An AC composite conductor for high-speed motor windings

Abstract

This invention discloses an AC composite conductor for high-speed motor windings, relating to the field of motor technology. It can improve motor power density while also suppressing the magnetic field in the event of a short-circuit fault in the winding. The conductor includes an outer flat copper wire, flat copper wire insulation, an inner round wire, round wire insulation, and end connectors. The flat copper wire has a hollow structure, and the ends of the two flat copper wires are connected by end connectors. The flat copper wire is divided into inner and outer lobes, with the enamel coating retained on the contact surface between the two lobes. The round wire is embedded within the flat copper wire. The flat copper wire and the round wire respectively form a flat copper wire winding and a round wire winding, each connected to two independent converters. The converters are completely electrically isolated, and the current in the two parts of the conductor can be controlled independently. When a short-circuit fault occurs in any one set of conductors, the other set of windings can be controlled to suppress the magnetic field, thus preventing further deterioration of the short-circuit fault.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to an AC composite conductor for high-speed motor windings. Background Technology

[0002] Electric motors are the core components of electromechanical energy conversion. Due to their high energy conversion efficiency and flexible control, they are widely used in industrial production, aerospace, transportation, and home appliances. In emerging industries such as new energy vehicles and multi-electric aircraft, replacing traditional energy utilization methods with high-speed motors has become an important development direction. High-speed motors have higher power density and lighter, smaller passive components in motor systems, which is an important measure to further improve the electromechanical energy conversion efficiency of motor systems and reduce energy waste.

[0003] Compared to other motors, high-speed motors have high-frequency alternating current flowing through their AC windings. This high-frequency alternating current induces eddy currents in the slot leakage magnetic field within the conductors. The presence of these induced eddy currents results in uneven current distribution across the conductor's cross-section; that is, the current density decreases significantly in certain regions of the conductor, leading to a substantial reduction in the conductor's effective cross-sectional area. As the frequency increases, this reduction in effective cross-sectional area becomes increasingly pronounced; this phenomenon is commonly referred to as the AC effect of the windings.

[0004] To address the AC effects of high-speed motor windings, fine round wires of suitable diameter or more complex Litz wires can be used as winding conductors. However, due to the numerous gaps between the insulation paper on the inner wall of the motor slot and the wires, as well as between the wires themselves, using these types of wires significantly reduces the conductive area within the motor tooth space. Furthermore, the presence of these gaps worsens heat dissipation between the wires and the iron core within the slot, further limiting the current-carrying capacity of the wires.

[0005] Another approach uses hollow copper wires to form the motor windings, with a cooling medium circulating through the internal cavity to avoid the effects of AC interference. However, this design sacrifices a significant amount of slot space, requiring a larger motor size to compensate for the loss of conductivity while maintaining a fixed power demand, thus hindering further increases in power density. Furthermore, high-speed motors require a rapid reduction in the excitation magnetic field when a short-circuit fault occurs. If the excitation adjustment is not timely or cannot be directly adjusted, the short-circuit fault will worsen, affecting not only the motor's power output but also jeopardizing the operational safety of the motor system.

[0006] Therefore, how to improve the power density of the motor while also suppressing the magnetic field when a short circuit fault occurs in the winding has become a direction that needs further improvement for high-speed motor windings. Summary of the Invention

[0007] Embodiments of the present invention provide an AC composite conductor for high-speed motor windings, which can improve the power density of the motor and suppress the magnetic field when the windings experience a short circuit fault.

[0008] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0009] An AC composite conductor for high-speed motor windings includes: an outer flat copper wire (1), flat copper wire insulation (2), an inner round wire (3), and an inner round wire insulation (6); the outer flat copper wire (1) is a hollow structure, and both the inner and outer surfaces of the outer flat copper wire (1) are coated with insulating varnish. The end of the outer flat copper wire (1) is connected to an end connector, and the types of the end connectors include: an end connector without a top opening (4) and an end connector with a top opening (5); the inner round wire (3) is embedded in the outer flat copper wire (1).

[0010] The outer flat copper wire (1) includes two parts: inner lobe (11) and inner lobe (10); the contact end face of the inner lobe (11) and inner lobe (10) is the inner and outer lobe Z-shaped step end face (14), and the contact end face of the inner lobe (11) and inner lobe (10) is also coated with insulating varnish.

