Stator and rotor design for cyclic torque requirements

Abstract

A motor or generator is disclosed that includes a rotor and a stator, the rotor having an axis of rotation and configured to generate a first magnetic flux parallel to the axis of rotation, the stator configured to generate a second magnetic flux parallel to the axis of rotation, and at least one of the rotor or stator configured to generate a non-uniformly distributed magnetic flux profile about the axis of rotation. A method is also disclosed that involves non-uniformly distributing one or more flux-generating windings of the stator about the axis of rotation of the rotor of an axial flux motor or generator.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 62 / 754,051, filed November 1, 2018, and entitled “PLANAR STATOR AND ROTOR DESIGN FOR PERIODIC TORQUE REQUIREMENTS.” This application is a continuation-in-part of U.S. patent application Ser. No. 16 / 378,294, entitled “STRUCTURES AND METHODS FOR CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS,” filed April 8, 2019, which claims the benefit under 35 U.S.C. § 120 of U.S. patent application Ser. No. 16 / 165,745, entitled “STRUCTURES AND METHODS FOR CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS,” filed October 19, 2018, now U.S. Patent No. 10,256,690, which claims the benefit under 35 U.S.C. § 120 of U.S. patent application Ser. No. 16 / 165,745, entitled “PLANAR COMPOSITE STRUCTURES AND METHODS FOR CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS,” filed December 22, 2017, now U.S. Patent No. 10,170,953, which claims the benefit under 35 U.S.C. No. 15 / 852,972, entitled "STACKING SUBASSEMBLIES IN PLANAR COMPOSITE STATORS TO OBTAIN HIGHER WORKING VOLTAGES," filed on July 10, 2017, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62 / 530,552, entitled "STRUCTURES AND METHODS OF CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS," filed on June 1, 2017, now U.S. Patent No. 9,859,763, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 15 / 611,359, entitled "STRUCTURES AND METHODS FOR CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS," filed on June 1, 2017, now U.S. Patent No. 9,859,763, which claims the benefit under 35 U.S.C.§120, which (A) is a continuation-in-part of U.S. patent application Ser. No. 15 / 283,088, entitled “STRUCTURES AND METHODS FOR CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS,” filed on September 30, 2016, now U.S. Patent No. 9,800,109, which claims the benefit under 35 U.S.C. §120, which (B) is a continuation-in-part of U.S. patent application Ser. No. 15 / 199,527, entitled “STRUCTURES AND METHODS FOR THERMAL MANAGEMENT IN PRINTED CIRCUIT BOARD STATORS,” filed on June 30, 2016, now U.S. Patent No. 9,673,684, which also claims the benefit under 35 U.S.C. §120, which (C) is a continuation-in-part of U.S. patent application Ser. No. 15 / 283,088, entitled “STRUCTURES AND METHODS FOR CONTROLLING LOSSES IN PRINTED CIRCUIT BOARDS,” filed on October 2, 2015, now U.S. Patent No. 9,673,684, which claims the benefit under 35 U.S.C. No. 62 / 236,407, entitled "PRINTED CIRCUIT BOARD WINDINGS," filed on October 2, 2015, and (2) U.S. Provisional Patent Application No. 62 / 236,422, entitled "STRUCTURES FOR THERMAL MANAGEMENT IN PRINTED CIRCUIT BOARD STATORS," which (B) is a continuation-in-part of U.S. Patent Application No. 15 / 208,452, entitled "APPARATUS AND METHOD FOR FORMING A MAGNET ASSEMBLY," filed on July 12, 2016, now U.S. Patent No. 9,673,688, which claims the benefit under 35 U.S.C. § 120 of such application, which (C) is a continuation-in-part of U.S. Patent Application No. 15 / 208,452, entitled "APPARATUS AND METHOD FOR FORMING A MAGNET ASSEMBLY," filed on January 6, 2016, now U.S. Patent No. 9,673,688, which claims the benefit under 35 U.S.C. § 120 of such application, which (D) is a continuation-in-part of U.S. Patent Application No. 15 / 208,452, entitled "APPARATUS AND METHOD FOR FORMING A MAGNET ASSEMBLY," filed on January 6, 2016, now U.S. Patent No. 9,673,688, No. 62 / 275,653, entitled "AXIAL FLUX MACHINES WITH GENERALLY PLANAR WINDINGS," 35 U.S.C.§ 119(e) benefit. This application is also a continuation-in-part of U.S. patent application Ser. No. 15 / 983,985, filed May 18, 2018, and published as U.S. Patent Application Publication No. US 2018 / 0351441, entitled “PRE-WARPED ROTORS FOR CONTROL OF MAGNET-STATOR GAP IN AXIAL FLUX MACHINES”, which claims the benefit under 35 U.S.C. § 120 of each of (1) U.S. Provisional Patent Application No. 62 / 515,251, filed June 5, 2017, entitled “PRE-WARPED ROTORS FOR CONTROL OF MAGNET-STATOR GAP IN AXIAL FLUX MACHINES”, and (2) U.S. Provisional Patent Application No. 62 / 515,256, filed June 5, 2017, entitled “AIR CIRCULATION IN AXIAL FLUX MACHINES”. The benefit of this application under USC § 119(e) is claimed. The contents of each of the foregoing applications, publications, and patents are hereby incorporated by reference in their entirety for all purposes. [Background technology]

[0002] Permanent magnet axial flux motors and generators described by several patents, including U.S. Pat. No. 7,109,625 ("the '625 patent"), feature a generally planar printed circuit board stator (PCS) interposed between magnets featuring alternating north-south poles. These printed circuit board stators, when supported from the outer edge of the stator to a fixed frame, have holes through which the shaft connecting the rotor passes. An alternative embodiment is to swap the roles of the inner and outer radii, resulting in a situation where the inner radius of the stator is supported and the rotor encases the stator. The shaft is effectively moved to the outer radius in this configuration, sometimes referred to as the "outer runner." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,109,625 Summary of the Invention [Means for solving the problem]

