Stator assembly and motor

Abstract

The present disclosure provides a stator assembly, comprising: a stator core, comprising an annular stator yoke and a plurality of stator teeth connected to the stator yoke; and windings, each winding comprising a first coil group and a second coil group connected in parallel, one first coil and one second coil being wound on each stator tooth, the first coil group comprising at least one first coil, the second coil group comprising at least one second coil, and the first coil of the first coil group and the second coil of the second coil group of each winding being wound on a same stator tooth. The first coils are wound around the stator teeth, and the second coils are wound around the peripheries of the first coils. The first coils comprise a conductive first material, and the second coils comprise a conductive second material. The resistivity of the first material is lower than that of the second material, and the fatigue resistance, high temperature resistance and tensile strength of the first material are all superior to those of the second material. The wire diameter of the first coils is larger than that of the second coils.

Description

Stator assembly and motor

[0001] This application claims priority to Chinese Patent Application No. 202422209477.2, filed on September 9, 2024, Chinese Patent Application No. 202422209837.9, filed on September 9, 2024, and 202411259472.9, the contents of all three of which are incorporated herein by reference in their entirety as part of the present application. TECHNICAL FIELD

[0002] The present disclosure relates to the field of electric machines, in particular to a stator assembly and a motor comprising the same. BACKGROUND

[0003] There are mainly three kinds of wires used in the coils of electric machines at present: enameled copper wire, enameled aluminum wire and copper-clad aluminum wire. In terms of quality, copper wire is the best, but the price of copper is high at present, and the use of all copper wire will inevitably greatly increase the cost of the electric machine. Some electric machines use enameled aluminum wire or copper-clad aluminum wire to replace copper wire to reduce cost, but the performance of enameled aluminum wire or copper-clad aluminum wire is not as good as that of enameled copper wire (the resistivity of enameled aluminum wire or copper-clad aluminum wire is greater than that of copper wire, so in the case of the same current, the coil of enameled aluminum wire or copper-clad aluminum wire generates more heat than the coil of copper wire, which in turn affects the temperature control and efficiency of the electric machine).

[0004] If all the enameled copper wire is replaced by enameled aluminum wire, under the premise of ensuring the efficiency of the electric machine, because the resistivities of the two are different, the enameled aluminum wire needs to increase the cross-sectional area to obtain the same resistance and current as the enameled copper wire, which will inevitably lead to an increase in the volume of the enameled aluminum wire coil. In order to embed the enameled aluminum wire coil into the slot, the outer diameter and thickness of the stator must be increased to expand the slot. In addition, when used under full load, the enameled aluminum wire coil will generate a lot of heat due to its high resistance, which will directly affect the service life of the electric machine. Specifically, compared with enameled copper wire, enameled aluminum wire has a small current-carrying capacity and a large resistivity, generates a lot of heat during use, and is easy to burn out the electric machine. In addition, the mechanical strength of enameled aluminum wire is also poorer than that of enameled copper wire, and it is more prone to wire breakage. For some electric machines, the vibration will also increase.

[0005] How to reduce the cost of the coil without increasing the volume of the stator assembly and affecting the performance and service life of the electric machine has become a problem that needs to be solved for electric machines at present.

[0006] SUMMARY

[0007] The purpose of the present disclosure is to at least solve the problems existing in the prior art, and the present disclosure provides a stator assembly, comprising a stator core, comprising an annular stator yoke and a plurality of stator teeth connected to the radially inner side of the stator yoke, the plurality of stator teeth being spaced apart from each other in the circumferential direction; a winding, each phase winding comprising a first coil group and a second coil group in parallel, one first coil and one second coil being wound on each stator tooth, the first coil group comprising at least one first coil, the second coil group comprising at least one second coil, the first coil of the first coil group and the second coil of the second coil group of each phase winding being wound on the same stator tooth. Wherein, the first coil is wound around the stator tooth, the second coil is wound outside the first coil, the first coil comprises a first conductive material, the second coil comprises a second conductive material, the resistivity of the first material is less than the resistivity of the second material, and the fatigue resistance, high temperature resistance and tensile strength of the first material are better than the fatigue resistance, high temperature resistance and tensile strength of the second material, the wire diameter of the first coil is greater than the wire diameter of the second coil.

[0008] For example, according to some embodiments of the present disclosure, the ratio of the wire diameter of the first coil to the wire diameter of the second coil is in the range of 1.1 to 1.4.