[0011] When the AC composite conductor is applied to an inner rotor motor with radial flux, the interface between the inner lobe (11) and the inner lobe (10) of the outer flat copper wire (1) is distributed radially along the outer flat copper wire (1); the cross-sectional area of ​​the inner lobe (11) of the outer flat copper wire (1) near the slot opening is smaller than the cross-sectional area of ​​the inner lobe (11) of the outer flat copper wire (1) near the bottom of the slot; the cross-sectional area of ​​the inner lobe (10) of the outer flat copper wire (1) near the slot opening is smaller than the cross-sectional area of ​​the inner lobe (10) of the outer flat copper wire (1) near the bottom of the slot.

[0012] The numerical relationship between the inner lobe width (13) and the outer lobe width (12) of the flat copper wire conforms to... Among them, B n1 B n2 The magnetic flux density represents the direction of the indicator line perpendicular to the width of the inner lobe (13) and the width of the outer lobe (12) of the flat copper wire, respectively. 12 Indicates the inner lobe width value of the flat copper wire, l 13 This indicates the width of the outer lobe of the flat copper wire.

[0013] The maximum thickness of each boundary of the external flat copper wire (1) is determined by the operating frequency, and the maximum thickness is not greater than the skin depth corresponding to the fundamental frequency of the motor, wherein the skin depth is... Where ρ is the resistivity of copper, f is the fundamental frequency of the alternating current inside the copper conductor, and μ is the permeability of copper.

[0014] If the inner round wire (3) and the outer flat copper wire (1) adopt the same winding installation type, the end connector adopts the end connector without top opening (4), and the inner round wire (3) and the outer flat copper wire (1) are insulated from each other; if the inner round wire (3) and the outer flat copper wire (1) adopt different winding installation types, the end connector adopts the end connector with top opening (5), wherein the bend of the end connector with top opening (5) is provided with a through hole for the inner round wire (3) to extend.

[0015] Insulating varnish is filled into the gaps between the outer flat copper wire (1) and the insulating paper (7) in the groove, the gaps between the inner round wire (3) and the outer flat copper wire (1), and the gaps between the inner round wire (3) using a vacuum impregnation process; insulating varnish is retained on the contact surface of the step between the two lobes of the outer flat copper wire (1). The contact surface of the step between the two lobes of the flat copper wire should retain insulating varnish to reduce the path of induced eddy current flow and suppress the influence of AC effect.

[0016] An internal cavity (9) is provided in the bundle of inner round wires (3), and the internal cavity (9) is filled with an insulating cooling medium. A hole (15) is provided on the outer surface of the outer flat copper wire (1).

[0017] The AC composite wire is wound on the winding of the high-speed motor (17), wherein the outer flat copper wire (1) and the inner round wire (3) are wound to form an outer flat copper wire winding (18) and an inner round wire winding (19), respectively; the outer flat copper wire winding (18) is connected to converter I (20), and the inner round wire winding (19) is connected to converter II (21), and converter I (20) and converter II (21) are electrically isolated; converter I (20) includes: a supporting capacitor C1, a first switch S1 to a sixth switch S6, and a first diode D1 to a sixth diode D6 connected in reverse parallel with the first switch S1 to the sixth switch S6, respectively; converter III (16) includes: a supporting capacitor C2, a seventh switch S7 to a twelfth switch S6, and a seventh switch S7 to a twelfth switch S6, respectively connected in reverse parallel with the first switch S1 to the sixth switch S6, respectively. 12 and respectively with the seventh switch S7 to the twelfth switch S 12 The seventh diode D7 to the twelfth diode D are connected in reverse parallel. 12 .

[0018] The AC composite conductor for high-speed motor windings provided in this invention allows the motor windings to maintain a large effective conductive area even when high-frequency current is applied. The composite conductor ensures sufficient contact with the iron core, enhancing the heat dissipation capacity of the motor windings. Under short-circuit fault conditions, the motor using the composite conductor can suppress short-circuit current and reduce the risk of fault escalation through the coordinated control of the two sets of windings. When an open-circuit fault occurs in one set of windings, the application of the composite conductor also enables the motor to maintain a certain power output capability, further enhancing the motor's fault tolerance. Thus, it achieves both increased motor power density and magnetic field suppression in the event of a short-circuit fault in the windings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the AC composite conductor provided in an embodiment of the present invention;

