JP2016220382A - Rotor of rotary electric machine, and rotary electric machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor of rotary electric machine that can obtain electromagnetic vibration sound reduction effect without increasing cogging torque and torque ripple.SOLUTION: A rotor 10 of a rotary electric machine having the number of poles N comprises a first rotor unit 101-1 and a second rotor unit 101-2 which are arranged in an axial direction of the rotor 10 by using the axial length center of the rotor 10 as a boundary. Magnet insertion holes for inserting permanent magnets 301a, 301b or a plurality of magnetic gaps 201 independently of magnet insertion grooves are formed in the first rotor unit 101-1 and the second rotor unit 101-2, the magnetic gaps 201 are formed at d-axis asymmetrical or q-axis asymmetrical positions so as to have periodicity of 2/N in a circumferential direction of the rotor 10, and relative positions in a circumferential direction of the first rotor unit 101-1 and the second rotor unit 101-2 are shifted by a prescribed angle θ which is larger than 0 degree and 90 degrees or less in an electric angle.SELECTED DRAWING: Figure 1(c)

Description

  The present invention relates to a rotor of a rotating electric machine and a rotating electric machine using the same.

  The rotating electrical machine is mounted on home appliances, various OA devices, and the like. In addition, the electrification of automobiles has been promoted, and many automobiles are installed as main machines (for HEV and EV) and auxiliary machines. Among them, electric power steering (EPS) and rotating electrical machines for compressors are required to have low cogging torque / low torque ripple and low vibration / low noise at the same time.

  EPS is a mechanism for assisting steering in an automobile. Steering is performed with hands that are particularly sensitive. Since steering is often performed in a state where the rotating electrical machine is not energized, the rotating electrical machine used for this is particularly required to have a low cogging torque. As a method for reducing cogging torque and torque ripple, for example, there is Patent Document 1.

  By the way, in-vehicle and compressor rotating electrical machines have a wide operating rotational speed range, and the excitation frequency of the electromagnetic excitation force varies within a wide range. When the excitation frequency of the electromagnetic excitation force matches the natural frequency of the rotating electrical machine or a device incorporating the rotating electrical machine, vibration and noise due to resonance occur. In the rotating electrical machine according to Patent Document 1 described above, such vibration and noise cannot be reduced.

The direction of the electromagnetic excitation force that causes vibration and noise generated from the rotating electrical machine main body is three directions: radial direction, tangential direction, and axial direction. In particular, in order to reduce noise in the audible band, in addition to the method of reducing the amplitude of these electromagnetic excitation forces (electromagnetic force harmonics), the amplitude of the electromagnetic force harmonics in the radial direction and the electrical angle phase in the axial direction There is a method of reducing vibration and noise caused by the radial excitation force by generating it in an appropriate pattern (for example, Patent Document 2).
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JP 2009-118739 A JP 2012-050274 A

  The demand for vibration and noise reduction is increasing due to the pursuit of a comfortable environment, and electric power steering (EPS) and rotating electrical machines for compressors are required to have low cogging torque and low torque ripple and low vibration and low noise at the same time.

  In the invention disclosed in Patent Document 2 described above, the opening portion, the coupling portion, and the outer peripheral thin portion are arranged together between the same magnetic poles in adjacent magnetic poles, the rotor core is divided into three in the axial direction, and one magnetic pole Vibration and noise caused by radial excitation force can be reduced by the method of laminating the layers by shifting them by a minute amount. However, the generation of cogging torque cannot be suppressed, but rather the cogging torque increases because the opening is formed in communication with the magnet insertion portion.

  Therefore, an object of the present invention is to provide a rotor of a rotating electrical machine that can simultaneously reduce vibration and noise without increasing cogging torque and torque ripple, and a rotating electrical machine using the rotor.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-described problems. For example, the rotor of a rotating electrical machine having N poles is arranged in the axial direction of the rotor with the center of the axial length of the rotor as a boundary. A first rotor unit and a second rotor unit, wherein the first rotor unit and the second rotor unit include a plurality of magnet insertion holes or magnet insertion grooves for inserting permanent magnets. A magnetic air gap is formed, and the magnetic air gap is formed at a position that is d-axis asymmetric or q-axis asymmetric so as to have a periodicity of 2 / N in the circumferential direction of the rotor, and the first rotor unit and The relative position in the circumferential direction of the second rotor unit is shifted by a predetermined angle θ that is greater than 0 degree and less than or equal to 90 degrees in electrical angle.

