Rotating electric machines

Abstract

The present invention provides a rotating electrical machine capable of simply improving performance regardless of whether the number of slots per pole per phase is a fraction or an integer. The rotating electrical machine has a fractional slot structure in which the number of slots per pole per phase is expressed in its simplest fraction with a denominator of , or an integer slot structure in which the number of slots per pole per phase is a natural number. The rotating electrical machine comprises a hybrid phase belt group formed by sequentially stacking a first basic phase belt group, a second basic phase belt group, and a third basic phase belt group in radial slot directions. The first basic phase belt group comprises a plurality of basic phase belts arranged per pole, the second basic phase belt group comprises the first basic phase belt group offset by a predetermined number of slots in the direction of rotor rotation, and the third basic phase belt group comprises the second basic phase belt group offset by a predetermined number of slots in the direction of rotor rotation. The hybrid phase belt group has a balanced magnetizing force for each phase at each pole. When the number of radial layers of the first basic phase belt group is m1, the number of radial layers of the second basic phase belt group is m2, and the number of radial layers of the third basic phase belt group is m3, the relationship 0 < 2 × m2 / (m1 + m3) is satisfied.

Description

Technical Field

[0001] The present invention relates to a rotating electric machine including a stator having a plurality of slots for accommodating coils made of conductive wires, and a rotor facing the stator and having a plurality of magnetic poles. Background Art

[0002] Patent Document 1 discloses a rotating electric machine comprising an integer number of slots, the simplest fraction of the number of stator slots divided by the number of phases and the number of rotor poles (the number of slots per pole per phase) being a natural number. This rotating electric machine has multiple layers arranged radially inward within the slots, and in slot conductors of the same phase, the second and third layers are offset by one slot relative to the first layer, and the fourth layer is further offset by one slot relative to the second and third layers, thereby forming a slot conductor group (see [1]). Figure 12 The multiple slot conductors in the slot conductor group are housed in a predetermined number Ns of circumferentially adjacent slots. When the number of slots per pole per phase is NSPP and the number of layers is 2×NL, Ns = NSPP + NL. Thus, the invention described in Patent Document 1 aims to achieve reduced noise in a rotating electrical machine.

[0003] Patent Document 2 discloses a rotating electric machine comprising fractional slots, where the number of slots per pole and per phase is a fraction. Windings are arranged in three overlapping layers within each slot. The first layer of windings is arranged so that the windings of the three phases (U, V, and W) are arranged with rotational symmetry of ±120 degrees. The second layer of windings is arranged offset by L slots relative to the first layer. The third layer of windings is arranged offset by L slots relative to the first layer in a direction opposite to the offset direction of the second layer. Thus, the invention described in Patent Document 2 aims to reduce torque ripple in a three-phase AC motor.

[0004] Non-patent document 1 states that when it is necessary to remove slot high-order harmonic voltage, in the case of a fractional slot structure where the number of slots per pole per phase is a fraction, the diagonal slot spacing is 1 / c (c is the denominator of the simplest fraction of the number of slots per pole per phase).

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-150437

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2016-140202

[0007] Non-Patent Document 1: "Practical Electrical Equipment" by Masaru Moriyasu (Morihoku Publishing Co., Ltd., published on July 25, 2000 (first edition, first printing), p. 72)

[0008] However, the invention described in Patent Document 1 cannot be applied to rotating electrical machines with fractional-slot structures, where the number of slots per pole per phase is not a natural number. Specifically, in rotating electrical machines with fractional-slot structures, since the specified number Ns is not a natural number, it is impossible to specify the arrangement of multiple slot conductors. Furthermore, the definition of 2×NL assumes an even number of layers, making it inapplicable to rotating electrical machines with integer-slot structures, which have an odd number of layers.

[0009] Furthermore, the invention described in Patent Document 2 aims to reduce torque ripple, but its effectiveness in reducing noise and vibration in three-phase AC motors is limited. Specifically, while it can reduce noise and vibration caused by torque ripple, it cannot reduce noise and vibration caused by other factors. Specifically, in the three-phase AC motor described in Patent Document 2, the magnitude of the magnetizing force generated by windings containing the same phase and current in the same direction, housed in two circumferentially adjacent slots, varies circumferentially at a ratio of 4:3:3:4, repeating in this manner. Therefore, even if the three layers of windings are circumferentially offset by a predetermined slot size, the magnetizing force generated by energizing the windings becomes uneven for each pole. As a result, excitation forces in spatial deformation modes with a lower order than the number of magnetic poles of the rotor are more likely to be generated. Since the natural vibration frequencies of the stator in these low-order spatial deformation modes decrease, the resonant frequency of the stator in this rotating electrical machine decreases. A decrease in the resonant frequency increases the rotational speed range of the rotating electrical machine in which excitation forces with corresponding vibration frequencies are generated, expanding the rotational speed range in which noise and vibration become a problem. The operating range of rotating electric machines used to drive electric and hybrid vehicles covers the entire range of torque and rotational speed. Therefore, the use of such rotating electric machines increases the frequency of operating opportunities that cause increased noise and vibration.

[0010] Furthermore, as described in Non-Patent Document 1, in a rotating electric machine with a fractional slot structure, torque ripple (including cogging torque) can be reduced by skewing the slot pitch by 1 / c, but it is difficult to reduce the noise and vibration of the rotating electric machine. Specifically, in a rotating electric machine with a fractional slot structure, the equivalence of each pole in the distribution of electromagnetic attraction generated between the stator and rotor is destroyed, generating excitation forces of a spatial deformation mode of the order obtained by dividing the number of rotor poles by the aforementioned c. In other words, a rotating electric machine with a fractional slot structure is more likely to generate excitation forces of lower-order spatial deformation modes than a rotating electric machine with an integer slot structure (c = 1) with the same number of rotor poles. As a result, noise and vibration increase in the rotational speed range where the natural vibration frequency of the stator corresponding to the low-order spatial deformation mode coincides with the frequency of the excitation force of the low-order spatial deformation mode.

[0011] Therefore, a rotating electrical machine is desired that can easily improve performance regardless of whether the number of slots per pole per phase is a fractional number or an integer number. Summary of the Invention

[0012] The rotating electric machine according to the present invention is characterized in that it comprises: a stator having a plurality of slots for accommodating coils composed of conductive wires; and a rotor opposing the stator and having a plurality of magnetic poles, wherein the rotating electric machine has a fractional slot structure in which the number of slots per pole per phase, obtained by dividing the number of slots in the stator by the number of phases and the number of magnetic poles in the rotor, is expressed as a simplest fraction with a denominator of 2, or an integer slot structure in which the number of slots per pole per phase is a natural number, and a set of coil sides of the coils having the same phase and the same current direction and accommodated in one or a plurality of adjacent slots in each of the magnetic poles of the rotor is defined as a basic phase band, and a first basic phase band group, a second basic phase band group, and a third basic phase band group are sequentially stacked in radial directions of the slots. A hybrid phase belt group is formed, wherein the first basic phase belt group is formed by arranging the basic phase belts for each pole, the second basic phase belt group is formed by offsetting the first basic phase belt group by a predetermined number of slots in the direction of rotation of the rotor, and the third basic phase belt group is formed by offsetting the second basic phase belt group by the predetermined number of slots in the direction of rotation. For the hybrid phase belt group, the magnitude of the magnetizing force of each phase in each pole is balanced. When the number of radial layers of the first basic phase belt group is m1, the number of radial layers of the second basic phase belt group is m2, and the number of radial layers of the third basic phase belt group is m3, the relationship 0 < 2 × m2 / (m1 + m3) is satisfied. Here, the predetermined number of slots is the nearest integer to the number of slots per pole obtained by multiplying the number of slots per pole per phase by the number of phases in the fractional slot structure, and is 1 in the integer slot structure.

[0013] This structure balances the magnitude of the magnetizing forces of each phase within each rotor pole. Furthermore, due to the improved uniformity of the magnetizing force distribution, it is less likely to generate excitation forces from spatial deformation modes that are lower in order than the number of rotor poles. This reduces the noise and vibration caused by these low-order spatial deformation modes of the stator.

[0014] Furthermore, the inventors of the present invention (hereinafter referred to as "the present inventors") have repeatedly studied hybrid phase belt groups that can reduce noise and vibration caused by low-order spatial deformation modes of the stator. As a result, the present inventors discovered that, as in the present configuration, when the number of radial layers of the first basic phase belt group is m1, the number of radial layers of the second basic phase belt group is m2, and the number of radial layers of the third basic phase belt group is m3, and the relationship 0 < 2 × m2 / (m1 + m3) is satisfied, torque ripple can be reduced while maintaining nearly the desired torque, regardless of whether the slots are fractional or integer. Furthermore, noise and vibration can also be reduced in the fractional slots. In other words, adding m2 to m1 or m3 improves motor performance, thereby increasing the number of turns available in rotating electrical machines equipped with three basic phase belt groups. Thus, performance can be easily improved by simply specifying the number of radial layers, m1, m2, and m3, for both fractional and integer slots.

[0015] The other characteristic structure is that it satisfies the relationship 1≤2×m2 / (m1+m3)≤4.

[0016] If the relationship 1≤2×m2 / (m1+m3)≤4 is satisfied as in this structure, the noise, vibration, and torque ripple caused by the low-order spatial deformation modes of the stator can be further reduced.

[0017] Another characteristic structure is that the relationship m1=m3 is satisfied.

[0018] By satisfying the relationship m1=m3 as in this structure, the number of coil sides of the mixed same phase is arranged so that a concentrically wound coil structure is established. As a result, mechanical winding of the coil is possible, and the coil manufacturing method becomes extremely simple.

[0019] Another characteristic structure is that at least one of the above-mentioned stator and the above-mentioned rotor has: a reference part, which serves as a reference for the deflection; and a deflection part, which is arranged in a direction orthogonal to the above-mentioned rotation direction and the above-mentioned radial direction in a state of being offset in the above-mentioned rotation direction relative to the above-mentioned reference part, and the above-mentioned deflection part is set with a maximum value of the deflection amount of the above-mentioned deflection part relative to the above-mentioned reference part, so that the maximum value of the relative deflection amount of the above-mentioned stator and the above-mentioned rotor is converted into the size of one slot pitch of the stator core through continuous deflection.

[0020] In this structure, a maximum value for the skew of the skewed portion relative to the reference portion is set so that the maximum relative skew between the stator and rotor, when converted to a single slot pitch in the stator core, is equalized by continuous skew. As a result, the rotational electromagnetic attraction generated between the stator and rotor is evenly distributed across the entire orthogonal direction, thereby reducing noise and vibration caused by low-order spatial deformation modes. In particular, this skewed structure reduces noise and vibration in the low-speed range caused by the excitation forces of the stator's high-order rotational modes. The hybrid phase band structure and this skewed structure can both reduce noise and vibration at intermediate orders between high and low orders. In this way, whether using fractional or integer slots, the combined use of the hybrid phase band structure and this skewed structure can reduce noise and vibration at all rotational orders. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a partially enlarged cross-sectional view of a rotating electrical machine.

[0022] Figure 2 Schematic diagram showing a configuration example of a unit coil.

[0023] Figure 3 This is a conceptual diagram of concentric winding.

[0024] Figure 4 This is a schematic diagram showing an example of a phase arrangement of 8 poles and 60 slots.

[0025] Figure 5 This is a schematic diagram showing an example of a phase arrangement of 8 poles and 60 slots in this embodiment.

[0026] Figure 6 This is a schematic diagram showing an example of a phase arrangement of 8 poles and 60 slots in this embodiment.

[0027] Figure 7 Schematic diagram showing a phase arrangement of 8 poles and 60 slots in a comparative example.

[0028] Figure 8 This is a schematic diagram showing an example of a phase arrangement of 8 poles and 60 slots in this embodiment.

[0029] Figure 9 This is a schematic diagram showing an example of a phase arrangement of 8 poles and 72 slots in this embodiment.

[0030] Figure 10 This is a schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=1.5.

[0031] Figure 11 This is a schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=2.5.

[0032] Figure 12 This is a schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=3.5.

[0033] Figure 13 This is a schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=4.5.

[0034] Figure 14 Schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=1.

[0035] Figure 15 Schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=2.

[0036] Figure 16 Schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=3.

[0037] Figure 17 Schematic diagram showing an overview of the U-phase arrangement of a rotating electrical machine with Nspp=4.

[0038] Figure 18 This is a diagram showing simulation results of the amplitude ratio of the magnetic attraction force between the rotor and the stator in a rotating electrical machine with Nspp=2.5 (m1=m3).

[0039] Figure 19 It is a diagram showing simulation results of the torque and torque ripple of the rotating electrical machine when Nspp=2.5 (m1=m3).

[0040] Figure 20 Graphs showing simulation results of the magnetic attraction force amplitude ratio between the rotor and stator, torque, and torque ripple in a rotating electrical machine with Nspp=2.5 (m1=m3).

[0041] Figure 21 The diagram shows simulation results of the magnetic attraction force amplitude ratio between the rotor and the stator, torque, and torque ripple in a rotating electrical machine with Nspp=1.5, 2.5, and 3.5 (m1=m3).

[0042] Figure 22 This is a diagram showing simulation results of the amplitude ratio of the magnetic attraction force between the rotor and the stator in a rotating electrical machine with Nspp=2.5 (m1≠m3).

[0043] Figure 23 It is a diagram showing simulation results of the torque and torque ripple of the rotating electrical machine when Nspp=2.5 (m1≠m3).

[0044] Figure 24Graphs showing simulation results of the magnetic attraction force amplitude ratio between the rotor and stator, torque, and torque ripple in a rotating electrical machine with Nspp=2.5 (m1≠m3).

[0045] Figure 25 It is a diagram showing simulation results of the torque and torque ripple of the rotating electrical machine when Nspp=2 (m1=m3).

