Magnetic geared rotary electrical machine

Abstract

Provided is a magnetic geared rotary electric machine that can reduce torque ripple caused by a secondary component of an inductive voltage.　This magnetic geared rotary electric machine has: a stator that has a stator core, a coil, and a stator magnet; a first rotor (20) that is configured by arranging a plurality of magnetic pole pieces (21) in a circumferential direction; and a second rotor (10) that has a plurality of rotor magnets (12), wherein the magnetic pole pieces of the first rotor are configured in a circumferentially skewed structure, the stator magnet of the stator has a plurality of magnetic poles that are divided along the axial direction into a number of divisions corresponding to the skewed structure, and the polarities of magnetic poles that are neighboring in the axial direction are reversed.

Description

Magnetic-geared rotating electric motor

[0001] The present disclosure relates to a magnetic-geared rotating electric machine.

[0002] In recent years, magnetic-geared rotating electric machines of a magnetic flux modulation type have been researched and developed to achieve high torque density. In a magnetic-geared rotating electric machine, a high-speed rotor on the inner diameter side is rotated by a three-phase alternating current applied to a stator coil, and a low-speed rotor corresponding to the output shaft is rotated using the principle of magnetic gears. Unlike conventional rotating electric machines with a single rotor, a magnetic-geared rotating electric machine has two rotors and operates the two rotors using modulated magnetic flux, so various magnetic fluxes generate torque ripple. As a result, the torque ripple is larger than that of conventional rotating electric machines.

[0003] In magnetic gears, which share the same torque generation principle as magnetic-geared rotating electric machines, a structure has been proposed in which magnets provided in a high-speed rotor are continuously skewed in the axial direction to reduce the cogging torque generated in each component part in the axial direction of the magnetic gear (see, for example, Patent Document 1). Another conventional magnetic-geared rotating electric machine has been proposed with a structure that reduces cogging torque by changing the torque phase using multiple stage skews (see, for example, Patent Document 2).

[0004] International Publication No. 2015 / 053005 Patent No. 7179244

[0005] However, in conventional magnetic-geared rotating electric machines, although it is possible to reduce cogging torque, there is a problem in that it is not possible to reduce torque ripple.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a magnetic-geared rotating electric machine that can reduce torque ripple caused by the secondary component of induced voltage.

[0007] The magnetic-geared rotating electric machine of the present disclosure includes a stator having a stator core with multiple teeth, coils wound around the stator core, and stator magnets attached to the teeth, a first rotor having multiple pole pieces arranged circumferentially and attached to the stator via an air gap, and a second rotor having multiple rotor magnets arranged circumferentially and attached to the first rotor via an air gap, wherein the pole pieces of the first rotor are configured with a circumferential skew structure, and the stator magnet of the stator has multiple magnetic poles divided axially by a number of divisions corresponding to the skew structure, with the polarity of adjacent magnetic poles being reversed in the axial direction.

[0008] In the magnetic-geared rotating electric machine disclosed herein, the pole pieces of the first rotor are configured with a circumferential skew structure, the stator magnet of the stator has multiple magnetic poles divided along the axial direction by a number of divisions corresponding to the skew structure, and the polarity of adjacent magnetic poles in the axial direction is reversed, thereby reducing torque ripple caused by the secondary component of the induced voltage.

[0009] 1 is a perspective view of a magnetic-geared rotating electric machine of Comparative Example 1 according to Embodiment 1. FIG. 2 is a cross-sectional view of the magnetic-geared rotating electric machine of Comparative Example 1 according to Embodiment 1. FIG. 3 is a diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 1 according to Embodiment 1. FIG. 4 is a characteristic diagram of the magnetic-geared rotating electric machine of Comparative Example 1 according to Embodiment 1. FIG. 5 is a table showing winding coefficients of secondary components of induced voltages in the magnetic-geared rotating electric machines of Comparative Examples 1 to 4 according to Embodiment 1. FIG. 6 is a cross-sectional view of a magnetic-geared rotating electric machine of Comparative Example 2 according to Embodiment 1. FIG. 7 is a diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 2 according to Embodiment 1. FIG. 8 is a characteristic diagram of the magnetic-geared rotating electric machine of Comparative Example 2 according to Embodiment 1. FIG. 9 is a cross-sectional view of a magnetic-geared rotating electric machine of Comparative Example 3 according to Embodiment 1. FIG. 10 is a diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 3 according to Embodiment 1. FIG. 11 is a characteristic diagram of the magnetic-geared rotating electric machine of Comparative Example 3 according to Embodiment 1. FIG. 12 is a cross-sectional view of a magnetic-geared rotating electric machine of Comparative Example 4 according to Embodiment 1. FIG. 13 is a diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 4 according to Embodiment 1. 1. A characteristic diagram of a magnetic-geared rotating electric machine of Comparative Example 4 related to Embodiment 1. A perspective view of the magnetic-geared rotating electric machine of Embodiment 1 with the stator removed. A cut-away perspective view of the stator of the magnetic-geared rotating electric machine of Embodiment 1. A diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Embodiment 1. A characteristic diagram of the magnetic-geared rotating electric machine of Embodiment 1. A diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Embodiment 1. A characteristic diagram of the magnetic-geared rotating electric machine of Embodiment 1. A diagram showing a cogging torque waveform in the magnetic-geared rotating electric machine of Comparative Example 5 related to Embodiment 2. A characteristic diagram of the magnetic-geared rotating electric machine of Comparative Example 5 related to Embodiment 2. A diagram showing a cogging torque waveform in the magnetic-geared rotating electric machine of Embodiment 2. A characteristic diagram of the magnetic-geared rotating electric machine of Embodiment 2. A diagram showing a transmission torque waveform in the magnetic-geared rotating electric machine of Comparative Example 6 related to Embodiment 3. A diagram showing a transmission torque waveform in the magnetic-geared rotating electric machine of Embodiment 3. A cut-away perspective view of the magnetic-geared rotating electric machine of Embodiment 4.Fig. 10 is a cutaway perspective view of a stator of a magnetic-geared rotating electric machine according to embodiment 4. Fig. 11 is a view for explaining the structure of a low-speed rotor of a magnetic-geared rotating electric machine according to embodiment 5. Fig. 12 is a cross-sectional view of a magnetic-geared rotating electric machine according to embodiment 6. Fig. 13 is a cutaway perspective view of a stator of a magnetic-geared rotating electric machine according to embodiment 6.

[0010] Hereinafter, a magnetic-geared rotating electric machine according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the same reference numerals in the various drawings indicate the same or corresponding parts.

