Method and structure for suppressing concentrated winding circulating current loss based on coil cross transposition

Abstract

The application provides a concentrated winding circulating current loss suppression method and structure based on coil cross transposition, and belongs to the technical field of motor winding design and concentrated winding loss optimization. The structure comprises a spliced stator core and a winding coil. The winding coil is formed by winding a plurality of parallel winding strands around the split teeth in a root-by-root manner. Each parallel winding strand is arranged in layers in order from inside to outside. The winding coil is provided with a selective cross transposition structure at the end according to the parity of the number of parallel winding strands. The odd number of strands are only provided with an inter-coil cross transposition structure, and the even number of strands are provided with an inter-coil cross transposition structure or an intra-coil cross transposition structure. When the application is applied to a high-speed fractional-slot concentrated winding permanent magnet motor, the circulating current loss coefficient can be reduced by more than 36.4% at a frequency of 1500 Hz, the process is simplified, the end space occupation is reduced, and the motor power density is improved.

Description

Technical Field

[0001] This invention relates to the field of motor winding design and concentrated winding loss optimization technology, specifically to a method and structure for suppressing concentrated winding circulating current loss based on coil cross-transposition. Background Technology

[0002] The electrification process in transportation, aerospace, and other fields has placed increasingly stringent demands on the power density and operating efficiency of motor systems. As a significant component of motor losses, copper losses directly affect the temperature rise characteristics and performance limits of motors, making them a key control target in thermal management and efficiency optimization.

[0003] Please see Figure 1 As shown, traditional fractional-slot concentrated winding permanent magnet motors generally operate at high frequencies. To reduce high-frequency AC losses, the stator windings typically employ a multi-strand parallel-wound, randomly stacked structure, with the strands randomly piled within the slots and directly connected at the ends without transposition. While this structure is simple to manufacture and inexpensive, it suffers from four major technical defects. First, the leakage magnetic field distribution within the slots is uneven. Due to the slot opening structure and the asymmetry of the tooth magnetic circuit, the leakage magnetic flux exhibits significant gradient differences along the slot height and width, with higher magnetic flux density at the slot opening. The fixed spatial positions of each strand result in significant differences in the linkage leakage magnetic flux linkage, leading to inconsistent induced electromotive force amplitudes and directly inducing circulating currents between the strands. Second, these circulating currents generate additional Joule losses, providing no torque output. Under high-frequency conditions, losses surge dramatically, and the superimposed load current significantly exacerbates winding heating, compressing thermal management margins and causing excessive temperature rise, severely limiting the motor's continuous operation capability and peak performance. Furthermore, the irregular arrangement of embedded flexible wires makes it impossible to utilize the mature transposition process of formed windings. Forcibly transposing the ends would increase welding nodes and insulation processes, increase end volume, and reduce slot fill factor, creating a contradiction between circulating current suppression and power density. Finally, existing optimization methods are limited to superficial solutions such as slot shape improvement and insulation upgrades, failing to fundamentally address the potential imbalance problem from the perspective of winding topology and wiring structure. A few attempts at end transposition lack systematic design and process adaptability, resulting in limited potential balancing effects and hindering large-scale industrial application.

[0004] To address the aforementioned issues, existing technologies primarily employ methods such as winding transposition, adding strand insulation layers, and optimizing slot shapes to suppress circulating currents. Transposition, in particular, alters the spatial arrangement of strands within the slots, balancing the induced potential of each strand and suppressing circulating currents at their source. However, traditional transposition methods are mostly applicable to shaped windings or regularly arranged structures, making them difficult to implement in dispersed windings. They often result in increased end dimensions, higher manufacturing complexity, and decreased slot fill factor, making it challenging to simultaneously meet the dual requirements of effective circulating current suppression and increased power density. Therefore, it is necessary to research a circulating current suppression method and structure that can achieve high efficiency, compactness, and manufacturing feasibility in dispersed winding structures. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a method and structure for suppressing concentrated winding circulating current loss based on coil cross-transposition. In this structural design, the stator core is set as a spliced ​​structure, and the coil is directly wound on the stator teeth. In the coil design, the number of turns is designed to match the slot height dimension. When the winding coil is wound, the corresponding number of turns are wound around the segmented teeth in the form of parallel strands one by one. Each parallel strand is wound in layers from the inside to the outside. This method can avoid circulating current caused by the difference in the radial direction of the motor magnetic field. Furthermore, when connecting two coils connected in series, multiple transposition solder points are added. The strands in opposite positions of the two coils are welded separately and insulated (for coils with an even number of parallel strands, the welding transposition can be performed inside the motor). This can reduce the unbalanced potential between the parallel strands, further reduce the circulating current caused by the difference in the tangential direction of the motor magnetic field, and ultimately achieve the purpose of reducing winding circulating current loss. Because the welding position is at the end and the strands are closely spaced, the method provided by this invention achieves a high slot fill factor while achieving a low circulation coefficient, which is beneficial to improving the power density of the motor and can effectively suppress the circulation loss caused by the unbalanced potential between the strands.