[0004] The present invention provides, for example, the following: (Item 1) A motor or a generator, the motor or the generator comprising: a rotor having an axis of rotation, the rotor configured to generate a first magnetic flux parallel to the axis of rotation; a stator configured to generate a second magnetic flux parallel to the axis of rotation; Equipped with A motor or generator, wherein at least one of the rotor or the stator is configured to generate a non-uniformly distributed magnetic flux profile about the axis of rotation. (Item 2) 2. The motor or generator of claim 1, wherein the rotor is configured to generate a first magnetic flux profile that is non-uniformly distributed about the axis of rotation. (Item 3) 3. A motor or generator as described in item 2, wherein the rotor comprises one or more magnet segments non-uniformly distributed around the axis of rotation. (Item 4) 4. The motor or generator of claim 3, wherein each of the one or more magnet segments has a respective surface location at which the first magnetic flux has a maximum density, the respective surface locations being non-uniformly distributed around the axis of rotation. (Item 5) 3. The motor or generator of claim 2, wherein the rotor is configured such that as the rotor rotates through a range of angles relative to the stator at a substantially constant speed, the periodicity of the torque generated due to the interaction of the first magnetic flux and the second magnetic flux is irregular. (Item 6) 3. The motor or generator of claim 2, wherein the stator is configured to generate a second magnetic flux profile that is non-uniformly distributed about the axis of rotation. (Item 7) 2. The motor or generator of claim 1, wherein the stator is configured to generate a non-uniformly distributed magnetic flux profile about the axis of rotation. (Item 8) 8. The motor or generator of claim 7, wherein the stator comprises one or more printed circuit board segments non-uniformly distributed around the axis of rotation. (Item 9) 2. The motor or generator of claim 1, wherein the stator comprises conductive traces disposed on at least one dielectric layer to generate the second magnetic flux upon application of a current. (Item 10) 10. The motor or generator of claim 9, wherein the stator is configured such that at any given time when the conductive traces have current applied to them, one or more locations of maximum density of the second magnetic flux are non-uniformly distributed about the axis of rotation. (Item 11) 11. The motor or generator of claim 10, wherein the conductive traces are disposed on the at least one dielectric layer and coupled to a power source to generate three phases of the second magnetic flux corresponding to three phases of a current output by the power source. (Item 12) 11. The motor or generator of item 10, wherein the stator comprises one or more printed circuit board segments non-uniformly distributed around the axis of rotation. (Item 13) 2. The motor or generator of claim 1, wherein at least one of the rotor or the stator is configured such that as the rotor rotates through a range of angles relative to the stator at a constant speed, the periodicity of the torque generated due to the interaction of the first magnetic flux and the second magnetic flux is irregular. (Item 14) 1. A method, the method comprising: disposing one or more flux generating windings of a stator non-uniformly about an axis of rotation of a rotor of an axial flux motor or generator. (Item 15) 15. The method of claim 14, wherein disposing the one or more flux generating windings comprises disposing one or more printed circuit board segments containing the windings non-uniformly about the axis of rotation. (Item 16) Item 16. The method of item 15, wherein the rotor comprises magnets arranged non-uniformly around the axis of rotation. (Item 17) Item 16. The method of item 15, wherein arranging the one or more printed circuit board segments further comprises arranging the one or more printed circuit board segments such that, at any given time when the winding has current applied to it, one or more locations of maximum density of the second magnetic flux are non-uniformly distributed about the axis of rotation. (Item 18) 15. The method of claim 14, wherein arranging the one or more flux generating windings includes arranging the one or more flux generating windings such that as the rotor rotates through a range of angles relative to the stator at a constant speed, a periodicity of torque generated due to interaction of magnetic flux generated by the rotor and the stator is irregular. (Item 19) 1. A rotor for use in a motor or generator, the rotor comprising: A support structure; One or more magnet segments Equipped with a rotor, the one or more magnet segments being supported by the support structure, the one or more magnet segments, when assembled with a stator, generating a first magnetic flux parallel to an axis of rotation about which the support structure rotates, the stator generating a second magnetic flux parallel to the axis of rotation, the one or more magnet segments being constructed and arranged to generate a magnetic flux profile that is non-uniformly distributed about the axis of rotation. (Item 20) 20. The rotor of claim 19, wherein the one or more magnet segments include at least a first magnet segment and a second magnet segment spaced apart from the first magnet segment, the first magnet segment including a greater number of adjacent magnets than the second magnet segment. Objects, aspects, features, and advantages of the embodiments disclosed herein will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings, in which like reference numbers identify similar or identical elements. Reference numbers introduced herein in connection with the figures may be repeated in one or more subsequent figures without additional description herein to provide context for other features, and not all elements may be labeled in every figure. The drawings are not necessarily to scale, with emphasis instead being placed on illustrating embodiments, principles, and concepts. The drawings are not intended to limit the scope of the claims contained herewith. [Brief description of the drawings]

[0005] [Figure 1A] FIG. 1A illustrates an example of an axial flux motor or generator in which aspects of the present disclosure may be employed.

[0006] [Figure 1B]FIG. 1B is an enlarged view showing components of the axial flux motor or generator shown in FIG. 1A and a means for assembling such components.

[0007] [Diagram 2] FIG. 2 is a conceptual diagram showing three printed circuit board stators having equal areas but different configurations.

[0008] [Diagram 3] FIG. 3 is a schematic diagram showing how multiple stator segments can be arranged for manufacture on a standard sized printed circuit board panel.

[0009] [Figure 4] FIG. 4 is a schematic diagram showing what a subset of the stator segments shown in FIG. 3 would look like if they were arranged edge-to-edge on the circuit board panel shown in FIG.

[0010] [Diagram 5] FIG. 5 illustrates an example arrangement of stator segments relative to magnets on a rotor in accordance with some aspects of the disclosure.

[0011] [Figure 6] FIG. 6 shows the same arrangement as FIG. 5, but the rotor is shown at an angle where the stator segments overlap the magnet sections that provide peak torque.

[0012] [Figure 7] FIG. 7 illustrates an example arrangement of multiple stator segments relative to magnets on a rotor in accordance with some aspects of the disclosure.