[0011] The structure of the magnetic-geared rotating electric machine in this disclosure will be described as the structure of a magnetic-geared motor or magnetic-geared generator in which a high-speed rotor as a second rotor, a low-speed rotor as a first rotor, and a stator are assembled in this order from the inner diameter side to the outer diameter side. Alternatively, a structure in which a stator, a low-speed rotor, and a high-speed rotor are assembled in this order from the inner diameter side to the outer diameter side may be used.

[0012] First Embodiment As will be described later, a magnetic-geared rotating electric machine according to a first embodiment for implementing the present disclosure applies stage skew to a low-speed rotor and divides the stator magnets of the stator in the axial direction to correspond to the stage skew of the low-speed rotor. First, a comparative magnetic-geared rotating electric machine in which stage skew or the like is not applied to the low-speed rotor will be described. Furthermore, the magnetic-geared rotating electric machine for implementing the present disclosure will be described as being driven by three-phase AC current.

[0013] FIG. 1 is a perspective view of a magnetic-geared rotating electric machine of Comparative Example 1 according to the first embodiment. FIG. 1 shows the exterior of the magnetic-geared rotating electric machine 1 of Comparative Example 1. This magnetic-geared rotating electric machine 1 is configured, in order from the inner diameter side, with a high-speed rotor 10 having rotor magnets 12 on the surface of a cylindrical rotor core 11, a low-speed rotor 20 composed of a plurality of magnetic pole pieces 21, and a stator 30 in which stator magnets 32 are incorporated into the teeth of a stator core 31 and coils 33 are wound around them. The high-speed rotor 10, the low-speed rotor 20, and the stator 30 are arranged coaxially with gaps interposed between them. The direction parallel to the central axis of rotation of the high-speed rotor 10 and the low-speed rotor 20 is referred to as the axial direction, the direction perpendicular to the central axis of rotation is referred to as the radial direction, and the direction of rotation around the central axis of rotation is referred to as the circumferential direction. The inner diameter side refers to the direction radially approaching the central axis of rotation, and the outer diameter side refers to the direction radially away from the central axis of rotation.

[0014] Stator magnets 32 are incorporated into the tips of the teeth of the stator core 31, forming a consequent pole structure. A consequent pole structure is a structure in which the polarity of the stator magnets 32 is the same across the air gap, the magnetization direction is along the radial direction, and the teeth of the stator core 31 have the opposite polarity to the stator magnets 32. Note that the magnetization direction of the stator magnets 32 is not limited to along the radial direction, and may be parallel orientation, polar anisotropic orientation, or the like, as long as magnetic flux flows in and out on the surface of the stator magnet 32 ​​facing the air gap.

[0015] Figure 2 is a cross-sectional view in a direction perpendicular to the axial direction of the magnetic-geared rotating electric machine of Comparative Example 1 shown in Figure 1. The number of pole pairs in the high-speed rotor 10 is 6, the number of pole pieces in the low-speed rotor 20 is 24, and the number of teeth in the stator 30 is 18. Therefore, the reduction ratio between the high-speed rotor 10 and the low-speed rotor 20 is 4, which is 24 divided by 6.

[0016] Fig. 3 is a diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 1 shown in Fig. 1. In Fig. 3, the horizontal axis represents the rotation angle, and the vertical axis represents the induced voltage. Note that the horizontal axis also shows the electrical angle. In Fig. 3, the solid line represents the induced voltage of the U phase, the dashed line represents the induced voltage of the V phase, and the dashed-dotted line represents the induced voltage of the W phase. The induced voltage waveform shown in Fig. 3 is obtained when the rotation speed of the high-speed rotor 10 is 60 rpm and the rotation speed of the low-speed rotor 20 is 15 rpm since the reduction ratio is 4.

[0017] FIG. 4 is a characteristic diagram obtained by frequency analysis of the induced voltage waveform shown in FIG. 3 . In FIG. 4 , the horizontal axis represents the order and the vertical axis represents the induced voltage. The vertical axis represents the induced voltage normalized to the fundamental wave component of 1. From FIG. 4 , it can be seen that the magnetic-geared rotating electric machine of Comparative Example 1 generates a second-order component of the induced voltage that is not generated in a rotating electric machine with a single rotor. This second-order component of the induced voltage is caused by a modulation wave magnetic flux generated by the magnetomotive force of the rotor magnet of the high-speed rotor and the magnetic flux modulation of the permeance of the low-speed rotor. The magnetic flux modulation between the high-speed rotor and the low-speed rotor generates a fundamental wave magnetic flux of six pole pairs, a modulation wave magnetic flux of 24-6 = 18 pole pairs, and a modulation wave magnetic flux of 24 + 6 = 30 pole pairs. First, the fundamental wave magnetic flux of the six pole pairs is the fundamental wave component of the induced voltage. Furthermore, the modulation wave magnetic flux of 18 pole pairs does not rotate even when the two rotors rotate. The reason for this is that in a stator with 18 pole pairs, coupling is required with stator magnets with 18 pole pairs.

[0018] On the other hand, the modulated wave magnetic flux of the 30 pole pairs interlinks with the coil at twice the frequency of the fundamental wave. Therefore, the modulated wave magnetic flux of the 30 pole pairs generates an induced voltage with twice the frequency of the fundamental wave, i.e., a secondary induced voltage per one electrical angle cycle. Here, if the induced voltage of the fundamental wave is generated in the order of U phase, V phase, and W phase, the secondary induced voltage is generated in the order of U phase, W phase, and V phase, so the torque ripple due to the secondary induced voltage is generated as a third-order component per one electrical angle cycle.

[0019] 5 is a table showing the winding factor of the secondary component of the induced voltage for different combinations of the ratios between the number of pole pairs of the high-speed rotor, the number of pole pieces of the low-speed rotor, and the number of stator teeth in the magnetic-geared rotating electric machines of Comparative Examples 1 to 4, including Comparative Examples 2 to 4 described below. Figure 5 shows four combinations of the ratios between the number of pole pairs of the high-speed rotor, the number of pole pieces of the low-speed rotor, and the number of stator teeth. The winding factor is given by the product of the short-pitch winding factor and the distributed winding factor. The short-pitch winding factor represents the rate of reduction in the induced voltage caused by the difference between the winding pitch and the magnet pole pitch, while the distributed winding factor represents the rate of reduction in the induced voltage caused by the phase difference between multiple windings connected in series within one phase. 5 shows that a secondary component of the induced voltage occurs when the ratio of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth is 1:4:3 and 4:13:9, but does not occur when the ratio of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth is 5:17:12 and 7:25:18. However, as will be described later, the absence of a secondary component of the induced voltage when the ratio of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth is 5:17:12 and 7:25:18 is limited to when coils of the same phase are connected in series.

