Electric rotational machine

Abstract

An electric machine includes a rotor configured to rotate on an axis and a stator spaced radially from the rotor. The stator includes a plurality of stator phases arrayed along the axis, each stator phase including a pair of flux rings and a coil extending about the axis and disposed between the pair of flux rings. Each flux ring includes a plurality of teeth. The teeth are configured to route magnetic flux.

Description

[0001] ELECTRIC ROTATIONAL MACHINE

[0002] CROSS-REFERENCE TO RELATED APPLICATION(S)

[0003] This application claims priority to U.S. Provisional Application No. 63 / 566,025 filed March 15, 2024 and entitled “ELECTRIC ROTATIONAL MACHINE,” the disclosures of which is hereby incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] The present disclosure relates generally to electric machines. More specifically, the present disclosure relates to motors and / or generators, such as transverse flux motors and / or generators.

[0006] Electric motors utilize electricity to generate a mechanical output. Some electric motors generate rotational outputs. In alternating current (A / C) induction motors, a stator is electrically energized to electromagnetically drive rotation of a rotor about a rotational axis. The stator includes laminates and windings. The rotor includes permanent magnets that are acted on by the electromagnetic field induced by current through the stator to cause rotation of the rotor. Such electric motors include coils that extend axially relative to the rotational axis and that extend axially beyond the ends of the rotor to wrap around and form the ends of the coil windings.

[0007] SUMMARY

[0008] According to an aspect of the disclosure, an electric rotational machine includes a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases. Each stator phase includes at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth.

[0009] According to an additional or alternative aspect of the disclosure, an electric rotational machine includes a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases, the controller is a three-phase controller configured to provide a first electrical signal, a second electrical signal, and a third electrical signal. The first electrical signal is provided to a first stator phase of the plurality of stator phases, the second electrical signal is provided to a second stator phase of the plurality of stator phases, and the third electrical signal is not provided to any stator phase of the plurality of stator phases. Each stator phase includes at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth.

[0010] According to another additional or alternative aspect of the disclosure, an electric rotational machine includes a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases. Each stator phase includes at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth. The plurality of stator phases includes a first common phase set having at least two first stator phases and a second common phase set having at least two second stator phases. The at least two first stator phases are wired in parallel. The at least two second stator phases are wired in parallel.

[0011] According to yet another additional or alternative aspect of the disclosure, an electric rotational machine includes a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases. Each stator phase includes at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth. The plurality of stator phases includes a first common phase set having at least two first stator phases and a second common phase set having at least two second stator phases. The at least two first stator phases are wired in series. The at least two second stator phases are wired in series.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a block diagram of an electric machine.

[0014] FIG. 2 is a block diagram of an electric machine.

[0015] FIG. 3 is an isometric view of a fan system.

[0016] FIG. 4A is an isometric view of an electric machine with a housing removed.

[0017] FIG. 4B is a partially exploded isometric view of the electric machine shown in FIG. 4A.

[0018] FIGS. 5A and 5B are isometric cross-sectional views of a portion of a stator phase that demonstrate how flux circuits are formed through flux paired teeth of a stator phase.

[0019] FIG. 5C shows a detailed view of flux paired teeth of a stator phase interacting with concentrators and permanent magnets of a magnet phase of a rotor.

[0020] FIG. 6 is a schematic illustration of a stator of an electric machine.

[0021] FIG. 7 is a schematic illustration of a stator of an electric machine.

[0022] FIG. 8 is a partial, simplified plan view of a stator phase of a stator of an electric machine.

[0023] FIG. 9A is a simplified schematic illustration of a portion of a stator of an electric machine.

[0024] FIG. 9B is a chart illustrating signals provided through respective coils of a stator of an electric machine.

[0025] FIG. 10 is a simplified schematic illustration showing a wiring configuration for a six-phase electric machine.

[0026] FIG. 11 is a simplified schematic illustration showing a wiring configuration for a six-phase electric machine.

[0027] FIG. 12 is a simplified schematic illustration showing a wiring configuration for a six-phase electric machine.

[0028] FIG. 13A is a simplified schematic illustration showing a wiring configuration for a two-phase electric machine.

[0029] FIG. 13B is a chart illustrating signal provided through respective phases of an electric machine. FIG. 14 is a simplified schematic illustration showing a wiring configuration for a four-phase electric machine.

[0030] FIG. 15 is a simplified schematic illustration showing a wiring configuration for a four-phase electric machine.

[0031] FIG. 16 is a schematic illustration of a 3-phase controller.

[0032] FIG. 17 is a schematic illustration of a 2-phase controller.

[0033] DETAILED DESCRIPTION

[0034] The present disclosure concerns electric rotational machines. Such electric rotational machines include motors and / or generators. While a motor will generally be referenced herein as the main example, any or all aspects referenced and / or shown herein can be implemented in a hybrid motor-generator or simply a generator.

[0035] The main type of electric machine presented herein is a transverse flux machine, which is distinguished from axial or radial flux type electric motors. However, the inventive aspects discussed herein can be applied to various types of electric machines beyond just transverse flux machines.

[0036] The electric machines of this disclosure include a rotor rotatable about a rotational axis and a stator. The stator extends about the axis of rotation and can be around or within the rotor. The stator can be configured to electromagnetically drive rotation of the rotor.

[0037] According to aspects of the disclosure, the stator of the transverse flux electric motor includes stator phases, such as one, two, three, or more, formed from flux rings and a coil disposed axially between opposing flux rings. The flux rings include teeth that extend radially relative to the rotational axis and towards the rotor.

[0038] Flux rings according to the disclosure can be formed by multiple ring segments that each extend partially about the rotational axis. The ring segments define the flux ring but may not be in direct contact with each other. The ring segments can instead be fixed together by potting compound. In some examples, adjacent ones of the ring segments are not connected together by laminate structure. Instead, the potting compound is the only structure that bridges the circumferential gaps between the adjacent ring segments. A flux ring can include at least one circumferential gap such that the flux ring may not include a single ring of laminate structure in contact fully about the rotational axis (whether monolithic or formed by contacting ring segments).

[0039] The opposing flux rings of a single stator phase can be joined by axial returns contacting each flux ring and disposed on an opposite radial side of the coil from the rotor. The axial returns can form the radial-most portion of the laminate structures of the phases (e.g., radially inward for an outer rotating machine and radially outward for an inner rotating machine) . The axial returns can be fixed by the potting compound.

[0040] The potting compound can be formed by epoxy and can extend from radially beyond the teeth to the stator housing in a continuous matrix.

[0041] The rotor includes permanent magnets and can include concentrators interspersed between the permanent magnets. The interspersed concentrators and permanent magnets form a magnet array of the rotor. The permanent magnet array formed by the interspersed permanent magnets and concentrators can be formed in axially-arrayed magnet phases.

[0042] According to aspects of the disclosure, an electric rotational machine can include common phase sets. A common phase set can include one or more than one stator phase. The stator phases within a common phase set are wired together and configured to receive a common driving signal. According to some aspects of the disclosure, the common phase sets can be wired in parallel. According to some aspects of the disclosure, the common phase sets can be wired in series.

[0043] Electric rotational machines according to aspects of the disclosure can include three, or a multiple of three, common phase sets. Such an electric machine can be operatively connected to a three-phase controller that controls provision of electric signals to the stator phases.

[0044] Electric rotational machines according to aspects of the disclosure can include two, or a multiple or two, common phase sets. Such an electric machine can be operatively connected to a three-phase controller that controls provision of electric signals to the stator phases. The three-phase controller can be configured to provide a non-driving signal that bypasses coils of the stator and is routed to a common terminal. According to various aspects of the disclosure, the non-driving signal can be different from the driving signals. The non-driving signal can have a different amplitude from the driving signals. The nondriving signal can be offset from the driving signals by a different degree than the driving signals are offset from each other.

[0045] Several of the figures of the disclosure show a common axis, which is sometimes referred to as a rotational axis. An axis of rotation of the rotor is disposed coaxially with the common axis. The term annular is used herein, which can refer to a ring shape (continuous or broken) about the common axis, which can be coaxial with the common axis. The term radial is used herein which when referring to a direction is any direction orthogonal to the common axis, unless otherwise noted. The term axial is used herein which when referring to a direction is any direction parallel with the common axis, unless otherwise noted. The terms circumferential or circumferentially as used herein means around the common axis, unless otherwise noted.

[0046] Components can be considered to radially overlap when those components are disposed at common axial locations along an axis. A radial line extending from the axis will extend through each of the radially overlapping components. Components can be considered to axially overlap when those components are disposed at common radial and circumferential locations relative to an axis such that an axial line parallel to the axis extends through the axially overlapping components. Components can be considered to circumferentially overlap when aligned about the axis, such that a circle centered on the axis passes through the circumferentially overlapping components.

[0047] FIG. 1 is a block diagram of electric machine 10. FIG. 2 is a block diagram of electric machine 10. FIG. 1 shows electric machine 10 in an outer rotator configuration in which the rotor 12 is spaced radially outward from the stator 14. FIG. 2 shows electric machine 10 in an inner rotator configuration in which the rotor 12 is spaced radially inward from the stator 14. FIGS. 1 and 2 are discussed together. Electric machine 10 includes rotor 12, stator 14, and motor controller 16. Rotor 12 includes rotor body 18 and permanent magnet array 20. Stator 14 includes stator phases 22a, 22b, 22c (collectively herein “stator phase 22” or “stator phases 22”). While stator 14 is shown as a three-phase stator in the example shown, it is understood that stator 14 can be of any desired configuration regarding phase count, such as two, three, four, six, or more phases. Stator phase 22a includes flux rings 24a, 24b, coil 26, and axial returns 28. Stator phase 22b includes flux rings 24c, 24d, coil 26, and axial returns 28. Stator phase 22c includes flux rings 24e, 24f, coil 26, and axial returns 28. Flux rings 24a-24f are referred to collectively herein as “flux rings 24” or “flux ring 24.” Each flux ring 24 can be considered to form a half phase of a stator phase 22.

