JP2018085877A - Rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary electric machine capable of suppressing cogging torque and torque ripple without decreasing a salient pole ratio.SOLUTION: A rotary electric machine 1 includes a stator 10 in which a plurality of slots 13 in which an armature winding 14 is arranged are formed, and a rotor 20 in which a plurality of permanent magnets 23A, 23B are buried in a rotor core 21. The rotor 20 has magnetic pole sections 24 formed by the permanent magnets 23A, 23B arranged in a V-shape expanding toward the stator side. The permanent magnets 23A, 23B are arranged such that the polarities of the magnetic pole sections 24 adjacent in the circumferential direction of the rotor 20 are opposite in polarity, and in an outer peripheral surface 20a of the rotor 20 in which the magnetic pole section 24 having the N magnetic pole is formed, grooves 30 are formed on both sides in the circumferential direction with a d-axis interposed therebetween.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rotating electrical machine.

  Conventionally, a plurality of teeth are formed radially at an interval in the circumferential direction to be an annular yoke and a winding groove, and the stator has a larger inner diameter dimension at the end of the tooth tip than the inner diameter dimension near the center of the tooth tip; 2. Description of the Related Art An electric motor including a rotor that generates a magnetic field with a permanent magnet embedded in a rotor core that is opposed to a stator with a slight gap and is rotatably supported is known (for example, Patent Documents). 1).

  In the electric motor described in Patent Document 1, the outer shape of the rotor core is a convex shape with an outer diameter with the central portion of the magnetic pole as the maximum diameter, and the shape is the number of magnetic poles, and the portion between the magnetic poles of the rotor core has the rotation axis. It has a circular arc shape at the center and a shape that is the minimum dimension of the outer shape of the rotor.

JP 2008-99418 A

  However, in the electric motor described in Patent Document 1, since the gap between the rotor core and the stator becomes wide on the q axis serving as the excitation axis, the magnetic resistance of the q axis magnetic path increases. Thereby, in the electric motor described in Patent Document 1, the reluctance torque cannot be effectively used because the salient pole ratio is reduced, and the output torque and the efficiency are reduced.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a rotating electrical machine capable of suppressing cogging torque and torque ripple without reducing the salient pole ratio.

  In order to achieve the above object, the present invention is a rotating electrical machine comprising a stator in which a plurality of slots in which armature windings are arranged and a rotor in which a plurality of permanent magnets are embedded in a rotor core, The rotor has a magnetic pole portion formed by the permanent magnets arranged in a V shape spreading toward the stator side, and the polarity of the magnetic pole portions adjacent to each other in the circumferential direction of the rotor is reversed in the permanent magnet. A configuration in which grooves are formed on both sides in the circumferential direction across the d-axis on the outer peripheral surface of the rotor, which is arranged to be polar and on which the magnetic pole portion of either the N magnetic pole or the S magnetic pole is formed Have

  ADVANTAGE OF THE INVENTION According to this invention, the rotary electric machine which can suppress a cogging torque and a torque ripple can be provided, without reducing a salient pole ratio.

FIG. 1 is a cross-sectional view of a rotating electrical machine according to an embodiment of the present invention cut along a plane perpendicular to the rotation axis. FIG. 2 is an enlarged cross-sectional view of a part of a rotating electrical machine according to an embodiment of the present invention. FIG. 3 is an enlarged view showing a groove formed in the rotor of the rotating electrical machine according to the embodiment of the present invention. FIG. 4 is a diagram showing a magnetic flux vector distribution in the rotating electrical machine according to one embodiment of the present invention. FIG. 5 is a graph showing the cogging torque in the rotating electrical machine according to one embodiment of the present invention, where (a) shows the cogging torque at the N magnetic pole formed with the groove, and (b) shows no groove formed. The cogging torque in the S magnetic pole is shown, and (c) shows the cogging torque obtained by adding the cogging torque in the N magnetic pole and the cogging torque in the S magnetic pole. FIG. 6 is a graph comparing the cogging torque in the rotating electrical machine according to one embodiment of the present invention and the cogging torque in the rotating electrical machine of the comparative example in which no groove is formed. FIG. 7 is a graph comparing the order component of cogging torque in a rotating electrical machine according to an embodiment of the present invention and the order component of cogging torque in a rotating electrical machine of a comparative example in which no groove is formed. FIG. 8 is a graph comparing the torque in the rotating electrical machine according to one embodiment of the present invention and the torque in the rotating electrical machine of the comparative example in which no groove is formed. FIG. 9 is a graph comparing the order component of torque in the rotating electrical machine according to one embodiment of the present invention and the order component of torque in the rotating electrical machine of the comparative example in which no groove is formed.