[0020] 1 and 2, the ratio of the number of pole pairs of the high-speed rotor to the number of magnetic pole pieces of the low-speed rotor to the number of stator teeth is 1:4:3, so the winding coefficient of the secondary component of the induced voltage is 0.866, which is very large. As a result, a large secondary component is generated relative to the fundamental wave component, as shown in FIG.

[0021] Figure 6 is a cross-sectional view of a magnetic-geared rotating electric machine of Comparative Example 2 according to this embodiment. As shown in Figure 6, this magnetic-geared rotating electric machine 1 is a magnetic-geared rotating electric machine in which the high-speed rotor 10 has 8 pole pairs, the low-speed rotor 20 has 26 pole pieces, and the stator 30 has 18 teeth. The ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 4:13:9. The reduction ratio is 3.25, which is 13 divided by 4.

[0022] Fig. 7 is a diagram showing an induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 2 shown in Fig. 6. In Fig. 7, the horizontal axis represents the rotation angle, and the vertical axis represents the induced voltage. Note that the horizontal axis also shows the electrical angle. In Fig. 7, the solid line represents the induced voltage of the U phase, the dashed line represents the induced voltage of the V phase, and the dashed-dotted line represents the induced voltage of the W phase. The induced voltage waveform shown in Fig. 7 is obtained when the rotation speed of the high-speed rotor 10 is 60 rpm and the rotation speed of the low-speed rotor 20 is 18.5 rpm because the reduction ratio is 3.25.

[0023] Fig. 8 is a characteristic diagram obtained by frequency analysis of the induced voltage waveform shown in Fig. 7. In Fig. 8, the horizontal axis represents the order and the vertical axis represents the induced voltage. The vertical axis represents the induced voltage normalized with the induced voltage of the fundamental wave component set to 1. Fig. 8 shows that in the magnetic-geared rotating electric machine of Comparative Example 2, a second-order component is included in the induced voltage, but it is very small compared to the fundamental wave component. This is a reasonable result considering that in Fig. 5, when the ratio of the number of pole pairs of the high-speed rotor: the number of magnetic pole pieces of the low-speed rotor: the number of stator teeth is 4:13:9, the winding coefficient of the second-order component of the induced voltage is 0.061.

[0024] Fig. 9 is a cross-sectional view of a magnetic-geared rotating electric machine of Comparative Example 3 according to the present embodiment. As shown in Fig. 9, this magnetic-geared rotating electric machine 1 is a magnetic-geared rotating electric machine in which the high-speed rotor 10 has five pole pairs, the low-speed rotor 20 has 17 pole pieces, and the stator 30 has 12 teeth. In other words, the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 5:17:12. The reduction ratio is 3.4, which is 17 divided by 5.

[0025] Fig. 10 is a diagram showing the induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 3 shown in Fig. 9. In Fig. 10, the horizontal axis represents the rotation angle, and the vertical axis represents the induced voltage. Note that the horizontal axis also shows the electrical angle. In Fig. 10, the solid line represents the induced voltage of the U phase, the dashed line represents the induced voltage of the V phase, and the dashed-dotted line represents the induced voltage of the W phase. The induced voltage waveform shown in Fig. 10 is obtained when the rotation speed of the high-speed rotor 10 is 60 rpm and the rotation speed of the low-speed rotor 20 is 17.6 rpm because the reduction ratio is 3.4.

[0026] Fig. 11 is a characteristic diagram obtained by frequency analysis of the induced voltage waveform shown in Fig. 10. In Fig. 11, the horizontal axis represents the order and the vertical axis represents the induced voltage. The vertical axis represents the induced voltage normalized with the induced voltage of the fundamental wave component set to 1. Fig. 11 shows that the induced voltage waveform of the magnetic-geared rotating electric machine of Comparative Example 3 does not contain a second-order component. This is a reasonable result considering that in Fig. 5, when the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 5:17:12, the winding coefficient of the second-order component of the induced voltage is 0.

[0027] Fig. 12 is a cross-sectional view of a magnetic-geared rotating electric machine of Comparative Example 4 according to this embodiment. As shown in Fig. 12, this magnetic-geared rotating electric machine 1 is a magnetic-geared rotating electric machine in which the high-speed rotor 10 has 7 pole pairs, the low-speed rotor 20 has 25 pole pieces, and the stator 30 has 18 teeth. The ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 7:25:18. The reduction ratio is 3.57, which is 25 divided by 7.

[0028] Fig. 13 is a diagram showing the induced voltage waveform in the magnetic-geared rotating electric machine of Comparative Example 4 shown in Fig. 12. In Fig. 13, the horizontal axis represents the rotation angle, and the vertical axis represents the induced voltage. Note that the horizontal axis also shows the electrical angle. In Fig. 13, the solid line represents the induced voltage of the U phase, the dashed line represents the induced voltage of the V phase, and the dashed-dotted line represents the induced voltage of the W phase. The induced voltage waveform shown in Fig. 13 is obtained when the rotation speed of the high-speed rotor 10 is 60 rpm and the rotation speed of the low-speed rotor 20 is 16.8 rpm because the reduction ratio is 3.57.

[0029] Fig. 14 is a characteristic diagram obtained by frequency analysis of the induced voltage waveform shown in Fig. 13. In Fig. 14, the horizontal axis represents the order and the vertical axis represents the induced voltage. The vertical axis represents the induced voltage normalized with the induced voltage of the fundamental wave component set to 1. Fig. 14 shows that the induced voltage waveform of the magnetic-geared rotating electric machine of Comparative Example 4 does not contain a second-order component. This is a reasonable result considering that in Fig. 5, when the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 7:25:18, the winding coefficient of the second-order component of the induced voltage is 0.

[0030] As described above, due to the magnetomotive force of the magnet of the high-speed rotor and the magnetic flux modulation of the permeance of the low-speed rotor, a secondary component of the induced voltage is generated when the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 1:4:3 and 4:13:9.

[0031] The combinations where the ratios of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth are 1:4:3 and 4:13:9 were chosen because they have a high winding coefficient x reduction ratio, which is an indicator of torque density, and are practical. When the ratio of the number of stator teeth is odd in the combination of the ratio of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth, a secondary component of the induced voltage is always generated. For example, in a magnetic-geared rotating electric machine with 14 pole pairs of the high-speed rotor, 44 pole pieces of the low-speed rotor, and 30 stator teeth, the ratio of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth is 7:22:15, and because the ratio of the number of teeth is odd, a secondary component of the induced voltage is generated. Furthermore, even when the ratio of the number of stator teeth is an even number, for example, when the ratio of the number of pole pairs of the high-speed rotor to the number of pole pieces of the low-speed rotor to the number of stator teeth is 5:17:12 or 7:25:18 as shown in Figure 5, if coils of the same phase are connected in parallel, a circulating current will flow, generating a secondary component of the induced voltage. When coils of the same phase are connected in series, no circulating current will be generated, and no secondary component of the induced voltage will be generated. The magnetic-geared rotating electric machine of this embodiment, which will be described below, can be applied to magnetic-geared rotating electric machines that generate a secondary component of the induced voltage.