[0046] Figure 26 1 is a diagram showing simulation results of the torque and torque ripple of the rotating electrical machine when Nspp=2 (m1≠m3).

[0047] Figure 27 Graph showing the relationship between the ratio 2×m 2 / (m 1 +m 3 ) and the number of series-connected turns Nt in this embodiment.

[0048] Figure 28 It is a diagram showing the distribution of electromagnetic attractive force in a comparative example.

[0049] Figure 29 : is a figure which shows the distribution of electromagnetic attractive force in this embodiment.

[0050] Figure 30 This is a schematic diagram for explaining the continuous deflection in this embodiment.

[0051] Figure 31 This is a schematic diagram for explaining another V skew in the first embodiment.

[0052] Figure 32 This is a schematic diagram for explaining the step deviation in another second embodiment.

[0053] Description of Reference Numerals

[0054] 2…rotor; 3…stator; 5…basic phase belt; 11a…coil side; 31…stator core; 32…slot; 41…first reference portion (reference portion); 41a…first reference portion (reference portion) on one end side; 41b…first reference portion (reference portion) on the other end side; 42…continuously skewed portion (skewed portion); 42a…first continuously skewed portion (skewed portion); 42b…second continuously skewed portion (skewed portion); 43…second reference portion (reference portion); 44…step Ladder deflection part (deflection part); 45a…continuous deflection part (deflection part) on one end side; 45b…continuous deflection part (deflection part) on the other end side; 50…mixed phase belt group; 51…first basic phase belt group; 52…second basic phase belt group; 53…third basic phase belt group; M…motor (rotating motor); Nspp…number of slots per pole per phase; X…rotation direction; Y…radial direction; Z…axial direction (orthogonal direction); c…denominator of the simplest fraction; m1…number of layers; m2…number of layers; m3…number of layers. DETAILED DESCRIPTION

[0055] An embodiment of a rotating electrical machine according to the present invention is described below with reference to the accompanying drawings. In this embodiment, a three-phase AC synchronous motor (hereinafter referred to as motor M) is used as an example of a rotating electrical machine. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit and scope of the present invention.

[0056] [Basic structure]

[0057] like Figure 1 As shown, the motor M includes a stator 3 having a plurality of slots 32 for accommodating the coil sides 11a of a plurality of unit coils 11 (an example of a coil) formed of conductive wire (hereinafter referred to as "windings"); and a rotor 2, which faces the stator 3 and has a plurality of permanent magnets 22 (an example of a magnetic pole). In the following description, the rotational direction or counter-rotational direction of the rotor 2 is referred to as the circumferential direction X, the radial direction of the rotor 2 is referred to as the radial direction Y, and the direction parallel to the rotation axis of the rotor 2 is referred to as the axial direction Z (orthogonal direction). Furthermore, the direction of rotation of the rotor 2 in the circumferential direction X is referred to as the rotational direction X1, and the opposite direction is referred to as the counter-rotational direction X2. In the radial direction Y, the direction from the stator 3 toward the rotor 2 (toward the opening of the slots 32) is referred to as the radially inner direction Y1, and the direction from the rotor 2 toward the stator 3 is referred to as the radially outer direction Y2 (toward the bottom of the slots 32).

[0058] The stator 3 includes a cylindrical stator core 31 formed by laminating multiple magnetic steel plates. The stator core 31 comprises a yoke 31a formed annularly in the radially outward direction Y2, multiple teeth 31b protruding from the yoke 31a in the radially inward direction Y1, and flanges 31c arranged along the circumferential direction X at the protruding ends of the multiple teeth 31b. Slots 32 are formed between adjacent teeth 31b to accommodate the coil sides 11a of the unit coil 11 comprising the winding. The number of slots 32 provided is equal to the number of teeth 31b.

[0059] The rotor 2 includes a cylindrical rotor core 21 formed by laminating multiple magnetic steel plates, and multiple permanent magnets 22 embedded in the rotor core 21. The rotor core 21 is supported by a shaft member (not shown) and is configured such that the rotor 2 can rotate relative to the stator 3 in a rotation direction X1. The permanent magnets 22 are composed of rare earth magnets, for example, with north and south poles alternately arranged along the circumferential direction X. Alternatively, the outer circumferential surfaces of the multiple permanent magnets 22 may be exposed from the rotor core 21.

[0060] The motor M of this embodiment is configured such that the value obtained by dividing the number of slots 32 of the stator 3 by the number of phases (three phases in this embodiment) and the number of magnetic poles of the rotor 2 (hereinafter also referred to as the number of slots per pole per phase, or Nspp) is 1 or greater. When the number of slots per pole per phase is expressed as a simplest fraction, the denominator is 2, or the number of slots per pole per phase is an integer. Hereinafter, when the number of slots per pole per phase is expressed as a simplest mixed fraction, it is expressed as a+b / c (a is the integer part, b / c is the simplest fraction part, and b<c, where b and c are integers). In the case of integer slots, c=1. For example, in an 8-pole, 60-slot motor M, the number of slots per pole per phase is 5 / 2 (a=2, b=1, c=2), while in an 8-pole, 48-slot motor M, the number of slots per pole per phase is 2 (a=2, b=0, c=1).

[0061] The windings wound around the slots 32 are made of, for example, copper wire covered with an insulating layer. These windings use various types of wire, including round wire with a circular cross-section and polygonal wire. The windings around the slots 32 are typically wound in two layers, concentrically, or in wavy patterns.

[0062] exist Figure 2 In the figure, as an example of a winding method for the winding relative to the slot 32, a unit coil 11 that is double-wound or concentrically wound is shown. The unit coil 11 is usually composed of a winding that is wound multiple times, but for convenience, it is represented by a single line segment. The unit coil 11 has a pair of coil sides 11a, 11a along the axial direction Z and a pair of coil ends 11b, 11b along the circumferential direction X. The pair of coil sides 11a, 11a are the parts accommodated in the slot 32, and the pair of coil ends 11b, 11b are arranged on the two end surfaces of the tooth portion 31b in the axial direction Z and are electrically connected to the pair of coil sides 11a, 11a.

[0063] like Figure 1 As shown, the coils of each phase (U phase, V phase, W phase) are each formed by stacking a plurality of unit coils 11 in the slot 32 along the radial direction Y. In the case of fractional slots, there are a plurality of double-layer units (for example, Figure 4 In the case of an integer number of slots, there are four groups of 1st to 2nd layers, 3rd to 4th layers, 5th to 6th layers, and 7th to 8th layers. In the case of an integer number of slots, there are multiple layers of unit coils 11 stacked on the coil side 11a of one unit coil 11 (for example, Figure 9 The coils for each phase in this embodiment are stacked in multiple layers along the radial direction Y and housed in slots 32. Furthermore, the three-phase coils are electrically connected via a Y-junction. Alternatively, the three-phase coils may be electrically connected via a Δ-junction, without particular limitation.

[0064] In the case of double-layer winding in fractional slots, the coil pitch is the integer closest to the number of slots per pole obtained by dividing the number of slots 32 of the stator 3 by the number of magnetic poles of the rotor 2. For example, in the case of an 8-pole 60-slot motor M (the number of slots per pole is 7.5), this coil pitch is 7 slots (short-pitch winding) or 8 slots (long-pitch winding).

[0065] exist Figure 3 In the figure, concentric winding is shown as an example of a winding method for the windings in the slots 32. Multiple pole pair coils 10, each facing the magnetic poles of the rotor 2, include a first pole coil 10A and a second pole coil 10B. The first pole coil 10A and the second pole coil 10B are electrically connected in series. The white circle in the figure indicates the winding start point, and the black circle indicates the winding end point.

[0066] In this embodiment, the first pole coil 10A includes a plurality of (two) first unit coils 11A and second unit coils 11B having different coil spacings between a pair of coil sides 11a, 11a. For example, in the case of 8 poles and 60 slots (Nspp = 2.5, m1 = 1, m2 = 2, m3 = 1), the coil spacing between a pair of coil sides 11a, 11a of the first unit coil 11A is set to 7 slots, and the coil spacing between a pair of coil sides 11a, 11a of the second unit coil 11B is set to 5 slots (see also). Figures 5 and 6 Here, m1 is the number of double-layer units in the radial direction Y (one group), with 1 to 2 layers as a group; m2 is the number of double-layer units in the radial direction Y (two groups), with 3 to 4 layers as a group and 5 to 6 layers as a group; and m3 is the number of double-layer units in the radial direction Y (one group), with 7 to 8 layers as a group. The first unit coil 11A and the second unit coil 11B are concentrically wound and electrically connected in series via the inter-unit coil connection 82 to form the first pole coil 10A.

[0067] The second pole coil 10B includes a plurality of (two) third unit coils 11C and a fourth unit coil 11D, each having a different coil pitch between a pair of coil sides 11a, 11a. For example, in the case of 8 poles and 60 slots (Nspp = 2.5), the coil pitch between a pair of coil sides 11a, 11a of the third unit coil 11C is set to 6 slots, and the coil pitch between a pair of coil sides 11a, 11a of the fourth unit coil 11D is set to 4 slots (see also Figures 5 and 6 The third unit coil 11C and the fourth unit coil 11D are concentrically wound and electrically connected in series via the inter-unit coil connection portion 82 to form the second pole coil 10B.

[0068] The first pole coil 10A and the second pole coil 10B are positioned opposite adjacent pairs of magnetic poles (two poles) among the plurality of magnetic poles (eight poles in the case of eight poles and sixty slots). Furthermore, the first pole coil 10A and the second pole coil 10B are electrically connected in series via an inter-pole coil connection 83. The coil pitch between each pair of coil sides 11a, 11a of the first unit coil 11A, the second unit coil 11B, the third unit coil 11C, and the fourth unit coil 11D is different, and is set to be less than the seven slots (short-pitch winding) of the double-layer winding coil pitch. Therefore, compared to double-layer winding, concentric winding can shorten the conductor length and reduce the amount of conductor used in the stator 3.

[0069] (Noise and Vibration of Motor M Caused by Phase Arrangement of Stator 3)

[0070] exist Figures 5 and 6 and Figures 8 and 9 , illustrates an example of the phase arrangement of the windings wound around the multiple slots 32 according to this embodiment and the magnetic pole-to-pole orientation of a pair of rotor 2 magnetic poles (N and S poles). The yoke 31a, teeth 31b, and windings are omitted in this figure. The consecutive numbers in the upper layers of the figure represent the slot numbers of each slot 32. The phases of the U-phase coil, the V-phase coil, and the W-phase coil are sequentially shifted by 120° electrical angle. The following description uses the U-phase coil as a representative example, as each phase (U, V, and W) has the same phase arrangement except for the phase shift. In the figures, "U" and "U" designations indicate opposite current directions. The same designation ("U" or "U") indicates coil sides 11a with the same current direction. In the radial direction Y, the coil sides 11a located most radially outward in the direction Y2 are sequentially represented as the first layer, the second layer, and so on, as they move from the coil side 11a located radially inward in the direction Y1 to the coil side 11a located radially outward in the direction Y2.

[0071] The set of coil sides 11 a, which are in phase and have the same current direction, housed in one or multiple adjacent slots 32 for each magnetic pole of the rotor 2, is defined as a basic phase band 5. Here, "the set of coil sides 11 a, which are in phase and have the same current direction, housed in one or multiple adjacent slots 32 for each pole" is synonymous with the set of coil sides 11 a, which are in phase and have the same current direction, housed in one slot 32 or in multiple slots 32 continuously adjacent in the circumferential direction X.

[0072] In the fractional slot structure of 8 poles and 60 slots (Nspp = 5 / 2, a = 2, b = 1, c = 2), as Figures 4 to 8As shown, the fundamental phase band 5 is composed of a first-pole fundamental phase band 5A and a second-pole fundamental phase band 5B, each of which is opposed to a pair of adjacent magnetic poles (two poles) among a plurality of magnetic poles (eight poles in the case of eight poles and sixty slots). The first-pole fundamental phase band 5A and the second-pole fundamental phase band 5B are arranged in different phases, forming fundamental phase bands 5 with a phase difference from each other.

[0073] As a comparative example, in a fractional slot structure with 8 poles and 60 slots (Nspp = 5 / 2, a = 2, b = 1, c = 2), Figure 7 In the case of the basic motor M shown as consisting only of the first layer and the second layer, the multiple (5) coil sides 11a of the basic phase belt 5 arranged in the first slot to the third slot are 1 in the first slot, 2 in the second slot, and 2 in the third slot. The center C11 of the multiple coil sides 11a of the basic phase belt 5 is 2.2 as shown in the following formula (1).

[0074] Formula (1) C11 = (1 × 1 + 2 × 2 + 3 × 2) / (1 + 2 + 2) = 2.2

[0075] Similarly, the center C12 of the multiple (5) coil sides 11a of the basic phase band 5 arranged in the ninth to eleventh slots is 9.8 as shown in the following formula (2), and the center C13 of the multiple (5) coil sides 11a of the basic phase band 5 arranged in the sixteenth to eighteenth slots is 17.2 as shown in the following formula (3).

[0076] Formula (2) C12 = (9 × 2 + 10 × 2 + 11 × 1) / (2 + 2 + 1) = 9.8

[0077] Formula (3) C13 = (16 × 1 + 17 × 2 + 18 × 2) / (1 + 2 + 2) = 17.2

[0078] According to the calculation results above, the distances between the centers of the coil sides 11a of the U-phase fundamental phase band 5 in the comparative example are C12 - C11 = 7.6 and C13 - C12 = 7.4, with 7.6 and 7.4 alternating. In other words, the distances between the centers of the coil sides 11a of the adjacent fundamental phase bands 5 of the same phase in the circumferential direction X are not uniform for each pole. Consequently, the attractive force distributions between adjacent magnetic poles in the circumferential direction X differ, and the attractive force distributions acting on the multiple teeth 31b are not equivalent for each magnetic pole, but are equivalent across every other pole within each magnetic pole pair (every two magnetic poles). These two attractive force distributions exert a component of the excitation force on the stator 3 of a lower order (in this embodiment, the fourth order in the spatial deformation mode) than the order determined by the number of magnetic poles of the rotor 2 (in this embodiment, eight poles) (in this embodiment, the eighth order in the spatial deformation mode). As a result, it is easy to generate excitation forces of spatial deformation modes that are lower than the number of magnetic poles of the rotor 2. In the speed range where the natural vibration number of the stator 3 corresponding to the low-order spatial deformation mode is consistent with the frequency of the excitation forces of the low-order spatial deformation mode, the noise and vibration become larger.