[0048] Rotor 12 is spaced radially from stator 14 such that air gap 30 is formed between rotor 12 and stator 14. Electric machine 10 extends along axis CA and rotor 12 is configured to rotate on axis CA. Axis CA can be considered to be an axis of rotation of the rotor 12.

[0049] In the example shown in FIG. 1, rotor 12 surrounds stator 14 such that electric machine 10 is an outer rotator. In the example shown in FIG. 2, electric machine 10 includes stator 14 extending about rotor 12 such that electric machine 10 is an inner rotator. Permanent magnet array 20 is supported by the rotor body 18. Permanent magnet array 20 is disposed across air gap 30 from stator 14 such that permanent magnet array 20 is spaced radially from stator 14. Permanent magnet array 20 includes a plurality of permanent magnets disposed annularly about motor axis MA. Permanent magnet array 20 can further include a plurality of concentrators, as discussed in more detail below. It is understood that in various examples the rotor body 18 can be formed by flux directing material of the rotor 12 (e.g., by laminas forming the concentrators among other options). In various other examples, the rotor body 18 can be formed separate from such flux directing structure and the permanent magnet array 20 can be mounted on that rotor body 18.

[0050] Stator 14 is formed by stator phases 22 arrayed along the axis CA. Each stator phase 22 includes paired flux rings 24 that are disposed on opposite axial sides of a coil 26 of that stator phase 22. The coil 26 is disposed directly axially between the flux rings 24 of the same stator phase 22. Flux rings 24a, 24b are paired to form stator phase 22a and are disposed on opposite axial sides of the coil 26 of stator phase 22a. Flux rings 24c, 24d are paired to form stator phase 22b and are disposed on opposite axial sides of the coil 26 of stator phase 22b. Flux rings 24e, 24f are paired to form stator phase 22c and are disposed on opposite axial sides of the coil 26 of stator phase 22c.

[0051] In some examples, portions of each flux ring 24 can extend axially over the coil 26. As such, portions of each flux ring 24 can be disposed directly radially between the coil 26 and rotor 12. Flux rings 24 are formed by laminations and can include powdered metal components, though not all examples are so limited.

[0052] Laminations can be formed from material which is readily susceptible to polarization from the electromagnetic fields generated by coils 26. Such material is typically ferromagnetic. The ferromagnetic materials can be metal such as iron or an alloy of iron, such as steel. More specially, laminations can be formed from silicon steel, among other options. Ferromagnetic material can be a ceramic that is doped or otherwise embedded with ferromagnetic elements. The laminations can be stacked together to form lamination stacks. Laminations can also be referred to as laminas.

[0053] In the example show, each stator phase 22 includes axial returns 28 that are disposed on an opposite radial side of coil 26 from permanent magnet array 20. Axial returns 28 extend between and connect paired ones of the flux rings 24 in each stator phase assembly 22. Axial returns 28 electromagnetically connect the paired flux rings 24. Axial returns 28 can be formed by stacked laminations having an axially oriented lamination grain (e.g., parallel with the motor axis MA). The laminations forming the axial returns 28 can be stacked circumferentially along a width of the axial return and extend axially along a length of the axial return 28. While electric machine 10 is shown as including axial returns 28, it is understood that not every example is so limited. For example, the electric machine 10 can be configured as a double air gap electric machine 10 and may not include axial returns 28.

[0054] Each coil 26 is a winding, typically copper, around the motor axis MA. Thus, each coil 26 could be a continuous winding of multiple loops (e.g., 2, 3, 4, 5, 10, 15, 20, 40, 50, 100, or more) around the motor axis MA. Examples of the winding can be formed by round wire or ribbon strand.

[0055] Controller 16 is operably connected to electric machine 10, electrically or communicatively, to control operation of electric machine 10, thereby controlling the rotational output of electric machine 10. Controller 16 can be of any desired configuration for controlling operation of electric machine 10 and can include control circuitry (e.g., one or more of a processor, a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a graphics processing unit (GPU), a system-on-module (SOM), or other equivalent discrete or integrated logic circuitry) and computer-readable memory.

[0056] Controller 16 is configured to store executable code, implement functionality, and / or process instructions. Controller 16 is configured to perform any of the functions discussed herein, including controlling operation of any components referenced herein. Controller 16 can be of any suitable configuration for controlling operation of electric machine 10, gathering data, processing data, etc. Controller 16 can include hardware, firmware, and / or stored software. Controller 16 can be of any type suitable for operating in accordance with the techniques described herein. While controller 16 is illustrated as a single unit, it is understood that controller 16 can be entirely or partially mounted on one or more circuit boards. In some examples, controller 16 can be implemented as a plurality of discrete circuitry subassemblies.

[0057] During operation, an alternating current (A / C) signal is run through each coil 26. The A / C signal rapidly builds and collapses the magnetic field due to the current reversal of the A / C signal through the coil 26. Flux concentrating material of each stator phase assembly 22 (e.g., the lamina stacks) is wrapped around at least three sides of the coil 26. Generally, magnetic flux flows with the grain, along the direction of lamination, as flux will generally follow the path of highest permeability and there is resistance to flux jumping from one layer of lamination to another layer of lamination. At least a portion of the lamination grain of the flux rings 24 can be radially orientated relative to axis CA while the lamination grain of the axial returns 28 can be axially oriented relative to axis CA. As such, the flux can flow axially through the axial returns 28 and radially through flux rings 24 in a U-shaped path about coil 26 and towards rotor 12.

[0058] The A / C signal routed through the coil 26 is synchronized to develop magnetic fields through the flux rings 24 in time with the rotational position of permanent magnet array 20 to drive rotation of rotor 12. The respective A / C signals (e.g., sinusoidal or trapezoidal) delivered through the coils 26 in each stator phase 22a, 22b, 22c are out of phase with respect to each other. In this way, the magnets of the permanent magnet array 20 more frequently have flux peaks acting on them, as compared to synchronizing the sinusoidal A / C signals, thereby providing a smoother torque profile acting on the rotor 12 along the axis CA.

[0059] The examples of the electric machine 10 discussed in FIGS. 1 and 2 have three stator phases 22 (corresponding to the three stator phases 22a, 22b, 22c) and respective coils 26 therein. As such, three A / C signals are delivered through the coils 26 120-degrees electrically offset. In some examples, pairs of the phases (e.g., three phase pairs in a six phase example) can be provided with electrically aligned signals such that the electric signals are electrically offset between phase pairs but electrically aligned within a phase pair (e.g., three phase pairs for a six phase example).

[0060] FIG. 3 is an isometric view of fan system 32. Fan system 32 includes electric machine 10, which is configured as a motor in this example, and blade assembly 34. Motor housing 36, supports 38, and drive shaft 40 of electric machine 10 are shown. Motor housing 36 includes stator housing 42 and bearing housing 44. Blades 46 and fan hub 48 of blade assembly 34 are shown.

[0061] Electric machine 10 is shown as an electric motor configured to generate a rotating mechanical output. In the example shown, electric machine 10 is configured to generate the output coaxially with common axis CA. Motor housing 36 encloses other components of electric machine 10. In the example shown, motor housing 36 includes a first, larger diameter portion and a second, smaller diameter portion. The first portion is formed by stator housing 42 and the second portion is formed by bearing housing 44. Both stator housing 42 and bearing housing 44 enclose rotating components of electric machine 10. Electric components of electric machine 10 are disposed, at least partially, within stator housing 42. Supports 38 extend axially from stator housing 42 and are configured to interface with a support surface. In some examples, supports 38 can rest on the support surface such that stator housing 42 extends vertically above supports 38. Bearing housing 44 is disposed a lower axial end of stator housing 42 opposite blade assembly 34. Bearing housing 44 can thereby be disposed vertically between stator housing 42 and the support surface. In the example shown, bearing housing 44 has a smaller diameter than stator housing 42 and is located vertically below stator housing 42.

[0062] Blade assembly 34 is connected to electric machine 10 to be rotated by electric machine 10. Drive shaft 40 extends from electric machine 10 to provide the rotating mechanical output from electric machine 10 to blade assembly 34 to rotate blades 46 on common axis CA. Fan hub 48 is disposed at an end of drive shaft 40 opposite electric machine 10. More specifically, fan hub 48 is disposed at a distal end of drive shaft 40 opposite a second distal end of drive shaft 40 extending into bearing housing 44. Blades 46 extend radially outward from fan hub 48. In the example shown, electric machine 10 and blade assembly 34 are disposed coaxially on common axis CA such that blades 46, fan hub 48, drive shaft 40, and the rotor of electric machine 10 rotate coaxially.

[0063] In the example shown, fan system 32 is configured such that blade assembly 34 is disposed vertically above stator 14 and rotor 12. For example, fan system 32 can be configured for use in a cooling tower. It is understood that, while vertically oriented fans are discussed, fans according to the present disclosure can be oriented in any desired orientation and can be used to move any desired fluid, including gas and / or liquid. Further, while electric machine 10 is described as driving blade assembly 34, it is understood that any one or more aspects of electric machine 10 can be implemented in non-fan applications. Electric machine 10 can be configured for use in any desired electric motor assembly. It is thus understood that, while a fan is one implementation of the motor technologies presented herein, other applications, including non-fan applications, are possible and contemplated as within the scope of the disclosure.

[0064] FIG. 4A is an isometric view of electric machine 10 with the housing removed. FIG. 4B is a partially exploded isometric view of the electric machine 10 shown in FIG. 4A. FIGS. 4A and 4B will be discussed together. Drive shaft 40, rotor 12, and stator 14 of electric machine 10 are shown. Stator 14 is formed in stator phases 22a-22c. Stator phase 22a includes flux rings 24a, 24b, coil 26, and axial returns 28. Stator phase 22b includes flux rings 24c, 24d, coil 26, and axial returns 28. Stator phase 22c includes flux rings 24e, 24f, coil 26, and axial returns 28. Rotor 12 includes rotor body 18 and permanent magnet array 20. Rotor 12 is formed in rotor phases 50a-52c in this example, though it is understood that not all examples are so limited. Rotor phase 50a includes rotor hub 52 and magnet phase 54a. Rotor phase 50b includes rotor hub 52 and magnet phase 54b. Rotor phase 50c includes rotor hub 52 and magnet phase 54c.

