Motor

Abstract

To provide soft magnetic materials having properties favorable for use in energy efficient devices and to provide a motor.SOLUTION: The motor includes: a stator 2120 including at least one core 2140 and a cutout 2135 continuously and circumferentially running on an outer circumferential surface 2130 of an outer wall; a coil 2150; a rotor; at least one magnet disposed between the stator and the rotor; and a conical air gap between the stator and the at least one magnet. The outer wall ends at an outer edge of the coil. A separation plane normal to an axis of rotation extends through the stator and the rotor. The coil, the at least one magnet, and the conical air gap are together configured to allow flux flow between the stator and the rotor not to cross the separation plane in a three-dimensional flux pattern.SELECTED DRAWING: Figure 35C

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION The exemplary, non-limiting embodiments disclosed herein relate generally to magnetic materials and structures incorporating such materials, and more particularly to soft magnetic materials having properties suitable for use in energy-efficient devices.

[0002] Automated mechanical devices commonly use electric motors to provide linear or rotary motion to various moving elements of the device. The electric motors used typically include a rotating element assembled with a fixed element. A magnet is positioned between the rotating and fixed elements. The fixed element has a soft iron core around which a coil is wound and which is positioned adjacent to the magnet.

[0003] In operation, an electric motor generates a magnetic field when current flows through the coil, which acts on the magnet. When the magnetic field acts on the magnet, it pushes one side of the rotating element and pulls the other side of the rotating element, causing the rotating element to rotate relative to the fixed element. Rotational efficiency is based, at least in part, on the properties of the materials used in the construction of the electric motor. Abstract

[0004] The following summary is merely exemplary and is not intended to limit the scope of the claims. First, a motor is disclosed. The motor comprises: a stator having at least one core and an axially extending outer wall; a coil wound around the at least one core; a rotor having rotor poles and rotatably mounted relative to the stator; at least one magnet mounted between the stator and the rotor; a conical air gap between the stator and the at least one magnet; Equipped with the end of the outer wall is lower than, equal to, or exceeds the surface of the coil facing the axial direction, and the outer wall terminates at the outer edge of the coil; a dividing plane perpendicular to the axis of rotation extends through the stator and the rotor; The coil, the at least one magnet, and the conical air gap are configured together to allow magnetic flux flow between the stator and the rotor in a three-dimensional magnetic flux pattern that does not cross the dividing plane.

[0005] Also disclosed is a soft magnetic material deposited on a substrate, the soft magnetic material comprising: a plurality of iron-containing particles forming a plurality of continuous thin films having a microstructure of individual microdomains; each of the plurality of iron-containing particles has an iron core made of substantially pure iron and an insulating layer on the iron core; the insulating layer comprises an alumina layer having a concentration gradient caused by an aluminum concentration increasing from the iron core to the surface of the iron-containing particle; the plurality of iron-containing particles form agglomerates of a plurality of magnetically permeable microdomains separated from one another by insulating boundaries; the agglomerates having a plurality of contiguous micro-domains that, when thermally sprayed onto the substrate, form a continuous layer of thermally sprayed iron-containing particles; The iron-containing particles defined by the iron core and the insulating layer form a dense solid layer in which particles in the formed successive layers adhere to particles in the immediately preceding layer at a bottom contact, the bottom having a shape that matches the shape of the particle in the immediately preceding layer to which it adheres. Also disclosed is an apparatus comprising: a stator having at least one core; a coil on the at least one core; a rotor rotatably mounted within the stator; and at least one magnet mounted between the stator and the rotor, wherein the at least one core comprises the soft magnetic material.

[0006] Also disclosed is a method comprising: heating iron particles consisting essentially of pure iron; spraying the iron particles; oxidizing the iron particles to form an insulating layer comprising alumina on the iron particles to form iron oxide-containing particles; depositing the iron oxide-containing particles on a substrate to form a soft magnetic material; Including, the iron-containing particles form continuous thin films having a microstructure consisting of individual microdomains; the plurality of iron-containing particles forming agglomerates of a plurality of magnetically permeable microdomains separated from one another by insulating boundaries; the agglomerates having a plurality of continuous micro-domains that, when sprayed onto the substrate, form a continuous layer of iron particles; the plurality of iron-containing particles and the insulating layer of the plurality of iron-containing particles form a dense solid layer, the particles in the successive layers of the solid layer adhering to the particles of the immediately preceding layer at a bottom contact, the bottom having a shape that matches the shape of the particle of the adhering immediately preceding layer; The insulating layer is formed by an alumina layer having a concentration gradient caused by an aluminum concentration increasing from the iron core to the surface of the iron-containing particle, and the increase in aluminum concentration is achieved by depositing an aluminum layer on the iron particle and then heat treating it to diffuse aluminum into the iron particle and form an alloy with a varying aluminum concentration.

