A hollow cooling high-speed motor hybrid winding

Abstract

The present invention provides a hollow-cooled hybrid winding for a high-speed motor. The hybrid winding includes N hybrid coils, each comprising an end flat wire and two in-slot hybrid wires. The end flat wire is a hollow copper flat wire; the in-slot hybrid wire comprises a hollow copper flat wire and a single-twisted Litz wire, with the single-twisted Litz wire wrapped around the hollow copper flat wire. Flow channel holes are provided at both axial ends of the hybrid coil to connect the hollow regions of the end flat wires. The hybrid winding also includes two manifolds, which are connected to external pressure equipment through pipelines. The present invention maintains the full transposition effect of traditional Litz wires, suppressing skin and proximity effects. The central portion of the in-slot hybrid wire uses a hollow copper flat wire, maintaining the characteristics of a high copper fill rate and high current-carrying capacity. The hybrid coil achieves direct contact between the cooling medium and the conductor by providing a hollow structure of the conductor and a manifold, thereby improving the heat dissipation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed motors, and in particular to a hollow-cooling high-speed motor hybrid winding. Background Art

[0002] Motor speeds are crucial for meeting the demands of modern industry, transportation, and other fields. As rotor speeds and power levels increase, motor losses (primarily winding copper loss) become increasingly significant. On the one hand, motor speeds increase the alternating frequency of the internal magnetic field, exacerbating the effects of skin and proximity effects on the AC resistance of the conductors and increasing AC copper losses in the windings. On the other hand, as motor power levels increase, DC copper losses in the armature windings also increase, posing a significant challenge to motor heat dissipation.

[0003] In recent years, flat wire and Litz wire windings have been widely used in high-power, high-speed motors. Flat wire windings offer the advantages of high slot fill factor, short end length, and low DC copper loss. However, their large current-carrying cross-sectional area makes them susceptible to skin and proximity effects, leading to uneven current distribution within the conductor, increased AC copper loss, and increased winding heat generation. Furthermore, high slot fill factors degrade the heat dissipation environment of the flat wire conductor within the slots. The tightly packed flat wire end conductors are difficult to effectively dissipate through oil spraying or forced air cooling, creating a risk of heat accumulation leading to insulation breakdown between turns. This reduces the potential for this type of winding in high-power, high-speed motors.

[0004] Litz wire is made of multiple strands of insulated thin conductors twisted together in parallel. Complete transposition ensures uniform current distribution within the thin conductors, eliminating the negative impact of circulating and eddy current losses on the winding's AC losses. However, complete transposition is difficult to achieve in engineering applications. Circulating current losses still exist within the Litz wire windings, and the insulation between the thin conductors creates significant additional heat. Furthermore, the end-forming of Litz wire windings is difficult, making it prone to breakage and inter-turn contact, increasing the risk of motor failure.

[0005] Furthermore, to reduce the risk of motor failure due to heat buildup, existing technologies typically immerse the stator core in a cooling medium. However, this approach requires an additional oil separator within the motor to separate the wet and dry parts of the stationary and rotating components, increasing the structural complexity of the motor system and reducing its reliability. Summary of the Invention

[0006] (1) Technical issues to be solved

[0007] Based on this, the present invention provides a hollow-cooled high-speed motor hybrid winding to solve the problems of severe heat generation caused by large AC copper loss of flat wire winding, long ends of Litz wire winding resulting in long axial length of the motor and difficulty in end forming, large number of insulation layers inside the wire harness resulting in difficulty in heat dissipation, large DC resistance resulting in large DC copper loss, and low reliability of the stator winding cooling structure, thereby achieving reduced copper loss and rapid cooling of the high-speed motor winding.

[0008] (2) Technical solution

[0009] In order to achieve the above object, the present invention provides a hollow-cooled high-speed motor hybrid winding, comprising: N hybrid coils, where N is a positive integer;

[0010] The hybrid coil includes an end flat wire and two in-slot hybrid wires. The in-slot hybrid wires are inserted into the stator slots of the high-speed motor. The end flat wires include a first end flat wire and a second end flat wire. The two ends of the two in-slot hybrid wires are connected to the first end flat wire and the second end flat wire respectively.

[0011] The end flat wire is a hollow copper flat wire with a hollow rectangular cross-section. The in-slot hybrid wire comprises a hollow copper flat wire and a single-twisted Litz wire, wherein multiple thin conductors of the single-twisted Litz wire are spirally twisted around a hollow copper flat wire. The hollow area of ​​the end flat wire and the hollow area of ​​the hollow copper flat wire in the in-slot hybrid wire are of the same size and are connected to each other. The single-twisted Litz wire has an integer twist pitch and is twisted only once. Its axial length is the same as the length of the stator slot.

