Stator, rotor, electric motor, and electric device comprising electric motor

Abstract

The present disclosure relates to a stator, a rotor, an electric motor, and an electric device comprising the electric motor. The stator comprises: a stator core comprising a plurality of stator teeth arranged in a spaced apart manner, wherein a stator slot is formed between two adjacent stator teeth, and the stator slot comprises a first slot wall associated with a first stator tooth among the two adjacent stator teeth, and a second slot wall associated with a second stator tooth among the two adjacent stator teeth; a stator winding disposed around the stator teeth, and at least a portion of the stator winding being disposed within the stator slot, the stator winding comprising two or more stacked coils, each of the two or more coils comprising, within the stator slot: a first edge abutting one of the first slot wall or the second slot wall; a second edge facing away from one of the first slot wall or the second slot wall; and a portion positioned between the first edge and the second edge and having a cross-section, wherein at least two coils of the two more coils have different cross-sections.

Description

Stator, rotor, electric motor and electrically powered device comprising the electric motor TECHNICAL FIELD

[0001] The present disclosure relates to the field of electric motors, and more specifically, the present disclosure relates to a stator, a rotor, an electric motor comprising the same, and an electrically powered device comprising the electric motor. BACKGROUND

[0002] An electric motor is a device capable of converting electrical energy into mechanical energy. An electric motor generally comprises a stator and a rotor. The stator and the rotor usually comprise a core comprising teeth and slots formed between the teeth. Windings are disposed in the slots and around the teeth. The electric motor generates a rotating magnetic field using the energized coils (stator windings) and acts on the rotor to form a magnetic electric power rotating torque.

[0003] The slot fill factor of an electric motor is an important parameter reflecting the performance of the electric motor. The slot fill factor refers to the ratio of the conductor cross-sectional area in the core slot to the total area of the core slot. The higher the slot fill factor of the electric motor, the more filled the wire is in the core slot. Under the condition of meeting the safety requirements, the high or low of the slot fill factor determines the strength of the electric field, the higher the slot fill factor, the higher the efficiency of the electric motor. Therefore, how to improve the slot fill factor of the electric motor is a problem concerned in the field.

[0004] SUMMARY

[0005] Some embodiments of the present disclosure provide a stator comprising: a stator core comprising a plurality of spaced apart stator teeth, a stator slot being formed between two adjacent stator teeth, the stator slot comprising a first slot wall associated with a first stator tooth of the two adjacent stator teeth and a second slot wall associated with a second stator tooth of the two adjacent stator teeth; and a stator winding disposed around the stator teeth and at least a portion of the stator winding is disposed in the stator slot, the stator winding comprising two or more stacked coils, each of the two or more coils comprising, in the stator slot: a first edge abutting one of the first slot wall or the second slot wall; a second edge distal from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross section, wherein the cross section of at least two of the two or more coils are different.

[0006] Some embodiments of the present disclosure provide a rotor, comprising: a rotor core comprising a plurality of spaced-apart rotor teeth, a rotor slot being formed between two adjacent rotor teeth, the rotor slot comprising a first slot wall associated with a first one of the two adjacent rotor teeth, and a second slot wall associated with a second one of the two adjacent rotor teeth; and a rotor winding disposed around the rotor teeth, at least a portion of the rotor winding being disposed within the rotor slot, the rotor winding comprising two or more stacked coils, each of the two or more coils comprising, within the rotor slot: a first edge abutting one of the first slot wall or the second slot wall; a second edge distal from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross-section, wherein the cross-sections of at least two of the two or more coils are different.

[0007] Some embodiments of the present disclosure provide an electric motor, comprising a stator as any of the embodiments of the present disclosure; and / or a rotor as any of the embodiments of the present disclosure.

[0008] Some embodiments of the present disclosure provide an electric device, comprising an electric motor as any of the embodiments of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to further clarify the embodiments of the present disclosure, a specific description of the embodiments of the present disclosure will be presented with reference to the accompanying drawings. It should be understood that these drawings only depict some embodiments of the present disclosure and therefore are not to be considered as limiting the scope of the present disclosure.

[0010] In the drawings, the main connection relationship or relative position relationship of various components is shown, rather than all of these relationships, and the components in the drawings and the connections are not necessarily drawn in accordance with the actual proportions.

[0011] FIG. 1A shows a cross-sectional view of a wire arrangement in a wire slot of a round wire motor according to the prior art;

[0012] FIG. 1B shows a cross-sectional view of a wire arrangement in a wire slot of a flat wire motor according to the prior art;

[0013] FIG. 1C shows a cross-sectional view of another wire arrangement in a wire slot according to the prior art;

[0014] FIG. 2A shows a perspective view of a stator according to some embodiments of the present disclosure;

[0015] FIG. 2B shows a perspective view of a core of a stator according to some embodiments of the present disclosure;

[0016] FIG. 3 illustrates a cross-sectional view of a stator perpendicular to the center axis of the stator in FIG. 2A, according to some embodiments of the present disclosure;

[0017] FIG. 4A illustrates a perspective view of a single coil, according to some embodiments of the present disclosure;

[0018] FIG. 4B illustrates a portion of a perspective view of a single coil including a connection having a bent portion, according to some embodiments of the present disclosure;

[0019] FIG. 5 illustrates a cross-sectional view of a portion of a stator, according to some embodiments of the present disclosure;

[0020] FIG. 6 illustrates a perspective view of a wound stator winding in FIG. 5, according to some embodiments of the present disclosure;

[0021] FIG. 7 illustrates a cross-sectional view of a portion of a stator, according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0022] The following description refers to the accompanying drawings. The drawings show, by way of example, some embodiments that can be practiced. It is to be understood that the embodiments are merely examples and are not intended to limit the scope of the claimed subject matter. Those skilled in the art will readily recognize a variety of modifications and adaptations of the disclosed embodiments that can be made without departing from the scope of the claimed subject matter.

[0023] Unless defined otherwise, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0024] The terms “first,” “second,” “third,” “fourth,” and the like in the specification and in the claims, unless otherwise specified, do not imply any order, quantity, or importance, but are merely used to distinguish one component from another.

