Stator insulation method and electric machine

Abstract

The application belongs to the technical field of electric machines, and particularly relates to a stator insulation method and an electric machine, which comprises the following steps: S1, embedding a coil in a slot of a stator core; S2, packaging one end of the slot of the coil-embedded stator through a glue solution; S3, filling glue in the slot to fill the glue solution between the inner wall of the slot and the electromagnetic wire and between the electromagnetic wires, and the glue solution and the closed section jointly form a filling section after solidification; S4, dipping paint on the coil area outside the filling section; the application strengthens the weak insulation area in the stator structure, improves the insulation performance of the electric machine, and the air and holes in the filling section are less, and the insulation deterioration speed is slower. On the premise that the weight of the stator structure is not greatly increased, the heat conductivity, the partial discharge starting voltage and other performances of the insulation system of the electric machine are improved, the operation of the electric machine is more reliable, and the electric machine can be safely and reliably operated at a higher voltage.

Description

Technical Field

[0001] This invention belongs to the technical field of electric motors, specifically relating to a stator insulation method and an electric motor. Background Technology

[0002] The weakest point in the stator winding insulation is mainly located in the coil area within the stator core slots. To improve the insulation, integrity, and protection of the windings, low-voltage motors typically employ a stator-wide impregnation process during manufacturing. While this method can strengthen the weak points in the insulation to some extent, the structure obtained through impregnation inevitably contains air pockets, voids, and breaks within the stator core slots. This structure can meet design requirements for a certain period under low voltage and weak electric field conditions, but as the voltage increases, such as when the bus voltage exceeds 700V or even 800V, partial discharge inevitably occurs internally, significantly accelerating insulation degradation and reducing the reliability of motor operation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a stator insulation method and a motor that improves the thermal conductivity and partial discharge initiation voltage performance of the motor insulation system without significantly increasing the weight of the stator structure.

[0004] This invention provides a stator insulation method, which includes the following steps:

[0005] S1. The coil made of electromagnetic wire is embedded in the slot of the stator core and the coil is connected to obtain a wire-embedded stator.

[0006] S2. The channel end of the embedded stator is sealed with adhesive, so that the adhesive fills the inner wall of the channel end and the electromagnetic wire and the electromagnetic wire and electromagnetic wire to form a closed section. The plane of the end face of the channel end is located between the two ends of the closed section, or the end face of one end of the closed section is flush with the end face of the channel end. The coil area located outside the end of the channel with the closed section has a distance between its end and the closed section.

[0007] S3. With the end of the coiled stator without the closed section facing upwards, apply glue to the channel through this end, so that the glue fills the space between the inner wall of the channel and the electromagnetic wire and between the electromagnetic wires, and the glue is in contact with the closed section. The glue and the closed section together form a potting section. The plane of the end face of the channel where the glue is applied is located between the two ends of the potting section, or the end face of the channel where the glue is applied is flush with the end face of the potting section. The coil area located outside the end of the channel where the glue is applied leaves a distance between its end and the potting section.

[0008] S4. Impregnate the coil area located outside the potting section with varnish.

[0009] Furthermore, the electromagnetic wire is a corona-resistant electromagnetic wire.

[0010] Furthermore, in step S2, before sealing one end of the channel of the embedded stator with adhesive, the electromagnetic wire located at the end of the channel to be sealed is heated so that the temperature of the electromagnetic wire at that end is higher than the curing temperature of the adhesive.

[0011] Furthermore, step S3 also includes installing a potting mold on the end of the coiled stator where the closed section is not provided, and the adhesive enters the channel along the potting mold.

[0012] Furthermore, in step S3, before the adhesive cures, the embedded stator after being filled with adhesive is placed in a sealed container and vacuumed to remove bubbles.

[0013] Furthermore, if the level of the adhesive liquid is lower than the end face of the channel where the adhesive is being poured after vacuum degassing, then adhesive liquid needs to be added and vacuum degassing should be performed again to ensure that the level of the adhesive liquid is not lower than the end face of the channel where the adhesive is being poured after vacuum degassing.

[0014] Furthermore, the end faces at both ends of the channel are located between the two ends of the potting section, and the distance between any end of the potting section and the end face of the channel with the shortest distance is not less than 2mm. Moreover, the thickness of the insulation layer formed on the coil surface in the potting section area located outside the channel is greater than the thickness of the insulation layer formed on the coil surface where the varnish is applied in step S4.

