Motor stator and motor

Abstract

The invention provides a motor stator and a motor. The motor stator comprises the iron core and the winding which are assembled together. The iron core is formed with a plurality of slots distributed at intervals in a circumferential direction, each slot having a radial opening. The winding is attached to the iron core and includes a first linear conductor and a second linear conductor inserted through the slots in the axial direction. In a cross section perpendicular to the axial direction, the cross-sectional shape of the first linear conductor is rectangular, the cross-sectional shape of the second linear conductor is circular, and the second linear conductor is disposed closer to the opening than the first linear conductor. Therefore, the motor stator and the motor comprising the motor stator can greatly improve the skin effect of the conductor of the winding.

Description

Technical Field

[0001] The present application relates to the field of motors, and particularly to a motor stator and a motor including the motor stator. Background Art

[0002] Currently, motors are widely used in pure electric vehicles and hybrid vehicles as power sources to drive the vehicles. A motor generally includes a motor stator and a motor rotor capable of rotating relative to the motor stator. The motor stator includes an iron core and windings assembled together. In existing motor stators, in order to improve the filling rate of the straight slots of the iron core, flat single-wire conductors with a rectangular cross-sectional shape are usually inserted into the straight slots of the iron core and fixedly installed on the iron core. These flat single-wire conductors form a predetermined electrical circuit as needed to constitute the windings. However, such flat single-wire conductors have the disadvantages of high cost and strong skin effect when the motor is in a high-speed state.

[0003] Therefore, those skilled in the art have adopted winding schemes with different structures to overcome the above disadvantages. For example, in the Chinese invention patent application with publication number CN 109088490 A and title "Stator Assembly with Uneven Conductors", it is disclosed that in the stator slots of a motor stator, flat conductors in the form of single wires with a rectangular cross-sectional shape are arranged in different layers in the radial direction, and the conductors closer to the opening of the stator slot are smaller in size in the radial direction, that is, flatter. In this scheme, since the cross-sectional size of the flat conductors is still relatively large, the skin effect is still strong, and the improvement amplitude is limited. In the Chinese invention patent with bulletin number CN 109075624 B and title "Common Laminated Component for Accommodating Multiple Conductor Geometries in a Motor", in different stator cores of a motor stator, windings are respectively formed by using conductors in the form of single wires with a circular cross-sectional shape and conductors in the form of single wires with a rectangular cross-sectional shape. In this scheme, although the cost is saved compared with the scheme of forming windings entirely by using conductors in the form of single wires with a rectangular cross-sectional shape, the improvement effect on the skin effect is limited.

[0004] It can be seen that the scheme of using different conductors mixedly installed to form windings in the motor stator of the prior art has a small effect on improving the skin effect. Summary of the Invention

[0005] In order to overcome or at least mitigate the deficiencies of the above prior art, an object of the present application is to provide a motor stator that can significantly reduce the skin effect of the conductors of the windings. Another object of the present application is to provide a motor including the above motor stator, which can improve the performance of the motor.

[0006] In order to achieve the above invention objects, the following technical solutions are adopted in the present application.

[0007] The present application provides a motor stator as follows, having an axial direction, a radial direction, and a circumferential direction. The motor stator includes:

[0008] A core, which is formed with a plurality of slots spaced apart in the circumferential direction, and the slots have openings opening towards the radially inner side or the radially outer side; and

[0009] A winding, which is installed on the core and includes a first linear conductor and a second linear conductor inserted axially through the slots. In a cross-section perpendicular to the axial direction, the cross-sectional shape of the first linear conductor is rectangular and the cross-sectional shape of the second linear conductor is circular, and the second linear conductor is arranged at a position closer to the opening than the first linear conductor.

[0010] In an alternative embodiment, in the cross-section, the cross-sectional area of the second linear conductor is less than 1 / 2 of the cross-sectional area of the first linear conductor.

[0011] In another alternative embodiment, the diameter of the circle is less than 1 mm.

[0012] In another alternative embodiment, the first linear conductors are electrically connected to each other to form a first electrical circuit, and the second linear conductors are electrically connected to each other to form a second electrical circuit.

[0013] In another alternative embodiment, the first electrical circuit and the second electrical circuit have the same topological structure.