[0012] The hybrid coil is provided with flow channel holes at both axial ends for connecting the hollow areas of the end flat wires to form the entrance and exit of the cooling flow channel; the number of flow channel holes at the outlet end is N+1, with one flow channel hole on each of the two external wiring terminals at the outlet end, and one flow channel hole on each of the remaining N-1 hybrid coils that do not contain external wiring terminals, for a total of N+1 flow channel holes; the flow channel holes at the non-outlet end are located at the position where the hybrid coil changes layers, and the number is N; the opening direction of the flow channel holes of the external wiring terminals at the outlet end of the hybrid winding is radial, and the opening direction of the flow channel holes of the hybrid coil that does not contain external wiring terminals is axial; the opening direction of the flow channel holes corresponding to the hybrid coils at the non-outlet end of the hybrid winding is all axial;

[0013] The hybrid winding further includes two collectors, namely an outlet end collector and a non-outlet end collector; the outlet end collector includes N+1 inlets and one outlet, the N+1 inlets respectively correspond to the flow channel holes at the outlet end of the hybrid winding, and the outlet of the outlet end collector is used to converge the cooling medium and then flow out; the non-outlet end collector includes one inlet and N outlets, the N outlets respectively correspond to the flow channel holes at the non-outlet end of the hybrid winding, and the inlet of the non-outlet end collector is used to allow the cooling medium to enter and then be diverted to the N outlets.

[0014] Preferably, the single-twisted litz wire and the end flat wire have the same cross-sectional outer contour dimensions.

[0015] Preferably, the single-twisted Litz wire and the conductor of the end rectangular wire are connected by resistance welding.

[0016] Preferably, the end flat wire and the hollow copper flat wire of the in-slot mixed wire are an integrated structure.

[0017] Preferably, the conductor parts of the end flat wire and the mixed wire in the slot are made of the same material, and the collecting pipe is made of a non-metallic, non-conductive material with high thermal conductivity and high strength.

[0018] Preferably, the hybrid winding formed by the N hybrid coils is in the form of a distributed stacked winding.

[0019] Preferably, it is characterized in that N=4.

[0020] Preferably, one intra-slot hybrid wire of each hybrid coil is placed in the upper layer of a stator slot, and another intra-slot hybrid wire is placed in the lower layer of another stator slot. If they are arranged according to this rule, there will be 8 layers in each stator slot, each layer is an intra-slot hybrid wire, and the layers are insulated.

[0021] (3) Beneficial effects

[0022] From the above technical solution, it can be seen that the hollow-cooled high-speed motor hybrid winding proposed by the present invention has the following beneficial effects:

[0023] 1. The present invention combines the advantages of flat wire winding and Litz wire winding. On the one hand, the single-twisted Litz wire of the in-slot hybrid line is wrapped around the outside of the hollow copper flat wire, maintaining the complete transposition effect of the traditional Litz wire, so that the current can be evenly distributed over the entire cross-section, achieving the suppression of skin effect and proximity effect, and having the characteristic of low AC loss; on the other hand, the central part of the in-slot hybrid line adopts hollow copper flat wire, still maintaining the characteristics of high copper fill rate and high current carrying capacity.

[0024] 2. The hybrid coil realizes direct contact between the cooling medium and the conductor by setting the hollow structure of the wire and the collecting pipe, which greatly improves the heat dissipation effect.

[0025] 3. When the heat dissipation requirements are met and the AC loss is suppressed, the current density of the hybrid line in the slot can be further improved, which can effectively reduce the size of the motor and improve the power-to-weight ratio of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0027] Figure 1 This is a schematic structural diagram of a hybrid coil according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic cross-sectional view of the flat wire at the end and the mixed wire in the slot according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of the structure of a single coil side of a hybrid coil according to an embodiment of the present invention;

[0030] Figure 4 This is a partial enlarged view of the connection point a between the end flat wire and the mixed wire in the slot according to an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the connection structure of the hollow copper flat wires of the end flat wires and the hybrid wires in the slots in the hybrid coil according to an embodiment of the present invention;

[0032] Figure 6 Schematic diagram comparing the thickness of the end flat wire and the hollow copper flat wire in the slot hybrid wire in the hybrid coil according to the embodiment of the present invention; the thinner one is the hollow copper flat wire in the slot hybrid wire, and the thicker one is the end flat wire;

[0033] Figure 7 Schematic diagram of twisting of single-twisted Litz wire according to an embodiment of the present invention;

[0034] Figure 8 This is a schematic structural diagram of a hybrid coil before forming according to an embodiment of the present invention;

