A flat wire winding layout structure with a constant cross-sectional area and a high slot fill factor

Abstract

The present invention discloses a concentrated flat wire winding layout structure with equal cross-sectional area and high slot fill factor. The flat wire winding layout structure includes a plurality of flat wire windings and a stator core with non-rectangular stator slots. Each flat wire winding is respectively wound on one stator core tooth portion in the stator core and has the same arrangement. The width of each layer of flat wire in each flat wire winding increases layer by layer from the narrower side to the wider side of the stator slot of the stator core, and the thickness of each layer of flat wire increases layer by layer from the wider side to the narrower side of the stator slot of the stator core. The total cross-sectional area of each layer of flat wire is the same, and the wire ends of each flat wire winding are connected to each other at the motor end. The present invention can effectively improve the slot fill factor of the flat wire winding in the non-rectangular slot, solve the problem of low space utilization rate, and further improve the motor efficiency and power density. At the same time, it ensures that the current density at different positions of the conductor in the slot is basically the same, avoids insulation failure caused by excessive local temperature rise, and can effectively improve the reliability of the winding.

Description

Technical Field

[0001] The present invention relates to a layout structure of a flat wire winding, belonging to the technical field of motors, and particularly to a layout structure of a flat wire winding with a high slot fill factor and an equal cross-sectional area. Background Art

[0002] Flat wire windings have been widely used in electric vehicles and large industrial fields due to their advantages such as high slot fill factor, low winding loss, good thermal conductivity, and low electromagnetic noise. The cross-section of a flat wire winding is rectangular, and when arranged, a relatively tight layout can be achieved, thereby increasing the slot fill factor of the motor and achieving a higher power density. When designing a flat wire motor, a rectangular slot structure is more commonly used. This structure may lead to uneven magnetic flux density distribution in the stator teeth, and the magnetic flux density at the tooth top is significantly larger than that at the tooth root, which may cause local magnetic saturation or waste of space. However, because its cross-section is rectangular, the layout structure of its winding is not as adaptable to different tooth-slot types as that of round wire, and it is extremely easy to cause waste of space when arranged in non-rectangular slots such as pear-shaped slots and trapezoidal slots. Although some documents have proposed a layout structure of a flat wire winding with unequal cross-sectional areas to increase the slot fill factor, due to the change in the cross-sectional area of the conductor, the current density at different positions in the slot will be different, which is likely to cause local temperature rise. At the same time, existing flat wire motors mostly use hairpin windings, and multiple flat wire conductors need to be connected by welding, resulting in a significant increase in the number of solder joints on the winding, increasing the process difficulty and reducing the reliability of the motor. Therefore, it is necessary to study a new winding layout structure to increase the slot fill factor of the flat wire winding in non-rectangular slots, so as to achieve a motor design scheme with high efficiency, high power density, high reliability, and low processing difficulty. Summary of the Invention

[0003] In order to solve the problems existing in the background art, the present invention provides a layout structure of a flat wire winding with a high slot fill factor and an equal cross-sectional area. While increasing the slot fill factor of the flat wire winding in non-rectangular slots, the present invention ensures uniform distribution of the current density of the conductors in the slot, reduces the number of solder joints of the motor, and improves the power density and reliability of the motor.

[0004] The technical solution adopted by the present invention is:

[0005] The layout structure of the concentrated flat wire winding with equal cross-sectional area of the present invention includes a plurality of flat wire windings and a stator core having non-rectangular stator slots. Each flat wire winding is wound around one stator core tooth of the stator core respectively and has the same arrangement. The width of each layer of flat wire of each flat wire winding increases layer by layer from the narrower side to the wider side of the stator slot of the stator core. The thickness of each layer of flat wire of each flat wire winding increases layer by layer from the wider side to the narrower side of the stator slot of the stator core. The total cross-sectional area of each layer of flat wire of each flat wire winding is the same. The wire ends of each flat wire winding are connected to each other by welding or other means at the end of the motor. Each flat wire winding has the same arrangement, that is, the number of winding layers, the width, thickness and arrangement position of the corresponding layer windings of the flat wire windings on each stator core tooth are the same.

