Axial Flux Motor with Distributed Windings

Abstract

The present invention relates to an axial flux motor with distributed windings. An axial flux motor with reduced spatial harmonics is provided, which includes a rotor having a plurality of magnets. A rotor shaft is coupled to the rotor. A stator faces the rotor, and an air gap is defined between the rotor and the stator. The stator includes a plurality of electromagnetic components defining a plurality of magnetic poles. The electromagnetic components include a plurality of columns, a plurality of slots, and a plurality of distributed conductive windings, and the plurality of distributed conductive windings are disposed in non-adjacent slots of the plurality of slots and span these slots. At least one conductive winding has a winding pitch span greater than or equal to about 3 and less than or equal to about 20. The axial flux motor may include two rotors and one stator, or two stators and one rotor. Such an axial flux motor has a short pitch, providing the required reduced spatial harmonics to improve motor performance.

Description

[0001] Introduction

[0002] This section provides background information related to the present disclosure, which is not necessarily prior art. Technical Field

[0003] The present disclosure generally relates to axial flux motors having a stator design for reducing spatial harmonics to improve performance. Background Art

[0004] An electric motor converts electrical energy into mechanical work by generating torque. Electric vehicles, including hybrid vehicles, employ electric motors such as induction motors and permanent magnet motors to drive the vehicle and capture braking energy when used as a generator. Generally, an electric motor includes a rotor that rotates during operation and a stationary stator. The rotor may include a plurality of permanent magnets and rotates relative to the fixed stator. The rotor is connected to a rotor shaft that also rotates with the rotor. The rotor including the permanent magnets is separated from the stator by a predetermined air gap. The stator includes conductors in the form of wire windings. When electrical energy is applied through the wire windings, a magnetic field is generated. When electrical energy or power is fed into the conductive windings of the stator, the power can be transferred across the air gap by magnetic flux, generating a torque acting on the permanent magnets in the rotor. In this way, mechanical power can be transferred to or extracted from the rotating rotor shaft. In an electric vehicle, the rotor thus transfers torque to the drive wheels of the vehicle via a gear set and a rotating shaft.

[0005] Two common types of electric motors include radial flux type or axial flux type motors. In a radial flux motor, the rotor and stator are typically in a concentric or nested configuration, so when the stator is energized, it generates magnetic flux that extends radially from the stator to the rotor. Thus, the conductive windings in the stator are typically arranged perpendicular to the axis of rotation, thereby generating a magnetic field that is oriented in the radial direction from the axis of rotation (along the rotor shaft). In an axial flux motor, a magnetic field parallel to the axis of rotation is generated by the wire windings in the stator, so the magnetic flux extends parallel to the axis of rotation (parallel to the rotor shaft). In certain applications, axial flux motors are desirable because they are relatively light, produce increased power, and have a compact size compared to radial flux motors. Summary of the Invention

[0006] This section provides an overview of the present disclosure, not an exhaustive disclosure of its full scope or all of its features.

[0007] The present disclosure relates to an axial flux motor with reduced spatial harmonics. In certain variations, the axial flux motor includes a rotor and a rotor shaft coupled to the rotor, the rotor including a plurality of magnets. The rotor shaft defines a rotational axis about which the rotor is configured to rotate. A stator faces the rotor and defines an air gap therebetween. The stator is stationary and includes a plurality of electromagnetic components defining a plurality of magnetic poles. The plurality of electromagnetic components includes a plurality of posts, a plurality of slots, and a plurality of distributed conductive windings disposed in non-adjacent slots of the plurality of slots and spanning across the slots. At least one of the plurality of distributed conductive windings has a winding pitch span greater than or equal to about 3 to less than or equal to about 20.

[0008] In one aspect, each of the plurality of distributed conductive windings has a winding pitch span greater than or equal to about 3 to less than or equal to about 10.

[0009] In one aspect, the winding pitch span is 5.

[0010] In one aspect, a corresponding slot of the plurality of slots has a maximum number of 10 conductive windings.

[0011] In one aspect, the slot stager is greater than or equal to about 1 and less than or equal to about 8.

[0012] In one aspect, the plurality of magnetic poles is greater than or equal to 2 to less than or equal to about 30.

[0013] In one aspect, spatial harmonics of orders less than or equal to the fundamental harmonic frequency are eliminated in the axial flux motor, and spatial harmonics of orders greater than or equal to the fundamental harmonic frequency are reduced by greater than or equal to about 50%.

[0014] In one aspect, the plurality of slots is greater than or equal to about 12 to less than or equal to about 96.

[0015] In one aspect, the plurality of magnetic poles is 8, the pitch of the plurality of magnetic poles is about 6 degrees, the plurality of slots is 48, each slot has two layers of conductive windings, the number of conductive windings per slot is 2, and the slot stager is 1.

[0016] In one aspect, the axial flux motor is a three-phase motor and includes a three-phase distributed conductive winding.

[0017] In one aspect, the stator includes an insulated metal strip that is wound to form an annular shape that defines the plurality of posts and the plurality of slots.

[0018] The present disclosure also relates to an axial flux motor with reduced spatial harmonics, which includes two disk-shaped rotors, each rotor including a plurality of magnets. In addition, the axial flux motor includes a rotor shaft coupled to the two disk-shaped rotors. The rotor shaft defines a rotation axis, and the disk-shaped rotors are configured to rotate about the rotation axis. A disk-shaped stator is disposed between the two disk-shaped rotors. The disk-shaped stator is stationary and includes a plurality of electromagnetic components defining a plurality of magnetic poles. The plurality of electromagnetic components includes a plurality of columns, a plurality of slots greater than or equal to about 12 and less than or equal to about 96, and a plurality of distributed conductive windings, the plurality of distributed conductive windings being disposed in non-adjacent slots of the plurality of slots and spanning these slots. At least one conductive winding has a winding pitch span greater than or equal to about 3 and less than or equal to about 20. The axial flux motor also has a first air gap defined between a first one of the disk-shaped rotors and the disk-shaped stator. A second air gap is defined between a second one of the disk-shaped rotors and the disk-shaped stator.

