Stator assembly and motor

Abstract

The present disclosure proposes a stator assembly including a stator core including 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 spaced apart from each other in a circumferential direction; each phase of winding comprises a first coil group and a second coil group which are connected in parallel, each stator tooth is wound with a first coil and a second coil, the first coil group comprises at least one first coil, and the second coil group comprises 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 phase winding are wound on the same stator teeth. Wherein the first coil is wound around the stator teeth, the second coil is wound around the periphery of the first coil, the first coil comprises a conductive first material, the second coil comprises a conductive second material, the resistivity of the first material is smaller than that of the second material, and the total resistance of the first coil group of each phase winding is smaller than that of the second coil group.

Description

Technical Field

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

[0002] There are mainly three types of wires used in current motor coils: enameled copper wires, enameled aluminum wires, and copper-clad aluminum wires. In terms of quality, copper wires are the best, but the price of copper is currently high, and using all copper wires will inevitably greatly increase the cost of the motor. Some motors use enameled aluminum wires or copper-clad aluminum wires to replace copper wires to reduce costs, but the performance of enameled aluminum wires or copper-clad aluminum wires is inferior to that of enameled copper wires (the resistivity of enameled aluminum wires or copper-clad aluminum wires is greater than that of copper wires. Therefore, in the case of the same current, the coil heating of enameled aluminum wires or copper-clad aluminum wires is more serious than that of copper wire coils, which in turn affects the temperature control and efficiency of the motor).

[0003] If all enameled copper wires are replaced with enameled aluminum wires, on the premise of ensuring the same motor efficiency, due to the different resistivity of the two, 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 wire slot, only the outer diameter and thickness of the stator can be increased to expand the wire slot. In addition, when operating at full load, the enameled aluminum wire coil will heat up severely due to its large resistance, directly affecting the service life of the motor. Specifically, compared with enameled copper wires, enameled aluminum wires have a smaller current-carrying capacity, a larger resistivity, and a higher heat generation during use, making it easy to burn out the motor. In addition, the mechanical strength of enameled aluminum wires is also worse than that of enameled copper wires, and wire breakage is more likely to occur. For some motors, the vibration will also increase.

[0004] How to reduce the cost of the coil without increasing the volume of the stator assembly and without affecting the performance and service life of the motor has become an urgent problem to be solved in current motors. Summary of the Utility Model

[0005] The object of the present disclosure is to at least solve the disadvantages existing in the prior art. The present disclosure provides a stator assembly, which includes a stator core including an annular stator yoke and a plurality of stator teeth connected to the radial inner side of the stator yoke, and the plurality of stator teeth are circumferentially spaced apart from each other; a winding, each phase winding including a first coil group and a second coil group connected in parallel, one first coil and one second coil are wound around each stator tooth, the first coil group includes at least one first coil, the second coil group includes at least one second coil, and the first coils of the first coil group and the second coils of the second coil group of each phase winding are wound around the same stator tooth. Wherein, the first coil is wound around the stator tooth, the second coil is wound around the periphery of the first coil, the first coil includes a conductive first material, the second coil includes a conductive second material, the resistivity of the first material is less than that of the second material, and the total resistance of the first coil group of each phase winding is less than the total resistance of the second coil group.

[0006] For example, according to some embodiments of the present disclosure, the ratio of the total resistance of the first coil group to the total resistance of the second coil group of each phase winding is in the range of 0.3 to 0.5.

[0007] For example, according to some embodiments of the present disclosure, the ratio of the total resistance of the first coil group to the total resistance of the second coil group of each phase winding is 0.4.

[0008] 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.

[0009] 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.

[0010] For example, according to some embodiments of the present disclosure, the stator assembly further includes a stator skeleton, and the stator skeleton axially wraps around both sides of the stator core and forms wire grooves for accommodating the first coil and the second coil on the axial two sides of the stator teeth.

[0011] For example, according to some embodiments of the present disclosure, the winding is arranged in a concentrated winding manner.

[0012] For example, according to some embodiments of the present disclosure, the wiring type of the winding is Y-type wiring.