[0035] Figure 9 A schematic diagram of a hybrid winding structure formed by four hybrid coils according to an embodiment of the present invention;

[0036] Figure 10 Schematic diagram of the spatial arrangement of the in-slot mixing wires arranged in the stator slots according to an embodiment of the present invention;

[0037] Figure 11 This is a schematic structural diagram of the flow channel hole at the outlet end of the hybrid winding according to an embodiment of the present invention;

[0038] Figure 12 This is a schematic structural diagram of the flow channel hole at the non-outlet end of the hybrid winding according to an embodiment of the present invention;

[0039] Figure 13 This is a schematic structural diagram of a collector at the outlet end of a hybrid winding according to an embodiment of the present invention;

[0040] Figure 14 This is a schematic structural diagram of a non-outlet end current collector of a hybrid winding according to an embodiment of the present invention;

[0041] Figure 15 Schematic diagram of the assembly of the outgoing-end current collector, the non-outgoing-end current collector, and the hybrid coil in the hybrid winding according to an embodiment of the present invention;

[0042] Figure 16 This is a schematic diagram of the three-dimensional structure of a stator assembly obtained by assembling the hybrid winding through distributed lap winding according to an embodiment of the present invention.

[0043] Among them: 1-first end flat wire; 2-mixed wire in the groove; 3-second end flat wire. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] The present invention provides a hollow-cooled high-speed motor hybrid winding, comprising N hybrid coils, where N is a positive integer. In this embodiment, the hybrid winding formed by the N hybrid coils is a distributed lap winding, but other armature winding configurations are also suitable, such as a distributed wave hybrid winding and a concentrated hybrid winding.

[0046] like Figure 1 As shown, the hybrid coil includes an end flat wire and two in-slot hybrid wires 2. The in-slot hybrid wires 2 are inserted into the stator slots of the high-speed motor and can cut the magnetic lines of force to generate induced electromotive force; the end flat wires include a first end flat wire 1 and a second end flat wire 3, which do not cut the magnetic lines of force and are only used as connecting wires; the two ends of the two in-slot hybrid wires 2 are respectively connected to the first end flat wire 1 and the second end flat wire 3.

[0047] The end flat wire is a hollow copper flat wire, and its cross section is a hollow rectangle, such as Figure 2 As shown in the left figure; the mixed wire 2 in the slot contains hollow copper flat wire and single-twisted Litz wire (single-layer twisted, that is, each twisted wire is a thin conductor). The single-twisted Litz wire is wrapped around the outside of the hollow copper flat wire, that is, multiple thin conductors of the single-twisted Litz wire are spirally twisted around a center wire (hollow copper flat wire). Its cross section is as shown Figure 2As shown in the right figure, this embodiment has only one layer of thin conductor outside the hollow copper flat wire, but multiple layers of thin conductors are also possible. Specifically, under the influence of the external rotor magnetic field, the back EMF generated by the single thin conductor and the hollow copper flat wire of the in-slot hybrid wire 2 are identical. This means that the hollow copper flat wire of the in-slot hybrid wire 2 has a similar effect to the central single strand of traditional Litz wire, the difference being that the central single strand is replaced with a hollow copper flat wire in this embodiment. The hollow structure of the end flat wires and the in-slot hybrid wire 2 provides a path for the fluid cooling medium, thereby cooling the windings.

[0048] On the one hand, the single-twisted Litz wire is wrapped around the outside of the hollow copper flat wire, and the in-slot hybrid wire 2 maintains the complete transposition effect of the traditional Litz wire, which can make the current inside each thin wire completely consistent, thereby suppressing the skin effect and proximity effect; on the other hand, compared with traditional copper flat wire or Litz wire, the center part of the in-slot hybrid wire 2 uses a hollow copper flat wire, which still maintains the characteristics of high copper fullness and strong thermal conductivity, and by setting up a hollow structure, direct contact between the cooling medium and the conductor is achieved, greatly improving the heat dissipation effect. When the heat dissipation requirements are met and the AC loss is suppressed, the current density of the in-slot hybrid wire 2 can be further improved, effectively reducing the volume of the motor and improving the power-to-weight ratio of the motor. Through the above settings, the in-slot hybrid wire 2 has the characteristics of high current carrying capacity and low AC loss, which can effectively improve the output performance of the motor at high speeds.