[0006] The flat wire winding is a continuous flat wire. The width and thickness dimensions of the continuous flat wire winding wound around the same stator core tooth are not exactly the same at different positions along the wire. The flat wire wound around the stator core tooth for one week and located in the same layer is in the shape of an approximately slender cuboid with uniform width and thickness dimensions. The bending position between every two adjacent layers of flat wire is located at the same side end of the stator core tooth and is in the shape of an approximately trapezoid. The width and thickness of the flat wire gradually change along the wire at the bending position between adjacent layers of flat wire. The size of one end cross-section at the bending position between adjacent layers of flat wire is the same as the cross-section size of one layer of flat wire close to the narrower side of the stator slot of the stator core, and the size of the other end cross-section at the bending position between adjacent layers of flat wire is the same as the cross-section size of one layer of flat wire close to the wider side of the stator slot of the stator core.

[0007] The stator slot of the stator core is a semi-closed slot, specifically a parallel tooth flat bottom slot structure. The bottom edge of the stator slot is perpendicular to the stator tooth body. The stator slot is wider at the position close to the stator core yoke and narrower at the slot opening position far from the stator core yoke. The width of the layer of flat wire closest to the stator core yoke in the flat wire winding is the largest and the thickness is the smallest. The width of several layers of flat wire gradually decreases and the thickness gradually increases from the position close to the stator core yoke to the slot opening position. The width of the layer of flat wire closest to the slot opening of the stator slot is the smallest and the thickness is the largest.

[0008] The flat wire winding is symmetrically distributed in the stator slots on both sides of the stator core tooth along the cross-section perpendicular to the axial direction of the stator core. The total cross-sectional areas of the two symmetric cross-sections of each layer of flat wire of the flat wire winding are the same, while the width and thickness are different. The two symmetric cross-sections of each layer of flat wire are approximately rectangular, with the long side perpendicular to the stator tooth body and parallel to the bottom edge of the stator slot.

[0009] The stator core is a spliced stator, specifically a split tooth structure, a tooth-yoke separation structure or a combination of a split tooth structure and a tooth-yoke separation structure. Each adjacent stator core tooth of the stator core is integrally formed through a plurality of connecting bars.

[0010] When the flat wire winding is processed, a vertical winding method is adopted, and the flat wire winding on a single stator core tooth is formed by a winding machine in one pass.

[0011] A layer of slot insulation layer is coated on the stator slot wall of the stator core.

[0012] A layer of winding insulation paint film is coated on the surface of the flat wire winding.

[0013] The beneficial effects of the present invention are as follows:

[0014] 1) The present invention can improve the slot fill factor of the flat wire winding in a non-rectangular slot in a parallel tooth structure motor, solve the problem of low space utilization rate, combine the advantages of uniform magnetic circuit distribution in parallel teeth and high slot fill factor of the flat wire winding, and can improve the efficiency and power density of the motor.

[0015] 2) The present invention keeps the cross-sectional areas of the conductors in different layers of the flat wire winding the same, avoids the problem of uneven current density distribution in the slot caused by the change of the conductor area, and ensures that the current densities at different positions of the conductors in the slot are basically the same; compared with the existing layout method of flat wire windings with unequal areas, the problem of uneven heat generation positions in the slot can be reduced to a certain extent, and the insulation failure of the winding caused by too high local temperature rise can be avoided.

[0016] 3) The winding on a single stator tooth of the present invention is formed by a winding machine in one pass, effectively reducing the number of solder joints, which can effectively improve the reliability of the winding and reduce the difficulty of welding processing.

