Stator structure in rotating electric machines

Abstract

To provide a stator structure in a rotary electric machine which can reduce the AC loss of the coil of a stator.SOLUTION: The stator structure in a rotary electric machine according to an embodiment includes an inside coil layer and an outside coil layer. In the inside coil layer, a plurality of coreless inside coils are arranged in a circumferential direction. In the outside coil layer, a plurality of coreless outside coils are arranged in a circumferential direction on the outside of the inside coil layers separately from the inside coils. The coil windings of the inside coils are formed of materials different from those of the coil windings of the outside coils.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a stator structure in a rotating electrical machine.

Background Art

[0002] Rotating electrical machines such as motors and generators include a stator and a rotor. In a motor, a rotating magnetic field is generated by applying a voltage to the coils of the stator. Then, the rotor is rotated by the generated rotating magnetic field, or an electromotive force is induced in the rotor by the rotating magnetic field, and the rotor is rotated by the induced electromotive force. Also, in a generator, a voltage (electromotive force) is induced in the coils of the stator by the rotating magnetic field generated by rotating the rotor. In such rotating electrical machines as motors and generators, from the viewpoint of weight reduction and the like, a coreless coil may be used as the stator coil. In this case, in the stator, a plurality of coreless coils are arranged side by side in the circumferential direction. The coils of a normal motor are provided with a core that serves as a path for the magnetic flux that links them, but there is a method that does not use a core. Generally, this method is called coreless (non-core), and a coil that adopts the coreless method is called a coreless coil. Since a coreless motor has no core, it is characterized by being lighter in weight than a normal motor.

[0003] As mentioned above, in rotating electric machines where coreless coils are used as stators, a magnetic field originating from the rotor is generated by magnets (permanent magnets) on the rotor or electromotive force induced in the rotor, and the magnetic flux originating from the rotor links with the stator coils. In the stator coils, AC losses such as eddy current losses and circulating current losses occur due to the linkage of the magnetic flux originating from the rotor. In rotating electric machines where coreless coils are used as stators, it is required to reduce the AC losses in the stator coils. For example, in electric motors where coreless coils are used as stators, it is required to increase the torque that rotates the rotor by reducing the AC losses in the stator coils. Also, in generators where coreless coils are used as stators, it is required to increase the voltage induced in the coils by reducing the AC losses in the stator coils. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 160047 / 1983 [Overview of the project] [Problems that the invention aims to solve]

[0005] The problem that this invention aims to solve is to provide a stator structure for a rotating electric machine that can reduce AC losses in the stator coils. [Means for solving the problem]

[0006] According to the embodiment, the stator structure in a rotating electric machine comprises an inner coil layer and an outer coil layer. The inner coil layer comprises a plurality of coreless inner coils, which are arranged circumferentially in the inner coil layer. The outer coil layer comprises a plurality of coreless outer coils, which are arranged circumferentially in the outer coil layer on the outer circumference of the inner coil layer without contacting the inner coils. In a rotating electric machine, the rotor is rotated by utilizing the rotating magnetic field generated by applying voltage to the inner and outer coils, or by inducing voltage in the inner and outer coils by the rotating magnetic field generated by the rotation of the rotor. Each coil winding of the inner coil is formed from a different material than each coil winding of the outer coil. In each of the first coils, which are positioned closer to the rotor than the inner and outer coils, the electrical resistance of the coil winding is higher than in each of the second coils, which are positioned further away from the rotor than the inner and outer coils. In each of the first coils, the coil pitch is larger than in each of the second coils. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic cross-sectional view showing the configuration of the electric motor according to the first embodiment, in a cross-section parallel or substantially parallel to the axial direction of the electric motor. [Figure 2] Figure 2 is a schematic diagram showing the configuration of the electric motor according to the first embodiment, viewed from one side in the axial direction of the electric motor. [Figure 3] Figure 3 is a schematic cross-sectional view showing the configuration of the electric motor according to the first embodiment, in a cross-section perpendicular or substantially perpendicular to the axial direction of the electric motor. [Figure 4] Figure 4 is a schematic perspective view showing any one of the inner coil and outer coil in the electric motor according to the first embodiment. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the drawings.

[0009] (First Embodiment) First, a first embodiment will be described as an example of an embodiment. In the first embodiment, an electric motor 1 will be described as an example of a rotating electric machine. Figures 1 to 3 show the configuration of the electric motor 1 according to the first embodiment. The electric motor 1 is, for example, a permanent magnet motor. As shown in Figures 1 to 3, the electric motor 1 comprises a rotor 2 and a stator 3. The rotor 2 is rotatable relative to the stator 3 about a rotation axis P.

