Segmented special-shaped tooth rotor structure of alternating current excitation motor with low-harmonic non-overlapping windings

Abstract

The invention belongs to the technical field of motors, and provides a low-harmonic non-overlapping winding AC excitation motor segmented special-shaped tooth rotor structure, which comprises a rotor core, the rotor core comprises a plurality of coaxially arranged iron core segments, and the surfaces of the plurality of iron core segments are circumferentially provided with a plurality of first-stage rotor slots and a plurality of second-stage rotor slots. The plurality of primary rotor slots and the plurality of secondary rotor slots are distributed at intervals, each primary rotor slot comprises two groups of small slots, each secondary rotor slot comprises two groups of large slots, the plurality of small slots are axially communicated between two adjacent iron core sections, the plurality of large slots are axially communicated between the two adjacent iron core sections, and the cross section shapes of the small slots and the large slots between the two adjacent iron core sections are different; and the alternating-current exciting winding comprises outer layer windings wound among the plurality of small grooves and inner layer windings wound among the plurality of large grooves, and the outer layer winding in one small groove and the inner layer winding in one large groove are arranged in an upper layer and a lower layer in the radial direction. According to the rotor structure, the torque ripple of the motor and the total harmonic distortion of the output voltage can be obviously reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electric machines, and particularly relates to a segmented special-shaped tooth rotor structure of an AC excitation motor with low-harmonic non-overlapping windings. BACKGROUND

[0002] Traditional AC excitation motor rotor windings adopt a distributed winding structure, and there is a problem of difficulty in fixing the end part. Large motor design has a high challenge. The non-overlapping winding structure based on fractional-slot concentrated winding shortens the winding end part and simplifies the fixing structure of the winding. However, the fractional-slot concentrated winding structure produces too high a harmonic content of air gap flux density, which cannot meet the requirements of the power system. Since a large AC excitation motor adopts a wire bar structure, the structure of slant slot cannot be adopted, resulting in large motor torque ripple and total harmonic distortion (THD) of output voltage. SUMMARY

[0003] The application aims to provide a segmented special-shaped tooth rotor structure of an AC excitation motor with low-harmonic non-overlapping windings to solve the above problems and reduce motor torque ripple and output voltage THD.

[0004] To achieve the above-mentioned purpose, the application provides the following scheme: a segmented special-shaped tooth rotor structure of an AC excitation motor with low-harmonic non-overlapping windings, comprising:

[0005] A rotor core comprises a plurality of coaxially arranged core segments. A plurality of first-level rotor slots and a plurality of second-level rotor slots are circumferentially arranged on the surfaces of the core segments. The first-level rotor slots and the second-level rotor slots are distributed at intervals. The first-level rotor slots comprise two groups of small slots, and the second-level rotor slots comprise two groups of large slots. The small slots of two adjacent core segments are axially connected, and the large slots of two adjacent core segments are axially connected. The cross-sectional shapes of the small slots and the large slots of two adjacent core segments are different.

[0006] An AC excitation winding comprises an outer winding wound in the small slots and an inner winding wound in the large slots. The outer winding in the small slot and the inner winding in the large slot are arranged in two layers along the radial direction.

[0007] Preferably, the two layers of windings in any small slot are oppositely wound.

[0008] The two layers of windings in any large slot are oppositely wound.

[0009] Preferably, the two layers of windings in any small slot are oppositely wound.

[0010] The two layers of windings in any large slot are oppositely wound.

[0011] Preferably, the cross-sectional area of the small slots along the axial direction between two adjacent core segments is the same, and the cross-sectional area of the large slots along the axial direction is the same.

[0012] Preferably, the tooth shoulder part of the rotor tooth of the rotor core adopts a stepped structure, and the width of each step from the inner diameter to the outer diameter is 1.2 times the width of the previous step.

[0013] Preferably, the rotor core is circumferentially divided into a first core segment, a second core segment, a third core segment, a fourth core segment and a fifth core segment.

[0014] In the first core segment, the tooth shoulder part of the large tooth between the two small slots adopts a three-step structure, the two end small teeth are two-step structures, the tooth shoulder between the two large slots adopts a four-step structure, and the two ends are two-step structures.

[0015] Preferably, in the second core segment, the left side of the large tooth between the two small slots adopts a two-step structure, and the right side adopts a three-step structure, the left side of the tooth shoulder between the two large slots adopts a three-step structure, and the right side adopts a four-step structure.