[0079] In the comparative example, the number of coil sides 11a constituting the U-phase basic phase band 5 is balanced per pole (five), so the magnitude of the magnetizing force generated when energizing the stator 3 windings is balanced per pole. However, as mentioned above, the 1 / 2 series (c=2) motor M has two magnetizing force distributions. Therefore, in this embodiment, while the magnetizing force magnitudes are balanced, the imbalanced magnetizing force distribution (a lack of rotational symmetry) is corrected, thereby reducing the noise and vibration of the motor M caused by the phase arrangement of the stator 3 windings.

[0080] Therefore, if Figures 5 and 6 and Figures 8 and 9As shown, in this embodiment, a hybrid phase belt group 50 is formed by stacking a first basic phase belt group 51, a second basic phase belt group 52, and a third basic phase belt group 53 in this order from the radially outward direction Y2 to the radially inward direction Y1 of the slots 32. The first basic phase belt group 51 is a collection of a plurality of basic phase belts 5 arranged for each pole. The second basic phase belt group 52 is formed by offsetting the first basic phase belt group 51 by a predetermined number of slots in the rotational direction X1 of the rotor 2. The third basic phase belt group 53 is formed by offsetting the second basic phase belt group 52 by a predetermined number of slots in the rotational direction X1. The predetermined number of slots is the nearest integer (3×Nspp±1 / c) to the value obtained by multiplying the number of slots per pole per phase by 3 (multiplied by the number of phases) for fractional slots, and is a single slot, which is ±1 / c (c=1 or -1) for integer slots. Hereinafter, the mixed phase belt in the mixed phase belt group 50, in which the basic phase belt 5 is mixed at each pole, is referred to as the mixed phase belt 50A. Furthermore, the number of coil sides 11a constituting the mixed phase belt 50A, when electrically connected in series, is referred to as the number of series-connected turns = Nt (= M × (a × c + b), M = m1 + m2 + m3). Here, m1 is the number of layers in the radial direction Y of the first basic phase belt group 51, m2 is the number of layers in the radial direction Y of the second basic phase belt group 52, and m3 is the number of layers in the radial direction Y of the third basic phase belt group 53.

[0081] exist Figures 5 to 8 In FIG, a motor M with a fractional slot structure of 8 poles and 60 slots (Nspp=5 / 2, a=2, b=1, c=2) is shown. Figure 9 In the figure, an integer slot structure motor M with 8 poles and 72 slots (Nspp=3, a=3, b=0, c=1) is shown. In the fractional slot structure motor M with 8 poles and 60 slots, the prescribed number of slots is 3×Nspp±1 / c=7 or 8. Figure 5 In one example of the present embodiment shown in FIG. 1 (hereinafter also referred to as “the present embodiment”), the number of slots is set to 7. Figure 6 In the embodiment shown in FIG, the number of slots is set to 8. In addition, in the fractional slots, Figure 4 As shown, when the first basic phase belt group 51 is shifted by a predetermined number of slots (7 slots) in the rotation direction X1 to form the second basic phase belt group 52, the current direction in each pole becomes opposite, so as shown in FIG. Figure 5 As shown, the current direction in the second basic phase band group 52 is reversed ( Figure 6 In the motor M with an integer slot structure of 8 poles and 72 slots, the number of slots is set to ±1. Figure 9 In the present embodiment shown, the predetermined number of slots is set to 1 slot.

[0082] exist Figure 5In the embodiment shown, the plurality of coil sides 11a (Nt=20) of the mixed phase band 50A arranged in the zeroth slot to the third slot are 1 in the zeroth slot, 7 in the first slot, 8 in the second slot, and 4 in the third slot. The center C11 of the plurality of coil sides 11a of the mixed phase band 50A is 1.75 as shown in the following formula (4).

[0083] Formula (4) C11 = (0 × 1 + 1 × 7 + 2 × 8 + 3 × 4) / (1 + 7 + 8 + 4) = 1.75

[0084] Similarly, the center C12 of the multiple (Nt=20) coil sides 11a of the mixed phase belt 50A arranged in the eighth to eleventh slots is 9.25 as shown in the following formula (5), and the center C13 of the multiple (Nt=20) coil sides 11a of the mixed phase belt 50A arranged in the fifteenth to eighteenth slots is 16.75 as shown in the following formula (6).

[0085] Formula (5) C12 = (8 × 4 + 9 × 8 + 10 × 7 + 11 × 1) / (4 + 8 + 7 + 1) = 9.25

[0086] Formula (6) C13 = (15 × 1 + 16 × 7 + 17 × 8 + 18 × 4) / (1 + 7 + 8 + 4) = 16.75

[0087] exist Figure 6 In the embodiment shown, the plurality of coil sides 11a (Nt = 20) of the mixed phase band 50A arranged in the first to fourth slots are 1 in the first slot, 7 in the second slot, 8 in the third slot, and 4 in the fourth slot. The center C11 of the plurality of coil sides 11a of the mixed phase band 50A is 2.75 as shown in the following formula (7).

[0088] Formula (7) C11 = (1 × 1 + 2 × 7 + 3 × 8 + 4 × 4) / (1 + 7 + 8 + 4) = 2.75

[0089] Similarly, the center C12 of the multiple (Nt=20) coil sides 11a of the mixed phase belt 50A arranged in the ninth to twelfth slots is 10.25 as shown in the following formula (8), and the center C13 of the multiple (Nt=20) coil sides 11a of the mixed phase belt 50A arranged in the sixteenth to nineteenth slots is 17.75 as shown in the following formula (9).

[0090] Formula (8) C12 = (9 × 4 + 10 × 8 + 11 × 7 + 12 × 1) / (4 + 8 + 7 + 1) = 10.25

[0091] Formula (9) C13 = (16 × 1 + 17 × 7 + 18 × 8 + 19 × 4) / (1 + 7 + 8 + 4) = 17.75

[0092] The number of coil sides 11a constituting the U-phase mixed phase belt group 50 is Nt=20, which is balanced in each pole. Therefore, the magnitude of the magnetic force generated when the stator 3 winding is energized is balanced in each pole. Figures 5 and 6 In the example shown, C12 - C11 = 7.5, and C13 - C12 = 7.5, achieving a uniform distance between the centers of the coil sides 11a of the adjacent mixed-phase belts 50A of the same phase (U phase) in the circumferential direction X. This makes the magnetizing force distribution more equivalent at each pole, and the motor M of this embodiment can be considered to have a state closer to a uniform magnetizing force distribution.

[0093] As described above, in this embodiment, the rotational symmetry of the magnetic force distribution is improved. As a result, the motor M of this embodiment reduces the excitation force of orders lower than the order (spatial deformation mode order 4) determined by the number of magnetic poles (8 poles) of the rotor 2 (spatial deformation mode order 8). This increases the rotational speed consistent with the natural vibration frequency of the stator core 31, allowing it to be set, for example, outside the operating speed range. In other words, the motor M of this embodiment can avoid the chance of resonance of the rotor 2 within the operating speed range, thereby reducing the noise and vibration of the motor M.

[0094] When the number of layers in the radial direction Y of the first basic phase belt group 51 is set to m1, the number of layers in the radial direction Y of the second basic phase belt group 52 is set to m2, and the number of layers in the radial direction Y of the third basic phase belt group 53 is set to m3, Figures 5 and 6 In the embodiment shown in FIG, m1=2, m2=4, m3=2, and m1=m3 is assumed. On the other hand, in the case of Figure 8 As in the embodiment shown in FIG. 1 , m1=4, m2=4, m3=2, and m1≠m3, the same as Figure 7 Compared with the comparative example shown, the magnetizing force distribution can also be made more balanced.

[0095] For example, Figure 8 As shown in the figure, in an 8-pole 60-slot motor M (Nspp = 5 / 2, a = 2, b = 1, c = 2), when m1 = 4, m2 = 4, m3 = 2, and Nt = 25, C11 = 1.84, C12 = 9.36, and C13 = 16.84. As a result, C12-C11 = 7.52, C13-C12 = 7.48, which is the same as Figure 7 Compared with the comparative example (C12-C11=7.6, C13-C12=7.4) shown in the figure, the magnetic force distribution is Figure 8In this embodiment, the motor M, which has a fractional slot structure with c=2, has three basic phase belt groups 51, 52, and 53 that are offset by a predetermined number of slots. This improves the rotational symmetry of the magnetic force distribution and reduces the noise and vibration of the motor M caused by the low-order (fourth-order spatial deformation mode) excitation force.

[0096] like Figure 9 As shown in this embodiment, for a motor M with an integer-slot structure, the first layer of basic phase belts 5 has three basic phase belts per pole, resulting in a balanced magnetizing force and magnetizing force distribution. However, even when three basic phase belt groups 51, 52, and 53 are provided, each offset by a predetermined number of slots, as in this embodiment, the magnetizing force and magnetizing force distribution are also balanced. As described above, the motor M of this embodiment comprises a hybrid phase belt group 50 formed by stacking a first basic phase belt group 51, a second basic phase belt group 52, and a third basic phase belt group 53 in this order from the radially outward direction Y2 to the radially inward direction Y1 of the slots 32. The first basic phase belt group 51 is a collection of multiple basic phase belts 5 arranged for each pole, the second basic phase belt group 52 is formed by offsetting the first basic phase belt group 51 by a predetermined number of slots (one slot) in the rotational direction X1 of the rotor 2, and the third basic phase belt group 53 is formed by offsetting the second basic phase belt group 52 by a predetermined number of slots (one slot) in the rotational direction X1 of the rotor 2.

[0097] In 8-pole 72-slot Figure 9 In the present embodiment shown, the plurality of (Nt=12) coil sides 11a of the mixed phase band 50A arranged in the zeroth slot to the fourth slot are one in the zeroth slot, three in the first slot, four in the second slot, three in the third slot, and one in the fourth slot, and the center C11 of the plurality of coil sides 11a of the mixed phase band 50A is 2 as shown in the following formula (10).

[0098] Formula (10) C11 = (0 × 1 + 1 × 3 + 2 × 4 + 3 × 3 + 4 × 1) / (1 + 3 + 4 + 3 + 1) = 2

[0099] Similarly, the center C12 of the multiple (Nt=12) coil sides 11a of the mixed phase belt 50A arranged in the ninth to thirteenth slots is 11 as shown in the following formula (11), and the center C13 of the multiple (Nt=12) coil sides 11a of the mixed phase belt 50A arranged in the eighteenth to twenty-second slots is 21 as shown in the following formula (12).

[0100] Formula (11) C12 = (9 × 1 + 10 × 3 + 11 × 4 + 12 × 3 + 13 × 1) / (1 + 3 + 4 + 3 + 1) = 11

[0101] Formula (12) C13 = (18 × 1 + 19 × 3 + 20 × 4 + 21 × 3 + 22 × 1) / (1 + 3 + 4 + 3 + 1) = 20

[0102] Thus, even in the motor M with an integer slot structure, the number of coil sides 11a constituting the mixed phase belt group 50 of the U phase is Nt=12, which is balanced for each pole. Therefore, the magnitude of the magnetic force generated when the stator 3 winding is energized is balanced for each pole. Figure 9 In the example shown, C12 - C11 = 9 and C13 - C12 = 9. The distance between the centers of the coil sides 11a of the adjacent mixed-phase belts 50A of the same phase (U phase) in the circumferential direction X is uniform for each pole and corresponds to the number of slots per pole, i.e., the field pole pitch of 72 / 8 = 9. This results in an equivalent magnetizing force distribution for each pole, and the motor M of this embodiment can be considered to have a single magnetizing force distribution.

[0103] When the number of layers in the radial direction Y of the first basic phase belt group 51 is set to m1, the number of layers in the radial direction Y of the second basic phase belt group 52 is set to m2, and the number of layers in the radial direction Y of the third basic phase belt group 53 is set to m3, Figure 9 In the embodiment shown, m1 = 1, m2 = 2, and m3 = 1, assuming m1 = m3. On the other hand, although not shown, in a motor M with an integer slot structure, the magnetic force distribution is also balanced when m1 = 2, m2 = 2, and m3 = 1, as in the case where m1 ≠ m3.

[0104] For example, in an 8-pole, 72-slot motor M, if m1 = 2, m2 = 2, and m3 = 1, C11 = 1.8, C12 = 10.8, and C13 = 19.8. Consequently, C12 - C11 = 9 and C13 - C12 = 9, making the magnetizing force distribution equivalent for each pole. The motor M of this embodiment can be considered to have a single magnetizing force distribution. Thus, the motor M of this embodiment, with its integer-slot structure, maintains rotational symmetry in the magnetizing force distribution even when it includes three basic phase belt groups 51, 52, and 53, each offset by a predetermined number of slots. This reduces noise and vibration in the motor M.