[0032] Hereinafter, skew refers to dividing the pole pieces, magnets, or magnet magnetization into multiple stages in the axial direction and shifting each stage circumferentially. In a magnetic-geared rotating electric machine, applying skew to the high-speed rotor is generally considered to prevent the generation of secondary components of induced voltage. The skew angle required to reduce the secondary components of induced voltage is calculated as 360 electrical degrees based on the magnetic flux that generates the secondary components of induced voltage. However, applying a skew of 360 electrical degrees to a high-speed rotor would result in the fundamental component of the induced voltage becoming zero, and no torque would be generated. Therefore, skew cannot be applied to a high-speed rotor. In the magnetic-geared rotating electric machine of this embodiment, stage skew is applied to the low-speed rotor.

[0033] If the high-speed rotor has six pole pairs, the low-speed rotor has 24 pole pieces, and the stator has 18 teeth, the skew angle required to zero the secondary component of the induced voltage is 360 degrees in electrical angle, which translates to 360 / 24=15 degrees in mechanical angle. In this case, the fundamental wave magnetic flux of the induced voltage does not change whether or not the low-speed rotor is skewed. However, the modulated wave magnetic flux coupled with the stator magnet magnetic flux also shifts circumferentially depending on the skew. This causes the stator magnet and modulated wave magnetic flux to become uncoupled, and the low-speed rotor does not rotate in synchronization with the high-speed rotor. In the magnetic-geared rotating electric machine of this embodiment, the stator magnet is divided axially to correspond to the stage skew of the low-speed rotor, and the polarity is reversed. Alternatively, the magnetization direction of the stator magnet may be reversed axially without dividing the stator magnet axially.

[0034] FIG. 15 is a perspective view of a magnetic-geared rotating electric machine according to this embodiment, with the stator removed. FIG. 16 is a cutaway perspective view of the stator of the magnetic-geared rotating electric machine according to this embodiment. This magnetic-geared rotating electric machine has six pole pairs in the high-speed rotor, 24 pole pieces in the low-speed rotor, and 18 stator teeth. Like Comparative Examples 1 to 4, the magnetic-geared rotating electric machine according to this embodiment also has a stator core with a consequent pole structure. As shown in FIG. 15 , in the magnetic-geared rotating electric machine according to this embodiment, the pole pieces 21 of the low-speed rotor 20 are divided into two in the axial direction, and the two axially divided pole pieces 21 are offset from each other in the circumferential direction by half a pitch. In other words, a two-stage skew is applied to the low-speed rotor. Also, as shown in FIG. 16 , in the magnetic-geared rotating electric machine according to this embodiment, the stator magnet 32 ​​of the stator 30 is divided into two in the axial direction, and the two axially divided stator magnets are arranged to have different polarities.

[0035] In a magnetic-geared rotating electric machine configured in this manner, the fundamental wave magnetic flux generated by magnetic flux modulation between the high-speed rotor and the low-speed rotor does not change, but the modulated wave magnetic flux coupled with the stator magnet is shifted by 180 degrees electrical angle up and down in the axial direction. Therefore, by shifting the phase of the magnetic flux of the stator magnet by 180 degrees up and down in the axial direction, coupling with the modulated wave magnetic flux becomes possible. Shifting the phase of the magnetic flux by 180 degrees is equivalent to reversing the polarity.

[0036] Fig. 17 is a diagram showing induced voltage waveforms in the magnetic-geared rotating electric machine of the present embodiment shown in Figs. 15 and 16. In Fig. 17, the horizontal axis represents the rotation angle, and the vertical axis represents the induced voltage. Note that the horizontal axis also shows the electrical angle. In Fig. 17, the solid line represents the induced voltage of the U phase, the dashed line represents the induced voltage of the V phase, and the dashed-dotted line represents the induced voltage of the W phase. The induced voltage waveforms shown in Fig. 17 are obtained when the rotation speed of the high-speed rotor 10 is 60 rpm and the rotation speed of the low-speed rotor 20 is 15 rpm since the reduction ratio is 4.

[0037] FIG. 18 is a characteristic diagram obtained by frequency analysis of the induced voltage waveform shown in FIG. 17. In FIG. 18, the horizontal axis represents the order and the vertical axis represents the induced voltage. The vertical axis represents the induced voltage normalized with the induced voltage of the fundamental wave component set to 1. The magnetic-geared rotating electric machine of this embodiment has 6 pole pairs in the high-speed rotor, 24 pole pieces in the low-speed rotor, and 18 stator teeth. Comparing FIG. 4, which shows the characteristics of the magnetic-geared rotating electric machine of Comparative Example 1 in which a two-stage skew or the like is not applied to the low-speed rotor, with FIG. 18, which shows the characteristics of the magnetic-geared rotating electric machine of this embodiment, it can be seen that the second-order component of the induced voltage is almost zero in the magnetic-geared rotating electric machine of this embodiment.

[0038] Furthermore, when comparing Figure 3, which shows the characteristics of the magnetic-geared rotating electric machine of Comparative Example 1, with Figure 17, which shows the characteristics of the magnetic-geared rotating electric machine of this embodiment, it is clear that the amplitude of the fundamental wave component of the induced voltage is about 0.01 V in both cases, and therefore the application of two-stage skew to the low-speed rotor and the axial polarity reversal of the stator magnets does not change the amplitude of the fundamental wave component of the induced voltage, i.e., does not reduce the torque.

[0039] Next, as another magnetic-geared rotating electric machine according to this embodiment, in which the high-speed rotor has 8 pole pairs, the low-speed rotor has 26 pole pieces, and the stator has 18 teeth, a two-stage skew as shown in Fig. 15 is applied to the low-speed rotor, and a split stator magnet with opposite polarities in the axial direction is applied to the stator as shown in Fig. 16. In this other magnetic-geared rotating electric machine, the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 4:13:9.

[0040] Figure 19 is a diagram showing induced voltage waveforms in another magnetic-geared rotating electric machine of this embodiment. In Figure 19, the horizontal axis represents the rotation angle, and the vertical axis represents the induced voltage. Note that the horizontal axis also shows the electrical angle. In Figure 19, the solid line represents the induced voltage of the U phase, the dashed line represents the induced voltage of the V phase, and the dashed-dotted line represents the induced voltage of the W phase. The induced voltage waveforms shown in Figure 19 are obtained when the rotation speed of the high-speed rotor 10 is 60 rpm and the rotation speed of the low-speed rotor 20 is 15 rpm since the reduction ratio is 4.

