body portion. Configured by removing the
The embedded permanent magnet type synchronous motor according to claim 4. The rotor includes a plurality of magnetic flux barriers disposed between the magnets adjacent to each other and at both ends of the magnets,
In each of the magnets, the circumferential length of the magnetic flux barrier on the front side in the rotational direction is longer than the circumferential length of the magnetic flux barrier on the rear side in the rotational direction.
The embedded permanent magnet synchronous motor according to claim 4 or 5.

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