Processing method of litz wire coil for wind power motor stator

Abstract

The invention discloses a processing method of a litz wire coil for a wind power motor stator, and the method comprises the following steps: coating for the first time: coating the surface of a substrate with a first insulating layer to form a single wire; twisting and back-twisting: twisting the plurality of single wires coated with the first insulating layers, and then twisting; a constant-tension active back-twisting mode is adopted, the tension is constant when each enameled wire bundle is twisted, meanwhile, the twisting direction is opposite to the rotating direction of a single disc, back-twisting, repeated twisting and back-twisting operation are achieved, and a twisted wire bundle is formed; square pressing: pressing the plurality of twisted wire harnesses into a predetermined shape; coating again: coating the squared wire harness with a second insulating layer to form the Litz wire; and winding: winding the Litz wire into a stator coil of the wind power motor. According to the invention, a constant-tension active back-twisting mode is adopted, the tension is constant when each enameled wire bundle is twisted, the twisting direction is opposite to the rotation direction of a single disc, back-twisting is realized, and the insulating property and durability of a stator coil can be effectively improved.

Description

Technical Field

[0001] The invention relates to a method for processing a litz wire coil for a wind turbine motor stator, in particular to a method for processing a litz wire coil for a wind turbine motor stator. Background Art

[0002] Wind power generation converts the kinetic energy of wind into electrical energy. Wind power generation is gaining popularity worldwide because it requires no fuel and produces no radiation or air pollution. Wind energy, a clean, pollution-free, renewable energy source, has long been used, primarily through windmills for pumping water and grinding flour. However, greater interest has arisen in harnessing the wind to generate electricity. Wind power generation utilizes wind power to rotate windmill blades, which are then accelerated by a speed increaser, driving the generator to generate electricity. According to windmill technology, electricity generation can be initiated with a breeze of approximately three meters per second (a gentle breeze).

[0003] Wind power generation is environmentally friendly and boasts enormous potential, attracting increasing attention worldwide. my country boasts abundant wind energy resources, with approximately 100 GW of exploitable wind energy reserves. This includes approximately 253 GW of onshore wind energy reserves (based on data at a height of 10 meters above the ground) and approximately 750 GW of offshore wind energy reserves, totaling 100 GW. By the end of June 2023, China's installed wind power capacity was approximately 390 GW, a year-on-year increase of 13.7%. At the end of 2003, the nation's installed power capacity was approximately 567 GW.

[0004] This patent is designed to address the challenges of lightweighting the structure of wind turbine motors and increasing their power density, while also meeting the complex domestic operating conditions (wind, sand, acid, and alkali) and enhancing the insulation and durability of the stator coils. This patent is designed to compensate for the shortcomings of electromagnetic wires. Summary of the Invention

[0005] In order to solve the defects of the above-mentioned prior art, the present invention provides a method for processing Litz wire coils for wind turbine stators. The present invention adopts a constant tension active detwisting method to keep the tension of each enameled wire bundle constant when twisting. At the same time, the twisting direction is opposite to the rotation direction of the single disk to achieve detwisting, which can effectively improve the insulation performance and durability of the stator coil.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution: A method for processing a litz wire coil for a wind turbine stator, comprising the following steps:

[0007] First coating: coating the substrate surface with a first insulating layer to form a single conductor;

[0008] In the first coating step, the first insulating layer is a modified polyamide-imide insulating layer, and the thickness of the modified polyamide-imide insulating layer is 0.001 mm to 0.016 mm; the substrate is a round wire made of Cu-TU1;

[0009] Twisting and untwisting: twisting multiple single conductors coated with the first insulation layer, and then untwisting them;

[0010] In the twisting and untwisting step, a constant tension active untwisting method is adopted to keep the tension of each enameled wire bundle constant when twisting, and the twisting direction is opposite to the rotation direction of the single drum to achieve untwisting. The twisting and untwisting operations are repeated multiple times to form a twisted wire bundle;

[0011] Pressing: Pressing multiple twisted wires into a predetermined shape;

[0012] Re-coating: The squared wire bundle is coated with a second insulation layer to form a Litz wire;

[0013] In the re-coating step, the second insulating layer is a polyesterimide reinforced mica insulating layer, and the thickness of the polyesterimide reinforced mica insulating layer is greater than the thickness of the modified polyamideimide insulating layer;

[0014] Winding: Litz wire is wound into wind turbine stator coils.

