CN115882637A - Rotating electrical machine - Google Patents

Abstract

The invention provides a rotating electric machine capable of suppressing reduction of average torque and reducing 6 th harmonic torque ripple. A plurality of permanent magnets (122) of a rotating electrical machine (100) are magnetized in the same direction along the radial direction of a rotor (rotor) (20). The rotor (20) has a plurality of salient pole portions (126) located between adjacent permanent magnets (122). The length (width A) of the salient pole portion (126) in the circumferential direction of the rotor (20) is longer than the length (width C) of the teeth (116) in the circumferential direction of the rotor (20). Further, the distance (Gs) of the salient pole portion (126) and the tooth (116) in the radial direction of the rotor (20) is longer than the distance (G) of the permanent magnet (122) and the tooth (116) in the radial direction of the rotor (20).

Description

Rotating electrical machine

Technical Field

The present invention relates to a rotating electric machine.

Background

A conventional rotating electric machine is, for example, a brushless motor described in patent document 1.

The brushless motor described in patent document 1 is used as a pressurizing source of an electric brake system. The brushless motor includes a stator formed by winding a coil around a plurality of teeth provided in a circumferential direction, and a rotor facing the stator. The rotor has magnet magnetic pole portions having magnets in the circumferential direction of the rotor core, and a core portion provided between the magnet magnetic pole portions. The core portion functions as the other magnetic pole.

In the alternating-pole rotor structure such as the brushless motor described in patent document 1, a magnetic path in which magnetic flux from the magnet is linked is provided in a salient pole portion between the magnet and the magnet.

Then, the stator and the rotor of the motor are opposed via a gap. When the change in the magnetic conductance in the middle of the gap is observed in the circumferential direction, the magnetic conductance becomes higher at a portion corresponding to the salient pole portion.

When the magnetic conductance increases at a portion corresponding to the salient pole portion, a harmonic voltage of an even-order component is generated in the induced electromotive force of the motor. As a result, harmonic torque ripple of 3 rd order integral multiple, which is not generated in the surface magnet rotor structure, is output. In particular, the harmonic torque ripple of the order 6 integral multiple is a component that is likely to dominate the total torque ripple among the harmonic components included in the torque ripple of the load torque. Therefore, in order to suppress vibration noise of the motor, it is necessary to reduce harmonic torque ripple of 6 times as large as an integer.

A method of reducing torque ripple of an alternating pole rotor structure is described in patent document 2, for example. In the motor having the alternating pole structure described in patent document 2, a ratio B/a of a gap distance a of the rotor with respect to the stator on the magnet side to a gap distance B of the salient pole side is set to any appropriate value of 1 < B/a.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2019-126138

Patent document 2: japanese patent laid-open publication No. 2011-83119

Disclosure of Invention

Technical problems to be solved by the invention

However, in the motor described in patent document 2, since the magnetic resistance of the gap of the salient pole portion increases, the effect of reducing the torque ripple is obtained, but the average torque also decreases. In order to suppress the decrease in the average torque, for example, it is necessary to increase the winding current to increase the magnetomotive force of the stator. However, in this case, the motor is increased in size.

In view of the above problems, an object of the present invention is to provide a rotating electric machine capable of suppressing a reduction in average torque and reducing 6 th harmonic torque ripple.

Means for solving the problems

In order to solve the above problems and achieve the object of the present invention, a rotating electric machine includes: an annular rotor having a plurality of permanent magnets and rotating about a rotating shaft; and an annular stator having a plurality of teeth facing the plurality of permanent magnets via gaps in a radial direction of the rotor. The plurality of permanent magnets are magnetized in the same direction along the radial direction of the rotor. The rotor has a plurality of salient pole portions located between adjacent permanent magnets. The length of the salient pole portions in the circumferential direction of the rotor is longer than the length of the teeth in the circumferential direction of the rotor. Further, the distance between the salient pole portions and the teeth in the radial direction of the rotor is longer than the distance between the permanent magnets and the teeth in the radial direction of the rotor.

Effects of the invention

According to the rotating electric machine configured as described above, the 6 th harmonic torque ripple can be reduced while suppressing a decrease in average torque.

Further, the problems, structures, and effects other than those described above will be further apparent from the following description of the embodiments.

Drawings

Fig. 1 is an overall configuration diagram of a rotating electric machine according to embodiment 1 of the present invention.

Fig. 2 is a cross-sectional view of the rotating electric machine according to embodiment 1 of the present invention cut on a plane perpendicular to the rotation axis.

Fig. 3 is a partially enlarged view of a rotating electric machine according to embodiment 1 of the present invention.

Fig. 4 is a schematic diagram showing the path of magnetic flux in the rotating electric machine according to embodiment 1 of the present invention.

Fig. 5 is a distribution diagram showing magnetic flux density distributions of air gaps in the rotating electric machine according to embodiment 1 of the present invention and a conventional rotating electric machine.

