An electromagnetic flat wire, its stator coil, and a motor stator

Abstract

This invention discloses an electromagnetic flat wire, comprising a copper conductor and inter-turn insulation. The copper conductor consists of a solid bare copper inner conductor and an outer conductor with an inner hole, the inner conductor fitting the inner hole. The outer conductor consists of an upper lobe and a lower lobe, which are pressed onto the inner conductor. The mating surfaces of the upper and lower lobes are connected as a whole by welding or bonding. The invention also discloses a stator coil and a motor stator obtained by winding the wire. By configuring a large-section electromagnetic flat wire into an inner and outer layer structure, with the inner layer structure allowing axial free expansion and contraction relative to the outer layer, the bending process difficulty is reduced. There is no insulation between the inner and outer layers, only inter-turn insulation in the outer layer, which improves slot fill factor, thereby reducing copper loss and increasing efficiency.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, and particularly relates to an electromagnetic flat wire suitable for high voltage and low frequency, as well as a stator coil and motor stator using the electromagnetic flat wire. Background Technology

[0002] For high-voltage motors using electromagnetic flat wire, the coils are generally formed using an expansion forming machine. When the cross-section of a single conductor is large (exceeding 40mm), 2 ) when Figure 1 As shown, when the conductor is twisted at the nose end, the difference between the inner and outer diameters is large, causing the inner side of the conductor to shrink and the outer side to stretch. This results in high stress on the conductor, which leads to insufficient torque in the forming machine, incomplete forming, and easy damage to the external insulation.

[0003] To accommodate the bulging process, a large cross-section conductor typically needs to be split into multiple flat conductors along the conventional slot height direction. Figure 2 and Figure 3 As shown, each split flat conductor has inter-turn insulation at this point, but the inter-turn insulation between the split conductors is ineffective and occupies copper space, reducing the slot fill factor. Especially for high-voltage motors, the inter-turn insulation thickness is about 0.5mm. Even if a whole conductor that was originally 5mm thick is split into two, the thickness of the two copper conductors is 2.25mm, resulting in a 10% loss of copper conductor cross-section.

[0004] To reduce the decrease in slot fill factor caused by conductor splitting, when there are many split conductors, only a very thin layer of interstrand insulation (such as 0.15mm) is usually left on the split conductors. Then, after multiple split conductors are combined, inter-turn insulation is manually added. This increases the manufacturing time and is only applicable when the number of split conductors is ≥3.

[0005] When only two conductors need to be split, the common practice is to machine-insulate each split conductor between turns, but this means sacrificing slot fill factor without increasing working hours. Summary of the Invention

[0006] One of the objectives of this invention is to address the problem of low slot fill factor and poor manufacturability caused by splitting into thin conductors for high-voltage and low-frequency motors, which are in demand for large-section electromagnetic flat wires. The invention proposes an electromagnetic flat wire with a stretchable inner and outer layer. The inner conductor is stretchable, the outer conductor is easily deformable, and insulation is only provided on the outside of the outer conductor, thus balancing slot fill factor and manufacturability.

[0007] The technical solution adopted by this invention to solve its technical problem is: an electromagnetic flat wire, comprising a copper conductor and inter-turn insulation wrapped around the outside of the copper conductor. The copper conductor is composed of an inner conductor and an outer conductor. The inner conductor is a solid bare copper conductor structure, and the outer conductor has a rectangular cross-section with an inner hole. The inner conductor is adapted to the inner hole. The inner conductor and the outer conductor are independent of each other. During the coil bending and forming process, the inner conductor can freely expand and contract along the axial direction. The outer conductor is composed of an upper lobe and a lower lobe. The upper lobe and the lower lobe are pressed onto the inner conductor. The splicing surfaces between the upper lobe and the lower lobe are connected into a whole by welding or bonding.

[0008] The electromagnetic flat wire has rounded corners at the four corners of its rectangular cross-section.

[0009] The electromagnetic flat wire described above has a small gap fit between its inner and outer conductors.

[0010] The electromagnetic flat wire has an outer conductor upper lobe and an outer conductor lower lobe with a "[" shaped cross section.

[0011] The second objective of this invention is to provide a stator coil obtained by winding the above-mentioned electromagnetic flat wire.

[0012] The third objective of this invention is to provide a motor stator, which is composed of a stator core and a stator coil as described in claim 2, wherein the slot-insulated portion is composed of slot wedges, copper conductors, inter-turn insulation, main insulation, and interlayer spacers.

[0013] The beneficial effects of this invention are as follows: By setting the large cross-section electromagnetic flat wire into an inner and outer layer structure, the inner layer structure can freely expand and contract axially relative to the outer layer, which reduces the difficulty of the bending process. There is no insulation between the inner and outer layers, and there is only inter-turn insulation in the outer layer, which improves the slot fill factor and balances the slot fill factor and processability, thereby reducing the copper loss of the motor and improving efficiency. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a traditional electromagnetic flat wire, a single large-section conductor, that does not split.

[0015] Figure 2 This is a diagram of the stator slot embedding of a traditional electromagnetic flat wire double-turn motor.

[0016] Figure 3 This is a diagram of the embedded wires in the stator slots of a traditional electromagnetic flat wire-wound motor.

[0017] Figure 4 This is a cross-sectional view of the inner and outer layers of the large-section electromagnetic flat wire of the present invention;

[0018] Figure 5 This is a schematic diagram of the outer conductor structure of the present invention;

[0019] Figure 6 This is a diagram showing the embedded wires in the stator slots of a motor with parallel-wound magnetic flat wires according to the present invention.