[0009] For example, according to some embodiments of the present disclosure, the ratio of the wire diameter of the first coil to the wire diameter of the second coil is 1.2.

[0010] For example, according to some embodiments of the present disclosure, on each stator tooth, the ratio of the number of turns of the second coil to the number of turns of the first coil is in the range of 0.8 to 1.2.

[0011] For example, according to some embodiments of the present disclosure, on each stator tooth, the number of turns of the second coil is equal to the number of turns of the first coil.

[0012] For example, according to some embodiments of the present disclosure, the stator assembly further comprises a stator skeleton, the stator skeleton being wrapped on both sides of the stator core in the axial direction and forming a wire slot accommodating the first coil and the second coil on both sides of the stator tooth in the axial direction.

[0013] For example, according to some embodiments of the present disclosure, the winding is arranged in the form of a concentrated winding.

[0014] For example, according to some embodiments of the present disclosure, the connection type of the winding is Y connection.

[0015] For example, according to some embodiments of the present disclosure, the first coil is composed of enameled copper wire, and the second coil is composed of enameled aluminum wire.

[0016] For example, according to some embodiments of the present disclosure, the first coil set comprises a plurality of first coils connected in series, and the second coil set comprises a plurality of second coils connected in series.

[0017] For example, according to some embodiments of the present disclosure, the first coil set and the second coil set of each phase winding are welded to the same terminal.

[0018] For example, according to some embodiments of the present disclosure, the stator assembly comprises a three-phase winding.

[0019] The present disclosure also proposes an electric machine comprising the stator assembly of any of the above embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 shows a perspective view of a stator assembly according to an embodiment of the present disclosure;

[0021] Fig. 2 shows a cross-sectional view of a part of the stator assembly taken in a plane passing through the central axis of the stator assembly;

[0022] Fig. 3 shows a connection diagram of the first coil and the second coil;

[0023] Fig. 4 shows a comparison diagram of the efficiency of an electric machine according to a first embodiment of the present disclosure and a copper wire electric machine;

[0024] Fig. 5 shows the efficiency difference between the electric machine according to the first embodiment of the present disclosure and the copper wire electric machine;

[0025] Fig. 6 shows a cooperation diagram of the first winding and the second winding with a terminal according to the first embodiment of the present disclosure;

[0026] Fig. 7 shows a diagram of the welding process of the first winding and the second winding with a terminal according to the present disclosure;

[0027] Fig. 8 shows a perspective view of the cooperation of the stator core with a terminal according to the first embodiment of the present disclosure;

[0028] Fig. 9 shows a cross-sectional view of the plastic sealing part surrounding other parts according to the first embodiment of the present disclosure;

[0029] Fig. 10 shows a perspective view of the stator assembly according to the first embodiment of the present disclosure;

[0030] Fig. 11 shows the efficiency difference between the electric machine according to a second embodiment of the present disclosure and the copper wire electric machine;

[0031] Fig. 12 shows a cooperation diagram of the winding according to the present disclosure with a terminal according to the second embodiment of the present disclosure;

[0032] Fig. 13 shows a diagram of the electrical connection of the first terminal and the second terminal according to the second embodiment of the present disclosure;

[0033] Fig. 14 shows a cross-sectional view of a plastic sealing portion according to the present disclosure surrounding other components, taken at a first terminal according to a second embodiment of the present disclosure;

[0034] Fig. 15 shows a perspective view of a stator assembly according to a second embodiment of the present disclosure.

[0035] Reference numeral 1 - stator core 11 - stator yoke 12 - stator tooth 2 - winding 21 - first coil 211 - first wire 22 - second coil 221 - second wire 3 - stator frame 4 - terminal 41 - first terminal 42 - second terminal 43 - connecting piece 5 - plastic sealing portion 6 - electrode rod DETAILED DESCRIPTION

[0036] In order to make the purpose, scheme and advantages of the technical solutions of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below in combination with the drawings of the specific embodiments of the present disclosure. Unless otherwise specified, the terms used herein have the meanings commonly understood in the art. The same reference numerals in the drawings represent the same components.

[0037] In the description of the present disclosure, it should be noted that unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting” should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0038] In the present disclosure, for the convenience of description, the direction of the center axis of the annular stator yoke is designated as the axial direction, the radial direction of the annular stator yoke is designated as the radial direction, and the direction around the center axis of the annular stator yoke is designated as the circumferential direction.

