Brushless doubly-fed motor rotor winding wiring structure and method

Abstract

The invention discloses a brushless doubly-fed motor rotor winding wiring structure and method, a rotor winding comprises two pole pairs P1 and P2, the number of rotor slots is Z. The rotor winding comprises coils with two pitches, and the coils with the two pitches are connected to form four parallel branches, each branch comprises two groups of short-pitch coils with a pitch of Y1 and a group of long-pitch coils with a pitch of Y2, the short-pitch coils and the long-pitch coils located in rotor slots are stacked in the radial direction of the rotor, and the short-pitch coils located at the end part of the rotor and extending out of the rotor slots are uniformly arranged at intervals in the first circumferential direction or the second circumferential direction; the long pitch coils which are located at the end of the rotor and extend out of the rotor grooves are arranged at intervals in the third circumferential direction or the fourth circumferential direction, the first circumferential direction, the second circumferential direction, the third circumferential direction and the fourth circumferential direction are all the circumferential directions of the rotor, and the first circumference, the second circumference, the third circumference and the fourth circumference are arranged at intervals in the axial direction of the rotor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, in particular to a brushless doubly-fed machine rotor winding connection structure and method. BACKGROUND

[0002] As a new type of AC electric machine, the brushless doubly-fed machine has its stator winding supplied by grid power and variable frequency power respectively, and has the advantages of high reliability, small required variable frequency power capacity, and adaptability to different voltage levels, etc., so it has a wide application prospect in the fields of variable frequency speed regulation of electric machines, variable speed constant frequency power generation of wind power and hydroelectric power, etc.

[0003] The core working principle of the brushless doubly-fed machine determines that its stator winding needs to have two different pole pair numbers (denoted as p1 and p2), correspondingly, its rotor winding needs to satisfy the conditions of being able to simultaneously generate magnetic motive force waves with pole pair numbers p1 and p2 and opposite rotating directions, and needs to have as high a winding coefficient as possible for both pole pair numbers p1 and p2 - this is a key prerequisite for ensuring good electromechanical energy conversion efficiency and stable operation performance of the brushless doubly-fed machine, and the rotor, as a core component for realizing this core requirement, its winding structure design directly determines the overall performance of the electric machine.

[0004] In the prior art, the slot of the winding type rotor is usually arranged with a multi-phase winding, and the ratio of the pole pair numbers p1 and p2 can be flexibly selected according to actual application requirements, among which the winding type rotor winding with a pole ratio of 1:3 has been more applied in engineering practice due to its strong adaptability. However, for the winding type rotor winding with a pole ratio of 1:3, in order to ensure that it has good harmonic suppression characteristics and avoid the influence of harmonic interference on the operation stability and efficiency of the electric machine, the existing scheme usually needs to use coils with different pitches for winding arrangement.

[0005] The above-mentioned winding design with interlaced and mixed multi-pitch coils has many technical defects in actual application: on the one hand, the interlaced arrangement of different pitch coils leads to disordered winding of the rotor winding connection process, increasing the difficulty and process complexity of winding assembly; on the other hand, this structure makes the end part of the rotor winding occupy excessive space in the axial and radial directions, not only limiting the compact design of the electric machine, but also leading to low overall power density of the electric machine; at the same time, the disordered winding end structure brings great difficulty to insulation treatment, easily causing insulation failure risk, and thus affecting the operation reliability and service life of the electric machine.

[0006] Therefore, a new type of rotor winding connection and end arrangement method is needed to replace the existing winding type brushless doubly-fed machine rotor winding with a pole ratio of 1:3, to solve the problems of disordered connection, excessive space occupation, difficult insulation treatment and low power density of the existing structure, and further improve the technical performance and engineering application value of the brushless doubly-fed machine. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the aforementioned background technology and provide a rotor winding structure and method for brushless doubly fed motors that can replace the existing 1:3 pole ratio wound brushless doubly fed motor rotor windings. This invention solves the problems of disordered wiring, excessive space occupation, difficult insulation treatment, and low power density in the existing structure, and further improves the technical performance and engineering application value of brushless doubly fed motors.