[0013] [Figure 8] FIG. 8 illustrates a cross section of an example embodiment of an axial flux motor configured and integrated with a washing machine load in accordance with some aspects of the disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Summary of the invention) This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. It is not intended to identify key features or critical elements, nor is it intended to limit the scope of the claims included herewith. In some of the disclosed embodiments, the motor or generator includes a rotor and a stator, the rotor having an axis of rotation and configured to generate a first magnetic flux parallel to the axis of rotation, the stator configured to generate a second magnetic flux parallel to the axis of rotation, and at least one of the rotor or stator configured to generate a magnetic flux profile that is non-uniformly distributed about the axis of rotation. In other disclosed embodiments, a method involves non-uniformly disposing one or more flux generating windings of a stator about the axis of rotation of a rotor of an axial flux motor or generator. In still other disclosed embodiments, a rotor for use in a motor or generator comprises a support structure and one or more magnet segments supported by the support structure, the one or more magnet segments generating a first magnetic flux parallel to an axis of rotation, the support structure when assembled with a stator rotates about the axis of rotation, the stator generating a second magnetic flux parallel to the axis of rotation, and the one or more magnet segments configured and arranged to generate a magnetic flux profile that is non-uniformly distributed about the axis of rotation. (Detailed Description)

[0015] In existing axial flux motors or generators, such as those disclosed in U.S. Pat. Nos. 7,109,625, 9,673,688, 9,800,109, 9,673,684, and 10,170,953, and U.S. Patent Application Publication No. 2018-0351441 A1 (the "'441 Publication"), the entire contents of each of which are incorporated herein by reference, the flux-generating components of the stator, whether comprised of a single continuous printed circuit board or multiple printed circuit board segments, are positioned such that at any given time when the stator windings have current applied to them, the location of the peak magnetic flux generated by the stator is uniformly distributed with respect to angle about the axis of rotation of the rotor. Similarly, in such machines, the flux generating components of the rotor, whether consisting of ring magnets or individual magnets arranged in pockets, are also arranged such that the locations of peak flux generated by the rotor at any given time are similarly uniformly distributed with respect to angle about the rotor's axis of rotation. Thus, in all such machines, at any given time that the machine is in operation, the locations of peak flux generated by each of the rotor and stator are uniformly distributed as a function of angle about the machine's axis of rotation. In other words, for each of the rotors and stators in such machines, the same angle separates each location of peak flux from the next adjacent location of peak flux about the axis of rotation, whereby the flux profile of each of the rotors and stators is uniformly distributed about the axis of rotation.

[0016] Disclosed herein are alternative designs that have cost advantages over conventional designs for certain loads and machine configurations, where the stator and / or rotor may instead be configured to have a flux profile that is non-uniformly distributed around the rotor's axis of rotation. In some embodiments, for example, the stator may be configured such that it describes a portion of an arc that encompasses the machine's main axis. If such a stator segment can be positioned at a larger radius compared to a stator of equal area that is uniformly distributed around the same axis, due to integration with the machine and attached load, the torque generated may be proportional to the increase in radius at which the stator segment is located, assuming equal flux in the gap and current density limitations in the stator. However, the cost of maintaining equal flux in the gap for an "off-center" stator segment is an increase in magnet volume that is inversely proportional to the angle subtended by that segment. This is not a desirable tradeoff in most cases. However, in applications where peak torque is desired at a particular angle or range of shaft angles, the magnet material may be distributed non-uniformly relative to the rotor, thereby exposing the stator to peak flux density at the shaft angle where peak torque is desired. For generator applications where the source has periodic torque production capability, machines designed according to this principle may offer similar advantages.

[0017] The design of the stator and magnet system to produce peak torque at a particular angle is not limited to one concentration of magnetic material on one stator segment and / or rotor, although this is the simplest embodiment. An embodiment including one or more non-uniformly distributed stator segments and / or one or more non-uniformly distributed magnet segments may provide a useful combination of torque capabilities as a function of angle. It should be understood that the same or similar torque capabilities as a function of angle may be achieved using different combinations of one or more non-uniformly distributed stator segments and one or more non-uniformly distributed magnet segments. For example, the same or similar torque capabilities as a function of angle can be achieved by swapping the distribution of stator segments vs. rotor magnet locations. This may allow the designer to make a trade-off in magnet material cost and stator area while maintaining the same or similar torque capabilities as a function of angle.

[0018] Designing a machine to produce peak torque at a particular angle does not prevent continuous rotation. When continuous rotation is desired, a machine designed according to the principles disclosed herein can deliver torque (at the peak torque angle) in a series of pulses smoothed by the moment of inertia of the attached load to provide a nearly constant speed. The advantage of this design is that when the stator does not overlap with the magnets, stator losses due to eddy currents can be zero. Another possibility for continuous rotation is to distribute the magnets such that the stator segments always experience magnetic flux, but at a magnitude less than the "peak torque" angle.

[0019] Some embodiments described herein may be particularly advantageous for applications where the machine radius can be greatly increased compared to conventional designs. In these applications, planar circuit board stator (PCS) segments arranged at a larger radius than a uniform planar circuit board stator may achieve higher peak torque per unit area of ​​the stator. Furthermore, compared to a thin annular stator at a large radius, the stator segments can be "tiled" or arranged on a standard size printed circuit board "panel". This may allow for more efficient utilization of printed circuit board material and reduce associated machine costs.

[0020] Examples of application areas include reciprocating piston or diaphragm type pumps, which may have cyclic torque requirements. For balancing purposes, these machines frequently include an off-center mass, which could potentially be replaced by an asymmetrically designed rotor. Similarly, generators coupled to single piston engines could benefit from the co-design of a balance mass with magnetic material in a stator segment type generator. Other potential applications include washing machines or other applications where the motor or generator moves through a limited angle, and cyclic or "reversing" type loads.

[0021] The fundamental observation of the novel concept disclosed herein can be summarized in a discussion of "scaling" for otherwise equivalent stators or stator segments, independent of the internal organization and connections of the stators, based on fundamental design considerations. In a conventional annular PCS conforming to the description in the '625 patent, the torque can be expressed as:

number

[0022] The components of this equation include integrals from a first radius r1 to a second radius r2 that includes the active area of ​​the stator. The integrals cover a complete annulus by limiting the integral with respect to θ. The term rdrdθ is an infinitesimal area element, and rfdens is the magnitude of the torque density corresponding to the equation τ=rxF. The force density is in the θ direction due to the axial flux and radial current density, i.e.,

number

[0023] Here, the force density is the product of the current density supported by the stator and the magnetic flux density resulting from the rotor magnet circuit and the stator reaction at that current density. For illustration purposes, B is assumed to be radial. In a stator designed according to the '625 patent, the diverging radial traces effectively introduce a 1 / r decrease in current density from the inner radius r1. A model that captures this effect is:

number

[0024] where J0 is the maximum supportable current density based on feature interference for a given copper weight at the inner radius, via size, and clearance requirements.

number

[0025] The area A of a stator or stator segment with an angular extent δ is:

number

[0026] For stators of conventional design, δ=2π. For stator segments, δ ideally corresponds to the total number of pole pairs. For purposes of comparison between stator segments and conventional designs based on cost, it is reasonable to compare stators and magnet assemblies of equal area. Because the inner radius r1 is increased and is now considered an independent variable, multiple solutions for δ and r2 exist for any r1. In particular, considering δ, the pole spacing across the segments does not need to conform to the usual constraint of evenly distributing the poles across 2π radians as in conventional stators. This suggests considerable design flexibility for the segments and the ability to achieve equal area A not enjoyed by conventional stators. Examples of advantages of displacing stator area to a larger r with a compact δ include: (1) stator segments with a larger r result in higher peak torque per unit area; (2) peak torque is available when the stator segments and magnetic material completely overlap at a particular rotor angle (or angle range); (3) there are no eddy current losses in the machine when the magnetic material and stator do not overlap; (4) stator segments can be obtained when r, r and δ are such that the segments can be "nested" on a printed circuit board panel, minimizing wasted material and cost; and (5) peak torque per unit area (or per unit cost) increases with the radius of the stator segments.