[0105] exist Figures 10 to 17 In the embodiment shown, the change of m2 when m1=m3 is shown. Figure 10 8 poles and 36 slots (Nspp=3 / 2, a=1, b=1, c=2) are shown in Figure 11 8 poles and 60 slots (Nspp = 5 / 2, a = 2, b = 1, c = 2) are shown in Figure 12 8 poles and 84 slots (Nspp = 7 / 2, a = 3, b = 1, c = 2) are shown in FIG. Figure 13The motor M with a fractional slot structure of 8 poles and 108 slots (Nspp=9 / 2, a=4, b=1, c=2) is shown in FIG. Figure 14 In the figure, 8 poles and 24 slots (Nspp=1, a=1, b=0, c=1) are shown. Figure 15 8 poles and 48 slots (Nspp=2, a=1, b=0, c=1) are shown in FIG. Figure 16 8 poles and 72 slots (Nspp=3, a=1, b=0, c=1) are shown in FIG. Figure 17 ] shows an 8-pole, 96-slot (Nspp = 4, a = 1, b = 0, c = 1) integer-slot motor M. While all m1 and m3 are set to 1, the same effects can be achieved by multiplying m1, m2, and m3, so detailed description is omitted.

[0106] First, the motor M with a fractional slot structure of c = 2 will be described. In the motor M with an 8-pole 36-slot fractional slot structure, the prescribed number of slots is 3×Nspp±1 / c=4 or 5. Figure 10 In the embodiment shown, the prescribed number of slots is set to 4 slots. Figure 10 The order from the upper layer to the lower layer is (m1, m2, m3, Nt) = (2, 2, 2, 9), (2, 4, 2, 12), (2, 6, 2, 15), (2, 8, 2, 18). At this time, the centers C11, C12, and C13 of the plurality of coil sides 11a of the mixed phase band 50A arranged in the 0th to 2nd slots, the 5th to 7th slots, and the 9th to 11th slots are from Figure 10 The distance between the centers of the coil sides 11a of the adjacent mixed phase belts 50A of the same phase (U phase) in the circumferential direction X is (C11, C12, C13) = (11 / 9, 52 / 9, 92 / 9), (15 / 12, 69 / 12, 123 / 12), (19 / 15, 86 / 15, 154 / 15), (23 / 18, 103 / 18, 185 / 18). Figure 10 From the upper layer to the lower layer, the order becomes (C12-C11, C13-C12) = (41 / 9, 40 / 9), (54 / 12, 54 / 12), (67 / 15, 68 / 15), and (80 / 18, 82 / 18). This improves the rotational symmetry of the magnetic force distribution compared to a basic motor M consisting only of the first and second layers (centers (5 / 3, 19 / 3, 32 / 3), center-to-center distances (14 / 3, 13 / 3), thereby reducing noise and vibration in the motor M.

[0107] In the motor M with 8 poles and 60 slots and fractional slot structure, the prescribed number of slots is 3×Nspp±1 / c=7 or 8. Figure 11 In the embodiment shown, the prescribed number of slots is set to 7 slots. Figure 11 The order from the upper layer to the lower layer is (m1, m2, m3, Nt) = (2, 2, 2, 15), (2, 4, 2, 20), (2, 6, 2, 25), (2, 8, 2, 30). At this time, the centers C11, C12, and C13 of the plurality of coil sides 11a of the mixed phase band 50A arranged in the 0th to 3rd slots, the 8th to 11th slots, and the 15th to 18th slots are from Figure 11 The distance between the centers of the coil sides 11a of the adjacent mixed phase belts 50A of the same phase (U phase) in the circumferential direction X is (C11, C12, C13) = (26 / 15, 139 / 15, 251 / 15), (35 / 20, 185 / 20, 335 / 20), (44 / 25, 231 / 25, 419 / 25), (53 / 30, 277 / 30, 503 / 30). Figure 11 From the upper layer to the lower layer, the order becomes (C12-C11, C13-C12) = (113 / 15, 112 / 15), (150 / 20, 150 / 20), (187 / 25, 188 / 25), (224 / 30, 226 / 30). This improves the rotational symmetry of the magnetic force distribution compared to a basic motor M consisting only of the first and second layers (centers (11 / 5, 49 / 5, 86 / 5), center-to-center distances (38 / 5, 37 / 5), thereby reducing noise and vibration in the motor M.

[0108] In the motor M with 8 poles and 84 slots, the number of slots is 3×Nspp±1 / c=10 or 11. Figure 12 In the embodiment shown, the prescribed number of slots is set to 10 slots. Figure 12 The order from the upper layer to the lower layer is (m1, m2, m3, Nt) = (2, 2, 2, 21), (2, 4, 2, 28), (2, 6, 2, 35), (2, 8, 2, 42). At this time, the centers C11, C12, and C13 of the plurality of coil sides 11a of the mixed phase band 50A arranged in the 0th to 4th slots, the 11th to 15th slots, and the 21st to 25th slots are from Figure 12 From the upper layer to the lower layer, the order is (C11, C12, C13) = (47 / 21, 268 / 21, 488 / 21), (63 / 28, 357 / 28, 651 / 28), (79 / 35, 446 / 35, 814 / 35), (95 / 42, 535 / 42, 977 / 42). The distance between the centers of the coil sides 11a of the adjacent mixed phase belt 50A of the same phase (U phase) in the circumferential direction X is from Figure 12From the upper layer to the lower layer, the order becomes (C12-C11, C13-C12) = (221 / 21, 220 / 21), (294 / 28, 294 / 28), (367 / 35, 368 / 35), (440 / 42, 442 / 42). This improves the rotational symmetry of the magnetic force distribution compared to a basic motor M consisting only of the first and second layers (centers (19 / 7, 93 / 7, 166 / 7), center-to-center distances (74 / 7, 73 / 7), thereby reducing noise and vibration in the motor M.

[0109] In the motor M with 8 poles and 108 slots and a fractional slot structure, the number of slots is 3×Nspp±1 / c=13 or 14. Figure 13 In the embodiment shown, the number of slots is set to 13. Figure 12 The order from the upper layer to the lower layer is (m1, m2, m3, Nt) = (2, 2, 2, 27), (2, 4, 2, 36), (2, 6, 2, 45), (2, 8, 2, 54). At this time, the centers C11, C12, and C13 of the plurality of coil sides 11a of the mixed phase band 50A arranged in the 0th to 5th slots, the 15th to 20th slots, and the 29th to 34th slots are from Figure 13 The distance between the centers of the coil sides 11a of the adjacent mixed phase belts 50A of the same phase (U phase) in the circumferential direction X is (C11, C12, C13) = (74 / 27, 439 / 27, 803 / 27), (99 / 36, 585 / 36, 1071 / 36), (124 / 45, 731 / 45, 1339 / 45), (149 / 54, 877 / 54, 1607 / 54). Figure 13 From the upper layer to the lower layer, the order becomes (C12-C11, C13-C12) = (365 / 27, 364 / 27), (486 / 36, 486 / 36), (607 / 45, 608 / 45), (728 / 54, 730 / 54). This improves the rotational symmetry of the magnetic force distribution compared to a basic motor M consisting only of the first and second layers (centers (29 / 9, 151 / 9, 272 / 9), center-to-center distances (122 / 9, 121 / 9), thereby reducing noise and vibration in the motor M.

[0110] Like this, in the motor M with a fractional slot structure of c=2, the first pole basic phase band 5A and the second pole basic phase band 5B respectively facing a pair of adjacent magnetic poles (2 poles) among a plurality of magnetic poles (8 poles in the case of 8 poles and 60 slots) become basic phase bands 5 having a phase difference with each other, and the magnetizing force and the magnetizing force distribution become more balanced by having three basic phase band groups 51, 52, and 53 that are respectively offset by a specified number of slots.

[0111] Next, the motor M with an integer slot structure will be described. In the motor M with an integer slot structure, since the coil sides 11a of the adjacent mixed phase belts 50A all have the same structure, the distance between the centers of the coil sides 11a of the adjacent mixed phase belts 50A of the same phase (U phase) is calculated as follows: Figures 14 to 17 The order is 3 slots, 6 slots, 9 slots, and 12 slots. Thus, by providing three basic phase belt groups 51, 52, and 53 that are offset by a predetermined number of slots, the phase belt distribution is smoothed while maintaining the rotational symmetry of the magnetic force distribution. This reduces the torque ripple of the motor M and reduces the noise and vibration caused by it.

[0112] (Phase configuration of stator 3 suitable for concentric winding)

[0113] If the number of layers m1 in the radial direction Y of the first basic phase band group 51 and the number of layers m3 in the radial direction Y of the third basic phase band group 53 are the same (m1=m3), then Figure 3 The concentric winding structure shown is a continuous winding structure of the first unit coil 11A and the second unit coil 11B of the first pole coil 10A, and the third unit coil 11C and the fourth unit coil 11D of the second pole coil 10B. Figure 5 In the illustrated embodiment, the number of coil sides 11a of the mixed-phase strip 50A in the second and ninth slots is eight, allowing for a single coil formed by continuously winding a collection of unit coils 11, which serve as concentrically wound outer coils. Similarly, the number of coil sides 11a of the mixed-phase strip 50A in the third and eighth slots is four, allowing for a single coil formed by continuously winding a collection of unit coils 11, which serve as concentrically wound inner coils. By inserting the coil sides 11a of the U-phase mixed-phase strip 50A in the second and ninth slots, and the third and eighth slots, as a single coil into the slot 32, followed by the V-phase and W-phase single coils, the wiring of the windings inserted into each slot 32 is simplified and miniaturized, thereby improving the workability of the winding installation operation.

[0114] On the other hand, Figure 8 As shown in this embodiment, in an 8-pole, 60-slot motor M (Nspp = 5 / 2, a = 2, b = 1, c = 2), if m1 = 4, m2 = 4, m3 = 2, and Nt = 25 (m1 ≠ m3), it is impossible to wind the assembly of concentrically wound unit coils 11 continuously, as indicated by the two-dot chain line. For example, it is necessary to provide an assembly of concentrically wound unit coils 11 corresponding to the first and second layers in the third and ninth slots, and another assembly of concentrically wound unit coils 11 corresponding to the third to tenth layers in the third and eighth slots. Therefore, two types of unit coil 11 assemblies are required in the third slot.

[0115] In other words, if m1=m3, then Figures 10 to 17 As shown, the coil side 11a of the mixed phase tape 50A can be treated as an integral coil consisting of an inner coil and an outer coil wound concentrically.

[0116] The structure in which the proportion of each phase (for example, U phase) in each slot 32 is arranged in the concentric winding is used as Figures 10 to 17 The concentric winding structure is shown. The inventors discovered that the calculation can be performed using the turns ratio n = M / m1 (here, M = m1 + m2 + m3) of the unit coils 11 constituting the concentric winding. Furthermore, in the illustrated concentric winding structure, the winding structure of the pole pair coil 10 is shown as the first pole coil 10A & the second pole coil 10B. The portions connected by "-" represent the innermost coils in each pole coil 10A, 10B, starting from the outermost coil.

[0117] First, the motor M with a fractional slot structure is described. Figure 10 In the case of the motor M with Nspp = 1.5 shown, the equation is 1 / 2 & ((2n-1) / 2n) - (1 / 2n). For example, if m1 = 2, m2 = 2, and m3 = 2, n = 3, which can be expressed as 1 / 2 & 5 / 6 - 1 / 6. That is, the U-phase first pole coil 10A wound between the second and fifth slots occupies three of the six layers, the outer coil of the U-phase second pole coil 10B wound between the sixth and tenth slots occupies five of the six layers, and the inner coil of the U-phase second pole coil 10B wound between the seventh and ninth slots occupies one of the six layers.

[0118] exist Figure 11 In the case of the motor M with Nspp=2.5, Figure 10 Compared to the simplest mixed number, the integer part a increases by 1, so relative to Figure 10 , the pole coil with fewer layers in each pole coil 10A, 10B, here, one layer of concentric coil is added to the first pole coil 10A, and can be expressed as 1-1 / 2&((2n-1) / 2n)-(1 / 2n). Figure 12 In the case of the motor M with Nspp=3.5, Figure 11 Compared to the simplest mixed number, the integer part a increases by 1, so relative to Figure 11 , for the pole coil with fewer layers in each pole coil 10A, 10B, one layer of concentric coil is added to the second pole coil 10B, and can be expressed as 1-1 / 2&1-((2n-1) / 2n)-(1 / 2n). Figure 13 In the case of the motor M with Nspp=4.5 shown in the figure, Figure 12 Compared to the simplest mixed number, the integer part a increases by 1, so relative to Figure 12For the pole coil with the fewer layers in each pole coil 10A or 10B, here, the first pole coil 10A, an additional concentric coil layer is added, which can be expressed as 1-1-1 / 2 & 1-((2n-1) / 2n)-(1 / 2n). In this way, in the case of a motor M with a fractional slot structure, a common rule can be used to express the concentric winding structure.

[0119] Next, the motor M with an integer slot structure is described. Figure 14 In the case of the motor M with Nspp=1, it becomes 1 / n & ((n-2) / n)-(1 / n). For example, in the case of m1=1, m2=1, and m3=1, n=3, which can be expressed as 1 / 3 & 1 / 3-1 / 3. Figure 15 In the case of the motor M with Nspp=2, ((n-1) / n)-(1 / n) & ((n-1) / n)-(1 / n) For example, when m1=1, m2=1, and m3=1, n=3, which can be expressed as 2 / 3-1 / 3 & 2 / 3-1 / 3.

[0120] exist Figure 16 In the case of the motor M with Nspp=3, Figure 15 Compared to the simplest mixed number, the integer part a increases by 1, so relative to Figure 15 , as described above, one more concentric coil is added to the pole coil with fewer layers in each pole coil 10A, 10B, but Figure 15 Since the pole coil structures are the same, adding a layer of concentric coil to either one is actually the same. Therefore, here, a layer of concentric coil is added to the second pole coil 10B, and it can be expressed as ((n-1) / n)-(1 / n)&1-((n-1) / n)-(1 / n). Figure 17 In the case of the motor M with Nspp=4, Figure 16 Compared to the simplest mixed number, the integer part a increases by 1, so relative to Figure 16 For the pole coil with the fewer layers in each of the pole coils 10A and 10B, here, for the first pole coil 10A, one concentric coil layer is added, and this can be expressed as 1-((n-1) / n)-(1 / n) & 1-((n-1) / n)-(1 / n). In this way, in the case of a motor M with an integer slot structure, for Nspp = 2 or more, a common rule can be used to express the concentric winding structure.