  ADVANTAGE OF THE INVENTION According to this invention, the rotor of the rotary electric machine which can acquire an electromagnetic vibration noise reduction effect, without increasing a cogging torque and a torque ripple, and a rotary electric machine using the same can be provided. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an external perspective view of a rotor 10 of a rotating electrical machine according to a first embodiment. FIG. 3 is a developed perspective view of a permanent magnet 301 constituting the rotor 10. It is a figure which shows typically arrangement | positioning of the permanent magnet in a rotor. It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of the rotor core piece 11a. It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of the rotor core piece 11b. It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of the rotor core piece 11c. It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of 11 d of rotor core pieces. It is a figure for demonstrating the eigenmode of a stator core. It is a figure which shows the example of the annular mode in a cross section perpendicular | vertical to the rotating shaft of a stator core. It is a figure which shows the example of the axial direction mode in the cross section which passes along the rotating shaft of a stator core. It is a figure which shows the natural mode used as the combination of the circular mode 4th order and the axial mode 0th order. It is a figure which shows the natural mode used as the combination of the ring mode quartic and the axial mode primary. It is a figure which shows the natural mode used as the combination of the circular mode quaternary and the axial mode secondary. It is the figure which showed the calculation result of the radial direction 4th-order electromagnetic force harmonic in the prior art 1. FIG. It is an electrical angle phase difference of an excitation force pattern of time-secondary and space N / 2-order radial electromagnetic force harmonics in Prior Art 1. This is the electrical angle phase difference of the excitation force pattern of time-secondary and space N / 2-order radial electromagnetic force harmonics in Prior Art 2. It is an electrical angle phase difference of an excitation force pattern of time-secondary and space N / 2-order radial electromagnetic force harmonics in the present embodiment. It is the figure which showed the calculation result at the time of inputting the unit excitation force of time-secondary and radial direction space fourth order. It is a comparison figure of the acoustic power level in 4800 Hz. It is a comparison figure of an acoustic power level maximum value. It is sectional drawing which shows the rotary electric machine structure which concerns on 2nd Embodiment. It is sectional drawing which shows the rotary electric machine structure which concerns on 3rd Embodiment. It is sectional drawing which shows the rotary electric machine structure which concerns on 4th Embodiment. It is sectional drawing which shows the rotary electric machine structure which concerns on 5th Embodiment. It is sectional drawing which shows the rotary electric machine structure which concerns on 6th Embodiment.

  Hereinafter, embodiments of a rotating electrical machine according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is described about the same element and the overlapping description is abbreviate | omitted.

(First embodiment)
Fig.1 (a) shows the rotor 10 of the rotary electric machine which concerns on 1st Embodiment. FIG. 1B is a developed perspective view showing the arrangement positions of the permanent magnets 301 a and 301 b constituting the rotor 10. FIG. 1C corresponds to a diagram in which FIGS. 1A and 1B are overlapped, and is a perspective view schematically showing the arrangement positions of the permanent magnets 301a and 301b.

  The rotor 10 of this embodiment is an embodiment applied to a three-phase permanent magnet rotating electrical machine. The rotor 10 has an embedded magnet type 8-pole machine (number of poles N = 8, number of pole pairs N / 2 = 4). The rotor 10 includes a plurality of permanent magnets 301a and 301b and a rotor core 11 having a magnet insertion hole into which the permanent magnets 301a and 301b are inserted. The permanent magnet 301a and the permanent magnet 301b are arranged so that the polarities are alternately reversed. For example, when the outer diameter side of the permanent magnet 301a is an N pole, the outer diameter side of the permanent magnet 301b is an S pole.

  The rotor 10 is composed of two rotor units 101-1 and 101-2. The rotor units 101-1 and 101-2 are arranged side by side in the axial direction with the approximate center of the axial length of the rotor 10 as a boundary. Furthermore, the rotor unit 101-1 has two rotor core pieces 11 a and 11 b having a substantially center in the axial length as a boundary. Similarly, the rotor unit 101-2 includes two rotor core pieces 11c and 11d having a substantially axial center as a boundary.