[0014] In another alternative embodiment, the first electrical circuit and the second electrical circuit are connected in parallel with each other.

[0015] In another alternative embodiment, the winding is provided with a connection joint in the second electrical circuit.

[0016] The connection joint has a wire bundling portion and a connection portion. A plurality of the second linear conductors are bundled together by the wire bundling portion.

[0017] The connection portion is electrically connected to the connection portions of other connection joints, or the connection portion is electrically connected to the first linear conductor.

[0018] In another alternative embodiment, in each of the slots, the width direction of each first linear conductor is consistent with the width direction of the slot, and the second linear conductor is divided into one or more wire bundles, and the wire bundles and the first linear conductor are arranged in layers in the radial direction, and all the wire bundles are located on the side of the first linear conductor closer to the opening.

[0019] In another alternative solution, let the back electromotive force E1 of the first electrical circuit be E1 = 2.22fN1Φ1kw1 and the back electromotive force E2 of the second electrical circuit be E2 = 2.22fN2Φ2kw2, where f is the electrical frequency, N is the number of series conductors per phase winding, Φ is the magnetic flux, kw is the winding coefficient, and the parameters with subscript 1 correspond to the first linear conductor, and the parameters with subscript 2 correspond to the second linear conductor.

[0020] When E1 = E2 and the number of slots is Q, the number of the first linear conductors in each slot is N1×3 / Q and the number of wire harnesses is N2×3 / Q.

[0021] This application also provides a motor as follows, including the motor stator described in any one of the above technical solutions.

[0022] By adopting the above technical solution, this application provides a motor stator. In the above motor stator, it includes an iron core and a winding assembled together. The iron core is formed with a plurality of slots that are circumferentially spaced apart, and each slot has an opening that opens towards the radially inner side or the radially outer side. The winding is installed on the iron core and includes a first linear conductor and a second linear conductor that are axially inserted through the slots. In a cross-section perpendicular to the axial direction, the cross-sectional shape of the first linear conductor is rectangular (including a substantially rectangular shape) and the cross-sectional shape of the second linear conductor is circular, and the second linear conductor is arranged at a position closer to the opening than the first linear conductor. In this way, a linear conductor with a rectangular cross-sectional shape and a linear conductor with a circular cross-sectional shape are mixed in the slots of the iron core. Therefore, compared with a motor stator that completely uses linear conductors with a circular cross-sectional shape, the motor stator of this application can increase the filling rate (or slot fullness rate) of the slots of the iron core, thereby reducing the resistance of the winding. Moreover, all the linear conductors with a circular cross-sectional shape are arranged at positions close to the openings of the slots in the iron core. Therefore, compared with a motor stator that completely uses linear conductors with a rectangular cross-sectional shape and a motor stator in which different linear conductors are mixed in other modes (such as a scheme in which circular conductors and rectangular conductors are alternately arranged radially), the motor stator of this application can significantly improve the skin effect of the conductors of the winding.

[0023] Furthermore, this application also provides a motor including the above motor stator. Due to the adoption of the motor stator according to this application, the performance of the motor is improved. Description of the Drawings

[0024] Figure 1A is a schematic cross-sectional view showing a motor stator according to an embodiment of this application, in which the hatching is omitted.

[0025] Figure 1B shows Figure 1AAn enlarged schematic view of a partial structure of the iron core of the motor stator, showing the structure of a slot of the iron core and its internal components.

[0026] Figures 2A to 2C It is used to illustrate Figure 1A A schematic diagram of the circuit topology of the winding of the motor stator in

[0027] Figure 3A It shows Figure 1A An enlarged schematic view of a partial structure of the winding of the motor stator in , showing an assembly of a plurality of second linear conductors and a first connection joint.

[0028] Figure 3B It shows Figure 1A An enlarged schematic view of a partial structure of the winding of the motor stator in , showing a structure in which an assembly of a plurality of second linear conductors and a second connection joint is electrically connected to a first linear conductor.

[0029] Figure 4 It is used to illustrate Figure 1A A curve graph for explaining the performance of the motor stator in . The abscissa in the graph represents the electrical frequency of the winding (unit: Hz), and the ordinate in the graph represents the resistance of the winding (relative value).