[0121] (ratio of m1, m2, and m3)

[0122] Since the noise and vibration caused and generated by the fractional slot structure depend on the amplitude of the change in the magnetic attraction between the rotor 2 and the stator 3, the main rotation order of the noise and vibration can be obtained, for example, as follows. Through magnetic field analysis, the magnetic flux density of the gap between the stator 3 and the rotor 2 is obtained, and the time and space distribution of the electromagnetic attraction generated between the stator 3 and the rotor 2 are obtained. Then, the time-space distribution is Fourier expanded, and the spatial component (spatial deformation mode order) and the time component (time order, rotation direction) of the attraction are obtained. The rotation order of noise and vibration is the order obtained by multiplying the spatial deformation mode order by the time order. Among them, the time order is the number of times the spatial deformation of the spatial deformation mode order causes the mechanical angle of the rotor 2 to rotate 360° (in the cylindrical motor M, the rotor 2 rotates one circle) per unit time (1 second).

[0123] Specifically, in an 8-pole, 36-slot motor M (Nspp = 3 / 2, a = 1, b = 1, c = 2), there are 8th, 16th, 32nd, and 40th order rotational noise and vibration. In an 8-pole, 60-slot motor M (Nspp = 5 / 2, a = 2, b = 1, c = 2), there are 8th, 16th, 32nd, 40th, 56th, and 64th order rotational noise and vibration. In an 8-pole, 84-slot motor M (Nspp = 7 / 2, a = 3, b = 1, c = 2), there are 8th, 16th, 32nd, 40th, 56th, 64th, 80th, and 88th order rotational noise and vibration. The 8th and 16th order rotational noise and vibration are considered low order rotational noise, while the other order rotational noise and vibration are considered medium or high order rotational noise.

[0124] exist Figure 18 The figure shows the results of the magnetic attraction amplitude ratio at each spatial deformation mode and time order after the spatiotemporal Fourier analysis of the electromagnetic attraction generated between the stator 3 and the rotor 2 in the motor M with an 8-pole 60-slot fractional slot structure. Here, the figure is based on the rotation order of 8 by replacing (m1, m2, m3, Nt) = (2, 0, 0, 5) ( Figure 7 The ratio of the magnetic attraction amplitude in the radial direction Y of the winding structure) is set to 1. Figure 18, compared to (m1, m2, m3, Nt) = (2, 0, 0, 5), (m1, m2, m3, Nt) = (2, 2, 0, 10) can reduce vibration and noise at the 16th and 8th rotation orders, but has no effect on other rotation orders. On the other hand, compared to (m1, m2, m3, Nt) = (2, 0, 0, 5), (m1, m2, m3, Nt) = (2, 0, 2, 10) cannot reduce vibration and noise at the 16th and 8th rotation orders. Specifically, it can be seen that mixing the first basic phase band group 51 with the second basic phase band group 52, which is offset by a predetermined number of slots (in this embodiment, 7 slots) in the rotational direction X1, achieves a noise and vibration reduction effect for that rotational order. However, mixing the first basic phase band group 51 with the third basic phase band group 53, which is offset by twice the predetermined number of slots (in this embodiment, 14 slots) in the rotational direction X1, achieves no noise and vibration reduction effect for that rotational order. Therefore, the formula (m1, m2, m3, Nt) = (0, 2, 2, 10) also achieves a noise and vibration reduction effect for that rotational order. Based on this, the inventors speculate that the ratio of basic phase band groups (groups with effective phase differences) that are offset by a predetermined number of slots to basic phase band groups (single basic structure) that are not offset by a predetermined number of slots affects the amount of noise and vibration reduction.

[0125] Therefore, the inventors set the theoretical magnetic attraction amplitude ratio (hereinafter referred to as "theoretical ratio") at the 8th rotation order based on the relationship (M-2×Pm) / M (M=m1+m2+m3, Pm is the smaller of (m1+m3) and m2) (the ratio of the number of layers of the individual basic structure of the group that does not become an effective phase difference to the whole layer). In addition, the theoretical ratio at the 16th rotation order is the value obtained by multiplying the theoretical ratio at the 8th rotation order by 0.52 (effectively utilizing the amplitude ratio of the analysis results of the 8th and 16th rotation orders of (m1, m2, m3, Nt)=(2, 0, 0, 5)). Here, Pm is multiplied by 2 because the number of layers m2 of the second basic phase band group 52 and the number of layers m1 of the first basic phase band group 51 having a phase difference of a specified number of slots relative to the second basic phase band group 52 + the number of layers m3 of the third basic phase band group 53 become the same number and are in a relationship offset by the specified number of slots. The value obtained by multiplying the smaller of (m1+m3) and m2 by 2 becomes the total number of layers in a relationship offset by the specified number of slots.

[0126] exist Figure 18 and Figure 22 In the figure, the results of the magnetic attraction amplitude ratio at each rotation order are shown for a motor M with an 8-pole 60-slot fractional slot structure. As mentioned above, the ratio of the magnetic attraction amplitude at each rotation order is (m1, m2, m3, Nt) = (2, 0, 0, 5) ( Figure 7The ratio of the magnetic attraction amplitude in the radial direction Y of the winding structure) is set to 1. In addition to the reference values of (m1, m2, m3, Nt) = (2, 0, 0, 5) and (2, 2, 0, 10), Figure 18 The motor M is in the relationship of m1=m3, Figure 22 The motor M satisfies the relationship m1≠m3.

[0127] Figure 18 The theoretical ratios for the 8th rotation order shown are (m1, m2, m3, Nt) = (2, 0, 0, 5) = 1, (2, 2, 0, 10) = 0, (2, 0, 2, 10) = 1, (4, 2, 4, 25) = 0.6, (2, 2, 2, 15) = 0.33, (4, 6, 4, 35) = 0.14, (2, 4, 2, 20) = 0, (4, 10, 4, 45) = 0.11, (2, 6, 2, 25) = 0.2, (2, 8, 2, 30) = 0.33, and the theoretical ratios for the 16th rotation order are obtained by multiplying their respective values by 0.52 (effectively utilizing the amplitude ratios of the analysis results of the 8th and 16th rotation orders of (m1, m2, m3, Nt) = (2, 0, 0, 5)). Figure 22 The theoretical ratios for the 8th rotation order shown are (2, 0, 0, 5) = 1, (2, 2, 0, 10) = 0, (4, 0, 2, 15) = 1, (4, 2, 2, 20) = 0.5, (8, 6, 4, 45) = 0.33, (4, 4, 2, 25) = 0.2, (8, 10, 4, 55) = 0.09, (4, 6, 2, 30) = 0, (4, 10, 2, 40) = 0.25, and (4, 12, 2, 45) = 0.33. The theoretical ratios for the 16th rotation order are obtained by multiplying their respective values by 0.52 (effectively utilizing the amplitude ratios of the analysis results of the 8th and 16th rotation orders of (m1, m2, m3, Nt) = (2, 0, 0, 5)).

[0128] like Figure 18 As shown in the 8th and 16th order rotation orders, it can be seen that the theoretical ratio is almost consistent with the analysis result. In other words, the arrangement of the three basic phase band groups 51, 52, and 53 with a predetermined number of offset slots in this embodiment (m1, m2, and m3 are all greater than 1) can reduce noise and vibration at low rotation orders (8th and 16th orders). Figure 19 , the results of the torque ratio and torque ripple ratio analysis by magnetic field analysis are shown. As shown in the figure, it can be seen that compared with the comparative example ((m1, m2, m3, Nt) = (2, 0, 0, 5)), the case of setting three basic phase belt groups 51, 52, and 53 in this embodiment with a predetermined number of slots offset each other has less torque loss (less than 2%) and can reduce torque ripple by more than 25%. Similarly, Figures 22 and 23 As shown in the analysis results, even when m1 ≠ m3, noise and vibration can be reduced even at low rotation orders (8th and 16th), with little reduction in torque compared to the comparative example, and torque ripple is reduced. By increasing the number of branches for selecting m1, m2, and m3, the number of branches for selecting the number of series turns in motor M can be increased.

[0129] Next, use Figures 25 and 26 The following describes a motor M with an integer-slot structure and Nspp = 2. As described above, in this motor M, the coil sides 11a of all adjacent mixed-phase bands 50A have the same structure. Therefore, the center-to-center distances between the coil sides 11a of adjacent mixed-phase bands 50A of the same phase (U phase) are constant, maintaining the rotational symmetry of the magnetic force distribution. Consequently, this symmetry minimizes the impact of noise and vibration on the motor M. Therefore, the impact of torque ripple caused by the windings on this motor M will be examined.

[0130] exist Figure 25 The results of analyzing the torque and torque ripple by magnetic field analysis are shown in FIG. 1 , which is an integer slot structure motor M with 8 poles and 48 slots. Here, the figure shows the ratio of the torque and torque ripple when (m1, m2, m3, Nt) = (1, 0, 0, 2) is set to 1. Figure 25 , compared to (m1, m2, m3, Nt) = (1, 0, 0, 2), (m1, m2, m3, Nt) = (1, 1, 0, 4), torque ripple can be reduced. On the other hand, compared to (m1, m2, m3, Nt) = (1, 0, 0, 2), (m1, m2, m3, Nt) = (1, 0, 1, 4), torque ripple cannot be reduced. Specifically, it can be seen that mixing the first basic phase belt group 51 with the second basic phase belt group 52, which is offset by a predetermined number of slots (in this embodiment, one slot) in the rotation direction X1, has a torque ripple reduction effect. However, mixing the first basic phase belt group 51 with the third basic phase belt group 53, which is offset by twice the predetermined number of slots (in this embodiment, two slots) in the rotation direction X1, has a lesser torque ripple reduction effect. Therefore, the torque ripple reduction effect can also be achieved when (m1, m2, m3, Nt) = (0, 1, 1, 4). The present inventors therefore speculate that the ratio of the basic phase band group (the group with an effective phase difference) that is offset by a predetermined number of slots to the basic phase band group (the independent basic structure) that is not offset by the predetermined number of slots affects the amount of torque ripple reduction.

[0131] Therefore, the present inventors set a theoretical torque ripple ratio (hereinafter referred to as the "theoretical ratio") based on the relationship (M-2×Pm) / M (where M=m1+m2+m3, and Pm is the smaller of (m1+m3) and m2) (the ratio of the number of layers of the individual basic structures that do not constitute a group with an effective phase difference to the total number of layers). Here, Pm is multiplied by 2 because the number of layers m2 of the second basic phase belt group 52 and the number of layers m1 of the first basic phase belt group 51 having a phase difference of a predetermined number of slots relative to the second basic phase belt group 52 + the number of layers m3 of the third basic phase belt group 53 are the same number, but are offset by the predetermined number of slots. The value obtained by multiplying the smaller of (m1+m3) and m2 by 2 is the total number of layers, which is offset by the predetermined number of slots.

[0132] As described above, the ratio of the case where the torque ripple of (m1, m2, m3, Nt) = (1, 0, 0, 2) is set to 1 is expressed. In addition to the reference values of (m1, m2, m3, Nt) = (1, 0, 0, 2) and (1, 1, 0, 2), Figure 25 The motor M is in the relationship of m1=m3, Figure 26 The motor M satisfies the relationship m1≠m3.

[0133] Figure 25 The theoretical ratio of the torque fluctuation shown is (m1, m2, m3, Nt) = (1, 0, 0, 2) = 1, (1, 1, 0, 4) = 0, (1, 0, 1, 4) = 1, (2, 1, 2, 10) = 0.6, (1, 1, 1, 6) = 0.33, (1, 2, 1, 8) = 0, (1, 4, 1, 12) = 0.33, (1, 5, 1, 14) = 0.43, (1, 7, 1, 18) = 0.56. Figure 26 The theoretical ratios of the torque fluctuations shown are (1, 0, 0, 2) = 1, (1, 1, 0, 4) = 0, (2, 0, 1, 6) = 1, (2, 1, 1, 8) = 0.5, (2, 2, 1, 10) = 0.2, (2, 3, 1, 12) = 0, (2, 4, 1, 14) = 0.14, (2, 6, 1, 18) = 0.33, and (2, 7, 1, 20) = 0.40.

[0134] like Figure 25 As shown in the torque fluctuation, it can be seen that the theoretical ratio and the analysis result have similar trends. That is, in addition, when the three basic phase belt groups 51, 52, and 53 are set with a predetermined number of slots offset in this embodiment (m1, m2, and m3 are all 1 or more), the torque fluctuation is reduced by more than 30%, and the torque loss is less (less than 10%) compared with the comparative example ((m1, m2, m3, Nt) = (1, 0, 0, 2)). Similarly, as Figure 26As shown in the analysis results, torque ripple is reduced even when m1 ≠ m3, and torque is barely reduced compared to the comparative example. This shows that the regulations for m1, m2, and m3 related to noise and vibration in the fractional-slot motor M can be directly applied to the regulations for m1, m2, and m3 related to torque ripple in the integer-slot motor M.

[0135] The present inventors have investigated simpler definitions of m1, m2, and m3 that can reduce noise and vibration in fractional-slot motors M and torque ripple in integer-slot motors M. Therefore, focusing on the ratio of the number of layers m2 in the second basic phase-belt group 52 to the number of layers m1 in the first basic phase-belt group 51 + the number of layers m3 in the third basic phase-belt group 53 (2×m2 / (m1+m3), the ratio of the number of layers with an effective phase difference), it is assumed that a uniform range of values can be defined to reduce noise and vibration in fractional-slot motors M and torque ripple in integer-slot motors M. If this assumption is correct, variations in m1, m2, and m3 can be set to achieve useful performance improvements, regardless of the integer portion a of Nspp, the relationship between m1, and m3.

