Rotor structure

Abstract

To realize a rotor structure that can reduce the circulating magnetic flux of the same permanent magnet in the radially inner rotor area and increase the magnetic flux toward the stator.SOLUTION: The rotor 100 is structured so as to include a rotor yoke 101 made of a magnetic material and arranged around a rotating shaft 10, a plurality of permanent magnets 110 arranged at predetermined angular intervals within the rotor yoke 101 along the radial direction of the rotor yoke 101 and magnetized in the circumferential direction, and flux barriers 120 each formed in the radially inner region between adjacent permanent magnets 110 within the rotor yoke 101.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a structure of a rotor used in a permanent magnet synchronous motor, and particularly to a structure of a rotor used in an embedded structure permanent magnet synchronous motor.

Background Art

[0002] In the rotor of a permanent magnet synchronous motor, in order to reduce the magnetic flux circulating in the rotor without going toward the stator, it has been conventionally known to provide a space with a high magnetic resistance called a flux barrier in the rotor yoke. A rotor having this type of flux barrier is disclosed in Patent Document 1 below.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1 above, in a surface structure permanent magnet synchronous motor in which a plurality of permanent magnets are arranged in the circumferential direction, the flux barrier is used to reduce the magnetic flux circulating near the outer periphery of the rotor.

[0005] On the other hand, in the case of an embedded structure permanent magnet synchronous motor in which a plurality of permanent magnets arranged in the radial direction are embedded in the rotor, in the radially inner region of the rotor near the rotation axis, the magnetic flux circulates from the N pole to the S pole of the same permanent magnet, and there is a problem that a part of the magnetic flux from the permanent magnet does not go toward the stator.

[0006] Therefore, in the radially inner region of the rotor near the rotation axis of the embedded structure permanent magnet synchronous motor, it is desired to reduce the magnetic flux circulating in the same permanent magnet and make more magnetic flux from the permanent magnet go toward the stator.

[0007] An object of the present invention is to provide a rotor structure capable of reducing the magnetic flux circulating in the same permanent magnet in the radially inner rotor region and increasing the magnetic flux directed toward the stator. **Means for Solving the Problems**

[0008] The rotor structure according to the present invention includes a rotor yoke provided around a rotation axis and formed of a magnetic material, and a plurality of permanent magnets provided at predetermined angular intervals in the rotor yoke along the radial direction of the rotor yoke and magnetized in the circumferential direction, and flux barriers respectively formed in the radially inner regions between adjacent permanent magnets in the rotor yoke.

[0009] In the rotor structure according to the present invention, the flux barrier may be formed by a hollow hole provided in the rotor yoke.

[0010] In the rotor structure according to the present invention, the circumferential width of the flux barrier may be formed in a first shape that becomes narrower toward the radially inner side.

[0011] In the rotor structure according to the present invention, the circumferential width of the flux barrier may be formed in a first shape that becomes narrower toward the radially inner side. Further, the flux barrier may be further formed to include a second shape that contacts the first shape toward the radially outer side, and the circumferential width of the second shape may be formed to become narrower toward the radially outer side. **Advantages of the Invention**

[0012] In the rotor structure according to the present invention, a plurality of permanent magnets magnetized in the circumferential direction are provided at predetermined angular intervals in the rotor yoke along the radial direction of the rotor yoke provided around the rotation axis, and flux barriers are respectively formed in the radially inner regions between adjacent permanent magnets in the rotor yoke. Therefore, in the radially inner rotor region close to the rotation axis, due to the presence of the flux barriers, the magnetic flux circulating in the same permanent magnet is reduced, and the magnetic flux directed from the permanent magnet toward the stator is increased.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 10

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the rotor structure of the present invention (hereinafter referred to as "the structure of rotor 100") will be described with reference to the drawings. In each figure, the same parts are denoted by the same reference numerals.

[0015] Embodiment 1. First, the structure of rotor 100 in Embodiment 1 will be described with reference to FIGS. 1 to 7.

[0016] FIG. 1 is a configuration diagram showing the structure of the rotor 100 according to Embodiment 1. FIG. 2 is an explanatory diagram showing an enlarged view of the arrangement of the permanent magnets and the flux barriers in the structure of the rotor 100 of Embodiment 1. FIGS. 3 to 7 are explanatory diagrams showing enlarged views of alternative examples of the arrangement of the permanent magnets and the flux barriers in the structure of the rotor 100 of Embodiment 1.

[0017] [Structure of Rotor 100] The rotor 100 mainly includes a rotor yoke 101, permanent magnets 110, and flux barriers 120. The rotor 100 is used as a rotor in an embedded-structure permanent magnet synchronous motor. The rotor yoke 101 is made of a magnetic material and is provided around the rotating shaft 10 of the embedded-structure permanent magnet synchronous motor. The rotor yoke 101 may be circular in shape or may have a shape with irregularities on the outer circumference according to the arrangement of the permanent magnets 110.