[0020] The labels for each figure are as follows: 1—slot wedge, 2—copper conductor, 3—inter-turn insulation, 4—main insulation, 5—interlayer spacer, 2.1—inner conductor, 2.2—outer conductor, 2.2.1—upper lobe of outer conductor, 2.2.2—lower lobe of outer conductor. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in conjunction with the accompanying drawings and examples to enable those skilled in the art to better understand the present invention. Example 1

[0022] Reference Figure 4 As shown, the present invention discloses an electromagnetic flat wire, comprising a copper conductor 2 and inter-turn insulation 3 wrapped around the outside of the copper conductor 2. The copper conductor 2 is composed of an inner conductor 2.1 and an outer conductor 2.2. The inner conductor 2.1 is a solid bare copper conductor structure, and the outer conductor 2.2 has a rectangular cross-section with an inner hole. The inner conductor 2.1 is adapted to the inner hole. The inner conductor 2.1 and the outer conductor 2.2 are independent of each other. During the coil bending and forming process, the inner conductor 2.1 is allowed to freely expand and contract along the axial direction. No insulation is provided between the inner conductor 2.1 and the outer conductor 2.2.

[0023] Reference Figure 5 As shown, the outer conductor 2.2 consists of an upper outer conductor lobe 2.2.1 and a lower outer conductor lobe 2.2.2. First, the inner conductor 2.1, the upper outer conductor lobe 2.2.1, and the lower outer conductor lobe 2.2.2 are manufactured separately. Then, the upper outer conductor lobe 2.2.1 and the lower outer conductor lobe 2.2.2 are pressed onto the inner conductor 2.1. The splicing surfaces between the upper outer conductor lobe 2.2.1 and the lower outer conductor lobe 2.2.2 are connected into a whole by welding or bonding, thereby obtaining a novel electromagnetic flat wire.

[0024] The outer conductor 2.2 has a rectangular structure on the outside with rounded corners on its four sides. The inner conductor 2.1 has a rectangular hole on the inside. The inner conductor 2.1 is a solid copper conductor with a rectangular structure. The inner conductor 2.1 and the rectangular hole on the inside of the outer conductor 2.2 are fitted with a small clearance in terms of size. The outer conductor 2.1 is wrapped with insulation 3 by mechanical equipment, while no insulation is set between the inner conductor 2.1 and the outer conductor 2.2.

[0025] The outer conductor 2.2 of this invention is further divided into an upper outer conductor lobe 2.2.1 and a lower outer conductor lobe 2.2.2 with a "[" shaped cross section. The upper outer conductor lobe 2.2.1, the lower outer conductor lobe 2.2.2, and the inner conductor 2.1 are first manufactured by extrusion molding. The upper outer conductor lobe 2.2.1 and the lower outer conductor lobe 2.2.2 are then pressed onto the inner conductor 2.1. Finally, the splicing surfaces between the upper outer conductor lobe 2.2.1 and the lower outer conductor lobe 2.2.2 are formed into a whole by welding or bonding. However, it is necessary to ensure that the inner and outer conductors are not connected. The inner conductor 2.1 can freely expand and contract relative to the outer conductor 2.2. Example 2

[0026] The present invention discloses a stator coil, which is obtained by winding the above-mentioned electromagnetic flat wire. Example 3

[0027] The present invention discloses a motor stator, which is composed of a stator core and a stator coil as described in claim 2. The slot-embedded part is composed of a slot wedge 1, a copper conductor 2, inter-turn insulation 3, main insulation 4, and interlayer spacer 5, etc. Figure 6 This is a schematic diagram of a stator slot using the double-layer electromagnetic flat wire of the present invention.

[0028] This invention is applied to the field of high-voltage, low-frequency motors. Low frequency means that a larger cross-section (greater penetration depth) is allowed from the perspective of AC loss. However, if the cross-section of the electromagnetic wire is too large during the coil forming process, the stress will be high during bending, the processability will be poor, and it will easily cause damage to the inter-turn insulation 3. Therefore, multiple electromagnetic flat wires are generally used in parallel winding in the slot height direction to adapt to the processability. High voltage means that the inter-turn insulation 3 is thicker, and the insulation between these parallel winding conductors is not necessary, which reduces the slot fill factor.

[0029] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. An electromagnetic flat wire, comprising a copper conductor (2) and inter-turn insulation (3) wrapped around the outside of the copper conductor (2), characterized in that: The copper conductor (2) is composed of an inner conductor (2.1) and an outer conductor (2.2). The inner conductor (2.1) and the outer conductor (2.2) are in a gap fit. The inner conductor (2.1) is a solid bare copper conductor structure. The outer conductor (2.2) has a rectangular cross-section with an inner hole. The inner conductor (2.1) is adapted to the inner hole. The outer conductor (2.2) is composed of an upper outer conductor lobe (2.2.1) and a lower outer conductor lobe (2.2.2). The splicing surfaces of the upper outer conductor lobe (2.2.1) and the lower outer conductor lobe (2.2.2) pressed onto the inner conductor (2.1) are welded or bonded together.

2. The electromagnetic flat wire according to claim 1, characterized in that, The rectangular cross-section of the outer conductor (2.2) is provided with transition rounded corners.

3. An electromagnetic flat wire according to claim 1 or 2, characterized in that, The outer conductor upper lobe (2.2.1) and outer conductor lower lobe (2.2.2) have a "[" shaped cross section.

4. A stator coil, characterized in that, It is obtained by winding the electromagnetic flat wire as described in claim 1.

5. A motor stator, characterized in that, It consists of a stator core and a stator coil as described in claim 4, wherein the slot-inserted portion consists of a slot wedge (1), a copper conductor (2), inter-turn insulation (3), main insulation (4), and interlayer spacer (5).

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