Fig. 6 is a diagram comparing harmonic torque ripple in the rotary electric machine according to embodiment 1 of the present invention and a conventional rotary electric machine.

Fig. 7 is a cross-sectional view of the rotating electric machine according to embodiment 2 of the present invention cut on a plane perpendicular to the rotation axis.

Fig. 8 is a partially enlarged view of a rotating electric machine according to embodiment 2 of the present invention.

Fig. 9 is a schematic diagram showing the path of magnetic flux in the rotating electric machine according to embodiment 2 of the present invention.

Fig. 10 is a distribution diagram showing magnetic flux density distribution in the gap between the rotating electric machines according to embodiments 1 and 2 of the present invention and a conventional rotating electric machine.

Fig. 11 is a diagram comparing harmonic torque ripple in the rotary electric machines according to embodiment 1 and embodiment 2 of the present invention and a conventional rotary electric machine.

Fig. 12 is a cross-sectional view of the rotating electric machine according to embodiment 3 of the present invention cut on a plane perpendicular to the rotation axis.

Fig. 13 is a partially enlarged view of a rotating electric machine according to embodiment 3 of the present invention.

Fig. 14 is a diagram showing harmonic torque ripple in the rotating electric machine according to embodiment 3 of the present invention.

Detailed Description

1. Embodiment mode 1

A rotating electric machine according to embodiment 1 of the present invention will be described below. In the drawings, the same reference numerals are given to the common members.

[ ROTARY ELECTRIC MACHINE ]

First, the structure of the rotating electric machine according to embodiment 1 will be described with reference to fig. 1 and 2.

Fig. 1 is an overall configuration diagram of a rotating electric machine according to embodiment 1. Fig. 2 is a cross-sectional view of the rotating electric machine according to embodiment 1 cut on a plane perpendicular to the rotation axis.

Fig. 1 is a sectional view of a rotating electric machine cut on a plane parallel to a rotation axis. A rotating electrical machine 100 according to embodiment 1 is an external permanent magnet rotor synchronous motor having an alternating-pole rotor structure. The rotating electric machine 100 has 12 coils and 10 magnetic poles.

As shown, the rotating electric machine 100 includes: a ring-shaped stator (stator) 10; a ring-shaped rotor 20 (rotor) rotatably supported on a radially outer side of the stator 10; a rotor case 6 covering the rotor 20; and a shaft 4 fixed to the rotor case 6.

The rotor case 6 does not necessarily need to cover the entirety of the rotor 20. The rotor case 6 is configured as a member connecting the shaft 4 and the rotor 20. The rotor 20 and the rotor case 6 may be fixed by various methods. The rotor 20 is opposed to the stator 10 via a gap 102 in the radial direction of the rotor 20. The rotor 20 rotates about the rotation axis of the shaft 4.

Hereinafter, the rotation axis side close to the shaft 4 is referred to as "inner circumference side", and the rotation axis side distant from the shaft 4 is referred to as "outer circumference side". The direction of a straight line perpendicularly intersecting the rotation axis of the shaft 4 is referred to as a "radial direction", and the direction of rotation of the shaft 4 is referred to as a "circumferential direction".

As shown in fig. 2, the rotor 20 includes: an annular rotor yoke 120 made of a magnetic material; a plurality of salient pole portions 126 protruding radially inward of rotor yoke 120; and a plurality of permanent magnets 122 fixed to an inner circumferential side surface of the rotor yoke 120.

The plurality of permanent magnets 122 and the plurality of salient pole portions 126 are alternately arranged in the circumferential direction. The magnetization direction of the plurality of permanent magnets 122 is the same direction as the radial direction. The N poles of the plurality of permanent magnets 122 all face the radially inner peripheral side. That is, the plurality of permanent magnets 122 are magnetized in the same direction along the radial direction.

Each of the plurality of permanent magnets 122 and the plurality of salient pole portions 126 is provided with 5. Therefore, the plurality of permanent magnets 122 and the plurality of salient pole portions 126 constitute 5 pole pairs, i.e., 10 magnetic poles.

In the present embodiment, a plurality of permanent magnets 122 are affixed to the inner circumferential surface of rotor yoke 120. However, the method of fixing the permanent magnet according to the present invention is not limited to the attachment, and for example, the following method may be employed: grooves for respectively accommodating a plurality of permanent magnets are provided on the inner peripheral surface of the rotor yoke, and the permanent magnets are fitted into the grooves. Further, the following method may be adopted: the plurality of permanent magnets are covered with a magnetic body so as to be integrated with the rotor yoke.

Examples of the material of the permanent magnet 122 include ferrite-based, neodymium-based, and samarium-cobalt-based magnets. As shown in fig. 2, a cross section cut on a plane perpendicular to the rotation axis of the permanent magnet 122 has a tile shape. However, the cross section cut on a plane perpendicular to the rotation axis of the permanent magnet 122 may also be a flat plate shape. Further, the permanent magnet of each magnetic pole may be formed by arranging a plurality of magnets of the same magnetization direction in parallel in the rotation axis direction of the shaft 4, in the circumferential direction.