[0006] In a first aspect, embodiments of the present invention provide a concentrated winding circulating current loss suppression structure based on coil cross-transposition, which adopts a segmented tooth concentrated winding structure, including: The spliced ​​stator core is composed of multiple segmented teeth; A winding coil is wound on the segmented teeth; the winding coil is formed by winding multiple parallel strands around the segmented teeth one by one, and each parallel strand is arranged in layers from the inside to the outside. The selective cross-transposition structure selectively performs cross-transposition between winding coils and / or cross-transposition within winding coils based on the parity of the number of parallel strands; wherein, the cross-transposition between winding coils cross-connects the taps of the inner and outer layers of adjacent winding coils; the cross-transposition within winding coils cross-connects the taps of the inner and outer layers of strands within a single winding coil, so as to balance the induced electromotive force between the parallel strands and suppress circulating current losses.

[0007] As a further improvement of the present invention, the selective cross-transposition structure includes: When the number of parallel strands is odd, the winding coil is only provided with a cross-interchange structure between winding coils; When the number of parallel strands is even, the winding coil is provided with a cross-transposition structure between winding coils or a cross-transposition structure within winding coils. The selective cross-transposition structure achieves electrical connection of the strand taps through welding, with the transposition solder points located in the end region of the winding coil.

[0008] As a further improvement of the present invention, the winding coil includes a first coil and a second coil connected in series. The inter-winding coil cross-transposition structure includes multiple transposition solder points disposed at the ends of the first coil and the second coil. The taps of each layer of parallel strands of the first coil are welded to the corresponding taps of the second coil in reverse order and covered with an insulating layer. The innermost tap of the first coil is welded to the outermost tap of the second coil, the second innermost tap of the first coil is welded to the second outermost tap of the second coil, and so on, to form a balanced configuration of induced electromotive force in the series connection.

[0009] As a further improvement of the present invention, the winding coil cross-transposition structure includes a plurality of transposition solder points disposed at the end of a single coil; The innermost strand tap of each individual coil is welded to the outermost strand tap, the next innermost strand tap is welded to the next outermost strand tap, and the remaining strand taps are welded symmetrically in the same manner, and are covered with an insulating layer.

[0010] As a further improvement of the present invention, the segmented tooth includes a segmented tooth body; the bottom of the segmented tooth body near the outer circle of the stator core is a flat surface, and the flat surface is perpendicular to the tooth body of the segmented tooth body.

[0011] As a further improvement of the present invention, the conductor cross-section of the winding coil is circular, forming a scattered wire structure; the number of turns of the winding coil is matched with the slot height dimension of the segmented teeth, so that the wound winding coil forms a multi-layer structure in the height direction, and the number of rows distributed in each layer along the height direction is the number of coil turns, and the strands at the same height from the inside to the outside constitute and wind the strand group.