[0017] 4) The present invention adopts a spliced stator structure, with relatively low winding difficulty, reducing the risk of copper wire damage during the winding process. At the same time, the limitation of the width of the flat wire winding on the slot opening size caused by winding from the slot opening position is eliminated, and a semi-closed slot can be used to further reduce the torque ripple of the motor. Description of the Drawings

[0018] Figure 1 is a schematic diagram of the stator structure of the high slot fill factor concentrated flat wire winding with equal cross-sectional area in an embodiment of the present invention;

[0019] Figure 2 is a cross-sectional view of the layout structure of the high slot fill factor concentrated flat wire winding with equal cross-sectional area of the present invention;

[0020] Figure 3 is a top view of the stator structure of the flat wire winding in an embodiment of the present invention;

[0021] Figure 4 is a bottom view of the stator structure of the flat wire winding in an embodiment of the present invention;

[0022] Figure 5Schematic diagram of the layout structure of the flat wire winding on a single stator tooth of the present invention;

[0023] Figure 6 Cross-sectional view of the flat wire winding of the present invention on a single stator core tooth;

[0024] Figure 7 Schematic diagram of the straight section of the flat wire winding of the present invention;

[0025] In the figure: 1. Stator core tooth part, 2. Stator core yoke part, 3. Slot insulation layer, 4. Flat wire winding, 5. Winding insulation paint film. Detailed implementation manners

[0026] In order to describe the technical solutions in the embodiments of the invention more clearly and accurately, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] As Figure 1 、 Figure 2 、 Figure 3 and Figure 4 shown, the stator core of the 18-slot concentrated flat wire winding motor adopted in the embodiment of the present invention. The stator of the present invention adopts a tooth-yoke separated structure. During processing, the flat wire winding 4 is first wound on the stator core tooth part 1, and after winding, it is spliced with the stator core yoke part 2 to form a complete stator structure. The stator core is a spliced stator, specifically a split tooth structure, a tooth-yoke separated structure, or a combination of a split tooth structure and a tooth-yoke separated structure. Each adjacent stator core tooth part 1 of the stator core is integrally formed through a plurality of connecting bars. The stator core includes 18 flat wire windings 4 and a stator core with 18 non-rectangular stator slots. Each flat wire winding 4 is respectively wound on one stator core tooth part 1 of the stator core and is arranged in the same way. The width of each layer of flat wire of each flat wire winding 4 increases layer by layer from the narrower side to the wider side of the stator slot of the stator core, and the thickness of each layer of flat wire of each flat wire winding 4 increases layer by layer from the wider side to the narrower side of the stator slot of the stator core. The total cross-sectional area of each layer of flat wire of each flat wire winding 4 is the same; the wire ends of each flat wire winding 4 are connected to each other by welding or other means at the end of the motor. Each flat wire winding 4 is arranged in the same way, that is, the number of winding layers, the width, thickness, and arrangement position of the corresponding layer windings of the flat wire winding 4 on each stator core tooth part 1 are the same.

[0028] The stator slots of the stator core are semi-closed slots, specifically a parallel tooth flat bottom slot structure. The bottom edge of the stator slot is perpendicular to the stator tooth body. The stator slot is wider near the yoke part 2 of the stator core and narrower at the slot opening position far from the yoke part 2 of the stator core. The width of the layer of flat wire closest to the yoke part 2 in the flat wire winding 4 is the largest and the thickness is the smallest. The width of several layers of flat wires gradually decreases and the thickness gradually increases from the position near the yoke part 2 of the stator core to the slot opening position. The width of the layer of flat wire closest to the slot opening of the stator slot is the smallest and the thickness is the largest. A layer of slot insulation layer 3 is coated on the wall of the stator slot of the stator core.

[0029] As Figure 5 shown, the flat wire winding 4 is a continuous flat wire. The width and thickness dimensions of the continuous flat wire winding 4 wound on the same stator core tooth part 1 are not exactly the same at different positions along the line. The flat wire wound around the stator core tooth part 1 for one week and located in the same layer is in the shape of an approximately slender cuboid with uniform width and thickness dimensions. The bending position between every two adjacent layers of flat wires is located at the same side end of the stator core tooth part 1 and is in the shape of an approximately trapezoid. The width and thickness of the flat wire gradually change along the line at the bending position between adjacent layers of flat wires. The size of one end cross-section at the bending position between adjacent layers of flat wires is the same as the cross-section size of the layer of flat wire closer to the narrower side of the stator slot near the stator core, and the size of the other end cross-section at the bending position between adjacent layers of flat wires is the same as the cross-section size of the layer of flat wire closer to the wider side of the stator slot near the stator core. Geometrically, the flat wire winding 4 can be regarded as composed of an approximately slender cuboid with uniform width and thickness dimensions and an approximately trapezoid with gradually increasing width and thickness dimensions arranged alternately.