[0030] Figure 5 An enlarged schematic view of a partial structure of the iron core of the motor stator according to a variant example of an embodiment of the present application, showing the structure of a slot of the iron core and its internal components.

[0031] Explanation of reference numerals

[0032] 1 Iron core; 1c Slot; 11 Yoke; 12 Tooth

[0033] 2 Winding; 21 First linear conductor; 22 Second linear conductor; 23 First connection joint; 231 First bundle part; 232 First connection part; 232h Connection hole; 24 Second connection joint; 241 Second bundle part; 242 Second connection part

[0034] 3 Slot wedge

[0035] 4 Insulating paper

[0036] UB1 First U-phase sub-winding; VB1 First V-phase sub-winding; WB1 First W-phase sub-winding

[0037] UB2 Second U-phase sub-winding; VB2 Second V-phase sub-winding; WB2 Second W-phase sub-winding

[0038] R Radial; C Circumferential Detailed description of the invention

[0039] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, rather than to exhaust all feasible ways of the present application, nor to limit the scope of the present application.

[0040] In the present application, unless otherwise specified, "axial direction", "radial direction", and "circumferential direction" respectively refer to the axial direction, radial direction, and circumferential direction of the motor stator (iron core).

[0041] In the present application, unless otherwise specified, the cross-section refers to a cross-section perpendicular to the axial direction of the motor stator.

[0042] The motor stator according to an embodiment of the present application will be described below with reference to the accompanying drawings of the specification.

[0043] As Figure 1A and Figure 1B shown, the motor stator according to an embodiment of the present application includes an iron core 1, a winding 2, a slot wedge 3, and an insulating paper 4 assembled together. The winding 2 is installed on the iron core 1. The slot wedge 3 is used to limit the part of the winding 2 located in the slot 1c of the iron core 1. The insulating paper 4 is arranged between the iron core 1 and the winding 2 to improve the insulation performance.

[0044] In this embodiment, the iron core 1 can be formed into a laminated body by laminating silicon steel sheets in the axial direction A. As Figure 1A and Figure 1B shown, the iron core 1 includes a yoke portion 11 and a plurality of tooth portions 12. The yoke portion 11 extends continuously in the circumferential direction C for a full circle. The plurality of tooth portions 12 project from the yoke portion 11 toward the radially inner side. The plurality of tooth portions 12 are arranged at intervals in the circumferential direction C, so that a plurality of slots 1c evenly distributed at intervals in the circumferential direction C are defined by the plurality of tooth portions 12. Specifically, a swallowtail portion for installing the slot wedge 3 is provided at the radially inner end of the tooth portion 12. Ignoring the dimensional changes caused by this swallowtail portion, the slot 1c is configured to have a constant width during the process of extending from the radially inner end toward the radially outer end, thereby forming a so-called straight slot structure. The cross-sectional shape of the slot 1c is integrally formed into a rectangular shape. In addition, both axial ends of the slot 1c are open toward the outside, and the radially outer end of the slot 1c is closed and the radially inner end is open.

[0045] In this embodiment, as Figure 1A and Figure 1B shown, the winding 2 includes a plurality of first linear conductors 21, a plurality of second linear conductors 22, and a first connection joint 23 and a second connection joint 24.

[0046] As Figure 1A and Figure 1BAs shown, each first linear conductor 21 is a flat single wire with a rectangular cross-sectional shape. In each slot 1c, the width direction of each first linear conductor 21 is the same as the width direction of the slot 1c. Further, each second linear conductor 22 is a single wire with a circular (perfect circle) cross-sectional shape, the diameter of which can be less than 1 mm and the cross-sectional area of the second linear conductor 22 is significantly less than the cross-sectional area of the first linear conductor 21. Here, as an example, the cross-sectional area of the second linear conductor 22 can be less than 1 / 2 of the cross-sectional area of the first linear conductor 21, and can even be less than 1 / 10 of the cross-sectional area of the first linear conductor 21. In addition, in each slot 1c, the second linear conductor 22 is arranged at a position closer to the opening than the first linear conductor 21. The filling rate of the slot 1c of the winding 2 is increased by the first linear conductor 21, and the skin effect of the conductors of the winding 2 can be improved by the cross-sectional shape, cross-sectional size and arrangement position of the second linear conductor 22.