The stator 10 has: a substantially cylindrical stator yoke 110 made of a magnetic material; a plurality of teeth 116 radially protruding from the outer circumferential side surface of the stator yoke 110; and an armature winding 112 wound around the teeth 116. There are 12 of the plurality of teeth 116. The plurality of teeth 116 are arranged at equal intervals in the circumferential direction. Further, the space between adjacent teeth 116, that is, the groove 104, is provided with 12 as in the case of the plurality of teeth 116. That is, the rotating electric machine 100 is a motor having 12 slots and 10 poles.

The plurality of teeth 116 are opposed to the plurality of permanent magnets 122 and the plurality of salient pole portions 126 of the rotor 20 via the air gap 102. Tooth 116 has a waist portion 116a continuous with stator yoke 110, and a flange portion 116b provided on the side of gap 102 of waist portion 116 a. The flange portion 116b is formed in a substantially elliptical shape protruding in the circumferential direction.

The space between adjacent teeth 116, i.e., the groove 104, is formed in a semi-closed shape by the flange portion 116b of the tooth 116. The groove according to the present invention may be an open groove shape in which the teeth are not provided with the flange portion.

The number of armature windings 112 is 12, which is the same as the number of teeth 116. The armature winding 112 forms a coil of arbitrary shape. For the armature winding 112, for example, 1 or more copper wires are used which are obtained by coating an insulating film (e.g., a varnish, an engineering plastic, etc.) on an electric conductor mainly composed of copper. Armature winding 112 has a conductor 112A and a conductor 112B disposed in slot 104, respectively. When the rotary electric machine 100 is driven, the conductor 112A and the conductor 112B are energized in a direction opposite to the rotation shaft direction with respect to each other.

An insert such as a tape of a non-combustible material, a resinous bobbin, or the like may be provided between the armature winding 112 and the teeth 116. This can enhance the insulation property. In addition, the stator according to the present invention may be formed by impregnating the stator with varnish, resin, or the like to fix the armature winding to the teeth.

As the magnetic bodies constituting the rotor yoke 120 and the stator yoke 110, a laminated body in which magnetic steel plates and electric insulators are laminated is used. This can reduce eddy current loss. In the rotor yoke and the stator yoke according to the present invention, an integrated (bulk) magnetic body may be used. This can reduce the material cost and the processing cost.

[ relationship between permanent magnet, salient pole, and tooth ]

Next, the relationship among the permanent magnet 122, the salient pole portion 126, and the teeth 116 will be described with reference to fig. 3.

Fig. 3 is a partially enlarged view of the periphery of the salient pole portion 126 in the rotating electric machine 100.

As shown in fig. 3, the length along the circumferential direction of the salient pole portion 126 is defined as a width a. The length along the circumferential direction of the teeth 116 is defined as a width C. The width a is obtained by converting the length along the circumferential direction of the salient pole portion 126 into an electrical angle. The width C is obtained by extending the width of the waist portion 116a of the tooth 116 to a position facing the gap 102 and converting the extended width into an electrical angle.

Although the teeth 116 of the present embodiment are parallel teeth, the width C can be defined by the same concept even in trapezoidal teeth. The width a of salient pole portion 126 is wider than the width C of tooth 116 (a > C).

Further, a distance in the radial direction between the outer circumferential side surface of the tooth 116 and the inner circumferential side surface of the permanent magnet 122 is set as a distance G. Then, the distance in the radial direction between the outer peripheral side surface of the tooth 116 and the inner peripheral side surface of the salient pole portion 126 is set as a distance Gs. In the present embodiment, the distance Gs is made longer than the distance G (Gs > G).

The width a in the present embodiment is 170 degrees in electrical angle. However, the electrical angle of the width a according to the present invention is designed to be 180 degrees to 150 degrees (the number of slots S, the number of poles P,360 degrees × P/2/S). In the combination of 12 slots and 10 poles, the width C of the tooth 116 is 150 degrees at maximum in the electrical angle. In practice, a space for arranging the armature winding 112 is required, and therefore, the width C of the teeth 116 is less than 150 degrees in electrical angle. Therefore, the width a of the salient pole portion 126, which is larger than the width C of the tooth 116, is set to 150 degrees or more in the electrical angle. In the present embodiment, the distance Gs is set to be 2 times the distance G (Gs = 2G). However, the distance Gs may be larger than 2 times the distance G (Gs > 2G).

[ path of magnetic flux ]

Next, the path of the magnetic flux from the magnet in the rotating electric machine 100 will be described with reference to fig. 4.

Fig. 4 is a schematic diagram illustrating a path of magnetic flux of the rotating electric machine 100.