[0007] [1] Also disclosed is a composition comprising a plurality of iron-containing particles and an insulating layer on the iron-containing particles, the iron-containing particles defining agglomerates of magnetically permeable microdomains separated by insulating boundaries. According to another aspect, a method includes heating iron-aluminum alloy particles, thermally spraying the iron-aluminum particles, oxidizing the iron-aluminum particles, and depositing the oxidized iron-aluminum particles on a substrate. According to another aspect, an apparatus includes a stator having at least one core, a coil on the at least one core, a rotor rotatably mounted within the stator, and at least one magnet mounted between the stator and the rotor, wherein the at least one core includes a composition defined by iron-containing particles having an oxide layer disposed thereon. [2] The following soft magnetic material is also disclosed. This soft magnetic material comprises: a plurality of iron-containing particles forming a plurality of successive microdomains grown from a preceding microdomain, the iron-containing particles substantially maintaining an acicular ratio as the successive microdomains are formed; an insulating layer on the iron-containing particles, the insulating layer comprising an oxide; Including, the soft magnetic material is an agglomeration of magnetically permeable microdomains separated by insulating boundaries; the agglomerate comprises the plurality of contiguous micro-domains, the plurality of contiguous micro-domains forming a continuous layer of thermally sprayed iron-containing particles; the plurality of iron-containing particles and the plurality of particles defined by the insulating layer of the plurality of iron-containing particles form a high-density solid layer, and particles in the successive layers of the solid layer have spherical tops and contact with particles in the layer formed immediately before at contact portions of their bottoms, and the bottoms have a shape that matches the shape of the particles with which they are in contact; the plurality of micro-regions exhibit three-dimensional isotropy; The particles in the microscopic region are substantially completely surrounded by an insulating layer. [3] The following method is also disclosed: heating the iron-containing particles; thermally spraying the iron-containing particles; oxidizing the iron-containing particles to form an insulating layer comprising alumina on the iron-containing particles; depositing the oxidized iron-containing particles on a substrate to form a soft magnetic material; Including, the iron-containing particles form continuous thin films having a microstructure consisting of individual microdomains; the plurality of iron-containing particles forming agglomerates of a plurality of magnetically permeable microdomains separated from one another by insulating boundaries; the agglomerates sprayed onto the substrate have the continuous thin film forming a continuous layer of iron-containing particles, the iron-containing particles substantially maintaining an acicular ratio as the continuous thin film is formed; the iron-containing particles and the insulating layer of the iron-containing particles form a dense solid layer, wherein particles in the successive layers of the solid layer adhere to particles in a previously formed layer at contact points at the bottom, and the bottom has a shape that matches the shape of the particles to which they adhere; The iron-containing particles have a body-centered cubic structure, which provides three-dimensionally isotropic magnetic properties.

[0008] The following motor is also disclosed: a stator having at least one core and an axially extending outer wall; a coil wound around the at least one core; a rotor having rotor poles and rotatably mounted relative to the stator; at least one magnet mounted between the stator and the rotor; a conical air gap between the stator and the at least one magnet; and the height of the end of the outer wall is less than, equal to, or exceeds the height of the face of the coil facing the axial direction, and the outer wall terminates at the outer edge of the coil; a dividing plane perpendicular to the axis of rotation extends through the stator and the rotor; The coil, the at least one magnet, and the air gap are configured to allow magnetic flux to flow between the stator and the rotor, and the magnetic flux flow exhibits a three-dimensional magnetic flux pattern such that the magnetic flux flow does not cross the dividing plane. These and other features are described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of one exemplary embodiment of a soft magnetic material having an aggregate microstructure of magnetically permeable microdomains separated by insulating boundaries.

[0010] [Figure 2]2A and 2B are schematic diagrams illustrating the deposition process of an iron-aluminum alloy to form the soft magnetic material of FIG.

[0011] [Figure 3] 3A-C are photographs of the microstructures of soft magnetic materials produced using various deposition methods.

[0012] [Figure 4] Figures 4A-C are photographs of structures made using soft magnetic materials.

[0013] [Figure 5] 5A-D are schematic illustrations of various forms of soft magnetic materials.

[0014] [Figure 6A] 1 is a schematic diagram of a ring structure made using soft magnetic material.

[0015] [Figure 6B-D] Figures 6B-D are photographs of the microstructure of the soft magnetic material, showing isotropy in the XZ, YZ, and XY planes.

[0016] [Figure 7] 1 is a perspective cross-sectional view of an exemplary embodiment of a motor incorporating soft magnetic material.

