Rotor and rotary machine

Abstract

To attain reduction of a torque ripple without deteriorating characteristics of a rotary machine comprising a rotor in which flux barriers are formed.SOLUTION: In a rotor core 10 of a rotor 1, there are formed permanent magnet insertion holes 12a and 12b, which are formed in the same direction as a motor shaft 11 from one end face to the other end face of the rotor core 10, and flux barriers 14a and 14b which communicate with the magnet insertion holes 12a and 12b, extend to the side of a d axis and are formed in the same direction as the motor shaft 11 from one end face to the other end face of the rotor core 10. On an outer peripheral surface of the rotor core 10, a groove 3 is formed in the same direction as the motor shaft 11 from one end to the other end of the rotor core 10. The groove 3 is formed closer to the d axis than a tangent FB of d axis side ends of the flux barriers 14a and 14b passing a shaft center O of the motor shaft 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotor and a rotating machine. [Background technology]

[0002] In order to suppress demagnetization of the rotor, a rotor has been proposed in which a flux barrier is formed that communicates with the magnet insertion hole of the rotor core and extends from the q-axis side to the d-axis side (Patent Document 1).Also, in order to reduce torque ripple of the rotor, a rotor has been proposed in which a groove is formed on the outer peripheral surface near the magnet insertion hole on the q-axis side of the rotor core (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-38217 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-312316 Summary of the Invention [Problem to be solved by the invention]

[0004] In the rotor of Patent Document 1, the flux barrier extending toward the d-axis side causes the magnetic flux flowing through the teeth on either side of the tooth along the d-axis to be approximately the same, so the air gap magnetic flux density has harmonics, which adversely affects torque ripple.

[0005] In Patent Document 2, grooves are formed on the outer peripheral surface of the rotor core to reduce torque ripple, but no consideration has been given to the relationship between the grooves and a flux barrier extending toward the d-axis side formed in the rotor core.

[0006] In view of the above, an object of the present invention is to reduce torque ripple without deteriorating the characteristics of a rotating machine having a rotor on which a flux barrier is formed. [Means for solving the problem]

[0007] Therefore, one aspect of the present invention is a rotor having a rotor core that rotates around a rotation axis, wherein the rotor core has a permanent magnet insertion hole formed in the same direction as the rotation axis from one end face of the rotor core to the other end face, and a flux barrier that is connected to the permanent magnet insertion hole and extends toward the d-axis, from one end face of the rotor core to the other end face, and is formed in the same direction as the rotation axis, and a groove portion is formed on the outer surface of the rotor core from one end of the rotor core to the other end, in the same direction as the rotation axis, and the groove portion is formed on the d-axis side of the tangent to the d-axis side end of the flux barrier that passes through the axis of the rotation axis.

[0008] In one aspect of the present invention, in the rotor, the grooves are formed on an outer peripheral surface of the rotor core facing the stator tooth located on the d-axis and adjacent teeth on both sides.

[0009] In one aspect of the present invention, in the rotor, the ratio of the depth of the groove to the width of the groove is 0.4 or more and 1.0 or less.

[0010] In one aspect of the present invention, in the rotor, the grooves become deeper with increasing distance from the d-axis side.

[0011] In one aspect of the present invention, in the rotor, the ratio of the depth of the groove on the q-axis side to the depth on the d-axis side is greater than 1 and 10 or less.