  A rotating electrical machine according to an embodiment of the present invention is a rotating electrical machine including a stator in which a plurality of slots in which armature windings are arranged is formed, and a rotor in which a plurality of permanent magnets are embedded in a rotor core. The rotor has a magnetic pole portion formed by a permanent magnet arranged in a V-shape spreading toward the stator side, and the permanent magnet has a polarity opposite to the polarity of the magnetic pole portion adjacent in the circumferential direction of the rotor. Grooves are formed on both sides in the circumferential direction across the d-axis on the outer peripheral surface of the rotor that is arranged and on which one of the magnetic pole portions of the N magnetic pole and the S magnetic pole is formed. Thereby, the rotary electric machine which concerns on one embodiment of this invention can suppress a cogging torque and a torque ripple, without reducing a salient pole ratio.

  Hereinafter, an embodiment of a rotating electrical machine according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the rotating electrical machine 1 according to the present embodiment is an interior permanent magnet synchronous motor (hereinafter referred to as IPMSM) in which a permanent magnet is embedded in a rotor. The rotating electrical machine 1 has a performance suitable for mounting on, for example, a hybrid vehicle or an electric vehicle.

  The rotating electrical machine 1 includes an annular stator 10 and a rotor 20 that is rotatably accommodated in the stator 10. The rotor 20 is fixed to a rotating shaft 2 that rotates about an axis O, and rotates integrally with the rotating shaft 2.

  The stator 10 is fixed to a motor case (not shown). The stator 10 includes an annular stator core 11 made of a magnetic material having a high magnetic permeability. The stator core 11 is formed by laminating electromagnetic steel plates in the axial direction along the axis of the rotary shaft 2.

  The stator core 11 is provided with a plurality of stator teeth 12 protruding inward in the radial direction along the circumferential direction. Between stator teeth 12 adjacent in the circumferential direction, a slot 13 that is a groove-like space is formed.

  A radial direction shows the direction orthogonal to the above-mentioned axial direction. The radially inner side indicates the side close to the rotating shaft 2 in the radial direction, and the radially outer side indicates the side far from the rotating shaft 2 in the radial direction. The circumferential direction indicates a circumferential direction around the rotation axis 2.

  In each slot 13 of the stator core 11, three-phase armature windings 14 of W phase, V phase, and U phase are arranged along the circumferential direction of the stator core 11. The W-phase, V-phase, and U-phase armature windings 14 are distributedly wound around the stator teeth 12.

  The stator 10 generates a rotating magnetic field that rotates in the circumferential direction when a three-phase alternating current is supplied to the armature winding 14. Magnetic flux generated in the stator 10 is linked to the rotor 20. Thereby, the stator 10 can rotate the rotor 20.

  The rotor 20 includes an annular rotor core 21, a plurality of permanent magnet pairs 23, and a magnetic pole part 24.

  The rotor core 21 is formed by laminating electromagnetic steel plates, which are magnetic materials with high permeability, in the axial direction along the axis of the rotary shaft 2. A plurality of slit pairs 22 are formed in the rotor core 21 along the circumferential direction of the rotor 20.

  The slit pair 22 includes a pair of slits 22A and 22B. The pair of slits 22A and 22B are provided so as to be V-shaped and widen from the radially inner side toward the radially outer side, that is, toward the stator side.

  Permanent magnets 23A and 23B are fitted into the pair of slits 22A and 22B. The pair of permanent magnets 23 </ b> A and 23 </ b> B is arranged in a V shape that widens from the radially inner side toward the radially outer side, that is, toward the stator side, and constitutes the permanent magnet pair 23.