[0025] Embodiments of the present application are exemplary implementations or examples. References in the specification to “an embodiment,” “one embodiment,” “some embodiments,” “an alternate embodiment,” or “other embodiments” indicate that the alternative is included in at least one embodiment of the technology, but not necessarily all embodiments. Various appearances of “an embodiment,” “one embodiment,” or “some embodiments” do not necessarily all refer to the same embodiments. Elements or aspects from one embodiment can be combined with elements or aspects from another embodiment.

[0026] In the description of the disclosure, the terms "upper", "lower", "top", "bottom", "left", "right", "vertical", "horizontal" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the disclosure, and do not indicate or imply that the devices or components referred to must have a particular orientation, or be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the disclosure. In other embodiments in which the placement direction of the device or component is opposite or different from the direction shown in the figure, these positional descriptions can be changed accordingly.

[0027] In the description of the disclosure, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0028] In the description of the disclosure, the term "connection" can include electrical or mechanical connection, and can include direct or indirect connection.

[0029] As described above, the slot fill factor is an important parameter of the motor. Under the premise of ensuring safety (for example, considering the heat generated by the conduction of the coil and other problems), it is desirable to improve the slot fill factor. In the prior art, one way to improve the slot fill factor is to place as many turns as possible in the core slot. For example, for the wire slot of the round wire motor as shown in FIG. 1A, the slot fill factor can be improved by changing the arrangement of the round wire. However, due to the inevitable gap between each round wire, the effect of this method is limited.

[0030] Another way to improve the slot fill factor is to change the shape of the wire to reduce the space in the wire slot that is not occupied by the wire as much as possible. For example, by changing the round wire into a rectangular, parallelogram, trapezoidal or other shaped wire to form a more dense space arrangement than the round wire, thereby reducing the space interval in the wire slot. For example, for a rectangular core slot, this method can indeed improve the slot fill factor. However, for non-rectangular wire slots, as shown in FIG. 1B, this method will inevitably cause space waste in the wire slot, especially in the middle part.

[0031] To solve the above problems, for the case of a trapezoidal slot for example, one solution is to form the coil also correspondingly into a whole continuous trapezoidal shape (which is similar to a spring structure along the axial direction), the cross section of such coil continuously changes along the trapezoidal shape. However, such continuously variable cross section coil can require the use of expensive production processes (for example, three-dimensional printing technology) to form, resulting in a significant increase in product cost. In addition, another problem of using continuous variable cross section technology is that due to the limited size of the slot opening (such as the slot opening below the wire slot shown in FIG. 1A or FIG. 1B), when another integrally formed coil is to be placed on the right side after the left side of the integrally formed coil is placed in place, for example, since the part of the integrally formed coil close to the bottom of the slot can be larger than the size of the slot opening left (i.e. the space left after the coil placed on the left side occupies), the right side coil can not be able to be fitted onto the tooth directly at the slot opening, thereby greatly reducing the producibility.

[0032] Another conventional method is shown in FIG. 1C, which stacks multiple coils of the same winding in the slot, and each layer can include a different number of turns. However, on the one hand, since the length of the inner coil winding (closer to the winding of the stator tooth, for example) is smaller than the length of the outer coil winding, the resistance of the inner coil winding is lower than that of the outer coil winding, and thus once connected in parallel, the current imbalance in these parallel windings occurs, resulting in uneven temperature rise and high temperature hot holes, thereby reducing the overall power and efficiency of the motor. On the other hand, in this method, the connection part (also known as the tap) of the winding can be connected out of the outermost winding, and the others are buried inside the winding, which cannot be effectively connected out, thereby cannot be conveniently connected in series and parallel. On the other hand, in the case of using liquid cooling or oil cooling in the slot, most of the windings cannot be in contact with the liquid cooling medium, only the part of the winding close to the central area can be cooled, while the part of the winding close to the stator tooth with higher temperature cannot be in contact with the cooling medium, thus cannot be effectively cooled, and there are also adverse effects on efficiency and the like caused by uneven heating.

[0033] To solve one or more of the above technical problems and / or other technical problems that can exist, the present disclosure proposes a stator, a rotor, an electric motor comprising the same, and an electric device comprising the electric motor.

[0034] Some embodiments of the present disclosure can include a stator comprising: a stator core comprising a plurality of spaced apart stator teeth, a stator slot formed between two adjacent stator teeth, the stator slot comprising a first slot wall associated with a first stator tooth of the two adjacent stator teeth, and a second slot wall associated with a second stator tooth of the two adjacent stator teeth; and a stator winding disposed around the stator teeth, and at least a portion of the stator winding is disposed within the stator slot, the stator winding comprising two or more stacked coils, each of the two or more coils comprising, within the stator slot: a first edge against one of the first slot wall or the second slot wall; a second edge away from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross section, wherein the cross section of at least two of the two or more coils is different.

[0035] Some embodiments of the present disclosure can include a rotor comprising: a rotor core comprising a plurality of spaced apart rotor teeth, a rotor slot formed between two adjacent rotor teeth, the rotor slot comprising a first slot wall associated with a first rotor tooth of the two adjacent rotor teeth, and a second slot wall associated with a second rotor tooth of the two adjacent rotor teeth; and a rotor winding disposed around the rotor teeth, and at least a portion of the rotor winding is disposed within the rotor slot, the rotor winding comprising two or more stacked coils, each of the two or more coils comprising, within the rotor slot: a first edge against one of the first slot wall or the second slot wall; a second edge away from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross section, wherein the cross section of at least two of the two or more coils is different.

[0036] Some embodiments of the present disclosure can include an electric motor comprising a stator and a rotor, wherein the stator comprises a stator according to any embodiment of the present disclosure; and / or the rotor comprises a rotor according to any embodiment of the present disclosure.

[0037] Some embodiments of the present disclosure can also include an electric device, which can comprise an electric motor according to any embodiment of the present disclosure.

[0038] FIG. 2A shows a perspective view of a stator 10, according to some embodiments of the present disclosure. As shown in FIG. 2A, the stator 10 can comprise a stator core 12 and a stator winding 14.