The dashed curve 160 shown in fig. 4 is the magnetic flux from the permanent magnet 122. Further, a broken line 150 indicates a middle portion of the distance G. As shown in fig. 4, the magnetic flux from each permanent magnet 122 passes through the adjacent 2 teeth 116 of the stator 10, and returns to each permanent magnet 122 from the adjacent salient pole portion 126 via the air gap 102.

Therefore, a magnetic pole in the opposite direction to the adjacent permanent magnet 122 (S pole with respect to the N pole) is generated in the salient pole portion 126. This makes it possible to obtain a magnetic pole pair similar to that in the case where the salient pole portion 126 is replaced with a permanent magnet of opposite polarity. As a result, the rotating electrical machine (motor) can be rotated by the same current as that of a general surface magnet type synchronous motor.

In the present embodiment, the height of the salient pole portion 126 is made lower than the height of the permanent magnet 122, and the distance Gs is made longer than the distance G (Gs > G) (see fig. 3). Thereby, the gap between the salient pole portion 126 and the teeth 116 is widened. As a result, the magnetic resistance of the salient pole portions 126 in the path of the magnetic flux increases as a whole, and the interlinkage magnetic flux decreases. In the present embodiment, the width a of the salient pole portion 126 is larger than the width C of the teeth 116. This reduces leakage of magnetic flux in salient pole portion 126.

[ magnetic flux density ]

Next, the magnetic flux densities of the rotating electric machine according to the present embodiment and a conventional rotating electric machine will be described with reference to fig. 5.

Fig. 5 is a distribution diagram showing magnetic flux density distribution in the gap between rotating electric machine 100 and a conventional rotating electric machine.

As described above, in the rotating electric machine 100 according to the present embodiment, the distance Gs is longer than the distance G (see fig. 3). On the other hand, in a conventional alternating-pole motor (rotating electrical machine), a distance Gs is set to be the same as a distance G (Gs = G).

Fig. 5 is a distribution diagram showing the magnitude of the radial magnetic flux density at the intermediate portion (broken line 150 in fig. 4) of the distance G when the electrical angle of the rotation angle is θ and the intermediate portion between the permanent magnet 122 and the salient pole portion 126 in the circumferential direction is 0 degree. As shown in fig. 5, the magnetic flux density distribution of the conventional rotating electric machine is distorted by the influence of the flux guide of the stator, but is distributed in a substantially sine wave shape.

The salient pole portion 126 ranges from 0 degrees to 180 degrees as shown in fig. 5. Since the rotating electric machine 100 of the present embodiment has the distance Gs longer than the distance G, the magnetic flux density distribution in which the level of the magnetic flux density of the salient pole portions 126 is simply lowered is obtained as compared with the conventional rotating electric machine. Then, as the frequency components, the frequency components 1, 2, 3, and 5 times are reduced. For example, the frequency component of 1 time is reduced by the enlargement of the gap 102, and the frequency component of 2 times or more is determined by the combination of the number of slots and the number of poles. In the present embodiment, the width a of the salient pole portion 126 is made larger than the width C of the tooth 116. Therefore, a decrease in average torque caused by a decrease in magnetic flux density distribution can be suppressed.

The 6 th-order component of the harmonic torque ripple may be generated by the interaction of 2 poles of the permanent magnet 122 on the rotor 20 side and the teeth 116 of an integral multiple of 3 on the stator 10 side. Therefore, by distorting the magnetic flux density distribution of the salient pole portion 126, which is a virtual magnetic pole (reducing the fundamental wave of the magnetic flux density distribution), the effect of reducing the magnitude of the harmonic torque ripple can be obtained. In particular, the 6 th order torque ripple is caused by the 5 th order and 7 th order components of the magnetic flux and the voltage harmonic, and therefore, it is important to reduce the 5 th order and 7 th order components of the magnetic flux and the voltage harmonic.

[ higher harmonic torque ripple ]

Next, torque ripples of the rotating electric machine according to embodiment 1 and a conventional rotating electric machine will be described with reference to fig. 6.

Fig. 6 is a diagram comparing harmonic torque ripples in the rotating electric machine 100 and a conventional rotating electric machine.

Fig. 6 shows the analysis result of the harmonic components of the torque when the three-phase sinusoidal current is conducted to the armature winding 112 so that the average torque is equal. Here, the torque ripple is normalized by the ratio of each higher harmonic component to the average torque, and is expressed by percentage. As shown in fig. 6, the rotating electric machine 100 according to the present embodiment can reduce 6 th harmonic torque ripple compared to a conventional rotating electric machine. Therefore, the 6 th harmonic torque ripple can be reduced while suppressing the decrease in the average torque.

2. Embodiment mode 2

Next, a rotating electric machine according to embodiment 2 will be described. In the drawings, the same reference numerals are given to the common members.

[ ROTARY ELECTRIC MACHINE ]

First, the structure of the rotating electric machine according to embodiment 2 will be described with reference to fig. 7 and 8.