[0021] Figure 2 , 3 4 is a schematic cross-sectional view of the AC composite conductor provided in the embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the opening method on the AC composite conductor provided in an embodiment of the present invention;

[0023] Figure 6 A schematic diagram of a possible end connector provided in an embodiment of the present invention;

[0024] Figure 7 A schematic diagram of an AC composite conductor wound on a high-speed motor winding, provided in an embodiment of the present invention;

[0025] The labels in the attached diagram represent: 1-Outer flat copper wire, 2-Flat copper wire insulation layer, 3-Inner round wire, 4-End connector without top opening, 5-End connector with top opening, 6-Inner round wire insulation layer, 7-Insulating paper inside the slot, 8-Iron core, 9-Internal cavity of the conductor, 10-Outer lobe of flat copper wire, 11-Inner lobe of flat copper wire, 12-Width of outer lobe of flat copper wire, 13-Width of inner lobe of flat copper wire, 14-Z-shaped step end face of inner and outer lobe, 15-Opening of flat copper wire, 16-Contact end face of end connector, 17-High-speed motor, 18-Outer flat wire winding, 19-Inner round wire winding, 20-Bidirectional power converter I, 21-Bidirectional power converter II. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Embodiments of the present invention will be described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in the specification of the present invention means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0027] This invention provides an AC composite conductor for high-speed motor windings, such as... Figures 1-6 As shown, it includes:

[0028] Outer flat copper wire (1), flat copper wire insulation (2), inner round wire (3), and inner round wire insulation (6); among which, such as Figure 1 As shown, the flat copper wire has a hollow structure, with the inner round wire (3) embedded in the outer flat copper wire (1).

[0029] Specifically, the round wire is embedded between two flat copper wires, and the round wire itself has an insulating varnish film. After the processes of embedding, fastening, and stator winding are completed, the motor stator is impregnated with varnish, and the gap between the round wire and the outer flat wire will be filled with insulating varnish, making the overall winding structure reliable in strength and with excellent thermal conductivity.

[0030] The outer flat copper wire (1) is a hollow structure. Both the inner and outer surfaces of the outer flat copper wire (1) are coated with insulating varnish. The end of the outer flat copper wire (1) is connected to an end connector. The types of end connectors include: end connectors without top openings (4) and end connectors with top openings (5).

[0031] In this embodiment, the outer flat copper wire (1) includes two parts: inner lobe (11) and inner lobe (10); the contact end face of the inner lobe (11) and the inner lobe (10) is the inner and outer lobe Z-shaped step end face (14), and the contact end face of the inner lobe (11) and the inner lobe (10) is also coated with insulating varnish to ensure good insulation between the inner and outer lobes.

[0032] Among them, such as Figure 2 , 4 As shown, the hollow flat copper wire is divided into inner and outer lobes. The cross-sectional areas of the two lobes can be unequal, and the ratio of their cross-sectional areas should be determined based on the magnetic environment of the wire. The side with a larger linking magnetic flux should have a smaller cross-sectional area, while the other side should have a larger cross-sectional area. Simultaneously, the maximum thickness of each boundary of the hollow flat copper wire should also be determined based on the operating frequency, and the maximum thickness should not exceed the skin depth corresponding to the fundamental frequency of the current flowing through it. For example: designed as... Figure 2 The composite conductor shown has an inner circular wire 3 embedded inside an outer flat copper wire 1. The outer flat copper wire 1 is divided into two parts, with the direction closest to the bottom of the slot of the iron core 8 as the inside, namely the outer flat copper wire lobe 10 and the inner flat copper wire lobe 11.

[0033] Simultaneously, a Z-shaped step is provided on the contact surface between the two lobes to ensure reliable fixation between the two flat wire lobes after the round wire is embedded. The contact surface of the step between the two lobes of the flat copper wire should retain insulating varnish to ensure good insulation between the inner and outer lobes, thereby reducing the path of induced eddy current flow and suppressing the influence of AC effects. For example: Figure 4 The inner and outer contact surfaces shown are in a "Z" shape. The insulating varnish on the Z-shaped step end face 14 does not need to be removed to ensure good insulation between the inner and outer lobes.

