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EP-4742501-A1 - STATOR STRUCTURE WITH FLAT WIRE WINDINGS

EP4742501A1EP 4742501 A1EP4742501 A1EP 4742501A1EP-4742501-A1

Abstract

A stator structure with flat wire windings comprises a stator core, flat wire windings, and insulation sheets. The stator core includes an annular yoke and multiple arranged circumferentially along the yoke, with slots extending radially between adjacent pairs of teeth, and each pair of teeth having shoes extending circumferentially from the ends thereof to form a slot opening. The flat wire winding consists of a linear conductor with an inserted section positioned within the slot. The insulation sheet is installed in the slot to encase the arranged inserted sections, and the slot contains a pair of protruding blocks that extend in a direction perpendicular to the radial direction, thereby confining the inserted section between the protruding blocks and the slot bottom.

Inventors

  • CHANG, CHING-FENG
  • CHU, CHIH-MENG
  • WU, ZHI-ZHENG
  • CHANG, CHEN-HUI

Assignees

  • Fukuta Electric & Machinery Co., Ltd.

Dates

Publication Date
20260513
Application Date
20241110

Claims (8)

  1. A stator structure with flat wire windings, comprising: a stator core (10) including an yoke (11) in an annular form and multiple teeth (12) arranged circumferentially along the yoke (11), with slots (15) extending radially between adjacent pairs of teeth (12), each pair of teeth (12) having shoes (121) extending circumferentially from the ends thereof to form a slot opening (151); flat wire windings (30) comprising multiple linear conductors (31) with inserted sections (31A) positioned within the slots (15); and insulation sheets (20) encasing the inserted sections (31A) arranged in sequence, and being installed in the slots (15) between the inserted sections (31A) and surfaces of the slots (15); characterized in that , a pair of protruding blocks (14a, 14b) is provided inside each of the slots (15), extending in a direction perpendicular to the radial direction, with the inserted sections (31A) confined between the pair of protruding blocks (14a,14b) and a slot bottom (153) of each of the slots (15); wherein, in the direction perpendicular to the radial direction (Da), a width of the slot is Sw, a width of the slot opening (151) is G1, a width of the inserted section is Lw, a thickness of the insulation sheet is It, and a distance between the pair of protruding blocks (14a, 14b) is G2, satisfying the following conditions: G1 ≤ G2 < Lw , and It + 0.2 mm < 0.5 × Sw − G 2 ≤ It + 1 mm .
  2. The stator structure with flat wire windings according to Claim 1, wherein the following condition is satisfied: 0.1mm ≤ It ≤ 0.3mm.
  3. The stator structure with flat wire windings according to Claims 1 or 2, wherein the following condition is satisfied: It + 0.2 mm < 0.5 × (Sw-G2) ≤ It + 0.6 mm.
  4. The stator structure with flat wire windings according to any one of above Claims, wherein a junction between each of the shoes (121) and each of the protruding blocks (14a,14b) forms a flat section (13).
  5. The stator structure with flat wire windings according to any one of above Claims, wherein each of the insulation sheets (20) comprises a main section (21) and two overlap sections (22A,22B) extending outwardly from opposite sides of the main section (21), with each of the insulation sheets (20) bent such that the two overlap sections (22A,22B) enclose the inserted sections (31A) arranged in sequence and are oriented toward the slot bottom (153).
  6. The stator structure with flat wire windings according to any one of above Claims, wherein each of the protruding blocks (14a,14b) has a tip (14) and two angled surfaces (14s1,14s2) extending from opposite sides of the tip (14), and each of the slots (15) has two slot walls (152) extending from opposite sides of the slot bottom (153); wherein, in a cross-section, extension lines of the two angled surfaces (14s1,14s2) intersect with extension lines of their adjacent slot walls (152) to define a first point (14p1) and a second point (14p2), with the second point (14p2) positioned between the first point (14p1) and each of the shoes (121), and the extension line of each of the slot walls (152) intersect with a boundary of an inner circumferential surface (51) of the stator core (10) and defines a third point (51p3), and wherein, in the cross-section, each of the inserted sections (31A) has a thickness Lt parallel to the extension line of each of slot walls (152), the distance from the first point (14p1) to the second point (14p2) is L3, and the distance from the second point (14p2) to the third point (51p3) is L4, satisfying the condition: Lt ≤ L3 + L4 .
  7. The stator structure with flat wire windings according to Claim 6, wherein the following condition is satisfied: Lt ≤ L4.
  8. The stator structure with flat wire windings according to any one of above Claims, wherein varnish is filled between the insulation sheets (20) and the inserted sections (31A).

