JP2008220053A - Electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor in which a torque ripple of a specified order can be reduced, and accompanied by this, a specified harmonic component of motor noise can be also reduced. <P>SOLUTION: The motor 1 comprises a stator 100 having a plurality of winding phases 110U, 110V and 110W, a rotor 10 having an external periphery facing the stator 100, and a groove formed at the external periphery of the rotor 10. In the groove, a virtual straight line 12 connecting a bottom point having the deepest depth from the surface of the external periphery and the center of the rotor forms an electric angle of not smaller than 6° and not larger than 22° with respect to a center line 11 of a magnetic pole nearest to the bottom point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor.

  Generally, in an electric motor mounted on a vehicle, it is required to reduce torque ripple. This torque ripple indicates the variation of the output torque as a percentage of the average torque, and it is generally known that the greater the torque ripple, the greater the vibration and noise in the motor.

An example of an electric motor in which the torque ripple is reduced is an electric motor described in Japanese Patent Application Laid-Open No. 2004-329856.
Japanese Patent Laid-Open No. 2004-328956 JP 2000-295805 A Japanese Patent Laid-Open No. 7-336917 Japanese Patent Laid-Open No. 11-164501 JP 2001-145284 A JP-A-2005-261024 Japanese Patent Laying-Open No. 2005-261081 JP 2006-50791 A JP 2002-223538 A

  However, the above-described conventional electric motor pays attention to the entire torque ripple, and does not describe any technique for reducing the torque ripple by paying attention to the torque ripple of a specific order.

  In particular, the above prior art does not pay attention to the correlation between each order of torque ripple and the high-frequency component of noise generated in the motor.

  For this reason, in the conventional electric motor, although torque ripple is reduced, it is not clear which order torque ripple component is reduced, and which harmonic component of motor noise is reduced. Not.

  As a result, in conventional motors, it is not possible to selectively reduce specific harmonic components and torque ripples of a specific order among motor noises, improving the characteristics of the motor efficiently. There was a problem that I could not.

  The present invention has been made in view of the problems as described above, and can reduce torque ripple of a specific order, and accordingly, can reduce specific harmonic components of motor noise. An object of the present invention is to provide an electric motor in which the characteristics of the electric motor are efficiently improved.

  An electric motor according to the present invention is formed by distributed winding, a stator having a plurality of winding phases, a rotor having a plurality of magnetic poles and having an outer periphery facing the stator, and an outer periphery of the rotor. And a groove portion. The virtual straight line connecting the bottom point having the deepest depth from the outer peripheral surface and the center of the rotor in the groove portion is not less than 6 degrees and not more than 22 degrees with respect to the center line of the magnetic pole closest to the bottom point. Make an electrical angle.

  Preferably, the virtual straight line has an electrical angle of 6 degrees to 16 degrees with respect to the center line.

  Preferably, the virtual straight line has an electrical angle of 6 degrees to 12 degrees with respect to the center line.

  Preferably, the groove part includes a first groove part and a second groove part provided at positions symmetrical with respect to the center line. Preferably, the groove is provided for each center line of each magnetic pole.

  According to the electric motor of the present invention, it is possible to reduce a component for a specific order of torque ripple.

  The electric motor according to the present embodiment will be described with reference to FIGS. In addition, about the same structure or an equivalent structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  FIG. 1 is a cross-sectional view of a rotating electrical machine (electric motor) 1 according to the present embodiment. FIG. 2 is an enlarged view in which a portion indicated by II in FIG. 1 is enlarged.

  As shown in FIGS. 1 and 2, the rotating electrical machine 1 according to the first embodiment includes a U-phase coil 110 </ b> U as a plurality of winding phases formed by distributed winding, a V-phase coil 110 </ b> V, and a W-phase. A stator 100 having a coil 110 </ b> W and a rotor 10 having a permanent magnet 30 as a plurality of magnetic poles and having an outer peripheral surface (outer periphery) 13 facing the stator 100 are provided.

  The stator 100 has an annular core body 103, and is configured, for example, by laminating a plurality of magnetic steel plates. A plurality of stator teeth 101 projecting inward in the radial direction is formed on the inner peripheral surface of the core body 103. Slot portions (concave portions) 102 are formed between the stator teeth 101, and each slot portion 102 opens toward the inner peripheral side of the core body 103.

  Stator teeth 101 are wound with a U-phase coil 110U, a V-phase coil 110V, and a W-phase coil 110W as winding phases by distributed winding. U-phase coil 110U is located closest to the outer peripheral side of core body 103, and V-phase coil 110V is located radially inward from U-phase coil 110U. And W phase coil 110W is located in the diameter direction inner side to this V phase coil 110V.