[0012] Secondly, embodiments of the present invention provide a method for suppressing circulating current losses in concentrated windings based on coil cross-transposition, which is used to prepare the aforementioned structure for suppressing circulating current losses in concentrated windings based on coil cross-transposition, and includes the following steps: S1 adopts a segmented tooth concentrated winding structure, and sets the stator core as a spliced ​​structure. The winding coil is directly wound on the segmented teeth of the stator core. The winding coil uses multiple parallel strands. During winding, the preset number of turns are wound around the segmented teeth of the stator core one strand at a time. Each parallel strand is arranged in layers from the inside to the outside. S2, depending on the parity of the number of parallel strands, selectively implement any of the following coil cross-transposition methods: When the number of parallel strands is odd, selective cross-transposition between winding coils is performed. When the number of parallel strands is even, cross-transposition between winding coils and / or cross-transposition within winding coils are selectively implemented.

[0013] As a further improvement of the present invention, the cross-transposition method between winding coils specifically includes: when connecting two winding coils connected in series, multiple transposition solder points are set at the ends, and the parallel strands in opposite relative positions of the two winding coils are individually soldered and insulated. Among them, the innermost parallel strand tap of the first coil is soldered together with the outermost parallel strand tap of the second coil, the second innermost strand tap of the first coil is soldered together with the second outermost strand tap of the second coil, and so on, to form a balanced configuration of the induced electromotive force of the strands after series connection.

[0014] As a further improvement of the present invention, the cross-transposition method within the winding coil specifically includes: within a single coil, welding the tap of the innermost parallel strand to the tap of the outermost parallel strand together, welding the tap of the next innermost parallel strand to the tap of the next outermost parallel strand together, and so on, to form a symmetrical transposition between the strands within the coil, so that the induced electromotive force of each parallel strand branch within the coil tends to be balanced.

[0015] As a further improvement of the present invention, it is applied to a high-speed fractional-slot concentrated winding permanent magnet motor to suppress circulating current loss under high-frequency current. At a current frequency of 1500Hz, the circulating current loss coefficient is reduced by more than 36.4%.

[0016] Beneficial effects: 1. This invention combines a segmented toothed concentrated winding structure with a strand-by-strand winding process to achieve a regular arrangement and consistent position of conductors in the slots. This fundamentally eliminates the difference in induced electromotive force caused by the random position of conductors in traditional scattered embedded windings, thereby avoiding circulating currents caused by differences in the radial direction of the motor's magnetic field. This lays a structural foundation for subsequent cross-transposition, allowing the circulating current suppression effect after transposition to be fully utilized, while ensuring high slot fill factor and manufacturability of machine winding.

[0017] 2. This invention constructs a method strategy for distinguishing the transposition of odd and even number of parallel-wound strands. The transposition scheme is designed differently according to the odd or even number of parallel-wound strands. Odd-numbered parallel-wound strands are forced to use cross transposition between coils, while even-numbered strands can choose to use cross transposition between coils or within coils. This avoids the structural defect that odd-numbered strands cannot be symmetrically transposed within coils, and provides a simplified alternative path for even-numbered strands.

[0018] 3. The coil cross-transposition structure provided by the present invention achieves the induced potential balance effect equivalent to coil transposition by symmetrically welding the innermost and outermost layers and the second innermost and second outermost layers of strands inside a single coil, further reducing the circulating current caused by the difference in the tangential direction of the motor magnetic field; at the same time, it halves the number of welding points required for transposition and greatly compresses the axial space occupied at the end, which is especially suitable for high-speed motors that are sensitive to end space, and further improves the power density while simplifying the process.

[0019] 4. The method provided by this invention has achieved significant technical effects on high-speed fractional-slot concentrated winding permanent magnet motors. Under the high-frequency current condition of 1500Hz, it basically eliminates circulating current loss while maintaining high slot fill factor and good process feasibility. It effectively solves the industry problem of large circulating current loss and severe temperature rise in high-speed motor windings, and provides a practical and feasible technical path for improving motor power density and reliability.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0021] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0022] Figure 1 This is a schematic diagram of a traditional coil winding structure; Figure 2 A schematic diagram of the novel winding form provided by the present invention; Figure 3 This is a schematic diagram of the coil cross-transposition structure provided in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the coil cross-transposition structure provided in Embodiment 3 of the present invention; Figure 5 This is a comparison diagram of the current vectors before and after coil cross-transposition provided in Embodiment 2 and Comparative Example 1 of the present invention; Figure 6 This is a comparison diagram of the circulating current loss coefficients before and after coil cross-transposition provided in Embodiment 2 and Comparative Example 1 of the present invention.