[0013] For example, according to some embodiments of the present disclosure, the first winding is composed of enameled copper wire, and the second winding is composed of enameled aluminum wire.

[0014] For example, according to some embodiments of the present disclosure, the first coil group includes a plurality of first coils connected in series, and the second coil group includes a plurality of second coils connected in series.

[0015] The present disclosure also provides a motor, including the stator assembly according to any one of the above embodiments. Description of the Drawings

[0016] Figure 1 A perspective view showing the stator assembly according to an embodiment of the present disclosure;

[0017] Figure 2 A cross-sectional view showing a part of the stator assembly taken along a plane passing through the central axis of the stator assembly;

[0018] Figure 3 A schematic diagram showing the connection of the first coil and the second coil;

[0019] Figure 4 A graph showing the efficiency comparison between the motor according to the present disclosure and a copper wire motor;

[0020] Figure 5 A graph showing the efficiency difference between the motor according to the present disclosure and a copper wire motor;

[0021] Figure 6 A schematic diagram showing the cooperation of the first winding and the second winding with the terminal according to the present disclosure;

[0022] Figure 7 A schematic diagram showing the soldering process of the first winding and the second winding with the terminal according to the present disclosure;

[0023] Figure 8 A perspective view showing the cooperation of the stator core and the terminal according to the present disclosure;

[0024] Figure 9 A cross-sectional schematic diagram showing the encapsulation part surrounding other components according to the present disclosure;

[0025] Figure 10 A perspective schematic diagram showing the stator assembly according to the present disclosure.

[0026] Reference Signs

[0027] 1 - Stator Core

[0028] 11 - Stator Yoke

[0029] 12 - Stator Tooth

[0030] 2 - Winding

[0031] 21 - First Coil

[0032] 211 - First Winding

[0033] 22——Second coil

[0034] 221——Second winding

[0035] 3——Stator skeleton

[0036] 4——Terminal

[0037] 5——Plastic encapsulation part

[0038] 6——Electrode rod Specific embodiments

[0039] In order to make the objectives, solutions and advantages of the technical solutions of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments of the present disclosure. Unless otherwise specified, the terms used herein have the ordinary meanings in the art. The same reference numerals in the drawings represent the same components.

[0040] In the description of the present disclosure, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific situations.

[0041] In the present disclosure, for the convenience of description, the extending direction of the central 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 surrounding the central axis of the annular stator yoke is designated as the circumferential direction.

[0042] The present disclosure provides a stator assembly having a first coil 21 and a second coil 22. The stator assembly includes a stator core 1, and the first coil 21 and the second coil 22 are wound around the stator core 1. Specifically, the stator core 1 of the stator assembly may include 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, and in particular, are evenly spaced apart at equal intervals, thereby leaving a space for winding the first coil 21 and the second coil 22. For example, the number of stator teeth 12 is, for example, Figure 1 12 as shown, but the number of stator teeth in the present disclosure is not limited to 12, and may also be 3, 6, 9, 15, 18, 21, 24, etc. The radially inner top ends of the stator teeth 12 extend at least partially in both circumferential directions to form wire grooves on both circumferential sides, which are convenient for winding and can be used to prevent the coil from detaching.

[0043] The stator core 1 can be made by stamping and stacking 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 sheet can be 0.2 mm - 0.5 mm, preferably, the thickness of the silicon steel sheet can be 0.35 mm.

[0044] In addition, the stator core 1 can also be made by powder metallurgy of soft magnetic composite material (SMC material). The stator core 1 can be integrally formed or 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 equally applicable to the present disclosure.

[0045] The stator assembly according to the present disclosure may further include a stator skeleton 3, which can be axially coated on both sides of the stator core 1 to form wire grooves for accommodating coils on both axial sides of the stator core 1, as Figure 1 and Figure 2 shown. This facilitates the winding of the first coil 21 and the second coil 22, is beneficial to supporting the first coil 21 and the second coil 22, and resists the action of electromagnetic force, preventing short circuits caused by coil deformation and reducing the probability of motor failure.