[0016] Preferably, in the third core segment, the number of steps on both sides of the small slots and the large slots is the same, the tooth width between two adjacent large slots is l1, the tooth width between adjacent small slots and large slots is l2, and l1 / l2=2π / 3 / Qr / m / p.

[0017] Wherein, Qr is the number of rotor slots, m is the number of phases, and p is the number of pole pairs.

[0018] Preferably, in the fourth core segment, the left side of the large tooth between the two small slots adopts a three-step structure, and the right side adopts a two-step structure, the left side of the tooth shoulder between the two large slots adopts a four-step structure, and the right side adopts a three-step structure.

[0019] Preferably, in the fifth core segment, the tooth shoulder part of the large tooth between the two small slots adopts a two-step structure, the two end small teeth are three-step structures, the tooth shoulder between the two large slots adopts a two-step structure, and the two ends are four-step structures.

[0020] Compared with the prior art, the present application has the following advantages and technical effects: In the present application, by setting a plurality of core segments and making the cross-sectional area of the small slots and the large slots between adjacent core segments different, a segmented special-shaped tooth structure is formed, and by adopting a non-overlapping winding and a segmented special-shaped tooth rotor structure, the purpose of reducing motor torque ripple and output voltage THD can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments will be briefly introduced. Obviously, the accompanying drawings in the following description only only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative labor.

[0022] Figure 1 The schematic diagram of the connection between the windings of the present application;

[0023] Figure 2 The schematic diagram of the whole rotor and matched stator of the present application;

[0024] Figure 3 The schematic diagram of the first core segment of the present application;

[0025] Figure 4 The schematic diagram of the second core segment of the present application;

[0026] Figure 5 The schematic diagram of the third core segment of the present application;

[0027] Figure 6 The schematic diagram of the fourth core segment of the present application;

[0028] Figure 7 The schematic diagram of the fifth core segment of the present application;

[0029] Figure 8 The schematic diagram of the stepped structure of the tooth shoulder of the rotor of the present application;

[0030] Figure 9 The comparison diagram of the torque waveform of the fractional-slot concentrated winding;

[0031] Figure 10 The schematic diagram of the torque waveform output when the rotor structure of the present application runs;

[0032] Figure 11 The schematic diagram of the voltage waveform output when the rotor structure of the present application runs;

[0033] Figure 12 The schematic diagram of the current waveform output when the rotor structure of the present application runs;

[0034] Wherein, 1, small slot; 2, large slot. DETAILED DESCRIPTION

[0035] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0036] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0037] With reference to Figures 1-12 , the present application provides a segmented special-shaped tooth rotor structure of an AC excitation motor with low harmonic non-overlapping windings, comprising:

[0038] A rotor core, the rotor core comprises a plurality of core segments arranged coaxially, a plurality of first rotor slots and a plurality of second rotor slots are circumferentially arranged on the surfaces of the plurality of core segments, the plurality of first rotor slots and the plurality of second rotor slots are distributed at intervals, each first rotor slot comprises two groups of small slots 1, each second rotor slot comprises two groups of large slots 2, the small slots 1 of two adjacent core segments are axially communicated, the large slots 2 of two adjacent core segments are axially communicated, and the cross-sectional shapes of the small slots 1 and the large slots 2 of two adjacent core segments are different.

[0039] An AC excitation winding, comprising an outer layer winding wound between the plurality of small slots 1 and an inner layer winding wound between the plurality of large slots 2, the outer layer winding in one small slot 1 and the inner layer winding in one large slot 2 are both arranged in two layers along the radial direction.

[0040] In the present application, a plurality of core segments are arranged, and the cross-sectional areas of the small slots and the large slots between adjacent core segments are different, thereby forming a segmented special-shaped tooth structure. By adopting the non-overlapping winding and the segmented special-shaped tooth rotor structure, the purposes of reducing motor torque ripple and output voltage THD can be achieved.

[0041] In a further optimization scheme, the two layers of windings in any small slot 1 are reversely wound.

[0042] The two layers of windings in any large slot 2 are reversely wound.

[0043] In a further optimization scheme, between the windings in two adjacent small slots 1, the two adjacent windings in the same layer are reversely wound.

[0044] Between the windings in two adjacent large slots 2, the two adjacent windings in the same layer are reversely wound.

[0045] In the present embodiment, as shown in Figure 1 , the small slots 1 and the large slots 2 are both 12-slot structures, and the number of slots in each phase is 2, which are used to place the upper and lower two layers of windings.