[0041] FIG. 20 is a characteristic diagram obtained by frequency analysis of the induced voltage waveform shown in FIG. 19 . In FIG. 20 , the horizontal axis represents the order, and the vertical axis represents the induced voltage. The vertical axis represents the induced voltage normalized with the induced voltage of the fundamental wave component set to 1. In another magnetic-geared rotating electric machine of this embodiment, the high-speed rotor has 8 pole pairs, the low-speed rotor has 26 pole pieces, and the stator has 18 teeth. Comparing FIG. 8 , which shows the characteristics of the magnetic-geared rotating electric machine of Comparative Example 2 in which a two-stage skew or the like is not applied to the low-speed rotor, with FIG. 20 , which shows the characteristics of another magnetic-geared rotating electric machine of this embodiment, it can be seen that the second-order component of the induced voltage is almost zero in the other magnetic-geared rotating electric machine of this embodiment.

[0042] Furthermore, when comparing Figure 7, which shows the characteristics of the magnetic-geared rotating electric machine of Comparative Example 2, with Figure 19, which shows the characteristics of another magnetic-geared rotating electric machine of this embodiment, it is clear that the amplitude of the fundamental wave component of the induced voltage is about 0.01 V in both cases, and therefore the application of two-stage skew to the low-speed rotor and the axial polarity reversal of the stator magnets does not change the amplitude of the fundamental wave component of the induced voltage, i.e., does not reduce the torque.

[0043] As described above, the torque ripple caused by the secondary component of the induced voltage can be reduced by dividing the pole pieces of the low-speed rotor into multiple skewed stages offset by half a pitch in the circumferential direction, dividing the stator magnets in the axial direction by the same number of divisions as the stage skew, and reversing the polarity of adjacent divided stator magnets in the axial direction.

[0044] In this embodiment, magnetic-geared rotating electric machines with ratios of the number of pole pairs of the high-speed rotor, the number of magnetic pole pieces of the low-speed rotor, and the number of stator teeth of 1:4:3 and 4:13:9 have been mainly described, because the winding coefficient x reduction ratio, which is an indicator of torque density, is high. However, regardless of the magnetic-geared rotating electric machine with either combination, although the winding coefficient x reduction ratio is high, the cogging torque and torque ripple are large, and the applications to which it can be applied are limited.

[0045] As described in this embodiment, by dividing the pole pieces of the low-speed rotor into multiple skewed stages offset by half a pitch in the circumferential direction, dividing the stator magnets in the axial direction by the same number of divisions as the skewed stages, and reversing the polarity of adjacent divided stator magnets in the axial direction, it is possible to reduce to zero the secondary component of the induced voltage, which is the main cause of torque ripple, and to expand the range of applications to which magnetic-geared rotating electric machines can be applied.

[0046] Although the pole pieces of the low-speed rotor in the magnetic-geared rotating electric machine of this embodiment have a stepped skew structure, the pole pieces may also have a continuously skewed structure. In the case of continuously skewed pole pieces, it is sufficient to continuously skew the pole pieces by one pitch. Regarding the stator, the stator magnet may be divided into the axial direction by the number of possible divisions, and the polarity of adjacent stator magnets in the axial direction may be reversed. Alternatively, the stator magnet may be a ring magnet with one pole pair of continuously skewed magnetization, thereby reversing the axial polarity. Continuously skewed magnetization refers to a ring magnet in which north and south poles are alternately magnetized in the circumferential direction and the north and south poles are continuously inclined in the axial direction. Even if the pole pieces of the low-speed rotor have a continuously skewed structure, the secondary component of the induced voltage, which is a major cause of torque ripple, can be reduced to zero. Furthermore, by continuously skewing the pole pieces of the low-speed rotor, the cogging torque can be reduced more than with step-wise skew, and the range of applications to which magnetic-geared rotating electric machines can be applied can be expanded.

[0047] Embodiment 2. A magnetic-geared rotating electric machine according to embodiment 2 is a magnetic-geared rotating electric machine in which the high-speed rotor has 6 pole pairs, the low-speed rotor has 24 pole pieces, and the stator has 18 teeth. In the magnetic-geared rotating electric machine of this embodiment, the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 1:4:3. Like the magnetic-geared rotating electric machine of embodiment 1, the magnetic-geared rotating electric machine of this embodiment applies a two-stage skew as shown in FIG. 15 to the low-speed rotor and applies split stator magnets with different polarities in the axial direction as shown in FIG. 16 to the stator. In this embodiment, the effect of reducing cogging torque will be described.

[0048] First, we will explain the magnetic-geared rotating electric machine of Comparative Example 5, in which no two-stage skew or the like is applied to the low-speed rotor. In the magnetic-geared rotating electric machine of Comparative Example 5, the high-speed rotor also has 6 pole pairs, the low-speed rotor has 24 pole pieces, and the stator has 18 teeth. Figure 21 is a diagram showing the cogging torque waveform in the magnetic-geared rotating electric machine of Comparative Example 5. In Figure 21, the horizontal axis represents the rotation angle, and the vertical axis represents the cogging torque. Note that the horizontal axis also shows the electrical angle. In Figure 21, the solid line represents the cogging torque of the high-speed rotor, and the dashed line represents the cogging torque of the low-speed rotor.

[0049] FIG. 22 is a characteristic diagram obtained by frequency analysis of the cogging torque waveform shown in FIG. 21. In FIG. 22, the horizontal axis represents the order and the vertical axis represents the cogging torque. The cogging torque waveform in FIG. 21 includes a third-order component and its harmonic components per electrical angle cycle. The cogging torque of the high-speed rotor is the sum of the cogging torque between the high-speed rotor and the low-speed rotor and the cogging torque between the high-speed rotor and the stator. Since the high-speed rotor has two poles per electrical angle cycle and the low-speed rotor has four pole pieces, it can be seen that the cogging torque between the high-speed rotor and the low-speed rotor is composed of a third-order component and its harmonic components. In other words, since the north and south poles of the high-speed rotor maintain the same positional relationship as the pole pieces of the low-speed rotor, when the high-speed rotor rotates once, the low-speed rotor rotates 0.25 times, so the north pole of the high-speed rotor passes through 4 × (1 − 0.25) = 3 pole pieces of the low-speed rotor. Therefore, the cogging torque between the high-speed rotor and the low-speed rotor is mainly composed of a third-order component and its harmonic components.