[0019] In one aspect, the plurality of electromagnetic components includes a first plurality of electromagnetic components and a second plurality of electromagnetic components. The disk-shaped stator includes a first side having the first plurality of electromagnetic components, the first side facing a first rotor of the two disk-shaped rotors and defining the first air gap. The disk-shaped stator includes a second side having the second plurality of electromagnetic components, the second side facing a second rotor of the two disk-shaped rotors and defining the second air gap.

[0020] In one aspect, the disk-shaped stator includes a first side that faces a first rotor of the two disk-shaped rotors and defines the first air gap and the disk-shaped stator. A second side of the disk-shaped stator faces a second rotor of the two disk-shaped rotors and defines the second air gap.

[0021] In one aspect, spatial harmonics of order less than or equal to 7 are eliminated in the axial flux motor, and spatial harmonics of order greater than or equal to 7 are reduced by greater than or equal to about 50%.

[0022] In one aspect, the number of magnetic poles is 8, the pitch of the plurality of magnetic poles is about 6 degrees, the number of slots is 48, each slot has two layers of conductive windings, the number of conductive windings per slot is 2, and the slot stagger amount is 1.

[0023] The present disclosure also relates to an axial flux motor with reduced spatial harmonics. The axial flux motor has two stationary disk-shaped stators. Each of the two disk-shaped stators includes a plurality of electromagnetic components defining a plurality of magnetic poles. The plurality of electromagnetic components includes a plurality of columns, a plurality of slots greater than or equal to about 12 and less than or equal to about 96, and a plurality of distributed conductive windings disposed in non-adjacent slots of the plurality of slots and spanning these slots. At least one of the plurality of distributed conductive windings has a winding pitch span greater than or equal to about 3 and less than or equal to about 20. The axial flux motor also has a rotor disposed between the two disk-shaped stators and including a plurality of magnets. A rotor shaft is coupled to the rotor and defines a rotational axis, and the rotor is configured to rotate about the rotational axis. A first air gap is defined between the first of the disk-shaped stators and the rotor. A second air gap is defined between the second of the disk-shaped stators and the rotor.

[0024] In one aspect, spatial harmonics of order less than or equal to 7 are eliminated in the axial flux motor, and spatial harmonics of order greater than or equal to 7 are reduced by greater than or equal to about 50%.

[0025] In one aspect, the number of magnetic poles is 8, the pitch of the plurality of magnetic poles is about 6 degrees, the number of slots is 48, each slot has two layers of conductive windings, the number of conductive windings per slot is 2, and the slot stagger amount is 1.

[0026] From the description provided herein, additional application areas will become apparent. The description and specific examples in this summary are for illustrative purposes only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0028] Figure 1A –1B shows a simplified schematic diagram of the conductive windings of the stator of an electric motor. Figure 1A Shows a design with a plurality of concentrated conductive windings for a three-phase motor. Figure 1B Shows a design with a distributed configuration of a plurality of distributed conductive windings for a three-phase motor.

[0029] Figure 2 Shows an exploded view of an axial flux motor assembly having one stator and two rotors.

[0030] Figure 3 Shows the spatial harmonics of the concentrated winding design of the motor.

[0031] Figure 4 Shows the spatial harmonics of the distributed winding design of the motor.

[0032] Figure 5 Shows an example of a section of a stator with a distributed winding and short pitch design for an axial flux motor prepared according to certain aspects of the present disclosure.

[0033] Figure 6 Shows a metal strip having features formed by a lamination manufacturing process that forms a stator core for an axial flux motor according to certain aspects of the present disclosure.

[0034] Figure 7 Shows a side view of a stator core formed from the Figure 6 metal strip in

[0035] Figure 8 Shows an axial flux motor prepared according to certain aspects of the present disclosure, the motor having a stator with a distributed winding and two rotors.

[0036] Figure 9 Shows another variant of an axial flux motor prepared according to certain aspects of the present disclosure, the motor having a stator and two rotors, the stator having two different sides with distributed windings.

[0037] Figure 10 Shows another variant of an axial flux motor prepared according to certain aspects of the present disclosure, the motor having a centrally disposed rotor with two stators, each stator having a distributed winding.

[0038] In several views of the drawings, corresponding reference numerals denote corresponding components. Detailed Description

[0039] Exemplary embodiments are provided so that the present disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details are set forth, such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, and that the exemplary embodiments may be embodied in many different forms and neither should be construed as limiting the scope of the present disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known techniques have not been described in detail.

[0040] The terms used herein are for the purpose of describing particular example embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may also be intended to include the plural forms, unless the context clearly indicates otherwise. The terms "comprising", "including", "containing" and "having" are inclusive and thus specify the presence of the stated features, elements, compositions, steps, integers, operations and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. Although the open-ended term "comprising" is to be understood as a non-limiting term used to describe and claim the various embodiments set forth herein, in some instances, the term may alternatively be understood to be a more limiting and restrictive term, such as "consisting of" or "consisting essentially of". Thus, for any given embodiment listing compositions, materials, components, elements, features, integers, operations and / or process steps, the present disclosure also specifically includes embodiments consisting of or consisting essentially of these listed compositions, materials, components, elements, features, integers, operations and / or process steps. In the case of "consisting of", alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations and / or process steps, while in the case of "consisting essentially of", any additional compositions, materials, components, elements, features, integers, operations and / or process steps that materially affect the basic and novel features are excluded from that embodiment, but any compositions, materials, components, elements, features, integers, operations and / or process steps that do not materially affect the basic and novel features may be included in that embodiment.

[0041] Any method steps, processes and operations described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically identified as an order of performance. It should also be understood that, unless otherwise stated, additional or alternative steps may be employed.