[0015] In the twisting and untwisting step, multiple single wires are twisted and untwisted to form a twisted wire bundle, and then the multiple twisted wire bundles are twisted and untwisted again in the twisting and untwisting manner to form a secondary twisted wire bundle, and then the multiple secondary twisted wire bundles are twisted and untwisted again in the twisting and untwisting manner to form a composite twisted wire bundle.

[0016] There are 420 single conductors, which are divided into 42 groups with 10 conductors in each group. The 10 single conductors are forward twisted and reversely twisted to form a twisted wire harness, resulting in a total of 42 twisted wire harnesses. The 42 twisted wire harnesses are divided into 6 groups with 7 conductors in each group. The 7 twisted wire harnesses are forward twisted and reversely twisted to form a secondary twisted wire harness, resulting in a total of 6 secondary twisted wire harnesses. The 6 secondary twisted wire harnesses are divided into 2 groups with 3 conductors in each group. The 3 secondary twisted wire harnesses are forward twisted and reversely twisted to form a composite twisted wire harness, resulting in a total of 2 composite twisted wire harnesses. The 2 composite twisted wire harnesses are finally forward twisted and reversely twisted to form a final wire harness.

[0017] Twisting refers to twisting the basic conductor in a clockwise spiral structure during the twisting process, and backtwisting refers to backtwisting by the same number of turns in the opposite direction of the twisting.

[0018] When using twisting equipment, the tension of the equipment is constant during the twisting and untwisting process.

[0019] During the initial insulation coating process, a multi-pass coating method is adopted.

[0020] Before squaring, the process also includes wrapping the wire core with a film, where the core refers to the twisted wire bundle formed during the twisting and untwisting step. The twisted wire bundle is wrapped in a layer of plastic film in a clockwise direction to reduce damage to the wire bundle during squaring. The squaring die is typically made of metal. When the twisted Litz wire passes through the four corners of the square die, the outer conductors of the Litz wire are subjected to significant pressure and friction, which can cause deformation and damage to the paint coating. Twisted Litz wire is not a single wire or a fixed number of wires in the outer layer. Instead, as the twist spiral is twisted, each enameled wire in the Litz wire continuously changes position according to the twisting sequence. Therefore, as the length of the Litz wire increases, each enameled wire continuously appears in the outer layer according to the twist pitch. In other words, each enameled wire will appear in the four corners of the metal squaring die many times. The longer the Litz wire, the greater the probability of occurrence and the greater the degree of damage to the enameled wire. Therefore, the formed Litz wire will experience a large number of broken wires and short circuits between wires due to paint damage. Before squaring, a layer of 0.05mm insulation film is first wrapped around the stranded round Litz wire halfway. When the round Litz wire wrapped with insulation film passes through the squaring die, the film is always the outer layer that bears the force. The die size is adjusted to the size of the Litz wire after the insulation layer is wrapped. This prevents damage to the enameled wire during the squaring process and does not increase the size of the Litz wire after squaring. The film can be removed after squaring.

[0021] During the re-insulation coating process, a multi-pass coating method is adopted.

[0022] It also includes the Litz wire testing steps: break up the squared Litz wire, randomly select 80 single conductors to measure their withstand voltage values, randomly select 6 twisted wire harnesses to measure their withstand voltage values, randomly select 4 secondary twisted wire harnesses to measure their withstand voltage values, measure the withstand voltage values ​​of 2 composite twisted wire harnesses, and measure the withstand voltage value of 1 final wire harness.

[0023] In summary, the present invention has achieved the following technical effects:

[0024] The present invention adopts a constant tension active back-twisting method to keep the tension of each enameled wire bundle constant when twisting. At the same time, the twisting direction is opposite to the rotation direction of the single disk to achieve back-twisting, which can effectively improve the insulation performance and durability of the stator coil.