[0027] Specific torque τ pGiven the design procedure for a prototype conventional stator with δ=2π satisfying

number

[0028] The combination of stator segments and magnetic material concentrated at specific angles on the fixed frame and rotor can achieve different torque capabilities as a function of angle. One or more areas on the rotor can support magnetic material with different magnetic flux densities, one or more pole pairs, and one or more areas on the rotor can be distributed at different angles. There can be one or more stator segments positioned at different angles within the fixed frame.

[0029] Examples of motor and / or generator designs in which non-uniformly distributed stators and / or rotors such as those disclosed herein may be employed are described in U.S. Patent Nos. 7,109,625, 9,673,688, 9,800,109, 9,673,684, and 10,170,953, and U.S. Patent Application Publication No. 2018-0351441 A1 ("the '441 publication") (incorporated by reference above). An illustrative example of such a machine will first be described in connection with FIGS. 1A and 1B. Examples of stators and rotors having non-uniformly distributed magnetic flux profiles about the rotor's axis of rotation that may be employed in such machines will then be described in connection with FIGS. 2-8.

[0030] FIG. 1A shows an example of a system 100 employing a planar compound stator 110 in assembly with rotor components 104a and 104b, shaft 108, wires 114, and controller 112. A close-up view showing these components and the means for their assembly is shown in FIG. 1B. The pattern of magnetic poles in the permanently magnetized portions 106a, 106b of the rotor assembly is also evident in the close-up view of FIG. 1B. FIG. 1A is an example of an embodiment in which the electrical connection 114 is employed at the outer radius of the PCS 110 and the stator is mounted to a frame or case at the outer periphery. Another useful configuration, the "outer runner" configuration, involves mounting the stator at the inner radius, making the electrical connection 114 at the inner radius, and replacing the shaft 108 with an annular ring that separates the rotor halves. It is also possible to configure the system with only one magnet, either 106a or 106b, or to insert multiple stators between consecutive magnet assemblies. The wires 114 may also carry information about the position of the rotor based on the readings of a Hall effect or similar sensor mounted on the stator. Although not shown, for a similar purpose, an encoder attached to the shaft 108 may provide position information to the controller 112.

[0031] 1A and 1B can function as either a motor or a generator, depending on the operation of the controller 112 and the components connected to the shaft 108. As a motor system, the controller 112 operates the switches such that current in the stator 110 generates torque about the shaft due to magnetic flux in the gap resulting from magnets 104a, 104b connected to the shaft 108. Depending on the design of the controller 112, the magnetic flux in the gap and / or the position of the rotor can be measured or estimated to operate the switches to achieve a torque output at the shaft 108. As a generator system, a source of mechanical rotational power connected to the shaft 108 generates voltage waveforms at the terminals 112 of the stator. These voltages can be applied directly to a load or they can be rectified using a three-phase (or multi-phase) rectifier in the controller 112. The rectifier implementation 112 can be "self-commutated" using diodes in a generator mode, or can be constructed using controlled switches in a motor controller that is operated such that the shaft torque opposes the torque provided by a mechanical source and mechanical energy is converted to electrical energy. Thus, the same configuration of FIG. 1A can function as both a generator and a motor depending on how the controller 112 is operated. In addition, the controller 112 can include filter components that mitigate switching effects, reduce EMI / RFI from the wires 114, reduce losses, and provide additional flexibility in the power supplied to or delivered from the controller.

[0032] FIG. 2 shows the geometry of three stators 202, 204, 206 with equal area but different angles and radial extents. Stators 204 and 206 have different inside radii. Stator 206 shows relative dimensions typical of a stator as described by the '625 patent. Stator 204 is a thin annular design. In stator 204, the inside radius has been increased, but a stator with these relative dimensions does not efficiently utilize the "panel" of printed circuit board material. Stator 202 shows a stator segment 208 of equal area and equivalent radius as stator 204 as proposed herein. Other things being equal, at a larger radius, stators 202 and 204 will produce higher peak torque than stator 206 because the radius increases the torque arm.

[0033] FIG. 3 shows a diagram of a standard size printed circuit board panel 302. 2 3 illustrates the "panelization" or packing of stator segments, such as the segments 208 shown in FIG. 3. Effective utilization of the panels 302 is high in the arrangement shown. The cost of the stator segments 208 is inversely proportional to the utilization of the panels 302.

[0034] Figure 4 shows an inefficient arrangement of segments 208 of the same size in panel 302 as in Figure 3. Although this arrangement is not practical, it shows the efficient panel utilization that would be achieved for a conventional stator with the same inner and outer radii as those achieved by segments 208.

[0035] FIG. 5 shows an example arrangement of stator segments 208 relative to magnets 502 on a rotor 504. In the illustrated example, a high density angular range 506 on the rotor 504 of magnets 502, also referred to herein as the "high density magnet area", is provided to achieve peak torque at an angle of overlap with stator segments 208. A low density angular range 508 of magnets 502, also referred to herein as the "low density magnet area", is arranged to provide a lower torque capability independent of angle. Although not shown, it should be understood that in some embodiments, non-magnetic elements may be added near the low density magnet area 508 to balance the weight of the rotor 504 as a whole. Furthermore, it should be understood that in some embodiments, an additional rotor portion (not shown) of opposite polarity but having a corresponding magnet arrangement may be positioned above the illustrated portion of the rotor 504, such that the stator segments 208 may be positioned in the gap between the two rotor portions, with magnetic flux lines extending in a direction parallel to the axis of rotation of the rotor between opposing pairs of magnets of opposite polarity. Additionally, although not shown in FIG. 5, it should be understood that the stator segments 208 may include conductive traces and / or vias (e.g., disposed on one or more dielectric layers) that, when energized, are configured to form windings that generate magnetic flux in a direction parallel to the axis of rotation of the rotor. Such windings may be configured to receive one or more phases of current from a power supply (not shown in FIG. 5) to generate such magnetic flux, and such windings may be arranged in one or more spirals, in one or more serpentine patterns, or otherwise.