  FIG. 2A is a cross-sectional view of the rotor core piece 11a cut along a cross section perpendicular to the axial direction. Similarly, FIG. 2B is a sectional view of the rotor core piece 11b, FIG. 2C is a sectional view of the rotor core piece 11c, and FIG. 2D is a sectional view of the rotor core piece 11d. As shown in FIG. 1C, the direction in which the permanent magnet 301b is arranged with respect to the rotation axis of the rotor 10 is defined as the x-axis direction and the y-axis direction, and the rotation axis direction of the rotor 10 is defined as the z-axis direction. 2A to 2D are cross-sectional views as seen from the z-axis direction. 2A to 2D are views in which the upper direction in the drawing is viewed as the x-axis direction.

  In each of the rotor core pieces 11a to 11d, a groove 201 constituting a magnetic gap is formed. The groove 201 is formed in the axial direction on the surface of the rotor core 11. The groove 201 is formed in the auxiliary salient pole portion between the permanent magnets 301a and 301b with a periodicity of 1/4 (= 2 / N) in the circumferential direction. The groove 201 is formed at a position that is asymmetric with respect to both the d-axis, which is an axis through which the magnetic flux passes through the center of the magnet, and the q-axis, which is an axis through which the magnetic flux flows between the poles.

  Between the rotor core piece 11a and the rotor core piece 11b, the position where the groove 201 serving as a magnetic gap is formed is shifted by one pole in the circumferential direction. With such a configuration, the electrical angle phase difference of the fourth-order electromagnetic harmonic having a spatial order of pole pair between the rotor core piece 11a and the rotor core piece 11b is 180 degrees (π). Similarly, the position where the groove 201 is formed is shifted by one pole in the circumferential direction between the rotor core piece 11c and the rotor core piece 11d. Between the rotor core piece 11c and the rotor core piece 11d, the electrical angle phase difference of the fourth-order electromagnetic harmonic having a spatial order of pole pair is 180 degrees (π).

  As shown in FIG. 1B and FIG. 1C, the permanent magnets 301a and 301b according to the present embodiment are divided into two in the axial direction with the approximate center of the axial length as a boundary. The two divided permanent magnets 301a and 301b are arranged with a skew angle θ in the circumferential direction with the approximate center of the axial length of the rotor 10 as a boundary surface. Here, the skew angle θ is an electrical angle that is larger than 0 degree and not larger than 90 degrees. Hereinafter, in the rotor 10 according to the present invention, the circumferential relative positions of the rotor unit 101-1 and the rotor unit 101-2 are represented by the skew angle θ with the permanent magnet 301a or 301b, and such a magnet arrangement Is represented as 1/2 skew.

  At this time, the rotor core piece 11c is arranged with a skew angle θ shifted in the circumferential direction with respect to the rotor core piece 11b. Further, the rotor core piece 11d is arranged with a skew angle θ shifted in the circumferential direction with respect to the rotor core piece 11a.

  The electromagnetic force harmonic is defined by equation (1). The electromagnetic force generated in the air gap determined by the three-dimensional electromagnetic field analysis includes harmonic components and is a function of time and space. When the electromagnetic force of a cross section perpendicular to the axial direction at a certain position in the axial direction (z-axis) is decomposed into radial, tangential, and axial components and each is expanded into a Fourier series in time and space, the following equation is obtained. .

  Each parameter in the equation (1) is as follows. σ is an electromagnetic force per unit area in the radial direction, tangential direction, or axial direction. n is a spatial order (mechanical angle). l is the rotation order (= time order × pole pair number). Anl is the amplitude of the spatial nth-order and rotational 1st-order harmonic components. ψ is a mechanical angle. ω is the fundamental angular frequency. t is time. φnl is the electrical angle phase of the spatial nth-order and rotational 1st-order harmonic components.

  FIG. 3A is a diagram for explaining the natural mode of the stator core 1. FIG. 3B is a diagram showing 0th-order and 4th-order annular modes as examples of the annular modes in a cross section perpendicular to the rotation axis of the stator core 1. FIG. 3C is a diagram showing zero-order, first-order, and second-order axial modes as examples of axial modes in a cross section passing through the rotation axis of the stator core 1.