[0025] During the first insulation coating process, a multi-pass coating method is adopted. In addition, by increasing the coating thickness of the first modified polyamide-imide, the bonding strength of the organic and inorganic materials is improved, the self-leveling of the insulating paint is enhanced, and oxygen is better isolated to avoid oxidation of the copper conductor.

[0026] During the secondary insulation coating process, a multi-pass coating method is used. By increasing the number of coats of the modified polyesterimide insulation layer and raising the temperature in the preheating zones 1 and 2 of the oven, the insulating varnish layer enters a viscous state more quickly. This lowers the temperature in the curing zone, preventing the entire insulation layer from excessively entering a vitreous state, making it easier to obtain a highly flexible film and improving the overall workability of the magnet wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic cross-sectional view of a twisted wire harness provided by an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the cross section of Litz wire. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0033] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0034] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0035] Example:

[0036] A method for processing a litz wire coil for a wind turbine stator comprises the following steps:

[0037] First coating: coating the surface of the substrate 1 with a first insulating layer 2 to form a single conductor;

[0038] In the first coating step, the first insulating layer is a modified polyamide-imide insulating layer, and the thickness of the modified polyamide-imide insulating layer is 0.001 mm to 0.016 mm; the substrate is a round wire made of Cu-TU1;

[0039] Twisting and untwisting: twisting multiple single conductors coated with the first insulation layer, and then untwisting them;

[0040] In the twisting and untwisting step, a constant tension active untwisting method is adopted to keep the tension of each enameled wire bundle constant when twisting, and the twisting direction is opposite to the rotation direction of the single drum to achieve untwisting. The twisting and untwisting operations are repeated multiple times to form a twisted wire bundle;

[0041] Pressing: Pressing multiple twisted wires into a predetermined shape;

[0042] Re-coating: Coating the squared wire bundle with a second insulating layer 3 to form a Litz wire;

[0043] In the re-coating step, the second insulating layer is a polyesterimide reinforced mica insulating layer, and the thickness of the polyesterimide reinforced mica insulating layer is greater than the thickness of the modified polyamideimide insulating layer;

[0044] Winding: Litz wire is wound into wind turbine stator coils.

[0045] Specifically, in the twisting and untwisting step, multiple single wires are twisted and untwisted to form a twisted wire bundle, and then the multiple twisted wire bundles are twisted and untwisted again in the twisting and untwisting manner to form a secondary twisted wire bundle, and then the multiple secondary twisted wire bundles are twisted and untwisted again in the twisting and untwisting manner to form a composite twisted wire bundle.

[0046] In this embodiment, the number of single conductors is 420. The single conductors are divided into 42 groups, each with 10 conductors. The 10 single conductors are forward twisted and reversely twisted to form a twisted wire bundle, resulting in a total of 42 twisted wire bundles. The 42 twisted wire bundles are divided into 6 groups, each with 7 conductors. The 7 twisted wire bundles are forward twisted and reversely twisted to form a secondary twisted wire bundle, resulting in a total of 6 secondary twisted wire bundles. The 6 secondary twisted wire bundles are divided into 2 groups, each with 3 conductors. The 3 secondary twisted wire bundles are forward twisted and reversely twisted to form a composite twisted wire bundle, resulting in a total of 2 composite twisted wire bundles. The 2 composite twisted wire bundles are finally forward twisted and reversely twisted to form a final wire bundle.

[0047] Twisting refers to twisting the basic wires in a clockwise spiral structure during the twisting process, and backtwisting refers to backtwisting by retracting the same number of turns in the opposite direction of twisting. Specifically, the multiple single wires are gathered together, clamped at both ends with a first clamp, and the first clamp is tightened. The tail is connected to a rotating device, and the rotating device rotates one circle in the forward direction, holds for a certain period of time, and then rotates one circle in the reverse direction to achieve backtwisting. A constant tension active backtwisting method is used to maintain a constant tension when twisting each enameled wire bundle. At the same time, the twisting direction is opposite to the rotation direction of the single reel to achieve backtwisting.