  The permanent magnet 23 </ b> A and the permanent magnet 23 </ b> B are arranged so that the same polar surfaces face each other. Thereby, between the permanent magnet 23A and the permanent magnet 23B, the magnetic pole part 24 having the same polarity as the opposing polar surface is formed. Thus, the magnetic pole part 24 is formed as an N magnetic pole or an S magnetic pole depending on the polarity of the permanent magnets 23A and 23B arranged in a V shape.

  The pair of permanent magnets 23A and 23B are arranged such that the directions of the polar surfaces of the permanent magnet pairs 23 adjacent in the circumferential direction are opposite to each other. Thereby, the polarity of the magnetic pole part 24 is reversed between the magnetic pole parts 24 adjacent in the circumferential direction, that is, the reverse polarity. Therefore, in the rotor 20, the magnetic pole portions 24 (denoted as “N” in FIG. 1) and the magnetic pole portions 24 of the S magnetic pole (denoted as “S” in FIG. 1) are alternately formed in the circumferential direction. Is done.

  Thus, the rotor 20 has a reverse salient pole structure having a plurality of permanent magnet pairs 23 in which a pair of permanent magnets 23A and 23B are arranged in a V shape.

  In the reverse salient pole structure, the inductance in the d-axis direction (d-axis inductance Ld) passing between the pair of permanent magnets 23A and 23B passes between the pair of permanent magnets 23 adjacent in the circumferential direction. It has characteristics smaller than the magnetically orthogonal q-axis direction inductance (q-axis inductance Lq). Therefore, in the inverted salient pole structure, reluctance torque corresponding to the difference between the d-axis inductance Ld and the q-axis inductance Lq can be generated in addition to the magnet torque generated by the permanent magnet pair 23. Thereby, the torque density in the rotary electric machine 1 can be improved.

  Further, flux barriers 25a and 25b are formed on the rotor core 21 so as to be adjacent to the pair of permanent magnets 23A and 23B. The flux barriers 25a and 25b limit the wraparound of the magnetic flux.

  As shown in FIG. 1, a plurality of grooves 30 that are recessed inward in the radial direction are formed on the outer peripheral surface 20 a of the rotor 20. The groove portion 30 is formed only on the outer peripheral surface 20a of the rotor 20 in which the magnetic pole portion 24 of the N magnetic pole is formed. The groove part 30 may be formed only in the magnetic pole part 24 of the S magnetic pole. That is, the groove portion 30 only needs to be formed in either the magnetic pole portion 24 of the N magnetic pole or the magnetic pole portion 24 of the S magnetic pole.

  As shown in FIG. 2, the grooves 30 are formed on both sides of the rotor 20 in the circumferential direction across the d axis on the outer peripheral surface 20 a of the rotor 20 where the magnetic pole portion 24 of the N magnetic pole is formed. The pair of groove portions 30 have a line-symmetric shape with respect to the d axis.

  The groove part 30 is formed in a taper shape. The taper shape is a shape in which the circumferential groove width of the rotor 20 becomes narrower from the outer peripheral surface 20a of the rotor 20 toward the radially inward side of the rotor 20. As the taper shape, for example, a trapezoidal shape, a triangular shape, a semicircular shape, or a warhead shape, various shapes can be used as long as the groove width in the circumferential direction decreases from the radially outward side to the inward side of the rotor 20. The shape can be adopted.

  As shown in FIG. 3, the groove portion 30 has a pair of inclined surfaces 31 formed on both sides in the circumferential direction of the rotor 20 and a bottom surface 32 connecting the pair of inclined surfaces 31.

  When the groove portion 30 and the slot 13 of the stator 10 overlap each other in the radial direction, that is, when the center of the groove width of the groove portion 30 coincides with the center of the circumferential width of the slot 13 (see FIG. 3). Are arranged under predetermined conditions with respect to the slot 13 in the state shown in FIG.

  Specifically, when a line passing through the side surfaces 13a on both sides in the circumferential direction of the slot 13 and going inward in the radial direction of the rotor 20 is an imaginary line Ls, the pair of inclined surfaces 31 intersect with the imaginary line Ls, respectively. Arranged to do. Preferably, it is desirable that the pair of inclined surfaces 31 be arranged so that the virtual line Ls intersects the center of the inclined surface 31 in the circumferential direction.