[0010] In electric motor 1, the direction along the rotation axis P is defined as the axial direction (indicated by arrows A1 and A2). In electric motor 1, the direction around the rotation axis P is defined as the circumferential direction (indicated by arrows C1 and C2). In electric motor 1, the direction that intersects (is perpendicular or nearly perpendicular to) both the axial and circumferential directions is defined as the radial direction (indicated by arrows R1 and R2). In electric motor 1, the side approaching the rotation axis P in the radial direction is the inner circumference side, and the side moving away from the rotation axis P in the radial direction is the outer circumference side. Figure 1 schematically shows a cross-section of electric motor 1 parallel or nearly parallel to the axial direction. Figure 2 schematically shows the electric motor 1 viewed from one side in the axial direction, and Figure 3 schematically shows a cross-section of electric motor 1 perpendicular or nearly perpendicular to the axial direction.

[0011] In the example shown in Figures 1 to 3, the rotor 2 is positioned on the inner circumference side of the stator 3, which forms the stator structure of the electric motor 1. The stator 3 surrounds the rotor 2 from the outer circumference side of the electric motor 1, over its entire circumference in the circumferential direction. The rotor 2 is connected to the stator 3 in a manner that allows it to rotate around the axis of the rotation shaft P. The rotor 2 is connected to the stator 3 via bearings or the like (not shown).

[0012] In the example shown in Figures 1 to 3, the rotor 2 comprises a yoke 5 and a plurality of magnets (permanent magnets) 6. The central axis of the yoke 5 is coaxial with or approximately coaxial with the rotation axis P. In the rotor 2, each of the magnets 6 is fixed to the outer surface of the yoke 5, and the plurality of magnets 6 are arranged in a line on the outer surface of the yoke 5 in the circumferential direction of the motor 1. In the rotor 2, the plurality of magnets 6 arranged in the circumferential direction of the motor 1 form a ring shape or approximately ring shape with the rotation axis P as the center or approximately the center.

[0013] The stator 3 comprises an inner coil layer 7 and an outer coil layer 8. Each of the inner coil layer 7 and the outer coil layer 8 is formed in a ring shape or substantially ring shape with the rotation axis P as its center or substantially its center. Each of the inner coil layer 7 and the outer coil layer 8 surrounds the rotor 2 from the outer circumferential side of the motor 1 over the entire circumference in the circumferential direction of the motor 1. In the stator 3, the outer coil layer 8 is formed on the outer circumferential side of the motor 1 relative to the inner coil layer 7. The outer coil layer 8 surrounds the inner coil layer 7 from the outer circumferential side of the motor 1 over the entire circumference in the circumferential direction of the motor 1.

[0014] The inner coil layer 7 comprises a plurality of inner coils 11, and the outer coil layer 8 comprises a plurality of outer coils 12. In the inner coil layer 7, the plurality of inner coils 11 are arranged in a line in the circumferential direction of the electric motor 1. In the stator 3, the plurality of inner coils 11 arranged in the circumferential direction of the electric motor 1 form a ring shape or a substantially ring shape with the rotation axis P as the center or substantially center. In the outer coil layer 8, the plurality of outer coils 12 are arranged in a line in the circumferential direction of the electric motor 1. In the stator 3, the plurality of outer coils 12 arranged in the circumferential direction of the electric motor 1 form a ring shape or a substantially ring shape with the rotation axis P as the center or substantially center.

[0015] Due to the configuration described above, in the stator 3, multiple outer coils 12 are arranged in a line in the circumferential direction of the motor 1 on the outer circumference of the inner coil layer 7, which is composed of multiple inner coils 11. Therefore, the ring shape or substantially ring shape formed by the multiple outer coils 12 surrounds the ring shape or substantially ring shape formed by the multiple inner coils 11 from the outer circumference of the motor 1 over its entire circumference. In addition, each of the outer coils 12 has a gap between it and the inner coils 11 of the inner coil layer 7 in the radial direction of the motor 1. For this reason, each of the outer coils 12 is arranged so as not to be in contact with any of the inner coils 11.

[0016] Each of the inner coil 11 and the outer coil 12 is formed by winding coil wire. Each of the coil windings of the inner coil 11 and the outer coil 12 is conductive and is formed from, for example, a conductive metal. Furthermore, each of the inner coil 11 and the outer coil 12 is a coreless coil without an iron core. Therefore, the electric motor 1 is a coreless motor, etc., in which the inner coil 11 and the outer coil 12, which are the coils of the stator 3, are coreless.

[0017] In this embodiment, the rotor 2 is positioned on the inner circumference side of the stator 3. Of the two types of coils, the inner coil 11 and the outer coil 12, the inner coil 11 is the first coil, positioned closer to the rotor 2. The outer coil 12 is the second coil, positioned further away from the rotor 2.