[0042] When a component, element or layer is referred to as being "on", "engaged to", "connected to" or "coupled to" another element or layer, it can be directly on, engaged, connected or coupled to another component, element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on", "directly engaged to", "directly connected to" or "directly coupled to" another element or layer, intervening elements or layers may not be present. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms may be used only to distinguish one step, element, component, region, layer, or section from another step, element, component, region, layer, or section. Terms such as "first", "second", and other numerical terms do not imply an order or sequence when used herein unless the context clearly dictates otherwise. Thus, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0044] For ease of description, spatially or temporally relative terms such as "before", "after", "inside", "outside", "below", "beneath", "lower", "above", "upper", etc. may be used herein to describe the relationship of one element or feature to another element or feature, as shown in the figures. Spatially or temporally relative terms may be intended to include different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.

[0045] Throughout this disclosure, numerical values represent approximate measures or limitations of ranges, to include minor deviations from a given value and embodiments having approximately the recited value as well as those having the recited exact value. Except for the working examples provided at the end of the detailed description, numerical values (e.g., numerical values of quantities or conditions) of all parameters in this specification (including the appended claims) should be understood to be modified in all instances by the term "about", whether or not "about" actually appears before the numerical value. "About" means that the recited numerical value allows some slight imprecision (some exact close in value; approximately or reasonably close to the value; nearly). If the imprecision provided by "about" is not understood in the art to have this ordinary meaning, then "about" as used herein at least represents variations that may be caused by ordinary methods of measuring and using such parameters. For example, "about" may include variations of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some aspects optionally less than or equal to 0.1%.

[0046] In addition, the disclosure of a range includes the disclosure of all values within the entire range and further divided ranges, including the endpoints and sub-ranges given for the range.

[0047] Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0048] In various aspects, the present disclosure relates to an axial flux motor having reduced spatial harmonics and thus improved performance. In most axial flux motors, for a smaller package, the conductive windings in the stator can be of a concentrated construction. An example of a concentrated conductive winding design 30 is shown in Figure 1A as follows. Figure 2 FIG. Figure 2 shows a simplified view of an axial flux motor assembly 10 that includes a disk-shaped first rotor 12 and a disk-shaped second rotor 14 configured to rotate. Since the first rotor 12 and the second rotor 14 have the same design, their common components will be described here. Each rotor has a backplate 16 and a plurality of permanent magnets 18. A disk-shaped stator 20 is disposed between the first rotor 12 and the second rotor 14. The stator 20 is fixed and stationary, while the first rotor 12 and the second rotor 14 rotate during operation. The stator includes a plurality of electromagnetic components 22 that are separated from each other to form electromagnetic poles.

[0049] Referring again to Figure 1A , the electromagnetic components of the stator have a plurality of stator teeth or posts 32. A plurality of slots 34 are defined between the respective stator posts 32. A first conductive winding 40 of a first phase designated as "A" is disposed (e.g., wound at least once) around a first post 35 and within two adjacent slots 34 defined by the first post 32. Similarly, a second conductive winding 42 of a second phase designated as "B" is disposed around another second post 36 and within two adjacent slots 34 of the second post 36. Finally, a third conductive winding 44 of a third phase designated as "C" is disposed around a third post 38 that is disposed between the first post 35 and the second post 36. The third conductive winding 44 occupies the slot adjacent to the third post 38, which also contains the first conductive winding 40 or the second conductive winding 42. Figure 1A The configuration shown is a 2-pole concentrated winding design with 0.5 slots / pole / phase. Thus, the first conductive winding 40, the second conductive winding 42, and the third conductive winding 44 together define two magnetic poles 46, 48 having opposite polarities (N, S). Although many axial flux motors are formed of concentrated windings, they suffer from more harmonics in the spatial flux distribution in the air gap, which introduces losses in the magnets and the stator core (e.g., iron core).

[0050] In accordance with various aspects of the present disclosure, a stator having a distributed winding configuration is provided that reduces spatial harmonics, which in turn greatly reduces any losses in the magnets and the stator core. Generally, a distributed conductive winding can be considered to have windings disposed in non-adjacent slots and spanning those slots. By way of example, a distributed winding design 50 is shown in Figure 1Bshown in. The stator has a plurality of stator teeth or posts 52. A plurality of slots 54 are defined between the respective stator posts 52. In some aspects, the plurality of slots 54 in the axial flux motor prepared according to the present disclosure may have greater than or equal to about 12 to less than or equal to about 96 slots, such as multiples of 12 (e.g., 12, 24, 36, 48, 60, 72, 84, 96). A first conductive winding 60 having a first phase designated as "A" is disposed in a first slot 70 and terminates in a non-adjacent second slot 71, and thus is disposed around three posts 52 (with slots having a pitch (designated as "P") of 3). A second conductive winding 62 having a second phase designated as "B" is disposed in a third slot 73 and a non-adjacent fourth slot 74, and thus is disposed around three posts 52 with a pitch of 3. A third conductive winding 64 having a third phase designated as "C" is disposed in a fifth slot 75 and a non-adjacent sixth slot 76, and thus is disposed around three posts 52 with a pitch of 3. As will be described in more detail below, in certain variations according to the present disclosure, at least one conductive winding spans from a first slot of the stator to a non-adjacent second slot to define a winding pitch span (P), which is optionally greater than or equal to about 3 to less than or equal to about 20, optionally greater than or equal to about 3 to less than or equal to about 10, optionally greater than or equal to about 3 to less than or equal to about 7, and in certain variations, the winding pitch span is about 5. Figure 1B The configuration shown is a 2-pole concentrated winding design with 1 slot / pole / phase. Thus, the first conductive winding 60, the second conductive winding 62, and the third conductive winding 64 together define two magnetic poles 77, 78 having opposite polarities (N, S). By combining a distributed winding with a short pitch design, the sub-harmonics in the axial flux motor can be reduced or eliminated.