[0036] As shown in FIG. 5, in some embodiments, the stator segments 208 may be held in place via arcuate mounting members 510 to which the stator segments 208 may be attached using one or more fasteners 512, and one or more windings (not shown) of the stator segments 208 may be connected to terminals 514 associated with the mounting members 510 to supply an applied current to the windings, which may be connected to a controller (not shown in FIG. 5), such as the controller 112 discussed above in connection with FIGS. 1A and 1B.

[0037] FIG. 6 shows the same configuration as FIG. 5, but with the rotor 504 positioned at an angle where the stator segments 208 overlap the high density magnet sections 506 that provide peak torque.

[0038] 7 shows an alternative arrangement to those of FIGS. 4 and 5. As shown, in addition to or instead of employing low density magnet regions 508 (not shown in FIG. 7) along with high density angular ranges 506, the stator segments 208 ag can be arranged such that they completely or nearly trace the annular stator with constant available torque at any angle. 208 Some of the ag may be made smaller, may be arranged with a coarser pitch, may include fewer winding "turns," and / or may be different from one or more of the other stator segments. 208 Less power can be supplied, thereby providing angle specific peak torque, while machines with concentrated magnets still provide torque capability at any angle. For example, in some embodiments, the stator segments 208 a is for such purposes another stator segment 208 bg may be configured, positioned, and / or applied differently.

[0039] Regardless of the particular arrangement of magnets 502 and stator segments 208 employed, care may be taken to ensure that, at least in some circumstances, during rotation of the rotor 504, at least one stator segment 208 at least partially overlaps at least one magnet 502 at each position, thereby preventing the rotor 504 from becoming "stuck" in a position where no magnetic flux from the stator segments 208 interacts with the magnetic flux from the magnets 502.

[0040] In each of the exemplary configurations described above, the stator segments 208 and / or the magnets 502 of the rotor 504 are configured to have a magnetic flux profile that is non-uniformly distributed about the primary axis of rotation of the machine. Ta's The magnets 502 of the rotor 504 are arranged such that at any given time when the windings are energized, the locations of the peak magnetic flux generated by the stator are non-uniformly distributed with respect to angles about the rotor's axis of rotation. Similarly, in such a machine, the magnets 502 of the rotor 504 are arranged such that at any given time, the locations of the peak magnetic flux generated by the rotor are similarly non-uniformly distributed with respect to angles about the rotor's axis of rotation. Thus, for each of the rotors and stators in such a machine, different angles separate some locations of peak magnetic flux from adjacent locations of peak magnetic flux about the axis of rotation such that the magnetic flux profile generated by such components is non-uniformly distributed about the axis of rotation.

[0041] FIG. 8 illustrates a cross-section of an exemplary embodiment of an axial flux motor 802 configured with components such as those shown in FIGS. 5 and 6 and integrated with a washing machine load 804 in accordance with some aspects of the disclosure. As shown, the stator segments 208 of the motor 802 may be secured to a housing 806 including a washing machine tub 808 via mounting members 510 and one or more fasteners 512, which may be rotatably coupled to the housing 806 via bearing elements 810. The rotor 504 of the motor 802 may directly drive the washing machine tub 808 via a shaft 812 that may extend from and / or be fixedly attached to the washing machine tub 808. In the illustrated configuration, continuous rotation at relatively high speeds and low torque in a "fast spin" mode may be achieved using the stator segments 208 and a collection of magnets 502 disposed in a high density magnet region 506 and one or more low density magnet regions 508, as described above in connection with FIGS. 5 and 6. During such a fast rotation mode, as the rotor 504 rotates through a range of angles relative to the stator segments 208 at a substantially constant speed due to the uneven distribution of the rotor and stator magnetic flux profiles about the rotor's axis of rotation, the periodicity of the torque generated due to the interaction between the magnetic flux generated by the rotor and stator is irregular. The reversing action required for the "wash" mode may be a relatively low speed, high torque mode of operation where torque may be delivered at a specific angle. In this case, the interaction of the stator segments 208 with the high density magnet regions 506 may provide the peak torque requirement. Exemplary implementations of the apparatus and methods according to the present disclosure

[0042] Paragraphs (A1)-(A14) below describe examples of apparatus that may be implemented in accordance with the present disclosure.

[0043] (A1) A motor or generator may include a rotor having an axis of rotation and configured to generate a first magnetic flux parallel to the axis of rotation, and a stator configured to generate a second magnetic flux parallel to the axis of rotation, at least one of the rotor or stator configured to generate a magnetic flux profile that is non-uniformly distributed about the axis of rotation.

[0044] (A2) The motor or generator may be configured as described in paragraph (A1), and the rotor may be further configured to generate a first magnetic flux profile that is non-uniformly distributed about the axis of rotation.

[0045] (A3) The motor or generator may be configured as described in paragraph (A2), and the rotor may further comprise one or more magnet segments non-uniformly distributed around the axis of rotation.

[0046] (A4) The motor or generator may be configured as described in paragraph (A3), and each of the one or more magnet segments may further have a respective surface location at which the first magnetic flux has a maximum density, and the respective surface locations may be non-uniformly distributed around the axis of rotation.

[0047] (A5) The motor or generator may be configured as described in any of paragraphs (A2)-(A4), and the rotor may be further configured such that as the rotor rotates through a range of angles relative to the stator at a substantially constant speed, the periodicity of the torque generated due to interaction of the first magnetic flux and the second magnetic flux is irregular.

[0048] (A6) The motor or generator may be configured as described in any of paragraphs (A2)-(A5), and the stator may be further configured to generate a second magnetic flux profile non-uniformly distributed about the axis of rotation.

[0049] (A7) The motor or generator may be configured as described in paragraph (A1), and the stator may be further configured to generate a magnetic flux profile that is non-uniformly distributed about the axis of rotation.

[0050] (A8) The motor or generator may be configured as described in any of paragraphs (A2)-(A7), and the stator may further comprise one or more printed circuit board segments non-uniformly distributed around the axis of rotation.