  4 (a) to 4 (c) show an eigenmode of the fourth order of the circular ring whose order is the number of pole pairs (N / 2). FIG. 4A is a diagram illustrating an eigenmode that is a combination of a circular mode quaternary and an axial mode zero. FIG. 4B is a diagram showing an eigenmode that is a combination of a circular mode quaternary and an axial mode primary. FIG. 4C is a diagram showing an eigenmode that is a combination of an annular mode quaternary and an axial mode quadratic.

  The rotating electrical machine according to the present invention has an electrical component for a component in which the spatial order is a pole pair number among the radial harmonic components of the electromagnetic force generated in the air gap (that is, a quaternary component in the case of an 8-pole machine). The axial direction distribution of the angular phase difference is set to an excitation force pattern that hardly excites the eigenmodes shown in FIGS. 4 (a) to 4 (c).

  When the axial direction is the z-axis and the boundary condition of the stator core 1 is free at both ends, the radial displacement in the m-th order (m = 0, 1, 2) axial mode is d (m, z). Here, an excitation force pattern capable of suppressing the occurrence of the axial mode of m = 0 and 1 is considered. In order to simplify the examination, the structural system is only the stator core 1, and the axial length of the stator core 1 is L (−L / 2 ≦ z ≦ L / 2), which is the same as the axial length of the rotor core 11.

  Let f (z) be an excitation force pattern (hereinafter abbreviated as excitation force pattern) of radial electromagnetic force harmonics in a cross section passing through the rotation axis. Since the 0th-order axial mode of the stator core 1 is not excited, the conditional expression that the excitation force pattern f (z) needs to satisfy is the following expression in consideration of the condition that the skew angle θ ≠ 0. Note that Dmax is the radial amplitude.

  At this time, the primary axial mode of the stator core 1 is excited. In order to minimize the vibration amplitude, the conditional expression that the excitation force pattern f (z) needs to satisfy is as follows.

  Furthermore, the amplitude of the excitation force pattern f (z) is constant with the axial length L (−L / 2 ≦ z ≦ L / 2), and the constraint condition that the number of divisions of the rotor core 11 is 4 is introduced. The structure, that is, the ratio of the axial lengths of the rotor core pieces 11a, 11b, 11c, and 11d is the structure shown in FIG.

  Then, the reduction effect of the vibration and noise resulting from the radial direction excitation force in the rotary electric machine which concerns on this embodiment is demonstrated.

  FIG. 5 is a diagram showing a calculation result of the fourth-order electromagnetic force harmonics in the radial direction space of the rotating electrical machine having 8 poles and 12 slots. In FIG. 5, the electromagnetic force harmonic amplitude is made dimensionless based on the time-second harmonic amplitude. From FIG. 5, it can be seen that the time order that affects vibration and noise among the fourth-order electromagnetic force harmonics in the radial direction is -second order.

  FIG. 6A to FIG. 6C show the electrical angle phase difference of the excitation force pattern of the time-secondary and space N / 2-order radial electromagnetic force harmonics. FIG. 6A shows the electrical angle phase difference of the excitation force pattern of the radial electromagnetic force harmonics in a normal rotor structure not subjected to 1/2 skew or the like (hereinafter referred to as prior art 1). FIG. 6B shows the electrical angle phase difference of the excitation force pattern of the radial electromagnetic force harmonics when a 1/2 skew is applied to the rotor (hereinafter referred to as Conventional Technology 2). Here, the skew angle θ = 30 degrees. FIG. 6C shows the electrical angle phase difference of the excitation force pattern of the radial electromagnetic force harmonics in the rotor structure according to this embodiment. Here, the skew angle θ = 30 degrees.

  FIG. 7 shows time-secondary and radial space fourth-order unit excitation forces that affect vibration and noise on a rotating electrical machine having 8 poles and 12 slots having a rotor having the structure according to this embodiment. The calculation result of the sound power level when input is shown. In FIG. 7, it is a calculation result which set the acoustic power level maximum value in the prior art 1 to 0 dB.