[0051] Figure 3 and Figure 4 also shows the space harmonics of the concentrated winding design (as Figure 3 shown) and the distributed winding design (as Figure 4 shown). In Figure 3 , the y-axis 80 shows the winding function harmonic components (number of turns), while the x-axis 82 represents the number of cycles / 2π mechanical radians. Thus, Figure 3 shows the synchronous frequency components of a 2 / 7 slot / pole / phase concentrated winding. The numbers at the top of the bar (showing the synchronous frequency components) represent the order of the space harmonics of the corresponding winding function. It can be seen that there are many space harmonics both at the low harmonics (designated as 84) and the high harmonics (designated as 86). In the example shown, the synchronous frequency of the motor is 7. Thus, in Figure 3Among them, the fundamental harmonic frequency is 7, the third harmonic frequency is 21, the fifth harmonic frequency is 35, the seventh harmonic frequency is 49, and so on. Generally, the lower-order spatial harmonics are understood to be those with frequencies less than the first synchronous frequency (7), while the higher-order spatial harmonics have frequencies greater than the first synchronous frequency (7). Figure 4 Shows a concentrated winding, in which in addition to the spatial harmonics of the fundamental (7), third (21), fifth (35) and seventh (49) synchronous frequencies, there are many harmonics below and above the first synchronous frequency. Therefore, the presence of unwanted spatial harmonics will cause losses in the stator core and surface-mounted magnets (such as in the rotor), which results in a reduction in the performance of the axial flux motor. Although it is desirable to eliminate all spatial harmonics except the first synchronous frequency, this may actually be impossible. However, in some aspects, the axial flux motor provided by some aspects of the present disclosure has reduced lower-order harmonics 84, which have a greater amplitude than the higher-order spatial harmonics 86.

[0052] Figure 4 Shows an example of the synchronous frequency components of a 1-slot / pole / phase distributed winding for a motor. The y-axis 90 shows the winding function harmonic components (number of turns), while the x-axis 92 represents the number of cycles / 2π mechanical radians. Similarly, the numbers at the top of the selection bar (showing the synchronous frequency components) represent the order of the spatial harmonics of the corresponding winding function. Therefore, the fundamental spatial harmonic of a motor with a synchronous frequency of 7 has a third spatial harmonic of 21, a fifth spatial harmonic of 35, and a seventh spatial harmonic of 49. It can be seen that in the distributed winding, many spatial harmonics at the lower-order harmonics (designated as 94) and higher-order harmonics (designated as 96) are minimized or eliminated. In Figure 4 the distributed winding, it can be seen that, compared with the concentrated winding in Figure 3 , the lower-order spatial harmonics below the fundamental at 7 are eliminated. Similarly, when comparing Figure 3 and Figure 4 , for example, between 21 and 35 and between 35 and 49, many higher-order spatial harmonics 96 are eliminated.

[0053] In some variations, the present disclosure provides an axial flux motor in which any low-order spatial harmonics below the fundamental synchronous frequency are reduced or eliminated. In some other variations, the present disclosure provides an axial flux motor in which any high-order spatial harmonics greater than the order of the fundamental spatial harmonic of the synchronous frequency are reduced. For example, in one variation where the synchronous frequency of the axial flux motor is 7, for example, an axial flux motor with reduced spatial harmonics may not have synchronous frequency components of the fundamental spatial harmonics between 1 and 6, and may not have higher-order synchronous frequency components at, for example, 8 - 19, 22 - 34, and 36 - 48. It should be noted that if the windings are in a three-phase A, B, and C configuration, the third synchronous frequency at 21 will generally not be present. In some aspects, spatial harmonics of order less than or equal to approximately 7 are eliminated in the axial flux motor. In other aspects, spatial harmonics of order greater than or equal to approximately 7 are reduced by greater than or equal to approximately 40% in the axial flux motor, optionally by greater than or equal to approximately 50% in the axial flux motor, optionally by greater than or equal to approximately 60% in the axial flux motor, and in some aspects, optionally by greater than or equal to approximately 70% in the axial flux motor.

[0054] In some aspects according to the present disclosure, the axial flux motor has a distributed winding and the accompanying spatial harmonics are eliminated. In additional aspects, a short pitch configuration in the distributed winding is used, for example, to further reduce or eliminate higher-order harmonics, such as Figure 4 the fifth and seventh synchronous harmonics in

[0055] Figure 5 An example of a section 180 of a stator for an axial flux motor having a distributed winding and a short pitch design prepared according to some aspects of the present disclosure is shown. The stator section 180 includes a plurality of posts 182 and a plurality of slots 184, each slot numbered from 0 to 7. As shown, each slot 184 includes a first layer 184A and a second layer 184B that respectively receive windings. Thus, this can be considered a two-layer slot configuration. In addition, the section 180 has a winding slot distribution of 2. The winding slot distribution is the span in the positive direction of each phase of the winding. For example, the positive direction of the phase A winding (A+) in the first layer 184A occupies two slot numbers, namely 0 and 1. It should be noted that the corresponding slots in the plurality of slots can have a maximum of 10 conductive windings. The stator section 180 can form a stator having 48 slots and thus 8 poles.

[0056] In Figure 5In the design shown, the slot misalignment is 1, which means that the mismatch between the slots is an offset of 1, such that every other slot will have a mismatch between the phase windings between the first layer 184A and the second layer 184B. Thus, the second slot 184 labeled "2" has A+ in the first layer 184A and C– in the second layer 184B (having an A+ / C– configuration), while the fourth slot labeled "4" has C– in the first layer 184A and B+ in the second layer 184B (having a C– / B+ configuration), and the sixth slot labeled "6" has B+ in the first layer 184A and A– in the second layer 184B (having a B+ / A– configuration). It should be noted that in the example shown, the slots labeled 1, 3, 5, and 7 share the same phase windings, i.e., A+ / A+, C– / C–, B+ / B+, A– / A– in the first layer 184A / second layer 184B.

[0057] A representative conductive winding 190 is shown. The conductive winding 190 shows the orientation of the current and flux designated by + and - for the first phase winding (designated "A"). The positive and negative sides of a single conductive winding 190 (e.g., A+) can be disposed in one slot (e.g., the slot designated 1) on one side, while the other side of the conductive winding 190 (e.g., A-) is disposed in another slot (e.g., the slot designated 6). Thus, the conductive winding 190 spans from the second layer 184B in the first slot 184 labeled "1" to the first layer 184A in the sixth slot 184 labeled "6". In this way, a winding pitch "P" (labeled 192) of the winding spanning from one slot to another is defined for the conductive winding 190 that spans 5 slots 184. Thus, for the conductive winding 190 and the other windings shown in the stator segment 180, the winding pitch span (P) is 5, although the winding pitch span can be any value discussed previously above. The windings on opposite sides of each stator post 182 can have the same or different / opposite magnetization directions.