[0039] The present disclosure proposes a stator assembly with a first coil 21 and a second coil 22, which comprises a stator core 1, and the first coil 21 and the second coil 22 are wound on the stator core 1. Specifically, the stator core 1 of the stator assembly can comprise an annular stator yoke 11 and a plurality of stator teeth 12 connected to the radially inner side of the stator yoke 11, the plurality of stator teeth 12 are spaced apart from each other in the circumferential direction, in particular, uniformly and equidistantly, thereby leaving space for the first coil 21 and the second coil 22 to be wound. For example, the number of stator teeth 12 is 24 as shown in FIG. 1, but the number of stator teeth in the present disclosure is not limited to 24, and can also be 3, 6, 9, 12, 15, 18, 21, etc. The radially inner top end of the stator teeth 12 extends at least partially to both sides in the circumferential direction to form slot grooves on both sides in the circumferential direction, facilitating winding and can be used to prevent the coil from coming off.

[0040] The stator core 1 can be made by stamping a stack of silicon steel sheets. Specifically, a plurality of silicon steel sheets can be stamped into a predetermined shape and fixed to each other by riveting. The thickness of the silicon steel sheets can be 0.2-0.5 mm, preferably, the thickness of the silicon steel sheets can be 0.35 mm.

[0041] In addition, the stator core 1 can also be made of soft magnetic composite (SMC) material by powder metallurgy. The stator core 1 can be integrally formed, or can be made into stator blocks, and then a plurality of stator blocks are spliced into the stator core 1. Other methods of forming the stator core are also applicable to the present disclosure.

[0042] The stator assembly according to the present disclosure can further comprise a stator skeleton 3, which can be wrapped on both sides of the stator core 1 in the axial direction to form slot grooves on both sides of the stator core 1 in the axial direction to accommodate the coils, as shown in FIGS. 1 and 2. Thus facilitating the winding of the first coil 21 and the second coil 22, and being conducive to supporting the first coil 21 and the second coil 22, and resisting the action of electromagnetic force, preventing the coil from deforming to cause short circuit, and reducing the probability of motor failure.

[0043] The number of windings 2 can be multiple, for example, can be set to 3, three-phase windings 2 are independent of each other, respectively corresponding to U, V, W three-phase; or can be set to 2, two-phase windings 2 are independent of each other, respectively corresponding to two-phase. The winding 2 can comprise at least one first coil 21 and at least one second coil 22, in particular, comprising a first coil group of a plurality of first coils 21 connected in series and a second coil group of a plurality of second coils 22 connected in series. The number of first coils 21 of the first coil group and the number of second coils 22 of the second coil group are the same, and for each phase winding 2, the first coil 21 of the first coil group and the second coil 22 of the second coil group are wound on the same stator tooth.

[0044] Further, the first coil 21 and the second coil 22 of each phase winding 2 are alternately arranged on the adjacent stator teeth in sequence, i.e. the first coil 21 and the second coil 22 of the same phase winding 2 are arranged on the stator teeth which are separated by two stator teeth. For example, the 24 stator teeth of the electric motor 1 are sequentially numbered as 1-24, the first coil 21 and the second coil 22 of one phase winding 2 are arranged on the 1st, 4th, 7th, 10th, 13th, 16th, 19th and 22nd stator teeth, the first coil 21 and the second coil 22 of another phase winding 2 are arranged on the 2nd, 5th, 8th, 11th, 14th, 17th, 20th and 23rd stator teeth, and the first coil 21 and the second coil 22 of the remaining phase winding 2 are arranged on the 3rd, 6th, 9th, 12th, 15th, 18th, 21st and 24th stator teeth.

[0045] The first coil 21 and the second coil 22 comprise different conductive materials, specifically, the first coil 21 comprises a first material for conducting electricity, and the second coil 22 comprises a second material for conducting electricity. The first material can be more expensive than the second material, but the first material has some better properties than the second material, for example, the first material has better fatigue resistance, high temperature resistance and tensile strength than the second material, and the first material has a smaller resistivity than the second material. The present disclosure aims to reduce the manufacturing cost of the stator assembly by using a cheaper material with poorer performance, but replacing all the materials with poorer performance will not guarantee the performance of the stator assembly or will increase the volume of the stator assembly. Therefore, the present disclosure adopts a partial replacement scheme, which uses a cheaper material at least partially to reduce the manufacturing cost while guaranteeing the performance of the stator assembly and without changing the volume of the stator assembly.