[0008] To achieve this objective, the brushless doubly fed motor rotor winding wiring structure designed in this invention includes a rotor, rotor slots, and rotor windings. The rotor windings include two pole pairs, P1 and P2, and the number of rotor slots is Z. The rotor windings include coils with two pitches, which are connected to form four parallel branches. Each branch contains two sets of short-pitch coils with a pitch of Y1 and one set of long-pitch coils with a pitch of Y2. The short-pitch coils and long-pitch coils located in the rotor slots are stacked along the radial direction of the rotor. The short-pitch coils located at the rotor end and extending out of the rotor slots are evenly spaced along the first or second circumferential direction. The long-pitch coils located at the rotor end and extending out of the rotor slots are spaced along the third or fourth circumferential direction. The first, second, third, and fourth circumferential directions are all circumferential directions of the rotor. The first, second, third, and fourth circumferential directions are spaced along the axial direction of the rotor.

[0009] Furthermore, four short-pitch coils are evenly spaced in the first circumferential direction and the second circumferential direction, respectively. The portion of each short-pitch coil located at the rotor end and extending out of the rotor slot is bent at 90° toward the rotor yoke and does not exceed 1 / 4 of the first circumference or the second circumference.

[0010] Furthermore, two long-pitch coils are arranged at intervals in the third circumferential direction and the fourth circumferential direction, respectively. The portion of each long-pitch coil located at the rotor end and extending out of the rotor slot is bent at 90° toward the rotor yoke and does not exceed 1 / 2 of the third circumference or the fourth circumference.

[0011] Furthermore, the number of pole pairs P1 is 1, the number of pole pairs P2 is 3, and the number of rotor slots Z is 96.

[0012] Furthermore, the pitch Y1 of the short-pitch coil is 14; "—" represents the coil connection between two rotor slots, and "1-96" represents the rotor slots; the connection routes of the eight groups of short-pitch coils belonging to the four parallel branches are as follows:

[0013] A2: 6-24-7-23-8-22-9-21-10-21;

[0014] A3: 35-53-36-52-37-51-38-50-39-49;

[0015] B2: 54-72-55-71-56-70-57-69-58-68;

[0016] B3:83-5-84-4-85-3-86-2-87-1;

[0017] C2: 30-48-31-47-32-46-33-45-34-44;

[0018] C3: 59-77-60-76-61-75-62-74-63-73;

[0019] D2: 78-96-79-95-80-94-81-93-82-92;

[0020] D3: 11-29-12-28-13-27-14-26-15-25.

[0021] Furthermore, the pitch Y2 of the long-pitch coil is 39, with "—" indicating the coil connection between two rotor slots and "1-96" representing the rotor slots; the connection routes of the four groups of long-pitch coils belonging to the four parallel branches are as follows:

[0022] A1: 6-53-7-52-8-51-9-50-10-49-11-48-12-47-13-46-14-45;

[0023] B1: 54-5-55-4-56-3-57-2-58-1-59-96-60-95-61-94-62-93;

[0024] C1: 30-77-31-76-32-75-33-74-34-73-35-72-36-71-37-70-38-69;

[0025] D1: 78-29-79-28-80-27-81-26-82-25-83-24-84-23-85-22-86-21.

[0026] Furthermore, the pitch Y1 of the short-pitch coil is 14, and the pitch Y2 of the long-pitch coil is 39. A "—" indicates the coil connection between two rotor slots, and "1-96" represents the rotor slot. The connection routes of the four parallel branches are as follows:

[0027] A: 6-24-7-23-8-22-9-21-10-21-6-53-7-52-8-51-9-50-10-49-11-48-12-47-13-46-14-45-35-53-36-52-37-51-38-50-39-49;

[0028] B: 54-72-55-71-56-70-57-69-58-68-54-5-55-4-56-3-57-2-58-1-59-96-60-95-61-94-62-93-83-5-84-4-85-3-86-2-87-1;

[0029] C: 30-48-31-47-32-46-33-45-34-44-30-77-31-76-32-75-33-74-34-73-35-72-36-71-37-70-38-69-59-77-60-76-61-75-62-74-63-73;

[0030] D: 78-96-79-95-80-94-81-93-82-92-78-29-79-28-80-27-81-26-82-25-83-24-84-23-85-22-86-21-11-29-12-28-13-27-14-26-15-25.