Fig. 7 is a cross-sectional view of the rotating electric machine according to embodiment 2 cut on a plane perpendicular to the rotation axis.

Fig. 8 is a partially enlarged view of the rotating electric machine according to embodiment 2.

The rotating electric machine 200 according to embodiment 2 has the same configuration as the rotating electric machine 100 according to embodiment 1 (see fig. 2). Rotating electric machine 200 differs from rotating electric machine 100 in a salient pole portion 226. Therefore, the salient pole portion 226 will be described here, and the description of the structure common to embodiment 1 will be omitted.

As shown in fig. 7, the salient pole portion 226 of the rotating electrical machine 200 is provided with a concave portion 228. The concave portion 228 is formed as 1 circular arc-shaped recess in the center portion of the inner peripheral surface of the salient pole portion 226. That is, the cross section of the recess 228 perpendicular to the rotation axis of the shaft 4 is formed in an arc shape.

In the concave portion of the salient pole portion according to the present invention, the cross section orthogonal to the rotation axis of the shaft 4 is not limited to the circular arc shape, and for example, the cross section orthogonal to the rotation axis of the shaft 4 may be a polygonal or V-shaped groove. Even when the cross section of the recess is a polygonal or V-shaped groove, the same effect as that obtained when the cross section of the recess is an arc can be obtained. This effect will be described later.

As shown in fig. 8, the length along the circumferential direction of the salient pole portion 226 is defined as a width a. The length along the circumferential direction of the recess 228 is defined as a width B. The length along the circumferential direction of the teeth 116 is defined as a width C. The widths a and C are obtained by converting the widths a and C into electrical angles, and are the same as those in embodiment 1.

The width B is obtained by converting the length along the circumferential direction of the recessed portion 228 into an electrical angle.

The width a of salient pole portion 226 is wider than the width C of tooth 116 (a > C). Further, the width a of the salient pole portion 226 is wider than the width B of the concave portion 228 (a > B). If the width B of the concave portion 228 is excessively large, the magnetic resistance of the salient pole portion 126 increases as described with reference to fig. 4. Therefore, the width B of the recess 228 is set to a range of ± 20% with respect to the width C. Further, corners of both ends at the width a of the salient pole portion 226 are cut in an arc shape.

The distance in the radial direction between the outer circumferential side surface of the tooth 116 and the inner circumferential side surface of the permanent magnet 122 is set as a distance G. The distance in the radial direction between the outer peripheral side surface of the tooth 116 and the portion of the inner peripheral side surface of the salient pole portion 226 other than the recessed portion 228 is equal to the distance G. Then, the distance from the point where the concave portion 228 in the salient pole portion 226 is most dented to the outer circumferential side surface of the tooth 116 is set as a distance Gs. That is, the distance Gs is a distance from a radially outermost point in the inner peripheral side surface of the salient pole portion 226 to the outer peripheral side surface of the tooth 116.

In the present embodiment, the distance Gs is made longer than the distance G (Gs > G). Specifically, the distance Gs is set to be 3 times the distance G (Gs = 3G). That is, the depth (length in the radial direction) of the recess 228 is 2 times the distance G.

[ path of magnetic flux ]

Next, the path of the magnetic flux from the magnet in the rotating electric machine 200 will be described with reference to fig. 9.

Fig. 9 is a schematic diagram showing a path of magnetic flux of the rotating electric machine 200.

The dashed curve 160 shown in fig. 9 is the magnetic flux from the permanent magnet 122. In addition, the dotted line 150 indicates the middle of the distance G. As shown in fig. 9, the magnetic flux from each permanent magnet 122 passes through the adjacent 2 teeth 116 of the stator 10 and returns to each permanent magnet 122 from the adjacent salient pole portion 226 via the air gap 102. The magnetic resistance of the concave portion 228 of the salient pole portion 226 is high. Therefore, the magnetic flux of the salient pole portion 226 concentrates near both sides of the concave portion 228.

[ magnetic flux density ]

Next, the magnetic flux densities of the rotating electric machines according to embodiment 2 and embodiment 1 and a conventional rotating electric machine will be described with reference to fig. 10.

Fig. 10 is a distribution diagram showing magnetic flux density distribution in gaps between rotating electric machine 200 and rotating electric machine 100 and a conventional rotating electric machine.

As shown in fig. 10, the magnetic flux density distribution of the conventional rotating electric machine and the rotating electric machine 100 according to embodiment 1 is distributed in a substantially sine wave shape. On the other hand, in the magnetic flux density distribution of rotating electric machine 200 according to embodiment 2, the magnetic flux density of salient pole portion 226 fluctuates up and down due to the influence of concave portion 228, and the peak of the sine wave is distorted.