[0049] The single coil side structure of the hybrid coil is as follows Figure 3 As shown, the partial enlarged view of the connection point a between the end flat wire and the mixed wire 2 in the slot is shown in FIG. Figure 4 As shown, the cross-sectional outer contour of the single-twisted Litz wire is rectangular, and its dimensions may or may not be consistent with the cross-sectional outer contour dimensions of the end flat wire. In this embodiment, to facilitate the molding of the single-twisted Litz wire, the single-twisted Litz wire and the end flat wire have the same cross-sectional outer contour dimensions. The single-twisted Litz wire and the end flat wire conductor are connected using resistance welding. During the welding process, it is necessary to prevent damage to the insulation between the thin conductors of the single-twisted Litz wire.

[0050] In the hybrid coil, the end flat wire and the hollow copper flat wire of the hybrid wire 2 in the slot are connected as follows: Figure 5 In this embodiment, the end flat wire and the hollow copper flat wire of the in-slot hybrid wire 2 are an integrated structure, the inner contours (i.e., hollow areas) of the cross sections of the two are consistent in size and connected correspondingly, while the outer contours of the cross sections are different in size (i.e., different in thickness), as shown. Figure 6As shown, the goal is to ensure that the end flat wires can match the additional current carried by the in-slot hybrid wire 2, thereby preventing higher current density and losses in the end flat wires during steady-state operation. Furthermore, the hollow copper flat wires of the in-slot hybrid wire 2 provide a stranding "mold" for the single-twisted Litz wires. This means that the hollow copper flat wires of the in-slot hybrid wire 2 serve as a hollow support structure during the forming process of the single-twisted Litz wires. In the hybrid coil, the conductors of the end flat wires and the in-slot hybrid wires are made of the same material.

[0051] In addition, the twist pitch number (twist number) of the single-twisted Litz wire is an integer, so that the alternating magnetic fields of different thin wires are symmetrically distributed in space, the phase difference tends to be uniform, the magnetic fields cancel each other out, and the eddy current loss is reduced, ensuring that the proximity effect is almost completely suppressed. In this embodiment, the twist pitch number of the single-twisted Litz wire is 7, such as Figure 7 As shown in Figure 1. Single-twist Litz wire is twisted only once, and its axial length is the same as the length of the stator core.

[0052] like Figure 8 As shown, two single coils with the same structure are welded by laser welding, TIG welding, etc. to form the hybrid coil. During the welding process, the hollow parts of the flat wires at the ends need to be aligned to prevent blockage of the flow channel and affect the cooling effect of the winding.

[0053] In this embodiment, N=4, and the hybrid winding formed by the four hybrid coils is as follows: Figure 9 As shown. One hybrid wire 2 in each hybrid coil is placed in the upper layer of a stator slot, and another hybrid wire 2 in another stator slot is placed in the lower layer. According to this arrangement, there are 8 layers in each stator slot, each layer is a hybrid wire 2 in the slot, and the layers are insulated, as shown. Figure 10 shown.

[0054] The two axial ends of the hybrid coil (the outgoing end and the non-outgoing end) are provided with flow channel holes, such as Figure 9 As shown in part b, the flow channel hole is used to connect the hollow area of ​​the flat wire at the end to form the entrance and exit of the cooling channel. Figure 11 As shown in the figure, the two long sides are the external terminals of the hybrid winding, which are the physical interfaces for current input or output. The opening direction of the flow channel holes is radial; the opening direction of the flow channel holes of the hybrid coil without external terminals is axial. Figure 12 As shown, the opening directions of the flow channel holes corresponding to the mixing coils are all axial.

[0055] The hybrid winding also includes two current collectors (the outgoing terminal current collector and the non-outgoing terminal current collector). Figure 13As shown, it includes five inlets and one outlet. The five inlets correspond to the flow channel holes at the outlet end of the hybrid winding, and the cooling medium flows out from one outlet after converging. The non-outlet end manifold is as shown in FIG. Figure 14 As shown, it includes one inlet and four outlets. The four outlets correspond to the flow channel holes at the non-outlet end of the hybrid winding. The cooling medium enters from the inlet and is divided into four outlets. The manifold is sealed between the hybrid coil.

[0056] It can be seen that for a hybrid winding, if its number of turns is N, the number of flow channel holes at its outlet end is N+1, with one flow channel hole on each of the two external terminal blocks at the outlet end, and one flow channel hole on each of the remaining N-1 hybrid coils that do not contain external terminal blocks, for a total of N+1 flow channel holes; the flow channel holes at the non-outlet end are located at the position where the hybrid coil changes layers, and the number is N (equal to the number of turns).

[0057] Correspondingly, the current collector at the outgoing end of the hybrid winding with N turns includes N+1 inlets and one outlet, and the N+1 inlets correspond to the flow channel holes at the outgoing end of the hybrid winding respectively; the current collector at the non-outgoing end includes one inlet and N outlets, and the N outlets correspond to the flow channel holes at the non-outgoing end of the hybrid winding respectively.