[0058] The conductive windings can be disposed on one side of the stator poles 182 or in the slots 184, which can have a first magnetization direction (e.g., corresponding to a positive orientation). The windings on opposite sides of the stator poles 182 in adjacent slots can have opposite magnetization directions (e.g., corresponding to a negative magnetization direction). Within a stator slot 184, a set of windings can have the same orientation / polarity, or can be a mixture of orientations and polarities between a first layer 184A and a second layer 184B. Thus, as described above, every other slot can have a mismatch between the phase windings between the first layer 184A and the second layer 184B, such that the windings on one side of the stator poles 182 can be both a first magnetization direction (e.g., corresponding to a positive orientation) and a second magnetization direction (e.g., corresponding to a negative orientation), while on the other side of the stator poles 182, the windings can have a single orientation, either the first magnetization direction or the second magnetization direction. In this way, a short-pitch distributed winding design can solve the high harmonic problem and minimize the high harmonics. It should be noted that the windings in the axial flux stator can have other configurations, and these are non-limiting representative examples.

[0059] For example, the reduction of space harmonics by using a short-pitch distributed winding can be understood by the following equation:

[0060]

[0061] where y is the pitch (P) of a winding, τ is the pitch of a pole of the magnet, and υ is the reduced space harmonic. For the exemplary embodiment described in the context of Figure 5 , y is 5 and τ is 6, so υ is 6. In this way, the amplitudes of the fifth (5 th ) and seventh (7 th ) space harmonics (close to 6) are greatly reduced. Thus, according to certain aspects of the present disclosure, an axial flux motor design is envisioned that includes distributed windings to reduce or eliminate sub-harmonics, and a short pole pitch that reduces or minimizes high harmonics through a short winding pitch span. In this way, the losses in the magnet and ferromagnetic core components can be significantly reduced to improve the performance of the axial flux motor.

[0062] In certain aspects, the stator core 200 can be formed by a lamination manufacturing process, where the laminated steel coils have features defined therein suitable for use as stator poles, including teeth and / or shoes. The stator core 200 can be formed by different manufacturing processes. In one variant, the method can include cutting or stamping the slots before winding according to a predetermined position, and then winding the laminations to form the component. In another variant, the slots can be cut one by one just before winding, so that cutting and winding can be performed simultaneously on an automated machine. As Figure 6As shown, an example of a metal strip 210 formed by such a process is shown. The metal strip 210 may be formed of a ferromagnetic material, which may be coated with, for example, an insulating material. Suitable ferromagnetic materials for stator core components are known in the art and include, by way of non-limiting example, magnetic steel. When the metal strip 210 is a laminated metal strip comprising multiple layers, the insulating material is interleaved (as a coating or different layers) between the respective layers of the multiple layers. The insulating material may be a non-magnetic material. By way of non-limiting example, the insulating coating or material may include a siloxane-based material such as silicone varnish, or a metal-organic or inorganic insulating material, such as a silicate layer, an oxide layer, a phosphate layer, and their equivalents and combinations.

[0063] The metal strip 210 may have one or more features formed therein. These features may be formed by cutting, etching, swaging, or stamping before winding or coiling. For example, the metal strip 210 may be swaged or stamped to form a predetermined and substantially uniform shape at a predetermined location along the strip 210. For example, a plurality of stator posts 212 may be formed along the metal strip 210. Each stator post 212 optionally defines a stator tooth 214 and a stator shoe 216 at its ends. Between each stator post 212, a void region may define a slot 218. When the metal strip 210 is coiled and circumferentially joined to form the stator core 200, the stator core 200 will define a plurality of stator posts 212 and slots 218 and have an annular or disc-shaped configuration. It is noted that although not shown, the metal strip 210 may be wound multiple times to form multiple concentric layers in the stator core 200. Although not shown in Figure 6 or 7, in various aspects, a plurality of conductive windings may then be disposed in the respective slots 218 in a distributed configuration such that the conductive windings are disposed in non-adjacent slots, as described above. In this way, a plurality of electromagnetic elements 220 are formed, which may be separated by channels 222 respectively to form the stator core 200. As will be understood by those skilled in the art, the coiled metal strip 210 may be contained within a housing, and the stator core 200 may include various other stator elements.

[0064] In Figure 8 is shown a non-limiting example of an electrical device in the form of an axial flux motor 100, also known as a pancake motor. The motor 100 has a first rotor 110 and a second rotor 120, both of which are connected to a rotor shaft 130 and are configured to rotate about the rotor shaft 130. The first rotor 110 and the second rotor 120 both have an annular or disc-shaped configuration with a centrally disposed hole 118. The rotor shaft 130 passes through the centrally disposed hole 118. The rotor shaft defines a rotational axis 132 about which the rotor rotates.

[0065] The stator 140 is disposed between the first rotor 110 and the second rotor 120. The stator 140 may have an annular or disc shape. The stator 140 is fixed and stationary, while the first rotor 110 and the second rotor 120 rotate on the rotor shaft 130 during operation. The first rotor 110 faces the first side 142 of the stator 140 and defines a first air gap 144 therebetween. The second rotor 120 faces the second side 146 of the stator 140 and defines a second air gap 148 therebetween.

[0066] Although the motor 100 is shown as having a central single stator 140 and two outer rotors 110, 120, other configurations are also conceivable, as will be understood by those skilled in the art and further discussed herein, including configurations having two stators and a single rotor or in which the electric motor assembly may include more or fewer rotors and / or stators, and the description herein also applies to these other embodiments. Additionally, although not currently shown, those skilled in the art will understand that, in various aspects, the electric motor assembly may further include a housing, and the rotors, stators, and shaft may be disposed within the housing. The housing may be fixed to the vehicle frame, and the shaft may be coupled to a gearbox within the vehicle, such as a reduction gearbox.