[0034] Furthermore, such as Figure 4 As shown, a series of holes are made on the thinner side of the flat copper wire to ensure sufficient impregnation of the conductor. To ensure that the voids inside the outer flat copper wire (1) are fully filled with insulating varnish, a series of flat copper wire openings 15 are made on the thinner side of the outer flat copper wire. For example: Figure 5 As shown, in order to ensure that the internal gaps of the outer flat copper wire 1 can be fully filled by the insulating varnish, a hole (15) is provided on the outer surface of the outer flat copper wire (1), specifically on the thinner side of the outer flat copper wire (1). The size of the hole 15 can be adjusted according to factors such as the tightness of the internal conductor filling and the air pressure injected during the vacuum impregnation process.

[0035] In this embodiment, when the AC composite conductor is applied to an inner rotor motor with radial magnetic flux, the interface between the inner lobe (11) and the inner lobe (10) of the outer flat copper wire (1) is distributed radially along the outer flat copper wire (1). For example... Figure 4 The cross-sectional area of ​​the inner petal (11) of the outer flat copper wire (1) near the slot opening and the slot bottom shown is smaller than the cross-sectional area of ​​the inner petal (11) of the outer flat copper wire (1) near the slot bottom; the cross-sectional area of ​​the inner petal (10) of the outer flat copper wire (1) near the slot opening is smaller than the cross-sectional area of ​​the inner petal (10) of the outer flat copper wire (1) near the slot bottom.

[0036] Specifically, for an internal rotor motor with radial flux, the interface between the two flat copper wires is radially distributed, and the flat copper wire lobe near the slot opening has a smaller cross-sectional area than the flat copper wire lobe near the slot bottom. If the conductor is used in a motor with a different topology, the ratio of the cross-sectional area of ​​the inner lobe to that of the outer lobe should be determined based on the magnetic environment of the two flat copper wires; specifically, the cross-sectional area of ​​the flat copper wire lobe on the side with larger linkage flux should be smaller. During final conduction, the current on the cross-sectional area of ​​each flat copper wire lobe should be uniformly distributed. Furthermore, to ensure that the gaps between the outer flat copper wire 1 and the slot insulating paper 7, between the inner round wire 3 and the outer flat copper wire 1, and between the inner round wire 3 can be fully filled with insulating varnish, a vacuum impregnation process is preferred.

[0037] Furthermore, the flat copper wire portion of the composite conductor comprises inner and outer lobes, the cross-sectional areas of which may be unequal. The ratio of the cross-sectional areas of the two lobes should be determined based on the magnetic environment in which the conductor is located. The side with a larger linking magnetic flux should have a smaller cross-sectional area, i.e., a smaller width. The other side should have a larger flat copper wire cross-section, i.e., a larger width. Figure 4 Taking the slotted flat copper wire as an example, the numerical relationship between the inner lobe width (13) and the outer lobe width (12) of the flat copper wire conforms to the following expression:

[0038] Among them, B n1 B n2 Let l represent the magnetic flux density in the direction of the indicator line perpendicular to the width of the inner lobe (13) and the width of the outer lobe (12) of the flat copper wire, respectively. The integral paths on both sides of the equation are the lengths of the indicator lines for the widths of the inner lobe (13) and the outer lobe (12) of the flat copper wire. 12 Indicates the inner lobe width value of the flat copper wire, l 13 This indicates the width of the outer lobe of the flat copper wire.

[0039] The maximum thickness of each boundary of the outer flat copper wire (1) is determined by the operating frequency, and the maximum thickness is not greater than the skin depth corresponding to the fundamental frequency of the motor. The skin depth is... Where ρ is the resistivity of copper, f is the fundamental frequency of the alternating current inside the copper conductor, and μ is the permeability of copper.

[0040] In this embodiment, the inner round wire (3) and the outer flat copper wire (1) can adopt the same winding installation type. The end connector adopts the end connector without top opening (4), and the inner round wire (3) and the outer flat copper wire (1) are mutually insulated. There is no need to adopt the end connector with top opening (5). At the wire outlet, attention should be paid to the insulation of the inner and outer windings.

[0041] If the inner round wire (3) and the outer flat copper wire (1) adopt different winding installation types, the end connector adopts an end connector (5) with a top opening. The bend of the end connector (5) with a top opening is provided with a through hole for the inner round wire (3) to extend, so as to ensure that different types of winding installation of round wire and flat wire can be realized.