[0047] As Figure 2A shown, the electrical connection of a plurality of first linear conductors 21 to each other can realize a first electrical circuit with a Y-shaped topological structure. In the first electrical circuit, it includes a first U-phase sub-winding UB1, a first V-phase sub-winding VB1, and a first W-phase sub-winding WB1. One ends of these three sub-windings UB1, VB1, and WB1 are electrically connected to each other, and the other ends of these three sub-windings UB1, VB1, and WB1 are used for electrical connection to an external three-phase power supply. As Figure 2B shown, the electrical connection of a plurality of second linear conductors 22 to each other realizes a second electrical circuit with a Y-shaped circuit topological structure. In the second electrical circuit, it includes a second U-phase sub-winding UB2, a second V-phase sub-winding VB2, and a second W-phase sub-winding WB2. One ends of these three sub-windings UB2, VB2, and WB2 are electrically connected to each other, and the other ends of these three sub-windings UB2, VB2, and WB2 are used for electrical connection to an external three-phase power supply. In this way, the first electrical circuit and the second electrical circuit have the same topological structure, and the first electrical circuit and the second electrical circuit are connected in parallel with each other. Thus, the winding 2 constitutes an electrical circuit as Figure 2C shown. In the electrical circuit of the winding 2, one ends of the first U-phase sub-winding UB1, the first V-phase sub-winding VB1, and the first W-phase sub-winding WB1 are all electrically connected to one ends of the second U-phase sub-winding UB2, the second V-phase sub-winding VB2, and the second W-phase sub-winding WB2. The other end of the first U-phase sub-winding UB1 is electrically connected to the other end of the second U-phase sub-winding UB2, the other end of the first V-phase sub-winding VB1 is electrically connected to the other end of the second V-phase sub-winding VB2, and the other end of the first W-phase sub-winding WB1 is electrically connected to the other end of the second W-phase sub-winding WB2.

[0048] To implement the above electrical circuit, the first linear conductor 21 can be configured as a hairpin unit. The hairpin unit includes a first insertion portion, a second insertion portion, and a connection portion formed integrally. The first insertion portion and the second insertion portion of the same hairpin unit can be inserted into different slots 1c. After that, the hairpin units can be electrically connected together by welding. Further, in the slots 1c of the iron core 1, a plurality of second linear conductors 22 are divided into a plurality of wire harnesses. As shown in Figure 1A and Figure 1B , the plurality of wire harnesses can be arranged in layers in the radial direction R with respect to the plurality of first linear conductors 21. Both ends of each wire harness can be provided with a first connection joint 23 as shown in Figure 3A . The first connection joint 23 is made of a conductive material and includes a first wire bundle portion 231 and a first connection portion 232 formed integrally. The first wire bundle portion 231 bundles together a plurality of second linear conductors 22 divided into the same wire harness. The first connection portion 232 extends from the first wire bundle portion 231 in a direction away from the wire harness, and a connection hole 232h is further formed in the first connection portion 232. In this way, different wire harnesses can be electrically connected through the first connection portions 232 of their respective first connection joints 23, for example, by means of a flexible conductor passing through the connection hole 232h. In fact, at least a part of the plurality of second linear conductors 22 divided into the same wire harness can be bundled together by means of an outer insulating layer. In addition, in order to enable the sub-windings UB2, VB2, WB2 of the second electrical circuit to achieve the circuit topology as shown in Figure 2C with the sub-windings UB1, VB1, WB1 of the first electrical circuit, the other ends of the sub-windings UB2, VB2, WB2 of the second electrical circuit are provided with a second connection joint 24 as shown in Figure 3B . The second connection joint 24 is made of a conductive material and includes a second wire bundle portion 241 and a second connection portion 242 formed integrally. The second wire bundle portion 241 bundles together a plurality of second linear conductors 22 divided into the same wire harness. The second connection portion 242 extends from the second wire bundle portion 241 in a direction away from the wire harness. In this way, the wire bundle portions of the second linear conductors 22 can be welded together with the first linear conductors 21 as the power connection parts of the first electrical circuit through the second connection joint 24 to achieve electrical connection.