[0012] One aspect of the present invention is a rotating machine including the rotor described above. [Effects of the Invention]

[0013] According to the present invention as described above, torque ripple can be reduced without deteriorating the characteristics of a rotating machine having a rotor on which a flux barrier is formed. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a cross-sectional view showing a part of a rotor and a part of a stator of a rotating machine according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged view showing dimensions of grooves formed in the rotor of FIG. 1 according to the first embodiment; [Figure 3] 10 shows the relationship between the ratio of torque ripple when the grooves of embodiment 1 are formed in the rotor to the torque ripple when the grooves are not formed in the rotor, and the ratio of the depth of the grooves to the width of the grooves. [Figure 4] 4A and 4B are surface magnetic flux density waveform diagrams for a rotor having grooves according to the first embodiment and a rotor having no grooves. [Figure 5] 4A and 4B are waveform diagrams of torque ripples when the grooves of the first embodiment are formed on the rotor and when the grooves are not formed on the rotor. [Figure 6] 4 is a diagram showing the degree of magnetic flux flow in the rotor and the stator of the first embodiment. [Figure 7] 10(a) is a cross-sectional view showing a part of a rotor and a part of a stator of a rotary machine according to a second embodiment of the present invention, and FIG. 10(b) is an enlarged view showing the dimensions of a groove formed in the rotor. [Figure 8] 10A and 10B are waveform diagrams of surface magnetic flux density when the rotor has the grooves of the second embodiment and when the rotor does not have the grooves. [Figure 9] 10A and 10B are waveform diagrams of torque ripples when the grooves of the second embodiment are formed on the rotor and when the grooves are not formed on the rotor. [Figure 10] The relationship between the ratio of the torque ripple when the groove of embodiment 2 is formed in the rotor to the torque ripple when the groove is not formed, and the ratio of the depth of the groove on the q-axis side to the depth of the groove on the d-axis side. [Figure 11] 10 is a diagram showing the degree of magnetic flux flow in the rotor and the stator of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] [Embodiment 1] 1 shows a cross-sectional structure perpendicular to the axial direction of a rotor 1 of a motor according to a first embodiment, which is one aspect of a rotating machine of the present invention. Only one main pole of the rotor 1 is shown in the figure, and the other main poles are omitted because they have the same configuration as the main pole.

[0017] The motor includes a rotor 1 and a stator 2 that is coaxial with and surrounds the rotor 1. The rotor 1 includes a rotor core 10 and permanent magnets 13a and 13b. The stator 2 includes a stator core 20 and a stator coil 21.

[0018] Stator core 20 has stator slots 23 formed along the outer periphery of rotor 1 at equal intervals, on which stator coils 21 wound around teeth 22 are mounted.

[0019] Rotor core 10 is a substantially cylindrical member formed by laminating silicon steel plates. Motor shaft 11 is fitted into the axial core of rotor core 10 as a rotating shaft, and motor shaft 11 is rotatably supported by bearings (not shown).

[0020] In the rotor core 10, the axis indicated by the straight line d connecting the axial center of the rotor 1 in Fig. 1 and the center of any main magnetic pole that generates magnet torque (for example, the center position between the permanent magnets 13a and 13b) is the d-axis of the dq coordinate system. The axis that is orthogonal to the d-axis in terms of electrical angle is the q-axis of the dq coordinate system.

[0021] A pair of permanent magnet insertion holes 12a, 12b are formed in the main magnetic pole of the rotor core 10 and arranged in a V shape along the circumferential direction of the rotor 1. The permanent magnet insertion holes 12a, 12b penetrate the rotor core 10 from one end face to the other end face of the rotor core 10 in the same direction as the motor shaft 11, are arranged in a V shape that is symmetrical about the d-axis of the rotor 1, and are formed at equal intervals along the circumferential direction of the rotor core 10. Elongated plate-shaped permanent magnets 13a, 13b extending along the axial direction of the rotor 1 are inserted into the permanent magnet insertion holes 12a, 12b, respectively, so that the permanent magnets 13a, 13b are arranged along the circumferential direction of the rotor core 10.

[0022] Furthermore, at the q-axis side end of permanent magnet insertion hole 12a, a flux barrier 14a is formed, which extends along the outer periphery toward the d-axis and penetrates from one end of rotor core 10 to the other in the same direction as motor shaft 11. Similarly, at the q-axis side end of permanent magnet insertion hole 12b, a flux barrier 14b is formed, which extends along the outer periphery toward the d-axis in line symmetry with flux barrier 14a about the d-axis and penetrates from one end of rotor core 10 to the other in the same direction as motor shaft 11. Flux barriers 14a and 14b are holes that release centrifugal force acting on permanent magnets 13a and 13b when rotor 1 rotates, and their circumferential lengths toward the d-axis side are changed as appropriate.