[0046] The concentric non-overlapping structure with a slot number of 2 (i.e., q = 2) can ensure that the rotor winding directly adopts the tooth winding structure, and there is no winding overlap problem in the radial direction. The concentric structure is an outer layer covering an inner layer structure in the axial direction, and the winding end part remains a short structure, which greatly shortens the rotor winding end part compared with the distributed winding, thereby improving the reliability. Compared with the fractional slot concentrated winding (q = 1), the structure makes the winding distribution more uniform through the multi-slot structure, and significantly reduces the 5 / 7 order magnetic potential tooth harmonic of the rotor magnetic field. At the same time, cooperating with the iron core segments (i.e., the circumferential segmentation structure) arranged on the same axis in the rotor, the phase difference of each segment harmonic is generated, and the mutual offset is realized.

[0047] In the 12 groups of small slots 1, A winding and B winding are divided, A winding includes A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, and B winding includes B1, B2, B3, B4, B5, B6, B7, B8, B9, B10, B11, B12. Specifically, the coils are connected in the order of -A11-A2-A1-A12-, -A3-A6-A5-A4-, -A7-A10-A9-A8-, -B1-B4-B3-B2-, -B5-B8-B7-B6-, -B9-B12-B11-B10-.

[0048] Similarly, in the 12 groups of large slots 2, C winding and D winding are divided, C winding includes C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, and D winding includes D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, D12. Specifically, the coils are connected in the order of -C1-C4-C3-C2-, -C5-C8-C7-C6-, -C9-C12-C11-C10-, -D11-D2-D1-D12-, -D3-D6-D5-D4-, -D7-D10-D9-D8-.

[0049] Further optimization scheme, the cross-sectional area of the plurality of small slots 1 between two adjacent iron core segments is the same along the axial direction, and the cross-sectional area of the plurality of large slots 2 along the axial direction is the same.

[0050] Further optimization scheme, the tooth shoulder part of the rotor tooth of the rotor core adopts a stepped structure, and the width of each step from the inner diameter to the outer diameter is 1.2 times the width of the previous step.

[0051] Specifically, as shown in FIG. 8, K3 / K2 = K2 / K1 = 1.2. Figure 8

[0052] Further optimization scheme, the rotor core is circumferentially divided into a first iron core segment, a second iron core segment, a third iron core segment, a fourth iron core segment, and a fifth iron core segment. ​

[0053] As Figure 3 shown, in the first core segment, the tooth shoulder part of the large tooth between the two small slots 1 adopts a three-step structure, the two end small teeth are two-step structure, the tooth shoulder between the two large slots 2 adopts a four-step structure, and the two ends are two-step structure.

[0054] Further optimization scheme, as Figure 4 shown, in the second core segment, the left side of the large tooth between the two small slots 1 adopts a two-step structure, and the right side adopts a three-step structure, the left side of the tooth shoulder between the two large slots 2 adopts a three-step structure, and the right side adopts a four-step structure.

[0055] Further optimization scheme, as Figure 5 shown, in the third core segment, the same number of steps is adopted on both sides of the small slot 1 and the large slot 2, the tooth width between the two adjacent large slots 2 is l1, the tooth width between the adjacent small slot 1 and the large slot 2 is l2, and l1 / l2=2π / 3 / Qr / m / p,

[0056] wherein Qr is the number of rotor slots, m is the number of phases, and p is the number of pole pairs.

[0057] Further optimization scheme, as Figure 6 shown, in the fourth core segment, the left side of the large tooth between the two small slots 1 adopts a three-step structure, and the right side adopts a two-step structure, the left side of the tooth shoulder between the two large slots 2 adopts a four-step structure, and the right side adopts a three-step structure.

[0058] Further optimization scheme, as Figure 7 shown, in the fifth core segment, the tooth shoulder part of the large tooth between the two small slots 1 adopts a two-step structure, the two end small teeth are three-step structure, the tooth shoulder between the two large slots 2 adopts a two-step structure, and the two ends are four-step structure.

[0059] The special-shaped stepped structure increases the space in the slot, increases the magnetic resistance in the slot, and suppresses the leakage magnetic flux in the slot.

[0060] As Figures 9-12 shown, compared with the torque waveform output by the fractional slot concentrated winding form, the improved rotor structure in the embodiment has obvious improvement in torque ripple. Moreover, the improved voltage output and current output are more stable and do not have obvious distortion.