[0058] In hybrid winding, the collector is made of non-metallic, non-conductive material with high thermal conductivity and high strength, and is only used to provide a path for the cooling fluid. The assembly structure of the two collectors and the hybrid coil is as follows: Figure 15 As shown, the output-side header, hybrid coil, and non-output-side header are arranged axially. These two headers are connected to external pressure equipment through piping, enabling rapid cooling of the hybrid winding. Furthermore, this cooling method only applies to the stator, a stationary component. Static sealing alone is required to isolate the cooling medium, achieving "dry-wet separation."

[0059] The stator assembly obtained by assembling the hybrid winding in a distributed stacking manner is as follows Figure 16 As shown, all collecting pipes are connected to the external cooling pipeline respectively, so that the stator armature winding (hybrid winding) can be cooled efficiently.

[0060] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A hollow cooling high-speed motor hybrid winding, characterized in that: include: N hybrid coils, where N is a positive integer; The hybrid coil includes an end flat wire and two in-slot hybrid wires. The in-slot hybrid wires are inserted into the stator slots of the high-speed motor. The end flat wires include a first end flat wire and a second end flat wire. The two ends of the two in-slot hybrid wires are connected to the first end flat wire and the second end flat wire respectively. The end flat wire is a hollow copper flat wire with a hollow rectangular cross-section. The in-slot hybrid wire comprises a hollow copper flat wire and a single-twisted Litz wire, wherein multiple thin conductors of the single-twisted Litz wire are spirally twisted around a hollow copper flat wire. The hollow area of ​​the end flat wire and the hollow area of ​​the hollow copper flat wire in the in-slot hybrid wire are of the same size and are connected to each other. The single-twisted Litz wire has an integer twist pitch and is twisted only once. Its axial length is the same as the length of the stator slot. The hybrid coil is provided with flow channel holes at both axial ends for connecting the hollow areas of the end flat wires to form the entrance and exit of the cooling flow channel; the number of flow channel holes at the outlet end is N+1, with one flow channel hole on each of the two external wiring terminals at the outlet end, and one flow channel hole on each of the remaining N-1 hybrid coils that do not contain external wiring terminals, for a total of N+1 flow channel holes; the flow channel holes at the non-outlet end are located at the position where the hybrid coil changes layers, and the number is N; the opening direction of the flow channel holes of the external wiring terminals at the outlet end of the hybrid winding is radial, and the opening direction of the flow channel holes of the hybrid coil that does not contain external wiring terminals is axial; the opening direction of the flow channel holes corresponding to the hybrid coils at the non-outlet end of the hybrid winding is all axial; The hybrid winding further includes two collectors, namely an outlet end collector and a non-outlet end collector; the outlet end collector includes N+1 inlets and one outlet, the N+1 inlets respectively correspond to the flow channel holes at the outlet end of the hybrid winding, and the outlet of the outlet end collector is used to converge the cooling medium and then flow out; the non-outlet end collector includes one inlet and N outlets, the N outlets respectively correspond to the flow channel holes at the non-outlet end of the hybrid winding, and the inlet of the non-outlet end collector is used to allow the cooling medium to enter and then be diverted to the N outlets.

2. The high-speed motor hybrid winding according to claim 1, characterized in that: The single-twisted litz wire and the end flat wire have the same cross-sectional outer contour size.

3. The high-speed motor hybrid winding according to claim 1, characterized in that: The single-twisted litz wire and the conductor of the end rectangular wire are connected by resistance welding.

4. The high-speed motor hybrid winding according to claim 1, characterized in that: The end flat wire and the hollow copper flat wire of the in-slot mixed wire are an integrated structure.

5. The high-speed motor hybrid winding according to claim 1, characterized in that: The conductor parts of the end flat wire and the mixed wire in the slot are made of the same material, and the collecting pipe is made of a non-metallic, non-conductive material with high thermal conductivity and high strength.

6. The high-speed motor hybrid winding according to claim 1, characterized in that: The hybrid winding formed by the N hybrid coils is in the form of a distributed stacked winding.

7. The high-speed motor hybrid winding according to claim 6, characterized in that: N＝4。 8. The high-speed motor hybrid winding according to claim 7, characterized in that: One intra-slot hybrid wire of each hybrid coil is placed in the upper layer of a stator slot, and the other intra-slot hybrid wire is placed in the lower layer of another stator slot. If they are arranged according to this rule, there will be 8 layers in each stator slot, each layer is an intra-slot hybrid wire, and the layers are insulated.

Images