  From FIG. 7, it can be seen that the sound power level at the maximum peak frequency is reduced in the 8-pole 12-slot machine according to the present embodiment as compared with the prior arts 1 and 2. From this, it can be seen that the rotating electrical machine according to the present embodiment has a noise reduction effect even in a frequency band of 5000 Hz or less.

  For reference, FIG. 7 shows a rotor structure in which a 2 / N periodic magnetic air gap is shifted by one pole and laminated in a ratio of 1: 2: 1 as shown in Patent Document 2. The sound power level when using is also shown (hereinafter referred to as Prior Art 3).

  FIG. 8 shows an acoustic power level difference at 4800 Hz (acoustic power level maximum peak frequency of prior art 1 shown in FIG. 7). The skew angle θ of the embodiment describes the calculation result changed in increments of 10 degrees from 10 to 90 degrees. The sound power level difference is −0.6 dB in the related art 2, while all the embodiments are about −25 dB.

  FIG. 9 shows the difference in the maximum sound power level. The sound power level difference is −0.6 dB in the related art 2, while the embodiment is about −5.1 to −8.1 dB.

  In human hearing, the difference between noise levels is 3 dB or more. From the results shown in FIGS. 7 to 9, it can be seen that the present embodiment has the same performance as the prior art 3 with respect to the effect of reducing vibration and noise.

  Here, the effect of reducing the cogging torque will be examined. In this embodiment, the magnetic gap provided independently of the magnet insertion hole of the rotor core 11 as shown in FIG. 2 or the like does not affect the cogging torque. In addition, as shown in FIG. 1B and the like, the permanent magnets 301a and 301b are arranged by shifting the skew angle θ with the approximate center of the axial length as a boundary, thereby minimizing the fundamental cogging torque. And torque ripple can be reduced.

  On the other hand, in the prior art 3, no consideration is given to the reduction of the cogging torque and the torque ripple, and the generation of the cogging torque is increased as compared with the prior art 1. According to the present embodiment, it is possible to reduce vibration and noise caused by electromagnetic force harmonics having a spatial order of the number of pole pairs in the radial direction that affect vibration and noise without deteriorating cogging torque and torque ripple.

(Second Embodiment)
FIG. 10 is a cross-sectional view showing a rotating electrical machine structure according to the second embodiment. In the present embodiment, this is a 16 pole 24 slot machine embedded magnet type rotating electrical machine.

  In the present embodiment, as the magnetic air gap, the d-axis asymmetrical and q-axis symmetric magnetic air gaps 201a and 201b having a periodicity of 2 / N are provided at the auxiliary salient pole portions between the permanent magnets 301a and 301b in the rotor core 11. The hole which comprises is provided.

(Third embodiment)
FIG. 11 is a cross-sectional view showing a rotating electrical machine structure according to the third embodiment. In the present embodiment, this is a 16 pole 24 slot machine embedded magnet type rotating electrical machine.

  In this embodiment, the magnetic air gap is asymmetrical with respect to both the d-axis and q-axis having a periodicity of 2 / N at the auxiliary salient pole portion between the permanent magnets 301a and 301b in the rotor core 11. Holes constituting the gap 201 are provided.

(Fourth embodiment)
FIG. 12 is a cross-sectional view showing a rotating electrical machine structure according to the fourth embodiment. In the present embodiment, this is a 16 pole 24 slot machine embedded magnet type rotating electrical machine.

  In the present embodiment, as the magnetic gap, the surface of the rotor core 11 is asymmetric with respect to both the d-axis and q-axis having a periodicity of 2 / N at the auxiliary salient pole portion between the permanent magnets 301a and 301b. A magnetic gap 201 is provided.

(Fifth embodiment)
FIG. 13 is a cross-sectional view showing a rotating electrical machine structure according to the fifth embodiment. In the present embodiment, this is a 16 pole 24 slot machine embedded magnet type rotating electrical machine.

  In the present embodiment, as the magnetic gap, the surface of the rotor core 11 has a d-axis symmetric and q-axis asymmetric magnetic gap 201a having a periodicity of 2 / N at the auxiliary salient pole portion between the permanent magnets 301a and 301b. 201b is provided.