  In the example shown in FIG. 1, each coil is wound directly around the stator teeth 101. However, for example, each coil may be mounted using an insulator.

  AC power having a phase shift is supplied to each U-phase coil 110U, V-phase coil 110V, and W-phase coil 110W wound in this manner. Thereby, the magnetic flux which passes each coil 110U, 110V, 110W generate | occur | produces.

  The rotor 10 includes a cylindrical core body 20 formed by laminating electromagnetic steel plates made of iron or iron metal.

  The core body 20 is formed with a plurality of magnet housing portions 20 </ b> A to 20 </ b> H that are formed at intervals in the circumferential direction of the core body 20 and house the permanent magnet 30.

  Here, the magnet housing portion 20 </ b> A has a pair of holes 20 </ b> A <b> 1 and 20 </ b> A, and the holes 20 </ b> A <b> 1 and 20 </ b> A <b> 2 are slightly separated in the circumferential direction of the core body 20. And the permanent magnet 30 is accommodated in this hole 20A1, 20A2. A gap 40 is formed between the inner surface of the core body 20 that defines the holes 20 </ b> A <b> 1 and 20 </ b> A <b> 2 and the permanent magnet 30. The gap 40 is located at both ends of the permanent magnet 30.

  Of the surface of the permanent magnet 30 accommodated in the hole portion 20A1, the outer peripheral surface of the core body 20 among the magnetism on the outer peripheral surface side of the core body 20 and the surface of the permanent magnet 30 accommodated in the hole portion 20A2. The surface side magnetism is the same.

  The other magnet housing portions 20B to 20H also have a pair of holes, like the magnet housing portion 20A, and the permanent magnets 30 are housed in the respective hole portions.

  Here, among the permanent magnets 30 housed in one magnet housing portion 20A to 20H, the magnetism on the outer peripheral surface side of the core body 20 and the circumferential direction of the core body 20 with respect to the magnet housing portions 20A to 20H. Of the permanent magnets 30 accommodated in the adjacent magnet accommodating portions 20A to 20H, the magnetism on the outer peripheral surface side of the core body 20 is different from each other. For this reason, among the magnets accommodated in the magnet accommodating portions 20A to 20H toward the circumferential direction of the core body 20, the magnetism on the outer peripheral surface side of the core body 20 is arranged to be alternately different.

  Here, FIG. 3 is an enlarged view showing a range where the electrical angle is 90 degrees in the rotating electrical machine 1 according to the present embodiment.

  In FIG. 3, the magnetism on the outer peripheral side of each permanent magnet 30 accommodated in each hole 20A1, 20A2 of the magnet accommodating portion 20A is the same. And the magnetism of the outer peripheral side of the permanent magnet 30 accommodated in the magnet accommodating part 20A, and the magnetism of the outer peripheral side of the permanent magnet 30 accommodated in the magnet accommodating parts 20B and 20H adjacent to the magnet accommodating part 20A Is different.

  For this reason, the center line 11 of the magnetic pole of the permanent magnet 30 housed in the magnet housing portion 20A passes through the middle of the hole portion 20A1 and the hole portion 20A2 and the center point 120 of the core body 20. Furthermore, a straight line 112 having an electrical angle of 90 degrees with the center line 11 is located between the magnet housing portion 20A and the magnet housing portion 20B adjacent to the magnet housing portion 20A in the circumferential direction of the core body 20. And passes through the center point 120.

  As described above, the rotor 10 includes a plurality of permanent magnets 30, and the stator 100 rotates when AC power is supplied to the coils 110 </ b> U, 110 </ b> V, and 110 </ b> W of the stator 100. The rotor 10 is fixed to a rotating shaft 130 inserted in a through hole formed in the central portion of the rotor 10, and the rotating shaft 130 is rotatably supported.

  Here, as shown in FIG. 2, a plurality of grooves (recesses) 14 are formed on the outer peripheral surface 13 of the rotor 10. The groove may have a polygonal shape such as a triangular shape or a quadrangular shape, and may have a smooth curved surface shape.

  Here, the bottom 15 of the groove portion 14 is a portion having the deepest depth from the outer peripheral surface 13 of the core body 20. That is, the bottom point 15 is a portion located on the innermost side in the radial direction of the core body 20 in the surface of the core body 20 that defines the groove portion 14.