[0030] The flat wires of the flat wire winding 4 on both sides of the stator core tooth part 1 are symmetric with respect to the tooth body. The width and thickness dimensions of the flat wires in the same layer are the same, and the width and thickness dimensions of the flat wires in different layers are different, but the cross-sectional areas are all kept consistent. Adjust the width and thickness dimensions of the flat wire to make it fill the entire stator slot as much as possible. Since the stator slot is wider near the yoke part 2 of the stator core, the closer the flat wire is to the yoke part 2 of the stator core, the larger the width and the smaller the thickness; the stator slot is narrower near the slot opening position, and the closer to the slot opening, the width of the flat wire gradually decreases and the thickness gradually increases. The width of the flat wire at the position closest to the slot opening is the smallest and the thickness is the largest.

[0031] The flat wire winding 4 is symmetrically distributed in the stator slots on both sides of the stator core tooth part 1 along the cross-section perpendicular to the axial direction of the stator core. The total areas of the two symmetric cross-sections of each layer of flat wire in the flat wire winding 4 are the same, but the width and thickness are different. The two symmetric cross-sections of each layer of flat wire are approximately rectangular, with the long side perpendicular to the stator tooth body and parallel to the bottom edge of the stator slot. The flat wire winding 4 is wound in a vertical winding method during processing, and the flat wire winding 4 on a single stator core tooth part 1 is formed by one-time winding by a winding machine. A layer of winding insulation paint film 5 is coated on the surface of the flat wire winding 4.

[0032] As Figure 5 , Figure 6 and Figure 7 shown, in the embodiment of the present invention, the number of layers of the flat wire winding 4 in the stator slot is selected as 8 layers, the thickness of the slot insulation layer 3 is 0.3 mm, and the thickness of the winding insulation paint film 5 of the flat wire winding 4 is 0.1 mm. A right trapezoidal area available for arranging the flat wire winding 4 is intercepted along the cross-section of the stator slot. Suppose the length of its upper base is D1, the length of its lower base is D2, the height is H, and the thickness of the winding insulation paint film 5 is set as d. Select the layer of flat wire closest to the slot opening as the first layer of flat wire. Suppose its thickness is h1, width is w1, and cross-sectional area is S Δ . Starting from the first layer of flat wire and moving towards the direction close to the stator core yoke 2, by the same token, the second to nth layer windings are respectively. The thickness of the ith layer winding is h i , width is w i , and cross-sectional area is S Δ . Then the following formula is satisfied:

[0033]

[0034] h1*w1 = h i *w i = S Δ

[0035] When designing the arrangement of the flat wire winding 4, for the sake of simplifying the calculation, after reserving the thickness of the winding insulation paint film 5 at the short side positions on both sides, make the two short sides of the flat wire cross-section as close as possible to the edge of the trapezoidal available arrangement area. Only at the long side of the flat wire in the trapezoid, the thickness of the winding insulation paint film 5 is 0.1 mm, that is, there is a 0.2 mm winding insulation paint film 5 between two adjacent layers of flat wire. Thus, by means of geometric relationships, the following relational formula between width and thickness can be obtained:

[0036]

[0037] After joint solution, the thickness of the first layer of flat wire in this embodiment is 2.46 mm, the width is 5.12 mm, and the cross-sectional area of each layer of flat wire is 12.63 mm 2 , and the slot fill factor reaches 73.22%.

[0038] The flat wire winding 4 on a single stator core tooth 1 is wound by a continuous flat wire, and the width and thickness of the flat wire at different positions along the wire are not completely the same. The first layer of flat wire is wound starting from the first layer of flat wire near the slot position, corresponding to the first layer of flat wire segments on both sides of the stator core tooth 1, the width and thickness remain uniform, and the first layer of flat wire is wound around the stator core tooth 1 for one round, and then the width of the flat wire at the end gradually increases, and the thickness gradually decreases. When the end of the second layer is wound and connected to the corner of the slot position, the width and thickness change to the same as the width and thickness of the second layer of flat wire calculated above, and the subsequent flat wire change trend is similar.