[0018] The permanent magnets 110 are embedded along the radial direction of the rotor yoke 101, and a plurality of them are provided at predetermined angular intervals within the rotor yoke 101. The plurality of permanent magnets 110 are magnetized in the circumferential direction so that the opposing surfaces have the same polarity. Here, the direction along the radius of the rotor yoke 101 is defined as the "radial direction", and the direction along the rotation direction of the rotor yoke 101 is defined as the "circumferential direction".

[0019] The flux barriers 120 are each formed in the radially inner region between adjacent permanent magnets 110 within the rotor yoke 101. The flux barriers 120 are formed as spaces with high magnetic resistance by hollow holes provided in the rotor yoke 101. The circumferential width of the flux barrier 120 is formed in a first shape 120a that narrows toward the radially inner side as shown in FIGS. 2 and 3. In the first embodiment, the "radial inner region" where the flux barrier 120 is formed is a region near the radial inner end of the permanent magnet 110 in the radial direction. The purpose of forming the flux barrier 120 in this region is to suppress the generation of magnetic flux circulating from the N pole to the S pole of the same permanent magnet 110 near the radial inner end of the permanent magnet 110. For this reason, the radial inner end of the flux barrier 120 may approach the rotation axis 10 closer than the inner end of the permanent magnet 110. A rotor yoke 101 with a predetermined width is configured to exist between the circumferential end of the flux barrier 120 and the circumferential end of the permanent magnet 110. Here, the predetermined width refers to the width necessary to maintain the mechanical strength of the rotor 100. The first shape 120a whose circumferential width narrows toward the radial inner side matches the shape of the rotor yoke 101 formed between adjacent permanent magnets 110, and the predetermined width for maintaining the above-described mechanical strength can be easily realized.

[0020] As shown in FIGS. 4 to 7, the circumferential width of the flux barrier 120 may be further formed to include a second shape 120b that contacts the first shape 120a toward the radial outer side. In this case, the circumferential width of the second shape 120b is formed to narrow toward the radial outer side.

[0021] The first shape 120a and the second shape 120b may be shapes having symmetry as shown in FIGS. 4 and 5, or may be shapes having no symmetry as shown in FIGS. 6 and 7. Also, in the flux barrier 120 of FIGS. 4 to 7, if the conditions for the circumferential width of the first shape 120a and the second shape 120b are satisfied, it is possible to change to various shapes other than those shown.

[0022] [Explanation of Magnetic Flux] Next, the magnetic flux in the rotor yoke 101A without a flux barrier as a comparative example and the magnetic flux in the rotor yoke 101 having the flux barrier 120 of the first embodiment will be described with reference to FIGS. 8 to 10. FIG. 8 is an explanatory diagram schematically showing the magnetic flux in the comparative example. FIG. 9 is an explanatory diagram schematically showing the magnetic flux in Embodiment 1. FIG. 10 is an explanatory diagram schematically showing the magnetic flux in another example of Embodiment 1. In FIGS. 8 to 10, the line thickness of the magnetic flux 200 from the N poles of two opposing permanent magnets 110 (hereinafter referred to as effective magnetic flux) and the magnetic flux 210 circulating from the N pole to the S pole of the same permanent magnet (hereinafter referred to as circulating magnetic flux) schematically represents the strength of the magnetic flux. When the rotating shaft 10 is a magnetic material, the circulating magnetic flux 210 circulating from the N pole to the S pole of the same permanent magnet 110 also passes through the rotating shaft 10, but in FIGS. 8 to 10, it is shown as passing only within the rotor 100.

[0023] · Comparative example: Hereinafter, the magnetic flux in the comparative example will be described with reference to FIG. 8. In the rotor yoke 101A shown in FIG. 8, the effective magnetic flux 200 from the N poles of two opposing permanent magnets 110 is directed from the rotor yoke 101A toward a stator (not shown). This effective magnetic flux 200 passes through the stator and the stator coil (not shown) and returns to the S pole of the permanent magnet 110.

[0024] On the other hand, in the radially inner region of the rotor yoke 101A, a circulating magnetic flux 210 circulating from the N pole to the S pole of the same permanent magnet is generated. That is, a problem has occurred in that the effective magnetic flux 200 from the permanent magnet 110 toward the stator is reduced by generating the circulating magnetic flux 210 (see the thin-line effective magnetic flux 200).

[0025] · Embodiment 1(1): Hereinafter, the magnetic flux in Embodiment 1 will be described with reference to FIG. 9. In the rotor yoke 101 shown in FIG. 9, the effective magnetic flux 200 from the N poles of two opposing permanent magnets 110 is directed from the rotor yoke 101A toward a stator (not shown). This effective magnetic flux 200 passes through the stator and the stator coil (not shown) and returns to the S pole of the permanent magnet 110.