[0067] Each of the first rotor 110 and the second rotor 120 may have the same design (facing opposite directions of the stator 140), and thus common components will be described here. Each of the first rotor 110 and the second rotor 120 includes a plurality of permanent magnets 112 attached to the rotor body 114. The permanent magnets 112 may have alternating polarities. Each permanent magnet 112 defines a channel 116 therebetween, and the channel 116 may extend radially along the surface of the corresponding rotor. In this way, the permanent magnets 112 and the channels 116 may together define a plurality of magnetic poles. It should be noted that, as will be understood by those skilled in the art, the number, shape, position, and orientation of the permanent magnets 112 may differ from those shown.

[0068] The stator 140 includes a plurality of stator segments or core components 150 around which a plurality of conductive windings 152 are wound in a distributed configuration. The stator 140 defines a plurality of slots 156 between the respective stator core components 150, where the conductive windings 152 may extend over or bridge the slots 156. The stator core components 150 may include ferromagnetic cores, such as a plurality of laminated core components formed of multiple layers of ferromagnetic material (e.g., magnetic steel). Such ferromagnetic material layers are typically isolated from each other by interposed insulating materials. Alternatively, the stator core components 150 may be formed of a soft-molded composite material that includes a plurality of magnetic particles having insulating coatings and optionally distributed in a polymeric resin, such as a non-magnetic resin. As described above, in a distributed winding configuration, each conductive winding 152 may span from one slot (e.g., the first slot 160) to another non-adjacent slot (e.g., the second slot 162). The stator 140 may be fixed and stationary. Although not shown, other winding configurations and techniques understood in the art may also be contemplated, so long as a distributed winding design is employed. The conductive wires or windings 152 may include copper or a copper alloy, which may generate a magnetic field when an electric current is applied. By way of example, the conductive winding 152 may be a wire having a circular cross-section or a rectangular cross-section. In other aspects, the conductive winding 152 may be a pre-formed conductive hairpin winding that may be electrically connected and attached to corresponding terminals within the stator slots.

[0069] The rotor shaft 130 may pass through a hole 154 centrally disposed in the stator 140 and be supported by bearings (not shown), aligning the rotors 110, 120 relative to the stator 140 while allowing the rotor shaft 130 to rotate. The plurality of conductive windings 152 of the stator 140 may be formed of copper or other wires configured to generate a magnetic field when an electric current is applied, thereby interacting with the magnetic fields of a plurality of permanent magnets 112 having alternating magnetic poles located on the first rotor 110 and the second rotor 120. Different regions of the stator 140 may be selectively energized to apply a rotational force on the first rotor 110 and the second rotor 120, causing the rotors 110, 120 and the rotor shaft 130 to rotate relative to the axis of rotation 132. The axial flux motor 100 having a single stator 140 and the first rotor 110 and the second rotor 120 can be used for high-torque applications, including for electric or hybrid vehicles. In such a variant, as described above, the housing surrounding the motor 100 may be attached to the vehicle frame, and at least one output from one end of the rotor shaft 130 is coupled to a reduction gearbox or directly to the vehicle drive wheels. The vehicle application of the axial flux motor 100 is provided as an exemplary embodiment and is not intended to be limiting.

[0070] In Figure 8In the illustrated variant, each conductive winding 152 spans from a first side 142 of the stator to a second side 146. Thus, the plurality of conductive windings 152 interact with the first rotor 110 across the first air gap 144 and with the second rotor 120 across the second air gap 148.

[0071] In Figure 9 Another variant of a non - limiting example of an electrical device in the form of an axial - flux motor 300 is shown. The motor 300 has a first rotor 310 and a second rotor 320, both of which are connected to a rotor shaft 330 and are configured to rotate about the rotor shaft 330. The first rotor 310 and the second rotor 320 both have an annular or disk - shaped form with a centrally - disposed hole 318. To the extent that the components described in the context of Figure 8 are the same as those described here in the context of the axial - flux motor 300, for the sake of brevity, they are not necessarily introduced or described again here, but are to be understood as existing and having the same characteristics or functions as those described above in the context of the Figure 8 axial - flux motor 100.

[0072] The stator 340 is centrally disposed between the first rotor 310 and the second rotor 320. The stator 340 may have an annular or disk - shaped form. The first rotor 310 faces a first side 342 of the stator 340 and defines a first air gap 344 therebetween. The second rotor 320 faces a second side 346 of the stator 340 and defines a second air gap 348 therebetween.

[0073] Each of the first rotor 310 and the second rotor 320 may have the same design (facing opposite directions with respect to the stator 340), and thus common components will be described here. Each of the first rotor 310 and the second rotor 320 includes a plurality of permanent magnets 312 attached to a rotor body 314. The permanent magnets 312 may have alternating polarities. Each permanent magnet 312 defines a channel 316 such that the permanent magnets 312 and the channels 316 together may define a plurality of magnetic poles. It is noted that the number, shape, and position of the permanent magnets may be different from those shown in Figure 9 the figure.

[0074] The stator 340 includes a plurality of stator segments or core components. As shown, the first side 342 of the stator 340 has a first plurality of core components 350. The second side 346 of the stator 340 has a second plurality of core components 352. The first side 342 of the stator 340 is physically separated from the second side 346. The material forming the stator body 343 that separates the first side 342 from the second side 346 may be the same as in the foregoing embodiments, which may be an insulating laminated steel or a soft - magnetic composite material. Figure 8 and Figure 9The shape and slot openings of the stator body 343 in [reference] can be of a similar design. However, in Figure 9 In [reference], the main difference in the design is the winding configuration. The first plurality of conductive windings 354 are wound in a distributed configuration such that they are not disposed in adjacent slots. The first side 342 of the stator 340 defines a first plurality of slots 356 between the respective stator core components 350, where the conductive windings 354 can extend over or bridge the slots 356. As described above, in a distributed winding configuration, each conductive winding 354 can span from one slot (e.g., the first slot 358) to another non-adjacent slot (e.g., the second slot 360).