[0065] Stator 14 and rotor 12 are disposed coaxially in this example to generate a rotational mechanical output based on electrical inputs. In the example shown, rotor 12 is disposed within stator 14 such that electric machine 10 is an inner rotator, though it is understood that other examples of electric machine 10 are configured as outer rotators having a rotor disposed about the stator. Stator 14 defines a cylindrical interior that rotor 12 is disposed within. Stator 14 is formed by stator phases 22 arrayed along common axis CA. Each stator phase 22 is an annular ring disposed about common axis CA.

[0066] The stator phases 22a-22c do not overlap each other along common axis C A. Stator phases 22a-22c do not radially overlap along axis CA, such that a radial line extending from common axis CA passes through at most only one of the stator phases 22 and does not pass through multiple ones of the stator phases 22 at any given location along common axis CA. The electromagnetic components of each stator phase 22 (e.g., lamina structure and coils 26) only radially overlap with components of that same stator phase 22 and do not radially overlap with electromagnetic components of another of the stator phases 22. For example, axial returns 28 of stator phase 22a only support the function of stator phase 22a and not, for example, stator phase 22b or stator phase 22c. The flux rings 24a, 24b of stator phase 22a only support the function of stator phase 22a and not, for example, stator phases 22b, 22c. Each of the stator phases 22a-22c may only contain one coil 26 and two annular flux rings 24 and, in some cases, only two annular laminate pieces forming the flux rings 24.

[0067] Each stator phase 22 includes first and second flux rings 24 (e.g., flux rings 24a, 24b of stator phase 22a) disposed on opposite lateral sides of a coil 26 of that stator phase 22. In some examples, each flux ring 24 is formed by multiple ring segments 56 fixed relative to each other and extending about the common axis CA. In some examples, the flux ring 24 can be formed by a single laminate structure that extends about the axis CA, such that the flux ring 24 does not include multiple ring segments 56.

[0068] Ring segments 56 are each arcuate portions of laminate structure that together form the annular laminate structure of flux ring 24. Teeth 58 are formed on a radial side of each ring segment 56 facing rotor 12. For example, teeth 58 can project radially inward in examples in which electric machine 10 is an inner rotator and teeth 58 can project radially outward in examples in which electric machine 10 is an outer rotator.

[0069] An annular array of axial returns 28 extends between connects the opposing flux rings 24. The axial returns 28 are disposed on an opposite radial side of the flux rings 24 from rotor 12 and teeth 58. As shown, the axial returns 28 form the outermost electrically conducting portion of stator 14. In the example shown, axial returns 28 form the outermost laminate structure of the electric machine 10 as electric machine 10 is shown as an inner rotator. It is understood that in examples in which electric machine 10 is an outer rotator the axial returns 28 can form the innermost laminate structure of the electric machine 10. The axial returns 28 extend radially outward from the common axis CA further than the flux rings 24 or other laminate or metal superstructure. In the example shown, stator 14 does not include any laminate or metallic superstructure. Stator 14 does not include a support structure on the side of the axial returns 28 opposite rotor 12. In the example shown, stator 14 does not include a support structure on the outer radial side of axial returns 28. It is understood, however, that not all examples are so limited.

[0070] Axial returns 28 can be connected directly to stator housing 42, such as by potting compound, and interface with other laminate portions of stator 14 on only the inner radial side of the axial return 28 and, in some cases, interface with the other laminate portions on one or both circumferential sides of the axial return 28. Axial returns 28 are not disposed radially between laminate structures of stator 14 in this example. Axial returns 28 are not disposed radially between laminate structure that is itself directly connected to teeth 58 by laminate or other electrically conductive structure in this example. It is understood, however, that not all examples are so limited.

[0071] For each stator phase 22, coil 26 is disposed axially between the first and second flux rings 24 of the stator phase 22. Wire ends 68 extend from coil 26 at a location radially between the axial returns 28 and rotor 12 to a location radially outside of the axial returns 28 through wire gaps. Wire ends 68 are thereby exposed outside of electric machine 10 and provide locations for electrical connections to be formed with electric machine 10. The wires ends 68 of the multiple coils 26 of the stator phases 22a-22c are shown as arrayed along the common axis CA and aligned axially along the common axis CA.

[0072] Rotor 12 is configured similar to stator 14, in the example shown, in that rotor 12 is formed from multiple rotor phases 50 configured to operate together. It is understood, however, that not all examples are so limited. For example, the rotor 12 can include a single magnet array 20 that extends the length of the rotor 12 such that each stator phase 22 interacts with the same magnet array 20 of the rotor 12.

[0073] Rotor body 18 supports permanent magnet array 20. As best seen in FIG. 4B, the rotor 12 includes three rotor phases 50a-50c. Each rotor phase 50 corresponds with a single stator phase 22 of stator 14. It is understood that electric machine 10 can include more or fewer than three rotor phases 50. For example, electric machine 10 can include a single rotor phase 50 that magnetically interacts with each of the multiple stator phases 22 of the stator 14. It is understood that in various other examples the electric machine 10 can include a single permanent magnet array 20 that radially overlaps with all of the stator phases 22 of the stator 14.

[0074] Permanent magnet array 20 is formed by interposed permanent magnets 60 and concentrators 62. Concentrators 62 can be formed by stacks of laminas. For example, concentrators 62 can be formed by lamina sheets that are stacked axially, among other options. In the example shown, permanent magnet array 20 is formed by magnet phases 54a-54c respectively associated with rotor phases 50a-50c.

[0075] Rotor 12 is mounted on drive shaft 40. In the example shown, each rotor phase 50 includes a rotor hub 52 connected to the drive shaft 40 and forming a portion of the rotor body 18. In the example shown, each magnet phase 54 is disposed on the outer radial side of an associated rotor hub 52.

[0076] Each stator phase 22 includes two annular arrays of teeth 58 disposed on opposite axial sides of the coil 26 of that stator phase 22. It is understood that in some examples the teeth 58 do not extend to radially overlap with the coil 26 while in various other examples the teeth 58 can include portions that extend at least partially axially to radially overlap with the coil 26.

[0077] Each stator phase 22 includes a first flux ring 24 and a second flux ring 24. The first flux ring 24 (e.g., flux ring 24a of stator phase 22a; flux ring 24c of stator phase 22b; and flux ring 24e of stator phase 22c) and its associated components and aspects can be referred to as forming an A-side of the stator phase 22. The second flux ring 24 (e.g., flux ring 24b of stator phase 22a; flux ring 24d of stator phase 22b; and flux ring 24f of stator phase 22c) and its associated components and aspects can be referred to as forming a B-side of the stator phase 22. The first flux ring 24 has a first annular array of teeth 58 and the second flux ring 24 has a second annular array of teeth 58.

[0078] Within each stator phase 22, the first annular array of teeth 58 is disposed on a first axial side of coil 26 (e.g., spaced in first axial direction ADI from its coil 26) while the second annular array of teeth 58 is disposed on the second, opposite axial side of the coil 26 (e.g., spaced in second axial direction AD2 from its coil 26). Within each stator phase 22, the teeth 58 of the first annular array of teeth 58 are at least partially misaligned or offset (circumferentially and axially) relative to the teeth 58 of the second annular array of teeth 58 (e.g., teeth 58 of flux ring 24a are axially misaligned with teeth 58 of flux ring 24b). This misalignment of the A-side teeth 58 relative to the B-side teeth 58 facilitates flux coupling across the magnet array 20 from oppositely poled teeth 58 of the respective A- side and B-side annular arrays of teeth 58.

[0079] While the teeth 58 within each stator phase 22 are offset and misaligned (circumferentially and axially), the respective A-side teeth 58 of the multiple stator phases 22 can be axially aligned and the respective B-side teeth 58 of the multiple stator phases 22 can be axially aligned. It is understood, however, that not all examples are so limited. For example, the respective A-side teeth 58 of the multiple stator phases 22 can be axially misaligned relative to each other. For example, the respective A-side teeth 58 of the multiple stator phases 22 in a three phase electric machine 10 can be circumferentially offset and axially misaligned to facilitate driving signals 120-degrees electrically offset through each of the three stator phases 22. The driving signals can be between about 110- degrees and 130-degrees offset in some examples.

[0080] The A / C signals routed through the coils 26 are synchronized to develop magnetic fields through the flux rings 24 in time with the rotational position of permanent magnet array 20 to drive rotation of rotor 12. The respective A / C signals (e.g., sinusoidal or trapezoidal) delivered through the coils 26 in each stator phase 22a-22c are out of phase with respect to each other. In this way, the permanent magnets 60 forming the permanent magnet array 20 more frequently have flux peaks acting on them, as compared to synchronizing the sinusoidal A / C signals, thereby providing a smoother torque profile acting on the rotor 12 along the axis of rotation of rotor 12.

[0081] The embodiment of the electric machine 10 discussed has three phases corresponding to the three stator phases 22a, 22b, 22c and respective coils 26 therein. As such, three sinusoidal A / C signals are delivered through the coils 26 120-degrees electrically offset. If there were two stator phases 22 and two coils 26, then the two sinusoidal A / C signals would be 180-degrees electrically offset, or 90-degrees electrically offset for sets of four stator phases 22 and four coils 26. Stator phases 22a-22c can each be of the same configuration such that a common base stator phase 22 can be used to form any one of the multiple stator phases 22 of the electric machine 10.

[0082] Two opposite polarized states are shown between FIGS 5A and 5B. As shown, the alternating flux path directions and polarizations are developed through the laminate of the ring segments 56 and axial returns 28. The alternating flux paths can be due to a sinusoidal signal delivered to each coil 26 to flux pair adjacent teeth 58 on opposite sides of the coil 26. These flux paths polarize the teeth 58a relative to teeth 58b to attract or repel the permanent magnets 60 of rotor 12 in synchrony with rotation of the rotor 12 so that flux paired ones of the teeth 58 attract a permanent magnet 60 as the permanent magnet 60 approaches and / or repel the permanent magnet 60 as the permanent magnet 60 passes.