[0031] Furthermore, a method for wiring the rotor windings of a brushless doubly-fed motor based on its rotor winding wiring structure includes the following steps:

[0032] At least one first copper conductor bar is placed in the rotor slot near the rotor yoke, and the at least one first copper conductor bar is wound in a concentric winding manner to form four sets of the long pitch coils.

[0033] At least one second copper conductor bar is placed on the side of the rotor slot near the outer circle of the rotor, and the at least one second copper conductor bar is wound in a concentric winding manner to form eight sets of the short pitch coils.

[0034] Each of the two ends of the long-pitch coil is connected to one end of a short-pitch coil to form four parallel branches.

[0035] Furthermore, it also includes the following steps: bending the two ends of each group of long-pitch coils and the two ends of each group of short-pitch coils towards the rotor yoke at a 90° angle.

[0036] Furthermore, it also includes the following steps: arranging the ends of the eight sets of short-pitch coils along the first circumferential direction or the second circumferential direction, such that the ends of four sets of short-pitch coils are evenly spaced along the first circumferential direction and the second circumferential direction respectively; arranging the ends of the four sets of long-pitch coils along the third circumferential direction or the fourth circumferential direction, such that the ends of two sets of long-pitch coils are spaced along the third circumferential direction and the fourth circumferential direction respectively.

[0037] The beneficial effects of this invention are as follows: By optimizing the selection of coil pitch, branch connection method, and end arrangement structure, this invention solves the core defects of existing 1:3 pole ratio wound rotor windings, significantly improving the practicality and reliability of brushless doubly-fed motors. Its core advantages are as follows:

[0038] 1. The fixed combination mode of "short pitch coil + long pitch coil" is adopted, and the connection route of the four parallel branches is clear, which avoids the disorderly winding of coils with different pitches and simplifies the winding assembly process.

[0039] 2. The coils in the slot are stacked in layers along the radial direction, and the ends are arranged at intervals in different circumferential directions and bent at 90°, which greatly reduces the axial and radial space occupation, making it possible to make the motor compact design possible and indirectly improving the power density.

[0040] 3. The rotor windings avoid wire crossing and compression through an orderly end arrangement structure, reducing the risk of insulation layer damage and extending the service life of the motor.

[0041] 4. Targeted selection of short pitch Y1=14 and long pitch Y2=39, combined with a 96-slot rotor design, ensures that the winding coefficients corresponding to pole pairs 1 and 3 are at a high level, guaranteeing electromechanical energy conversion efficiency.

[0042] 5. Each of the four parallel branches consists of "two sets of short-pitch coils + one set of long-pitch coils", with a symmetrical and unified structure and stronger operational stability. The short-pitch coils have two turns (4 sets each) at the end and the long-pitch coils have two turns (2 sets each) at the end, evenly arranged in circumferential intervals along the axial direction, further optimizing space utilization.

[0043] 6. The layered winding method of "winding the long-pitch coil first and then the short-pitch coil" is adopted, combined with the end bending process, and the operation process is clear and reproducible.