[0136] This assumption is supplemented. The quantity involved in the change in the ratio (m1, m2, m3) is the turns ratio n = M / m1 (M = m1 + m2 + m3) of the unit coil 11 constituting the aforementioned concentric winding. As already mentioned, in the concentric winding configuration, the turns ratio of the inner and outer coils in one of the pole-pair coils 10 in the fractional-slot motor M and both pole-pair coils 10 in the integer-slot motor M is determined by n. Therefore, the change in the characteristics of the motor M caused by the change in the ratio (m1, m2, m3) is due to the change in the winding structure. The specific content of the winding structure change, when expressed in terms of a concentric winding structure, can be interpreted as a change in the turns ratio of the inner and outer coils. The turns ratio n of the unit coil 11 constituting the concentric winding is treated as an amount that contributes to noise and vibration in the fractional-slot motor M and torque ripple in the integer-slot motor M. However, for n = M / m1, the appropriate range of n varies depending on the slot configuration (fractional or integer), the integer portion a of Nspp, and the relationship between m1 and m3, making the definition complicated. On the other hand, based on the above assumption, 2×m2 / (m1+m3) becomes n×m1 / (m1+m3)-2, a quantity related to n. This is a more general proportional quantity that can be uniformly handled regardless of the slot configuration (fractional or integer), the integer portion a of Nspp, and the relationship between m1 and m3. Based on this insight, it was discovered that a useful variation of (m1, m2, m3) can be easily set based on the relationship between m1, m2, and m3 such that 2×m2 / (m1+m3) > 0, which is effective for improving the characteristics of motor M.

[0137] exist Figure 20 、 Figure 21 as well as Figure 24 In the figure, the analysis results are shown with the ratio 2×m2 / (m1+m3) as the horizontal axis and the noise and vibration, torque, and torque ripple of each low-order rotation order in the fractional slot structure motor M as the vertical axis. Figures 25 and 26 , in the motor M with an integer slot structure, the analysis results are shown, with the ratio 2×m 2 / (m 1 +m 3) as the horizontal axis and the torque and torque ripple as the vertical axis.

[0138] like Figure 20 and Figure 21 (m1=m3), Figure 24 As shown in (m1≠m3), it can be seen that in the motor M with a fractional slot structure, there is a range of 2×m2 / (m1+m3) suitable for reducing noise and vibration of each low-order rotation order. In addition, with regard to torque, the larger 2×m2 / (m1+m3), that is, the larger the ratio of the number of layers m2 of the second basic phase band group 52 of the basic phase band structure as one phase becomes, the more asymptotically it approaches the state of (m1, m2, m3)=(0, 1, 0), so it is easy to understand that the torque tends to increase with the torque ratio 1. Thus, while ensuring the desired torque, the amplitude ratio of the magnetic attraction of the low-order rotation order and the range of the torque fluctuation can be reduced to 1≤2×m2 / (m1+m3)≤4. Specifically, as Figure 20 and Figure 21 As shown, the torque loss can be reduced to about 1% or less, while the amplitude ratio of the magnetic attraction force of the low-order rotation order can be reduced to about 1 / 3 or less, and the torque ripple can also be improved by about 20% or more.

[0139] like Figures 25 and 26 As shown, the range of 1≤2×m2 / (m1+m3)≤4 is also the range in which torque ripple can be reduced while ensuring the desired torque in the motor M with an integer slot structure. In this way, if 1≤2×m2 / (m1+m3)≤4, both fractional slots and integer slots can reduce torque ripple while roughly maintaining the desired torque. Moreover, in fractional slots, noise and vibration can also be reduced. Figure 27The figure shows the relationship between the ratio 2×m2 / (m1+m3), which improves the performance of motor M as described above, and the number of series-connected turns Nt. As shown in the figure, in this embodiment, by defining the ratio 2×m2 / (m1+m3) within a range, the options for selecting m1, m2, and m3 are increased, thereby increasing the options for selecting the number of series turns in motor M that achieves improved performance (reduced torque ripple, reduced noise, and vibration). This allows the number of series turns required based on other factors (such as output characteristics, applied voltage, applied current, and motor size) to be set to values that are consistent with or close to the number of series turns required to achieve the aforementioned performance improvement, achieving the aforementioned performance improvement while satisfying the other factors. On the other hand, without this insight, the options for selecting the number of series turns that achieves the aforementioned performance improvement are limited, resulting in a large difference between the number of series turns required based on the other factors and the number of series turns required, often resulting in only one of the other factors being satisfied or the aforementioned performance improvement being satisfied. In this case, for example, if the number of turns connected in series is selected as the performance improvement, other requirements may not be met, and as a countermeasure, the size of the motor M must be increased. If the size of the motor M is limited, the performance improvement cannot be achieved.

[0140] (skew structure)

[0141] Figure 28 The figure shows an example of the magnetic pole-to-pole relationship between a plurality of teeth 31b and the magnetic poles (N pole and S pole) of a pair of rotors 2 in an 8-pole, 60-slot motor M, which is a comparative example without skew. In this figure, the annular stator core 31 is unfolded into a straight line and shown as the stator core 31 when viewed in the axial direction Z. In addition, in this figure, the yoke 31a and the winding are omitted, and the identification number of the stator magnetic pole formed in the stator core 31 (hereinafter referred to as the stator magnetic pole number T_No.) is marked on each tooth 31b. In addition, for ease of explanation, the center position of the slot 32 between the stator magnetic pole number T_No of 60 and the stator magnetic pole number T_No of 1 is set as the position reference of the magnetic pole of the pair of rotors 2 (the position coordinate PP is 0).

[0142] like Figure 28 As shown, one end 22a of the two ends 22a and 22b of the north pole in the circumferential direction X (position coordinate PP is 0) is opposite the center position of the slot 32. In contrast, the other end 22b of the north pole (position coordinate PP is 7.5) is opposite the center position of the tooth 31b. Therefore, the magnetic pole center position (position coordinate PP is 3.75) is arranged to be offset in the rotation direction X1 relative to the center position of the tooth 31b (the tooth 31b with stator magnetic pole number T_No is 4).

[0143] In this case, the electromagnetic attractive force distribution in the radial direction Y acting on the plurality of teeth 31b (hereinafter also referred to as "attractive force distribution") is obtained by Figure 28 The bar graph represents the distribution. Figure 28 An example of the distribution of electromagnetic attractive force acting on multiple teeth 31b in the radial direction Y in a motor of a comparative example is shown. The vertical axis represents the magnitude of the attractive force PSU, and the horizontal axis represents the circumferential direction X. The motor of the comparative example differs from the motor M of this embodiment in that the rotor 2 does not have a continuous skewed portion 42, described later.

[0144] The attractive force distribution acting on the multiple teeth 31b can be obtained through magnetic field analysis. The solid line L11 represents the approximate straight line of the attractive force distribution represented by the bar graph. As shown in the figure, the peak of the attractive force distribution of the stator magnetic pole is offset relative to the center position of the rotor's N pole in the rotation direction X1. The magnetic pole-facing state that produces this attractive force distribution is referred to as magnetic pole-facing state M10.

[0145] One end 22c of the S-pole's two ends 22c and 22d in the circumferential direction X (position coordinate PP = 7.5) faces the center of tooth 31b. Conversely, the other end 22d of the S-pole (position coordinate PP = 15) faces the center of slot 32. Therefore, the magnetic pole center position (position coordinate PP = 11.25) is offset in the counter-rotational direction X2 relative to the center of tooth 31b (tooth 31b with stator magnetic pole number T_No = 12).

[0146] In this case, the attractive force acting on the plurality of teeth 31b is distributed as follows Figure 28 The bar graph shows the distribution of the attractive force for each stator magnetic pole. Solid line L12 represents a straight line approximating the distribution of the attractive force for each stator magnetic pole, as shown by the bar graph. As shown in this figure, the peak of the attractive force distribution for the stator magnetic pole is offset in the rotational direction X1 relative to the center position of the rotor's S pole. The magnetic pole-opposing state that produces this attractive force distribution is referred to as magnetic pole-opposing state M11.

[0147] Thus, in the 1 / 2 series (c=2) motor M, there are two magnetic pole opposing states M10 and M11, and two attractive force distributions. Therefore, a pair of adjacent rotor poles in the circumferential direction X have different attractive force distributions. As a result, the attractive force distribution acting on the multiple teeth 31b is not equivalent for each magnetic pole, but is equivalent for every other pole within each magnetic pole pair (every two magnetic poles).

[0148] The two attractive force distributions (two magnetic pole opposing states M10 and magnetic pole opposing states M11) are substantially symmetrical with respect to the mirror plane 33. The mirror plane 33 is a virtual reference plane formed by the radial direction Y and the axial direction Z. If the solid line L11 is folded back with respect to the mirror plane 33, it will substantially coincide with the solid line L12. Figure 28 The dotted line L13 represents a line formed by moving the solid line L11 in parallel along the circumferential direction X by the size of one magnetic pole of the rotor 2. Figure 28 The region enclosed by the dotted line shows the difference in the magnetic pole-facing state between the teeth 31 b and a pair of magnetic poles.

[0149] The two attraction force distributions (two magnetic pole opposing states M10 and magnetic pole opposing states M11) have components of exciting forces of a lower order (in this embodiment, the 4th order of the spatial deformation mode) than the order (in this embodiment, the 8th order of the spatial deformation mode) depending on the number of poles of the rotor 2 (in this embodiment, 8 poles).

[0150] Figure 29 An example of a magnetic pole facing state between a plurality of teeth 31b and a pair of magnetic poles of the rotor 2 in this embodiment is shown. Figure 28 The method of illustrating is different. As a difference, Figure 29 In this figure, the gap between the stator 3 and the rotor 2 is used as the boundary, and the diagramming method is switched. In this figure, the stator 3 is shown above the boundary when viewed in the axial direction Z, and the rotor 2 is shown below the boundary when viewed in the radial direction Y. This is a simplified diagram to clearly illustrate the relationship between the continuous skew applied to the rotor 2 and the circumferential position of the stator 3 in the X direction.

[0151] like Figure 29 As shown, the rotor 2 of this embodiment includes a first reference portion 41 (an example of a reference portion) and a continuously skewed portion 42 (an example of a skewed portion). The first reference portion 41 is a reference portion, serving as a reference for skew. The continuously skewed portion 42 is a skewed portion, gently offset in the circumferential direction X relative to the first reference portion 41 and disposed in the axial direction Z. The continuously skewed portion 42 is gently offset in the rotational direction X1 of the circumferential direction X relative to the first reference portion 41 and disposed in the axial direction Z.

[0152] While the figure illustrates the first reference portion 41 and the continuously skewed portion 42 using a pair of magnetic poles of the rotor 2 as an example, they are similarly formed in the rotor core 21. Specifically, the plurality of electromagnetic steel sheets (the continuously skewed portion 42) forming the rotor core 21 are arranged (stacked) in the axial direction Z, gradually offset in the rotational direction X1 of the circumferential direction X relative to the single electromagnetic steel sheet (the first reference portion 41) forming the rotor core 21.

[0153] Furthermore, the continuous deflection portion 42 is divided into two equal parts along the circumferential direction X by a plane perpendicular to the axial direction Z. The first continuous deflection portion 42a and the second continuous deflection portion 42b are defined in order from the portion on the first reference portion 41 side. Figure 29 In the figure, for ease of explanation, the continuously deflected portion 42 is shown as a separate first continuously deflected portion 42a and a second continuously deflected portion 42b; however, the continuously deflected portion 42 is formed as a single unit. Furthermore, in this figure, the first reference portion 41 represents one end surface of the pair of magnetic poles in the axial direction Z. Furthermore, of the two end surfaces of the second continuously deflected portion 42b in the axial direction Z, the end surface on the side opposite to the boundary between the first continuously deflected portion 42a and the second continuously deflected portion 42b represents the other end surface of the pair of magnetic poles in the axial direction Z.

[0154] In this embodiment, the continuous skew portion 42 is set to have a maximum skew relative to the first reference portion 41, so that the maximum relative skew between the stator 3 and the rotor 2 is converted to the same value as one slot pitch of the stator core 31. Specifically, the rotor 2 includes the first reference portion 41 and the continuous skew portion 42, while the stator 3 does not. Therefore, the skew in the stator 3 is zero, while the maximum skew in the continuous skew portion 42 of the rotor 2 relative to the first reference portion 41 is set to one slot pitch.

[0155] Specifically, if Figure 29 As shown, the pair of magnetic poles at the boundary between the first continuously skewed portion 42a and the second continuously skewed portion 42b are offset by half the slot pitch relative to the first reference portion 41 in the rotational direction X1 of the circumferential direction X. Furthermore, the end surfaces of the pair of magnetic poles on the other side of the axial direction Z are offset by one slot pitch relative to the first reference portion 41 in the rotational direction X1 of the circumferential direction X. Furthermore, the motor M in this embodiment has an 8-pole, 60-slot structure, and one slot pitch corresponds to an electrical angle of 24° (360° / 15 slots).

[0156] One end 22a (position coordinate PP = 0) of the north pole of the first reference portion 41 in the circumferential direction X is aligned with the center of the slot 32. The other end 22b (position coordinate PP = 7.5) of the north pole of the first reference portion 41 is aligned with the center of the tooth 31b. The center of the north pole of the first reference portion 41 (position coordinate PP = 3.75) is offset in the rotational direction X1 relative to the center of the tooth 31b (the tooth 31b with stator magnetic pole number T_No = 4).

[0157] At the boundary between the first continuously skewed portion 42a and the second continuously skewed portion 42b, one end 22a (position coordinate PP = 0.5) of the north pole's two ends in the circumferential direction X is aligned with the center of the tooth 31b. The other end 22b (position coordinate PP = 8) of the north pole is aligned with the center of the slot 32. In this case, the center of the north pole (position coordinate PP = 4.25) is offset in the counter-rotational direction X2 in the circumferential direction X relative to the center of the tooth 31b (the tooth 31b with stator magnetic pole number T_No = 5).