[0083] Flux paired teeth 58 refer to respective closest pairs of teeth 58 of opposed circular tooth arrays of a stator phase 22 (e.g., the teeth 58 of flux ring 24a and teeth 58 of flux ring 24b are flux paired, the teeth 58 of flux rings 24c, 24d are flux paired, the teeth 58 of flux rings 24e, 24f are flux paired). While a subset of teeth 58a, 58b are highlighted as flux paired ones of teeth in FIGS. 5A and 5B, it is understood that these are examples and all teeth 58a, 58b of flux rings 24a, 24b similarly flux pair across the circular arrays of teeth 58a, 58b.

[0084] Each tooth 58a is part of a similar flux circuit with its corresponding flux pair tooth 58b. The flux paired teeth 58a, 58b pair generally axially with a tooth 58a, 58b of the opposing circular array of teeth 58a, 58b, and not circumferentially to the neighbor tooth 58a, 58b of the same circular array of teeth 58a, 58b because all teeth 58a of the circular array of teeth 58a will have the same polarity at any given time while all teeth 58b of the opposed circular arrays of teeth 58b of the same stator phase 22a will have the opposite polarity at any given time. More specifically, each tooth 58a of the circular array of teeth 58a flux pairs with the closest teeth 58b of the circular array of teeth 58b on the other axial side of the coil 26. As shown in FIGS. 5A and 5B, a flux circuit is formed through flux paired teeth 58a, 58b such that the teeth 58a, 58b are respectively polarized, north and south.

[0085] In various examples, each tooth 58 can narrow circumferentially as the tooth 58 extends radially away from the body of its flux ring 24. The lamina structure that the tooth 58 extends from, which can form the body of the flux ring 24 or of a ring segment 56, forms a lamina base 64 from which the teeth 58 extend. Multiple adjacent teeth 58 of an annular array of teeth 58 can extend from a common lamina base 64. In some examples, all teeth 58 of an annular array of teeth 58 can extend from a common lamina base 64 such as in examples in which the flux ring 24 does not include multiple ring segments 56. The teeth 58 can be wholly or partially formed by the laminas that form the common lamina base 64. As such, multiple adjacent ones of the teeth 58 can be formed from the same laminas and monolithic with each other.

[0086] In the example shown, teeth 58 extend to a tooth face 66 oriented towards rotor 12. In the example shown, the teeth 58 each narrow to the tooth face 66, though it is understood that not all examples are so limited. The tooth faces 66 can be planar and / or can be formed tangentially to a circle centered on common axis CA, among other options. The tooth faces 66 provide a narrowed surface area relative to the lamina base 64 and the axial returns 28. Teeth 58 narrow to concentrate flux towards rotor 12 to focus concentrated flux to a limited part of the rotor 12.

[0087] The magnetic flux is generated by coil 26. Specifically, an A / C signal is run through coil 26 which rapidly builds and collapses the magnetic field due to the current reversal of the A / C signal through the coil 26. As shown, flux concentrating material of a stator phase 22 is wrapped around at least three sides of the coil 26. In the example shown, the flux rings 24a, 24b and axial returns 28 wrap around at least three sides of the coil 26. The lamination grain of the flux concentrating material is shown in FIGS. 5A-5C. The lamination grain of the concentrators 160 and axial returns 48 can further be seen in FIG. 5C. While the concentrators are shown as including circumferentially stacked lamina sheets that extend axially, it is understood that not all examples are so limited. For example, the lamina sheets forming a concentrator 62 can be stacked axially.

[0088] Generally, flux flows with the grain, along the direction of lamination, as flux will generally follow the path of highest permeability and there is significant resistance to flux jumping from one layer of lamination to another layer of lamination. The lamination grain of the ring segments 56, including the teeth 58a, 58b, is radially orientated while the lamination grain of the axial returns 28 is axially oriented. As such, the flux flows axially through the axial returns 28 and radially through the ring segments 56 and teeth 58a, 58b in a U shape toward the rotor 12, with the base of the U on an opposite side of the coil 26 from the rotor 12 and the legs of the U oriented towards the rotor 12. FIGS. 5A and 5B represent the reversal of the A / C signal and how the poles of the flux paired teeth 58a, 58b are switched.

[0089] The flux paired ones of teeth 58a, 58b are circumferentially offset from each other such that the teeth 58a of one flux ring 24 are not axially aligned with teeth 58b of the other flux ring 24 of the same stator phase 22. Being that the ends of the flux paired teeth 58a, 58b of the same stator phase 22 are not aligned axially, because teeth 58a are offset circumferentially from teeth 58b, the flux circuit travels at least a limited distance circumferentially between the flux paired ones of teeth 58a, 58b. Therefore, a cumulative flux circuit comprised of a plurality of flux paired teeth 58a, 58b can flow in a spiral pattern circumferentially through the teeth 58a, 58b and axial returns 28. It is noted that, while most flux flows between flux paired ones of teeth 58a, 58b, the ring segments 56 permit flux flow between teeth 58a, 58b of the same ring segment 56, such that a limited amount of flux may skip a set of flux paired teeth 58a, 58b to the next-over tooth 58a, 58b of the same ring segment 56. As discussed above, adjacent ring segments 56 of the same flux ring 24 can be separated by one or more circumferential gaps that is bridged only by potting compound. The adjacent ring segments 56 are isolated to prevent flux flow between the adj cent ring segments 56, thereby inhibiting the formation of eddy currents and facilitating efficient operation of electric machine 10.

[0090] While the illustrated electric machine embodiment generally shows aligned teeth across the stator phases and offset magnet phases of the rotor, this convention can be reversed such that the teeth are offset between phases and the magnets are aligned across phases, among other options.

[0091] FIG. 5C shows a detailed view of flux paired teeth 58a, 58b of the stator 14 interacting with concentrators 62 and permanent magnets 60 of the magnet array 20. The A / C signal through the coil 26 changes the direction of the electric current rapidly and thus changes the north-south polarity of the flux paired teeth 58a, 58b rapidly. The view of FIG. 5C shows an instance in which all teeth 58a of the circular array of teeth 58a have a north polarization while all teeth 58b of the circular array of teeth 58b have a south polarization.

[0092] Also at this instance, the teeth 58a, 58b are aligned with the concentrators 62 that are disposed circumferentially between the permanent magnets 60. The laminate of the concentrators 62 does not have an inherent polarization, but due to the fixed position of concentrators 62 between magnet poles, the concentrators 62 assume an effective permanent polarization as indicated. Each concentrator 62 contacts two permanent magnets 60. Each concentrator 62 contacts the same pole of the two permanent magnets 60. For example, a concentrator 62 will be in contact with two south poles or be in contact with two north poles. The concentrators 62 take on alternating north and south polarization on opposite sides of each permanent magnet 60 depending on the polarization adjacent that concentrator 62. As indicated, each permanent magnet 60 is permanently polarized north and south on opposite sides of its short axis. The interleaved arrangement of permanent magnets 60 and concentrators 62 creates circumferential regions of oppositely polarized concentrators 62 and permanent magnet 60 poles.

[0093] The concentrators 62 route the magnetic flux from the permanent magnets 60 toward the stator 14. Flux circuits are completed across the air gap 30 between the stator 14 and rotor 12. The flux from the rotor 12 (specifically the permanent magnets 60) and the flux from the coil 26 (through the teeth 58a, 58b) interact in the air gap 30, and the resulting flux shear forces rotation of the rotor 12. The flux of the present electric machine 10 has an orientation transverse to the axis of rotation (which axis of rotation is coaxial with common axis CA). This is different from the radial flux orientation of traditional A / C and D / C brushless motors.

[0094] The flux generated by the stator 14 and acting on the rotor 12 is constantly changing due to both changing position of the permanent magnets 60 and concentrators 62 due to rotation of the rotor 12 as well as the change in polarization of the teeth 58a, 58b due to the change in the A / C signal through the coil 26. As such, the A / C signal routed through the coil 26 is synchronized with rotation of the rotor 12 to develop magnetic fields through the teeth 58a, 58b in time to the concentrators 62 approaching and departing the teeth 58a, 58b to simultaneously push and pull the permanent magnets 60 of the rotor 12 to provide the force that rotates the rotor 12. More specifically, the N-N and S-S interfaces repel while N- S interfaces attract, on approach and departure of alignment.

[0095] At least some of the respective A / C signals (e.g., sinusoidal or trapezoidal) delivered through the multiple coils 26 forming stator 14 are out of phase with respect to each other. In this way, the rotor 12 (along its axial length) more frequently has flux peaks acting on it, as compared to synchronizing the sinusoidal A / C signals, for a smoother torque profile acting on the rotor 12 along the axis of rotation of the rotor 12, which is also the common axis CA.

[0096] Traditional A / C induction motors use a plurality of discrete coils that form an array of coils that extend circumferentially around the axis of rotation of the rotor. Each coil represents a potential pole for acting on a magnet. The discrete coils arrayed circumferentially around the axis of rotation in a conventional A / C induction motor are out of phase with respect to each other. The discrete coils can interact with a small subset of the magnets at any given instance. The potential torque generated is proportional to the number of poles. The number of poles in such a motor is limited by the ability to fit discrete coils circumferentially around the axis of rotation within the motor. Coil windings can be made smaller, and the diameter of the stator can be made bigger, to accommodate more coils to support more poles, but this increases the size, weight, and cost of the motor and still has limits. Power can also be increased when the rotor is rotating at a relatively high rate, whereby more coil-magnet passes can be experienced per unit time. But such power increase requires the motor to operate at relatively high speed when some applications may desire low-speed output. Providing reduction gearing to reduce speed and increase torque to the desired high torque and low speed increases cost, weight, size, and friction.