As the frequency components involved in the rotating electric machine 200, the frequency components of 1 st and 5 th times are decreased, and the frequency components of 3 rd and 6 th times are increased. The frequency components of the 3 rd order and the 6 th order are offset by the influence of the three-phase alternating current. Therefore, the rotary electric machine 200 can reduce 5-order frequency components contributing to reduction of 6-order torque ripple. That is, in the rotating electrical machine 100 according to embodiment 1, the harmonics of the magnetic flux density in a wide range are reduced, but in the rotating electrical machine 200, the harmonics (5 th order frequency components) that become the source of torque ripple can be further selectively reduced because the recess 228 is provided. In the present embodiment, the width a of the salient pole portion 226 is made larger than the width C of the tooth 116. Therefore, a decrease in the average torque caused by a decrease in the magnetic flux density distribution can be suppressed.

[ higher harmonic torque ripple ]

Next, torque ripple between the rotating electric machines according to embodiment 2 and embodiment 1 and a conventional rotating electric machine will be described with reference to fig. 11.

Fig. 11 is a diagram comparing harmonic torque ripples in the rotary electric machine 200 and the rotary electric machine 100 with those in a conventional rotary electric machine.

Fig. 11 shows the analysis result of the harmonic components of the torque when the three-phase sinusoidal current is supplied to the armature winding 112 so that the average torque is equal. Here, the torque ripple is normalized by the ratio of each higher harmonic component to the average torque, and is expressed by percentage. As shown in fig. 11, the rotating electric machine 200 according to embodiment 2 can reduce 6 th and 12 th harmonic torque ripple compared to conventional rotating electric machines.

Since the rotary electric machine 200 is provided with the recess 228, the harmonic torque ripple of order 6 and order 12 can be reduced as compared with the rotary electric machine 100 according to embodiment 1. In particular, although the rotating electric machine 100 according to embodiment 1 cannot reduce the 12 th harmonic torque ripple, the rotating electric machine 200 can also reduce the 12 th harmonic torque ripple. Therefore, the harmonic torque ripple of 6 th order integral multiple can be reduced while suppressing the decrease in average torque.

3. Embodiment 3

Next, a rotating electric machine according to embodiment 3 will be described. In the drawings, the same reference numerals are given to the common members.

[ ROTARY ELECTRIC MACHINE ]

First, the structure of the rotating electric machine according to embodiment 3 will be described with reference to fig. 12 and 13.

Fig. 12 is a cross-sectional view of the rotating electric machine according to embodiment 3 cut along a plane perpendicular to the rotation axis. Fig. 13 is a partially enlarged view of the rotating electric machine according to embodiment 3.

The rotating electric machine 300 according to embodiment 3 has the same configuration as the rotating electric machine 100 according to embodiment 1 (see fig. 2). As shown in fig. 12, the rotary electric machine 300 has 36 teeth 116, 16 permanent magnets 122, and 16 salient pole portions 326. That is, the rotating electrical machine 300 is a motor having 36 slots and 32 poles.

The rotary electric machine 300 differs from the rotary electric machine 100 in the number of teeth 116, permanent magnets 122, and salient poles 326, and the shape of the salient poles 326. Therefore, the salient pole portion 326 will be described here, and the description of the structure common to embodiment 1 will be omitted.

As shown in fig. 12 and 13, the salient pole portion 326 of the rotating electrical machine 300 is provided with 2 recesses 328. The 2 concave portions 328 are formed as 2 arc-shaped depressions on the inner peripheral surface of the salient pole portion 326. The 2 concave portions 328 are disposed at positions symmetrical with respect to the central portion of the inner peripheral surface of the salient pole portion 326.

As shown in fig. 13, the length along the circumferential direction of the salient pole portion 326 is defined as a width a. The length along the circumferential direction of the recess 328 is defined as the width D. The length along the circumferential direction of the teeth 116 is defined as a width C. The width a, the width C, and the width D are converted into electrical angles. The width a of salient pole portion 326 is wider than the width C of tooth 116 (a > C). The width D of each recess 328 is set to about half the width C of the tooth 116 (D = C/2). Further, the corners of both ends at the width a of the salient pole portion 326 are obliquely cut.

The distance in the radial direction between the outer circumferential side surface of the teeth 116 and the inner circumferential side surface of the permanent magnet 122 is set as a distance G. The distance in the radial direction between the outer peripheral side surface of the tooth 116 and the inner peripheral side surface of the salient pole portion 326 is equal to the distance G. Then, the distance from the point where the concave portion 328 in the salient pole portion 326 is most dented to the outer peripheral side surface of the tooth 116 is set as a distance Gs. That is, the distance Gs is a distance from a radially outermost point on the inner peripheral side surface of the salient pole portion 326 to the outer peripheral side surface of the tooth 116.

In the present embodiment, the distance Gs is made longer than the distance G (Gs > G). The distance Gs is set to 3 times the distance G (Gs = 3G). That is, the depth (radial length) of the recess 328 is 2 times the distance G.