[0046] The first material and the second material mentioned above can be a single metal material or an alloy material. For example, the first material can be a copper alloy material or pure copper, and the second material can be an aluminum alloy material or pure aluminum. The first coil can be, for example, a lacquered copper wire, and the second coil can be, for example, a lacquered aluminum wire, where the lacquered copper wire can be made of pure copper or a copper alloy, and the lacquered aluminum wire can be made of pure aluminum or an aluminum alloy.

[0047] Specifically, the stator assembly according to the present disclosure connects the first coil group and the second coil group in parallel, for example as shown in FIG. 3, which can also be used in a 3-phase circuit, whereby the number of windings 2 is set to 3, corresponding to U-phase, V-phase and W-phase; or the number of windings 2 can be set to 2, corresponding to two phases. Among them, the three-phase winding 2 can be Y-type connection, and in each phase winding 2, the first coil group and the second coil group are connected in parallel. When the number of turns of the winding, the rotor and the rotational speed are determined, the back electromotive force of the motor is determined, and under the condition that the power of the motor is constant, the total current of the motor is constant, and the total torque of the motor is constant. Therefore, this parallel structure is beneficial to reduce the total resistance of the motor winding, thereby reducing the total heat generation of the motor.

[0048] In particular, the winding 2 of the present disclosure is preferably wound on the stator core 1 in the form of concentrated winding, which has simple structure and is easy to maintain.

[0049] Further, the first coil 21 is wound adjacent to the stator tooth 12, and the second coil 22 is wound on the periphery of the first coil 21, for example as shown in FIG. 2, the inner 3 layers of the coil are the first coil 21, and the outer 3 layers of the coil are the second coil 22. The first coil 21 is closer to the stator core 1, so the magnetic lines generated by the first coil 21 are all concentrated to conduct through the stator core 1; the second coil 22 is close to the outside of the stator, and only part of the magnetic lines generated by the second coil 22 conduct through the stator core 1, and part of the magnetic lines conduct through the air. The magnetic conductivity of the stator core 1 is much better than that of the air, and the magnetic field generated by the first coil 21 in the inner layer will better act on the rotor.

[0050] On this basis, the first coil 21 is arranged to have a wire diameter larger than that of the second coil 22. Preferably, the number of turns of the first coil 21 is substantially the same as that of the second coil 22 on each stator tooth. In particular, each first coil 21 is identical, and each second coil 22 is identical. Further, in the present disclosure, the first material selected for the first coil 21 has a resistivity smaller than that of the second material selected for the second coil 22, so that the total resistance of the first coil 21 is smaller than that of the second coil 22 on each stator tooth. As the resistance of the first coil 21 is smaller than that of the second coil 22 on each stator tooth, the current flowing through the first coil 21 is larger than that of the second coil 22, and the magnetic field strength generated by the first coil 21 is larger than that of the second coil 22. In combination with the magnetic conduction advantage of being closer to the stator core 1, the torque acting on the rotor provided by the first coil 21 is larger than that of the second coil 22, i.e. the proportion of the total torque provided by the first coil 21 is larger than that of the second coil 22. The total torque of the motor is mainly provided by the first coil 21 in the inner layer, and the second coil 22 in the outer layer supplements part of the torque and assists in providing back electromotive force. For example, more than 65%, more than 70%, more than 75%, more than 80% of the total torque of the motor is provided by the first coil 21. Thus, this structure provides more torque than a structure in which the second coil is arranged in the inner layer and the first coil is arranged in the outer layer or the first coil and the second coil are mixedly wound, and thus, in the case of replacing the first coil with the second coil, the torque provided does not decrease significantly, and the demand can still be met.

[0051] As the first coil 21 provides the main torque of the motor, the first coil 21 itself will be subjected to greater counterforce, and thus, in order to prevent the first coil 21 from breaking, being damaged, etc. to cause short circuit or open circuit, etc., the first material selected for the first coil 21 preferably has better mechanical properties (at least better than the second material), in particular, fatigue resistance and tensile strength, so that the first coil 21 can withstand greater counterforce, which is beneficial to providing a larger proportion of total torque. Conversely, as the second coil 22 provides less torque, the second material can be subjected to less counterforce, and the selection requirement of the second material can be relaxed, and a material with weaker mechanical properties but lower price can be selected to reduce costs.