  Thus, in the present embodiment, the groove width of the groove portion 30 is set to a dimension that takes into account the circumferential width of the slot 13 of the stator 10. As a result, a gap between the rotor 20 and the stator 10 by the groove 30 can be secured, and an effective magnetic path can be secured between the rotor 20 and the stator 10 even when the groove 30 is provided. .

  Here, if the depth of the groove portion 30 in the radial direction is too large, magnetic saturation may occur in the magnetic pole portion 24 of the N magnetic pole. Further, if the depth of the groove portion 30 in the radial direction is too small, the groove portion 30 cannot secure a sufficient gap between the rotor 20 and the stator 10. Therefore, in the present embodiment, the depth of the groove portion 30 in the radial direction is such that no magnetic saturation occurs in the magnetic pole portion 24 of the N magnetic pole, and a sufficient gap can be secured between the rotor 20 and the stator 10. Is set.

  The corners of the groove 30, specifically, the corners 30 a that connect the outer peripheral surface 20 a of the rotor 20 and the inclined surface 31, and the corners 30 b that connect the inclined surface 31 and the bottom surface 32, have a predetermined radius of curvature. The cross-sectional shape of R is formed. For this reason, since each corner | angular part 30a, 30b of the groove part 30 becomes a curve shape with a smooth cross-sectional shape, the air resistance at the time of rotation of the rotor 20 can be reduced. In addition, each corner | angular part 30a, 30b of the groove part 30 may be the cross-sectional shape which has a vertex.

  Next, the effect of the rotary electric machine 1 which concerns on a present Example is demonstrated with reference to FIGS.

  In a non-energized permanent magnet type rotating electrical machine, a magnetic attractive force is generated between the stator and the rotor by the magnetic flux generated from the permanent magnet. The magnetic attractive force changes due to the magnetic resistance in the path through which the magnetic flux flows. Since the flow of magnetic flux increases as the magnetic resistance decreases, the magnetic attractive force increases as the magnetic resistance decreases.

  In the IPMSM, stator teeth with high permeability and slots made of air with high magnetic resistance are alternately arranged in the circumferential direction in the stator core. The magnetoresistance of the stator teeth is much greater than the magnetoresistance in slots made of air. For this reason, pulsation occurs in the amount of magnetic flux flowing through the permanent magnet with respect to the rotational position of the rotor.

  Thereby, pulsation also occurs in the magnetic attractive force. Such pulsation of the magnetic attractive force is referred to as cogging torque. In other words, the cogging torque can be said to be a torque generated positively or negatively due to a change in magnetic attraction force accompanying the rotation of the rotor in a non-energized state.

  The cogging torque is preferably as small as possible because it relates to vibration and noise when driving the rotating electrical machine and disturbances in control.

  Further, in a hybrid vehicle, an efficient rotating electrical machine is used as a drive source in place of an inefficient engine in a low speed range for the purpose of improving fuel consumption. For this reason, when using a rotary electric machine as a drive source of a hybrid vehicle, in addition to generating a large torque for starting, it is required to reduce torque ripple from the viewpoint of stability.

  In the rotating electrical machine 1 according to the present embodiment, the pair of groove portions 30 is formed only on the outer peripheral surface 20a of the rotor 20 on which the magnetic pole portion 24 of the N magnetic pole is formed, thereby reducing cogging torque and torque ripple. Can do.

  Hereinafter, the principle capable of reducing the cogging torque in the rotating electrical machine 1 according to the present embodiment will be described in comparison with a rotating electrical machine in which the groove portion 30 is not formed (hereinafter referred to as a “rotating electrical machine according to a comparative example”). . The rotating electrical machine according to the comparative example is not provided with the groove 30 and the other configuration is the same as that of the rotating electrical machine 1 according to the present embodiment.

  As shown in FIG. 2, the rotating electrical machine 1 according to the present embodiment has twelve stator teeth 12 in one electrical angle period. Therefore, in the rotating electrical machine 1, the number of slots 13 between the stator teeth is also “12”.

  For this reason, in the rotating electrical machine 1 according to the present embodiment, the pulsation of the magnetic attractive force occurs 12 times in one electrical angle cycle. Therefore, the cogging torque in the rotating electrical machine 1 according to the present embodiment and the rotating electrical machine according to the comparative example mainly includes a 12th harmonic (hereinafter, referred to as “12th harmonic”) component.