[0023] Grooves 3 are formed in the outer peripheral surface of rotor core 10 facing teeth 22 of stator 2 located on the d-axis and both adjacent teeth 22, extending from one end of rotor core 10 to the other in the same direction as motor shaft 11. The outer peripheral surface corresponds to the position surrounded by the black circle that obstructs the flow of magnetic flux indicated by the black arrow from rotor 1 to teeth 22 of stator 2 when torque is applied to rotor 1 by passing current through stator coil 21.

[0024] Groove portions 3 are formed in the same direction as motor shaft 11 from one end to the other of rotor core 10 at locations on the d-axis side of tangent line FB to ends of flux barriers 14a, 14b that pass through axis center O of motor shaft 11. In particular, groove portions 3 are arranged symmetrically about the d-axis on the surface of rotor core 10 that corresponds to the magnetic path of the magnetic flux of teeth 22 on both sides of teeth 22 through which the d-axis passes, or of any one of teeth 22. Note that if the width of flux barriers 14a, 14b from the q-axis side to the d-axis side is short, groove portions 3 may be provided not on the outer peripheral surface of rotor core 10 that faces the adjacent teeth 22 on both sides, but on the outer peripheral surface of rotor core 10 that faces the teeth 22 on both sides of the adjacent teeth 22.

[0025] The groove 3 has an inverted trapezoidal cross section, as shown in FIG. 2. The groove 3 shown in the figure has a width Wa of, for example, 1.0 mm and a depth Wb of, for example, 0.5 mm. FIG. 3 shows the relationship between the ratio of the torque ripple when the groove 3 is formed to the torque ripple when the groove 3 is not formed in the rotor 1, and the ratio Wb / Wa of the depth Wb of the groove 3 to the width Wa of the groove 3. As is clear from the results in the same figure, the ratio Wb / Wa of the groove 3 is set to 0.4 or more. As a result, the ratio H1 / H0 of the torque ripple when the groove 3 is formed (the difference H1 between the maximum and minimum values ​​of the torque waveform) to the torque ripple when the groove 3 is not formed (the difference H0 between the maximum and minimum values ​​of the torque waveform) becomes less than 1.0.

[0026] The upper limit of the depth Wb of the groove 3 is set to the distance at which the bridge portion 15 in FIG. 1 between the flux barriers 14a, 14b and the outer periphery of the rotor 1 is thinnest (width Wbr of the bridge portion 15), from the viewpoint of suppressing short-circuit magnetic flux flowing only through the rotor 1 while not unnecessarily hindering the flow of magnetic flux from the rotor 1 to the stator 2. The depth Wb of the groove 3 depends on the performance required of the rotor 1, but is set to, for example, 1.0 mm or less.

[0027] Furthermore, if the depth Wb of the groove 3 is excessively large, the current value increases relative to the target torque, adversely affecting motor efficiency and increasing copper loss. Therefore, it is advisable to limit the ratio Wb / Wa of the depth Wb of the groove 3 to the width Wa of the groove 3 to a certain numerical range. For example, limiting the ratio Wb / Wa to 0.4 or greater and 1.0 or less can suppress the impact on copper loss (efficiency) in design. In particular, based on the results in Figure 3, setting the ratio Wb / Wa to 0.4 or greater and 0.7 or less can more reliably suppress the impact. Furthermore, applying R-chamfering to the boundaries between the inner surface and the bottom and edges of the groove 3 can reduce stress concentration at these boundaries.