[0023] Explanation of reference numerals in the attached figures: 10. Divided teeth; 20. First coil; 30. Second coil; 40. Transposition solder joint. Detailed Implementation

[0024] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0026] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0029] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0030] In the description of the embodiments of the present invention, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0031] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0032] To address the technical challenge that traditional transposition methods are primarily applicable to shaped windings or regularly arranged structures, and are difficult to implement in dispersed windings with concentrated coils, often resulting in increased end dimensions, higher manufacturing complexity, and decreased slot fill factor, thus failing to simultaneously meet the dual requirements of effective circulating current suppression and increased power density, this invention provides a method and structure for suppressing circulating current losses in concentrated windings based on coil cross-transposition. Please refer to... Figures 2 to 6 As shown, this invention is based on a segmented tooth concentrated winding structure. By winding the parallel strands one by one and arranging them in layers, the invention selectively implements cross-transposition between winding coils or cross-transposition within winding coils according to the parity of the number of parallel strands. The cross-transposition within winding coils achieves the same circulating current suppression effect as the cross-transposition between winding coils by symmetrically welding the innermost and outermost, and the second innermost and second outermost strands within a single winding coil. This process is simpler and occupies less end space, thereby effectively balancing the induced electromotive force between parallel strands while maintaining a high slot fill factor, and significantly suppressing circulating current losses under high-frequency operating conditions.

[0033] Example 1 Embodiment 1 of the present invention provides a method for suppressing circulating current loss in concentrated windings based on coil cross-transposition, which is mainly applied to high-speed fractional-slot concentrated winding permanent magnet motors, and includes the following steps: S1 employs a segmented tooth concentrated winding structure, with the stator core configured as a spliced ​​structure. The winding coil is directly wound on the segmented teeth 10 of the stator core. The winding coil uses multiple parallel strands, wound one strand at a time around the stator teeth for a predetermined number of turns. Each parallel strand is arranged in layers from the inside out to maintain a regular arrangement within the slots. The predetermined number of turns matches the slot height of the stator segmented teeth 10, resulting in a multi-layered structure in the height direction. The number of rows distributed along the height direction in each layer is the number of coil turns. Strands at the same height from the inside out form a parallel strand group. The individual strand winding combined with the segmented tooth 10 structure achieves a regular arrangement of the machine winding and conductors within the slots, ensuring the consistency of the parallel strand positions within the slots. The number of parallel strands is at least two.

[0034] S2, depending on the parity of the number of strands, selectively implement any of the following cross-transposition methods: When the number of parallel strands is odd, selective cross-transposition between winding coils is performed. When the number of parallel strands is even, cross-transposition between winding coils and / or cross-transposition within winding coils are selectively implemented.

[0035] The cross-transposition is achieved by welding to make electrical connections between the strand taps, and the transposition welding point 40 is located in the end region of the winding coil.

[0036] The cross-transposition method between the winding coils specifically includes: when connecting two winding coils connected in series, multiple transposition solder points 40 are set at the ends, and the parallel strands in opposite relative positions of the two winding coils are individually soldered and insulated. The innermost parallel strand tap of the first coil 20 is soldered together with the outermost parallel strand tap of the second coil 30, the second innermost strand tap of the first coil 20 is soldered together with the second outermost strand tap of the second coil 30, and so on, to form a balanced configuration of the induced electromotive force of the strands after series connection.

[0037] The method of cross-transposition within the winding coil specifically includes: within a single coil, welding the tap of the innermost parallel strand to the tap of the outermost parallel strand together, welding the tap of the next innermost parallel strand to the tap of the next outermost parallel strand together, and so on, to form a symmetrical transposition between the strands inside the coil, so that the induced electromotive force of each parallel strand branch inside the coil tends to be balanced.