[0042] For example: Figure 6 As shown, the end connector 4 without a top opening can be designed with a stepped shape on its contact surface 16, which connects to the straight section of the winding. The end face of the straight section of the winding can be set as a raised step, and the insulating varnish on all sides of the step should be stripped. After the end connector is assembled, a low-melting-point welding material is applied to the stepped surface, and the corresponding position of the contact surface 16 of the end connector is locally heated to ensure a reliable connection at the end. To avoid damage to the internal round wire insulation layer 6 during heating, a sleeve made of heat-insulating material can be pre-wound around the round wire at the corresponding position of the contact surface 16 of the end connector.

[0043] In this embodiment, two types of end connectors are designed. One type of connector does not have a top opening and mates with the protruding end face of the straight section of the conductor. After the insulation is stripped, the mating surfaces can achieve a good electrical connection through welding or other means. Care must be taken to protect the insulation layer of the round wire during welding. The other type of connector has a top opening through which the round wire can be routed. The combined use of the two types of connectors allows for differentiation in the winding forms of round wire windings and flat wire windings, making the winding connection of the motor more flexible.

[0044] Furthermore, in this embodiment, an insulating varnish is filled in the gaps between the outer flat copper wire (1) and the insulating paper (7) in the groove, the gaps between the inner round wire (3) and the outer flat copper wire (1), and the gaps between the inner round wire (3) using a vacuum impregnation process. To ensure that the gaps between the outer flat copper wire (1) and the insulating paper (7), the inner round wire (3) and the outer flat copper wire (1), and the inner round wire (3) are fully filled with insulating varnish, a vacuum impregnation process is preferred. Insulating varnish is retained on the contact surface of the step between the two lobes of the outer flat copper wire (1). The contact surface of the step between the two lobes of the flat copper wire should retain insulating varnish to reduce the path of induced eddy current flow and suppress the influence of AC effects.

[0045] Furthermore, an internal cavity (9) is provided within the bundle of inner circular wires (3), and the internal cavity (9) is filled with an insulating cooling medium. For example... Figure 3 As shown, when the space inside the motor slots is sufficient and the frequency of the alternating current in the conductors is high enough, the slot fill factor of the internal round wire can be appropriately reduced. This is achieved by filling the center of the round wire with a thin-shell hollow tube containing hot melt adhesive before impregnation. The tube wall material can be the same polyester fiber as the motor winding. After impregnation, the hot melt adhesive can be liquefied by heating the stator to 110°C, forming an internal cavity 9 in the conductor. After the conductor is energized, a cooling medium can be directly supplied to the internal cavity 9 to cool the winding, enhancing its heat dissipation capacity and providing the possibility of further increasing the conductor's current-carrying capacity. In practical applications, since the round wire is embedded between two flat copper wires, the round wire itself has an insulating varnish film. After the processes of embedding, fastening, and stator unwinding are completed, the motor stator undergoes impregnation, and the gap between the round wire and the outer flat wire is filled with insulating varnish. The overall structure of the winding is reliable in strength and has excellent thermal conductivity.

[0046] In practical applications, the AC composite wire can be wound on the winding of a high-speed motor (17), wherein the outer flat copper wire (1) and the inner round wire (3) are wound to form an outer flat copper wire winding (18) and an inner round wire winding (19), respectively.

[0047] The external flat copper wire winding (18) is connected to converter I (20), and the internal round wire winding (19) is connected to converter II (21). Converter I (20) and converter II (21) are electrically isolated.

[0048] The converter I (20) includes: a support capacitor C1, a first switch S1 to a sixth switch S6, and a first diode D1 to a sixth diode D6 that are connected in reverse parallel with the first switch S1 to the sixth switch S6 respectively;

[0049] Converter III (16) includes: a supporting capacitor C2, and seventh switch S7 to twelfth switch S1. 12 and respectively with the seventh switch S7 to the twelfth switch S 12 The seventh diode D7 to the twelfth diode D are connected in reverse parallel. 12 .