[0049] In this embodiment, as shown in Figure 1A and Figure 1B , a slot wedge 3 is provided at the dovetail structure of the tooth portion 12 located at the opening of the slot 1c of the iron core 1 for limiting the first linear conductor 21 and the second linear conductor 22 in the radial direction R. In addition, in the slot 1c of the iron core 1, insulating paper 4 is further arranged between the first linear conductor 21 and the second linear conductor 22 and the wall of the slot 1c for improving the insulation performance of the motor stator. Of course, the arrangement position of the insulating paper 4 is not limited thereto.

[0050] The present application also provides a motor including the above-mentioned motor stator. This motor has all the technical effects of the motor stator of the present application, thereby being able to improve the performance of the motor. It can be understood that the solution of the present application can be applied to motors with an outer stator and inner rotor layout, and can also be applied to motors with an outer rotor and inner stator layout.

[0051] The following combines Figure 4 and Table 1 to illustrate the beneficial effects of a motor including a motor stator according to an embodiment of the present application.

[0052] As Figure 4 shown, the motor stator of the motor in Comparative Example 1 includes a winding formed entirely of conductors with a rectangular cross-sectional shape, and the motor stator of the motor in Comparative Example 2 includes a winding formed entirely of conductors with a circular cross-sectional shape. The motor stator of the motor in the embodiment is the motor stator described in the above embodiments. For Comparative Example 1, due to the skin effect, the resistance of the winding increases from 1 p.u (relative value) to 4 p.u. Among them, the resistance of Comparative Example 1 (all flat wire windings) when the motor frequency is close to 0 is set as 1 p.u (reference value). For Comparative Example 2, due to the lower slot fill factor and almost negligible skin effect, the resistance of the winding remains basically constant at 1.8 p.u. For the embodiment of the present application, the resistance of winding 2 increases from 1.4 p.u to a maximum of 1.75 p.u (full speed state). Further, when an eight-pole motor is typically in a working condition of 8000 rpm and a current frequency of 533.33 Hz, the resistances of the windings in Comparative Example 1, Comparative Example 2, and winding 2 of the embodiment are 1.76 p.u, 1.8 p.u, and 1.49 p.u respectively. In other words, compared with Comparative Example 1 and Comparative Example 2, the motor of the embodiment of the present application can reduce the copper loss by 15.3% and 17.2% respectively.

[0053] Regarding the endurance test standards for new energy vehicles implemented in various countries and regions, for the specified extreme working conditions (8000 rpm and 20 Nm), as shown in Table 1, the iron loss and copper loss of the motor in Comparative Example 1 are approximately 800 W and 200 W respectively, and thus the efficiency is 94.37% when mechanical losses are ignored. The iron loss and copper loss of the motor in Comparative Example 2 are approximately 800 W and 204.5 W respectively, and thus the efficiency is 94.34% when mechanical losses are ignored. The iron loss and copper loss of the motor in this embodiment are approximately 800 W and 169.3 W respectively, and thus the efficiency is 94.53% when mechanical losses are ignored. Therefore, compared with Comparative Example 1 and Comparative Example 2, the performance of the motor of the embodiment of the present application has been improved.

[0054] Table 1

[0055] Operating condition (8000 rpm and 20 Nm) Copper loss Iron loss Efficiency Comparative Example 1 200W 800W 94.37％ Comparative Example 2 204.5W 800W 94.34％ Example 169.3W 800W 94.53％

[0056] It should be understood that the above embodiments are merely exemplary and are not intended to limit the present application. Those skilled in the art can make various modifications and changes to the above embodiments under the teaching of the present application without departing from the scope of the present application. The following is a supplementary description of the technical solutions of the present application.

[0057] i. In the present application, the number of layers of the wire harnesses of the first linear conductor 21 and the second linear conductor 22 provided in one slot 1c of the iron core 1 is not limited and can be adjusted according to needs. In the above embodiments, as Figure 1B shown, three layers of the first linear conductors 21 are provided. In a variant of the above embodiments, as Figure 5 shown, two layers of the first linear conductors 21 can be provided. Additionally, in one slot 1c, multiple first linear conductors 21 can be divided into one or any other number of wire harnesses.