[0039] FIG. 2B illustrates a perspective view of the stator core 12 of the stator 10, in accordance with some embodiments of the present disclosure. In some embodiments, the stator core 12 can include an iron core. The stator core 12 can include a plurality of spaced apart stator teeth 122-1, 122-2,..., 122-n (which can be collectively referred to herein as stator teeth 122). A stator slot 124 can be formed between two adjacent stator teeth 122. For example, as shown in FIG. 2B, a stator slot 124 can be formed between the stator tooth 122-1 and the stator tooth 122-2. The stator slot 124 can include a first slot wall 123 associated with one of the two adjacent stator teeth (e.g., one of the stator tooth 122-1 or the stator tooth 122-2), and a second slot wall 125 associated with the other of the two adjacent stator teeth (e.g., the other of the stator tooth 122-1 or the stator tooth 122-2).

[0040] Referring back to FIG. 2A, the stator 10 can also include a stator winding 14. The stator winding 14 is disposed around the stator teeth 122. As described above, in some embodiments of the present disclosure, the stator core 12 can include a plurality of spaced apart stator teeth 122-1, 122-2,..., 122-n. Accordingly, the stator 10 can include a plurality of stator windings 14 that are respectively wound around respective ones of the plurality of stator teeth 122. As shown in FIG. 2A, at least a portion of the stator winding 14 is disposed within the stator slot 124.

[0041] FIG. 3 illustrates a cross-sectional view of the stator 10 taken perpendicular to the central axis 11 of the stator 10 of FIG. 2A, in accordance with some embodiments of the present disclosure. As shown in FIG. 3, in some embodiments of the present disclosure, the stator winding 14 can include two or more stacked coils. By way of example and not limitation, FIG. 3 illustrates that the stator winding 14 includes three stacked coils 142, 144, and 146. In other embodiments of the present disclosure, the stator winding 14 can include two or more than three coils.

[0042] As shown in FIG. 3, in some embodiments of the present disclosure, each of the two or more coils can include, within the stator slot 124, a first edge abutting against one of the first slot wall 123 or the second slot wall 125 (e.g., the first slot wall 123, or the second slot wall 125), such as the first edge 141 of the coil 142 shown in FIG. 3. Each of the coils can also include, within the stator slot 124, a second edge 143 away from the aforementioned one of the first slot wall or the second slot wall (e.g., the same first slot wall 123 or the second slot wall 125 as the aforementioned). Each of the coils can also include a portion between the first edge 141 and the second edge 143, which has a predetermined cross section between the first edge 141 and the second edge 143, i.e., the cross section shown in FIG. 3. In the case where each of the coils has multiple turns, the cross section can refer to the cross section of each turn. For example, as shown in FIG. 3, the coil 142 has five turns, each of which has a cross section. In some embodiments, the cross section of each turn of the same coil can be set to be the same or at least a portion of the turns have the same cross section.

[0043] In embodiments of the present disclosure, the cross sections of the at least two coils within the stator slot 124 are set to be different. For example, as an example but not limitation, as shown in FIG. 3, the cross sections of the coil 142 and the coil 144 are set to be different, and / or further the cross section of the coil 146 is set to be different from both the coil 142 and the coil 144. The technology of the present disclosure can increase the slot fill factor of the coils within the stator slot 124, and thus improve the working efficiency, by setting the coil winding to include two or more coils with different cross sections, and arranging the two or more coils according to the shape of the stator slot 124.

[0044] In some embodiments, the difference in the cross sections can include a difference in the shape of the cross sections. For example, in some embodiments, the cross section of a coil can be set to have a shape of a substantially rectangular (e.g., a rectangle, a rounded rectangle) shape with a length (the dimension between the first edge 141 and the second edge 143) and a width (the dimension of each turn of the coil along the edge 141), and the length of the cross section of the two or more coils can be set to be at least different to achieve the difference in the shape of the cross sections. In some embodiments, the shape of the cross section of the two or more coils can also be set to be different, but the area is set to be the same. For example, the coil 142 can have a cross-sectional area a*b (where a can represent the length and b can represent the width), the coil 144 can have a cross-sectional area c*d (where c can represent the length and d can represent the width), a*b = c*d, but a≠c. In embodiments of the present disclosure, the resistance of each turn winding can be ensured to be the same by adjusting the cross-sectional area of the coil, so that multiple windings can be achieved in parallel on a single tooth, and at the same time these windings will not cause the problem that the current is unevenly distributed in these parallel windings due to the difference in resistance.

[0045] In some embodiments, the stator slots 124 can include non-rectangular stator slots 124. For example, as an example, the size of the slot opening is smaller than the size of the slot bottom, i.e., as shown in FIG. 3, the distance between the first slot wall 123 and the second slot wall 125 at the slot opening is smaller than the distance between the first slot wall 123 and the second slot wall 125 at the slot bottom. In these specific embodiments, the coils near the slot bottom can be arranged to have a larger length than the coils near the slot opening, so as to make full use of the space in the slot to arrange the windings, and improve the slot fill factor.

[0046] In some embodiments of the present disclosure, the two or more coils described above can be disconnected from each other. In some other embodiments of the present disclosure, the two or more coils described above can be connected end to end to form a continuous winding. In some embodiments, the coils in the present disclosure can include copper coils.

[0047] In some embodiments of the present disclosure, each of the two or more coils included in the stator winding 14 can include one or more layers of structure (i.e., multiple turns) around the corresponding stator tooth 122. In some embodiments of the present disclosure, at least one of the two or more coils included in the stator winding 14 includes a multi-layer structure (i.e., multiple turns) around the corresponding stator tooth 122. For a single coil, the multi-layer structure of the coil can be integrally formed to form a continuous electrical connection and mechanical connection inside. The outer surface of the multi-layer structure of the coil can be arranged to be electrically isolated, for example, coated with an insulating layer, so that when the multi-layer structure of the coil is stacked together, electrical isolation is formed between different layers. Each layer of the multi-layer structure of the same coil can have the same cross section, or at least a portion of the multi-layer structure has the same cross section.

[0048] In some embodiments of the present disclosure, two adjacent coils of the two or more coils in the same winding can be connected through a connecting portion. The connecting portion is not coated with an insulating layer, so that the two coils can be electrically connected through the connecting portion. The connecting portion can be arranged outside the stator slot 124, so that the coil stack inside the stator slot 124 is more compact, and the slot fill factor is improved. In addition, the connecting portion of the winding in the present disclosure arranged outside the stator slot 124 can be very convenient to be connected out for various series and parallel combinations.