[0050] Furthermore, because the high-speed rotor has one pole pair per electrical angle cycle and the stator has three pole pairs, the cogging torque between the high-speed rotor and the stator is composed of a third-order component, which is the least common multiple of 1 and 3, and its harmonic components. The cogging torque between the low-speed rotor and the stator is composed of a twelfth-order component, which is the least common multiple of 4 (the number of pole pieces in the low-speed rotor) and 6 (the number of poles in the stator magnet). However, since the low-speed rotor rotates only 0.25 times when the high-speed rotor rotates once, the cogging torque between the low-speed rotor and the stator, when considered based on the high-speed rotor, is 12 × 0.25 = third-order component. From these facts, it can be seen that the cogging torque of the high-speed rotor and the cogging torque of the low-speed rotor in the magnetic-geared rotating electric machine of Comparative Example 5 are both composed of a fundamental-order third-order component and its harmonic components.

[0051] Figure 23 is a diagram showing the cogging torque waveform in the magnetic-geared rotating electric machine of this embodiment. In this magnetic-geared rotating electric machine, the ratio of the number of pole pairs in the high-speed rotor, the number of pole pieces in the low-speed rotor, and the number of teeth in the stator is 1:4:3, and the low-speed rotor is configured with a two-stage skew as shown in Figure 15, and the stator uses a divided stator magnet with polarities that differ in the axial direction as shown in Figure 16. In Figure 23, the horizontal axis represents the rotation angle, and the vertical axis represents the cogging torque. Note that the horizontal axis also shows the electrical angle. In Figure 23, the solid line represents the cogging torque of the high-speed rotor, and the dashed line represents the cogging torque of the low-speed rotor.

[0052] Fig. 24 is a characteristic diagram obtained by frequency analysis of the cogging torque waveform shown in Fig. 23. In Fig. 24, the horizontal axis represents the order and the vertical axis represents the cogging torque. Comparing Fig. 22 with Fig. 24, it can be seen that the magnetic-geared rotating electric machine of this embodiment can reduce the third-order component of the cogging torque to almost zero. However, because the magnetic-geared rotating electric machine of this embodiment applies a two-stage skew to the low-speed rotor, there is no reduction effect on even-number multiples of the third-order component, and only odd-number multiples of the third-order component (3rd, 9th, 15th, .... components) can be reduced.

[0053] The reason why two-stage skew reduces cogging torque is that magnetic flux with opposite magnetic field directions is generated at each stage, canceling out the cogging torque. With two-stage skew, the phase difference at each stage is 180 electrical degrees (π), and because the phase difference for even-numbered components is 2π, the magnetic flux has the same magnetic field direction at each stage and is not canceled out, whereas the phase difference for odd-numbered components is π, so the magnetic flux has the opposite magnetic field direction at each stage and is canceled out.

[0054] As described above, the magnetic-geared rotating electric machine of this embodiment can reduce the third-order component and its odd-multiple components of the cogging torque waveform, and is therefore also effective in reducing the cogging torque.

[0055] Embodiment 3. A magnetic-geared rotating electric machine according to embodiment 3 is a magnetic-geared rotating electric machine in which the high-speed rotor has 6 pole pairs, the low-speed rotor has 24 pole pieces, and the stator has 18 teeth. In the magnetic-geared rotating electric machine of this embodiment, the ratio of the number of pole pairs of the high-speed rotor: the number of pole pieces of the low-speed rotor: the number of stator teeth is 1:4:3. Like the magnetic-geared rotating electric machine of embodiment 1, the magnetic-geared rotating electric machine of this embodiment applies a two-stage skew as shown in FIG. 15 to the low-speed rotor and applies split stator magnets with different polarities in the axial direction as shown in FIG. 16 to the stator. In this embodiment, transmitted torque will be described.

[0056] First, a magnetic-geared rotating electric machine of Comparative Example 6, in which a two-stage skew or the like is not applied to the low-speed rotor, will be described. Fig. 25 is a diagram showing the transmitted torque waveform in the magnetic-geared rotating electric machine of Comparative Example 6. In Fig. 25, the horizontal axis is the rotation angle, and the vertical axis is the transmitted torque. Note that the horizontal axis also shows the electrical angle. In Fig. 25, the solid line represents the transmitted torque of the high-speed rotor, and the dashed line represents the transmitted torque of the low-speed rotor. Note that the transmitted torque waveform shown in Fig. 25 is a transmitted torque waveform obtained by rotating only the high-speed rotor while the low-speed rotor is fixed.

[0057] Figure 26 is a diagram showing a transmission torque waveform in a magnetic-geared rotating electric machine of this embodiment. In this magnetic-geared rotating electric machine, the ratio of the number of pole pairs in the high-speed rotor, the number of pole pieces in the low-speed rotor, and the number of teeth in the stator is 1:4:3, and the low-speed rotor is configured with a two-stage skew as shown in Figure 15, and the stator uses a split stator magnet with polarities that differ in the axial direction as shown in Figure 16. In Figure 26, the horizontal axis represents the rotation angle, and the vertical axis represents the transmission torque. Note that the horizontal axis also shows the electrical angle. In Figure 26, the solid line represents the transmission torque of the high-speed rotor, and the dashed line represents the transmission torque of the low-speed rotor.

[0058] 25 and 26, it can be seen that the maximum value of transmission torque does not decrease in the magnetic-geared rotating electric machine of this embodiment. Even if a two-stage skew is applied to the low-speed rotor and split stator magnets with different polarities in the axial direction are applied to the stator, as in the magnetic-geared rotating electric machine of this embodiment, the maximum transmission torque does not decrease. Furthermore, in the magnetic-geared rotating electric machine of this embodiment, torque ripple is also reduced for the same reasons as in embodiment 1.

[0059] Fourth Embodiment. Figure 27 is a cutaway perspective view of a magnetic-geared rotating electric machine according to a fourth embodiment. The high-speed rotor is omitted from Figure 27. As shown in Figure 27, in the magnetic-geared rotating electric machine of this embodiment, the pole pieces 21 of the low-speed rotor 20 are divided into three in the axial direction. The pole pieces 21 are composed of split pole pieces 21a and 21c located on the outer axial sides and split pole piece 21b located in the center axially. The axial lengths of split pole pieces 21a and 21c are half the axial length of split pole piece 21b. In other words, the pole piece 21 is divided into three pieces symmetrically about the axial center plane, with the division ratio being 1:2:1. The split pole pieces 21a and 21b are offset from each other by half a pitch in the circumferential direction, and the split pole pieces 21b and 21c are offset from each other by half a pitch in the circumferential direction.