  As shown in FIG. 2, the bottom point 15 is formed at a position where the electrical angle φ is 6 degrees or more and 22 degrees or less with respect to the magnetic pole center line 11 closest to the bottom point 15.

  Preferably, the bottom 15 is located at a position where the electrical angle φ formed by the center line 11 of the magnetic pole and the center line 11 is 6 degrees or more and 16 degrees or less. Furthermore, it is preferably 6 degrees or more and 12 degrees or less.

  FIG. 4 shows the torque ripple of the rotating electrical machine according to the present embodiment in which the electrical angle φ between the bottom point 15 and the center line 11 is 6 degrees or more and 22 degrees or less by a solid line. It is the graph which showed the torque ripple of the rotary electric machine of the comparative example by which electrical angle (phi) was 40 degrees or more and 44 degrees or less with the broken line.

  FIG. 5 shows a comparison between the torque ripple 24th order component and the torque ripple 48th order component by Fourier-transforming the waveforms of the torque ripples of the rotary electrical machine 1 according to the present embodiment and the rotating electrical machine of the comparative example. It is a graph to do. In FIG. 5, the vertical axis indicates the magnitude of the torque ripple 24-order component, and the horizontal axis indicates the order of torque ripple. In FIG. 5, the comparative example is a graph indicated by oblique lines, and the rotating electrical machine 1 according to the present embodiment is indicated by the other graph.

  Here, the order of the torque ripple corresponds to the cogging torque generated during one rotation of the rotor 10, and is the number of magnetic poles of the rotor 10 and the number of slot portions 102 (number of stator teeth 101). Shown in least common multiple.

  Here, in the rotating electrical machine 1 according to the present embodiment, the number of magnetic poles is 8, a three-phase coil, and the number of slot portions (number of stator teeth) is 48.

  In general, in such a rotating electrical machine of a three-phase 8-pole motor, the quality determination of the harmonic component of the motor noise is made by the 8th, 24th, and 48th orders.

  The motor noise 8th order component corresponds to the torque ripple 8th order component, and the motor noise 24th order component corresponds to the torque ripple 24th order component. Furthermore, the motor noise 48th order component corresponds to the torque ripple 48th order component.

  As can be seen from FIG. 5, the magnitude of the torque ripple 24th order component of the rotating electrical machine 1 according to the present embodiment is smaller than the torque ripple 24th order component of the rotating electrical machine of the comparative example. For this reason, it turns out that the rotary electric machine 1 which concerns on this Embodiment can aim at reduction of the 24th-order component of a motor noise rather than the rotary electric machine of a comparative example.

  FIG. 6 is a graph showing torque ripple 24th order components of the torque ripple of the rotating electrical machine for various electrical angles φ. In FIG. 6, the vertical axis represents the torque ripple 24-order component, and the horizontal axis represents the electrical angle between the bottom 15 of the groove 14 and the center line 11. As shown in FIG. 6, it can be seen that the 24th-order component of torque ripple is reduced when the electrical angle φ is in the range of 6 degrees to 22 degrees (the range indicated by φ1 in the figure).

  Here, the torque ripple 24th order component of the rotating electrical machine according to the comparative example is in a range indicated by φ4 in the drawing. Thus, it turns out that the torque ripple 24th order component of the rotary electric machine 1 which concerns on this Embodiment is reduced rather than the torque ripple 24th order component of the rotary electric machine of the said comparative example.

  Here, as shown in FIG. 6, it can be seen that in the range where the electrical angle φ is 6 degrees or more and 16 degrees or less (the range indicated by φ2 in the figure), the torque ripple 24th order component is particularly reduced.

  The torque ripple 24th order component corresponds to the motor noise 24th order component calculated by Fourier transforming the motor noise generated in the rotating electrical machine. For this reason, in the rotating electrical machine 1 according to the present embodiment, it is possible to reduce motor noise 24th order components. Thus, according to the rotating electrical machine 1 according to the present embodiment, the motor noise 24th order component of the harmonic component can be selectively reduced among the motor noise.

  FIG. 7 is a graph showing torque ripples of each rotating electrical machine by setting various electrical angles φ between a straight line (virtual straight line) 12 passing through the bottom 15 and the center point 120 of the groove 14 and the center line 11 of the magnetic pole. is there. In FIG. 7, the vertical axis represents the torque ripple, and the horizontal axis represents the electrical angle between the bottom 15 of the groove 14 and the center line 11 of the magnetic pole.