[0051] (A9) The motor or generator may be configured as described in any of paragraphs (A2)-(A8), wherein the stator further comprises a conductive trace disposed on the at least one dielectric layer and may generate a second magnetic flux upon application of a current.

[0052] (A10) The motor or generator may be configured as described in any of paragraphs (A2)-(A9), and the stator may be further configured such that, at any given time when the conductive traces have current applied to them, one or more locations of maximum density of the second magnetic flux are non-uniformly distributed about the axis of rotation.

[0053] (A11) A motor or generator may be configured as described in paragraph (A9) or paragraph (A10), wherein the conductive traces are disposed on at least one dielectric layer and coupled to a power source to generate three phases of a second magnetic flux corresponding to the three phases of a current output by the power source.

[0054] (A12) The motor or generator may be configured as described in any of paragraphs (A1)-(A11), and the stator may be further configured such that as the rotor rotates through a range of angles relative to the stator at a constant speed, the periodicity of the torque generated due to interaction of the first magnetic flux and the second magnetic flux is irregular.

[0055] (A13) A rotor for use in a motor or generator may comprise a support structure and one or more magnet segments supported by the support structure and generating a first magnetic flux parallel to the axis of rotation about which the support structure rotates when assembled with a stator generating a second magnetic flux parallel to the axis of rotation, the one or more magnet segments constructed and arranged to generate a magnetic flux profile that is non-uniformly distributed about the axis of rotation.

[0056] (A14) The rotor may be configured as described in paragraph A13, and the one or more magnet segments may further include at least a first magnet segment and a second magnet segment spaced apart from the first magnet segment, and the first magnet segment may include a greater number of adjacent magnets than the second magnet segment.

[0057] Paragraphs (M1)-(M5) below describe examples of methods that may be implemented according to the present disclosure.

[0058] (M1) The method may include disposing one or more flux generating windings of a stator non-uniformly about an axis of rotation of a rotor of an axial flux motor or generator.

[0059] (M2) The method may be performed as described in paragraph (M1), wherein disposing the one or more flux generating windings further includes non-uniformly disposing one or more printed circuit board segments including the windings about the axis of rotation.

[0060] (M3) The method may be performed as described in paragraph (M1) or paragraph (M2), and wherein arranging the one or more printed circuit board segments may further include arranging the one or more printed circuit board segments such that, at any given time when the winding has current applied to it, one or more locations of maximum density of the second magnetic flux are non-uniformly distributed about the axis of rotation.

[0061] (M4) The method may be carried out as described in any of paragraphs (M1)-(M3), and the rotor may include magnets that are non-uniformly arranged around the axis of rotation.

[0062] (M5) The method may be performed as described in any of paragraphs (M1)-(M4), and arranging the one or more flux generating windings may further include arranging the one or more flux generating windings such that as the rotor rotates through a range of angles relative to the stator at a constant speed, the periodicity of the torque generated due to interaction of magnetic flux generated by the rotor and stator is irregular.

[0063] Having thus described several aspects of at least one embodiment, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of this disclosure. Accordingly, the foregoing description and drawings are by way of example only.

[0064] Various aspects of the disclosure may be used alone, in combination, or in various arrangements not specifically discussed in the embodiments described above, and therefore this application is not limited to the details and arrangements of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0065] The disclosed aspects may also be embodied as a method, examples of which are provided. The acts performed as part of the method may be ordered in any suitable manner. Thus, while acts are shown as sequential acts in the illustrative embodiments, embodiments may be constructed in which acts are performed in an order different from that illustrated, which may include performing some acts simultaneously.

[0066] The use of ordinal terms such as "first," "second," "third," etc. to modify claim elements in the claims does not, by itself, imply any priority, precedence, or order of one claim element over another, or the chronological order in which acts of a method are performed, but rather merely distinguishes one claimed element having a certain name from another element having the same name (in the absence of the use of the ordinal terminology) and is used as a marker to distinguish the claim elements.

[0067] The phraseology and terminology used herein are also for purposes of description and should not be regarded as limiting. The use herein of "including," "comprising," "having," "including," "with," and variations thereof are meant to encompass the items listed thereafter and equivalents and additional items.

Claims

1. A motor or a generator, the motor or the generator comprising: a rotor having an axis of rotation, the rotor configured to generate a rotor flux parallel to the axis of rotation, a profile of the rotor flux varying circumferentially about the axis of rotation, the rotor further configured such that one or more locations at which the rotor flux has a peak value are distributed non-uniformly about the axis of rotation and with respect to the circumferential direction; a stator configured to generate a stator flux parallel to the axis of rotation that is different from the rotor flux; Equipped with 1. A motor or generator, wherein the profile of the stator flux varies in the circumferential direction about the axis of rotation, and the stator is further configured such that one or more locations at which the stator flux has a peak value are distributed non-uniformly around the axis of rotation and with respect to the circumferential direction.

2. 2. The motor or generator of claim 1, wherein the rotor comprises one or more magnet segments distributed circumferentially around the axis of rotation such that the one or more magnet segments are non-uniformly distributed as a function of angle around the axis of rotation, each of the one or more magnet segments generating a respective portion of the rotor magnetic flux.

3. 2. The motor or generator of claim 1, wherein the stator comprises one or more printed circuit board segments distributed circumferentially about the axis of rotation such that the one or more printed circuit board segments are non-uniformly distributed as a function of angle about the axis of rotation.

4. 10. The motor or generator of claim 1, wherein the stator comprises conductive traces disposed on at least one dielectric layer for generating one or more respective portions of the stator magnetic flux upon application of electric current thereto.

5. 5. The motor or generator of claim 4, wherein the conductive traces are disposed on the at least one dielectric layer and coupled to a power source to generate a rotating magnetic flux corresponding to a polyphase set of currents output by the power source.

6. 6. A motor or generator as claimed in any preceding claim, wherein the rotor and stator are configured such that as the rotor rotates at a constant speed through a range of angles relative to the stator, the periodicity of the torque generated due to interaction of the rotor magnetic flux with the stator magnetic flux is irregular.

7. 6. A motor or generator as claimed in any preceding claim, wherein the rotor and stator are configured to provide a torque capability between the rotor and stator that varies non-periodically as a function of the angular position of the rotor relative to the stator as the rotor rotates through a complete mechanical rotation about the axis of rotation.