[0044] In summary, this invention precisely matches the engineering application scenario of a pole ratio of 1:3 through structure and method, and balances harmonic suppression characteristics and process feasibility through structural optimization, making the brushless doubly fed motor more competitive in the fields of variable frequency speed regulation and new energy power generation, and providing an effective solution for the miniaturization and high reliability design of motors. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments disclosed in this invention, the accompanying drawings of the embodiments will be briefly described below. These drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0046] Figure 1 This is a schematic diagram of the rotor winding structure formed by concentric winding in this invention;

[0047] Figure 2 This is a three-dimensional view of the stacked short-pitch coil and long-pitch coil in this invention;

[0048] Figure 3 This is a schematic diagram of the rotor structure in this invention;

[0049] Figure 4 This is a front view of the long-pitch coils distributed along the circumferential direction in this invention;

[0050] Figure 5 This is a front view of the short-pitch coils distributed along the circumferential direction in this invention;

[0051] Wherein, 1—rotor (1.1—shaft, 1.2—rotor core), 2—rotor slot, 3—rotor winding, 4—short pitch coil, 5—long pitch coil. Detailed Implementation

[0052] The technical solutions (including preferred technical solutions) of the present invention will be further described in detail below with reference to the accompanying drawings and by way of listing some optional embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] A specific embodiment of the rotor winding wiring structure of a brushless doubly fed motor is provided:

[0055] like Figure 1 As shown in Figure 5, this embodiment provides a rotor winding connection structure for a brushless doubly fed motor with a pole ratio of 1:3, which is suitable for 96-slot rotor designs and can meet the application requirements of scenarios such as variable frequency speed regulation and new energy power generation.

[0056] Core parameter settings:

[0057] Pole pairs: P1=1 (few pole pairs), P2=3 (multiple pole pairs).

[0058] The number of rotor slots Z=96, and rotor slots 2 are evenly distributed along the circumferential direction of the rotor core 1.2 surface.

[0059] Coil pitch: short pitch coil Y1=14, long pitch coil Y2=39.

[0060] Number of branches: Four parallel branches (marked as A, B, C, and D), each branch containing two sets of short-pitch coils and one set of long-pitch coils.

[0061] Coil group composition and connection route: Short pitch coil group (8 groups in total, belonging to four branches):

[0062] Branch A: Group A2 (slot numbers 6-24-7-23-8-22-9-21-10-21), Group A3 (slot numbers 35-53-36-52-37-51-38-50-39-49).

[0063] Branch B: Group B2 (slot numbers 54-72-55-71-56-70-57-69-58-68), Group B3 (slot numbers 83-5-84-4-85-3-86-2-87-1).

[0064] Branch C: Group C2 (slot numbers 30-48-31-47-32-46-33-45-34-44), Group C3 (slot numbers 59-77-60-76-61-75-62-74-63-73).

[0065] Branch D: Group D2 (slot numbers 78-96-79-95-80-94-81-93-82-92), Group D3 (slot numbers 11-29-12-28-13-27-14-26-15-25).

[0066] Long-pitch coil groups (4 groups in total, belonging to four branches):

[0067] Branch A, Group A1: Slot numbers 6-53-7-52-8-51-9-50-10-49-11-48-12-47-13-46-14-45.

[0068] Branch Road B1 Group: Slot No. 54-5-55-4-56-3-57-2-58-1-59-96-60-95-61-94-62-93.

[0069] Branch C, Group C1: Slot numbers 30-77-31-76-32-75-33-74-34-73-35-72-36-71-37-70-38-69.

[0070] Branch D, Group D1: Slot number 78—29—79—28—80—27—81—26—82—25—83—24—84—23—85—22—86—213.

[0071] Branch line overall connection:

[0072] Branch Route A: Group A2 → Group A1 → Group A3, the complete route is 6—24—7—23—8—22—9—21—10—21—6—53—7—52—8—51—9—50—10—49—11—48—12—47—13—46—14—45—35—53—36—52—37—51—38—50—39—49.

[0073] Branches B, C, and D are formed by connecting the corresponding short-pitch coil group and long-pitch coil group in series, following the same logic as above.