[0018] In the electric motor 1, voltage can be applied to the inner coil 11 and the outer coil 12, and a magnetic field is generated by applying voltage to the inner coil 11 and the outer coil 12. By changing the magnetic field generated by the inner coil 11 and the outer coil 12 over time, such as by applying voltage to the inner coil 11 and the outer coil 12, the rotor 2 rotates around the axis of the rotation shaft P. Therefore, in this embodiment, the rotor 2 rotates due to the rotating magnetic field generated by applying voltage to the inner coil 11 and the outer coil 12.

[0019] In one example, three-phase power with different phases is supplied to the stator 3. In this case, as the inner coils 11, one or more inner coils 11U for the U phase, one or more inner coils 11V for the V phase, and one or more inner coils 11W for the W phase are provided respectively, and as the outer coils 12, one or more outer coils 12U for the U phase, one or more outer coils 12V for the V phase, and one or more outer coils 12W for the W phase are provided respectively. In one example such as FIGS. 1 to 3, two inner coils 11U, 11V, 11W are provided respectively, and two outer coils 12U, 12V, 12W are provided respectively. For this reason, the number of coils provided in the stator 3, that is, the total number of the inner coils 11 and the outer coils 12 is 12.

[0020] In the stator 3, the inner coil 11U and the outer coil 12U for the U phase are electrically connected in series or in parallel to each other via electrical wiring (not shown) or the like. Then, a voltage of the U phase is applied to the inner coil 11U and the outer coil 12U. Similarly, the inner coil 11V and the outer coil 12V for the V phase are electrically connected in series or in parallel to each other via electrical wiring (not shown) or the like, and a voltage of the V phase is applied to the inner coil 11V and the outer coil 12V. Then, the inner coil 11W and the outer coil 12W for the W phase are electrically connected in series or in parallel to each other via electrical wiring (not shown) or the like, and a voltage of the W phase is applied to the inner coil 11W and the outer coil 12W.

[0021] Note that, in one example, a rotating magnetic field is generated by applying a voltage to the inner coil 11 and the outer coil 12 as described above. Then, an electromotive force is induced in the rotor 2 by the generated rotating magnetic field, and the rotor 2 is rotated by the induced electromotive force. Therefore, in the electric motor 1, any configuration may be adopted as long as the rotor 2 is rotated by utilizing the rotating magnetic field generated by applying a voltage to the inner coil 11 and the outer coil 12 of the stator 3.

[0022] FIG. 4 shows either the inner coil 11 or the outer coil 12. Each of the inner coil 11 and the outer coil 12 has the same configuration as that shown in FIG. 4. As shown in FIG. 4 and the like, each of the inner coil 11 and the outer coil 12 has a winding axis B, and in each of the inner coil 11 and the outer coil 12, the coil winding is wound around the winding axis B. In an example of FIGS. 1 to 3 and the like, the winding axis B of each of the inner coil 11 and the outer coil 12 extends along the radial direction of the electric motor 1. Also, in each of the inner coil 11 and the outer coil 12, the number of turns N indicating the number of circumferences of the coil winding about the axis of the winding axis B is defined.

[0023] Each of the inner coil 11 and the outer coil 12 includes a pair of coil side portions 15, 16 and a pair of turning-back portions 17, 18. In each of the inner coil 11 and the outer coil 12, the coil side portions 15, 16 are spaced apart from each other in the circumferential direction of the electric motor 1, and a space 20 is formed between the coil side portions 15, 16 in the circumferential direction of the electric motor 1. For this reason, in each of the inner coil 11 and the outer coil 12, the coil side portion (first coil side portion) 15 is located on the opposite side of the coil side portion (second coil side portion) 16 across the space 20. In each of the inner coil 11 and the outer coil 12, the winding axis B extends through the space 20. Also, in each of the inner coil 11 and the outer coil 12, at each of the coil side portions 15, 16, the coil winding extends along the axial direction of the electric motor 1.

[0024] In each of the inner coil 11 and the outer coil 12, the folded portions 17 and 18 are located apart from each other in the axial direction of the electric motor 1, and the aforementioned space 20 through which the winding shaft B passes is formed between the folded portions 17 and 18 in the axial direction of the electric motor 1. Therefore, in each of the inner coil 11 and the outer coil 12, the folded portion (first folded portion) 17 is located on the opposite side of the space 20 from the folded portion (second folded portion) 18. In each of the inner coil 11 and the outer coil 12, the coil winding is folded back at each of the folded portions 17 and 18. Due to the above configuration, each of the inner coil 11 and the outer coil 12 is formed in a ring shape or a substantially ring shape in which the space 20 is surrounded around the entire circumference of the winding shaft B by the portion composed of the coil sides 15 and 16 and the folded portions 17 and 18.