[0075] The second side 346 of the stator 340 defines a second plurality of slots 362 between the respective stator core components 352. The second plurality of conductive windings 364 are wound in a distributed configuration. The conductive windings 364 can extend over or bridge the second plurality of slots 362. As described above, in a distributed winding configuration, each of the second plurality of conductive windings 364 can span from one slot (e.g., the first slot 366) to another non-adjacent slot (e.g., the second slot 368).

[0076] In the stator 340, the first plurality of slots 356 and the second plurality of slots 362 on the stator 340 are separated on both sides of the stator body 343. In this way, the first plurality of conductive windings 354 and the second plurality of conductive windings 364 can be separated on both sides 342, 346, as Figure 9 shown. However, the conductive windings can also extend from one side to the other, as Figure 8 shown, which can provide greater design flexibility for the winding configuration in some aspects.

[0077] In Figure 9 In the variant shown, each of the first plurality of conductive windings 354 and the second plurality of conductive windings 364 are disposed on different first side 342 and second side 346 of the stator 340. Thus, the first plurality of conductive windings 354 interact with the first rotor 310 across the first air gap 344, while the second plurality of conductive windings 364 and the second rotor 320 interact across the second air gap 348. Although not shown, other winding configurations and techniques understood in the art can also be envisioned as described above, as long as a distributed winding design is employed.

[0078] The first plurality of conductive windings 354 and the second plurality of conductive windings 364 of the stator 340 can be formed of copper or other conductors and are configured to generate a magnetic field when a current is applied, thereby interacting with the magnetic fields of the plurality of permanent magnets 312 having alternating magnetic poles located on the first rotor 310 and the second rotor 320.

[0079] Different regions of the stator 340 can be selectively energized to apply a rotational force on the first rotor 310 and the second rotor 320, causing the rotors 310, 320 and the rotor shaft 330 to rotate relative to the rotational axis 332. The axial flux motor 300 having a single disc-shaped stator 340 and a first disc-shaped rotor 310 and a second disc-shaped rotor 320 can be used for high torque applications, including for electric or hybrid vehicles. As described above, in this variant of the axial flux motor, the windings are separated onto two different sides of the stator. The number of slots and poles can vary. In addition, different pitches can be designed for the windings. Different winding layers in a given slot can be selected. In addition, hairpin-shaped conductive windings can be employed.

[0080] In this variant, as described above, the housing surrounding the motor 300 can be attached to the vehicle frame, and at least one output from one end of the rotor shaft 330 is coupled to a reduction gearbox or directly to the vehicle drive wheels. Again, the vehicle application of the axial flux motor 300 is provided as an exemplary embodiment and is not intended to be limiting.

[0081] In Figure 10 yet another variant of a non-limiting example of an electrical device in the form of an axial flux motor 400 is shown, which has one rotor and two stators. To the extent that the components described herein in the context of the axial flux motor 400 are the same as the components Figure 9 described in Figure 8 for the sake of brevity, they are not necessarily introduced or described again herein. However, these components will be understood to be present and to have the same characteristics or functions as the above-described components in the context of, for example, the axial flux motor 100 in

[0082] The motor 400 has a first stator 410 and a second stator 420, both of which are configured to be stationary during operation. The first stator 410 has a first plurality of stator segments or core components 450A, around which a first plurality of conductive windings 452A are wound in a distributed configuration. The second stator 420 has a second plurality of stator segments or core components 450B, around which a second plurality of conductive windings 452B are wound in a distributed configuration. The first stator 410 defines a plurality of first slots 456A between the respective stator core components 450A, where the first plurality of conductive windings 452A can extend across or bridge the first slots 456A. The second stator 420 defines a plurality of second slots 456B between the respective stator core components 450B, where the first plurality of conductive windings 452A can extend across or bridge the first slots 456A. The first plurality of conductive windings 452A or the second plurality of conductive windings 452B can extend across or bridge the plurality of first slots 456A or the plurality of second slots 456B. As described above, in a distributed winding configuration, each of the conductive windings 452A, 452B in the first or second plurality can span from one slot (e.g., a first slot) to another non-adjacent slot (e.g., a second slot).

[0083] The stator core components 450A, 450B can include ferromagnetic cores, such as a plurality of laminated core components formed of a multi-layer ferromagnetic material or a soft-molded composite material, the soft-molded composite material including a plurality of magnetic particles having an insulating coating and optionally distributed in a polymer matrix, such as a non-magnetic polymer matrix. As described above, in a distributed winding configuration, each of the conductive windings 452A, 452B in the first and second plurality can span from one first slot 456A or second slot 456B to another non-adjacent first slot 456A or second slot 456B. Although not shown, other winding configurations and techniques understood in the art can also be contemplated, as long as a distributed winding design is employed.

[0084] The motor 400 has a rotor 440, which is configured to rotate about a rotor shaft 430. The rotor 440 has an annular or disc shape with a centrally disposed hole 441. The rotor 440 is centrally disposed between the first stator 410 and the second stator 420. The rotor 440 can have an annular or disc shape. The first stator 410 faces a first side 442 of the rotor 440 and defines a first air gap 444 therebetween. A second side 446 of the rotor 440 faces the second stator 420 and defines a second air gap 448 therebetween.

[0085] The rotor 440 has a plurality of permanent magnets 460 attached to the rotor body 462. The permanent magnets 460 may have alternating polarities. Each permanent magnet 460 defines a channel 464 such that the permanent magnets 460 and the channels 464 together may define a plurality of magnetic poles. It should be noted that the number, shape, and position of the permanent magnets may be different from those shown in Figure 10 as shown.

[0086] In Figure 10 the illustrated embodiment, each of the first plurality of conductive windings 452A and the second plurality of conductive windings 452B are disposed on different first side 442 and second side 446 of the rotor 440. Accordingly, the first plurality of conductive windings 452A of the first stator 410 interact with the rotor 440 across the first air gap 444, while the second plurality of conductive windings 452B of the second stator 420 interact with the rotor 440 across the second air gap 448. In this variant of the axial flux motor, two stators each having windings are disposed on two different sides of a centrally disposed rotor. The number of slots and poles may vary. Additionally, different pitches may be designed for the windings. Different winding layers may be selected within a given slot. Additionally, hairpin-shaped conductive windings may be employed.