[0052] Further, since the current flowing through the first coil 21 is greater than the current flowing through the second coil 22, the amount of heat generated is proportional to the square of the current, and the effect of the current on the generated heat is greater than the resistance, more heat is generated in the first coil 21, and less heat is generated in the second coil 22. Because the first coil 21 is located in the inner coil, the heat is more difficult to dissipate, and the heat resistance of the first material selected for the first coil 21 needs to be better. On the contrary, since the second coil 22 not only generates less heat, but also the second coil 22 is located in the outer coil, it is easier to dissipate heat, and the requirement for the heat resistance of the second material selected for the second coil 22 can be relaxed, and a cheaper material can be selected without burning out the motor.

[0053] Further, according to the stator assembly of the present disclosure, the selection of the wire diameter and the selection of the number of turns affect each other, and the different wire diameters can be adjusted according to the motor performance. In the case where other conditions remain unchanged, the present disclosure selects different wire diameters to optimize the performance of the motor. In the case where the motor wire slot pitch remains unchanged, the thicker the wire diameter of the first coil 21 and the second coil 22, the smaller the total resistance after parallel connection, the smaller the heat generation, and the better the performance; but the larger the wire diameter of the first coil 21 and the second coil 22, the smaller the number of turns, the lower the back electromotive force, the larger the total current, the larger the heat generation, and the worse the performance of the motor. Therefore, the selection of the wire diameter of the first coil and the second coil is the result of comprehensive consideration, and cannot be considered only one factor. Therefore, under the premise of considering the slot fill rate and ensuring that the number of turns is sufficient, the thicker the wire diameter of the first coil and the second coil, the better.

[0054] Therefore, according to the result of comprehensive consideration, according to the stator assembly of the present disclosure, the wire diameter of the first coil 21 of the present disclosure is preferably between 1.1 times and 1.4 times the wire diameter of the second coil 22, and is preferably 1.2 times the wire diameter of the second coil 22. On each stator tooth, the number of turns of the second coil 22 can be 0.8-1.2 times the number of turns of the first coil 21, and preferably, on each stator tooth, the number of turns of the second coil 22 is equal to the number of turns of the first coil 21. In particular, on each stator tooth, the total resistance of the first coil 21 is 0.3-0.5 times the total resistance of the second coil 22, and is preferably 0.4 times. In particular, each first coil 21 is the same, and each second coil 22 is the same.

[0055] Further, for the stator assembly with both the first coil 21 and the second coil 22, since the first coil 21 and the second coil 22 need to be powered, the first wire 211 (e.g., enameled copper wire) of the first coil 21 and the second wire 221 (e.g., enameled aluminum wire) of the second coil 22 need to be connected to the terminal.

[0056] Specifically, the first winding 211 of the first coil 21 and the second winding 221 of the second coil 22 are electrically connected to the same terminal 4, in particular, the first winding 211 of the first coil group and the second winding 221 of the second coil group of each phase winding 2 are electrically connected to the same terminal 4, to realize the parallel connection of the first coil group and the second coil group of each phase winding 2. For example, FIGS. 6-10 show a first embodiment according to the present disclosure. FIG. 6 shows that the first winding 211 and the second winding 221 are simultaneously electrically connected to the terminal 4, in particular, welded to the terminal 4.

[0057] FIG. 7 shows the welding process of the first winding 211 and the second winding 221 to the terminal 4. In order to facilitate welding, the terminal surface is plated with nickel or tin. The first winding 211 and the second winding 221 are first positioned at the welding position of the terminal 4, for example, as shown in FIG. 7, the terminal 4 includes a wire slot that accommodates the winding, which is the welding position. The width of the wire slot is greater than the wire diameter of the first winding 211 of the first coil 21 and the wire diameter of the second winding 221 of the second coil 22, and less than twice the wire diameter of the first winding 211 of the first coil 21 and twice the wire diameter of the second winding 221 of the second coil 22. The windings in the wire slot are arranged in a single row, thereby facilitating an increase in the welding quality.

[0058] The terminal 4 and the first winding 211 and the second winding 221 are placed between two electrode rods 6, and the welding process is realized by the electrode rods 6. For example, the terminal is heated to between 155°C and 180°C, depending on the heat-resistant temperature grade of the first winding 211 and the second winding 221, to melt the paint on the surface of the first winding 211 and the second winding 221, exposing the conductive metal wires in the inner layer of the first winding 211 and the second winding 221, such as the copper wire in the inner layer of the first winding 211 and the aluminum wire in the inner layer of the second winding 221. The terminal 4 is pressed tightly to make the copper wire and the aluminum wire in the inner layer of the first winding 211 and the second winding 221 fully contact the surface of the terminal 4, and then cooled. After cooling, the paint in the molten state solidifies, re-coating the copper wire and the aluminum wire and the terminal 4, and the welding is completed.