Generally, in a motor (rotating electrical machine) having 36 slots and 16 pole pairs, an even-order component is mixed in a component of a magnetic flux/voltage harmonic. Therefore, in the alternating pole motor having 36 slots and 16 pole pairs, harmonic torque ripple of integral multiple of order 3 is generated largely.

Since the rotating electric machine 300 according to embodiment 3 has the concave portion as in embodiment 2, harmonic torque ripple of 6 th order integral multiple can be reduced. Further, by providing 2 recesses 328, the width D of each recess 328 is set to half the width C of the tooth 116, and the depth of the recess 328 is set to 2 times the distance G, so that harmonic torque ripple of 3 times the integer multiple can be reduced. In the present embodiment, the width a of the salient pole portion 326 is made larger than the width C of the teeth 116. Therefore, a decrease in average torque caused by a decrease in magnetic flux density distribution can be suppressed.

[ higher harmonic torque ripple ]

Next, torque ripple of the rotating electric machine according to embodiment 3 will be described with reference to fig. 14.

Fig. 14 is a diagram illustrating harmonic torque ripple in the rotating electric machine 300.

In fig. 14, embodiment 3 in which 2 recesses 328 are provided, an example in which no recess is provided for the salient pole portion 326, and an example in which 1 recess having the same width as the width C of the tooth 116 is provided for the salient pole portion 326 are compared. In the case where 1 recess is provided, the recess is disposed in the center of the inner peripheral surface of the salient pole portion 326.

As shown in fig. 14, the harmonic torque ripple of order 6 can be reduced by providing 1 recess as compared with the case where no recess is provided. However, in the case where 1 recess is provided, harmonic torque ripples of 3 rd order and 9 th order increase. In contrast, embodiment 3 provided with 2 recesses 328 can suppress the increase in harmonic torque ripple of order 3 and can reduce harmonic torque ripple of order 6, 9, or 12. As a result, embodiment 3 provided with 2 recesses 328 can reduce harmonic torque ripple as a whole.

4. Summary of the invention

As described above, the rotating electric machine 100 according to embodiment 1 includes: an annular rotor 20 (rotor) having a plurality of permanent magnets 122 and rotating about the rotation axis of the shaft 4; and a ring-shaped stator 10 (stator) having a plurality of teeth 116 opposed to the plurality of permanent magnets 122 via the air gap 102 in the radial direction of the rotor 20. The plurality of permanent magnets 122 are magnetized in the same direction along the radial direction of the rotor 20. The rotor 20 has a plurality of salient pole portions 126 located between adjacent permanent magnets 122. The length (width a) of the salient pole portion 126 in the circumferential direction of the rotor 20 is longer than the length (width C) of the tooth 116 in the circumferential direction of the rotor 20. The distance (distance Gs) of the salient pole portion 126 and the tooth 116 in the radial direction of the rotor 20 is longer than the distance (distance G) of the permanent magnet 122 and the tooth 116 in the radial direction of the rotor 20. Thus, the 6 th harmonic torque ripple can be reduced by distorting the magnetic flux density distribution of the salient pole portion 126, which is the virtual magnetic pole (reducing the fundamental wave of the magnetic flux density distribution). Further, the length (width a) of the salient pole portions 126 in the circumferential direction of the rotor 20 is made longer than the length (width C) of the teeth 116 in the circumferential direction of the rotor 20. Therefore, a decrease in the average torque caused by a decrease in the magnetic flux density distribution can be suppressed.

The salient pole portion 226 according to embodiment 2 has 1 concave portion 228 on the surface (inner circumferential surface) facing the air gap 102. This reduces the harmonic torque ripple of 6 times as large as an integer. Further, the salient pole portion 326 according to embodiment 3 has 2 recessed portions 328 on the surface (inner peripheral surface) facing the gap 102. This can reduce the harmonic torque ripple as a whole.

In addition, the concave portion 228 of embodiment 2 described above has an arc-shaped cross section perpendicular to the rotation axis of the shaft 4. The concave portion of the salient pole portion according to the present invention may be a groove having a polygonal or V-shaped cross section perpendicular to the rotation axis of the shaft 4. This makes it possible to easily provide the recess.

In addition, in the salient pole portion 326 according to embodiment 3, the two ends (both ends of the width a) in the circumferential direction of the rotor 20 are cut at an oblique angle. Thus, when the teeth 116 and the salient pole portions 326 are opposed to each other via the air gap 102, the degree of overlap between the teeth 116 and the salient pole portions 326 is gradually increased as compared with a case where there is a substantially right angle. As a result, the ease with which the magnetic flux passes through the salient pole portions 326 is gradually increased, and the force with which the teeth 116 are attracted to the salient pole portions 326 is gradually increased. Therefore, the harmonic torque ripple can be reduced.