8. the rotor includes at least first, second, and third magnets oriented to generate respective portions of the rotor magnetic flux in a first direction parallel to the axis of rotation; there are no other magnets angularly positioned between the first magnet and the second magnet and oriented to generate magnetic flux in the first direction; there are no other magnets angularly positioned between the second magnet and the third magnet and oriented to generate magnetic flux in the first direction; 6. A motor or generator as claimed in any preceding claim, wherein a first distance between the first magnet and the second magnet is at least twice a second distance between the second magnet and the third magnet.

9. the stator includes first, second, and third windings oriented to generate at least a respective portion of the stator magnetic flux in a second direction parallel to the axis of rotation when energized with a current of a first polarity; when a current of the first polarity is applied, there is no other winding angularly positioned between the first winding and the second winding that is oriented to generate magnetic flux in the second direction; when a current of the first polarity is applied, there is no other winding angularly positioned between the second winding and the third winding that is oriented to generate magnetic flux in the second direction; 9. The motor or generator of claim 8, wherein a third distance between the first winding and the second winding is at least twice a fourth distance between the second winding and the third winding.

10. a first portion of the rotor configured to generate a first peak magnetic flux density parallel to the axis of rotation at a first location relative to the rotor; a second portion of the rotor configured to generate a second peak magnetic flux density parallel to the axis of rotation at a second location relative to the rotor; the first portion of the stator is configured to generate a third peak magnetic flux density parallel to the axis of rotation at a third location relative to the stator; 6. A motor or generator as claimed in any preceding claim, wherein the rotor and the stator are configured such that a first torque capacity between the rotor and the stator when the first location is angularly aligned with the third location is greater than a second torque capacity between the rotor and the stator when the second location is angularly aligned with the third location.

11. 11. The motor or generator of claim 10, wherein the rotor and the stator are configured such that the first torque capacity when the first location is angularly aligned with the third location is at least 25 percent greater than the second torque capacity when the second location is angularly aligned with the third location.

12. 11. The motor or generator of claim 10, wherein the rotor and the stator are configured such that the first torque capacity when the first location is angularly aligned with the third location is at least twice the second torque capacity when the second location is angularly aligned with the third location.

13. a first portion of the stator configured to generate a first peak magnetic flux density parallel to the axis of rotation at a first location relative to the stator; a second portion of the stator configured to generate a second peak magnetic flux density parallel to the axis of rotation at a second location relative to the stator; the first portion of the rotor is configured to generate a third peak magnetic flux density parallel to the axis of rotation at a third location relative to the rotor; 6. A motor or generator as claimed in any preceding claim, wherein the rotor and the stator are configured such that a first torque capacity between the rotor and the stator when the first location is angularly aligned with the third location is greater than a second torque capacity between the rotor and the stator when the second location is angularly aligned with the third location.

14. 14. The motor or generator of claim 13, wherein the rotor and the stator are configured such that the first torque capacity when the first location is angularly aligned with the third location is at least 25 percent greater than the second torque capacity when the second location is angularly aligned with the third location.

15. 14. The motor or generator of claim 13, wherein the rotor and the stator are configured such that the first torque capacity when the first location is angularly aligned with the third location is at least twice the second torque capacity when the second location is angularly aligned with the third location.

16. When viewed along a direction parallel to the axis of rotation, a cross section of the rotor has a circular shape having a first semicircular portion and a second semicircular portion; 6. The motor or generator of claim 1, wherein the rotor comprises a plurality of magnets constructed and arranged to generate the rotor magnetic flux, the plurality of magnets being arranged such that the first semicircular portion of the rotor generates a first portion of the rotor magnetic flux and the second semicircular portion of the rotor generates a second portion of the rotor magnetic flux that is substantially greater than the first portion.

17. When viewed along a direction parallel to the axis of rotation, a cross section of the rotor has a circular shape having a first semicircular portion and a second semicircular portion; 6. A motor or generator as claimed in any preceding claim, wherein the one or more portions of the rotor are configured to generate peak magnetic flux density in a first direction parallel to the axis of rotation at one or more first angular locations of the first semicircular portion of the rotor and at zero or more second angular locations of the second semicircular portion of the rotor, the amount of the one or more first angular locations being greater than the amount of the zero or more second angular locations.

18. When viewed along the direction parallel to the axis of rotation, a cross section of the stator has a circular shape having a first semicircular portion and a second semicircular portion; 18. The motor or generator of claim 17, wherein one or more portions of the stator are configured to generate peak magnetic flux density in a second direction parallel to the axis of rotation at one or more third angular locations of the first semicircular portion of the stator and at zero or more fourth angular locations of the second semicircular portion of the stator, an amount of the one or more third angular locations being greater than an amount of the zero or more fourth angular locations.

19. When viewed along a direction parallel to the axis of rotation, a cross section of the rotor has a circular shape having a first semicircular portion and a second semicircular portion; the first semicircular portion of the rotor includes a first quantity of magnets oriented to generate a respective first portion of the rotor magnetic flux in a first direction parallel to the axis of rotation; the second semicircular portion of the rotor includes a second quantity of magnets oriented to generate a respective second portion of the rotor magnetic flux in the first direction; A motor or generator as claimed in any preceding claim, wherein the first amount is greater than the second amount.

20. When viewed along the direction parallel to the axis of rotation, a cross section of the stator has a circular shape having a first semicircular portion and a second semicircular portion; the first semicircular portion of the stator includes a third quantity of windings oriented to generate a respective first portion of the stator magnetic flux in a second direction parallel to the axis of rotation when energized with a current of a first polarity; the second semicircular portion of the stator includes a fourth quantity of windings oriented to generate a respective second portion of the stator magnetic flux in the second direction when energized with a current of the first polarity; 20. A motor or generator as claimed in claim 19, wherein the third amount is greater than the fourth amount.

21. the rotor comprises one or more magnets configured to generate the rotor magnetic flux, the one or more magnets being circumferentially distributed about the axis of rotation such that the one or more magnets are non-uniformly distributed as a function of angle about the axis of rotation; 6. A motor or generator as claimed in any preceding claim, wherein the stator comprises one or more windings which, upon application of current, generate the stator magnetic flux, the one or more windings being circumferentially distributed around the axis of rotation such that the one or more windings are non-uniformly distributed as a function of angle around the axis of rotation.