[0097] Electric machines 10 according to the present disclosure are different from traditional A / C and D / C machines. An aspect of the electric machine 10 is that it contains relatively few coils 26, only three in the illustrated embodiment. Unlike traditional A / C and D / C motors, the coils 26 are formed from loops of wire that extend entirely around the axis of rotation of the rotor 12 (and the common axis CA). The axis of rotation of the rotor 12 (and the common axis CA) extends through each loop (e.g., the center of each loop). Each coil 26 is annular, and the loops of each coil 26 are like wise annular, and the circular planar profile of the coil 26 and loops are orthogonal to the common axis CA. The wire of each coil 26 forms a single hoop, which has multiple loops that overlap and contact one another to form the single hoop assembly. The coils 26 do not include loops that generate flux that rotates the rotor 12 through which the common axis CA does not extend. Instead of adding a coil for each pole as in traditional A / C induction motors, the flux rings 24 and axial returns 28 surrounding a single coil 26 channel the flux to a plurality of teeth 58 that flux pair across the flux rings 24 of a stator phase 22 to create a plurality of poles from the single coil 26.

[0098] In the example shown, for each stator phase 22, one coil 26 supports multiple poles equal to the number of teeth 58 of a single flux ring 24. For example, if each flux ring 24 includes twenty-four teeth 58, then twenty-four poles will be formed from the single coil 26 between those flux rings 24. It is understood that lower and higher poles can be created depending on the number of teeth 58. As such, activating one coil 26 activates many poles, whereas in some traditional A / C and D / C motors activation of one coil activates only one pole. Multiple coils 26 are arrayed along the axis of rotation of the rotor 12 with each coil 26 interacting with the magnet array 20, thereby multiplying the number of poles.

[0099] The high pole count eliminates or reduces the need for reduction gearing for outputs from electric machine 10, reducing off-center forces as well as reducing weight and friction, allowing for a more compact arrangement of electric machine 10. The electric machines 10 of the present disclose can generate high torque with a small package size, even at low speed. Therefore, gear reduction of a drive can be minimized or entirely excluded, providing savings on cost, size, weight, and friction.

[0100] FIG. 6 is a simplified schematic diagram showing a plurality of stator phases 42 of an electric machine 10. In the example shown, the stator 14 is shown as a three-phase stator. The three phases can be similar to those shown. In various examples, the teeth of the flux rings 24 of the respective stator phases 22 are slightly offset from each other, rotationally about the common axis CA, and different drive signals are delivered to the respective coils 26 of the respective stator phases 22. The teeth 58 of the various stator phases 22 can be circumferentially offset such that the teeth 58 of the various phases 22 are not directly axially aligned with each other. Such circumferentially offset teeth 58 can still axially overlap but also include portions that do not axially overlap with each other. Each stator phases 22 includes a pair of flux rings 24 with a coil 26 disposed axially between the paired flux rings 24.

[0101] The offsetting of the teeth 58 and offset driving signals balance the electric machine 10 such that the teeth 58 of the different stator phases 22 are polarized at slightly different times in each cycle, which evens forces out across the axial length of the electric machine 10 for smooth torque delivery over time. As shown, each stator phase 22 is coaxial with the common axis CA, and coaxial with the other stator phases 22. Each circular array of teeth 58 of each flux ring 44 is coaxial with common axis CA. Each coil 26 is coaxial with the common axis CA. The stator phases 22 can be referred to as an A-phase, a B-phase, and a C-phase depending on the electrical signal provided to that phase.

[0102] FIG. 7 is a simplified schematic diagram showing a plurality of stator phases 22a- 22c in which different stator phases 22 can be common configured. In the example shown, stator 14 includes a pair of stator phases 22a, a pair of stator phases 22b, and a pair of stator phases 22c. Three respective signals are delivered to the six stator phases 22. A signal, which can be referred to as an A-signal, is delivered to two stator phases 22a, a signal, which can be referred to as a B-signal, is delivered to two stator phases 22b, and a signal, which can be referred to as a C-signal, is delivered to two stator phases 22c.

[0103] The stator phases 22a can be considered to form A-phases that receive the A-signal. The stator phases 22b can be considered to form B-phases that receive the B-signal. The stator phases 22c can be considered to form C-phases that receive the C-signal. The multiple stator phases 22 that receive the same signal can be considered to from common phase sets. In the example shown, the pair of stator phases 22a forms a common phase set, the pair of stator phases 22b forms a common phase set, and the pair of stator phases 22c forms a common phase set.

[0104] Specifically, two stator phases 22a are present and each of these stator phases 22a receive the same A-signal, which is out of phase by approximately 120-degrees with respect to the B-signal that is delivered to the two stator phases 22b, which is further 120-degrees offset with respect to the C-signal delivered to the two stator phases 22c. In other words, three offset signals are delivered to the stator phase 22a, stator phase 22b, and stator phase 22c respectively. The signals are generated and provision of the signals can be provided with a three-phase controller, as further explained herein.

[0105] In FIGS. 6 and 7, the stator phases 22, including their respective coils 26, are arrayed along the common axis CA. It is understood that the stator phases 22 can be arrayed along the common axis CA in any desired configuration. The stator phases 22 that form a common phase set can, in various examples, be disposed directly axially adjacent to each other (e.g., multiple A-phases adjacent to each other). In additional or alternative examples, the stator phases 22 can form a common phase set can be axially spaced such that at least one other stator phase 22 is directly axially between the stator phases 22 of the common phase set (e.g., at least one B-phase and / or C-phase axially between the multiple A-phases). For example, the stator 14 can be configured such that the stator phases 22 are arrayed along the axis as stator phase 22a, stator phase 22b, stator phase 22c (ABC); or stator phase 22a, stator phase 22c, stator phase 22b (ACB); or stator phase 22a, stator phase 22b, stator phase 22c, stator phase 22a, stator phase 22b, stator phase 22c (ABCABC); or stator phase 22a, stator phase 22b, stator phase 22c, stator phase 22c, stator phase 22b, stator phase 22a (ABCCB A); or stator phase 22a, stator phase 22a, stator phase 22b, stator phase 22b, stator phase 22c, stator phase 22c (AABBCC); among other arrangement options.

[0106] FIG. 8 shows a partial schematic view showing a face of a stator phase 22. The view of FIG. 8 is looking at the stator phase 22 from the air gap between the stator 14 and the rotor 12. FIG. 8 is labeled and represented to demonstrate concepts further illustrated in the subsequent figures. Teeth 58 are shown on opposite sides of the coil 26 representing two flux rings 24a, 24b of the stator phase 22. A coil 26 is shown between the two flux rings 24a, 24b. The direction of current at one instant in time is indicated along the coil 26. At the moment illustrated in FIG. 6, teeth 58 of flux ring 24a are polarized with a first polarity Pl (one of north and south) and the teeth 58 of flux ring 24b are polarized with a second polarity P2 (the other one of north and south). The tooth face 66 of each tooth 58 is oriented into the air gap 30. The teeth 58 of flux ring 24a are disposed on an opposite axial side of coil 26 from teeth 58 of flux ring 24b. In various examples, the teeth 58 of each flux ring 24a, 24b do not project axially over the coil 26 and do not radially overlap with the coil 26 relative to the common axis CA. It is understood that the teeth 58 of each flux ring 24a, 24b can, in various examples, project axially over the coil 26 to radially overlap with the coil 26 relative to the common axis CA.

[0107] The teeth 58 of flux ring 24a are aligned axially with the trenches formed between adjacent teeth 58 of flux ring 24b. Similarly, the teeth 58 of flux ring 24b are aligned axially with trenches formed between adjacent teeth 58 of flux ring 24b.

[0108] FIG. 9A is a schematic illustration showing a stator 14 with three stator phases 22a- 22c. FIG. 9B is a graph illustrating provision of signals to the multiple stator phases 22. FIG. 9A shows a stator 14 including three stator phases 22a-22c. Three electrically offset signals (signal 70a forming the A-signal, signal 70b forming the B-signal, and signal 70c forming the C-signal) are provided to the stator phases 22a-22c, respectively. The signals 70a-70c are respectively driven through stator phases 22a-22c and combined in a common terminal 72. The common terminal 72 will be understood as a common electrical line similar to ground. It will be understood that while the direction of the current is shown at one point in time, the alternating current signals reverse direction in each cycle.

[0109] As shown in FIG. 9 A, the teeth 58 of each flux ring 24 are not directly axially aligned with the teeth 58 of any other flux ring 24 of the other two phases 22. The teeth 58 of the flux ring 24a are not directly axially aligned with the teeth 58 of any of flux ring 24b, flux ring 24c, flux ring 24d, flux ring 24e, and flux ring 24f. The teeth 58 of a flux ring 24 can axially overlap with the teeth 58 of other flux rings 24, but that axial overlap is not across a full width of the tooth 58. Such a configuration can inhibit inductive coupling and can thereby reduce heat generation and increase operational efficiency.

[0110] FIG. 9B illustrates the three signals 70a-70c being offset relative to each other. FIG. 9B also illustrates the signal sum 74 that is a combination of the multiple signals at any given moment in time. As shown, the offset signals 70a-70c provide for an even signal sum 74 that provides for efficient and smooth operation of stator 14. The signals 70a-70c are sent through the respective coils 26 of the stator phases 22a-22c. In the illustrated graph, the trace for each signal 70a-70c represents the current. The vertical axis represents the normalized current and the horizontal axis represents the electrical degrees. The three signals 70a-70c are 120-degrees out of phase with respect to each other in the example shown.

[0111] FIG. 10 shows a schematic illustration of a six-phase electric machine having two of each of three different types of phases (stator phase 22a, stator phase 22b, stator phase 22c). The two stator phases 22a form A-phases, the two stator phases 22b form B-phases, an the two stator phases 22c form C-phases. In the example shown, the stator phases 22 are arrayed in a configuration of stator phase 22a, stator phase 22b, stator phase 22c, stator phase 22a, stator phase 22b, stator phase 22c along the common axis CA. As such, the stator 14 can be considered to have an ABCABC phase configuration.