[0038] Example 2 Based on the above method, Embodiment 2 of the present invention provides a concentrated winding circulating current loss suppression structure based on coil cross-transposition, specifically adopting a segmented tooth concentrated winding structure, including: The spliced ​​stator core is composed of multiple segmented teeth 10; The winding coil is wound on the segmented teeth 10; the winding coil is formed by multiple parallel strands wound around the segmented teeth 10 one by one, and each parallel strand is arranged in layers from the inside to the outside. The selective cross-transposition structure selectively performs cross-transposition between winding coils and / or cross-transposition within winding coils based on the parity of the number of parallel strands; wherein, the cross-transposition between winding coils cross-connects the taps of the inner and outer layers of adjacent winding coils; the cross-transposition within winding coils cross-connects the taps of the inner and outer layers of strands within a single winding coil, so as to balance the induced electromotive force between the parallel strands and suppress circulating current losses.

[0039] The selective crossover structure includes: When the number of parallel strands is odd, the winding coil is only provided with a cross-interchange structure between winding coils; When the number of parallel strands is even, the winding coil is provided with a cross-transposition structure between winding coils or a cross-transposition structure within winding coils. The selective cross-transposition structure achieves electrical connection of the strand taps through welding, with the transposition solder point 40 located in the end region of the winding coil.

[0040] The winding coils include a first coil 20 and a second coil 30 connected in series; the cross-transposition structure between the winding coils includes a plurality of transposition solder points 40 disposed at the ends of the first coil 20 and the second coil 30.

[0041] The strand taps of each layer of the first coil 20 are welded to the corresponding strand taps of the second coil 30 in reverse order and covered with an insulating layer. The innermost strand tap of the first coil 20 is welded to the outermost strand tap of the second coil 30, the second innermost strand tap of the first coil 20 is welded to the second outermost strand tap of the second coil 30, and so on, to form a balanced configuration of induced potentials in the series-connected strands.

[0042] The coil cross-transposition structure includes multiple transposition solder points 40 disposed at the end of a single coil; The innermost strand tap of each individual coil is welded to the outermost strand tap, the next innermost strand tap is welded to the next outermost strand tap, and the remaining strand taps are welded symmetrically in the same manner, and are covered with an insulating layer.

[0043] The segmented tooth 10 includes a segmented tooth body; the bottom of the segmented tooth body near the outer circle of the stator core is a flat surface, and the flat surface is perpendicular to the tooth body of the segmented tooth body.

[0044] The conductor cross-section of the winding coil is circular, forming a scattered embedded wire structure; the number of turns of the winding coil is matched with the slot height dimension of the segmented teeth 10, so that the wound winding coil forms a multi-layer structure in the height direction, and the number of rows distributed along the height direction in each layer is the number of coil turns, and the strands at the same height from the inside to the outside form a strand group.

[0045] Please refer to Figure 3 As shown, in this embodiment 2, a cross-transposition structure between coils is specifically adopted, with cross-transposition between two coils as an example.

[0046] When winding the coil, multiple layers are wound around the stator core from the inside out. The number of rows distributed along the height direction in each layer is the number of turns. The strands at the same height from the inside out are called parallel strands. Taking 8 strands as an example... Figure 3 The two coils shown each have 8 parallel strands. When connected in series, they form a circuit with 8 parallel strands, each consisting of two strands connected in series. Due to the uneven distribution of the leakage magnetic field within the slot, the magnetic fields at different locations of the coils in different layers differ. Circulating currents will occur between groups 1 to 8 of parallel strands (referred to as strand 1 to strand 8) due to the different induced electromotive forces.

[0047] In this embodiment, Figure 3 Each layer of each coil is connected to a strand tap. The first coil 20 and the second coil 30 are connected in series. After cross-interchange, the innermost strand tap of the first coil 20 is welded to the outermost strand tap of the second coil 30. For example, strand 1 of the first coil 20 is connected to strand 8 of the second coil 30, strand 2 of the first coil 20 is connected to strand 7 of the second coil 30, and so on.

[0048] Assume the serial number is i The average induced electromotive force of the strands along the height direction are respectively E i ( i =1,2,3,…,8), to account for the imbalance of the magnetic field within the slot, assume E 8 < E 7 < E 6 < E 5 < E 4 < E 3 < E 2 < E 1Before cross-transposition, the joints of the strands of each coil are welded together, and the potential difference between the strands is... E 1 - E 8 After the cross-transposition, the induced electromotive force on the eight series-connected strands is shown in Table 1.