[0074] Structural layout details:

[0075] Slot arrangement: Short-pitch coils (upper layer) are placed close to the outer circumference of the rotor, and long-pitch coils (lower layer) are placed close to the rotor yoke, stacked radially in parallel layers. End arrangement: The ends of short-pitch coils are arranged along the first and second circumferential directions (4 groups evenly spaced each), and the ends of long-pitch coils are arranged along the third and fourth circumferential directions (2 groups spaced each). The four circumferences are arranged axially at intervals, with a spacing greater than the width of the coil end conductor. End bending: All coils extending out of the rotor slot are bent at 90° towards the rotor yoke. The ends of short-pitch coils do not exceed 1 / 4 of the corresponding circumference, and the ends of long-pitch coils do not exceed 1 / 2 of the corresponding circumference.

[0076] Example 2

[0077] Based on the wiring structure of Embodiment 1, a specific winding process for the rotor winding of a brushless doubly-fed motor is provided, with the following steps:

[0078] Prepare a 96-slot rotor core (including rotor slot 2), a first copper conductor bar (for long-pitch coils), and a second copper conductor bar (for short-pitch coils). The conductor bar specifications should be adapted to the motor power requirements.

[0079] Confirm the winding tools: concentric winding mold, bending tool, and insulation material, ensuring that the tool accuracy meets the requirements for conductor bending and coil forming.

[0080] Core winding steps:

[0081] 1. Long-pitch coils are wound and installed in the lower layer of the rotor slot 2 near the rotor yoke. The first copper conductor is placed parallel to the first copper conductor. The coils are wound in a concentric winding manner to form four groups of long-pitch coils: A1, B1, C1, and D1, with a span of 18 slots per group (Y2=39). During the winding process, the coils are guaranteed to be single-turn quadrilateral structures, and adjacent coils are connected in series in sequence. The conductors in the slots are arranged neatly without crossing.

[0082] 2. Short-pitch coil winding and installation: In the upper layer position near the outer circle of the rotor in the rotor slot 2, place the second copper conductor bar in parallel. With a span of 10 slots per group (Y1=14), use concentric winding to form eight groups of short-pitch coils, namely A2, A3, B2, and B3. Ensure that the upper and lower conductor bars are parallel and aligned, and that there is no radial interference with the lower long-pitch coil.

[0083] 3. Branch series connection: Following the order of "short pitch coil group → long pitch coil group → short pitch coil group", the two ends of each long pitch coil group are welded to one end of the corresponding two short pitch coil groups. The connection points are wrapped with insulating material to ensure electrical isolation between the branches, forming four independent parallel branches A, B, C, and D.

[0084] 4. End bending and arrangement: Use a bending tool to bend the straight portions of all coils extending out of the rotor slots at 90° toward the rotor yoke, controlling the bending angle accuracy to avoid damage to the guide bars.

[0085] 5. Arrange the ends according to the preset circumferential plane: Arrange the ends of the short-pitch coils of groups A2, B2, C2, and D2 on the first circumference, and arrange the ends of groups A3, B3, C3, and D3 on the second circumference; arrange the ends of the long-pitch coils of groups A1 and B1 on the third circumference, and arrange the ends of groups C1 and D1 on the fourth circumference, to ensure uniform axial spacing.

[0086] 6. Insulation and Fixing: Insulate the coil end connection points and conductor surface using high-temperature resistant insulating tape, ensuring the insulation layer is undamaged. Check that all coils are arranged in an orderly manner without crossing or squeezing. Secure the end coils circumferentially with fasteners to prevent loosening during operation.

[0087] 7. Quality Inspection: Inspect the continuity of the four branches to ensure there are no open circuits or short circuits.

[0088] 8. Dimensional verification: Measure the axial and radial space occupied at the end to verify whether it meets the compact design requirements.

[0089] 9. Insulation test: The insulation performance between branches and between the coil and the rotor core is tested using an insulation resistance meter to ensure that the insulation performance meets the motor operation insulation standards.

[0090] In summary, Example 1 focuses on the rotor winding structure of a 1:3 pole ratio, 96-slot brushless doubly-fed motor. By setting the short pitch Y1=14 and the long pitch Y2=39, four parallel branches containing "two sets of short-pitch coils + one set of long-pitch coils" are constructed. The connection routes of each coil group's slot number are clearly defined. At the same time, radial layering within the slots, multi-circular axial spacing at the ends, and 90° bending design are adopted to form an orderly structure. Example 2 provides a winding method corresponding to this structure. With concentric winding as the core, the winding is carried out in the order of "lower layer long-pitch coils first, then upper layer short-pitch coils". Then, the winding assembly is completed by connecting branches in series, bending the ends, and fixing with insulation.