[0015] Furthermore, in step S1, after the coil is embedded in the slot of the stator core, a slot wedge is installed at the opening of the slot to fix the coil.

[0016] Furthermore, step S1 also includes separating the wire welding points between the coils using a separator.

[0017] The present invention also provides an electric motor comprising a stator structure obtained by the stator insulation method described above.

[0018] The beneficial effects of this invention are that by sealing one end of the stator core's slot and then injecting adhesive into the slot through the other end, the adhesive fills the spaces between the electromagnetic wires and between the inner wall of the slot and the electromagnetic wires, forming a potting section. This strengthens the weak insulation areas in the stator structure, improving the motor's insulation performance. Simultaneously, by using varnish impregnation for non-weak insulation areas, compared to overall varnish impregnation, the potting section in this invention contains fewer air bubbles and pores, resulting in slower insulation degradation. Without significantly increasing the weight of the stator structure, it improves the thermal conductivity and partial discharge initiation voltage of the motor's insulation system, making the motor more reliable and enabling safe and reliable operation at higher voltages. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure before potting in this invention.

[0020] Figure 2 This is a schematic diagram of the structure after potting according to the present invention.

[0021] Figure 3 This is a cross-sectional view (AA) of the first embodiment of the present invention.

[0022] Figure 4 This is a cross-sectional view (AA) of the second embodiment of the present invention.

[0023] In the diagram, 1-coil; 2-encapsulation section; 3-stator core; 4-electromagnetic wire; 5-segment; 6-slot wedge; 7-impregnation section. Detailed Implementation

[0024] This invention provides a first embodiment of a stator insulation method, as shown in the attached figure. Figure 1-3 As shown, this method is applicable to loosely wound windings and specifically includes the following steps:

[0025] S1. Using electromagnetic wire 4, coil 1 is wound on a shuttle machine, maintaining consistent tension during the winding process. The coil 1, wound with electromagnetic wire 4, is then embedded in the slot of stator core 3. Slot wedges 6 are used to fix the coil 1. The coil 1 is then connected according to design requirements to obtain a wire-embedded stator. Typically, two or more phases of coil 1 are placed in a single slot; therefore, the welding points of the coil 1 within a single slot should be staggered as much as possible. If staggering is not possible, this is to prevent mutual interference. The separator 5 is specifically a thin film or composite foil. Preferably, electromagnetic wire 4 is corona-resistant electromagnetic wire, meaning the enameled insulation layer of electromagnetic wire 4 contains corona-resistant inorganic nanomaterials.

[0026] S2. Encapsulate one end of the slot of the wound stator: Fill the space between the inner wall of this end of the slot and the electromagnetic wire 4, and between the electromagnetic wires 4, to form a closed section, thus sealing this end of the slot of the wound stator and ensuring that the adhesive will not flow out along this end during subsequent injection of adhesive. The specific location of the closed section can be: the plane containing the end face of this end of the slot is located between the two ends of the closed section, that is, one end of the closed section is located inside the slot and the other end is located outside the slot; or one end face of the closed section is flush with the end face of this end of the slot, that is, the closed section is located inside or outside the slot, and one end of the closed section is flush with the end face of this end of the slot. After this end is encapsulated, a distance is left between the end of the coil 1 area located outside the end of the slot with the closed section and the closed section. In order to ensure the sealing effect of the closed section and the end insulation effect of the coiled stator, the preferred implementation method is that the plane where the end face of the channel is located is located between the two ends of the closed section, and the distance between the end face of the closed section outside the channel and the end face of the channel is not less than 2mm. The adhesive of the closed section outside the channel is filled between the electromagnetic wires 4 at the corresponding position and wrapped around the outside of the electromagnetic wires 4 at the corresponding position, so as to form an insulating layer of a certain thickness on the surface of the corresponding position area of ​​the coil 1, and the thickness of the insulating layer is not less than 1mm.

[0027] The method of filling the adhesive between the channel and the electromagnetic wire 4, and between the electromagnetic wires 4, can be done manually by using a brush to apply the adhesive or by dripping adhesive. Before applying the adhesive, the present invention also includes local or heating of the electromagnetic wire 4 located at the end of the channel to be sealed, so that the temperature of the electromagnetic wire 4 at that end is higher than the curing temperature of the adhesive, such as heating the electromagnetic wire 4 to 90-180℃. Therefore, when applying the adhesive, it can prevent the adhesive from solidifying too quickly, so that the adhesive can flow as much as possible into the gaps between the channel and the electromagnetic wire 4, and between the electromagnetic wires 4, ensuring that there are no air gaps between the electromagnetic wires 4 and between the electromagnetic wire 4 and the stator core 3.