[0025] When three-phase inner coils 11U, 11V, and 11W are provided in the inner coil layer 7, the V-phase inner coil 11V is positioned adjacent to each U-phase inner coil 11U on one side in the circumferential direction of the motor 1. The W-phase inner coil 11W is positioned adjacent to each U-phase inner coil 11U on the opposite side of the circumferential direction of the motor 1 from the V-phase inner coil 11V. In the example shown in Figures 1 to 3, six inner coils 11 are provided. In the inner coil layer 7, the winding axis B of each inner coil 11 is positioned at an angle of 60° or approximately 60° relative to the winding axis B of adjacent inner coils 11 in the circumferential direction of the motor 1.

[0026] Furthermore, when three-phase outer coils 12U, 12V, and 12W are provided in the outer coil layer 8, the V-phase outer coil 12V is positioned adjacent to each U-phase outer coil 12U on one side in the circumferential direction of the motor 1. Then, the W-phase outer coil 12W is positioned adjacent to each U-phase outer coil 12U on the opposite side of the circumferential direction of the motor 1 from the V-phase outer coil 12V. In addition, in the example shown in Figures 1 to 3, six outer coils 12 are provided. In the outer coil layer 8, the winding axis B of each outer coil 12 is positioned at an angle of 60° or approximately 60° relative to the winding axis B of adjacent outer coils 12 in the circumferential direction of the motor 1.

[0027] Furthermore, in this embodiment, each of the outer coils 12 constituting the outer coil layer 8 is positioned at an angular position offset from any of the inner coils 11 constituting the inner coil layer 7 in the circumferential direction of the motor 1. In the motor 1, one corresponding winding axis B of the outer coil 12 is positioned at an angular position between the winding axes B of two adjacent inner coils 11 in the circumferential direction. In one example, the winding axes B of two adjacent inner coils 11 are positioned at an angular θ offset from each other in the circumferential direction of the motor 1. The winding axis B of each of the two adjacent inner coils 11 is positioned at an angular θ / 2 offset in the circumferential direction of the motor 1 with respect to the winding axis B of the outer coil 12 positioned between the winding axes B of those two inner coils 11. When six inner coils 11 and six outer coils 12 are provided, as in the example shown in Figures 1 to 3, the angle θ is 60° or approximately 60°, and the angle θ / 2 is 30° or approximately 30°.

[0028] Furthermore, the inner coil layer 7 is provided with three-phase inner coils 11U, 11V, and 11W, and the outer coil layer 8 is provided with three-phase outer coils 12U, 12V, and 12W. In this case, each of the U-phase outer coils 12U is positioned in the inner coil layer 7 between adjacent V-phase inner coils 11V and W-phase inner coils 11W in the circumferential direction of the motor 1. Each of the V-phase outer coils 12V is positioned in the inner coil layer 7 between adjacent W-phase inner coils 11W and U-phase inner coils 11U in the circumferential direction of the motor 1. And each of the W-phase outer coils 12W is positioned in the inner coil layer 7 between adjacent U-phase inner coils 11U and V-phase inner coils 11V in the circumferential direction of the motor 1.

[0029] Furthermore, in this embodiment, each coil winding of the inner coil 11 is formed from a different material than each coil winding of the outer coil 12. Therefore, the electrical resistance of each coil winding of the inner coil 11 is different from the electrical resistance of each coil winding of the outer coil 12. And the electrical resistance of each coil winding of the inner coil 11 is higher than the electrical resistance of each coil winding of the outer coil 12.

[0030] In this embodiment, as described above, among the two types of coils, the inner coil 11 and the outer coil 12, the inner coil 11 is the first coil, positioned closer to the rotor 2, and the outer coil 12 is the second coil, positioned further away from the rotor 2. Therefore, each of the inner coils 11, which are the first coils, has a higher electrical resistance in its coil winding compared to each of the outer coils 12, which are the second coils. In one example, each of the outer coils 12, which are the second coils, is made of copper, while each of the inner coils 11, which are the first coils, is made of aluminum, which has an electrical resistance about 1.64 times that of copper.

[0031] In the inner coil layer 7, the electrical resistances of the coil windings of the multiple inner coils 11 may be the same as or different from each other. In the outer coil layer 8, the electrical resistances of the coil windings of the multiple outer coils 12 may be the same as or different from each other. However, in this example, even when the electrical resistances of the coil windings of the multiple inner coils 11 are different from each other, and when the electrical resistances of the coil windings of the multiple outer coils 12 are different from each other, the electrical resistance of each coil winding of the inner coil 11 is higher than the electrical resistance of each coil winding of the outer coil 12.