[0059] The number of terminals 4 can be three, corresponding to the three-phase winding 2, so that each phase winding 2 is connected to one terminal 4. A terminal slot can be reserved on the stator frame 3 for the terminal 4 to be inserted and positioned therein, as shown in the first embodiment of FIG. 8. The terminal 4 can be disposed on one side of the stator core 1 in the axial direction of the stator core 1, and the terminal 4 has a free end extending away from the stator core 1.

[0060] Further, in order to realize the protection of the electrical connection part and the coil, the stator assembly further comprises a plastic sealing part 5. For example, after welding, the entire stator assembly is plastic sealed with BMC material, and the electrical connection part (for example, the welding part) of the terminal 4 and the first winding 211 of the first coil group and the second winding 221 of the second coil group, and the first coil 21 and the second coil 22 are covered, as shown in FIG. 9. In this way, the air is isolated, the coil is prevented from being oxidized, the electrochemical reaction between the first winding and the second winding (for example, copper wire and aluminum wire) is prevented, the corrosion is reduced, and in addition, physical protection can be provided, so that the first coil and the second coil are further fixed, and the vibration of the coil during the operation of the motor is reduced.

[0061] As shown in FIG. 10, the free end of the terminal 4 is exposed outside the plastic sealing part 5 for subsequent wiring process. For example, three terminals 4 can be arranged at adjacent stator teeth to facilitate the simplification of plastic sealing.

[0062] According to the first embodiment, as shown in FIGS. 6-9, the first winding 211 and the second winding 221 are connected to the same terminal, but this wiring method puts higher requirements on the automatic welding of the terminal. In particular, since there are two kinds of windings, the first winding 211 and the second winding 221, on the terminal, the welding conditions are more stringent. If the welding control is not good, not only will the wire be disconnected or the contact be poor, but if the welding causes the first winding 211 and the second winding 221 on the terminal to be exposed to the air, the first winding 211 and / or the second winding 221 will be oxidized, and electrochemical corrosion will occur between the first winding 211 and the second winding 221, for example, the second winding 221 (if the first winding is an enameled copper wire, and the second winding is an enameled aluminum wire) will be severely heated or disconnected, ultimately resulting in reduced motor efficiency or reduced motor service life.

[0063] In this regard, according to the second embodiment of the present disclosure, a wiring structure is provided, specifically, different first terminals 41 and second terminals 42 are provided, the first winding 211 of the first coil 21 is electrically connected to the first terminal 41, and the second winding 221 of the second coil 22 is electrically connected to the second terminal 42, and the electrical connection is realized by welding, as shown in FIGS. 12-15. FIG. 12 shows that the first winding 211 is welded to the first terminal 41, and the second winding 221 of the second coil 22 can be welded to the second terminal 42 in the same way. For example, the first terminal 41 and the second terminal 42 can also be plated with nickel or tin at the welding part.

[0064] In this way, the first winding 211 and the second winding 221 are welded at two different terminals respectively, which solves the problems of electrochemical corrosion and different temperature resistance of the two kinds of enameled wires, reduces the welding requirements, is conducive to improving the welding quality, is suitable for large-scale industrial automatic production, and has great practical value.

[0065] Further, the first terminals 41 and the second terminals 42 can be provided in a number corresponding to the number of phases of the winding, for example, three first terminals 41 and three second terminals 42 can be provided when the winding has three phases, or two first terminals 41 and two second terminals 42 can be provided when the winding has two phases. The first terminals 41 and the second terminals 42 can be alternately and evenly spaced as shown in FIG. 15. The stator core 3 can be provided with terminal slots for the terminals to be inserted and positioned. In particular, each terminal is provided at a stator tooth, and six terminals are provided at six adjacent stator teeth, which facilitates the subsequent potting step.

[0066] The first terminals 41 and the second terminals 42 can be identical, and the first terminals 41 and the second terminals 42 can include wire slots for accommodating the windings. The width of the wire slots is greater than the wire diameter of the first windings 211 of the first coils 21 and the wire diameter of the second windings 221 of the second coils 22, and less than twice the wire diameter of the first windings 211 of the first coils 21 and twice the wire diameter of the second windings 221 of the second coils 22. This allows the windings in the wire slots to be arranged in a single row, thereby facilitating the increase of the welding quality.