[0017] [Figure 8] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0018] [Figure 9] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0019] [Figure 10A] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0020] [Figure 10B] FIG. 10B is a perspective view of an exemplary embodiment of a stator pole of the motor of FIG. 10A.

[0021] [Figure 11] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material. [Figure 12] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material. [Figure 13] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material. [Figure 14A] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0022] [Figure 14B] FIG. 14B is a perspective cross-sectional exploded view of the motor of FIG. 14A.

[0023] [Figure 15A] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0024] [Figure 15B] FIG. 15B is a perspective cross-sectional exploded view of the motor of FIG. 15A.

[0025] [Figure 16A] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0026] [Figure 16B] FIG. 16B is a perspective cross-sectional exploded view of the motor of FIG. 16A.

[0027] [Figure 17A] 1 is a schematic diagram of a stator cross section in one exemplary embodiment of a motor.

[0028] [Figure 17B-C] 17B-C are schematic cross-sectional views of a stator in an exemplary embodiment of a motor incorporating soft magnetic material.

[0029] [Figure 18A] FIG. 10 is a perspective cross-sectional view of another exemplary embodiment of a motor incorporating soft magnetic material.

[0030] [Figure 18B] 18B is a schematic diagram of the top view of the tapered stator poles of the motor of FIG. 18A.

[0031] [Figure 18C] FIG. 18B is a perspective cross-sectional exploded view of the motor of FIG. 18A.

[0032] [Figure 19] 1 is a schematic cross-sectional view of a motor including a soft magnetic material.

[0033] [Figure 20] 1 is a perspective cross-sectional view of an exemplary embodiment of a stator in a motor including a soft magnetic material;

[0034] [Figure 21] 21 is a perspective cross-sectional view of an exemplary embodiment of a rotor for use with the stator of FIG. 20. FIG.

[0035] [Figure 22] 1 is a perspective cross-sectional view of an exemplary embodiment of a motor incorporating a soft magnetic material; [Figure 23] 1 is a perspective cross-sectional view of an exemplary embodiment of a motor incorporating a soft magnetic material;

[0036] [Figure 24] 1 is a perspective cross-sectional view of an exemplary embodiment of a rotor in a motor including a soft magnetic material;

[0037] [Figure 25] 25 is a perspective cross-sectional view of an exemplary embodiment of a stator for use with the rotor of FIG. 24. FIG.

[0038] [Figure 26]26 is a perspective cross-sectional view of an assembly of the rotor of FIG. 24 and the stator of FIG. 25.

[0039] [Figure 27] 1 is a schematic cross-sectional view of an exemplary embodiment of a stator including a soft magnetic material.

[0040] [Figure 28] 1 is a perspective cross-sectional view of an exemplary embodiment of a motor incorporating a soft magnetic material; [Figure 29] 1 is a perspective cross-sectional view of an exemplary embodiment of a motor incorporating a soft magnetic material;

[0041] [Figure 30] FIG. 1 is a perspective cross-sectional view of an exemplary embodiment of a slotless stator including a soft magnetic material.

[0042] [Figure 31] FIG. 31 is a perspective cross-sectional exploded view of one exemplary embodiment of a rotor for use with the slotless stator of FIG. 30;

[0043] [Figure 32] FIG. 32 is a perspective cross-sectional view of an exemplary embodiment of a motor incorporating the slotless stator of FIG. 30 and the rotor of FIG. 31.

[0044] [Figure 33] FIG. 1 is a perspective cross-sectional view of another exemplary embodiment of a motor including a slotless stator and a soft magnetic material.

[0045] [Figure 34] FIG. 1 is a perspective cross-sectional view of one exemplary embodiment of a hybrid slotless motor.

[0046] [Figure 35A] FIG. 35 is a perspective view of the stator of the motor of FIG. 34. [Figure 35B] FIG. 35 is a perspective view of the stator of the motor of FIG. 34. [Figure 35C]FIG. 35 is a perspective view of the stator of the motor of FIG. 34.

[0047] [Figure 35D] FIG. 35 is a perspective view of the coil windings of the motor of FIG. 34.

[0048] [Figure 35E] FIG. 35 is a perspective view of a stator core of the motor of FIG. 34.

[0049] [Figure 36A-C] 36A-C are perspective and cross-sectional views of the rotor of the motor of FIG. [Figure 36D-E] 36D-E are a perspective view and a perspective cross-sectional view of the rotor of the motor of FIG.

[0050] [Figure 37] 35 is a schematic diagram of the motor of FIG. 34. [Figure 38] FIG. 35 is a perspective view of the coil windings of the motor of FIG. 34.