[0112] The common phases (e.g., stator phases 22a are common with each other; stator phases 22b are common with each other; and stator phases 22c are common with each other) are wired together for common operation. In the example shown, the common phases are wired in parallel with respect to each other such that the same signal is sent through the common phases at the same time. For example, the signal 70a (FIG. 9B) can be sent through the two stator phases 22a at the same time; the signal 70b (FIG. 9B) can be sent through the two stator phases 22b at the same time; and the signal 70c (FIG. 9B) can be sent through the two stator phases 22c at the same time. As such, the six stator phases 22 are wired in parallel.

[0113] Wiring the six phases of the stator 14 in parallel provides for ease of scaling of the electric machine 10. In some examples, each stator phase 22 can be formed as a discrete module that includes the flux rings 24 and coil 26 of that stator phase 22. The module can be a single component, such as held together by potting compound, at least partially within a housing, etc. The modules can be stacked and then wired together to form an electric machine 10 having any desired configuration. In some examples, each module can be formed identical to each other module and the modules can be clocked relative to each other about the common axis CA to place each stator phase 22 in a desired configuration for receiving the offset electric signals (e.g., in a configuration to receive the A-signal, B- signal, or C-signal). Such a configuration facilitates quick and efficient formation of the stator 14 and allows for powering multiple phases, including more than three, with a three- phase controller.

[0114] In some examples, coils 26 can be disposed in parallel within a single stator phase 22. For example, the coil 26 of a single stator phase 22 can be formed by multiple discrete coil assemblies, which can be disposed in parallel between the flux rings 24 of that stator phase 22. Such a configuration can reduce eddy currents and associated losses. The electric machine 10 including six stator phases 22 with the stator phases 22 in a common phase set wired in parallel provides for a robust configuration. Electric machine 10 can operate in a limp home capacity in the event of an issue or failure of a stator phase 22. For example, if a first stator phase 22a is non-operational, the second stator phase 22a will continue to receive the A-signal and will continue to emit flux that drives rotation of the rotor 12. The signal being provided in parallel allows for continued operation and driving of the rotor 12 by electrical signals that are 120-degrees offset. As such, the electric machine 10 can continue to operate if needed prior to shutting down for maintenance and / or repair.

[0115] FIG. 11 is a schematic diagram of electric machine 10 but with a different wiring configuration from that shown in FIG. 10. In FIG. 10, electric machine 10 includes multiple stator phases 22 that are wired in parallel. In FIG. 11, electric machine 10 includes multiple stator phases 22 that are wired in series. While the array of phases shown in FIG. 11 is still stator phase 22a, stator phase 22b, stator phase 22c, stator phase 22a, stator phase 22b, stator phase 22c (i.e., ABCABC) along the common axis CA, the common phases (e.g., multiple stator phases 22a) are wired in series instead of in parallel. As such, one terminal of the first stator phase 22a is connected to one terminal of the second stator phase 22a, one terminal of the first stator phase 22b is connected to one terminal of the second stator phase 22b, and one terminal of the first stator phase 22c is connected to one terminal of the second stator phase 22c. The stator phases 22 shown in FIG. 11 are not wired in parallel with each other.

[0116] FIG. 12 is a schematic illustration of the six-phase electric machine 10 similar to that shown in FIGS. 10 and 11; however, the stator phases 22 as shown in FIG. 12 are in a different axial arrangement. The common phases are shown as wired in parallel, though it is understood that such common phases can be wired in series. In the example shown in FIG. 12, the stator phases 22 are configured such that stator phases within common phase sets are disposed axially adjacent to one another. The arrangement of stator phases 22 is such that common phases are adjacent to one another / The arrangement shown is stator phase 22a, stator phase 22a, stator phase 22b, stator phase 22b, stator phase 22c, stator phase 22c (i.e., AABBCC).

[0117] As shown between FIGS. 10-12, stator 14 can be configured such that common phases can be disposed axially adjacent to one another or can be axially spaced such that a stator phase 22 other than one of the common phases is disposed directly axially between the common phases. In various examples, at least one set of the common phases includes axially adjacent stator phases 22 and at least one other set of the common phases includes axially spaced stator phases 22. For example, the stator 14 can be configured with stator phases 22 axially stacked as stator phase 22a, stator phase 22b, stator phase 22c, stator phase 22c, stator phase 22b, stator phase 22a (ABCCBA). In such an example, the stator 14 includes two axially spaced common phase sets (the common phase sets including stator phases 22a and stator phases 22b) and one axially adjacent common phase set (the common phase set including stator phases 22c).

[0118] FIG. 13A shows a schematic illustration of electric machine 10'. FIG. 13B is a graph illustrating driving electrical signals for a two-phase electric machine 10'. Electric machine 10' includes two stator phases 22a, 22b in the example shown and does not include a third stator phase (e.g., a stator phase 22c). Electric machine 10' is configured to receive two driving signals, unlike electric machine 10 previously discussed that receives three driving signals. Electric machine 10' is substantively similar to the three-phase (or multiple of three) electric machine 10 previously discussed, except electric machine 10' includes two (or a multiple of two) stator phases 22 that are configured to receive two driving signals. Electric machine 10' includes two (or a multiple of two) common phase sets. In the example shown, each common phase set includes a single stator phase 22, though in other examples the common phase sets can include more than one stator phase 22. Components that are similar or the same as between electric machine 10' and electric machine 10 are indicated with the same reference number. It is understood that the discussion of such components with regard to such components with regard to electric machines 10 having three (or multiple of three) stator phases 22 is equally applicable to the discussion of electric machine 10' and some may be omitted for brevity.

[0119] A two (or multiple of two) phase electric machine 10' can be beneficial for lower torque, higher speed, a more compact configuration, and / or lower cost, amongst other applications. In the two-phase electric machine 10', the stator 14 includes two coils 26 that are associated with the two stator phases 22a, 22b. It may be advantageous to drive a three- phase signal through the two-phase electric machine 10' as a three-phase controller is generally more commonly manufactured than a two-phase controller. As such it can provide cost and material savings by controlling operation of a two-phase electric machine 10' with a three-phase controller. The third signal (e.g., the C-signal) is provided to a bypass line 76 that is not associated with a stator phase 22 of the electric machine 10'. The bypass line 76 is connected to common terminal 72 such that the third signal is driven into the common terminal 72 without first being driven through a stator coil 26. The first and second signals (e.g., the A-signal and the B-signal) are driven across respective stator phases 22a, 22b.

[0120] In the example shown, the stator phases 22a, 22b are offset from each other and not axially aligned, though it is understood that not all configurations are so limited. The stator phase 22a includes flux rings 24a, 24b that each include an array of teeth 58. The stator phase 22b includes flux rings 24c, 24d that each include an array of teeth 58. The stator phases 22a, 22b are axially misaligned with each other such that no tooth 58 of any flux ring 24 of the two stator phases 22a, 22b is fully axially aligned with any other tooth 58 of any other flux ring 24. As shown, the teeth 58 of a flux ring 24 can axially overlap with the teeth 58 of multiple other flux rings 24 (e.g., teeth 58 of flux ring 24c axially overlap with teeth 58 of both flux rings 24a, 24b) but such axially overlapping teeth 58 are circumferentially offset such that the teeth 58 partially, but not fully, axially overlap. With the partial overlap, a projection of the tooth 58 axially outward would not fully cover the other teeth 58 that that tooth 58 axially overlaps with. Such a configuration can inhibit inductive coupling and thereby reduce undesired heating while providing improved operating efficiency.

[0121] The controller provides three electrical signals that are utilized to cause the stator 14 to drive rotation of the rotor 12 on the common axis CA. FIG. 13B shows a graph of the electric current of the three signals 70a, 70b, 70c. The relative electrical currents are shown in on the vertical axis and the electrical angle is shown on the horizontal axis. As shown in FIG. 9B above, the three signals 70a, 70b, 70c are provided 120-degrees out of phase for a three, or multiple of three, electric machine 10'. As shown in FIG. 13B, the driving signals (signals 70a, 70b for the two-phase electric machine 10') are offset by 90- degrees from each other. Specifically, the signal 70b is offset 90-degrees from the signal 70a. It is understood that the driving signals can be offset by between about 80-degrees to 100-degrees.

[0122] The third signal (signal 70c) provides a non-driving signal and is not provided to a stator phase 22 to drive rotation of the rotor 12. Instead, the non-driving signal can be considered to bypass the stator 14. Signal 70c is a non-driving signal in the example shown. The non-driving signal 70c is offset from the driving signals 70a, 70b. In the example shown, the non-driving signal 70c is offset by 225-degrees from driving signal 70b. It is understood that the non-driving signal 70c can be offset by between about 215-degrees to 235-degrees from the driving signal 70b. The non-driving signal 70c is offset by 135- degrees from driving signal 70a. In the example shown the non-driving signal 70c is at a balanced location relative to the first driving signal 70a and the second driving signal 70b. The peak of signal 70c is disposed 135-degrees after the peak of the driving signal 70a and is also disposed 135-degrees before the peak of the driving signal 70b.

[0123] In the example shown, the non-driving signal 70c is offset from the first driving signal 70a by a greater extent than the second driving signal 70b is offset from the first driving signal 70a. In the example shown, the non-driving signal 70c is offset from the second driving signal 70a by 1.5 times the offset of the first driving signal 70a from the second driving signal 70b.

[0124] As shown in FIG. 13B, the amplitudes can vary between the driving and non-driving signals. The non-driving signal 70c can have a greater amplitude than the driving signals 70a, 70b. As such, the non-driving signal 70c can have a higher peak current than either of the driving signals 70a, 70b. The greater peak amplitude of the non-driving signal 70c relative to the driving signals 70a, 70b balances with the driving signals 70a, 70b that are disposed offset by fewer degrees than when three driving signals are provide to a three (or multiple of three) phase electric machine.

[0125] While a two-phase machine 10' is shown in FIGS. 13A and 13B, it is understood that a four-phase machine, or a machine of any larger size being a multiple of two (e.g., six-phase, eight-phase, etc.), is contemplated to be within the scope of this disclosure. The common phases can be wired in series or in parallel, such as previously shown for the six- phase machines, with the same signal being delivered through the common phases.