[0049] In some embodiments, the above-mentioned stator 10 of the present disclosure can be applied to an electric machine. The electric machine can include a lamination electric machine. Each turn of the winding around the stator and / or the rotor in the lamination electric machine can include a lamination shape around the stator or the rotor. In some embodiments, in the winding 14 including two or more coils, each coil can include a multi-layer lamination shape. For the same coil, the size of the lamination shape can be the same.

[0050] With continued reference to FIG. 3, in some embodiments of the present disclosure, a stator slot 124 can include a first stator winding 14-1 and a second stator winding 14-2. The first stator winding 14-1 can be associated with the first slot wall 123. The second stator winding 14-2 can be associated with the second slot wall 125. Each of the first stator winding 14-1 and the second stator winding 14-2 can include two or more coils of any of the embodiments above. As shown in FIG. 3, in some embodiments, the first stator winding 14-1 and the second stator winding 14-2 are symmetrically arranged within the same stator slot 124.

[0051] The technology of the present disclosure can greatly improve the slot fill factor while facilitating manufacturing. It can be appreciated that there can still be some gaps in the discrete (stepped) varying cross-section winding or between different windings. In some embodiments of the disclosure, a cooling fluid can be included in the gaps inside the stator slot 124, i.e., the cooling fluid is used to fill the gaps inside the stator slot 124 to cool the coil windings that generate heat after being energized, thereby improving the service life and safety. In some embodiments, the cooling fluid can include oil. In addition, in the scheme of the present disclosure, each layer of winding (e.g., each copper sheet) can be in contact with the cooling fluid, thereby being able to more fully and uniformly cool all the copper sheet windings in the slot without causing one or more problems due to uneven temperature.

[0052] In addition, when placing the coil windings into the stator slot, the coil with a larger bottom cross-sectional length can be placed first from the slot opening position, and then other coils can be placed in order according to the length of the cross-section, so that the production and manufacturing of the present disclosure is more convenient and has lower cost.

[0053] FIG. 4A shows a perspective view of a single coil 148 according to some embodiments of the present disclosure. The coil 148 in FIG. 4A can be the coil 142, the coil 144, or the coil 146 in FIG. 3, or any other coil in the present disclosure. In the embodiment shown in FIG. 4A, the coil 148 includes several layers of structure for the purpose of illustration. However, in some other embodiments, the coil 148 can include a different number of layers than shown in FIG. 4A, including one layer or other numbers of multiple layers.

[0054] As shown in FIG. 4A, the coil 148 can be a multi-layer structure that is integrally formed. Each layer of the structure can include a racetrack shape. As shown in FIG. 4A, the racetrack shape can include an elongated portion that is disposed at least partially in the stator slot 124, and an arcuate portion that is disposed outside of the stator slot 124. In some embodiments of the disclosure, a connection portion for connecting two adjacent coils of the two or more coils can be disposed on the arcuate portion. In some alternative embodiments, a connection portion for connecting two adjacent coils of the two or more coils can be disposed outside of the arcuate portion. As shown in FIG. 4A, the connection portion can be disposed on an extension portion 148-1 that extends from the elongated portion to outside of the arcuate portion, or on an extension portion 148-2 that extends from the arcuate portion to outside of the arcuate portion.

[0055] In some embodiments, the connection portion of the two adjacent coils can be formed by a bending (e.g., a zigzag bending) of the arcuate portion of at least one of the coils. In other embodiments, the connection portion of the two adjacent coils can be formed by a bending of the extension portion 148-1 (e.g., the dashed box in FIG. 4B shows a bent portion of the extension portion 148-1) or the extension portion 148-2 of at least one of the coils. In other words, the connection portion can include a bent portion of the arcuate portion, the first extension portion, or the second extension portion of one of the two adjacent coils that is formed by a bending. Forming the electrical connection with the bent portion that is located outside of the racetrack shape can form a connection misalignment on the side, which can further increase the stacking density between the coils, making the structure more stable and improving the slot fill factor.

[0056] The middle layers of the multi-layer racetrack can be the same. The top layer of the multi-layer racetrack (e.g., the topmost layer of the coil 148 shown in FIG. 4A) can include the extension portion 148-1 that extends from the elongated portion to outside of the arcuate portion of the racetrack, or the extension portion 148-2 that extends from the arcuate portion to outside of the arcuate portion of the racetrack (not shown in FIG. 4A). Similarly, the bottom layer of the multi-layer racetrack (e.g., the bottommost layer of the coil 148 shown in FIG. 4A) can include the extension portion 148-1 that extends from the elongated portion to outside of the arcuate portion of the racetrack (shown in FIG. 4A), or the extension portion 148-2 that extends from the arcuate portion to outside of the arcuate portion of the racetrack.

[0057] The top layer of the multi-layered track can include an extension 148-1 extending from the elongated portion of the track to outside of the arcuate portion for forming the first connection portion, and the bottom layer of the multi-layered track can include an extension 148-2 extending from the arcuate portion of the track to outside of the arcuate portion for forming the second connection portion, or vice versa. In other words, the top layer and the bottom layer of the multi-layered track can include extensions extending from different portions (the elongated portion, the arcuate portion). Such a setup can have multiple advantages: on one hand, it can facilitate the stacking between adjacent coils to reduce the gap due to the stacking; on the other hand, it can form an integer number of turns for one coil; on the other hand, it is more convenient to manufacture and more convenient to connect with adjacent coils or other components, respectively. For example, a coil stacked above coil 148 (if present) can be connected with extension 148-1 (extending from the elongated portion) of coil 148 through an extension extending from the arcuate portion of the bottom layer. A coil stacked below coil 148 (if present) can be connected with extension 148-2 (extending from the arcuate portion) of coil 148 through an extension extending from the elongated portion of the top layer. It should be understood that the above descriptions of “top”, “bottom”, “above”, “below”, etc. are in reference to coil 148 of FIG. 4A and are not a limitation.

[0058] In some embodiments of the present disclosure, the connection portion of two adjacent coils can be formed by one or a combination of welding, sintering, or bonding.