[0026] On one hand, in the radially inner region of the rotor yoke 101, a circulating magnetic flux 210 that circulates from the N pole to the S pole of the same permanent magnet is generated through the region of the rotor yoke 101 in the gap between the permanent magnet 110 and the flux barrier 120. In Embodiment 1, in the radially inner rotor region close to the rotation axis 10, the circulating magnetic flux 210 passes through a path with a predetermined width narrowed by the flux barrier 120 (see the thin-line circulating magnetic flux 210). As a result, the circulating magnetic flux 210 in the same permanent magnet 110 is reduced, and the effective magnetic flux 200 from the permanent magnet 110 toward a stator (not shown) increases.

[0027] · Embodiment 1(2): Hereinafter, the magnetic flux in another example of Embodiment 1 will be described with reference to FIG. 10. In the rotor yoke 101 shown in FIG. 10, the effective magnetic flux 200 from the N poles of two opposing permanent magnets 110 is directed from the rotor yoke 101A toward a stator (not shown). This effective magnetic flux 200 passes through the stator (not shown) and the stator coil and returns to the S pole of the permanent magnet 110.

[0028] On one hand, in the radially inner region of the rotor yoke 101, a circulating magnetic flux 210 that circulates from the N pole to the S pole of the same permanent magnet is generated through the region of the rotor yoke 101 in the gap between the permanent magnet 110 and the flux barrier 120. In the case of FIG. 10, in the radially inner rotor region close to the rotation axis 10, the path of the circulating magnetic flux 210 is narrowed by the flux barrier 120 of the first shape 120a, and the circulating magnetic flux 210 in the same permanent magnet 110 is reduced. Further, the effective magnetic flux 200 is rectified toward the stator (not shown) by the flux barrier 120 of the second shape 120b. As a result, the circulating magnetic flux 210 in the same permanent magnet 110 is reduced, and the effective magnetic flux 200 from the permanent magnet 110 toward a stator (not shown) increases.

[0029] [Effects Obtained by Embodiment 1] The structure of the rotor 100 according to Embodiment 1 includes a rotor yoke 101 provided around the rotation axis 10 and made of a magnetic material, and a plurality of permanent magnets 110 provided at predetermined angular intervals in the rotor yoke 101 along the radial direction of the rotor yoke 101 and magnetized in the circumferential direction. The structure also includes flux barriers 120 each formed in the radially inner region between adjacent permanent magnets 110 in the rotor yoke 101. Therefore, in the radially inner region of the rotor 100, the path of the circulating magnetic flux 210 is narrowed by the flux barrier 120, so that the circulating magnetic flux 210 in the same permanent magnet 110 is reduced and the effective magnetic flux 200 from the permanent magnet 110 toward the stator increases.

[0030] In the structure of the rotor 100 according to Embodiment 1, the flux barrier 120 is formed as a space with high magnetic resistance by a hollow hole provided in the rotor yoke 101. Also, by making the flux barrier 120 a hollow hole, the moment of inertia can be reduced.

[0031] In the structure of the rotor 100 according to Embodiment 1, the circumferential width of the flux barrier 120 is formed in a first shape 120a that becomes narrower toward the radially inner side. Therefore, the path of the circulating magnetic flux 210 is narrowed by the flux barrier 120 having the first shape 120a, and the circulating magnetic flux 210 is reduced.

[0032] In the structure of the rotor 100 according to Embodiment 1, the flux barrier 120 is further formed to include a second shape 120b that contacts the first shape 120a toward the radially outer side, and the circumferential width of the second shape 120b is formed to become narrower toward the radially outer side. Therefore, the path of the circulating magnetic flux 210 is narrowed by the flux barrier 120 of the first shape 120a, and the circulating magnetic flux 210 is reduced. Further, the effective magnetic flux 200 is rectified toward a stator (not shown) by the flux barrier 120 of the second shape 120b. As a result, the circulating magnetic flux 210 in the same permanent magnet 110 is reduced, and the effective magnetic flux 200 from the permanent magnet 110 toward the stator (not shown) increases.

Explanation of Signs

[0033] 10 Rotation axis, 100 Rotor, 101 Rotor yoke, 110 Permanent magnet, 120 Flux barrier, 120a First shape, 120b Second shape, 200 Effective magnetic flux, 210 Circulating magnetic flux.

Claims

1. A rotor yoke (101) provided around a rotating shaft (10) and composed of a magnetic material, and a plurality of permanent magnets (110) provided in the rotor yoke (101) at predetermined angular intervals along the radial direction of the rotor yoke (101) and magnetized in the circumferential direction; flux barriers (120) respectively formed in the radially inner regions between the adjacent permanent magnets (110) within the rotor yoke (101); A rotor structure comprising the above components.

2. The flux barrier (120) is formed by a hollow hole provided in the rotor yoke (101), The rotor structure according to Claim 1.

3. The circumferential width of the flux barrier (120) is formed in a first shape (120a) that becomes narrower toward the radially inner side, The rotor structure according to Claim 1.

4. The flux barrier (120) is further formed to include a second shape (120b) that contacts the first shape (120a) toward the radially outer side, The circumferential width of the second shape (120b) becomes narrower toward the radially outer side, The rotor structure according to Claim 3.

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