[0028] S3. Filling the channel: With the end of the coiled stator without the closed section facing upwards, fill the channel with glue through this end, filling the channel with glue and filling the space between the inner wall of the channel and the electromagnetic wire 4, as well as between the electromagnetic wires 4. In the vertical direction, the glue at the bottom is in contact with the closed section. The glue injected in step S3 and the closed section together form the filling section 2. The plane of the end face of the channel where glue is injected is located between the two ends of the filling section 2, or the end face of the channel where glue is injected is flush with the end face of the filling section 2. And there is a distance between the end of the coil 1 area located outside the end of the channel where glue is injected and the filling section 2.

[0029] In S3, before potting, a potting mold is installed on the end of the coiled stator without a closed section. The potting mold has a hollow cavity, through which the coil 1 area located outside the channel can pass. During potting, the adhesive is poured along the cavity of the potting mold, and the adhesive flows into the channel and gradually fills the space between the inner wall of the channel and the electromagnetic wire 4, as well as between the electromagnetic wires 4. By installing the potting mold before potting, it is easier to control the liquid level of the adhesive.

[0030] In step S3, before the adhesive cures, the encapsulated stator is placed in a sealed container for vacuum degassing to reduce air bubbles in the encapsulated section 2 after curing, thereby improving the insulation performance of the encapsulated section 2. During the vacuum degassing process, the level of the adhesive liquid needs to be observed. If the level of the adhesive liquid is found to have dropped, adhesive liquid needs to be added and vacuum degassing should be performed again to ensure that the level of the adhesive liquid after vacuum degassing is not lower than the end face of the channel where the adhesive was applied, so that the end of the cured encapsulated section is at least flush with the end face of the channel where the adhesive was applied. To ensure the end insulation effect of the encapsulated stator, it is preferable that the height (spacing) between the end of the encapsulated section and the end face of the channel where the adhesive was applied is not less than 2mm. The adhesive liquid of the encapsulated section 2 located outside the channel where the adhesive was applied fills between the corresponding electromagnetic wires 4 and wraps around the outside of the corresponding electromagnetic wires 4, so as to form an insulating layer of a certain thickness on the surface of the corresponding area of ​​the coil 1, and the thickness of the insulating layer is not less than 1mm. Even after the adhesive has cured, the end faces of both ends of the channel are located between the two ends of the potting section 2, and the distance between any end of the potting section 2 and the end face of the channel with the shortest distance is not less than 2 mm. The potting section 2 located outside the channel forms an insulating layer with a thickness of not less than 1 mm on the surface of the coil 1, so that the stator end with partial discharge also has good insulation, thereby further improving the partial discharge initiation voltage of the motor. Among them, the adhesive used in S2 and S3 of this invention is an epoxy adhesive, which contains thermally conductive fillers to improve the thermal conductivity of the adhesive.

[0031] S4. Impregnate the coil 1 area outside the potting section 2 with varnish. That is, impregnate the coil 1 area located outside the slot and without the potting section 2 to form the impregnated section 7. The end face of the impregnated section 7 connects or overlaps with the end face of the potting section 2 by a certain width, so that the coil 1 area inside the potting section 2 and the coil 1 area inside the impregnated section 7 can be fixed as a whole, ensuring the insulation, integrity and protection of the winding. The impregnation method can be VPI, immersion, drip impregnation or any of these. Since the varnish used for impregnation is generally thin, an insulating layer with a thickness of 0.1-0.2 mm will be formed on the outside of the coil 1 after impregnation. The thickness of this insulating layer is less than the thickness of the insulating layer formed on the surface of the coil 1 by the potting section 2.

[0032] This invention provides a second embodiment of a stator insulation method, as shown in the attached figure. Figure 1 , 2 As shown in Figure 4, this method is applicable to flat wire windings and specifically includes the following steps:

[0033] S1. The coil 1 is wound on a forming machine using electromagnetic wire 4, maintaining consistent tension during the winding process. The coil 1 wound by electromagnetic wire 4 is then embedded in the slot of stator core 3. The welding end is widened in a process manner, and then the coil is twisted and connected according to the design requirements to obtain a wire-embedded stator. Preferably, electromagnetic wire 4 is corona-resistant electromagnetic wire, that is, the enameled insulation layer of electromagnetic wire 4 contains inorganic nanomaterials that are resistant to corona.