(Sixth embodiment)
FIG. 14 is a cross-sectional view showing a rotating electrical machine structure according to the sixth embodiment. In this embodiment, it is a surface magnet type rotary electric machine of an 8-pole 12-slot machine.

  In this embodiment, the magnetic air gap is asymmetrical with respect to both the d-axis and q-axis having a periodicity of 2 / N at the auxiliary salient pole portion between the permanent magnets 301a and 301b in the rotor core 11. Holes constituting the gap 201 are provided.

  The rotor of the rotating electrical machine according to any of the above-described embodiments also reduces vibration and noise caused by electromagnetic harmonics having a spatial order of the number of pole pairs in the radial direction that affects vibration and noise while reducing cogging torque and torque ripple. As a result, vibration and noise of the rotating electrical machine can be reduced.

  The present invention is not limited to the number of phases, the number of poles, and the number of slots of the rotating electrical machine of the above-described embodiment. In the above-described embodiment, the concentrated winding rotary electric machine has been described. However, the invention can be applied not only to this but also to a distributed winding rotary electric machine. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

1: Stator core 1c: Cross section perpendicular to the axial direction of the stator core 1z: Cross section passing through the rotation axis of the stator core 10: Rotor 11: Rotor cores 11a, 11b, 11c, 11d: Rotor core pieces 101-1, 101-2: Rotor unit 201, 201a, 201b: Magnetic gaps 301, 301a, 301b: Permanent magnets σ: Electromagnetic force per unit area in the radial direction, tangential direction, or axial direction n: spatial order (mechanical angle)
l: rotational order (= time order x pole pair number)
Anl: Amplitude of spatial n-th order, rotational l-order harmonic component ψ: Mechanical angle ω: Fundamental angular frequency t: Time φnl: Electrical angle phase of spatial n-th order, rotational l-order harmonic component Dmax: Radial amplitude

Claims (8)

A rotor of a rotating electrical machine having N poles,
A first rotor unit and a second rotor unit disposed in the axial direction of the rotor with the center of the axial length of the rotor as a boundary;
The first rotor unit and the second rotor unit are formed with a plurality of magnetic air gaps independently of a magnet insertion hole for inserting a permanent magnet or a magnet insertion groove,
The magnetic air gap is formed at a position that is d-axis asymmetric or q-axis asymmetric so as to have a periodicity of 2 / N in the circumferential direction of the rotor,
A rotor of a rotating electrical machine in which the circumferential relative positions of the first rotor unit and the second rotor unit are shifted by a predetermined angle θ which is greater than 0 degree and less than 90 degrees in electrical angle. The rotor of the rotating electrical machine according to claim 1,
The first rotor unit and the second rotor unit are divided into a plurality of rotor core pieces in the axial direction,
The rotor core piece is laminated with the circumferential position of the magnetic gap shifted by one pole between adjacent rotor core pieces in the same rotor unit,
A rotor of a rotating electrical machine in which a circumferential position of the magnetic air gap is shifted by a predetermined angle θ between the first rotor unit and the second rotor unit. In the rotor of the rotating electrical machine according to claim 2,
The first rotor unit has a first rotor core piece and a second rotor core piece,
The second rotor unit has a third rotor core piece and a fourth rotor core piece,
The first rotor core piece to the fourth rotor core piece are rotors of a rotating electrical machine in which respective axial lengths are formed substantially the same. In the rotor of the rotating electrical machine according to any one of claims 1 to 3,
The rotor of a rotating electrical machine, wherein the magnetic gap is a groove formed on the surface of the rotor core. In the rotor of the rotating electrical machine according to any one of claims 1 to 3,
The rotor of a rotating electrical machine, wherein the magnetic gap is a hole formed in the rotor core. A rotor for a rotating electrical machine according to any one of claims 1 to 5,
A rotating electrical machine comprising the rotor and a stator disposed via a predetermined gap. The rotating electrical machine according to claim 6,
The slot formed in the stator is a rotating electrical machine formed so that a ratio between the number of poles of the rotor and the number of slots is 2: 3. A rotating electrical machine according to claim 6 or 7,
The stator is a rotating electrical machine that is a concentrated winding stator.

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