[0032] Furthermore, for each of the inner coil 11 and the outer coil 12, the central position E1 of the coil side portion 15 in the circumferential direction of the motor 1 is defined, and the central position E2 of the coil side portion 16 in the circumferential direction of the motor 1 is defined. Then, for each of the inner coil 11 and the outer coil 12, the angle between the central position E1 of the coil side portion 15 and the central position E2 of the coil side portion 16 in the circumferential direction of the motor 1 is defined as the coil pitch α.

[0033] In one example of this embodiment, the coil pitch α of each of the inner coil 11 and outer coil 12 is greater than or equal to the angle αref obtained by dividing 360°, which is the angle corresponding to the entire circumference, by the total number of inner coils 11 and outer coils 12. For example, in a configuration where the total number of inner coils 11 and outer coils 12 is 12, as shown in the example in Figures 1 to 3, the angle αref is 30°, and it is preferable that the coil pitch α of each of the inner coils 11 and outer coils 12 is 30° or greater.

[0034] Furthermore, the coil pitch α mentioned above is defined as the coil pitch α1 of each inner coil 11 and the coil pitch α2 of each outer coil 12. In one example of this embodiment, the coil pitch α1 of each inner coil 11 is different from the coil pitch α2 of each outer coil 12. Moreover, the coil pitch α1 of each inner coil 11 is larger than the coil pitch α2 of each outer coil 12. As described above, in this example, the coil pitch α of each of the inner coils 11, which are the first coils located closer to the rotor 2, is larger than that of each of the outer coils 12, which are the second coils located further away from the rotor 2.

[0035] In the inner coil layer 7, the coil pitches α1 of the multiple inner coils 11 may be the same or different from each other. In the outer coil layer 8, the coil pitches α2 of the multiple outer coils 12 may be the same or different from each other. However, in this example, even when the coil pitches α1 of the multiple inner coils 11 are different from each other, and when the coil pitches α2 of the multiple outer coils 12 are different from each other, the coil pitch α1 of each inner coil 11 is greater than the coil pitch α2 of each outer coil 12.

[0036] Furthermore, the number of turns N as described above is defined as the number of turns N1 for each inner coil 11 and the number of turns N2 for each outer coil 12. In one example of this embodiment, the number of turns N1 for each inner coil 11 is different from the number of turns N2 for each outer coil 12. And the number of turns N1 for each inner coil 11 is greater than the number of turns N2 for each outer coil 12. As described above, in this example, each of the inner coils 11, which are the first coils located closer to the rotor 2, has more turns N than each of the outer coils 12, which are the second coils located further away from the rotor 2.

[0037] In the inner coil layer 7, the number of turns N1 of the multiple inner coils 11 may be the same or different from each other. In the outer coil layer 8, the number of turns N2 of the multiple outer coils 12 may be the same or different from each other. However, in this example, even when the number of turns N1 of the multiple inner coils 11 are different from each other, and when the number of turns N2 of the multiple outer coils 12 are different from each other, the number of turns N1 of each inner coil 11 is greater than the number of turns N2 of each outer coil 12.

[0038] As described above, in this embodiment, the stator 3 has an outer coil layer 8 provided on the outer circumference of the inner coil layer 7, forming two coil layers. In the inner coil layer 7, a plurality of coreless inner coils 11 are arranged in a circumferential direction, and in the outer coil layer 8, a plurality of coreless outer coils 12 are arranged in a circumferential direction without contacting the inner coils 11. With this configuration, coils of the stator 3 are arranged in both the region close to the rotor 2 and the region far from the rotor 2.

[0039] Furthermore, in this embodiment, each coil winding of the inner coil 11 is formed from a different material than each coil winding of the outer coil 12. In the electric motor 1, which is a rotating electric machine, a magnetic field is generated by the rotor 2 due to magnets (permanent magnets) 6 etc. provided on the rotor 2, and the magnetic flux originating from the rotor 2 links the inner coil 11 and outer coil 12 of the stator 3. Also, in a configuration in which the rotor 2 is rotated by the electromotive force induced in the rotor 2, a magnetic field is generated due to the electromotive force induced in the rotor 2, and the magnetic flux originating from the rotor 2 links the inner coil 11 and outer coil 12 of the stator 3. As a result, AC losses such as eddy current losses and circulating current losses occur in the inner coil 11 and outer coil 12 of the stator 3 due to the linking of the magnetic flux originating from the rotor 2.