[0067] The first windings 211 of the first coil groups of the three-phase winding 2 can be electrically connected to one of the three first terminals 41, and the second windings 221 of the second coil groups of the three-phase winding 2 can be electrically connected to one of the three second terminals 41, thereby realizing the independence of the three-phase winding 2. The first terminals 41 and the second terminals 42 are electrically connected in pairs, for example, as shown in FIG. 13, the first terminals 41 and the second terminals 42 are electrically connected by a connecting member 43 (such as a wire), so that the first coil groups and the second coil groups in each phase winding 2 are connected in parallel.

[0068] Further, in order to realize the protection of the electrical connection parts and the coils, the stator assembly further comprises a potting part 5, for example, after welding, the entire stator assembly is potted with BMC material, in particular, the electrical connection parts (for example, the welding parts) of the first terminals 41 and the second terminals 42 with the first windings 211 of the first coil groups and the second windings 221 of the second coil groups are covered, and the first coils 21 and the second coils 22 are covered. For example, FIG. 14 shows a cross-sectional view of the potting part according to the present disclosure surrounding other components taken at the first terminal 41, and the case at the second terminal 42 can be similarly applied. In this way, air is isolated, oxidation of the coils is prevented, electrochemical reaction between the first windings and the second windings (such as copper wire and aluminum wire) is prevented, corrosion is reduced, in addition, physical protection can be provided, so that the first coils and the second coils are further fixed, and the vibration of the coils during the operation of the motor is reduced.

[0069] As shown in FIGS. 14 and 15, the free ends of the first terminals 41 and the second terminals 42 are exposed outside the plastic sealing part 5 for subsequent wiring procedures.

[0070] The stator assembly can further include a cap (not shown) for fixing the terminals, for example, one cap fixing a plurality of terminals. After the terminals are welded, BMC injection is performed to encapsulate the coils and the lower half of the terminals into the BMC, thereby isolating the coils and the terminals from air. The stator end portion where the terminals are located bears a large pressure during the injection, and if the terminals are not protected by the cap, the terminals can be squeezed during the injection, causing the upper half of the terminals to also be encapsulated into the BMC, thereby preventing subsequent wiring procedures.

[0071] The disclosure further provides an electric machine including the above-described stator assembly.

[0072] After actual experimental tests on a full-copper winding electric machine and an electric machine according to the disclosure (for example, a copper-aluminum winding electric machine), the difference between the efficiencies of the two electric machines is between 0.58% and 1.05% under the same torque.

[0073] The test conditions are as follows:

[0074] As shown in FIGS. 4 and 5, under the same torque, the efficiency of the copper wire electric machine is better than that of the electric machine according to the first embodiment of the disclosure, and the difference between the efficiencies of the two electric machines is between 0.20% and 1.37%, wherein the difference between the efficiencies is the largest at 1.37% at 100 N·m, and the difference between the efficiencies is the smallest at 0.20% at 20 N·m. As shown in FIG. 11, under the same torque, the efficiency of the copper wire electric machine is better than that of the electric machine according to the second embodiment of the disclosure, and the difference between the efficiencies of the two electric machines is between 0.07% and 1.08%, wherein the difference between the efficiencies is the largest at 1.08% at 100 N·m, and the difference between the efficiencies is the smallest at 0.07% at 30 N·m.

[0075] Under the test conditions of the present patent, the φ260 motor has a corresponding torque of 95.5 N·m at full load output power of 15 kW. As can be seen from FIG. 5, the difference between the efficiencies of the copper wire motor and the motor of the present disclosure is basically controlled within 0.7% between 10 N·m and 80 N·m, and the difference in efficiency between the two starts to increase significantly only when the motor approaches full load output power. Referring to GB 30253-2013 variable frequency drive permanent magnet synchronous motor efficiency grade, the motor of the present disclosure meets the first energy efficiency standard between 20 N·m and 80 N·m, i.e., the power is between 3.1 kW and 12.6 kW. Generally, a motor does not work at full load all the time. Although the motor of the present disclosure has a lower efficiency than the copper wire motor, the motor of the present disclosure can meet the first energy efficiency standard within a relatively wide power output range, and by replacing half of the expensive first material (e.g., copper) with the second material (e.g., aluminum), the cost will be greatly reduced under the condition that the service life and the stator volume remain unchanged.