[0091] Both technologies offer significant advantages: First, they feature an ordered structure and process: fixed branch combinations and clear connection routes, coupled with a layered winding process, avoid disordered coil winding, significantly reduce assembly difficulty, and improve process reproducibility. Second, they offer high space utilization: radial stacking within the slots and multi-circular spacing at the ends reduce axial and radial space occupation, laying the foundation for compact motor design and indirectly increasing power density. Third, they offer strong reliability: orderly arrangement at the ends avoids cross-extrusion of conductor bars, and standardized insulation treatment reduces the risk of insulation failure and extends motor life. Fourth, they guarantee performance: targeted pitch selection and a 96-slot design ensure high winding coefficients for pole pairs 1 and 3, guaranteeing electromechanical energy conversion efficiency while also considering harmonic suppression characteristics, making them suitable for scenarios such as variable frequency speed control and new energy power generation.

[0092] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting itself to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of this specification to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims. When using terms such as "comprising," "having," and "including" as described in this specification, there may also be another part or other components, and the terms used are generally singular but may also represent plural forms. It should be pointed out that although various different components may appear and be described in this specification using terms such as "first," "second," "top," "bottom," "one side," "the other side," "one end," "the other end," etc., these components and parts should not be limited by these terms. These terms are only used to distinguish one component and part from another component and part. For example, without departing from the scope of this specification, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component; top and bottom components may, in certain cases, be interchanged or converted; components at one end and at the other end may have the same or different performance characteristics.

[0093] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A brushless doubly-fed machine rotor winding connection structure comprising a rotor (1), rotor slots (2) and rotor windings (3), the rotor windings (3) comprising two pole pair numbers P1 and P2, the number of rotor slots (2) being Z, characterised in that: The rotor winding (3) includes two kinds of pitch coils connected to form four parallel branches, each branch containing two groups of short pitch coils (4) with a pitch Y1 and a group of long pitch coils (5) with a pitch Y2, the short pitch coils (4) and the long pitch coils (5) in the rotor slot (2) are arranged in a radial direction of the rotor (1), the short pitch coils (4) at the end of the rotor (1) and extending out of the rotor slot (2) are uniformly spaced in a first circumferential direction or a second circumferential direction, the long pitch coils (5) at the end of the rotor (1) and extending out of the rotor slot (2) are spaced in a third circumferential direction or a fourth circumferential direction, the first circumferential direction, the second circumferential direction, the third circumferential direction and the fourth circumferential direction are all circumferential directions of the rotor (1), and the first, second, third and fourth circumferences are arranged in an axial direction of the rotor.

2. The brushless doubly-fed machine rotor winding connection structure of claim 1, wherein: The first and second circumferential directions are uniformly spaced by four short pitch coils (4), and each short pitch coil (4) is bent by 90° towards the rotor yoke direction at the end of the rotor (1) and extends out of the rotor slot (2) by not more than 1 / 4 of the first or second circumference.

3. The brushless doubly-fed machine rotor winding connection structure of claim 1, wherein: The third and fourth circumferential directions are spaced by two long pitch coils (5), and each long pitch coil (5) is bent by 90° towards the rotor yoke direction at the end of the rotor (1) and extends out of the rotor slot (2) by not more than 1 / 2 of the third or fourth circumference.

4. The brushless doubly-fed machine rotor winding connection structure of claim 1, wherein: The pole pair number P1 is 1, the pole pair number P2 is 3, and the rotor slot number Z is 96.