[0049] Table 1 shows the induced electromotive force on the eight series-connected strands after cross-transposition. As can be seen from Table 1, after the cross-transposition, the induced electromotive force among the eight series-connected strands is balanced, thereby reducing the circulating current between the parallel strands.

[0050] Figure 3 The cross-transposition method between the winding coils shown can be used for both schemes with an even number of parallel strands and schemes with an odd number of strands.

[0051] Example 3 For schemes where the number of parallel winding strands is even, Embodiment 3 of the present invention provides a concentrated winding circulating current loss suppression structure based on coil cross-transposition, employing, as follows: Figure 4 The cross-transposition method shown in the winding coil can further simplify the process and reduce the impact of cross-transposition on the ends.

[0052] like Figure 4 The diagram shown illustrates the cross-transposition within the winding coil of this invention. Within a single winding coil, if the number of parallel strands is even, cross-transposition within the winding coil can be achieved, thereby suppressing circulating current losses. In principle... Figure 4 The method shown is the same as Figure 3 The transposition shown is equivalent. Figure 4 The method shown forms four strands of wire wound together within a single winding coil.

[0053] The cross-transposition structure within the winding coil includes multiple transposition solder points 40 located at the ends of a single winding coil; the innermost parallel strand tap of the single winding coil is welded to the outermost parallel strand tap, the next innermost parallel strand tap is welded to the next outermost parallel strand tap, and the remaining strand taps are symmetrically welded in this manner, and covered with an insulating layer. In contrast, as... Figure 3 The method shown in Example 2 requires two winding coils to jointly form eight parallel-wound strands, and the number of series turns of each parallel-wound strand comes from both winding coils. Compared to Figure 3 The method of cross-transposition between winding coils shown is as follows: Figure 4 The cross-transposition method within the winding coil shown in Embodiment 3 can reduce the impact of cross-transposition on the ends.

[0054] In summary, the cross-transposition structure within the winding coil provided in Example 3 achieves an induced potential balance effect equivalent to the transposition between winding coils in Example 2 by symmetrically welding the innermost and outermost layers and the second innermost and second outermost layers of strands within a single coil. At the same time, it halves the number of solder points required for transposition and significantly reduces the axial space occupied at the ends, making it particularly suitable for high-speed motors that are sensitive to end space. It simplifies the process while further improving power density.

[0055] This invention combines structure, process, and selective coil cross-transfer strategy based on a segmented tooth structure, individual winding process, and selective coil cross-transfer strategy. The synergistic mechanism lies in: the coil turn count is designed to be the number of strands arranged in the height direction; the flat bottom design of the segmented tooth 10 provides a rigid reference for machine winding, allowing the strand conductors to be arranged in a deterministic sequence from the inside out along the height direction, which is the physical prerequisite for achieving precise coil cross-transfer; the individual winding process ensures that strands at the same height position have clear inner and outer layer properties, which avoids circulating currents caused by differences in the radial direction of the motor's magnetic field; Given the aforementioned positional certainty, the coil cross-transposition in this application is no longer a simple reorganization of connection relationships, but a deliberate potential complementarity pairing. This forces a balance between the high-potential region strands and the low-potential region strands, fundamentally suppressing the electromotive force difference generated by circulating current. The odd-even compatibility selection further optimizes the process path: when the number of parallel winding strands is even, the cross-transposition within the coil can avoid welding points between coils while maintaining excellent circulating current suppression effect, further reducing the circulating current caused by the difference in the tangential direction of the motor's magnetic field, ultimately achieving the goal of increasing the motor's winding circulating current loss and realizing the optimal balance between technical effect and process complexity.

[0056] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the first coil 20 and the second coil 30 are connected in series and are not cross-transposed. In engineering, all the parallel strand joints are often welded together (e.g., Figure 2 (As shown).