[0046] The number of windings 2 can be multiple, for example, it can be set to 3, and the three-phase windings 2 are independent of each other and respectively correspond to the three phases of U, V, and W; or it can be set to 2, and the two-phase windings 2 are independent of each other and respectively correspond to two phases. The winding 2 may include at least one first coil 21 and at least one second coil 22, especially including a first coil group formed by connecting a plurality of first coils 21 in series and a second coil group formed by connecting a plurality of second coils 22 in series. The number of the first coils 21 in the first coil group is the same as the number of the second coils 22 in the second coil group. In particular, the first coils 21 in the first coil group and the second coils 22 in the second coil group are wound around the same stator teeth.

[0047] Further, the first coils 21 and the second coils 22 of the three-phase winding 2 are all wound around adjacent stator teeth in a cyclic and alternating manner, that is, the adjacent stator teeth around which the first coils 21 and the second coils 22 of the same-phase winding are wound are separated by two stator teeth. For example, if Figure 1 the 12 stator teeth are sequentially numbered from 1 to 12, then the first coils 21 and the second coils 22 of one-phase winding 2 are wound on the 1st, 4th, 7th, and 10th teeth, the first coils 21 and the second coils 22 of another-phase winding 2 are wound on the 2nd, 5th, 8th, and 11th teeth, and the first coils 21 and the second coils 22 of the remaining one-phase winding 2 are wound on the 3rd, 6th, 9th, and 12th teeth.

[0048] The first coil 21 and the second coil 22 are made of different conductive materials. Specifically, the first coil 21 is made of a first material for conducting electricity, and the second coil 22 is made of a second material for conducting electricity. The price of the first material may be higher than that of the second material. However, some properties of the first material are superior to those of the second material, such as the fatigue resistance, high-temperature resistance, and tensile strength of the first material are better than those of the second material, and the resistivity of the first material is less than that of the second material. The present disclosure aims to use a cheaper but less performant material to reduce the manufacturing cost of the stator assembly. However, if all the materials are replaced with materials having even worse performance, the performance of the stator assembly cannot be guaranteed or the volume of the stator assembly needs to be increased. Therefore, the present disclosure adopts a partial replacement solution. On the premise of ensuring the performance of the stator assembly and not changing the volume of the stator assembly, a cheaper material is used at least partially to reduce the manufacturing cost.

[0049] The above-mentioned first material and second material may refer to elemental metal materials or alloy materials. For example, the first material may be a copper alloy material or pure copper, and the second material may be an aluminum alloy material or pure aluminum. The first coil may be, for example, an enameled copper wire, and the second coil may be, for example, an enameled aluminum wire. Here, the enameled copper wire may be made of pure copper or a copper alloy, and the enameled aluminum wire may be made of pure aluminum or an aluminum alloy.

[0050] Specifically, the stator assembly according to the present disclosure connects the first coil group and the second coil group in parallel. For example, as Figure 3 shown, the stator assembly can also be used in a three-phase circuit. Therefore, the number of windings 2 is set to 3, corresponding to the U phase, V phase, and W phase. Among them, the three-phase windings 2 may be, for example, Y-connected. In each phase of the windings 2, the first coil group and the second coil group are connected in parallel. When the number of winding turns, the rotor, and the rotational speed are determined, the back electromotive force of the motor is determined. Under the condition that the power of the motor remains unchanged, the total current of the motor remains unchanged, and the total torque of the motor remains unchanged. Therefore, this parallel structure is beneficial to reducing the total resistance of the motor windings, thereby reducing the total heat generation of the motor.

[0051] In particular, the winding 2 of the present disclosure is preferably wound around the stator core 1 in a concentrated winding manner, with a simple structure and easy maintenance.

[0052] Furthermore, the present disclosure winds the first coil 21 adjacent to the stator teeth 12, and winds the second coil around the periphery of the first coil 22. For example, as Figure 2As shown, the inner three layers of the coil are the first coil 21, and the outer three layers of the coil are the second coil. The first coil 21 is closer to the stator core 1. Therefore, the magnetic field lines generated by the first coil 21 are all concentrated and conducted through the stator core 1; the second coil 22 is close to the outside of the stator. Only part of the magnetic field lines generated by the second coil 22 are conducted through the stator core 1, and part of the magnetic field lines are magnetically conducted through the air. And the magnetic conductivity of the stator core 1 is much better than that of the air. The magnetic field generated by the first coil 21 located in the inner layer will act on the rotor better.