[0034] Steps S2-S4 in this embodiment are the same as steps S2-S4 in embodiment one.

[0035] The present invention also provides an electric motor, which includes a stator structure obtained by the stator insulation method of the present invention.

[0036] This invention seals one end of the channel of the stator core 3 and then fills the channel with glue through the other end, filling the spaces between the electromagnetic wires 4 and between the inner wall of the channel and the electromagnetic wires 4 with glue to form a potting section 2. This strengthens the weak insulation areas in the stator structure, improving the motor's insulation performance. Simultaneously, for non-weak insulation areas (i.e., the coil 1 area outside the channel), an impregnation method is used. Compared to overall impregnation, the potting section 2 in this invention contains fewer air bubbles and pores, resulting in slower insulation degradation. Furthermore, this invention improves the thermal conductivity and partial discharge initiation voltage of the motor insulation system without significantly increasing the weight of the stator structure, making the motor more reliable and enabling safe and reliable operation at higher voltages, thereby enhancing the market competitiveness of new energy vehicle motors.

Claims

1. A method for stator insulation, characterized in that, The method includes the following steps: S1. The coil (1) made of electromagnetic wire (4) is embedded in the slot of the stator core (3), and the coil (1) is connected to obtain a wire-embedded stator. S2. The channel end of the embedded stator is sealed with adhesive, so that the adhesive fills the space between the inner wall of the channel end and the electromagnetic wire (4) and between the electromagnetic wires (4) to form a closed section. The plane of the end face of the channel end is located between the two ends of the closed section, or the end face of one end of the closed section is flush with the end face of the channel end. The coil (1) area located outside the end of the channel with the closed section has a distance between its end and the closed section. S3. Make the end of the coiled stator without the closed section facing upward, and fill the channel with glue through this end, so that the glue fills the inner wall of the channel and between the electromagnetic wire (4) and between the electromagnetic wire (4) and the electromagnetic wire (4), and the glue is in contact with the closed section. The glue and the closed section together form the potting section (2). The plane of the end face of the channel where the glue is filled is located between the two ends of the potting section (2), or the end face of the channel where the glue is filled is flush with the end face of the potting section (2). The coil (1) area located outside the end of the channel where the glue is filled has a distance between its end and the potting section (2). S4. Impregnate the coil (1) area located outside the potting section (2).

2. The stator insulation method as described in claim 1, characterized in that, The electromagnetic wire (4) is a corona-resistant electromagnetic wire.

3. The stator insulation method as described in claim 1, characterized in that, In step S2, before sealing one end of the channel of the embedded stator with adhesive, the electromagnetic wire (4) located at the end of the channel to be sealed is heated so that the temperature of the electromagnetic wire (4) at that end is higher than the curing temperature of the adhesive.

4. The stator insulation method as described in claim 1, characterized in that, In step S3, a potting mold is installed on the end of the coiled stator where the closed section is not provided, and the adhesive enters the channel along the potting mold.

5. The stator insulation method as described in claim 4, characterized in that, In step S3, before the adhesive cures, the embedded stator after being filled with adhesive is placed in a sealed container and vacuumed to remove bubbles.

6. The stator insulation method as described in claim 5, characterized in that, After vacuum degassing, if the glue level is lower than the end face of the channel where glue was applied, glue needs to be added and vacuum degassing performed again to ensure that the glue level is not lower than the end face of the channel where glue was applied after vacuum degassing.

7. The stator insulation method according to any one of claims 1-6, characterized in that, The end faces at both ends of the channel are located between the two ends of the potting section (2). The distance between any end of the potting section (2) and the end face of the channel with the shortest distance is not less than 2mm. The thickness of the insulation layer formed on the surface of the coil (1) in the potting section (2) area located outside the channel is greater than the thickness of the insulation layer formed on the surface of the coil (1) where the varnish was applied in step S4.

8. The stator insulation method according to any one of claims 1-6, characterized in that, In step S1, after the coil (1) is embedded in the slot of the stator core (3), a slot wedge (6) is installed at the opening of the slot to fix the coil (1).

9. The stator insulation method as described in claim 8, characterized in that, Step S1 also includes separating the wire welding parts between the coils (1) by using a separator (5).

10. An electric motor, characterized in that, The motor includes a stator structure obtained by the stator insulation method as described in any one of claims 1-9.

Images