[0158] The separation point in the circumferential direction X, represented by the denominator c of the number of slots per pole per phase Nspp, is defined as a separation point that is 1 / c of the slot pitch (in this embodiment, 1 / 2 of the slot pitch). Specifically, the separation point is defined as the point at position coordinate PP = 3.75 and the point at position coordinate PP = 4.25. The above description regarding the separation point at position coordinates PP = 3.75 and PP = 4.25 also applies to other separation points in the axial direction Z.

[0159] Figure 30 It is for use Figure 29 A schematic diagram illustrating the state of magnetic pole opposition in the area surrounded by the dotted line. The circles in the figure represent the separation parts represented by position PC1 (position coordinate PP = 3.75) and position PC2 (position coordinate PP = 4.25). The square marks represent the separation parts represented by position PD1 (position coordinate PP = 4) and position PD2 (position coordinate PP = 4.5). The triangle marks represent the separation parts represented by position PE1 (position coordinate PP = 4.25) and position PE2 (position coordinate PP = 4.75). As shown in the figure, these separation parts are located on the dotted line representing the center position of the N pole. Between any separation parts, the above contents also apply to the separation parts represented by position PC1 (position coordinate PP = 3.75) and position PC2 (position coordinate PP = 4.25).

[0160] The same applies to separations other than those shown. That is, the same relationship as described above (the relationship between separations separated by 1 / 2 the slot pitch in the circumferential direction X) holds true throughout the entire axial direction Z of the rotor 2. Furthermore, the pole-facing state shown in the figure repeats in the circumferential direction X, with each slot pitch serving as a unit, as the rotor 2 moves (the center position of the magnetic poles of the rotor 2 moves by an integral multiple of one slot pitch).

[0161] Between the separation parts (in Figure 30In the example shown, for example, between the circled areas, the squared areas, and the triangular areas, components of the excitation force of a lower order (in this embodiment, the 4th order in the spatial deformation mode) than the order (in this embodiment, the 8th order in the spatial deformation mode) determined by the number of magnetic poles of the rotor 2 (in this embodiment, 8 poles) are spatially offset by half a wavelength in the axial direction Z and overlap, improving the balance within each rotor pole. As a result, these attractive force distributions are raised to the same level as those of the motor M with the same number of rotor poles and an integer slot structure (the 8th order in the spatial deformation mode). This allows the rotational speed to be increased to match the natural vibration frequency of the stator core 31, for example, to be set outside the operating speed range. That is, since the motor M of this embodiment can avoid the chance of resonance of the stator 3 within the operating speed range, the noise and vibration of the motor M can be reduced.

[0162] Furthermore, if the maximum amount of deflection relative to the first reference portion 41 is not set to one slot pitch, a region will occur where the aforementioned relationship (the relationship between the portions separated by half the slot pitch in the circumferential direction X) does not hold. As a result, low-order (in this embodiment, the fourth-order spatial deformation mode) excitation force components remain in this region, making it difficult to achieve mixing, averaging, and balancing of the attractive force distribution throughout the entire axial direction Z of the rotor 2.

[0163] Figure 29 An example of the electromagnetic attraction distribution in the radial direction Y acting on multiple teeth 31b obtained by magnetic field analysis is shown. The vertical axis represents the magnitude PSU of the attraction, and the horizontal axis represents the circumferential direction X. The solid line L21 represents an approximate straight line of the attraction distribution represented by a bar graph approximated by a straight line. The figure shows an attraction distribution (attraction distribution of an integer slot structure) that is equivalent to the peak value of the attraction in each pole by mixing, averaging and equalizing the above-mentioned attraction distribution. In addition, the attraction spacing LP0 represents the interval of the peak value of the attraction in the circumferential direction X. The attraction spacing LP0 is balanced in each pole with a slot spacing of 7.5, which is consistent with the rotor pole spacing (7.5 slot spacing).

[0164] The continuous deflection portion 42 preferably has a constant rate of increase or decrease in the amount of deflection relative to the first reference portion 41 from one end toward the other end in the axial direction Z. When the continuous deflection portion 42 is offset relative to the first reference portion 41 in the rotational direction X1, the amount of deflection of the continuous deflection portion 42 increases. Conversely, when the continuous deflection portion 42 is offset relative to the first reference portion 41 in the counter-rotational direction X2, the amount of deflection of the continuous deflection portion 42 decreases.

[0165] like Figure 30As shown, according to the motor M of this embodiment, the continuous skew portion 42 is configured to increase the skew relative to the first reference portion 41 at a constant rate from one end toward the other in the axial direction Z. For example, between position PC1 (position coordinate PP = 3.75) and position PC2 (position coordinate PP = 4.25), the skew relative to position PC1 (position coordinate PP = 3.75) increases by half the slot pitch. Furthermore, between position PC2 (position coordinate PP = 4.25) and position PC3 (position coordinate PP = 4.75), the skew relative to position PC2 (position coordinate PP = 4.25) increases by half the slot pitch. In this way, the skew increases uniformly at a constant rate from position PC1 (position coordinate PP = 3.75) to position PC3 (position coordinate PP = 4.75).

[0166] As described above, since the rate of increase in the skewness of the continuously skewed portion 42 relative to the first reference portion 41 is set constant from one end toward the other in the axial direction Z, leakage magnetic flux in the axial direction Z can be reduced compared to a case where the skewness relative to the first reference portion 41 varies discontinuously. This also simplifies the rotor structure and manufacturing process. The same applies to a case where the rate of decrease in the skewness relative to the first reference portion 41 is set constant. In this case, the continuously skewed portion 42 is disposed in the axial direction Z, gradually offset in the counter-rotational direction X2 in the circumferential direction X relative to the first reference portion 41.

[0167] As described above, the continuously skewed portion 42 in this embodiment is gradually offset in the circumferential direction X relative to the first reference portion 41 and arranged in the axial direction Z. Furthermore, the maximum amount of deviation of the continuously skewed portion 42 relative to the first reference portion 41 is set to one slot pitch. Therefore, any portion of the rotor 2 in the circumferential direction X is widened by one slot pitch in the circumferential direction X and faces the stator 3. This gradually changes the magnetic field at the opening of the slots 32 of the stator 3, thereby reducing torque ripple.

[0168] Furthermore, in the fractional-slot motor M, since different magnetic pole-opposing states are repeated in the circumferential direction X, torque ripple tends to be reduced compared to rotating electrical machines with integer-slot structures. According to the motor M of this embodiment, since the rotor 2 includes the continuous skew portion 42, torque ripple caused by the magnetic pole-opposing state between the stator and rotor poles is further reduced. Furthermore, according to the motor M of this embodiment, since the rotor 2 includes the continuous skew portion 42, abrupt changes in magnetic flux can be suppressed, thereby reducing iron loss, magnet eddy current loss, and copper eddy current loss.

[0169] As described in non-patent document 1, in order to reduce the higher harmonic components, a continuous skew of 1 / c (c is the denominator of the number of slots per pole per phase) slot pitch of the stator 3 is implemented (the maximum value of the skew relative to the first reference portion 41 is set to 1 / c slot pitch), or a simplified version of a step skew (circumferential offset 1 / (2×c) slot pitch) is implemented. The same effect can be achieved by a continuous skew of nq / c slot pitch (nq is a natural number) of the stator 3. The larger the natural number nq, the greater the torque loss of the motor M. In addition, there is a tendency for manufacturing to become more complicated. Therefore, 1 is usually selected as the natural number nq. However, since this cannot improve the deterioration of the magnetic periodicity between the rotor 2 and the stator 3 mentioned above, it is impossible to reduce the noise and vibration of the spatial deformation mode of a lower order than the number of rotor poles. On the other hand, in this embodiment, in the fractional slot motor M, the continuous skew portion 42 is set to have a maximum skew relative to the first reference portion 41 (in this embodiment, one slot pitch, i.e., nq = c = 2). This allows the maximum relative skew between the stator 3 and the rotor 2 to be converted to one slot pitch of the stator core 31 using the continuous skew. Specifically, 2 is selected as the natural number nq. This reduces noise and vibration in the motor M while also reducing torque ripple and higher harmonic components in the output waveform.

[0170] Another method for reducing noise, vibration, and torque ripple in the motor M is to provide cutouts at the tips of the teeth of the stator core 31 or on the surface (outer surface) of the rotor core 21 that faces the tips of the teeth. However, this method effectively enlarges the gaps, increasing torque loss compared to the aforementioned skew. The motor M of this embodiment can suppress torque loss and reduce noise, vibration, and torque ripple in the motor M.

[0171] Although not shown, as a modified example, the stator 3 may include a first reference portion 41 and a continuously skewed portion 42. Specifically, the plurality of electromagnetic steel sheets forming the stator core 31 (the continuously skewed portion 42) are gradually offset in the counter-rotational direction X2 in the circumferential direction X relative to the single electromagnetic steel sheet forming the stator core 31 (the first reference portion 41) and arranged (stacked) in the axial direction Z.

[0172] Although not shown, as another modified example, both the stator 3 and the rotor 2 may include a first reference portion 41 and a continuously skewed portion 42. Specifically, the stator 3 includes a first reference portion 41 and a continuously skewed portion 42 offset from the first reference portion 41 in the rotational direction X1. The continuously skewed portion 42 has a maximum skew relative to the first reference portion 41 of 1 / 2 the slot pitch. The rotor 2 includes a first reference portion 41 and a continuously skewed portion 42 offset in the counter-rotational direction X2. The continuously skewed portion 42 has a maximum skew relative to the first reference portion 41 of 1 / 2 the slot pitch. Thus, the maximum relative skew between the stator 3 and the rotor 2 is converted to one slot pitch of the stator core 31 using the continuous skew.

[0173] The motor M of this modification can reduce the skew between the stator 3 and the rotor 2 compared to the case where only one of the stator 3 and the rotor 2 is skewed. As a result, leakage flux can be reduced, and torque loss can be suppressed.

[0174] Furthermore, according to the motor M of this modified example, the maximum skew amount in the continuously skewed portion 42 of the stator 3 and the maximum skew amount in the continuously skewed portion 42 of the rotor 2 are set to the same value (half the slot pitch). Thus, the motor M of this modified example can evenly distribute the skew amount between the stator 3 and the rotor 2, thereby alleviating the complexity of manufacturing the stator 3 and rotor 2 associated with the skew, thereby improving workability during the manufacturing process.

[0175] (Another embodiment 1)

[0176] Another embodiment 1 is different in that the first reference portion 41 includes a first reference portion 41a on one end side in the axial direction Z (an example of a reference portion) and a first reference portion 41b on the other end side in the axial direction Z (an example of a reference portion), and the continuous deflection portion 42 includes a continuous deflection portion 45a on one end side (an example of a deflection portion) and a continuous deflection portion 45b on the other end side (an example of a deflection portion).

[0177] Figure 31 This figure shows an example of the skew of the stator 3 when viewed in the radial direction Y. In this embodiment, the amount of skew in the rotor 2 is zero. Therefore, the skew position of the stator 3 is formed along the axial direction Z. Straight line 51 represents the skew position of the stator 3 at the reference position P_ref, with one end in the axial direction Z aligned with the other end in the circumferential direction X.

[0178] Use the same Figure 31An example of skew in the rotor 2 will be described. In this case, the amount of skew in the stator 3 is zero. In this embodiment, the rotor 2 also includes a first reference portion 41 and a continuous skew portion 42. In this embodiment, the first reference portion 41 includes a first reference portion 41a on one end and a first reference portion 41b on the other end.

[0179] Furthermore, the continuously skewed portion 42 includes a one-end continuously skewed portion 45a and a second-end continuously skewed portion 45b. The one-end continuously skewed portion 45a is a portion located halfway along the one-end side in the axial direction Z, gradually offset from the one-end first reference portion 41a in the rotational direction X1 and disposed toward the center portion 46 in the axial direction Z. The second-end continuously skewed portion 45b is a portion located halfway along the other-end side in the axial direction Z, gradually offset from the center portion 46 in the counter-rotational direction X2 in the circumferential direction X and disposed toward the second-end first reference portion 41b. Furthermore, in this embodiment, the reference position P_ref of the stator 3 coincides with the reference position P_ref of the rotor 2 (the reference position of the one-end first reference portion 41a and the reference position of the second-end first reference portion 41b).

[0180] The maximum skew of the one-end continuous skew portion 45a relative to the one-end first reference portion 41a is set to one slot pitch. A straight line 55a represents the skew position of the rotor 2, connecting the reference position P_ref at one end in the axial Z direction to a position separated by one slot pitch from the reference position P_ref at the center portion 46 in the axial Z direction. Similarly, the maximum skew of the other-end continuous skew portion 45b relative to the other-end first reference portion 41b is set to one slot pitch. A straight line 55b represents the skew position of the rotor 2, connecting a position separated by one slot pitch from the reference position P_ref at the center portion 46 in the axial Z direction to the reference position P_ref at the other end in the axial Z direction. Consequently, the relative skew between the stator 3 and rotor 2 is maximized at the center portion 46 in the axial Z direction of the stator 3 and rotor 2. This maximum relative skew between the stator 3 and rotor 2 is converted to one slot pitch of the stator core 31 using the continuous skew.

[0181] According to the motor M of this embodiment, the rotor 2 includes a first reference portion 41 and a continuously skewed portion 42. The first reference portion 41 includes a first reference portion 41a on one end and a first reference portion 41b on the other end. The continuously skewed portion 42 includes a continuously skewed portion 45a on one end and a continuously skewed portion 45b on the other end. Furthermore, the first reference portion 41 and the central portion 46 in the axial direction Z are designed so that the maximum relative skew between the stator 3 and the rotor 2, converted from the continuous skew, is equivalent to the pitch of one slot in the stator core 31. Consequently, the motor M of this embodiment can achieve the same effects as those of the aforementioned embodiments.