[0059] FIG. 5 shows a cross-sectional view of a portion of stator 10 according to some embodiments of the present disclosure. The stator winding associated with one of the first slot wall 123 or the second slot wall 125 in the above can include two or more stator windings (hereinafter referred to as two or more parallel spaced windings) wound in parallel spaced relation around the corresponding stator, which are electrically isolated from each other. For example, FIG. 5 shows two stator windings 14-3 and 14-4 associated with the first slot wall 123 of stator slot 124. The two stator windings 14-3 and 14-4 are wound in parallel spaced relation and are electrically isolated from each other. An embodiment of two parallel spaced windings 14-3 and 14-4 is shown in FIG. 5. However, in other embodiments, there can be more parallel spaced windings. In addition, FIG. 5 shows that the two parallel spaced windings 14-3 and 14-4 have substantially the same number of turns. However, in other embodiments, the stator windings 14-3 and 14-4 can have different numbers of turns.

[0060] Each of the stator windings 14-3 and 14-4 can include two or more coils according to any embodiment of the present disclosure, for example, can include two or more coils connected head to tail with different cross sections as described above in connection with FIGS. 2A-3. Therefore, the same features of each of the stator windings 14-3 and 14-4 as described above will not be repeated here, but the differences and the relationship between the stator windings 14-3 and 14-4 will be mainly described.

[0061] Each of the two or more coils included in each of the stator windings 14-3 and 14-4 can include one or more layers, for example, the same or similar multi-layer racetrack shape as described above. When each coil includes multiple layers, the multiple layers of each coil do not contact each other, but have a gap for the multiple layers of the other stator winding to be respectively inserted and stacked with the multi-layer structure of the other stator winding, as shown in connection with FIG. 5.

[0062] As in the non-limiting embodiment shown in FIG. 5, the stator winding 14-3 can include three coils with different cross sections, and the stator winding 14-4 can also include three coils with different cross sections. The first coil (the coil close to the slot bottom) of the stator winding 14-3 can have the same size of the first cross section as the first coil (the coil close to the slot bottom) of the stator winding 14-4. Similarly, the third coil (the coil close to the slot opening) of the stator winding 14-3 can have the same size of the third cross section as the third coil (the coil close to the slot opening) of the stator winding 14-4. The second coil (the middle coil) of the stator winding 14-3 can have the same size of the second cross section as the second coil (the middle coil) of the stator winding 14-4.

[0063] Similar to the above embodiments, the two adjacent coils of the two or more coils in each stator winding 14-3 or 14-4 can be connected by a connection portion. The connection portion can be arranged according to any of the above embodiments.

[0064] FIG. 6 shows a perspective view of the parallel wound stator windings in FIG. 5 according to some embodiments of the present disclosure. In some embodiments of the present disclosure, the connection portion of the stator winding 14-3 can be arranged on the first side 147. The connection portion of the stator winding 14-4 can be arranged on the second side 149, which is different from the first side 147, for example, the second side 149 can be opposite to the first side 147. In this way, the connection of the two parallel wound windings can be facilitated and the insulation distance between the two parallel wound windings can be ensured, and the stacking of the coils in the parallel wound windings can be made more compact, thereby improving the structural stability and the slot fill factor can be improved.

[0065] In some embodiments of the disclosure, only non-consequent stator windings can be included in each stator slot 124. In other embodiments of the disclosure, only consequent stator windings can be included in each stator slot 124, as shown in the left stator slot 124 in FIG. 5. In yet other embodiments of the disclosure, a combination of consequent stator windings and non-consequent stator windings can be included in each stator slot 124, as shown in the right stator slot 124 in FIG. 5.

[0066] The stator 10 can include a plurality of stator slots 124. In some embodiments of the disclosure, all of the plurality of stator slots 124 can include only non-consequent stator windings. In other embodiments of the disclosure, all of the plurality of stator slots 124 can include only consequent stator windings. In yet other embodiments of the disclosure, at least one of the plurality of stator slots 124 includes a combination of non-consequent stator windings and consequent stator windings.

[0067] In some embodiments of the disclosure, the stator winding 14-3 and the stator winding 14-4 in the consequent stator windings can be configured to be connected. In other embodiments of the disclosure, the stator winding 14-3 and the stator winding 14-4 in the consequent stator windings can be configured to be disconnected from each other. The connection status of the stator winding 14-3 and the stator winding 14-4 can be changed using, for example, a switch. In some embodiments, when the stator winding 14-3 and the stator winding 14-4 in the consequent stator windings are connected, they can be used, for example, to form a phase winding. In other embodiments, when the stator winding 14-3 and the stator winding 14-4 in the consequent stator windings are disconnected from each other, they can form separate circuits and be used to connect different components. For example, as a non-limiting example, when the stator is used in an electric device (e.g., an electric vehicle), the disconnected stator winding 14-3 and the stator winding 14-4 can form a transformer of a charger in a charging mode, for example, as a primary winding and a secondary winding of the transformer, respectively.

[0068] FIG. 7 shows a cross-sectional schematic view of a portion of a stator 10, according to some embodiments of the disclosure. In some embodiments of the disclosure, the stator 10 can include a plurality of stator teeth 122, including, for example, stator teeth 122-1, 122-2, 122-3, etc. shown in FIG. 7. A non-consequent stator winding can be wound on a first stator tooth 122-1 of the plurality of stator teeth 122. A consequent stator winding can be wound on a second stator tooth 122-2 of the plurality of stator teeth adjacent to the first stator tooth 122-1. A third stator tooth 122-3 of the plurality of stator teeth adjacent to the second stator tooth 122-2 and different from the first stator tooth 122-1 can be wound with a consequent stator winding. In embodiments with a number of stator teeth that is a multiple of 3, each group of three stator teeth can be arranged in the above-described configuration in turn.

[0069] The design of the present application has been described above mainly in connection with a stator 10. However, it should be appreciated that the design of the present application can also be applied in a rotor. Accordingly, the present application also provides a rotor comprising: a rotor core comprising a plurality of spaced apart rotor teeth, between which two adjacent rotor teeth a rotor slot is formed, the rotor slot comprising a first slot wall associated with a first one of the two adjacent rotor teeth and a second slot wall associated with a second one of the two adjacent rotor teeth; and a rotor winding arranged around the rotor teeth and at least a portion of which is arranged within the rotor slot, the rotor winding comprising two or more coils stacked, each of the two or more coils comprising within the rotor slot: a first edge against one of the first slot wall or the second slot wall; a second edge away from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross-section, wherein the cross-sections of at least two of the two or more coils are different.