  In the rotating electrical machine according to the comparative example, since the groove portion 30 is not formed, the pulsations of the magnetic attractive force are the same in both the N magnetic pole portion and the S magnetic pole portion. That is, in the rotating electrical machine according to the comparative example, the phase of the 12th harmonic in the N magnetic pole and the phase of the 12th harmonic in the S magnetic pole are the same.

  Here, if the phase of the 12th harmonic in the N magnetic pole and the phase of the 12th harmonic in the S magnetic pole can be reversed, the 12th harmonic in the N magnetic pole and the 12th harmonic in the S magnetic pole are canceled. Can do. As a result, the cogging torque between the N magnetic pole and the S magnetic pole is offset, and the cogging torque generated in the rotating electrical machine is reduced as a whole.

  Therefore, the rotating electrical machine 1 according to the present embodiment forms the pair of groove portions 30 only on the outer peripheral surface 20a of the rotor 20 on which the magnetic pole portion 24 of the N magnetic pole is formed, so that the phase of the 12th harmonic in the N magnetic pole is obtained. And the phase of the 12th harmonic in the S magnetic pole can be reversed. Thereby, the rotary electric machine 1 which concerns on a present Example can cancel the 12th harmonic in a N magnetic pole, and the 12th harmonic in a S magnetic pole.

  FIG. 4 shows that in the rotating electrical machine 1 according to the present embodiment, the phase of the 12th harmonic in the N magnetic pole and the phase of the 12th harmonic in the S magnetic pole are reversed, so that the cogging torque in the N magnetic pole and the cogging in the S magnetic pole are reversed. It shows how torque is offset. FIG. 4 shows a magnetic flux vector distribution between an electrical angle of 0 [deg] and an electrical angle of 30 [deg] corresponding to one cycle of the 12th harmonic. In the present embodiment, the magnetic flux vector distribution when the electrical angle is 0 [deg], 8 [deg], 22 [deg], and 30 [deg] is shown.

  As shown in FIG. 4, the magnetic flux has a characteristic that it tends to flow between the permanent magnets 23 </ b> A and 23 </ b> B and the stator teeth 12 through the shortest path. A magnetic attraction force is generated between the rotor 20 and the stator 10 by changing the path through which the magnetic flux flows.

  In FIG. 4, the magnetic attractive force is indicated by + and − arrows. In FIG. 4, the counterclockwise direction is defined as the + direction, and the clockwise direction is defined as the − direction. Therefore, the magnetic attraction force (hereinafter referred to as “magnetic attraction force (+)”) indicated by the + arrow is a force for rotating the rotor 20 in the counterclockwise direction. On the other hand, the magnetic attraction force (hereinafter referred to as “magnetic attraction force (−)”) indicated by the − arrow is a force for rotating the rotor 20 in the clockwise direction.

  In the electrical angle 0 [deg] and the electrical angle 30 [deg], the d-axis of the rotor 20 is positioned at the center in the circumferential direction of the stator teeth 12. For this reason, the magnetic flux of the permanent magnet 23 </ b> A and the magnetic flux of the permanent magnet 23 </ b> B flow symmetrically with respect to the stator 10 in both the N magnetic pole and the S magnetic pole. Thereby, in both the N magnetic pole and the S magnetic pole, the magnetic attractive force (+) and the magnetic attractive force (−) are balanced. As a result, as shown in FIGS. 5A and 5B, the cogging torque is substantially 0 [0 [deg] at both the N magnetic pole and the S magnetic pole at the electrical angle 0 [deg] and the electrical angle 30 [deg]. Nm].

  At an electrical angle of 15 [deg], the d-axis of the rotor 20 is positioned at the center in the circumferential direction of the slot 13. For this reason, the magnetic flux of the permanent magnet 23 </ b> A and the magnetic flux of the permanent magnet 23 </ b> B flow symmetrically with respect to the stator 10 in both the N magnetic pole and the S magnetic pole. Thereby, in both the N magnetic pole and the S magnetic pole, the magnetic attractive force (+) and the magnetic attractive force (−) are balanced. As a result, as shown in FIGS. 5A and 5B, at the electrical angle of 15 [deg], the cogging torque is substantially 0 [Nm] in both the N magnetic pole and the S magnetic pole.