[0182] Furthermore, the rate of increase in the deflection of the one-end continuous deflection portion 45a relative to the one-end first reference portion 41a is set constant from the one end side toward the center portion 46 in the axial direction Z, while the rate of decrease in the deflection of the other-end continuous deflection portion 45b relative to the other-end first reference portion 41b is set constant from the center portion 46 in the axial direction Z toward the other end. Furthermore, the absolute value of the rate of increase in the deflection is preferably set to the same value as the absolute value of the rate of decrease in the deflection. This reduces magnetic flux leakage compared to a case where the deflection relative to the first reference portion 41 (the one-end first reference portion 41a and the other-end first reference portion 41b) varies discontinuously. Furthermore, the manufacturing process can be simplified.

[0183] Furthermore, since the continuous skew portion 42 in this embodiment includes a continuous skew portion 45a on one end and a continuous skew portion 45b on the other end, fold symmetry about the center portion 46 in the axial direction Z can be ensured, thereby reducing torsional resonance. Furthermore, when the permanent magnet 22 is a sintered magnet, there is a possibility that workability will deteriorate when the permanent magnet 22 is installed in the magnet housing portion of the rotor core 21. In this case, the permanent magnet 22 can also be divided into two equal parts along the circumferential direction X using a plane perpendicular to the axial direction Z. By installing one of the divided permanent magnets 22 from one end in the axial direction Z and installing the other divided permanent magnet 22 from the other end in the axial direction Z, the aforementioned deterioration in workability can be reduced.

[0184] In addition, in the present embodiment, the distance in the axial direction Z of the separation portion (the portion separated by 1 / 2 slot pitch in the circumferential direction X) in the above-mentioned embodiment is roughly halved. Therefore, in the present embodiment, since the higher order of the attractive force distribution is achieved at a closer distance, it works more effectively. In addition, the present embodiment is also preferred when the axial length (the dimension in the axial direction Z) of the stator 3 and the rotor 2 is increased. Furthermore, the structure of the present embodiment can also be used repeatedly in the axial direction Z. In addition, in the continuous deflection portion 42, the number of portions that are gradually offset in the rotation direction X1 and the number of portions that are gradually offset in the counter-rotation direction X2 in the circumferential direction X can also be different. These can be appropriately selected according to the composition of the motor M, the required specifications, etc.

[0185] (Another embodiment 2)

[0186] Another embodiment 2 differs from the above-mentioned embodiment in that the stator 3 includes a first reference portion 41 (an example of a reference portion) and a continuous skew portion 42, and the rotor 2 includes a second reference portion 43 (an example of a reference portion) and a step skew portion 44 (an example of a skew portion).

[0187] Figure 32The figure shows the skew of the stator 3 and rotor 2. The rotor 2 is an inner rotor type, located on the inner circumference of the stator 3. The figure shows the skew when the stator 3 is viewed from the inner circumference of the stator 3 and the rotor 2 is viewed from the outer circumference of the rotor 2. Therefore, the skew directions X1 and X2 of the stator 3 are opposite to the skew directions of the rotor 2. To illustrate this, the stator 3 is shown with a dotted line, and the rotor 2 is shown with a solid line. Figure 32 The dashed line represents an example of the skew state of the stator 3. In this embodiment, the stator 3 includes a first reference portion 41 and a continuously skewed portion 42. Therefore, the skew position of the stator 3 shifts from one end toward the other end in the axial direction Z according to the amount of skew. The continuously skewed portion 42 is gradually offset relative to the first reference portion 41 in the counter-rotational direction X2 in the circumferential direction X and is disposed in the axial direction Z. The maximum amount of skew relative to the first reference portion 41 is set to half the slot pitch.

[0188] Figure 32 The solid line represents an example of the skew state of the rotor 2. In this embodiment, the rotor 2 includes a second reference portion 43 and a stepped skew portion 44. The second reference portion 43 is a reference portion, which refers to a portion that serves as a reference for the skew. The stepped skew portion 44 is a skew portion, which refers to a portion that is offset in a step-like manner in the circumferential direction X relative to the second reference portion 43 and is arranged in the axial direction Z. The stepped skew portion 44 is offset in a step-like manner (one level) in the rotational direction X1 in the circumferential direction X relative to the second reference portion 43 and is arranged in the axial direction Z. In this way, the reference portion includes a first reference portion 41 and a second reference portion 43, and the skew portion includes a continuous skew portion 42 and a stepped skew portion 44. In addition, the reference position P_ref of the stator 3 (the reference position of the first reference portion 41) is consistent with the reference position P_ref of the rotor 2 (the reference position of the second reference portion 43).

[0189] The skew at the stepped skew portion 44 relative to the second reference portion 43 is set to half the maximum skew at the continuously skewed portion 42 relative to the first reference portion 41. As described above, in this embodiment, the maximum skew at the continuously skewed portion 42 of the stator 3 relative to the first reference portion 41 is set to half the slot pitch. Therefore, the skew at the stepped skew portion 44 of the rotor 2 relative to the second reference portion 43 is set to one-quarter the slot pitch. Consequently, the relative skew between the stator 3 and rotor 2 is greatest at the other end in the axial direction Z of the stator 3 and rotor 2. The maximum relative skew between the stator 3 and rotor 2 is converted to one slot pitch of the stator core 31 using the continuous skew.

[0190] Figure 32The figure shows a method for converting the skew between the continuous skew portion 42 and the stepped skew portion 44. The continuously skew portion 42 of the stator 3 is gradually offset in the axial direction Z relative to the first reference portion 41 in the counter-rotational direction X2 in the circumferential direction X. The maximum skew relative to the first reference portion 41 is set to 1 / 2 the slot pitch. As shown in the figure, the center position 54a of the continuous skew in the first continuously skew portion 42a (corresponding to the second reference portion 43 of the stepped skew) corresponds to a position shifted by 1 / 8 the slot pitch from the reference position P_ref in the rotational direction X1 in the circumferential direction X. Furthermore, the center position 54b of the continuous skew in the second continuously skew portion 42b (corresponding to the stepped skew portion 44 of the stepped skew) corresponds to a position shifted by 3 / 8 the slot pitch from the reference position P_ref in the rotational direction X1 in the circumferential direction X.

[0191] The difference (1 / 4 of the groove pitch) between the center position 54a of the first continuously skewed portion 42a and the center position 54b of the second continuously skewed portion 42b represents the amount of skew in the step-skewed portion 44 relative to the second reference portion 43. Furthermore, if the center position 54a of the first continuously skewed portion 42a is shifted in the counter-rotational direction X2 in the circumferential direction X by 1 / 8 of the groove pitch, it coincides with the reference position P_ref. Furthermore, if the center position 54b of the second continuously skewed portion 42b is shifted in the counter-rotational direction X2 in the circumferential direction X by 1 / 8 of the groove pitch, it coincides with the center position of the continuously skewed portion 42.

[0192] According to the motor M of this embodiment, the stator 3 includes a first reference portion 41 and a continuously skewed portion 42, while the rotor 2 includes a second reference portion 43 and a stepped skewed portion 44. Furthermore, the skew of the stepped skewed portion 44 relative to the second reference portion 43 is set to half the maximum skew of the continuously skewed portion 42 relative to the first reference portion 41 (in this embodiment, ¼ the slot pitch). This reduces the complexity associated with manufacturing the stator 3 and rotor 2, improving workability during the manufacturing process. Specifically, considering the workability of assembling the windings into the multiple slots 32 of the stator core 31, it is preferable for the stator 3 to have the continuously skewed portion 42 rather than the stepped skewed portion 44. On the other hand, if the permanent magnets 22 are sintered magnets, considering the workability of attaching the permanent magnets 22 to the magnet housing of the rotor core 21, it is preferable for the rotor 2 to have the stepped skewed portion 44 rather than the continuously skewed portion 42. With the above-described configuration, workability in the manufacturing process can be improved in both the stator 3 and the rotor 2 .

[0193] Alternatively, the continuously skewed portion 42 of the stator 3 can be gradually offset relative to the first reference portion 41 in the rotational direction X1 in the circumferential direction X and disposed in the axial direction Z. In this case, the stepped skewed portion 44 of the rotor 2 is preferably offset in a stepwise manner (one level) relative to the second reference portion 43 in the counter-rotational direction X2 in the circumferential direction X and disposed in the axial direction Z. Specifically, when the continuously skewed portion 42 of the stator 3 is offset relative to the first reference portion 41 in the rotational direction X1 in the circumferential direction X, the stepped skewed portion 44 of the rotor 2 is preferably offset relative to the second reference portion 43 in the counter-rotational direction X2 in the circumferential direction X. This achieves the same effects as those described in the second modified embodiment.

[0194] In addition, the stepped deflection portion 44 can also be offset in a stepped manner (multi-step) in the circumferential direction X relative to the second reference portion 43 and arranged in the axial direction Z. In this case, Figure 32 The same as the case of the first level shown, the center positions of the continuous deflection can be made consistent with the center positions of the step deflection, and the deflection amounts relative to the second reference portion 43 in each stage of the step deflection portion 44 can be converted.

[0195] As described above, by providing three basic phase belt sets 51, 52, and 53, each offset by a predetermined number of slots, and optimizing the ratios of m1, m2, and m3, noise and vibration of the motor M caused by low-order excitation forces generated by the winding distribution can be reduced in a fractional-slot motor M. Furthermore, torque ripple caused by the winding distribution can be reduced in an integer-slot motor M. Furthermore, by setting the maximum skew of the continuous skew portion 42 relative to the reference portion 41 so that the maximum value of the relative skew between the stator 3 and rotor 2 is equivalent to the pitch of one slot of the stator core 31, noise and vibration of the motor M caused by high-order excitation forces due to degradation of the circumferential magnetic periodicity reflecting the opposing state of the stator core 31 and rotor core 21 can be reduced. Furthermore, torque ripple and harmonic components contained in the output waveform can be reduced along with the reduction in noise and vibration of the motor M. That is, by optimizing the winding structure and the opposing state of the stator core 31 and the rotor core 21 , it is possible to reduce noise, vibration, and torque ripple in all rotation orders.

[0196] The effects of skew and winding structure optimization vary, or their contribution to noise reduction varies, depending on the magnetic saturation state, shape, and size of the stator core 31 and rotor core 21. However, the combined use of skew and winding structure optimization does not change the ability to reduce noise and vibration across the entire rotation range of the motor M compared to implementing either method alone. On the other hand, the combined use of skew and winding structure optimization results in increased torque loss compared to implementing either method alone. Therefore, if, for example, noise and vibration generated within the operating range of the motor M can be addressed by either skew or winding structure optimization alone, and if noise and vibration reduction alone is sufficient, then only effective countermeasures may be implemented.

[0197] The motor M in the above-described embodiment is not limited to a three-phase AC synchronous motor, and may be an AC motor with any number of phases, an induction motor, a synchronous motor, or the like.

[0198] Industrial applicability

[0199] The present invention can be used in a rotating electric machine including a stator having a plurality of slots for accommodating coils made of conductive wires, and a rotor facing the stator and having a plurality of magnetic poles.

Claims

1. A rotating electrical machine comprising: a stator having a plurality of slots for accommodating coils composed of conductive wires; and a rotor, which is opposed to the stator and has a plurality of magnetic poles, The rotating electrical machine is a fractional slot structure in which the number of slots per pole per phase obtained by dividing the number of slots of the stator by the number of phases and the number of magnetic poles of the rotor is expressed as a simplest fraction with a denominator of 2, or an integer slot structure in which the number of slots per pole per phase is a natural number. The set of coil sides of the coils with the same phase and the same current direction in each pole of the rotor and housed in one or a plurality of adjacent slots is set as a basic phase belt, and a hybrid phase belt group is formed by sequentially stacking the first basic phase belt group, the second basic phase belt group, and the third basic phase belt group in the radial direction of the slot. The first basic phase belt group is formed by arranging the basic phase belts for each pole, the second basic phase belt group is formed by shifting the first basic phase belt group by a predetermined number of slots in the rotation direction of the rotor, and the third basic phase belt group is formed by shifting the second basic phase belt group by the predetermined number of slots in the rotation direction. The magnitudes of the magnetic forces of the phases in each pole of the mixed phase band group are balanced respectively. When the radial number of layers of the first basic phase band group is set to m1, the radial number of layers of the second basic phase band group is set to m2, and the radial number of layers of the third basic phase band group is set to m3, the relationship 0<2×m2 / (m1+m3) is satisfied.

2. The rotating electrical machine according to claim 1, wherein The relationship of 1≤2×m2 / (m1+m3)≤4 is satisfied.

3. The rotating electrical machine according to claim 2, wherein: Satisfies the relationship m1=m3.

4. The rotating electrical machine according to any one of claims 1 to 3, wherein: The predetermined number of slots is the nearest integer to the number of slots per pole obtained by multiplying the number of slots per pole per phase by the number of phases in the case of the fractional slot structure, and is 1 in the case of the integer slot structure.

5. The rotating electrical machine according to any one of claims 1 to 3, wherein: At least one of the stator and the rotor includes: a reference portion that serves as a reference for the deflection; and a skewed portion arranged in a direction orthogonal to the rotational direction and the radial direction while being offset in the rotational direction relative to the reference portion; The skewed portion is set to have a maximum skew amount relative to the reference portion so that the maximum skew amount between the stator and the rotor is converted to a size of one slot pitch of the stator core by continuous skew.

6. The rotating electrical machine according to claim 4, wherein At least one of the stator and the rotor includes: a reference portion that serves as a reference for the deflection; and a skewed portion arranged in a direction orthogonal to the rotational direction and the radial direction while being offset in the rotational direction relative to the reference portion; The skewed portion is set to have a maximum skew amount relative to the reference portion so that the maximum skew amount between the stator and the rotor is converted to a size of one slot pitch of the stator core by continuous skew.

Images