[0050] For example: Figure 7 As shown, in the high-speed motor 17 using composite wire windings, the outer flat copper wire 1 and the inner round wire 3 of the composite wire form two sets of windings, namely the outer flat wire winding 18 and the inner round wire winding 19. The outer flat wire winding 18 is connected to converter I 20, and the inner round wire winding 19 is connected to converter II 21. The two converters are completely electrically isolated to avoid circulating current. Figure 7In converter I 20, there are switching transistors S1 to S6, anti-parallel diodes D1 to D6, and supporting capacitor C1; converter II 21 is similar, including switching transistors S7 to S8. 12 Reverse parallel diodes D7 to D 12 And supporting capacitor C2. Typically, the external flat wire winding 18 can be divided into three phases. In the circuit, R and L represent the resistance and inductance of a certain phase winding, respectively, and E is the induced electromotive force of a certain phase resistance. In the subscripts at the bottom right, the letters a, b, and c indicate the phase to which each component belongs, the number 1 represents the external flat wire winding 18, and the number 2 represents the internal round wire winding 19. For example, R a1 E represents the phase resistance of the external flat wire winding 18. c2 This represents the c-phase induced electromotive force of the internal circular wire winding 19.

[0051] When a short-circuit fault occurs in any set of windings, if the excitation magnetic field cannot be adjusted in time or cannot be adjusted at all, the current of another set of normal windings can be controlled to generate a demagnetizing magnetic field in the normal windings, weakening or even canceling the effect of the main magnetic field, so as to avoid the continuous induction of short-circuit current in the short-circuit windings and further aggravation of the fault.

[0052] When an open-circuit fault occurs in any set of winding circuits, the corresponding converter can be controlled to completely disconnect the faulty winding, and the normal winding will continue to run, which gives the motor a certain fault tolerance capability. Figure 7 The wiring configuration shown for a high-speed motor with composite conductor windings is only one option. By making reasonable use of end connectors with openings, other forms of motor winding connection can also be supported.

[0053] The AC composite conductor designed in this embodiment is suitable for high-speed motor windings. This conductor includes an outer flat copper wire, flat copper wire insulation, an inner round wire, round wire insulation, and end connectors. The flat copper wire has a hollow structure, coated with insulating varnish both inside and out. The ends of the two flat copper wires are connected by end connectors. The flat copper wire is divided into inner and outer lobes, the cross-sectional areas of which can be unequal, and the varnish on the contact surface between the lobes is retained. The round wire is embedded within the flat copper wire and can extend through a hole pre-drilled in the end connector with a top opening. The flat copper wire and round wire form the flat copper wire winding and the round wire winding, respectively, each connected to two independent converters. The converters are completely electrically isolated, and the current in the two conductors can be controlled independently. When a short-circuit fault occurs in either conductor winding, the other winding can be controlled to suppress the magnetic field, preventing further deterioration of the short-circuit fault. The two windings can be completely in phase or staggered by a certain angle as needed, forming a multi-phase or double three-phase winding structure. When an open-circuit fault occurs in one winding, the converter can be controlled to disconnect the faulty winding, while the non-faulty windings continue to operate, further improving the motor's fault tolerance. The composite conductor of this invention can effectively enhance the current-carrying capacity of motor windings at high frequencies and increase the heat dissipation capacity of the motor windings, which is beneficial for further improving the power density, efficiency, and operational reliability of high-speed motors.

[0054] Specifically, the AC composite conductor designed in this embodiment has the following advantages compared with the existing high-speed motor conductors: (1) The current carrying capacity of the high-speed motor winding is greatly improved, and the motor volume can be effectively reduced for the same power requirement, and the power density of the motor is further improved; (2) The contact area between the slot winding and the insulating paper in the iron core is increased, which can enhance the heat conduction capacity of the slot winding. Under the same heat dissipation conditions, the maximum allowable current density of the conductor is increased, which is conducive to improving the power density and overload capacity of the motor; (3) The two sets of windings are independently controlled, which is conducive to achieving magnetic field suppression during faults.