[0060] FIG. 28 is a cutaway perspective view of a stator of a magnetic-geared rotating electric machine according to this embodiment. As shown in FIG. 28 , in this magnetic-geared rotating electric machine, the stator magnet 32 ​​of the stator 30 is divided into three parts in the axial direction. The stator magnet 32 ​​is composed of split stator magnets 32a and 32c located on the outer axial sides and split stator magnet 32b located in the center axially. The axial lengths of split stator magnets 32a and 32c are half the axial length of split stator magnet 32b. In other words, the stator magnet 32 ​​is divided into three parts symmetrically about the axial center plane, with the division ratio being 1:2:1. Adjacent split stator magnets in the axial direction have opposite polarities. For example, split stator magnets 32a and 32c have south poles on their inner diameter sides, and split stator magnet 32b has a north pole on its inner diameter side.

[0061] That is, in the magnetic-geared rotating electric machine of this embodiment, the pole pieces of the low-speed rotor are divided into multiple stage skews that are offset by half a pitch in the circumferential direction, and the stator magnets of the stator are composed of split stator magnets that are divided axially by the same number of divisions as the stage skew, and the polarities of the split stator magnets that are adjacent in the axial direction are reversed, while the polarities of the split stator magnets that are adjacent in the circumferential direction are the same.

[0062] The magnetic-geared rotating electric machine configured in this manner can reduce torque ripple caused by the secondary component of induced voltage, similar to the magnetic-geared rotating electric machine of embodiment 1. Furthermore, because the pole pieces of the low-speed rotor and the stator magnets of the stator are divided into three in the axial direction, the electromagnetic force in the axial direction can be reduced, thereby suppressing thrust vibration.

[0063] In the rotating electric machine of this embodiment, the pole pieces of the low-speed rotor and the stator magnets of the stator are divided into three in the axial direction, but they may be divided into four or more. Furthermore, if the polarities of the pole pieces of the low-speed rotor and the stator magnets of the stator are symmetrical about the axial center plane, thrust vibrations generated in the axial direction due to skew of the low-speed rotor can be canceled.

[0064] In the magnetic-geared rotating electric machine of this embodiment, a gap may be provided between axially adjacent stator magnet segments, or a non-magnetic material such as resin may be inserted between axially adjacent stator magnet segments. Because axially adjacent stator magnet segments have different polarities, there is a possibility that magnetic flux short-circuiting may occur between the poles. However, by providing a gap between adjacent stator magnet segments or inserting a non-magnetic material, magnetic flux short-circuiting can be suppressed.

[0065] Embodiment 5. Figure 29 is a diagram for explaining the structure of a low-speed rotor of a magnetic-geared rotating electric machine according to embodiment 5. In this embodiment, the structure of a low-speed rotor for supporting two-stage skewed pole pieces will be explained.

[0066] Because the skew angle of the low-speed rotor is 360 electrical degrees, the pole pieces of each stage are offset by half a pitch, leaving gaps between the circumferentially aligned pole pieces. Figure 29 is a side view of the low-speed rotor as seen from the outer diameter side. As shown in Figure 29, the low-speed rotor 20 of this embodiment has annular end rings 22 at both axial ends. Pole piece support members 23 are positioned between the end rings 22 and the pole pieces 21 in the gaps between the circumferentially aligned pole pieces of the two-stage skewed pole pieces 21. The pole pieces 21 are fixed to the end rings 22 by tightening the pole piece support members 23 to the end rings 22 with nuts 24. The pole piece support members 23 can be, for example, a stepped shaft.

[0067] In the low-speed rotor 20 configured in this manner, the pole pieces 21 are firmly fixed to the end rings 22. Furthermore, since the end rings 22 are provided at both axial ends, the strength and reliability of the low-speed rotor 20 can be ensured.

[0068] In this embodiment, a stepped shaft is used as the pole piece support member 23, but a simple shaft, collar, or bolt may be used as long as the necessary areas are insulated. The gaps around the pole piece support member 23 may be molded with resin or the like. Furthermore, the gaps between the circumferentially arranged pole pieces may be molded with resin without using a pole piece support member.

[0069] Furthermore, the pole pieces of the low-speed rotor may be fixed with gaps between the stepped skewed pole pieces, or a non-magnetic material such as resin may be disposed between the stepped skewed pole pieces of the low-speed rotor.

[0070] Sixth Embodiment Figure 30 is a cross-sectional view of a magnetic-geared rotating electric machine according to a sixth embodiment. As shown in Figure 30, the magnetic-geared rotating electric machine 1 of this embodiment is a magnetic-geared rotating electric machine in which the high-speed rotor 10 has six pole pairs, the low-speed rotor 20 has 15 pole pieces, the stator 30 has nine teeth, and the stator magnet 32 ​​has nine pole pairs. In this magnetic-geared rotating electric machine, the ratio of the number of pole pairs in the high-speed rotor: the number of pole pieces in the low-speed rotor: the number of pole pairs in the stator is 2:5:3. The reduction ratio is 2.5, which is 5 divided by 2.

[0071] In the magnetic-geared rotating electric machine according to this embodiment, similar to the magnetic-geared rotating electric machine shown in Figure 15 of embodiment 1, the pole pieces 21 of the low-speed rotor 20 are divided into two in the axial direction, and the two axially divided pole pieces 21 are arranged offset from each other by half a pitch in the circumferential direction.

[0072] 31 is a cutaway perspective view of a stator of a magnetic-geared rotating electric machine according to this embodiment. In the stator 30 of this embodiment, the stator magnet 32 ​​is divided into two axially, and the two axially divided stator magnet segments have different polarities, and adjacent circumferentially adjacent stator magnet segments also have different polarities.

[0073] The magnetic-geared rotating electric machine of this embodiment shown in Figure 30 does not have a stator magnet with a consequent pole structure. In a magnetic-geared rotating electric machine with such a structure, even if a two-stage skew is applied to the low-speed rotor and split stator magnets with different polarities in the axial direction are applied to the stator as shown in Figure 31, the maximum transmission torque does not decrease, as in the third embodiment, and torque ripple is reduced, as in the first embodiment.

[0074] In the magnetic-geared rotating electric machine of this embodiment, the pole pieces of the low-speed rotor and the stator magnets of the stator are each divided into two in the axial direction, but they may also be divided into three or more parts, as in embodiment 4. Also, in the magnetic-geared rotating electric machine of this embodiment, as shown in Fig. 30, an example has been shown in which the number of stator teeth and the number of pole pairs of the stator magnet are the same, but the number of stator teeth and the number of pole pairs of the stator magnet do not have to be the same.

[0075] In the magnetic-geared rotating electric machine of this embodiment, a gap may be provided between axially adjacent stator magnet segments, or a non-magnetic material such as resin may be inserted between axially adjacent stator magnet segments. Because axially adjacent stator magnet segments have different polarities, there is a possibility that magnetic flux short-circuiting may occur between the poles. However, by providing a gap between adjacent stator magnet segments or inserting a non-magnetic material, magnetic flux short-circuiting can be suppressed.