[0087] For purposes of illustration and description, the foregoing description of the embodiments has been provided. It is not intended to be exhaustive or to limit the disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment but, where applicable, are interchangeable and may be used in a selected embodiment even if not specifically shown or described. The same may also vary in many ways. These variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. An axial flux motor with reduced spatial harmonics, comprising: a first rotor including a plurality of magnets; a second rotor including a plurality of magnets; a rotor shaft coupled to the first rotor and the second rotor and defining a rotation axis, the first rotor and the second rotor being configured to rotate about the rotation axis; a stator having a first side, an opposite second side, and a stator body, the first side facing the first rotor and defining a first axially extending air gap therebetween, the opposite second side facing the second rotor and defining a second axially extending air gap therebetween, the stator body extending between the first side and the opposite second side, wherein the stator is stationary and includes a plurality of electromagnetic components defining a plurality of magnetic poles, the first side of the stator defining a first plurality of posts extending from the stator body in a first axial direction and a first plurality of slots disposed between the first plurality of posts, the second side of the stator defining a second plurality of posts extending from the stator body in a second axial direction opposite to the first axial direction and a second plurality of slots disposed between the second plurality of posts; and a plurality of distributed conductive windings disposed in non-adjacent slots of the first plurality of slots and the second plurality of slots, and each of the plurality of distributed conductive windings spanning the stator body from the first side to the second side of the stator, wherein each of the plurality of distributed conductive windings has a winding pitch span greater than or equal to 3 slots to less than or equal to 20 slots, wherein the winding pitch span of each of the plurality of distributed conductive windings is the same, and wherein spatial harmonics of orders less than or equal to the fundamental harmonic frequency are eliminated in the axial flux motor and spatial harmonics of orders greater than the fundamental harmonic frequency are reduced.

2. The axial flux motor according to claim 1, wherein, each of the plurality of distributed conductive windings has a winding pitch span greater than or equal to 3 slots to less than or equal to 10 slots, and the axial flux motor optionally includes: each of the corresponding slots of the plurality of slots has a maximum number of 10 conductive windings; a slot staggering amount greater than or equal to 1 and less than or equal to 8; and / or the number of the plurality of magnetic poles is greater than or equal to 2 to less than or equal to 30.

3. The axial flux motor according to claim 1, wherein, spatial harmonics of orders less than or equal to the fundamental harmonic frequency are eliminated in the axial flux motor, and spatial harmonics of orders greater than the fundamental harmonic frequency are reduced by greater than or equal to 50%.

4. The axial flux motor according to claim 1, wherein, both the first plurality of slots and the second plurality of slots include greater than or equal to 12 slots to less than or equal to 96 slots.

5. The axial flux motor according to claim 1, wherein, The number of the plurality of magnetic poles is 8, the pitch of the plurality of magnetic poles is 6 degrees, the first plurality of slots and the second plurality of slots each include 48 slots, each slot has two layers of conductive windings, the number of conductive windings in each slot is 2, and the slot misalignment amount is 1 slot.

6. The axial flux motor according to claim 1, wherein, the axial flux motor is a three-phase motor and includes a three-phase distributed conductive winding.

7. The axial flux motor according to claim 1, wherein, the stator includes an insulating metal strip, and the insulating metal strip is wound into an annular shape, and the annular shape defines the plurality of columns and the plurality of slots.

8. An axial flux motor having reduced space harmonics, comprising: two disk-shaped rotors, each of which includes a plurality of magnets; a rotor shaft coupled to the two disk-shaped rotors and defining a rotation axis, and the disk-shaped rotors are configured to rotate about the rotation axis; a disk-shaped stator disposed between the two disk-shaped rotors, wherein the disk-shaped stator is stationary and has a first side, an opposite second side, and a stator body extending between the first side and the opposite second side in an axial direction, the first side of the disk-shaped stator defines a first plurality of columns and a first plurality of slots extending from the stator body in a first axial direction, the first plurality of slots includes greater than or equal to 12 to less than or equal to 96 slots, the second side of the disk-shaped stator defines a second plurality of columns and a second plurality of slots extending from the stator body in a second axial direction opposite to the first axial direction, the second plurality of slots includes greater than or equal to 12 to less than or equal to 96 slots; a first axially extending air gap defined between the first of the disk-shaped rotors and the first side of the disk-shaped stator; a second axially extending air gap defined between the second of the disk-shaped rotors and the second side of the disk-shaped stator; a plurality of distributed conductive windings disposed in non-adjacent slots of the first plurality of slots and the second plurality of slots, and each of the plurality of distributed conductive windings spans the stator body between one of the first plurality of slots and a non-adjacent one of the second plurality of slots; and a plurality of electromagnetic components defining a plurality of magnetic poles, wherein the plurality of electromagnetic components are defined by the disk-shaped stator and the plurality of distributed conductive windings, wherein each of the plurality of distributed conductive windings has a winding pitch span of greater than or equal to 3 to less than or equal to 20 slots, and wherein the winding pitch span of each of the plurality of distributed conductive windings is the same, and wherein space harmonics of orders less than or equal to the first harmonic frequency are eliminated in the axial flux motor and space harmonics of orders greater than the first harmonic frequency are reduced.

9. The axial flux motor according to claim 8, wherein, space harmonics of orders less than or equal to the first harmonic frequency are eliminated in the axial flux motor, and space harmonics of orders greater than the first harmonic frequency are reduced by greater than or equal to 50%.

10. The axial flux motor according to claim 8, wherein, the number of the plurality of magnetic poles is 8, the pitch of the plurality of magnetic poles is 6 degrees, both the first plurality of slots and the second plurality of slots include 48 slots, each slot has two layers of conductive windings, the number of conductive windings in each slot is 2, and the slot stagger amount is 1 slot.

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