[0048] During the twisting and untwisting process, the twisting equipment has a constant tension, which ensures constant twisting and untwisting and improves the quality of the litz wire.

[0049] During the first insulation coating process, a multi-pass coating method is adopted. In addition, by increasing the coating thickness of the first modified polyamide-imide, the bonding strength of the organic material and the inorganic material is improved, the self-leveling of the insulating paint is enhanced, and oxygen is better isolated to avoid oxidation of the copper conductor.

[0050] During the secondary insulation coating process, a multi-pass coating method is used. By increasing the number of coats of the modified polyesterimide insulation layer and raising the temperature in the preheating zones 1 and 2 of the oven, the insulating varnish layer enters a viscous state more quickly. This lowers the temperature in the curing zone, preventing the entire insulation layer from excessively entering a vitreous state, making it easier to obtain a highly flexible film and improving the overall workability of the magnet wire.

[0051] During the squaring step, the fully twisted wire passes through a Turkish head for active squaring. The four sides of the wire are evenly stressed and the deformation is controllable, and the stress is naturally released, thus obtaining a whole strand of twisted wire.

[0052] The base 1 is enameled wire, with its shape, specifications, ability to withstand short-term and long-term high-temperature operation, strong vibration and centrifugal forces at high speeds in certain applications, corona and breakdown resistance under high voltage, and chemical corrosion resistance in special atmospheres. The electromagnetic wire used for winding must withstand stretching, bending, and abrasion during winding and embedding, as well as swelling and corrosion during impregnation and drying. Electromagnetic wire can be categorized by its basic components, the conductive core and the insulating layer. Generally, it is categorized into enameled wire, wrapped wire, enameled wrapped wire, and inorganic insulated wire, depending on the insulating material used and the manufacturing method of the insulating layer.

[0053] Each set of enameled wire is twisted into a single Litz strand using a stranding machine. The stranding rollers are made of polytetrafluoroethylene (PTFE). PTFE rollers are hard, smooth, and offer low friction, preventing deformation and damage to the wire as it passes through the rollers. All reeling machines must be strictly synchronized with the stranding machine during stranding. The length error of each strand within the stranded Litz strand must be within 1%. The stranding machine speed should be kept to a minimum, generally not exceeding 5 meters per minute. After stranding, samples are taken for testing. Any error greater than 1% is considered defective.

[0054] Before squaring, the method further includes: wrapping the wire core with a film, wherein the wire core refers to the twisted wire bundle formed in the twisting and untwisting step.

[0055] The stranded wire bundle is wrapped in a plastic film in a clockwise direction to reduce damage to the wire bundle during squaring. The squaring die is typically made of metal. When the stranded Litz wire passes through the four corners of the square die, the outer conductors are subjected to significant pressure and friction, which can cause deformation and damage to the paint coating. However, stranded Litz wire is not a single wire or a fixed number of wires in the outer layer. Instead, as the wire is twisted, each enameled wire continuously shifts position according to the twisting sequence. As the length of the Litz wire increases, each enameled wire repeatedly appears in the outer layer according to the twist pitch. This means that each enameled wire will appear in the four corners of the metal squaring die multiple times. The longer the Litz wire, the greater the probability of this occurrence and the greater the damage. As a result, the finished Litz wire can experience numerous wire breaks and short circuits between wires due to paint damage. Before squaring, a layer of 0.05mm insulating film is first half-lapped around the twisted round Litz wire. When the round Litz wire wrapped with the insulating film passes through the squaring die, the film is always the outer layer that bears the force. The die size is adjusted to the size of the Litz wire after squaring. In this way, the enameled wire can be prevented from being damaged during the squaring process without increasing the size of the Litz wire after squaring. The film can be removed after squaring.

[0056] It also includes the Litz wire testing steps: break up the squared Litz wire, randomly select 80 single conductors to measure their withstand voltage values, randomly select 6 twisted wire harnesses to measure their withstand voltage values, randomly select 4 secondary twisted wire harnesses to measure their withstand voltage values, measure the withstand voltage values ​​of 2 composite twisted wire harnesses, and measure the withstand voltage value of 1 final wire harness.