[0039] By changing the position of the mold when processing the flat wire used for winding, the flat wire with the above-mentioned regular changes is processed. When winding, it is necessary to ensure that the layer-changing section of the flat wire winding 4 is located at the end of the motor, and the flat wires in the stator slots are all regular rectangular sections with constant width and thickness. Therefore, it is necessary to plan the required length of each layer of flat wire and the length of the layer-changing section at the end of the winding according to the winding path adopted.

[0040] The flat wire winding 4 in the embodiment of the present invention is a continuous flat wire on a single stator core tooth 1, which is wound once by a winding machine in a vertical winding manner. The outlet and inlet ends of the flat wire winding 4 extend from the end of the stator, and the bridge wire and lead wire can be arranged according to the actual needs of the motor, and a complete flat wire concentrated winding is formed by welding.

[0041] The concentrated flat wire winding layout structure of equal cross-sectional area of the present invention can realize the close arrangement of the flat wire winding 4 in the non-rectangular slot while ensuring the uniform distribution of current density at various locations in the stator slot, effectively improve the slot fill rate of the flat wire winding 4 in the non-rectangular slot, and help to improve the reliability and power density of the flat wire motor.

Claims

1. A concentrated flat wire winding layout structure with an equal cross-sectional area and a high slot fill factor, characterized in that: It includes a number of flat wire windings (4) and a stator core with non-rectangular stator slots. Each flat wire winding (4) is respectively wound around one stator core tooth portion (1) in the stator core and has the same arrangement. The width of each layer of flat wire in each flat wire winding (4) increases layer by layer from the narrower side to the wider side of the stator slot of the stator core, and the thickness of each layer of flat wire in each flat wire winding (4) increases layer by layer from the wider side to the narrower side of the stator slot of the stator core. The total cross-sectional area of each layer of flat wire in each flat wire winding (4) is the same; The flat wire winding (4) is a continuous flat wire with a width and thickness that vary along the winding path but a constant cross-sectional area on a single stator tooth. The flat wire in one layer of the flat wire winding (4) wound around the stator core tooth portion (1) for one week is in the shape of a cuboid with uniform width and thickness dimensions. The bending position between every two adjacent layers of flat wire is located at the same side end of the stator core tooth portion (1) and is in the shape of a trapezoid. The size of one end cross-section at the bending position between adjacent layers of flat wire is the same as the cross-sectional size of the layer of flat wire close to the narrower side of the stator slot of the stator core, and the size of the other end cross-section at the bending position between adjacent layers of flat wire is the same as the cross-sectional size of the layer of flat wire close to the wider side of the stator slot of the stator core; The structure of the flat wire winding (4) is for a split stator core, specifically a stator with a segmented tooth structure, a tooth-yoke separation structure, or a combination of a segmented tooth structure and a tooth-yoke separation structure. The flat wire winding (4) is formed by one-time winding and then installed into the stator teeth, and then the stator core is assembled by splicing.