22. 1. A method, comprising: Arranging one or more magnets of a rotor of an axial flux motor or generator to generate a rotor flux having a profile that varies circumferentially about an axis of rotation of the rotor, the one or more magnets being constructed and arranged to generate the rotor flux such that one or more locations at which the rotor flux has peak values ​​are distributed non-uniformly about the axis of rotation and in the circumferential direction; arranging one or more flux generating windings of a stator of the axial flux motor or generator to generate a stator flux having a profile that varies in the circumferential direction about the axis of rotation, the one or more flux generating windings constructed and arranged to generate the stator flux such that one or more locations at which the stator flux has peak values ​​are distributed non-uniformly about the axis of rotation and in the circumferential direction; A method comprising:

23. 23. The method of claim 22, wherein arranging the one or more flux generating windings includes arranging one or more printed circuit board segments including the one or more flux generating windings about the axis of rotation such that the one or more printed circuit board segments are non-uniformly distributed as a function of angle about the axis of rotation.

24. 24. The method of any of claims 22-23, wherein arranging the one or more flux generating windings comprises positioning the one or more flux generating windings such that as the rotor rotates through a range of angles relative to the stator at a constant speed, the periodicity of torque generated due to interaction of magnetic fluxes generated by the rotor and stator is irregular.

25. 24. The method of any of claims 22-23, further comprising positioning the one or more magnets and the one or more flux generating windings such that a torque capability provided between the rotor and the stator varies non-periodically as a function of the angular position of the rotor relative to the stator as the rotor rotates through a complete mechanical rotation about the axis of rotation.

26. disposing the one or more magnets includes: orienting at least first, second, and third magnets to generate magnetic flux in a first direction parallel to the axis of rotation; positioning the first and second magnets such that there are no other magnets angularly positioned between the first magnet and the second magnet that are oriented to generate magnetic flux in the first direction; positioning the second and third magnets such that there are no other magnets angularly positioned between the second and third magnets that are oriented to generate magnetic flux in the first direction; positioning the first, second and third magnets such that a first distance between the first magnet and the second magnet is at least twice a second distance between the second magnet and the third magnet; The method according to any one of claims 22 to 23, comprising:

27. Arranging the one or more flux generating windings comprises: orienting at least first, second, and third flux generating windings to generate magnetic flux in a second direction parallel to the axis of rotation; positioning the first and second flux generating windings such that there are no other flux generating windings oriented to generate magnetic flux in the second direction that are angularly positioned between the first and second flux generating windings; positioning the second and third flux generating windings such that there are no other flux generating windings oriented to generate magnetic flux in the second direction that are angularly positioned between the second flux generating winding and the third flux generating winding; positioning the first, second and third flux generating windings such that a third distance between the first flux generating winding and the second flux generating winding is at least twice a fourth distance between the second flux generating winding and the third flux generating winding; 27. The method of claim 26, comprising:

28. positioning the one or more magnets includes positioning a first magnet to generate a first peak magnetic flux density parallel to the axis of rotation at a first location relative to the rotor, and positioning a second magnet to generate a second peak magnetic flux density parallel to the axis of rotation at a second location relative to the rotor; positioning the one or more flux generating windings includes positioning a first flux generating winding to generate a third peak magnetic flux density parallel to the axis of rotation at a third location relative to the stator; 24. The method of any of claims 22-23, wherein the one or more magnets and the one or more flux generating windings are arranged such that a first torque capability between the rotor and the stator when the first location is angularly aligned with the third location is greater than a second torque capability between the rotor and the stator when the second location is angularly aligned with the third location.

29. 30. The method of claim 28, wherein the one or more magnets and the one or more flux generating windings are arranged such that the first torque capacity when the first location is angularly aligned with the third location is at least 25 percent greater than the second torque capacity when the second location is angularly aligned with the third location.

30. 30. The method of claim 28, wherein the one or more magnets and the one or more flux generating windings are arranged such that the first torque capacity when the first location is angularly aligned with the third location is at least twice the second torque capacity when the second location is angularly aligned with the third location.

31. positioning the one or more flux generating windings includes positioning a first flux generating winding at a first location relative to the stator to generate a first peak flux density parallel to the axis of rotation, and positioning a second flux generating winding at a second location relative to the stator to generate a second peak flux density parallel to the axis of rotation; positioning the one or more magnets includes positioning a first magnet to generate a third peak magnetic flux density parallel to the axis of rotation at a third location relative to the rotor; 24. The method of any of claims 22-23, wherein the rotor and the stator are configured such that a first torque capacity between the rotor and the stator when the first location is angularly aligned with the third location is greater than a second torque capacity between the rotor and the stator when the second location is angularly aligned with the third location.

32. 32. The method of claim 31 , wherein the one or more magnets and the one or more flux generating windings are arranged such that the first torque capacity when the first location is angularly aligned with the third location is at least 25 percent greater than the second torque capacity when the second location is angularly aligned with the third location.

33. 32. The method of claim 31 , wherein the one or more magnets and the one or more flux generating windings are arranged such that the first torque capacity when the first location is angularly aligned with the third location is at least twice the second torque capacity when the second location is angularly aligned with the third location.

34. When viewed along a direction parallel to the axis of rotation, a cross section of the rotor has a circular shape having a first semicircular portion and a second semicircular portion; 24. The method of any of claims 22-23, wherein positioning the one or more magnets comprises positioning the one or more magnets such that the first semicircular portion of the rotor generates a first amount of magnetic flux in a first direction parallel to the axis of rotation and the second semicircular portion of the rotor generates a second amount of magnetic flux in the first direction, the second amount being substantially greater than the first amount.

35. When viewed along a direction parallel to the axis of rotation, a cross section of the rotor has a circular shape having a first semicircular portion and a second semicircular portion; disposing the one or more magnets includes: orienting one or more first magnets to generate a peak magnetic flux density in a first direction parallel to the axis of rotation; positioning a first quantity of the one or more first magnets at one or more first angular locations on the first semicircular portion of the rotor; positioning a second quantity of the one or more first magnets at zero or more second angular locations on the second semicircular portion of the rotor; Including, The method of any of claims 22 to 23, wherein the second amount is greater than the first amount.

36. When viewed along a direction parallel to the axis of rotation, a cross section of the stator has a circular shape having a first semicircular portion and a second semicircular portion; Arranging the one or more flux generating windings comprises: orienting one or more first flux generating windings to generate a peak magnetic flux density in a first direction parallel to the axis of rotation; positioning a third quantity of the one or more flux generating windings at one or more third angular locations on the first semicircular portion of the stator; positioning a fourth quantity of the one or more flux generating windings at zero or more fourth angular locations on the second semicircular portion of the stator; Including, The method of any of claims 22-23, wherein the third amount is greater than the fourth amount.

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