[0126] FIG. 14 is a schematic illustration of electric machine 10' configured as a four-phase electric machine. The electric machine 10' includes common phase sets having more than one stator phase 22. In the example shown, electric machine 10' is formed as a four-phase electric machine that includes two common phase sets. The first common phase set includes stator phases 22a and the second common phase set includes stator phases 22b.

[0127] In the example shown, electric machine 10' is configured such that the stator phases 22 within a common phase set are wired in parallel. The two stator phases 22a are wired in parallel. The two stator phases 22b are wired in parallel. As discussed above, electric machine 10' is configured for receiving two driving signals but as shown can be operated by a three-phase controller. The first driving signal (e.g., signal 70a) is provide to the stator phases 22a of the first common phase set in parallel. The second driving signal (e.g., signal 70b) is provided to the stator phases 22b of the second common phase set in parallel. The non-driving signal (e.g., signal 70c) is provided but does not flow through a coil 26 of the stator 14. Instead, the non-driving signal bypasses the stator phases 22 of the stator 14 and is provided to common terminal 72.

[0128] FIG. 15 is a schematic illustration of electric machine 10' formed as a four-phase electric machine. The configuration of electric machine 10' shown in FIG. 15 is similar to that in FIG. 14 except that the common phases are wired in series instead of in parallel. The electric machine 10' includes common phase sets having multiple stator phases 22. In the example shown, electric machine 10' is formed as a four-phase electric machine that includes two common phase sets. The first common phase set includes a pair of stator phases 22a and the second common phase set includes a pair of stator phases 22b.

[0129] In the example shown, electric machine 10' is configured such that the stator phases 22 within a common phase set are wired in series. The two stator phases 22a are wired in series. The two stator phases 22b are wired in series. As discussed above, electric machine 10' is configured for receiving two driving signals but as shown can be operated by a three- phase controller. The first driving signal (e.g., signal 70a) is provide to the stator phases 22a of the first common phase set in series. The second driving signal (e.g., signal 70b) is provided to the stator phases 22b of the second common phase set in series. The nondriving signal (e.g., signal 70c) is provided but does not flow through a coil 26 of the stator 14. Instead, the non-driving signal bypasses the stator phases 22 of the stator 14 and is provided to the common terminal 72.

[0130] In FIG. 15, the stator phases 22 within a common phase set are disposed axially adjacent to each other. In the example shown, the multiple stator phases 22a are disposed directly axially adjacent to each other and the multiple stator phases 22b are disposed directly axially adjacent to each other. The stator 14 is configured in an AABB configuration, though it is understood that other configurations are possible. For example, stator 14 can be configured as AB AB or ABBA.

[0131] In the example shown, the stator phases 22 within a common phase set are disposed in a mirrored configuration. The stator phases 22 within a common phase set are wired such that the current flows in a reverse circumferential within each of the serially wired stator phases 22. This is different from the configuration shown in FIG. 11 in which the stator phases 22 within a common phase set are wired for the current to flow in a common circumferential direction within each stator phase 22 of the common phase set. It is understood that the four-phase electric machine 10' shown in FIG. 15 can be wired such that the current flows in a common circumferential direction through the serially connected stator phases 22 of a common phase set, similar to that shown in FIG. 11. The stator phases 22 within the common phase sets shown in FIG. 15 can be considered to be in a mirrored configuration. With the stator phases 22 in the mirrored configuration, axially adjacent ones of the teeth 58 are fully axially aligned with each other. In the example shown, the common phase set including stator phases 22a has a first stator phase 22a and a second stator phase 22a. Each stator phase 22a includes a first flux ring 24a and a second flux ring 24b. The flux rings 24b are disposed directly axially adjacent to each other such that the two flux rings 24b are axially between the coils 26 of the multiple stator phases 22a. No coil 26 or other flux ring 24 is disposed axially between the two flux rings 24b. The stator phases 22a are in a mirrored configuration in that the teeth 58 of the first flux ring 24b are directly axially aligned with the teeth 58 of the second flux ring 24b. Further, the teeth 58 of the first flux ring 24a are directly axially aligned with the teeth 58 of the second flux ring 24a. The flux ring configuration of the stator phases 22a is flipped in that the first flux ring 24b is spaced in axial direction ADI from the first flux ring 24a while the second flux ring 24b is spaced in axial direction AD2 from the second flux ring 24a.

[0132] The polarity of the various teeth 58 of the stator phases 22a at a moment in time is shown in FIG. 15 by way of example. As shown, the teeth 58 of the flux rings 24a have the same polarity (one of north and south, indicated as Pl) and the teeth 58 of the flux rings 24b have the same polarity (the other one of north and south, indicated as P2). The reversed flow direction through the serially connected stator phases 22 within a common phase set causes the polarities to be flipped on opposite axial sides of the coil 26 as between the multiple stator phases 22 within the common phase set. In the example shown, the axially outermost flux rings 24 have the same polarity and the axially innermost flux rings 24 have the same polarity.

[0133] The stator phases 22 within a common phase set being in the mirrored configuration can provide significant advantages. The teeth 58 of the adjacent flux rings 24 (e.g., flux rings 24b of stator phases 22a) have the same polarity during operation of the stator 14. The common phase set can be configured such that the axially adjacent flux rings 24 within the common phase set are formed as a single component. For example, the flux rings 24b of the two stator phases 22a can be formed monolithically with each other, among other options. Such a configuration can provide for a more compact configuration of stator 14 and thus of the electric machine 10'. Such a configuration can also simplify manufacturing and reduce cost as the central teeth (e.g., teeth 58 of flux rings 24b of stator phases 22a) can be formed from a single piece, such as a single stamping or single layering of lamina sheets, among other options. The central teeth are disposed axially between the serially connected coils 26.

[0134] While the stator phases 22 within a common phase set are shown as serially connected while in a mirror configuration, it is understood that not all examples are so limited. Some examples of a two (or multiple of two) phase electric machine 10' includes stator phases 22 that are serially connected and disposed in a stacked, not mirrored, configuration, similar to the configuration shown in FIG. 11.

[0135] FIG. 16 is a schematic diagram of a three-phase controller 78. As discussed above, an electric machine including two stator phases, or a multiple of two stator phases, can be controlled by a three-phase controller 78. Three-phase controller 78 includes a set of six switches 80a-80f (collectively herein “switch 80” or “switches 80”). The switches 80 are turned on and off to control current flow relative to the coils 26 of the stator 14. As shown, the line 82a, which is associated with switch 80a and switch 80d, is connected to a first coil 26a (e.g., the coil or coils of the one or more A-phases) and line 82b, which is associated with switch 80c and switch 80f, is connected to a second coil 26b (e.g., the coil or coils of the one or more B-phases). Line 82c is not connected to a coil to provide electrical energy to a coil. Instead, line 82c can provide return current for balancing with signals provides to the first coil 26a and the second coil 26b. Line 82c is associated with switch 80e and switch 80b. In the example shown, the multiple lines 82a-82c are connected in a Y- configuration, though it is understood that not all examples are so limited.

[0136] During operation, the switches 80a-80f are opened and closed to control electrical power to the stator 14. As discussed above with regard to FIG. 13C, the signals 70a, 70b that are provided to the coils 26a, 26b of the different stator phases 22 are out of phase with each other but are spaced closer together than signals provided to a three (or multiple of three) phase electric machine. The signal 70c has a greater amplitude than the signals 70a, 70b which balances with the closer spacing of the driving signals when powering a two- phase electric machine. The non-driving signal provided through line 82c goes to the returns from the two stator phases 22 of the electric machine 10', and the greater magnitude of the current in the non-driving signal balances with the closely spaced (e.g., about 90- degrees)_driving currents to provide efficient operation of the electric machine 10'.

[0137] FIG. 17 is a schematic diagram of a two-phase controller 84. As shown, the two phase controller 84 includes switches 86a-86h (collectively herein “switch 86” or “switches 86”) for a total of eight switches 86. The switches 86 are turned on and off to control current flow relative to the coils 26 of the stator 14. A first subset of four switches (switches 86a-86d) are associated with the first coil 26a and a second subset of four switches (switches 86e-86h) are associated with the second coil 26b. The four switches 86a-86d control current flow through coil 26a and the four switches 86e-86h control current flow through coil 26b.

[0138] With regard to FIGS. 16 and 17, driving a two, or multiple of two, phase electric machine 10' with a three-phase controller 78 provides significant advantages. The three- phase controller 78 includes six switches 80 to control current flow while the two-phase controller 84 includes eight switches 86 to control current flow. The three-phase controller 78 includes fewer switches than the two-phase controller 84, providing cost and material savings. The non-driving signal output by the three-phase controller 78 balances with the current of the driving signals, facilitating operation of the two-phase (or multiple of two) electric machine 10'. As such, a three-phase controller 78 can be less expensive than a dedicated two-phase controller 84, such that it is more advantageous to operate a two-phase electric machine with a three-phase controller 78.

[0139] A three-phase controller 78 driving a two-phase electric machine 10' is advantageous for higher speed applications. A two-phase electric machine 10' will spin faster than a wye-connected three-phase electric machine 10 when the amplitude of the non-driving and highest- amplitude signal 70c for the two-phase electric machine is the same as the amplitudes of signals 70a, 70b, and 70c for the three-phase electric machine 10. In this case, signals 70a and 70b of the two-phase electric machine are of a lower amplitude and balanced with signal 70c.

[0140] While a fan embodiment is shown herein, it is understood that the features of this disclosure can be applied to an electric machine of any application, including non-fan applications. It is further understood that any aspect discussed herein with regard to a particular example may be mixed as between the different embodiments and features.

[0141] While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMS:

1. An electric rotational machine comprising: a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases, each stator phase of the plurality of stator phases comprising: at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases.

2. The electric rotational machine of claim 1, wherein: the plurality of phases comprises a plurality of common phase sets, the plurality of common phase sets including a first common phase set, a second common phase set, and a third common phase set; and the controller delivers the plurality of electrical signals comprising a first signal, a second signal, and a third signal such that the first signal, the second signal, and the third signal are respectively delivered to the first common phase set, the second common phase set, and the third common phase set.