[0053] On this basis, the present disclosure also sets the wire diameter of the first coil 21 to be larger than that of the second coil 22. Preferably, on each stator tooth, the number of turns of the first coil 21 is approximately the same as that of the second coil 22. In particular, each first coil 21 is the same, and each second coil 22 is the same. Further, in the present disclosure, the resistivity of the first material selected for the first coil 21 is less than the resistivity of the second material selected for the second coil 22. Therefore, on each stator tooth, the total resistance of the first coil 21 is less than the total resistance of the second coil 22. Since the resistance of the first coil 21 is less than that of the second coil 22 on each stator tooth, the current flowing through the first coil 21 is greater than that of the second coil 22, and the magnetic field intensity generated by the first coil 21 is greater than that of the second coil 22. Combining with the magnetic conduction advantage closer to the stator core 1, the torque that the first coil 21 can provide acting on the rotor is greater than that of the second coil 22, that is, the proportion of the torque that the first coil 21 provides acting on the rotor in the total torque is greater 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 the 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 a greater torque than the structure with the second coil arranged in the inner layer and the first coil arranged in the outer layer or the structure with the first coil and the second coil wound mixedly. Thus, it can be realized that when the second coil replaces the first coil, the provided torque will not be significantly reduced, but still can meet the requirements.

[0054] Since the first coil 21 provides the main torque of the motor, the first coil 21 itself will be subject to a greater reaction force. Therefore, in order to prevent short circuits or open circuits caused by the fracture or damage of the first coil 21, 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 properties, so that the first coil 21 can withstand a greater reaction force and is beneficial to providing a greater proportion of the total torque. On the contrary, since the second coil 22 provides less torque, the second material can be subject to less reaction force, and the selection requirements for the second material can be relaxed, and a material with weaker mechanical properties but cheaper price can be selected to reduce the cost.

[0055] Furthermore, since the current flowing through the first coil 21 is greater than that through the second coil 22, and the heat generated is proportional to the square of the current, the influence of current on the generated heat is greater than that of resistance. More heat will be generated in the first coil 21, and less heat will be generated in the second coil 22. Since the first coil 21 is located in the inner circle and heat is less likely to dissipate, the first material selected for the first coil 21 needs to have better heat resistance. On the contrary, since the second coil 22 not only generates less heat but also is located in the outer circle and is more conducive to heat dissipation, 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.

[0056] Furthermore, according to the stator assembly of the present disclosure, the selection of wire diameter and the selection of number of turns affect each other, and the wire diameter can be adjusted according to the motor performance. Under the condition that other conditions remain unchanged in the present disclosure, by selecting different wire diameters, the motor performance can be optimized. Considering the unchanged spacing of the motor wire slots, the thicker the wire diameters of the first coil 21 and the second coil 22, the smaller the total resistance after parallel connection, the less heat is generated, and the better the performance. However, when the wire diameters of the first coil 21 and the second coil 22 increase, the number of turns will decrease, the back electromotive force will decrease, the total current will increase, the heat generation will increase, and the motor performance will deteriorate. Therefore, the selection of the wire diameters of the first coil and the second coil is the result of comprehensive consideration and cannot only consider one factor. Therefore, on the premise of considering the slot fill factor and ensuring that the number of turns is sufficient, the thicker the wire diameters of the first coil and the second coil, the better.

[0057] Therefore, according to the comprehensive consideration result, for 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 that of the second coil 22, and preferably 1.2 times that 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 that of the first coil 21. Preferably, on each stator tooth, the number of turns of the second coil 22 is equal to that 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 that of the second coil 22, and preferably 0.4 times. In particular, each first coil 21 is the same, and each second coil 22 is the same.