[0070] For ease of description, the technology of the present application has been described herein mainly in connection with a stator 10. However, the design according to any of the embodiments herein can also be applied in a rotor. A rotor according to the present disclosure can also comprise features based on any of the various winding embodiments described in connection with the stator, which are not repeated here.

[0071] The present disclosure also provides an electric motor, which can comprise a stator according to any of the embodiments herein and / or a rotor according to any of the embodiments.

[0072] The present disclosure also provides an electrically powered device, which can comprise but is not limited to an electric vehicle or the like. The electrically powered device can comprise an electric motor according to any of the embodiments of the present disclosure.

[0073] The following are some examples according to the present disclosure.

[0074] Example 1. A stator, the stator comprising:

[0075] a stator core comprising a plurality of spaced apart stator teeth, between which two adjacent stator teeth a stator slot is formed, the stator slot comprising a first slot wall associated with a first one of the two adjacent stator teeth and a second slot wall associated with a second one of the two adjacent stator teeth; and

[0076] a stator winding arranged around the stator teeth and at least a portion of which is arranged within the stator slot, the stator winding comprising two or more coils stacked, each of the two or more coils comprising within the stator slot:

[0077] a first edge abutting one of the first slot wall or the second slot wall;

[0078] a second edge distal from the one of the first slot wall or the second slot wall; and

[0079] a portion between the first edge and the second edge and having a cross-section,

[0080] wherein the cross-section of at least two of the two or more coils are different.

[0081] Example 2. The stator of Example 1, wherein the cross-sections being different comprises the shapes of the cross-sections being different.

[0082] Example 3. The stator of any one of Examples 1-2, wherein the cross-sections have the same area.

[0083] Example 4. The stator of any one of Examples 1-3, wherein the cross-section of each of the two or more coils comprises a first dimension between the first edge and the second edge,

[0084] the stator slot comprises a non-rectangular stator slot having a slot bottom with a larger dimension than a slot opening, a coil proximate to the slot bottom having a larger first dimension than a coil proximate to the slot opening.

[0085] Example 5. The stator of any one of Examples 1-4, wherein,

[0086] the same stator slot includes a first stator winding and a second stator winding,

[0087] the first stator winding is associated with the first slot wall,

[0088] the second stator winding is associated with the second slot wall;

[0089] each of the first stator winding and the second stator winding comprises the two or more coils.

[0090] Example 6. The stator of Example 5, wherein,

[0091] the first stator winding and the second stator winding are symmetrically disposed within the same stator slot.

[0092] Example 7. The stator of any one of Examples 1-6, wherein at least one of the two or more coils comprises a multi-layer structure around the stator tooth, the multi-layer structure being integrally formed, at least a portion of the multi-layer structure having the same cross-section.

[0093] Example 8. The stator of any one of Examples 1-7, wherein two adjacent ones of the two or more coils are connected by a connection portion, the connection portion disposed outside the stator slot.

[0094] Example 9. The stator of any one of Examples 1-8, wherein each of the two or more coils includes one or more layers of a racetrack shape that fits with a corresponding stator tooth.

[0095] Example 10. The stator of Example 9, wherein the racetrack shape includes:

[0096] a long strip portion disposed at least partially in the stator slot; and

[0097] an arcuate portion disposed outside the stator slot,

[0098] wherein a connection portion for connecting two adjacent ones of the two or more coils is disposed at least one of:

[0099] the connection portion is disposed on the arcuate portion,

[0100] the connection portion is disposed on a first extension portion extending from the arcuate portion to outside the arcuate portion, or

[0101] the connection portion is disposed on a second extension portion extending from the long strip portion to outside the arcuate portion.

[0102] Example 11. The stator of Example 10, wherein the connection portion includes a bent portion of the arcuate portion, the first extension portion, or the second extension portion of one of the two adjacent coils formed by bending.

[0103] Example 12. The stator of Example 10, wherein each coil includes a first connection portion disposed on a first end face and a second connection portion disposed on a second end face, the first connection portion disposed on one of the first extension portion and the second extension portion, the second connection portion disposed on the other of the first extension portion and the second extension portion.

[0104] Example 13. The stator of any one of Examples 1-12, wherein a cooling fluid is included in a gap inside the stator slot.

[0105] Example 14. The stator of any one of Examples 1-13, wherein

[0106] The stator winding associated with the one of the first slot wall or the second slot wall comprises one stator winding, the one stator winding comprising the two or more coils connected end to end.

[0107] Example 15. The stator of any one of Examples 1-13, wherein,

[0108] The stator winding associated with the one of the first slot wall or the second slot wall comprises two or more stator windings in parallel spaced and electrically isolated from each other,

[0109] Each of the two or more stator windings comprises the two or more coils connected end to end.

[0110] Example 16. The stator of Example 15, wherein the two or more stator windings in parallel spaced and electrically isolated from each other comprise two stator windings,

[0111] The connection of the two or more coils of a third stator winding of the two stator windings is disposed outside the stator slot and at a first side,

[0112] The connection of the two or more coils of a fourth stator winding of the two stator windings is disposed outside the stator slot and at a second side opposite the first side.

[0113] Example 17. A stator, comprising:

[0114] a stator core comprising a plurality of spaced apart stator teeth, a stator slot formed between two adjacent stator teeth, the stator slot comprising a first slot wall associated with a first stator tooth of the two adjacent stator teeth and a second slot wall associated with a second stator tooth of the two adjacent stator teeth; and

[0115] a stator winding disposed around the stator teeth,

[0116] wherein the stator slot comprises a plurality of stator slots, at least one of the plurality of stator slots comprising:

[0117] a stator winding associated with the first slot wall and as recited in Example 15, and

[0118] a stator winding associated with the second slot wall and as recited in Example 16.

[0119] Example 18. The stator of Example 17, wherein the stator comprises a plurality of stator teeth, and wherein:

[0120] a first stator tooth of the plurality of stator teeth has a stator winding as described in example 15 wound thereon,

[0121] a second stator tooth of the plurality of stator teeth adjacent to the first stator tooth has a stator winding as described in example 16 wound thereon;

[0122] a third stator tooth of the plurality of stator teeth adjacent to the second stator tooth and different from the first stator tooth has a stator winding as described in example 16 wound thereon.