[0028] In the rotor 1 described above, grooves 3 are formed on the outer peripheral surface of the rotor core 10 facing the teeth 22 of the stator 2 located on the d-axis and the adjacent teeth 22 on both sides. This increases the magnetic resistance of the magnetic path of the magnetic flux on the outer peripheral surface, thereby reducing the magnetic flux flowing through the adjacent teeth 22 on both sides. As a result, as is clear from a comparison of the surface magnetic flux density waveforms when the rotor 1 has grooves 3 and when the rotor 1 does not have grooves 3, as shown in Figure 4, the harmonic components of the surface magnetic flux density waveform when the grooves 3 are not formed are reduced. Therefore, the magnetic flux density (radial direction) in the air gap between the rotor 1 and the stator 2 under no load approaches a sinusoidal wave. Therefore, as is clear from a comparison of the torque ripple (the difference between the maximum and minimum values ​​of the torque waveform) when the rotor 1 has grooves 3 and when the rotor 1 does not have grooves 3, as shown in Figure 5, the torque ripple is significantly reduced.

[0029] 1 and 6, in rotor core 10, flux barriers 14a and 14b act as air gaps, making it difficult for magnetic flux to flow. Under load (when torque is applied), magnetic flux travels through rotor core 10, avoiding flux barriers 14a and 14b, as indicated by the black arrows in FIG. 1, and transfers to stator core 20. Here, magnetic flux that passes through the ends of flux barriers 14a and 14b transfers to teeth 22 of stator 2, but grooves 3 formed on the outer peripheral surface of rotor core 10 facing teeth 22 increase the distance between rotor core 10 and teeth 22, obstructing the flow of magnetic flux. At this time, as described above, harmonics in the surface magnetic flux density waveform of the air gap between rotor core 10 and teeth 22 are reduced, resulting in a reduction in torque ripple.

[0030] As described above, the rotor 1 of this embodiment and the motor including the rotor 1 can reduce torque ripple without deteriorating the characteristics of a rotating machine including the rotor 1 on which the flux barriers 14a, 14b are formed.

[0031] If the depth Wb of the grooves 3 is too large, the cost of increased copper loss relative to the reduction in torque ripple increases. Therefore, the ratio Wb / Wa is set to 0.4 or more and 1.0 or less under the condition that the ratio H1 / H0 (the difference H1 between the maximum and minimum values ​​of the torque waveform when the grooves 3 are formed) is less than 1.0, where H0 is the difference H0 between the maximum and minimum values ​​of the torque waveform when the grooves 3 are not formed. This allows the design to suppress the impact on copper loss. In particular, by setting the ratio Wb / Wa to 0.4 or more and 0.7 or less, the effect of suppressing the impact is even more reliable.

[0032] [Embodiment 2] The grooves 3 formed in the rotor 1 of the second embodiment shown in FIG. 7 are formed so as to become deeper with increasing distance from the d-axis side.

[0033] That is, a groove portion 3 is formed on the outer surface of the rotor 1 corresponding to the magnetic path of the magnetic flux flowing through the teeth 22 on either side of the tooth 22 located on the d-axis, more specifically, on the portion of the outer surface of the rotor core 10 facing the adjacent teeth 22 on either side.

[0034] The width Wa of the groove 3 is set to be less than the width of the teeth 22. For the same purpose as in the first embodiment, the depth Wb of the groove 3 has an upper limit equal to the width Wbr of the flux barriers 14a, 14b and the bridge portion 15 of the rotor 1. The depth Wb of the groove 3 is also set to be, for example, 1.0 mm or less, as in the first embodiment.

[0035] Furthermore, the depth Wbd of the groove 3 on the d-axis side and the depth Wbq on the q-axis side are set to satisfy the relationship of the following formula (1). Wbd <Wbq …(1)

[0036] The ratio of the depth Wbq on the q-axis side of the groove 3 to the depth Wbd on the d-axis side is set to a range greater than 1 and not greater than 10. For example, if the depth Wbd on the d-axis side of the groove 3 is 0.08 mm, the depth Wbq on the q-axis side is set to be 0.8 mm or less.