[0057] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for processing a Litz wire coil for a wind turbine stator, characterized in that: The following steps are involved: First coating: coating the substrate surface with a first insulating layer to form a single conductor; In the first coating step, the first insulating layer is a modified polyamide-imide insulating layer, and the thickness of the modified polyamide-imide insulating layer is 0.001 mm-0.016 mm; the substrate is a round wire made of Cu-TU1; Twisting and detwisting: twisting multiple single conductors coated with the first insulation layer, and then detwisting them; In the twisting and untwisting step, a constant tension active untwisting method is adopted to keep the tension of each enameled wire bundle constant when twisting, and the twisting direction is opposite to the rotation direction of the single disk to achieve untwisting, and the twisting and untwisting operations are repeated multiple times to form a twisted wire bundle; Pressing: Pressing multiple twisted wires into a predetermined shape; Re-coating: Coating the squared wire bundle with a second insulation layer to form a Litz wire; In the re-coating step, the second insulating layer is a polyesterimide reinforced mica insulating layer, and the thickness of the polyesterimide reinforced mica insulating layer is greater than the thickness of the modified polyamideimide insulating layer; Winding: Winding Litz wire into wind turbine stator coils; It also includes the steps of Litz wire detection: break up the squared Litz wire, randomly select 80 single conductors to measure their withstand voltage values, randomly select 6 twisted wire harnesses to measure their withstand voltage values, randomly select 4 secondary twisted wire harnesses to measure their withstand voltage values, measure the withstand voltage values ​​of 2 composite twisted wire harnesses, and measure the withstand voltage value of 1 final wire harness.

2. The method for processing a Litz wire coil for a wind turbine stator according to claim 1, characterized in that: In the twisting and untwisting step, multiple single conductors are twisted and untwisted to form a twisted wire bundle, and then the multiple twisted wire bundles are twisted and untwisted again in the twisting and untwisting manner to form a secondary twisted wire bundle, and then the multiple secondary twisted wire bundles are twisted and untwisted again in the twisting and untwisting manner to form a composite twisted wire bundle.

3. The method for processing a Litz wire coil for a wind turbine stator according to claim 2, characterized in that: There are 420 single conductors, which are divided into 42 groups with 10 conductors in each group. The 10 single conductors are forward twisted and reversely detwisted to form a twisted wire harness, for a total of 42 twisted wire harnesses. The 42 twisted wire harnesses are divided into 6 groups with 7 conductors in each group. The 7 twisted wire harnesses are forward twisted and reversely detwisted to form a secondary twisted wire harness, for a total of 6 secondary twisted wire harnesses. The 6 secondary twisted wire harnesses are divided into 2 groups with 3 conductors in each group. The 3 secondary twisted wire harnesses are forward twisted and reversely detwisted to form a composite twisted wire harness, for a total of 2 composite twisted wire harnesses are obtained. The 2 composite twisted wire harnesses are finally forward twisted and reversely detwisted to form a final wire harness.

4. The method for processing a Litz wire coil for a wind turbine stator according to claim 1, characterized in that: Twisting refers to the process of twisting in which the basic conductor is twisted in a clockwise spiral structure, and detwisting refers to the process of detwisting by returning the same number of turns in the opposite direction of twisting.

5. The method for processing a Litz wire coil for a wind turbine stator according to claim 1, characterized in that: When twisting and untwisting, the tension of the twisting equipment is constant.

6. The method for processing a Litz wire coil for a wind turbine stator according to claim 1, characterized in that: During the initial insulation coating process, a multi-pass coating method is adopted.

7. The method for processing a Litz wire coil for a wind turbine stator according to claim 1, characterized in that: Before pressing, the method further includes: wrapping the wire core with a film, wherein the wire core refers to the twisted wire bundle formed in the twisting and untwisting step.

8. The method for processing a Litz wire coil for a wind turbine stator according to claim 1, characterized in that: During the second insulation coating process, a multi-pass coating method is adopted.

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