[0061] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0062] The above-described embodiments are merely intended to describe the preferred modes of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements of the present application made by those skilled in the art based on the above-described embodiments should fall within the scope of the present application defined by the claims.

Claims

1. A fractional-slot skewed tooth rotor structure for an AC excited electric machine with low harmonic non-overlapping windings, characterized in that, The rotor core comprises a plurality of coaxially arranged core segments, a plurality of first rotor slots and a plurality of second rotor slots are arranged on the surface of the core segments in a circumferential direction, the first rotor slots and the second rotor slots are distributed at intervals, the first rotor slots comprise two groups of small slots (1), the second rotor slots comprise two groups of large slots (2), the small slots (1) between two adjacent core segments are axially connected, the large slots (2) between two adjacent core segments are axially connected, and the cross-sectional shapes of the small slots (1) and the large slots (2) between two adjacent core segments are different; The AC excitation winding comprises an outer layer winding wound between the small slots (1) and an inner layer winding wound between the large slots (2), and the outer layer winding in one small slot (1) and the inner layer winding in one large slot (2) are arranged in two layers in a radial direction. The two layers of windings in any small slot (1) are oppositely wound; 2. The low harmonic non-overlapping winding AC-excited electric machine segmented canted tooth rotor structure of claim 1, wherein: The two layers of windings in any large slot (2) are oppositely wound. The two adjacent windings in the same layer in the two adjacent small slots (1) are oppositely wound; 3. The low harmonic non-overlapping winding AC-excited electric machine segmented canted tooth rotor structure of claim 1, wherein: The two adjacent windings in the same layer in the two adjacent large slots (2) are oppositely wound. The cross-sectional areas of the small slots (1) between two adjacent core segments in an axial direction are the same, and the cross-sectional areas of the large slots (2) between two adjacent core segments in an axial direction are the same.

4. The low harmonic non-overlapping winding AC-excited electric motor segmented cored- bar rotor structure of claim 1, wherein: The tooth shoulder part of the rotor tooth of the rotor core adopts a stepped structure, and the width of each step from the inner diameter to the outer diameter is 1.2 times the width of the previous step.

5. The low harmonic non-overlapping winding AC-excited electric machine segmented canted tooth rotor structure of claim 1, wherein: The rotor core is divided into a first core segment, a second core segment, a third core segment, a fourth core segment and a fifth core segment in a circumferential direction.

6. The low harmonic non-overlapping winding AC-excited electric machine segmented canted tooth rotor structure of claim 1 wherein: In the first core segment, the tooth shoulder part of the large tooth between two small slots (1) adopts a three-step structure, the small tooth at both ends adopts a two-step structure, the tooth shoulder between two large slots (2) adopts a four-step structure, and the tooth shoulder at both ends adopts a two-step structure. In the second core segment, the left side of the large tooth between two small slots (1) adopts a two-step structure, the right side adopts a three-step structure, the left side of the tooth shoulder between two large slots (2) adopts a three-step structure, and the right side adopts a four-step structure.

7. The low harmonic non-overlapping winding AC-excited electric motor segmented cored- bar rotor structure of claim 6, wherein: In the third core segment, the same number of steps are adopted on both sides of the small slots (1) and the large slots (2), the tooth width between two adjacent large slots (1) is l1, the tooth width between adjacent small slots (1) and large slots (2) is l2, and l1 / l2 = 2π / 3 / Qr / m / p, 8. The low harmonic non-overlapping winding AC-excited electric motor segmented cored- bar rotor structure of claim 6, wherein: wherein Qr is the number of rotor slots, m is the number of phases, and p is the number of pole pairs. In the fourth core segment, the left side of the large tooth between two small slots (1) adopts a three-step structure, the right side adopts a two-step structure, the left side of the tooth shoulder between two large slots (2) adopts a four-step structure, and the right side adopts a three-step structure.

9. The low harmonic non-overlapping winding AC-excited electric motor segmented cored- bar rotor structure of claim 6, wherein: In the fifth core segment, the tooth shoulder part of the large tooth between two small slots (1) adopts a two-step structure, the small tooth at both ends adopts a three-step structure, the tooth shoulder between two large slots (2) adopts a two-step structure, and the tooth shoulder at both ends adopts a four-step structure.

10. The low harmonic non-overlapping winding AC-excited electric motor segmented cored- bar rotor structure of claim 6, wherein: ​

Images