  At an electrical angle of 8 [deg], a magnetic attractive force (−) is generated by the pair of grooves 30 formed in the N magnetic pole serving as a magnetic resistance. Specifically, a part of the magnetic flux acting on the magnetic attraction force (+) due to the presence of the groove 30 acts as a magnetic attraction force (−) by bypassing the groove 30. As a result, the magnetic flux that generates the magnetic attractive force (−) occupies most of the N magnetic pole, and as a result, the magnetic attractive force (−) is generated.

  In the S magnetic pole at an electrical angle of 8 [deg], since there is no pair of grooves 30, the magnetic flux that generates the magnetic attractive force (+) occupies most of the magnetic flux, and as a result, the magnetic attractive force (+) is generated. .

  Therefore, at the electrical angle of 8 [deg], the magnetic attractive force (−) generated at the N magnetic pole and the magnetic attractive force (+) generated at the S magnetic pole are opposite to each other and cancel each other. As a result, as shown in FIGS. 5A and 5B, at the electrical angle of 8 [deg], the phase of the cogging torque of the N magnetic pole and the phase of the cogging torque of the S magnetic pole are reversed.

  In the electrical angle 22 [deg], the direction in which the magnetic attractive force acts is opposite to that in the electrical angle 8 [deg]. Accordingly, even at the electrical angle 22 [deg], the magnetic attractive force (+) generated at the N magnetic pole and the magnetic attractive force (−) generated at the S magnetic pole are opposite to each other and cancel each other. As a result, as shown in FIGS. 5A and 5B, the phase of the cogging torque of the N magnetic pole and the phase of the cogging torque of the S magnetic pole are also reversed at the electrical angle 22 [deg].

  In this way, the cogging torque of the N magnetic pole and the cogging torque of the S magnetic pole cancel each other, and as shown in FIG. 5C, the cogging torque generated in the rotating electrical machine 1 is reduced as a whole. The cogging torque shown in FIG. 5 (c) is the sum of the cogging torque at the N magnetic pole shown in FIG. 5 (a) and the cogging torque at the S magnetic pole shown in FIG. 5 (b).

  In the rotating electrical machine 1 according to the present embodiment, since the pair of grooves 30 are formed in the N magnetic pole, as shown in FIGS. 5A and 5B, the phase of the cogging torque of the S magnetic pole is Thus, the phase of the cogging torque of the N magnetic pole is reversed (in this embodiment, the phase is deviated by 15 electrical degrees). Thus, the cogging torque of the N magnetic pole acts so as to cancel the cogging torque of the S magnetic pole, so that the cogging torque of the N magnetic pole and the cogging torque of the S magnetic pole are offset. As a result, as shown in FIG. 5C, the cogging torque generated in the rotating electrical machine 1 is reduced.

  As shown in FIG. 6, the cogging torque generated in the rotating electrical machine 1 according to the present embodiment is sufficiently reduced even when compared with the rotating electrical machine according to the comparative example. FIG. 7 shows the order components of the cogging torque generated in the rotating electrical machine 1 according to the present embodiment.

  As shown in FIG. 7, the cogging torque of the twelfth component generated in the rotating electrical machine 1 according to the present embodiment is significantly reduced compared to the cogging torque of the twelfth component generated in the rotating electrical machine according to the comparative example. Yes. Also, the cogging torque of the 24th order component is reduced as compared with the rotating electrical machine according to the comparative example.

  Further, in the rotating electrical machine 1 according to the present embodiment, by forming a pair of groove portions 30 in the N magnetic pole, as shown in FIG. 8, the torque ripple generated in the rotating electrical machine according to the comparative example also occurs in the torque ripple generated in the energized state. Compared to FIG. 9 shows the order component of the torque ripple generated in the rotating electrical machine 1 according to the present embodiment.

  As shown in FIG. 9, the torque of the twelfth component generated in the energized state in the rotating electrical machine 1 according to the present embodiment is significantly larger than the torque of the twelfth component generated in the energized rotating electrical machine according to the comparative example. Has decreased.