2. The layout structure of the concentrated flat wire winding with equal cross-sectional area and high slot fill factor according to claim 1, characterized in that: The design method of each of the flat wire windings (4) includes the following steps: First step, determine the number of layers of the flat wire winding (4), the thickness of the slot insulation layer, and the thickness parameter of the winding insulation paint film; Second step, cut out a right trapezoidal area for the arrangement of the flat wire winding (4) along the stator slot cross-section. The upper base length of the right trapezoidal area is D1, the lower base length is D2, the height is H, and the thickness of the winding insulation paint film (5) is d; Third step, select the layer of flat wire closest to the slot opening position in the flat wire winding (4) as the first layer of flat wire. The thickness of the first layer of flat wire is h1, the width is w1, and the cross-sectional area is S Δ ; Starting from the first layer of flat wire and moving towards the direction close to the stator core yoke (2), the subsequent layers are the second to nth windings. The thickness of the ith winding is h i , the width is w i , and the cross-sectional area is S Δ , then the following formula is satisfied: h1 * w1 = h i * w i = S Δ When designing the arrangement of the flat wire winding (4), after reserving the thickness of the winding insulation paint film (5) at the two short side positions, the two short sides of the flat wire cross-section are made to be close to the edges of the drawn right trapezoidal area. Thus, the relationship between the width and thickness is obtained as follows: After solving the above three formulas simultaneously, the thickness and width of the first layer of flat wire and the cross-sectional area of each layer of flat wire are obtained, and then the specific thickness and width of the remaining layers of flat wire are obtained by recursion, so as to determine the optimal parameter combination of the flat wire winding (4). The layout structure of the concentrated flat wire winding with equal cross-sectional area of the present invention, through the optimal parameter combination of the flat wire winding (4) determined by the above design method, can achieve the close arrangement of the flat wire winding (4) in the non-rectangular slot on the premise of ensuring uniform distribution of the current density at each part in the stator slot, effectively improve the slot fill factor of the flat wire winding (4) in the non-rectangular slot, and contribute to improving the reliability and power density of the flat wire motor.

3. The layout structure of the concentrated flat wire winding with equal cross-sectional area and high slot fill factor according to claim 1, characterized in that: The winding process of each flat wire winding (4) is as follows. The flat wire winding (4) on a single stator core tooth portion (1) is wound by a continuous flat wire, and the width and thickness dimensions of the flat wire at different positions along the wire are not exactly the same. Starting from the first layer of flat wire near the slot opening, for the first layer of flat wire segments on both sides of the stator core tooth portion (1), the width and thickness remain uniform and unchanged. After winding around the stator core tooth portion (1) for one week to complete the winding of the first layer of flat wire, the width of the flat wire at the end gradually increases and the thickness gradually decreases. When reaching the corner connection between the end of the second layer and the position in the slot, the width and thickness change to the same width and thickness dimensions as those of the second layer of flat wire. The winding processes of the subsequent layers of flat wire are the same; By changing the position of the die during the processing of the flat wire used for winding, a flat wire with regular changes as described in the above winding process is processed. During winding, it is ensured that the layer-changing section of the flat wire winding (4) is located at the end of the motor, and the flat wire in the stator slot is a regular cuboid section with unchanged width and thickness. Therefore, according to the optimal parameter combination of the flat wire winding (4), combined with the position and winding path of each layer of flat wire, the length required for each layer of flat wire and the length of the layer-changing section at the winding end are planned.

4. The concentrated flat wire winding layout structure with equal cross-sectional area and high slot fill rate according to claim 1, characterized in that: The stator slot of the stator core is a semi-closed slot. The stator slot is wider near the stator core yoke portion (2) and narrower at the slot opening far from the stator core yoke portion (2). The width of the layer of flat wire closest to the stator core yoke portion (2) in the flat wire winding (4) is the largest and the thickness is the smallest. The width of several layers of flat wire gradually decreases and the thickness gradually increases from the position near the stator core yoke portion (2) to the slot opening position. The width of the layer of flat wire closest to the slot opening of the stator slot is the smallest and the thickness is the largest.

5. The layout structure of the concentrated flat wire winding with equal cross-sectional area and high slot fill factor according to claim 1, characterized in that: The flat wire winding (4) is symmetrically distributed in the stator slots on both sides of the stator core tooth portion (1) along the cross-section perpendicular to the axial direction of the stator core. The total area of the two symmetrical cross-sections of each layer of flat wire in the flat wire winding (4) is the same.

6. The layout structure of the concentrated flat wire winding with equal cross-sectional area and high slot fill rate according to claim 1, characterized in that: A layer of slot insulation layer (3) is coated on the wall of the stator slot of the stator core.

7. The layout structure of the concentrated flat wire winding with equal cross-sectional area and high slot fill factor according to claim 1, characterized in that: A layer of winding insulation paint film (5) is coated on the surface of the flat wire winding (4).

Images