[0076] It should be understood that the above description is intended to be illustrative and not restrictive. For example, the above-described embodiments (and / or aspects thereof) can be used in combination with each other. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the scope thereof. The functions or the performances of various elements or modules described herein are for illustration only and are by no means limiting, but are merely exemplary embodiments. After reading the above description, many other embodiments and modifications will be apparent to those skilled in the art within the spirit and scope of the claims. Therefore, the scope of the present disclosure should be determined by reference to the appended claims and their full scope of equivalents.

[0077] In the appended claims, the terms "comprise" and "wherein" are used as simple English equivalents of the respective terms "include" and "wherein." Furthermore, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Claims

1. A stator assembly comprising a stator core comprising an annular stator yoke and a plurality of stator teeth connected to a radially inner side of the stator yoke, the plurality of stator teeth being mutually spaced apart in a circumferential direction, windings, each phase winding comprising a first coil set and a second coil set in parallel, the first coil set comprising at least one first coil, the second coil set comprising at least one second coil, one first coil and one second coil being wound on each of the stator teeth, the first coil of the first coil set and the second coil of the second coil set of each phase winding being wound on the same stator tooth, wherein each first coil being wound around the corresponding stator tooth, each second coil being wound around the corresponding first coil, the first coil comprising a first electrically conductive material, the second coil comprising a second electrically conductive material, the first material having a resistivity which is lower than the resistivity of the second material, and the first material having a fatigue resistance, a high temperature resistance, a tensile strength which are superior to the fatigue resistance, the high temperature resistance, the tensile strength of the second material, the first coil having a wire diameter which is greater than the wire diameter of the second coil or the total resistance of the first coil set being lower than the total resistance of the second coil set.

2. The stator assembly according to claim 1, wherein the ratio of the wire diameter of the first coil to the wire diameter of the second coil is in the range of 1.1 to 1.4, in particular, the ratio of the wire diameter of the first coil to the wire diameter of the second coil is 1.

2.

3. The stator assembly according to claim 1, wherein the ratio of the total resistance of the first coil set to the total resistance of the second coil set of each phase winding is in the range of 0.3 to 0.5, in particular, the ratio of the total resistance of the first coil set to the total resistance of the second coil set of each phase winding is 0.

4.

4. The stator assembly according to claim 2 or 3, wherein the ratio of the number of turns of the second coil to the number of turns of the first coil on each stator tooth is in the range of 0.8 to 1.

2.

5. The stator assembly according to claim 4, wherein the number of turns of the second coil is equal to the number of turns of the first coil on each stator tooth.

6. The stator assembly according to claim 1, wherein the stator assembly further comprises a stator back iron, the stator back iron being axially enveloping on both sides of the stator core and forming wire slots on both axial sides of the stator teeth for accommodating the first and second coils.

7. The stator assembly according to claim 1, wherein the windings are arranged in a concentrated winding manner.

8. The stator assembly according to claim 7, wherein the connection type of the windings is a Y-connection.

9. The stator assembly according to any one of claims 1 to 8, wherein the first coil is composed of an enameled copper wire, the second coil is composed of an enameled aluminum wire.

10. The stator assembly according to any one of claims 1 to 8, wherein the first coil set comprises a plurality of first coils in series, the second coil set comprises a plurality of second coils in series.

11. The stator assembly according to any one of claims 1 to 8, wherein the first coil set and the second coil set of each phase winding are welded to the same connection terminal.

12. The stator assembly of claim 11, wherein, the terminal comprises a wire slot accommodating the wire, the wire slot having a width greater than the wire diameter of the first coil and the wire diameter of the second coil, and less than twice the wire diameter of the first coil and twice the wire diameter of the second coil.

13. The stator assembly of any one of claims 1-8, wherein, a first terminal, the first coil set of each phase winding is electrically connected to one of the first terminals, a second terminal, the second coil set of each phase winding is electrically connected to one of the second terminals, the first terminals and the second terminals are electrically connected in pairs such that the first coil set and the second coil set in each phase winding are connected in parallel.

14. The stator assembly of claim 13, wherein, the first coil set comprises a plurality of first coils connected in series, and the second coil set comprises a plurality of second coils connected in series.

15. The stator assembly of claim 13, wherein, the stator assembly further comprises a plastic encapsulation portion, the plastic encapsulation portion surrounds each phase winding, and also surrounds the electrical connections of the first terminals and the second terminals to the first coil set and the second coil set, respectively, free ends of the first terminals and the second terminals are exposed outside the plastic encapsulation portion.

16. The stator assembly of any one of claims 1-8, wherein, the stator assembly comprises three phase windings.

17. An electric machine comprising the stator assembly of any one of claims 1-13.

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