[0058] Furthermore, for the stator assembly with both the first coil 21 and the second coil 22, since power needs to be supplied to the first coil 21 and the second coil 22, the first winding 211 (for example, enameled copper wire) of the first coil 21 and the second winding 221 (for example, enameled aluminum wire) of the second coil 22 need to be connected to the terminal.

[0059] 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 of each phase winding 2 and the second winding 221 of the second coil group 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, Figure 6 It shows that the first winding 211 and the second winding 221 are electrically connected to the terminal 4 simultaneously. In particular, they are welded to the terminal 4.

[0060] Figure 7 It shows the welding process of the first winding 211 and the second winding 221 to the terminal 4. For the convenience of welding, nickel or tin is plated on the surface of the terminal. The first winding 211 and the second winding 221 are first positioned at the welding position of the terminal 4. For example, as Figure 7 shown, the terminal 4 includes a wire groove for accommodating the winding, and this wire groove is the welding position. The width of the wire groove 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. This enables the windings in the wire groove to be arranged in a single row, which is beneficial to improving the welding quality.

[0061] The terminal 4, as well as the first winding 211 and the second winding 221, are placed between two electrode rods 6, and the welding process is realized through the electrode rods 6. For example, the terminal is heated to a temperature between 155°C and 180°C, which depends on the heat-resistant temperature grade of the first winding 211 and the second winding 221, to melt the paint on the surfaces of the first winding 211 and the second winding 221, exposing the conductive metal wires inside the first winding 211 and the second winding 221. For example, the copper wire inside the first winding 211 and the aluminum wire inside the second winding 221. The terminal 4 is pressed tightly so that the copper wire and the aluminum wire inside the first winding 211 and the second winding 221 are in full contact with the surface of the terminal 4, and then it is cooled. After cooling, the molten paint solidifies, re-coating the copper wire, the aluminum wire, and the terminal 4 to complete the welding.

[0062] The number of terminals 4 can be three, corresponding to the three-phase windings 2 respectively, so that each phase winding 2 is connected to one terminal 4 respectively. Terminal slots can be reserved on the stator skeleton 3 for the terminals 4 to be inserted and positioned therein. As Figure 8 shown, the terminal 4 can be arranged on one side in the axial direction of the stator core 1, and this terminal 4 has a free end extending away from the stator core 1.

[0063] Furthermore, in order to protect the electrical connection parts and the coils, the stator assembly further includes a plastic encapsulation part 5. For example, after welding, the entire stator assembly is plastic encapsulated with BMC material. In particular, the electrical connection parts (such as the welding parts) between the terminals 4 and the first windings 211 of the first coil group and the second windings 221 of the second coil group are encapsulated, and the first coil 21 and the second coil 22 are encapsulated, as Figure 9 shown. Thereby, air is isolated, preventing the coils from oxidizing, preventing electrochemical reactions between the first winding and the second winding (such as copper wire and aluminum wire), reducing corrosion. In addition, physical protection can also be provided, so that the first coil and the second coil are further fixed, reducing the vibration of the coils during the operation of the motor.

[0064] As Figure 10 shown, the free ends of the terminals 4 are exposed outside the plastic encapsulation part 5 for subsequent wiring processes. For example, three terminals 4 can be arranged at adjacent stator teeth to facilitate simplifying the plastic encapsulation.

[0065] The present disclosure also proposes a motor, which includes the above-mentioned stator assembly.

[0066] Through actual experimental tests on a fully copper-wound motor and the motor according to the present disclosure (such as a copper-aluminum wire-wound motor), when the torque is the same, the difference in efficiency between the two motors is between 0.58% and 1.05%.

[0067] The test conditions are as follows:

[0068]

[0069] From Figure 4 , Figure 5 it can be seen that at the same torque, the efficiency of the copper wire motor is better than that of the motor according to the present disclosure, and the difference in efficiency between the two is between 0.20% and 1.37%. Among them, the efficiency difference is the largest at 1.37% when the torque is 100 N·m, and the smallest at 0.20% when the torque is 20 N·m.