  As described above, in the rotating electrical machine 1 according to the present embodiment, the pair of groove portions 30 is formed only on the outer peripheral surface 20a of the rotor 20 on which the magnetic pole portion 24 of the N magnetic pole is formed. Further, the pair of groove portions 30 are formed on both sides in the circumferential direction with the d-axis in the magnetic pole portion 24 of the N magnetic pole.

  For this reason, the rotating electrical machine 1 according to the present embodiment can reverse the phase of the 12th harmonic in the N magnetic pole and the phase of the 12th harmonic in the S magnetic pole, and the cogging torque in the N magnetic pole and the cogging in the S magnetic pole. The torque can be offset. As a result, the rotating electrical machine 1 according to the present embodiment can suppress cogging torque and torque ripple.

  Further, the rotating electrical machine 1 according to the present embodiment does not increase the magnetic resistance of the q-axis magnetic path by widening the gap between the rotor 20 and the stator 10 on the q-axis serving as the excitation axis. It can prevent that a pole ratio falls. Therefore, it can prevent that the output torque and efficiency of the rotary electric machine 1 fall.

  Further, in the rotating electrical machine 1 according to the present embodiment, since the pair of groove portions 30 have a line-symmetric shape with the d-axis interposed therebetween, 12 is generated at the N magnetic pole with respect to the phase of the 12th harmonic generated at the S magnetic pole. It is possible to realize a magnetic flux flow in which the phase of the second harmonic is reversed.

  Further, in the rotating electrical machine 1 according to the present embodiment, the pair of groove portions 30 are formed in a tapered shape, so that loss due to air resistance, that is, windage loss can be reduced.

  The structure for reducing the cogging torque and the torque ripple in the rotating electrical machine 1 according to the present embodiment is different from a so-called permanent magnet skew structure in which a plurality of permanent magnets arranged in the axial direction are arranged shifted in the circumferential direction. For this reason, the rotating electrical machine 1 according to the present embodiment can prevent the magnetization rate from decreasing and the leakage flux of the permanent magnet from increasing compared to the skew structure of the permanent magnet. Further, in the rotating electrical machine 1 according to the present embodiment, the assembly of the rotor 20 is easy as compared with the skew structure of the permanent magnet.

  In the rotating electrical machine 1 according to the present embodiment, the rotor 20 may be divided in the axial direction, and the divided rotor may be shifted in the rotation direction. In this case, cogging torque and torque ripple can be further suppressed.

  Moreover, the rotary electric machine 1 is not limited to vehicle-mounted use, For example, it can be used suitably also as drive sources, such as a wind power generation and a machine tool.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

DESCRIPTION OF SYMBOLS 1 Rotating electric machine 10 Stator 11 Stator core 12 Stator teeth 13 Slot 13a Side surface 14 Armature winding 20 Rotor 20a Outer peripheral surface 21 Rotor core 22 Slit pair 22A, 22B Slit 23 Permanent magnet pair 23A, 23B Permanent magnet 24 Magnetic pole part 30 Groove part 30a, 30b Corner portion 31 Inclined surface 32 Bottom surface Ls Virtual line

Claims (4)

A rotating electrical machine comprising a stator in which a plurality of slots in which armature windings are arranged and a rotor in which a plurality of permanent magnets are embedded in a rotor core,
The rotor has a magnetic pole portion formed by the permanent magnets arranged in a V shape spreading toward the stator side,
The permanent magnet is arranged so that the polarity of the magnetic pole portion adjacent in the circumferential direction of the rotor is opposite,
A rotating electrical machine characterized in that grooves are formed on both sides in the circumferential direction across the d-axis on the outer peripheral surface of the rotor where the magnetic pole portion of either the N magnetic pole or the S magnetic pole is formed.   The rotating electrical machine according to claim 1, wherein the pair of grooves have a line-symmetric shape with respect to the d-axis.   The said groove part is formed in the taper shape from which the groove width of the said circumferential direction becomes narrow toward the inner side of the radial direction of the said rotor from the outer peripheral surface of the said rotor. The rotating electrical machine described in 1. The groove has inclined surfaces formed on both sides in the circumferential direction,
The said inclined surface is arrange | positioned so that it may cross | intersect the virtual line which goes to the inner side of the radial direction of the said rotor through the side surface of the circumferential direction both sides of the said slot. The rotating electrical machine according to any one of claims.

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