[0057] like Figure 5 As shown, the current vectors before and after the cross-transposition of the winding coils in Example 2 and Comparative Example 1 are illustrated. The length of the vector represents the amplitude, and the angle represents the phase angle. The blue vector represents the current vector on each parallel strand before cross-transposition (Comparative Example 1), and the red vector represents the current vector on each parallel strand after cross-transposition (Example 2). It can be seen that, compared to Comparative Example 1 without cross-transposition, the consistency of the amplitude and phase of the current vectors on the eight parallel strands is significantly improved after the coil cross-transposition in Example 2.

[0058] like Figure 6As shown, this compares the circulating current loss coefficients before and after the cross-transposition of the winding coils in Example 2 and Comparative Example 1. A higher circulating current loss coefficient indicates a larger circulating current between the parallel strands and a greater circulating current loss. It can be seen that at a current frequency of 1500Hz, the circulating current loss coefficient before cross-transposition is 1.6026, and the circulating current loss coefficient after cross-transposition is 1.0193, a reduction of 36.4%. This reflects that the circulating current between the parallel strands is significantly suppressed after cross-transposition.

[0059] It should be noted that, in other specific implementations and applications, the structure shown in this invention is not limited to the specific parameters set in the above embodiments regarding the number of groups, layers, and coils of the parallel-wound strands. These parameters are merely illustrative examples, and those skilled in the art can flexibly adjust them according to actual design requirements, electrical performance indicators, and processing conditions, and should not be construed as limiting the scope of protection of this invention in any way.

[0060] In summary, this invention provides a method and structure for suppressing circulating current losses in concentrated windings based on coil cross-transposition, belonging to the technical field of motor winding design and concentrated winding loss optimization. The structure includes a spliced ​​stator core and winding coils. The winding coils are formed by winding multiple parallel strands around segmented teeth one by one, with each parallel strand arranged in layers from the inside out. The winding coils have selective cross-transposition structures at their ends based on the parity of the number of parallel strands: odd-numbered strands only have inter-coil cross-transposition structures, while even-numbered strands have either inter-coil cross-transposition structures or intra-coil cross-transposition structures. The inter-coil cross-transposition structure welds the taps of strands in opposite relative positions in two coils connected in series; the intra-coil cross-transposition structure symmetrically welds the innermost and outermost, and the next innermost and next outermost, strand taps within a single coil. By creating conditions for transposition through a segmented tooth structure and regular arrangement, and combining an odd-even strand differentiation strategy, the induced electromotive force between the strands is effectively balanced while maintaining a high slot fill factor. This significantly suppresses circulating current loss under high-frequency operating conditions. When applied to a high-speed fractional-slot concentrated winding permanent magnet motor, the circulating current loss coefficient can be reduced by more than 36.4% at a frequency of 1500Hz. At the same time, it simplifies the process, reduces the end space occupation, and helps to improve the power density and reliability of the motor.

[0061] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A concentrated winding circulating current loss suppression structure based on coil cross-transposition, characterized in that, It adopts a segmented tooth concentrated winding structure, including: The spliced ​​stator core is composed of multiple segmented teeth; A winding coil is wound on the segmented teeth; the winding coil is formed by winding multiple parallel strands around the segmented teeth one by one, and each parallel strand is arranged in layers from the inside to the outside. The selective cross-transposition structure selectively performs cross-transposition between winding coils and / or cross-transposition within winding coils based on the parity of the number of parallel strands; wherein, the cross-transposition between winding coils cross-connects the taps of the inner and outer layers of adjacent winding coils; the cross-transposition within winding coils cross-connects the taps of the inner and outer layers of strands within a single winding coil, so as to balance the induced electromotive force between the parallel strands and suppress circulating current losses.

2. The concentrated winding circulating current loss suppression structure based on coil cross-transposition according to claim 1, characterized in that, The selective crossover structure includes: When the number of parallel strands is odd, the winding coil is only provided with a cross-interchange structure between winding coils; When the number of parallel strands is even, the winding coil is provided with a cross-transposition structure between winding coils or a cross-transposition structure within winding coils. The selective cross-transposition structure achieves electrical connection of the strand taps through welding, with the transposition solder points located in the end region of the winding coil.