5. A brushless doubly-fed machine rotor winding connection structure as claimed in claim 1 or 2 characterised in that: The pitch Y1 of the short pitch coil (4) is 14, the connection part between two rotor slots (2) is represented by "--", and the rotor slot (2) is represented by "1-96"; the connection routes of the eight groups of short pitch coils (4) belonging to four parallel branches are as follows: A2：6—24—7—23—8—22—9—21—10—21； A3：35—53—36—52—37—51—38—50—39—49； B2：54—72—55—71—56—70—57—69—58—68； B3：83—5—84—4—85—3—86—2—87—1； C2：30—48—31—47—32—46—33—45—34—44； C3：59—77—60—76—61—75—62—74—63—73； D2：78—96—79—95—80—94—81—93—82—92； D3：11—29—12—28—13—27—14—26—15—25。 6. A brushless doubly-fed machine rotor winding connection structure as claimed in claim 1 or 3 characterised in that: The pitch Y2 of the long pitch coil (5) is 39, the connection part between two rotor slots (2) is represented by "--", and the rotor slot (2) is represented by "1-96"; the connection routes of the four groups of long pitch coils (5) belonging to four parallel branches are as follows: A1：6—53—7—52—8—51—9—50—10—49—11—48—12—47—13—46—14—45； B1：54—5—55—4—56—3—57—2—58—1—59—96—60—95—61—94—62—93； C1：30—77—31—76—32—75—33—74—34—73—35—72—36—71—37—70—38—69； D1：78—29—79—28—80—27—81—26—82—25—83—24—84—23—85—22—86—21。 7. A brushless doubly-fed machine rotor winding connection structure as claimed in claim 1 or 2 or 3 characterised in that: The pitch Y1 of the short pitch coil (4) is 14, the pitch Y2 of the long pitch coil (5) is 39, the connection part between two rotor slots (2) is represented by "--", and the rotor slot (2) is represented by "1-96"; the connection routes of the four parallel branches are as follows: A：6—24—7—23—8—22—9—21—10—21—6—53—7—52—8—51—9—50—10—49—11—48—12—47—13—46—14—45—35—53—36—52—37—51—38—50—39—49； B：54—72—55—71—56—70—57—69—58—68—54—5—55—4—56—3—57—2—58—1—59—96—60—95—61—94—62—93—83—5—84—4—85—3—86—2—87—1； C：30—48—31—47—32—46—33—45—34—44—30—77—31—76—32—75—33—74—34—73—35—72—36—71—37—70—38—69—59—77—60—76—61—75—62—74—63—73； D：78—96—79—95—80—94—81—93—82—92—78—29—79—28—80—27—81—26—82—25—83—24—84—23—85—22—86—21—11—29—12—28—13—27—14—26—15—25。 8. A method of connecting the windings of a rotor of a brushless doubly-fed machine, based on the structure of the windings of a rotor of a brushless doubly-fed machine according to any one of claims 1 to 7, characterised in that: It comprises the following steps: At least one first copper conductor is placed in the rotor slot (2) near the rotor yoke, and at least one first copper conductor is wound to form four groups of long pitch coils (5) in a concentric winding manner; At least one second copper bar is placed at the side of the rotor slot (2) close to the rotor outer circle, and the at least one second copper bar is wound in a concentric manner to form eight groups of the short-pitch coils (4); The two ends of each group of the long-pitch coils (5) are respectively connected with one end of one group of the short-pitch coils (4), to form four parallel branches.

9. The method of claim 8, wherein: It further comprises the following steps: the two ends of each group of the long-pitch coils (5) and the two ends of each group of the short-pitch coils (4) are bent by 90° towards the rotor yoke.

10. The method of claim 9, wherein: It further comprises the following steps: the ends of the eight groups of the short-pitch coils (4) are arranged along the first circumferential direction or the second circumferential direction, and the first circumferential direction and the second circumferential direction are respectively and uniformly spaced with the ends of four groups of the short-pitch coils (4); the ends of the four groups of the long-pitch coils (5) are arranged along the third circumferential direction or the fourth circumferential direction, and the third circumferential direction and the fourth circumferential direction are respectively and spaced with the ends of two groups of the long-pitch coils (5).

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