[0070] Under the test conditions of this patent, for a φ260 motor with a full-load output power of 15 kW, its corresponding torque is 95.5 N·m. From Figure 5It can be seen that between 10 N·m and 80 N·m, the difference in efficiency between the copper wire motor and the motor of the present disclosure is basically controlled within 0.7%. The difference in efficiency between the two only starts to increase significantly when approaching the full load output power. Referring to the energy efficiency grade of the variable frequency drive permanent magnet synchronous motor in GB30253-2013, the motor of the present disclosure meets the first-level energy efficiency standard between 20 N·m and 80 N·m, that is, when the power is between 3.1 kW and 12.6 kW. Generally, the motor will not operate at full load all the time. Although the efficiency of the motor of the present disclosure is less than that of the copper wire motor, the motor of the present disclosure can meet the first-level energy efficiency within a quite wide power output range, and by replacing half of the expensive first material (such as copper) with the second material (such as aluminum), the cost will be greatly reduced under the condition that the service life and the stator volume remain unchanged.

[0071] It should be understood that the above description is intended to illustrate and not to limit. For example, the above embodiments (and / or aspects thereof) can be used in combination with each other. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the scope of the present disclosure. The functions or performances of the various elements or modules described herein are for illustrative purposes only and are in no way restrictive, but are merely exemplary embodiments. After reading the above description, many other embodiments and modifications within the spirit and scope of the claims will be apparent to those skilled in the art. Therefore, the scope of the present disclosure should be determined with reference to the appended claims and the full scope of equivalents given by these claims.

[0072] In the appended claims, the terms "comprising" and "wherein" are used as simple English equivalents of the corresponding terms "including" and "in which". Additionally, in the following claims, the terms "first", "second", "third", etc. are used only as labels and are not intended to impose numerical requirements on their objects.

Claims

1. A stator assembly, characterized in that: include a stator core including an annular stator yoke and a plurality of stator teeth connected to a radial inner side of the stator yoke, the plurality of stator teeth being spaced apart from each other in a circumferential direction, A three-phase winding, each phase winding comprises a first coil group and a second coil group connected in parallel, the first coil group comprises at least one first coil, the second coil group comprises at least one second coil, each of the stator teeth is wound with one of the first coils and one of the second coils, and the first coil of the first coil group and the second coil of the second coil group of each phase winding are wound on the same stator tooth, Each first coil is wound around a corresponding stator tooth, each second coil is wound around a corresponding first coil, the first coil includes a conductive first material, the second coil includes a conductive second material, the resistivity of the first material is less than the resistivity of the second material, and the total resistance of the first coil group of each phase winding is less than the total resistance of the second coil group.

2. The stator assembly according to claim 1, characterized in that A ratio of a total resistance of the first coil group to a total resistance of the second coil group of each phase winding is in a range of 0.3 to 0.

5.

3. The stator assembly according to claim 2, characterized in that: A ratio of a total resistance of the first coil group to a total resistance of the second coil group of each phase winding is 0.

4.

4. The stator assembly according to claim 2, characterized in that: On each stator tooth, a ratio of the number of turns of the second coil to the number of turns of the first coil is in a range of 0.8 to 1.

2.

5. The stator assembly according to claim 4, characterized in that: On each stator tooth, the number of turns of the second coil is equal to the number of turns of the first coil.

6. The stator assembly according to claim 1, characterized in that The stator assembly further includes a stator frame, which covers both sides of the stator core in the axial direction and forms wire slots for accommodating the first coil and the second coil on both sides of the stator teeth in the axial direction.

7. The stator assembly according to claim 1, characterized in that: The windings are arranged in the manner of concentrated windings.

8. The stator assembly according to claim 7, characterized in that The connection type of the winding is Y-type connection.

9. The stator assembly according to any one of claims 1 to 8, characterized in that: The first coil is made of enameled copper wire, and the second coil is made of enameled aluminum wire.

10. The stator assembly according to any one of claims 1 to 8, characterized in that: The first coil group includes a plurality of first coils connected in series, and the second coil group includes a plurality of second coils connected in series.

11. A motor, characterized in that: include A stator assembly according to any one of claims 1 to 10.

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