[0076] The various aspects of the present disclosure are described below as appendices. (Appendix 1) A magnetic-geared rotating electric machine including: a stator having a stator core with a consequent pole structure on which a plurality of teeth are formed, a coil wound around the stator core, and stator magnets attached to the teeth; a first rotor having a plurality of magnetic pole pieces arranged circumferentially and attached to the stator via an air gap; and a second rotor having a plurality of rotor magnets arranged circumferentially and attached to the first rotor via an air gap, wherein the magnetic pole pieces of the first rotor are divided into a plurality of circumferentially offset stage-wise skews, and the stator magnets of the stator are composed of split stator magnets divided axially by the same number of divisions as the stage-wise skews, and the polarities of the split stator magnets adjacent in the axial direction are reversed and the polarities of the split stator magnets adjacent in the circumferential direction are the same. (Supplementary Note 2) The magnetic-geared rotating electric machine according to Supplementary Note 1, characterized in that, in the ratio between the number of pole pairs of the second rotor, the number of pole pieces of the first rotor, and the number of teeth of the stator, the ratio of the number of teeth of the stator is odd. (Supplementary Note 3) The magnetic-geared rotating electric machine according to Supplementary Note 2, characterized in that the ratio between the number of pole pairs of the second rotor, the number of pole pieces of the first rotor, and the number of teeth of the stator is 1:4:3. (Supplementary Note 4) The magnetic-geared rotating electric machine according to Supplementary Note 2, characterized in that the ratio between the number of pole pairs of the second rotor, the number of pole pieces of the first rotor, and the number of teeth of the stator is 4:13:9. (Supplementary Note 5) The magnetic-geared rotating electric machine according to Supplementary Note 1, characterized in that, in the ratio between the number of pole pairs of the second rotor, the number of pole pieces of the first rotor, and the number of teeth of the stator, the ratio of the number of teeth of the stator is even, and the coils of the same phase are connected in series. (Supplementary Note 6) The magnetic-geared rotating electric machine according to any one of Supplementary Notes 1 to 5, characterized in that a gap is provided between the axially adjacent stator magnet segments, or a non-magnetic member is inserted between the axially adjacent stator magnet segments. (Supplementary Note 7) The magnetic-geared rotating electric machine according to any one of Supplementary Notes 1 to 6, characterized in that the pole pieces divided into a plurality of stage skews are symmetrical about a center plane in the axial direction.(Supplementary Note 8) The magnetic-geared rotating electric machine according to any one of Supplements 1 to 7, characterized in that the pole pieces divided into a plurality of skew stages are arranged at intervals in the axial direction. (Supplementary Note 9) The magnetic-geared rotating electric machine according to any one of Supplements 1 to 8, characterized in that the first rotor has end rings at both ends in the axial direction, and the pole pieces divided into a plurality of skew stages are fixed to the end rings by pole piece support members.

[0077] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0078] REFERENCE SIGNS LIST 1 Magnetic geared rotating electric machine, 10 High speed rotor, 11 Rotor core, 12 Rotor magnet, 20 Low speed rotor, 21 Pole pieces, 21a, 21b, 21c Split pole pieces, 22 End ring, 23 Pole piece support member, 24 Nut, 30 Stator, 31 Stator core, 32 Stator magnet, 32a, 32b, 32c Split stator magnet, 33 Coil.

Claims

1. A magnetic-geared rotating electric machine comprising: a stator having a stator core with multiple teeth, a coil wound around the stator core, and stator magnets installed on the teeth; a first rotor having multiple magnetic pole pieces arranged circumferentially and installed across a gap from the stator; and a second rotor having multiple rotor magnets arranged circumferentially and installed across a gap from the first rotor, wherein the magnetic pole pieces of the first rotor are configured with a circumferential skew structure, and the stator magnet of the stator has multiple magnetic poles divided along the axial direction by a number of divisions corresponding to the skew structure, and the polarity of adjacent magnetic poles in the axial direction is reversed.

2. A magnetic-geared rotating electric machine according to claim 1, characterized in that said magnetic pole pieces are divided into a plurality of skewed stages offset in the circumferential direction at a predetermined pitch.

3. A magnetic-geared rotating electric machine as described in claim 1 or 2, characterized in that the stator core has a consequent pole structure, and the multiple magnetic poles are composed of split stator magnets divided along the axial direction by a number of divisions corresponding to the skew structure, and the polarities of the split stator magnets adjacent in the axial direction are reversed while the polarities of the split stator magnets adjacent in the circumferential direction are the same.

4. A magnetic-geared rotating electric machine as described in claim 1, characterized in that the pole pieces are configured with a continuous skew that is offset at a predetermined pitch in the circumferential direction, and the multiple magnetic poles are configured with continuously skewed magnetized ring magnets that are offset at a predetermined pitch in the circumferential direction.

5. A magnetic-geared rotating electric machine as described in any one of claims 1 to 4, characterized in that the ratio of the number of pole pairs of the second rotor to the number of magnetic pole pieces of the first rotor to the number of teeth of the stator is an odd number.

6. A magnetic-geared rotating electric machine according to claim 5, characterized in that the ratio of the number of pole pairs of the second rotor, the number of magnetic pole pieces of the first rotor, and the number of teeth of the stator is 1:4:

3.

7. A magnetic-geared rotating electric machine according to claim 5, characterized in that the ratio of the number of pole pairs of the second rotor, the number of magnetic pole pieces of the first rotor, and the number of teeth of the stator is 4:13:

9.

8. A magnetic-geared rotating electric machine as described in any one of claims 1 to 4, characterized in that in the ratio between the number of pole pairs of the second rotor, the number of magnetic pole pieces of the first rotor, and the number of teeth of the stator, the ratio of the number of teeth of the stator is an even number, and the coils of the same phase are connected in series.

9. A magnetic-geared rotating electric machine as described in claim 3, characterized in that a gap is provided between axially adjacent said split stator magnets, or a non-magnetic member is inserted between said axially adjacent said split stator magnets.

10. A magnetic-geared rotating electric machine according to claim 2, wherein the pole pieces divided into a plurality of stage skews are symmetrical about a central plane in the axial direction.

11. A magnetic-geared rotating electric machine according to claim 2 or 10, characterized in that the pole pieces divided into a plurality of stage skews are arranged at intervals in the axial direction.

12. A magnetic-geared rotating electric machine as described in any one of claims 1 to 11, characterized in that the first rotor has end rings at both axial ends, and the pole pieces are fixed to the end rings by pole piece support members.

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