[0040] In this embodiment, where the rotor 2 is positioned on the inner circumference side of the stator 3, the amount of flux linkage caused by the rotor 2 increases in the inner coil 11, which is the first coil positioned closer to the rotor 2, and the influence of the flux caused by the rotor 2 becomes greater. In this embodiment, since the materials of the coil windings of the inner coil 11 and the outer coil 12 are different, it is possible to select a material for the inner coil 11 that can reduce the AC losses caused by the flux linkage caused by the rotor 2. This makes it possible to reduce the AC losses in the coils of the stator 3, including the inner coil 11.

[0041] Furthermore, in this embodiment, the electrical resistance of the coil windings is higher in each of the inner coils 11, which are the first coils located closer to the rotor 2, compared to each of the outer coils 12, which are the second coils located further away from the rotor 2. As a result, the AC losses caused by the linkage of magnetic flux originating from the rotor 2 are appropriately reduced in the inner coils 11, where the influence of magnetic flux originating from the rotor 2 is greater. In particular, by forming the coil windings of each of the inner coils 11, which are the first coils located closer to the rotor 2, from aluminum, which has a higher electrical resistance than copper, etc., the AC losses generated in the inner coils 11 are further appropriately reduced. In the electric motor 1, by reducing the AC losses generated in the coils of the stator 3, including the inner coils 11, the torque that rotates the rotor 2 is increased, and the torque characteristics of the electric motor 1 are improved.

[0042] Furthermore, the outer coil 12, which is the second coil located farther from the rotor 2, is less affected by the magnetic flux originating from the rotor 2. Therefore, even if the coil windings of the outer coil 12 are made from copper or a similar material with low electrical resistance, the AC losses in the outer coil 12 are reduced. As a result, the DC losses in the outer coil 12 are reduced due to the lower electrical resistance of the coil windings in each of the outer coils 12, and the DC losses generated in the coils of the stator 3, including the outer coil 12, are appropriately reduced. In the electric motor 1, by reducing the DC losses in the coils of the stator 3 in addition to the AC losses, the torque that rotates the rotor 2 is further increased, and the torque characteristics of the electric motor 1 are further improved.

[0043] Furthermore, in one example of this embodiment, the coil pitch α of the inner coil 11 and the outer coil 12 is greater than or equal to the angle αref obtained by dividing 360° by the total number of inner coils 11 and outer coils 12. As a result, the angular range occupied by the inner coil 11 and the outer coil 12 in the circumferential direction of the motor 1 increases, and the area occupied by the inner coil 11 and the outer coil 12 in the stator 3 increases. By increasing the area occupied by the inner coil 11 and the outer coil 12, it becomes possible to increase the amount of linked magnetic flux that links with the inner coil 11 and the outer coil 12 in the rotating magnetic field generated by applying voltage to the inner coil 11 and the outer coil 12 of the stator 3. In the motor 1, the amount of linked magnetic flux with the inner coil 11 and the outer coil 12 increases, further increasing the torque that rotates the rotor 2, and further improving the torque characteristics of the motor 1.

[0044] Furthermore, in one example of this embodiment, the coil pitch α is larger for each of the inner coils 11, which are the first coils located closer to the rotor 2, compared to each of the outer coils 12, which are the second coils located further away from the rotor 2. In a configuration where the rotor 2 is located on the inner circumference side relative to the stator 3, increasing the coil pitch α1 of each of the inner coils 11, which are the first coils located closer to the rotor 2, increases the amount of flux linkage with the coils (inner coils 11) at a position close to the rotor 2 in the generated rotating magnetic field. As a result, the torque that rotates the rotor 2 is further increased, and the torque characteristics of the electric motor 1 are further improved.

[0045] Furthermore, in one example of this embodiment, each of the inner coils 11, which are the first coils located closer to the rotor 2, has more turns N than each of the outer coils 12, which are the second coils located further away from the rotor 2. In a configuration where the rotor 2 is located on the inner circumference side relative to the stator 3, increasing the number of turns N1 of each of the inner coils 11, which are the first coils located closer to the rotor 2, makes it possible to appropriately increase the coil pitch α1 of each of the inner coils 11.

[0046] (modified version) In the embodiments described above, the rotor 2 is positioned on the inner circumference side of the stator 3. However, in one modified example, in the electric motor 1, the rotor 2 is positioned on the outer circumference side of the stator 3. In this case as well, the stator 3 includes an inner coil layer 7 and an outer coil layer 8, similar to the embodiments described above. However, in this modified example, the outer coil 12 is the first coil, positioned closer to the rotor 2, among the two types of coils, the inner coil 11 and the outer coil 12. The inner coil 11 is the second coil, positioned further away from the rotor 2.