3. The concentrated winding circulating current loss suppression structure based on coil cross-transposition according to claim 2, characterized in that, The winding coil includes a first coil and a second coil connected in series. The inter-winding coil cross-transposition structure includes multiple transposition solder points disposed at the ends of the first coil and the second coil. The taps of each layer of parallel strands of the first coil are welded to the corresponding taps of the second coil in reverse order and covered with an insulating layer. The innermost tap of the first coil is welded to the outermost tap of the second coil, the second innermost tap of the first coil is welded to the second outermost tap of the second coil, and so on, to form a balanced configuration of induced electromotive force in the series connection.

4. The concentrated winding circulating current loss suppression structure based on coil cross-transposition according to claim 2, characterized in that, The cross-transposition structure within the winding coil includes multiple transposition solder points disposed at the end of a single coil. The innermost strand tap of each individual coil is welded to the outermost strand tap, the next innermost strand tap is welded to the next outermost strand tap, and the remaining strand taps are welded symmetrically in the same manner, and are covered with an insulating layer.

5. The concentrated winding circulating current loss suppression structure based on coil cross-transposition according to claim 1, characterized in that, The segmented tooth includes a segmented tooth body; the bottom of the segmented tooth body near the outer circle of the stator core is a flat surface, and the flat surface is perpendicular to the tooth body of the segmented tooth body.

6. The concentrated winding circulating current loss suppression structure based on coil cross-transposition according to claim 5, characterized in that, The conductor cross-section of the winding coil is circular, forming a scattered wire structure; the number of turns of the winding coil is matched with the slot height dimension of the segmented teeth, so that the wound winding coil forms a multi-layer structure in the height direction, and the number of rows distributed along the height direction in each layer is the number of coil turns, and the strands at the same height from the inside to the outside form a strand group.

7. A method for suppressing circulating current loss in concentrated windings based on coil cross-transposition, characterized in that, The method for preparing the concentrated winding circulating current loss suppression structure based on coil cross-transposition as described in any one of claims 1 to 6 comprises the following steps: S1 adopts a segmented tooth concentrated winding structure, and sets the stator core as a spliced ​​structure. The winding coil is directly wound on the segmented teeth of the stator core. The winding coil uses multiple parallel strands. During winding, the preset number of turns are wound around the segmented teeth of the stator core one strand at a time. Each parallel strand is arranged in layers from the inside to the outside. S2, depending on the parity of the number of parallel strands, selectively implement any of the following coil cross-transposition methods: When the number of parallel strands is odd, selective cross-transposition between winding coils is performed. When the number of parallel strands is even, cross-transposition between winding coils and / or cross-transposition within winding coils are selectively implemented.

8. The method for suppressing concentrated winding circulating current loss based on coil cross-transposition according to claim 7, characterized in that, The specific process of cross-transposition between the winding coils is as follows: When connecting two winding coils connected in series, multiple transposition solder points are set at the ends. The parallel strands in opposite relative positions of the two winding coils are individually soldered and insulated. The innermost parallel strand tap of the first coil is soldered together with the outermost parallel strand tap of the second coil, the second innermost strand tap of the first coil is soldered together with the second outermost strand tap of the second coil, and so on, to form a balanced configuration of the induced electromotive force of the strands after series connection.

9. The method for suppressing concentrated winding circulating current loss based on coil cross-transposition according to claim 7, characterized in that, The specific process of cross-transposition within the winding coil is as follows: Inside a single coil, the tap of the innermost parallel strand is welded together with the tap of the outermost parallel strand, and the tap of the next innermost parallel strand is welded together with the tap of the next outermost parallel strand, and so on, to form a symmetrical transposition between the strands inside the coil, so that the induced electromotive force of each parallel strand branch inside the coil tends to be balanced.

10. The method for suppressing concentrated winding circulating current loss based on coil cross-transposition according to claim 7, characterized in that, It is applied to high-speed fractional-slot concentrated winding permanent magnet motors to suppress circulating current losses under high-frequency current. At a current frequency of 1500Hz, the circulating current loss coefficient is reduced by more than 36.4%.

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