In addition, in the salient pole portion 226 according to embodiment 2, the corners forming both ends (both ends of the width a) in the circumferential direction of the rotor 20 are cut in an arc shape. Thus, the degree of overlap between the teeth 116 and the salient pole portions 226 gradually increases as compared to embodiment 3. As a result, the harmonic torque ripple can be reduced as compared with embodiment 3.

In addition, the length (width a) of the salient pole portion 126 according to embodiment 1 and the salient pole portion 226 according to embodiment 2 along the circumferential direction of the rotor 20 is in the range of 180 degrees to 150 degrees in electrical angle. Accordingly, in the rotating electric machines 100 and 200 having 12 slots and 10 magnetic poles, the length (width a) of the salient pole portions 126 and 226 along the circumferential direction of the rotor 20 can be made longer than the length (width C) of the teeth 116 along the circumferential direction of the rotor 20.

The rotor 20 (rotor) according to embodiments 1 to 3 described above constitutes P (P is a natural number of 2 or more) magnetic pole numbers. The plurality of teeth 116 of the stator 10 (stator) is S (S is a natural number of 3 or more). Then, the number of slots per pole per phase (S/P/3) is 0.25 to 0.5. Thus, in a rotating electric machine having improved fractional slots of the output voltage waveform, harmonic torque ripple of 6 th order integral multiple can be reduced.

The rotor 20 (rotor) according to embodiments 1 to 3 is disposed outside the stator 10 (stator). That is, the rotor 20 (rotor) according to embodiments 1 to 3 is an outer rotor. This makes it possible to form the salient pole portion into a shape that widens as the distance from the air gap increases. As a result, the magnetic flux can easily pass through the portion other than the recess of the salient pole portion, and the decrease in the magnetic resistance of the salient pole portion can be suppressed.

On the other hand, in the case where the rotor 20 (rotor) is a built-in rotor disposed outside the stator 10 (stator), the salient pole portion has a shape that becomes narrower as it is farther from the air gap. Therefore, the magnetic flux is less likely to pass through the salient pole portions than the external rotor. As a result, it is difficult to suppress a decrease in magnetic resistance of the salient pole portions as compared to an external rotor.

The above description has been given of the embodiment of the rotating electric machine according to the present invention, including the operational effects thereof. However, the rotating electric machine according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention described in the claims.

The above embodiments are described in detail for the purpose of understanding the present invention, and the present invention is not limited to include all the structures described. Note that a part of the structure of one embodiment may be replaced with the structure of another embodiment, and the structure of another embodiment may be added to the structure of one embodiment. Further, other configurations may be added, deleted, and replaced to some configurations of the embodiments.

For example, in embodiment 3 described above, the corners of both ends at the width a of the salient pole portions 326 are obliquely cut. However, the corners of both ends at width a of salient pole portion 326 may also be cut in an arc shape.

Description of the reference symbols

4. Shaft

6. Rotor housing

10. Stator (stator)

20. Rotor (rotor)

100. 200, 300 rotating electrical machine (Motor)

102. Air gap

104. Trough

110. Stator magnet yoke

112. Armature winding

112A, 112B conductor

116. Tooth

116a waist part

116b flange portion

120. Rotor yoke

122. Permanent magnet

126. 226, 326 salient pole portions

228. 328, and a recess.

Claims (7)

1. A rotating electrical machine comprising:

an annular rotor having a plurality of permanent magnets and rotating about a rotating shaft; and an annular stator having a plurality of teeth facing the plurality of permanent magnets via gaps in a radial direction of the rotor, the rotating electrical machine being characterized in that,

a plurality of the permanent magnets are magnetized in the same direction along a radial direction of the rotor,

the rotor has a plurality of salient pole portions between adjacent ones of the permanent magnets,

a length in a circumferential direction of the rotor in the salient pole portions is longer than a length in the circumferential direction of the rotor in the teeth,

the distance between the salient pole portions and the teeth in the radial direction of the rotor is longer than the distance between the permanent magnets and the teeth in the radial direction of the rotor.

2. The rotating electric machine according to claim 1,

the salient pole portion has at least 1 or more concave portion on a surface facing the gap.

3. The rotating electric machine according to claim 2,

the cross section of the concave part, which is orthogonal to the rotating shaft, is formed into an arc shape, a polygon shape or a V shape.

4. A rotating electric machine according to claim 3,

the salient pole portions are cut obliquely at angles forming both ends of the rotor in the circumferential direction, or are cut in an arc shape.

5. The rotating electric machine according to any one of claims 1 to 3,

a length of the salient pole portions along a circumferential direction of the rotor is in a range of 180 degrees to 150 degrees at an electrical angle.

6. The rotating electric machine according to any one of claims 1 to 3,

the rotor has P magnetic poles, P is a natural number of 2 or more,

the number of the teeth of the stator is S, S is a natural number of more than 3,

the number of slots per phase per pole is 0.25 to 0.5.

7. The rotating electric machine according to any one of claims 1 to 3,

the rotor is disposed outside the stator.

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