[0123] example 19. The stator of any one of examples 17-18, wherein the stator is for an electric motor, the stator winding associated with the second slot wall and as described in example 16 comprises a third stator winding and a fourth stator winding,

[0124] the third stator winding and the fourth stator winding are configured to be electrically connected or electrically disconnected.

[0125] example 20. A rotor, the rotor comprising:

[0126] a rotor core comprising a plurality of spaced apart rotor teeth, a rotor slot formed between two adjacent rotor teeth, the rotor slot comprising a first slot wall associated with a first rotor tooth of the two adjacent rotor teeth and a second slot wall associated with a second rotor tooth of the two adjacent rotor teeth; and

[0127] a rotor winding disposed around the rotor teeth and at least a portion of the rotor winding is disposed within the rotor slot, the rotor winding comprising two or more coils stacked, each of the two or more coils comprising within the rotor slot:

[0128] a first edge abutting one of the first slot wall or the second slot wall;

[0129] a second edge distal from the one of the first slot wall or the second slot wall; and

[0130] a portion between the first edge and the second edge and having a cross-section,

[0131] wherein the cross-sections of at least two of the two or more coils are different.

[0132] example 21. The rotor of example 20, wherein the cross-sections being different comprises the shapes of the cross-sections being different.

[0133] example 22. The rotor of any one of examples 20-21, wherein the areas of the cross-sections are the same.

[0134] Example 23. The rotor of any one of Examples 20-22, wherein the cross-section of each of the two or more coils comprises a first dimension between the first edge and the second edge,

[0135] the rotor slot comprises a non-rectangular rotor slot having a slot bottom portion with a larger dimension than a slot opening, a coil proximate to the slot bottom portion having a larger first dimension than a coil proximate to the slot opening.

[0136] Example 24. The rotor of any one of Examples 20-23, wherein,

[0137] a first rotor winding and a second rotor winding are included within the same rotor slot,

[0138] the first rotor winding is associated with the first slot wall,

[0139] the second rotor winding is associated with the second slot wall;

[0140] each of the first rotor winding and the second rotor winding comprises the two or more coils.

[0141] Example 25. The rotor of Example 24, wherein,

[0142] the first rotor winding and the second rotor winding are symmetrically disposed within the same rotor slot.

[0143] Example 26. The rotor of any one of Examples 20-25, wherein at least one coil of the two or more coils comprises a multi-layer structure around the rotor tooth, the multi-layer structure being integrally formed, at least a portion of the multi-layer structure having the same cross-section.

[0144] Example 27. The rotor of any one of Examples 20-26, wherein two adjacent coils of the two or more coils are connected by a connection portion, the connection portion being disposed outside the rotor slot.

[0145] Example 28. The rotor of any one of Examples 20-27, wherein each coil of the two or more coils comprises one or more layers of a racetrack shape that fits with a corresponding rotor tooth.

[0146] Example 29. The rotor of Example 28, wherein the racetrack shape comprises:

[0147] an elongated portion disposed at least partially in the rotor slot; and

[0148] an arcuate portion disposed outside the rotor slot,

[0149] wherein the connection portion for connecting adjacent two of the two or more coils is provided as at least one of:

[0150] the connection portion is provided on the arc-shaped portion,

[0151] the connection portion is provided on a first extension portion extending from the arc-shaped portion to outside of the arc-shaped portion, or

[0152] the connection portion is provided on a second extension portion extending from the long strip-shaped portion to outside of the arc-shaped portion.

[0153] Example 30. The rotor of example 29, wherein the connection portion comprises a bent portion of the arc-shaped portion, the first extension portion, or the second extension portion of one of the adjacent two coils formed by bending.

[0154] Example 31. The rotor of example 29, wherein each coil comprises a first connection portion provided on a first end surface and a second connection portion provided on a second end surface, the first connection portion is provided on one of the first extension portion and the second extension portion, and the second connection portion is provided on the other of the first extension portion and the second extension portion.

[0155] Example 32. The rotor of any one of examples 20-31, wherein a cooling fluid is included in the gap inside the rotor slot.

[0156] Example 33. The rotor of any one of examples 20-32, wherein

[0157] the rotor winding associated with the one of the first slot wall or the second slot wall comprises one rotor winding, the one rotor winding comprising the two or more coils connected end to end.

[0158] Example 34. The rotor of any one of examples 20-32, wherein,

[0159] the rotor winding associated with the one of the first slot wall or the second slot wall comprises two or more rotor windings in parallel spaced and electrically isolated from each other,

[0160] each of the two or more rotor windings comprises the two or more coils connected end to end.

[0161] Example 35. The rotor of example 34, wherein the two or more rotor windings in parallel spaced and electrically isolated from each other comprise two rotor windings,

[0162] a connection of the two or more coils of a third of the two rotor windings is disposed outside the rotor slot and at a first side,

[0163] a connection of the two or more coils of a fourth of the two rotor windings is disposed outside the rotor slot and at a second side opposite the first side.

[0164] Example 36. A rotor comprising:

[0165] a rotor core comprising a plurality of spaced apart rotor teeth, a rotor slot being formed between two adjacent rotor teeth, the rotor slot comprising a first slot wall associated with a first of the two adjacent rotor teeth and a second slot wall associated with a second of the two adjacent rotor teeth; and

[0166] a rotor winding disposed about the rotor teeth,

[0167] wherein the rotor slot comprises a plurality of rotor slots, at least one of the plurality of rotor slots comprising:

[0168] the rotor winding associated with the first slot wall as described in Example 33, and

[0169] the rotor winding associated with the second slot wall as described in Example 34.

[0170] Example 37. The rotor of Example 36, wherein the rotor comprises a plurality of rotor teeth, and wherein:

[0171] a first of the plurality of rotor teeth has wound thereon the rotor winding as described in Example 33,

[0172] a second of the plurality of rotor teeth adjacent to the first rotor tooth has wound thereon the rotor winding as described in Example 34;

[0173] a third of the plurality of rotor teeth adjacent to the second rotor tooth and different from the first rotor tooth has wound thereon the rotor winding as described in Example 34.

[0174] Example 38. The rotor of any one of Examples 36-37, wherein the rotor is for an electric motor, the rotor winding associated with the second slot wall as described in Example 34 comprising a third rotor winding and a fourth rotor winding,

[0175] the third rotor winding and the fourth rotor winding are configured to be electrically connected or electrically disconnected.