  Further, FIG. 8 is a graph showing a torque ripple 48th order component of each rotating electrical machine with various electrical angles φ set. In FIG. 8, the vertical axis represents the 48th-order component of torque ripple, and the horizontal axis represents the electrical angle between the straight line 12 and the center line 11.

  Here, as shown in FIG. 7, it can be seen that the torque ripple is sufficiently reduced when the electrical angle φ is in the range of 6 degrees to 12 degrees (the range indicated by φ3 in the figure). Furthermore, as shown in FIG. 8, it can be seen that the 48th-order component of the torque ripple is sufficiently reduced when the electrical angle φ is in the range of 6 degrees to 12 degrees (range indicated by φ3 in the figure). For this reason, it turns out that it is preferable to set electrical angle (phi) 6 to 12 degree | times.

  In FIG. 7, the rotating electrical machine according to the comparative example is in a range indicated by an electrical angle φ4 in the drawing. For this reason, the position of the bottom point 15 of the groove portion 14 is within the range where the electrical angle φ is 7 degrees or more and 8.2 degrees or less with respect to the magnetic pole center line 11 (the range indicated by φ5 in the figure). The torque ripple of the rotating electric machine is reduced. For this reason, also in the rotating electrical machine 1 according to the present embodiment, it is preferable that the position of the bottom point 15 of the groove portion 14 is 7 degrees or more and 8.2 degrees or less with respect to the center line 11 of the magnetic pole. I understand that.

  Here, as shown in FIG. 3, the groove portions 14 are respectively provided at positions symmetrical with respect to the center line 11 of the magnetic pole. Further, as shown in FIG. 1, a groove portion 14 is provided for each of the magnetic pole centerlines 11 for each pair of permanent magnets 30 accommodated in the magnet accommodating portions 20 </ b> A to 20 </ b> H.

  Although the embodiment of the present invention has been described above, it should be considered that the embodiment disclosed this time is illustrative and not restrictive in all respects. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. Furthermore, the above numerical values are examples, and are not limited to the above numerical values and ranges.

  The present invention can be used for an electric motor, and is particularly suitable for reducing torque ripple 24th order.

It is sectional drawing of the rotary electric machine (electric motor) which concerns on this Embodiment. It is the enlarged view to which the part shown by II in FIG. 1 was expanded. In the rotary electric machine which concerns on this Embodiment, it is an enlarged view which shows the range from which an electrical angle becomes 90 degree | times. The torque ripple of the rotating electrical machine according to the present embodiment in which the electrical angle φ between the bottom and the center line is 6 degrees or more and 22 degrees or less is shown by a solid line, and the electrical angle φ between the bottom and the center line is 40 degrees or more and 44 degrees or less. 5 is a graph showing a torque ripple of a rotating electrical machine of a comparative example indicated by a broken line. It is a graph which compares the torque ripple 24th order component and the torque ripple 48th order component by Fourier-transforming the waveform of the torque ripple of the rotary electric machine which concerns on this Embodiment, and the rotary electric machine of a comparative example, respectively. It is a graph which shows the torque ripple 24th order component of the torque ripple of a rotary electric machine about each setting various electrical angles (phi). It is a graph which shows the torque ripple of each rotary electric machine by setting various electrical angles (phi). It is a graph which shows the torque ripple 48th-order component of the torque ripple of each rotary electric machine by setting various electrical angles φ.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Rotating electrical machine, 10 Rotor, 11 Center line, 12 Straight line, 13 Outer peripheral surface, 14 Groove part, 15 Bottom point, 20 Core body, 20A, 20B Magnet accommodating part, 30 Permanent magnet, 40 Crevice part, 130 Rotating shaft, φ Electrical angle.

Claims (5)

A stator having a plurality of winding phases formed by distributed winding;
A rotor having a plurality of magnetic poles and having an outer periphery facing the stator;
A groove formed on the outer periphery of the rotor,
An imaginary straight line connecting the bottom point having the deepest depth from the outer peripheral surface of the groove and the center of the rotor is 6 degrees or more and 22 degrees with respect to the center line of the magnetic pole closest to the bottom point. An electric motor with the following electrical angle.   The electric motor according to claim 1, wherein the virtual straight line has an electrical angle of 6 degrees or more and 16 degrees or less with respect to the center line.   The electric motor according to claim 1, wherein the virtual straight line has an electrical angle of 6 degrees or more and 12 degrees or less with respect to the center line.   4. The electric motor according to claim 1, wherein the groove portion includes a first groove portion and a second groove portion provided at positions symmetrical with respect to the center line. 5.   The electric motor according to claim 1, wherein the groove is provided for each of the magnetic poles.

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