[0037] As in the first embodiment, the boundaries between the inner surface and the bottom surface and the edge of the groove 3 are rounded to reduce stress concentration at the boundaries.

[0038] According to the rotor 1 described above, the depth of the grooves 3 is set to increase with increasing distance from the d-axis side of the rotor 1, so that the magnetic resistance of the magnetic path of the magnet's magnetic flux increases the farther away from the d-axis. As a result, as shown in Figure 8, the magnetic flux density (radial direction) in the air gap between the rotor 1 and stator 2 at no load approaches a sine wave, and torque ripple is reduced as shown in Figure 9. At this time, the depth Wbq of the grooves 3 on the d-axis side is sufficiently small, so the effect of narrowing the q-axis magnetic path is also sufficiently small, and there is no impact on motor efficiency. Therefore, torque ripple can be reduced without degrading motor characteristics such as motor efficiency.

[0039] FIG. 10 shows the relationship between the ratio of torque ripple when grooves 3 are formed in the rotor 1 to the torque ripple when grooves 3 are not formed, and the ratio Wbq / Wbd, which is the ratio of the depth Wbq on the q-axis side of the grooves 3 to the depth Wbd on the d-axis side of the grooves 3. Compared to a rotor 1 without grooves 3, it can be seen that satisfying Wbd≦Wbq has the effect of reducing torque ripple. In particular, the torque ripple reduction effect is greatest when Wbq / Wbd=5. (In the same figure, the torque ripple ratio was 0.85 when the ratio Wbq / Wbd=1.0, 0.63 when the ratio Wbq / Wbd=2.5, 0.59 when the ratio Wbq / Wbd=3.4, 0.55 when the ratio Wbq / Wbd=5.0, and 0.61 when the ratio Wbq / Wbd=6.3.) As is clear from the degree of magnetic flux flow in the rotor 1 and stator 2 shown in Figure 11, if the grooves 3 are too deep, there is a concern that efficiency will decrease. From the results in Figure 10, the torque ripple reduction effect is ensured when Wbq / Wbd is in the range of 1 to 10, and particularly when Wbq / Wbd is in the range of 2 to 7. [Explanation of symbols]

[0040] 1...Rotor 2... stator, 20... stator core, 21... stator coil, 22... teeth, 23... stator slot 3...Groove, Wa...Width, Wb...Depth, Wbd...Depth on d-axis side, Wbq...Depth on q-axis side 10...Rotor core 11...motor shaft, O...shaft center 12a, 12b...Permanent magnet insertion holes 13a,13b...Permanent magnet 14a, 14b...Flux barrier 15...Bridge section, Wbr...Width

Claims

1. A rotor core that rotates around a rotation axis, The rotor core is formed with a permanent magnet insertion hole that is formed from one end face of the rotor core to the other end face in the same direction as the rotation axis, and a flux barrier that is connected to the permanent magnet insertion hole, extends toward the d-axis, and is formed from one end face of the rotor core to the other end face in the same direction as the rotation axis, a groove portion is formed on the outer peripheral surface of the rotor core from one end to the other end of the rotor core in the same direction as the rotation axis, The groove is formed on the d-axis side of a tangent line of the d-axis side end of the flux barrier that passes through the axis of the rotating shaft. A rotor characterized by:

2. 2. The rotor according to claim 1, wherein the grooves are formed in the outer peripheral surface of the rotor core facing the stator tooth located on the d-axis and both adjacent teeth.

3. 2. The rotor according to claim 1, wherein the ratio of the depth of the groove to the width of the groove is equal to or greater than 0.4 and equal to or less than 1.

0.

4. 2. The rotor according to claim 1, wherein the grooves become deeper with increasing distance from the d-axis side.

5. 5. The rotor according to claim 4, wherein the ratio of the depth of the groove on the q-axis side to the depth on the d-axis side is greater than 1 and is 10 or less.

6. A rotating machine comprising the rotor according to any one of claims 1 to 5.

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