Description

FIELD OF INVENTION The present disclosure relates to a stator structure, and more particularly to a stator structure using flat wire windings. BACKGROUND OF THE INVENTION The basic structure of a motor consists of a stator and a rotor, which convert electrical energy into rotational kinetic energy by electromagnetic induction principles to provide torque output. The interaction between the magnetic fields of the stator and the rotating element determines the output performance of the motor. The stator core structure includes an annular yoke and multiple teeth arranged circumferentially along the yoke, with slots extending radially between adjacent pairs of teeth. The ends of each pair of teeth have shoes extending circumferentially to form a slot opening. The function of the shoes is to collect magnetic flux, the greater the circumferential extent of the shoes, the greater the magnetic flux that can be accommodated by the stator core. Consequently, the shoes that form the slot opening are typically narrow and flat in shape, making them relatively fragile in strength. In the stator windings of three-phase induction motors, copper wires known as hairpin windings are commonly used to form the flat wire windings. Compared to the traditional windings with circular wire cross-sections, the flat wire (also called rectangular wire) windings not only increase the slot filling rate and allow higher current carrying capacity, but also provide better heat dissipation characteristics, which are beneficial for motor operation at high power density and high efficiency. When assembling the hairpin windings, multiple flat copper wires are first sequentially bent into hairpin conductors. Then, according to the wiring layout, the multiple hairpin conductors are stacked along the radial direction of stator core and arranged in a ring shape along the circumferential direction of the stator core. The open ends of the conductors are then inserted axially into the slots of the stator core. Finally, the open ends of the hairpins are twisted, levelled, and welded processes to form the flat wire windings. After the formed hairpin conductors are inserted into the stator core, the conductors will still expand radially within the slots due to the material properties of copper combined with the geometric tolerances from the bending and twisting operations. Furthermore, to ensure insulation within the stator core slots, after the flat wire windings are formed, varnish is injected into the slots to fill any gaps and prevent wire movement, thereby avoiding insulation deterioration from magnet wire wear. However, since varnish has the characteristic of volume expansion during curing, this can cause conductor displacement or deformation within the gaps, potentially causing the hairpin conductors near the inner diameter of the core to protrude from the slot openings. If the rotor is installed and operated under such conditions, it may contact the conductors, leading to stator damage and increased product defect rates. SUMMARY OF THE INVENTION The present disclosure provides a stator structure with flat wire windings comprising a stator core, flat wire windings, and insulation sheets. The stator core includes an annular yoke with multiple teeth arranged circumferentially along the yoke. Pairs of adjacent teeth are extending radially, forming slots therebetween, with shoes extending circumferentially from the ends of each pair of teeth to form a slot opening. The flat wire windings consist of multiple linear conductors with inserted sections positioned within the slots. The insulation sheet encases the inserted sections arranged in sequence, and is installed in the slot between the inserted sections and the slot surfaces. A pair of protruding blocks is provided inside the slot, and extends in a direction perpendicular to the radial direction, with the inserted sections confined between the protruding blocks and the slot bottom. In a direction perpendicular to the radial direction, the width of the slot is Sw, the width of the slot opening is G1, the width of the inserted section is Lw, the thickness of the insulation sheet is It, and the distance between the pair of protruding blocks is G2. These parameters satisfy the following conditions: G1≤G2<LwandIt+0.2mm<0.5×Sw−G2≤It+1mm. In this structure, the pair of protruding blocks within the slot confine the multiple linear conductors (flat copper wires) within the slot. Therefore, when the flat copper wires experience deformation from external forces, their deformation is constrained between the protruding blocks and the slot bottom, thereby enhancing manufacturing yield. Additionally, the following condition may also be satisfied: 0.1 mm ≤ It ≤ 0.3 mm. Furthermore, the insulation sheet comprises a main section and two overlap sections extending outwardly from opposite sides of the main section. The insulation sheet is bent to allow the two overlap sections to enclose the inserted sections arranged