[0058] The number of layers of the wire harnesses of the first linear conductor 21 and the second linear conductor 22 provided in each slot 1c can be calculated by the following method. Specifically, let the back electromotive force of the first electrical circuit E1 = 2.22fN1Φ1kw1 and the back electromotive force of the second electrical circuit E2 = 2.22fN2Φ2kw2, where f is the electrical frequency, N is the number of series conductors per phase winding, Φ is the magnetic flux, kw is the winding coefficient, and the parameters with subscript 1 correspond to the first linear conductor 21, and the parameters with subscript 2 correspond to the second linear conductor 22. When E1 = E2 and the number of slots 1c is Q, the number of the first linear conductors 21 in each slot 1c is N1×3 / Q and the number of wire harnesses formed by the second linear conductors is N2×3 / Q.

[0059] ii. In the present application, the topological structures of the first electrical circuit and the second electrical circuit are not limited to the Y-shaped topological structure described in the above embodiments. In an alternative solution, the topological structures of the first electrical circuit and the second electrical circuit can adopt a triangular topological structure. In other alternative solutions, the topological structures of the first electrical circuit and the second electrical circuit can be different. In other alternative solutions, the first electrical circuit and the second electrical circuit can be connected in series with each other.

[0060] Moreover, one or more electrical circuits can be formed by using the first linear conductor 21, and one or more electrical circuits can be formed by using the second linear conductor 22.

Claims

1. A motor stator having an axial direction, a radial direction (R) and a circumferential direction (C), characterized in that, The motor stator includes: A core (1) formed with a plurality of slots (1c) spaced apart circumferentially (C), the slots (1c) having openings that open towards the radially inner or outer side; and A winding (2) mounted on the core (1) and including a first linear conductor (21) and a second linear conductor (22) inserted axially through the slots (1c). In a cross-section perpendicular to the axial direction, the cross-sectional shape of the first linear conductor (21) is rectangular and the cross-sectional shape of the second linear conductor (22) is circular, and the second linear conductor (22) is arranged at a position closer to the opening than the first linear conductor (21).

2. The motor stator according to claim 1, characterized in that, In the cross-section, the cross-sectional area of the second linear conductor (22) is less than 1 / 2 of the cross-sectional area of the first linear conductor (21).

3. The stator of an electric machine according to claim 1, characterized in that, The diameter of the circle is less than 1 mm.

4. The motor stator according to any one of claims 1 to 3, characterized in that The first linear conductors (21) are electrically connected to each other to form a first electrical circuit, and the second linear conductors (22) are electrically connected to each other to form a second electrical circuit.

5. The stator of the electric machine according to claim 4, characterized in that, The first electrical circuit and the second electrical circuit have the same topological structure.

6. The stator of the motor according to claim 4, characterized in that The first electrical circuit and the second electrical circuit are connected in parallel with each other.

7. The stator of an electric machine according to claim 6, characterized in that, The winding (2) is provided with connection joints (23, 24) in the second electrical circuit, The connection joints (23, 24) have bundling portions (231, 241) and connection portions (232, 242), and a plurality of the second linear conductors (22) are bundled together by the bundling portions (231, 241), The connection portion (232) is electrically connected to the connection portion (232) of other connection joints (23), or the connection portion (242) is electrically connected to the first linear conductor (21).

8. The stator of an electric machine according to claim 6, characterized in that, In each of the slots (1c), the width direction of each first linear conductor (21) is the same as the width direction of the slot (1c), and the second linear conductor (22) is divided into one or more wire bundles, and the wire bundles and the first linear conductors (21) are arranged in layers in the radial direction (R), and all the wire bundles are located on the side of the first linear conductors (21) closer to the opening.

9. The motor stator according to claim 8, wherein Let the back electromotive force of the first electrical circuit E1 = 2.22fN1Φ1kw1 and the back electromotive force of the second electrical circuit E2 = 2.22fN2Φ2kw2, where f is the electrical frequency, N is the number of series conductors per phase winding, Φ is the magnetic flux, kw is the winding coefficient, and the parameters with subscript 1 correspond to the first linear conductor (21), and the parameters with subscript 2 correspond to the second linear conductor (22), In the case of E1 = E2 and the number of slots (1c) being Q, the number of the first linear conductors (21) in each slot (1c) is N1×3 / Q and the number of the wire bundles is N2×3 / Q.

10. A motor, characterized in that, Including the motor stator according to any one of claims 1 to 9.

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