[0047] Therefore, in this modified example, the electrical resistance of the coil windings is higher in each of the outer coils 12, which are the first coils located closer to the rotor 2, compared to each of the inner coils 11, which are the second coils located further away from the rotor 2. For example, each coil winding of the inner coils 11, which are the second coils, is made of copper, while each coil winding of the outer coils 12, which are the first coils, is made of aluminum, which has higher electrical resistance than copper.

[0048] In a configuration where the rotor 2 is located on the outer circumference relative to the stator 3, increasing the electrical resistance of each coil winding of the outer coil 12, which is the first coil located closer to the rotor 2, appropriately reduces the AC losses caused by the linkage of magnetic flux originating from the rotor 2 in the outer coil 12, where the influence of magnetic flux originating from the rotor 2 is greater. Therefore, in this modified example as well, the AC losses generated in the coils of the stator 3 are reduced. As a result, the torque that rotates the rotor 2 increases, and the torque characteristics of the electric motor 1 are improved.

[0049] Furthermore, in this modified configuration, the influence of magnetic flux originating from the rotor 2 is small in the inner coil 11, which is the second coil located on the side furthest from the rotor 2. Therefore, even if the electrical resistance of each coil winding of the inner coil 11 is reduced, the AC losses in the inner coil 11 are reduced. As a result of the reduced electrical resistance of the coil windings in each of the inner coils 11, the DC losses in the inner coils 11 are reduced, and the DC losses generated in the coils of the stator 3 are appropriately reduced. This further increases the torque that rotates the rotor 2, and further improves the torque characteristics of the electric motor 1.

[0050] Furthermore, in this modified example, it is preferable that the coil pitch α of each of the multiple inner coils 11 in the inner coil layer 7 and the multiple outer coils 12 in the outer coil layer 8 be greater than or equal to the angle αref obtained by dividing 360° by the total number of inner coils 11 and outer coils 12. This increases the area occupied by the inner coils 11 and outer coils 12 in the stator 3, and makes it possible to increase the amount of linked magnetic flux that links with the inner coils 11 and outer coils 12 in the generated rotating magnetic field.

[0051] Furthermore, in this modified configuration, it is preferable that the coil pitch α of each of the outer coils 12, which are the first coils located closer to the rotor 2, is larger than that of each of the inner coils 11, which are the second coils located further away from the rotor 2. In a configuration where the rotor 2 is located on the outer circumference relative to the stator 3, increasing the coil pitch α2 of each of the outer coils 12, which are the first coils located closer to the rotor 2, increases the amount of magnetic flux linkage with the coils (outer coils 12) at positions closer to the rotor 2 in the generated rotating magnetic field. As a result, the torque that rotates the rotor 2 is further increased, and the torque characteristics of the electric motor 1 are further improved.

[0052] Furthermore, in this modified configuration, it is preferable that each of the outer coils 12, which are the first coils located closer to the rotor 2, has a greater number of turns N than each of the inner coils 11, which are the second coils located further away from the rotor 2. In a configuration where the rotor 2 is located on the outer circumference relative to the stator 3, increasing the number of turns N2 of each of the outer coils 12, which are the first coils located closer to the rotor 2, makes it possible to appropriately increase the coil pitch α2 of each of the outer coils 12.

[0053] Furthermore, the stator structure of the stator 3 in the electric motor 1 of the above-described embodiment can also be applied as the stator structure of a generator. In a generator, a rotating magnetic field is generated by the rotation of the rotor. The rotating magnetic field generated by the rotation of the rotor induces a voltage (electromotive force) in the inner coil 11 and outer coil 12, which make up the coils of the stator.

[0054] In the generator's stator structure, the stator 3 comprises an inner coil layer 7 and an outer coil layer 8. The coil windings of the multiple inner coils 11 in the inner coil layer 7 are made from different materials than those of the multiple outer coils 12 in the outer coil layer 8. Furthermore, in each of the first coils, which are located closer to the rotor 2 among the inner coils 11 and outer coils 12, the electrical resistance of the coil windings is higher than that of each of the second coils, which are located further away from the rotor 2 among the inner coils 11 and outer coils 12. As a result, in the first coils, where the influence of magnetic flux from the rotor 2 is greater, the AC losses caused by the linkage of magnetic flux from the rotor 2 are appropriately reduced. Therefore, the AC losses generated in the coils of the stator 3 are reduced. In a generator, reducing AC losses in the stator coils increases the voltage induced in the inner coils 11 and outer coils 12.