[0176] Example 39. An electric motor comprising a stator and a rotor, wherein

[0177] the stator comprises the stator of any one of examples 1-19; and / or

[0178] the rotor comprises the rotor of any one of examples 20-38.

[0179] Example 40. An electrically powered device comprising the electric motor of example 39.

Claims

1. A stator, the stator comprising: a stator core comprising a plurality of spaced apart stator teeth, between which two adjacent stator teeth a stator slot is formed, the stator slot comprising a first slot wall associated with a first stator tooth of the two adjacent stator teeth, and a second slot wall associated with a second stator tooth of the two adjacent stator teeth; and a stator winding arranged around the stator teeth, and at least a portion of the stator winding is arranged within the stator slot, the stator winding comprising two or more stacked coils, each of the two or more coils comprising within the stator slot: a first edge against one of the first slot wall or the second slot wall; a second edge away from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross section, wherein the cross section of at least two of the two or more coils are different. the cross sections are different in shape.

2. The stator of claim 1, wherein, the cross sections are the same in area.

3. The stator of claim 2, wherein, the cross section of each of the two or more coils comprises a first dimension between the first edge and the second edge, 4. The stator of claim 1, wherein, the stator slot comprises a non-rectangular stator slot having a slot bottom portion with a dimension larger than a slot opening portion, a coil closer to the slot bottom portion having a larger first dimension than a coil closer to the slot opening portion.

5. The stator of claim 1, wherein, the same stator slot comprises a first stator winding and a second stator winding, the first stator winding is associated with the first slot wall, the second stator winding is associated with the second slot wall; each of the first stator winding and the second stator winding comprises the two or more coils.

6. The stator of claim 5, wherein, the first stator winding and the second stator winding are symmetrically arranged within the same stator slot. at least one of the two or more coils comprises a multi-layer structure around the stator tooth, the multi-layer structure is integrally formed, at least a portion of the multi-layer structure has the same cross section.

7. The stator of claim 1, wherein, adjacent two of the two or more coils are connected by a connection portion, the connection portion is arranged outside the stator slot.

8. The stator of claim 1, wherein, each of the two or more coils comprises one or more track shapes adapted to the corresponding stator tooth.

9. The stator of claim 1, wherein, the track shape comprises:

10. The stator of claim 9, wherein, an elongated portion arranged at least partially within the stator slot; and an arcuate portion arranged outside the stator slot, wherein the connection portion for connecting adjacent two of the two or more coils is arranged at least one of: the connection portion is arranged on the arcuate portion, the connection portion is arranged on a first extension portion extending from the arcuate portion to outside the arcuate portion, or the connection portion is arranged on a second extension portion extending from the elongated portion to outside the arcuate portion. ​ 11. The stator of claim 10, wherein, The connection comprises a bent portion of the arcuate portion, the first extension portion, or the second extension portion of one of the two adjacent coils formed by bending.

12. The stator of claim 10, wherein, Each coil comprises a first connection disposed on a first end face and a second connection disposed on a second end face, the first connection disposed on one of the first extension portion and the second extension portion, the second connection disposed on the other of the first extension portion and the second extension portion.

13. The stator of claim 1, wherein, The gap inside the stator slot comprises a cooling fluid.

14. The stator of any one of claims 1-13, wherein The stator winding associated with the one of the first slot wall or the second slot wall comprises one stator winding, the one stator winding comprising the two or more coils connected end to end.

15. The stator of any one of claims 1-13, wherein, The stator winding associated with the one of the first slot wall or the second slot wall comprises two or more stator windings in parallel spaced and electrically isolated from each other, Each of the two or more stator windings comprises the two or more coils connected end to end.

16. The stator of claim 15, wherein, The two or more stator windings in parallel spaced and electrically isolated from each other comprise two stator windings, The connection of the two or more coils of a third stator winding of the two stator windings is disposed outside the stator slot and at a first side, The connection of the two or more coils of a fourth stator winding of the two stator windings is disposed outside the stator slot and at a second side opposite the first side.

17. A stator, the stator comprising: a stator core comprising a plurality of spaced apart stator teeth, a stator slot formed between two adjacent stator teeth, the stator slot comprising a first slot wall associated with a first stator tooth of the two adjacent stator teeth, and a second slot wall associated with a second stator tooth of the two adjacent stator teeth; and a stator winding disposed around the stator teeth, wherein the stator slot comprises a plurality of stator slots, at least one of the plurality of stator slots comprising: a stator winding associated with the first slot wall and as claimed in claim 15, and a stator winding associated with the second slot wall and as claimed in claim 16.

18. The stator of claim 17, wherein, The stator comprises a plurality of stator teeth, and wherein: a first stator tooth of the plurality of stator teeth is wound with a stator winding as claimed in claim 15, a second stator tooth of the plurality of stator teeth adjacent to the first stator tooth is wound with a stator winding as claimed in claim 16; a third stator tooth of the plurality of stator teeth adjacent to the second stator tooth and different from the first stator tooth is wound with a stator winding as claimed in claim 16.

19. The stator of claim 17, wherein, The stator is for an electric motor, the stator winding associated with the second slot wall and as claimed in claim 16 comprises a third stator winding and a fourth stator winding, wherein the third stator winding and the fourth stator winding are configured to be electrically connected or electrically disconnected.

20. A rotor comprising: a rotor core comprising a plurality of spaced apart rotor teeth, a rotor slot formed between two adjacent rotor teeth the rotor slot comprising a first slot wall associated with a first one of the two adjacent rotor teeth, and a second slot wall associated with a second one of the two adjacent rotor teeth; and a rotor winding disposed around the rotor teeth and at least a portion of the rotor winding is disposed within the rotor slot, the rotor winding comprising two or more stacked coils, each of the two or more coils comprising within the rotor slot: a first edge against one of the first slot wall or the second slot wall; a second edge away from the one of the first slot wall or the second slot wall; and a portion between the first edge and the second edge and having a cross-section, wherein the cross-section is different for at least two of the two or more coils.

21. An electric motor comprising a stator and a rotor, wherein the stator comprises the stator of any one of claims 1-19; and / or the rotor comprises the rotor of claim 20.

22. An electrically powered device comprising the electric motor of claim 21. ​

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