3. The electric rotational machine of claim 2, wherein the first common phase set includes at least two first stator phases, the second common phase set includes at least two second stator phases, and the third common phase set includes at least two third stator phases.

4. The electric rotational machine of claim 3, wherein the first common phase set includes two first stator phases, the second common phase set includes two second stator phases, and the third common phase set includes two third stator phases.

5. The electric rotational machine of claim 3, wherein the first common phase set includes three first stator phases, the second common phase set includes three second stator phases, and the third common phase set includes three third stator phases..

6. The electric rotational machine of any one of claims 3-5, wherein the at least two first stator phases are wired in parallel with each other, the at least two second stator phases are wired in parallel with each other, and the at least two third stator phases are wired in parallel with each other.

7. The electric rotational machine of any one of claims 3-5, wherein the at least two first stator phases are wired in series with each other, the at least two second stator phases are wired in series with each other, and the at least two third stator phases are wired in series with each other.

8. The electric rotational machine of any one of claims 2-7, wherein the second signal is delivered between 110-degrees and 130-degrees offset from the first signal, and the third signal is delivered 110-degrees to 130-degrees offset from the second signal.

9. The electric rotational machine of any one of claims 2-8, wherein the plurality of stator phases are arrayed along the axis as a first A-phase, a first B -phase, a first C-phase, a second A-phase, a second B-phase, and a second C-phase.

10. The electric rotational machine of any one of claims 2-8, wherein the plurality of stator phases are arrayed along the axis as a first A-phase, a first B-phase, a first C-phase, a second C-phase, a second B-phase, and a second A-phase.

11. The electric rotational machine of any one of claims 2-8, wherein the plurality of stator phases are arrayed along the axis as a first A-phase, a second A-phase, a first B-phase, a second B-phase, a first C-phase, and a second C-phase.

12. The electric rotational machine of claim 1, wherein the plurality of stator phases comprises a first common phase set to which a first signal of the plurality of electrical signals is delivered, a second common phase set to which a second signal of the plurality of electrical signals is delivered, and wherein the plurality of stator phases does not include a stator phase to which the third electrical signal is delivered.

13. The electric rotational machine of claim 12, wherein the third signal is delivered to a common terminal of the plurality of stator phases without the third signal being directly delivered through any stator phase of the plurality of stator phases.

14. The electric rotational machine of claim 12, wherein the third signal is delivered to a common terminal of the plurality of stator phases without the third signal being directly delivered through any coil of the plurality of stator phases.

15. The electric rotational machine of any one of claims 13 and 14, wherein the first common phase set includes at least two first stator phases and the second common phase set includes at least two second stator phases..

16. The electric rotational machine of claim 15, wherein the first common phase set includes two first stator phases and the second common phase set includes two second stator phases.

17. The electric rotational machine of claim 15, wherein the first common phase set includes three first stator phases and the second common phase set includes three second stator phases.

18. The electric rotational machine of any one of claims 12-17, wherein the at least two first stator phases are wired in parallel with each other, and the at least two second stator phases are wired in parallel with each other.

19. The electric rotational machine of any one of claims 12-17, wherein the at least two first stator phases are wired in series with each other, and the at least two second stator phases are wired in series with each other.

20. The electric rotational machine of any of claims 12-19, wherein the second signal is delivered between 80-degrees and 100-degrees offset from the first signal.

21. The electric rotational machine of claim 20, wherein the third signal is delivered between 215-degrees and 235-degrees offset from the second signal.

22. The electric rotational machine of any one of claims 12-21, wherein the plurality of stator phases are arrayed along the axis as a first A-phase, a first B -phase, a second B-phase, and a second A-phase.

23. The electric rotational machine of any one of claims 12-21, wherein the plurality of stator phases are arrayed along the axis as a first A-phase, a first B-phase, a second A-phase, and a second B-phase.

24. The electric rotational machine of any one of claims 12-21, wherein the plurality of stator phases are arrayed along the axis as a first A-phase, a second A-phase, a first B-phase, and a second B-phase.

25. The electric rotational machine of any one of claims 12-21, wherein the third signal has a greater amplitude than the first signal.

26. The electric rotational machine of claim 25, wherein the third signal has a greater amplitude than the second signal.

27. The electric rotational machine of any one of claims 25 and 26, wherein an amplitude of the first signal matches an amplitude of the second signal.

28. The electric rotational machine of any one of claims 12-21, wherein the first common phase set includes a pair of stator phases that are disposed in a mirrored configuration.

29. The electric rotational machine of claim 28, wherein the pair of stator phases are wired in series.

30. The electric rotational machine of claim 29, wherein each stator phase of the pair of stator phases includes a first flux ring, a second flux ring, and the coil disposed between the first flux ring and the second flux ring, and wherein the pair of stator phases are disposed such that a first phase of the pair of stator phases is adjacent to a second phase of the pair of stator phases and such that the second flux ring of the first phase of the pair of stator phases is axially adjacent to the second flux ring of the second phase of the pair of stator phases.

31. The electric rotational machine of claim 30, wherein the second flux ring of the first phase of the pair of stator phases and the second flux ring of the second phase of the pair of stator phases are disposed axially between the coil of the first phase of the pair of stator phases and the coil of the second phase of the pair of stator phases.

32. The electric rotational machine of any one of claims 30 and 31, wherein the pair of stator phases are wired in series such that the first signal flows in opposite circumferential directions through the coil of the first phase of the pair of stator phases and the coil of the second phase of the pair of stator phases.

33. The electric rotational machine of any one of claims 30-32, wherein the second flux ring of the first phase of the pair of stator phases and the second flux ring of the second phase of the pair of stator phases are simultaneously and commonly polarized.

34. The electric rotational machine of any one of claims 1-33, wherein the plurality of electrical signals are sinusoidal.

35. The electric rotational machine of any one of claims 1-34, wherein the electric rotational machine is a motor.

36. An electric rotational machine comprising: a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis;a stator comprising a plurality of stator phases, each stator phase of the plurality of stator phases comprising: at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases; wherein the controller is a three-phase controller configured to provide a first electrical signal, a second electrical signal, and a third electrical signal; and wherein the first electrical signal is provided to a first stator phase of the plurality of stator phases, the second electrical signal is provided to a second stator phase of the plurality of stator phases, and the third electrical signal is not provided to any stator phase of the plurality of stator phases.

37. The electric rotational machine of claim 36, wherein an amplitude of the third electrical signal is greater than an amplitude of the first electrical signal and the amplitude of the third electrical signal is greater than an amplitude of the second electrical signal.

38. The electric rotational machine of any one of claims 37-38, wherein an offset between the third electrical signal and either of the first electrical signal and the second electrical signal is greater than an offset between the first electrical signal and the second electrical signal.

39. The electric rotational machine of any one of claims 36-38, wherein the wherein the plurality of stator phases includes a first common phase set having at leasttwo of the first stator phase and a second common phase set having at least two of the second stator phase.

40. The electric rotational machine of any one of claims 36-39, wherein the three-phase controller includes a plurality of switches.

41. The electric rotational machine of claim 40, wherein the plurality of switches includes six switches.

42. The electric rotational machine of any one of claims 40 and 41, wherein a first pair of the plurality of switches is associated with the first stator phase and a second pair of the plurality of switches is associated with the second stator phase.

43. The electric rotational machine of claim 42, wherein a third set of the plurality of switches controls flow of the third electrical signal.

44. An electric rotational machine comprising: a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases, each stator phase of the plurality of stator phases comprising: at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases;wherein the plurality of stator phases includes a first common phase set having at least two first stator phases and a second common phase set having at least two second stator phases; wherein the at least two first stator phases are wired in parallel; and wherein the at least two second stator phases are wired in parallel.

45. The electric rotational machine of claim 44, wherein the plurality of stator phases further includes a third common phase set having at least two third stator phases.

46. The electric rotational machine of claim 45, wherein the at least two third stator phases are wired in parallel.

47. The electric rotational machine of any one of claims 45 and 46, wherein at least one of the first common phase set the second common phase set, and the third common phase set includes axially adjacent stator phases.

48. The electric rotational machine of any one of claims 45-47, wherein at least one of the first common phase set the second common phase set, and the third common phase set includes axially spaced stator phases.

49. The electric rotational machine of any one of claims 44-46, wherein the at least one of the first common phase set and the second common phase set includes axially adjacent stator phases.

50. The electric rotational machine of any one of claims 44-46, wherein at both the first common phase set and the second common phase set include axially adjacent stator phases.

51. An electric rotational machine comprising: a rotor that rotates coaxial about an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of stator phases, each stator phase of the plurality of stator phases comprising:at least one coil wound around the axis such that the axis extends through the at least one coil; and a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the stator phase located between the pair of circular arrays of teeth such that electrical energy delivered through the at least one coil electromagnetically polarizes teeth of the pair of circular arrays of teeth; and a controller which delivers a plurality of electrical signals respectively to the plurality of stator phases; wherein the plurality of stator phases includes a first common phase set having at least two first stator phases and a second common phase set having at least two second stator phases; wherein the at least two first stator phases are wired in series; and wherein the at least two second stator phases are wired in series.

52. The electric rotational machine of claim 51, wherein the plurality of stator phases further includes a third common phase set having at least two third stator phases.

53. The electric rotational machine of claim 52, wherein the at least two third stator phases are wired in series.

54. The electric rotational machine of any one of claims 52 and 53, wherein at least one of the first common phase set the second common phase set, and the third common phase set includes axially adjacent stator phases.

55. The electric rotational machine of any one of claims 52-54, wherein at least one of the first common phase set the second common phase set, and the third common phase set includes axially spaced stator phases.

56. The electric rotational machine of any one of claims 51-53, wherein the at least one of the first common phase set and the second common phase set includes axially adjacent stator phases.

57. The electric rotational machine of any one of claims 51-53, wherein at both the first common phase set and the second common phase set include axially adjacent stator phases.

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