[0055] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An AC composite conductor for high-speed motor windings, characterized in that, include: Outer flat copper wire (1), flat copper wire insulation (2), inner round wire (3) and inner round wire insulation (6); The outer flat copper wire (1) is a hollow structure. Both the inner and outer surfaces of the outer flat copper wire (1) are coated with insulating varnish. The end of the outer flat copper wire (1) is connected to an end connector. The types of end connectors include: end connectors without top openings (4) and end connectors with top openings (5). The inner circular line (3) is embedded in the outer flat copper wire (1); The outer flat copper wire (1) includes two parts: inner lobe (11) and inner lobe (10); The contact surfaces of the inner lobe (11) and the inner lobe (10) are Z-shaped stepped end surfaces (14) of the inner and outer lobes, and the contact surfaces of the inner lobe (11) and the inner lobe (10) are also coated with insulating varnish. When the AC composite conductor is applied to an inner rotor motor with radial magnetic flux, the interface between the inner lobe (11) and the inner lobe (10) of the outer flat copper wire (1) is distributed radially along the outer flat copper wire (1). The cross-sectional area of ​​the inner lobe (11) of the outer flat copper wire (1) near the slot opening is smaller than the cross-sectional area of ​​the inner lobe (11) of the outer flat copper wire (1) near the bottom of the slot; the cross-sectional area of ​​the inner lobe (10) of the outer flat copper wire (1) near the slot opening is smaller than the cross-sectional area of ​​the inner lobe (10) of the outer flat copper wire (1) near the bottom of the slot. The numerical relationship between the inner lobe width (13) and the outer lobe width (12) of the flat copper wire conforms to... Among them, B n1 B n2 The magnetic flux density represents the direction of the indicator line perpendicular to the width of the inner lobe (13) and the width of the outer lobe (12) of the flat copper wire, respectively. 12 Indicates the inner lobe width value of the flat copper wire, l 13 This indicates the width of the outer lobe of the flat copper wire.

2. The AC composite conductor for high-speed motor windings according to claim 1, characterized in that, The maximum thickness of each boundary of the external flat copper wire (1) is determined by the operating frequency, and the maximum thickness is not greater than the skin depth corresponding to the fundamental frequency of the motor, wherein the skin depth is... ,in, The resistivity of copper, This is the fundamental frequency of the alternating current inside the copper conductor. Let be the magnetic permeability of copper.

3. The AC composite conductor for high-speed motor windings according to claim 1, characterized in that, If the inner round wire (3) and the outer flat copper wire (1) adopt the same winding installation type, the end connector adopts the end connector (4) without top opening, and the inner round wire (3) and the outer flat copper wire (1) are mutually insulated; If the inner round wire (3) and the outer flat copper wire (1) adopt different winding installation methods, the end connector adopts an end connector (5) with a top opening, wherein the bend of the end connector (5) with a top opening is provided with a through hole for the inner round wire (3) to extend.

4. The AC composite conductor for high-speed motor windings according to claim 1 or 3, characterized in that, Insulating varnish is filled into the gaps between the outer flat copper wire (1) and the inner insulating paper (7), the gaps between the inner round wire (3) and the outer flat copper wire (1), and the gaps between the inner round wire (3) through the vacuum impregnation process. Insulating varnish is retained on the contact surface of the step between the two lobes of the outer flat copper wire (1); The contact surface of the step between the two lobes of the flat copper wire should retain insulating varnish to reduce the path of induced eddy current flow and suppress the influence of AC effect.

5. The AC composite conductor for high-speed motor windings according to claim 1, characterized in that, An internal cavity (9) is provided in the bundle of the inner circular wires (3), and the internal cavity (9) is filled with an insulating cooling medium.

6. The AC composite conductor for high-speed motor windings according to claim 1, characterized in that, A hole (15) is provided on the outer surface of the outer flat copper wire (1).

7. The AC composite conductor for high-speed motor windings according to claim 1, characterized in that, The AC composite wire is wound on the winding of the high-speed motor (17), wherein the outer flat copper wire (1) and the inner round wire (3) are wound to form the outer flat copper wire winding (18) and the inner round wire winding (19), respectively. The external flat copper wire winding (18) is connected to converter I (20), and the internal round wire winding (19) is connected to converter II (21). Converter I (20) and converter II (21) are electrically isolated. The converter I (20) includes: a support capacitor C1, a first switch S1 to a sixth switch S6, and a first diode D1 to a sixth diode D6 that are connected in reverse parallel with the first switch S1 to the sixth switch S6 respectively; The inverter III (16) includes a support capacitor C2, seventh to twelfth switching transistors S7 to S12 12 , and seventh to tenth diodes D7 to D 12 10 connected in anti-parallel with the seventh to twelfth switching transistors S7 to S 12 12, respectively.

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