[0055] Furthermore, in the stator structure of the generator, the influence of magnetic flux originating from the rotor 2 is small in the second coil, which is located on the side farther from the rotor 2. Therefore, even if the electrical resistance of each coil winding of the second coil is reduced, the AC loss in the second coil is reduced. As a result of the reduced electrical resistance of the coil winding in each of the second coils, the DC loss in the second coil is reduced, and the DC loss generated in the coils of the stator 3 is appropriately reduced. This further improves the voltage induced in the inner coil 11 and the outer coil 12 (coils of the stator 3).

[0056] Furthermore, in the stator structure of the generator, it is preferable that the coil pitch α of the inner coil 11 and the outer coil 12 be greater than or equal to the angle αref obtained by dividing 360° by the total number of inner coils 11 and outer coils 12. This increases the area occupied by the inner coils 11 and outer coils 12 in the stator 3, and makes it possible to increase the amount of linked magnetic flux that links with the inner coils 11 and outer coils 12 in the rotating magnetic field generated by the rotation of the rotor 2. In the generator, the amount of linked magnetic flux with the inner coils 11 and outer coils 12 increases, which appropriately increases the voltage induced in the inner coils 11 and outer coils 12 (coils of the stator 3).

[0057] Furthermore, in the stator structure of the generator, it is preferable that the coil pitch α is larger for each of the first coils, which are located closer to the rotor 2 among the inner coil 11 and the outer coil 12, compared to each of the second coils, which are located further away from the rotor 2 among the inner coil 11 and the outer coil 12. It is also preferable that the number of turns N is larger for each of the first coils compared to each of the second coils. In the stator structure of the generator, increasing the coil pitch of each of the first coils located closer to the rotor 2 increases the amount of flux linkage with the coils at positions close to the rotor 2 in the generated rotating magnetic field. As a result, the voltage induced in the coils of the stator 3 increases further.

[0058] According to at least one embodiment or example, in the inner coil layer, a plurality of coreless inner coils are arranged circumferentially, and in the outer coil layer, a plurality of coreless outer coils are arranged circumferentially on the outer periphery of the inner coil layer without contacting the inner coils. Furthermore, each coil winding of the inner coils is formed from a different material than each coil winding of the outer coils. This makes it possible to provide a stator structure in a rotating electric machine that can reduce AC losses in the stator coils.

[0059] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. The following are additional notes. [1] A stator structure in a rotating electric machine, An inner coil layer comprising multiple coreless inner coils, wherein the inner coils are arranged in a circumferential direction, An outer coil layer comprising a coreless plurality of outer coils, wherein the outer coils are arranged in the circumferential direction on the outer circumference side of the inner coil layer without contacting the inner coils, It is equipped with, The rotor is rotated by utilizing the rotating magnetic field generated by applying voltage to the inner coil and the outer coil, or by inducing a voltage in the inner coil and the outer coil by the rotating magnetic field generated by the rotation of the rotor. Each of the inner coil windings is formed from a different material than each of the outer coil windings. Stator structure. [2] The stator structure of [1] wherein the electrical resistance of the coil winding is higher in each of the first coils, which is located on the side closer to the rotor among the inner coils and the outer coils, compared to each of the second coils, which is located on the side further from the rotor among the inner coils and the outer coils. [3] Each of the coil windings of the first coil is formed from aluminum, Each of the coil windings of the second coil is formed from copper. [2] Stator structure. [Explanation of Symbols]

[0060] 1...Electric motor, 2...Rotor, 3...Stator, 7...Inner coil layer, 8...Outer coil layer, 11(11U,11V,11W)...Inner coil, 12(12U,12V,12W)...Outer coil, P...Rotation axis, B...Winding axis, α(α1,α2)...Coil pitch, αref...Angle, N(N1,N2)...Number of turns.

Claims

1. A stator structure in a rotating electric machine, An inner coil layer comprising multiple coreless inner coils, wherein the inner coils are arranged in a circumferential direction, An outer coil layer comprising a coreless plurality of outer coils, wherein the outer coils are arranged in the circumferential direction on the outer circumference side of the inner coil layer without contacting the inner coils, It is equipped with, The rotor is rotated by utilizing the rotating magnetic field generated by applying voltage to the inner coil and the outer coil, or by inducing a voltage in the inner coil and the outer coil by the rotating magnetic field generated by the rotation of the rotor. Each of the inner coil windings is formed from a different material than each of the outer coil windings. In each of the first coils, which is positioned closer to the rotor than the inner coil and the outer coil, the electrical resistance of the coil winding is higher than that of each of the second coils, which is positioned further away from the rotor than the inner coil and the outer coil. In each of the first coils, the coil pitch is larger than that of each of the second coils. Stator structure.

2. Each of the coil windings of the first coil is formed from aluminum. Each of the coil windings of the second coil is formed from copper. The stator structure according to claim 1.

Images