[0051] [Figure 39] FIG. 35 is a side cross-sectional view of a rotor pole of the motor of FIG. 34.

[0052] [Figure 40] 35 is a schematic diagram of the motor of FIG. 34 showing the coil windings potted on the stator.

[0053] [Figure 41] 1 is an electron microscope image of a cross section of a soft magnetic material.

[0054] [Figure 42] 1 is a graph showing an X-ray diffraction spectrum of a soft magnetic material.

[0055] [Figure 43] 1 is an image of the microstructure of thermally sprayed nickel-aluminum alloy particles.

[0056] [Figure 44A]1A and 1B are phase diagrams of an Fe-Al-Si alloy and an Fe-Al alloy, respectively. [Figure 44B] 1A and 1B are phase diagrams of an Fe-Al-Si alloy and an Fe-Al alloy, respectively.

[0057] [Figure 45] 1 is a schematic diagram of a mask / stencil system used to form a stator including soft magnetic material.

[0058] [Figure 46] 46A-C are schematic diagrams of an exemplary embodiment of a motor having a slotted stator. Detailed Description of the Embodiments

[0059] 1-6D, exemplary embodiments of soft magnetic materials for electrical devices and components thereof, as well as methods for manufacturing such materials and the electrical devices themselves, are described. The soft magnetic material is generally designated by the reference numeral 10. Electrical devices that can be used with such soft magnetic materials 10 include, but are not limited to, electric motors. Such electric motors can be used in, for example, robotic applications, industrial automation, HVAC systems, electrical appliances, medical devices, military and space exploration applications, and the like. Components that can be used with such materials include, but are not limited to, electric motor winding cores and other suitable soft magnetic cores. While the invention will be described with reference to the embodiments shown in the drawings, it should be understood that the invention may be embodied in various alternative embodiments. Furthermore, any suitable size, shape, or type of material or element may be used.

[0060] With particular reference to FIG. 1 , soft magnetic material 10 has a microstructure with favorable softness and mechanical strength and is formed as a bulk material by depositing alloying elements in a reactive atmosphere to produce agglomerates of small microdomains 12 with high magnetic permeability and low coercivity, separated by insulating boundaries 14 that limit electrical conductivity. The use of such bulk materials in electrical devices is expected to improve performance and efficiency. For example, the use of soft magnetic material 10 in a motor core can provide an efficient magnetic path while minimizing losses associated with eddy currents induced in the core due to rapidly changing magnetic fields when the motor containing the motor core rotates. This substantially eliminates the design constraints typically associated with anisotropic laminated cores in conventional motors.

[0061] 2A and 2B, a schematic diagram of one exemplary embodiment of a deposition process for obtaining a soft magnetic material 10 is generally designated by the reference numeral 20 and hereinafter referred to as "deposition process 20." As shown in FIG. 2A of deposition process 20, particles 22 of alloying elements are deposited onto a substrate 24 via a single-step net-shape manufacturing process based on a metal spray process. To obtain a soft magnetic material 10 having a desired microstructure, various parameters related to the state of the alloy used are defined. Regarding the first exemplary parameter, the temperature of particles 22 is below the melting point of the material of particles 22, yet high enough to soften the material. In this way, particles 22 remain substantially solid and maintain their overall acicularity upon impact with the surface of substrate 24. More specifically, particles 22 are in a semi-molten state during flight. Regarding the second exemplary parameter, oxidation of the particles 22 is limited during the deposition process 20, so that the particles 22 remain substantially metallic and maintain their mechanical strength and magnetic properties. Regarding the third parameter, the velocity of the particles 22 during the deposition process 20 may be equal to or greater than approximately a minimum flight speed that ensures the particles 22 adhere to previously deposited particles, thereby depositing a mass of alloy to form a soft magnetic material 10 with sufficient mechanical strength, as shown in FIG. 2B. This parameter (as well as others) can be achieved by selecting the particle size range, chemical composition, and various process parameters of the deposition process 20. The system used to perform the deposition process 20 may be a high-velocity air-fuel (HVAF) system, a high-velocity oxygen-fuel (HVOF) system, or a plasma spray system.

[0062] Commercially available alloying elements may be used for the particles 22. The alloying elements may be any suitable aluminum-based powder (e.g., FE-125-27), such as those available from Praxair Engineering, Inc., Indianapolis, Indiana. In one exemplary embodiment, the alloy may have a composition of 89% Fe-10% Al-0.25% C (all percentages by weight). Such an alloy has a melting point of approximately 1450°C, making it suitable for use in HVAF systems where the temperature of the carrier gas used to atomize the alloy is between approximately 900°C and approximately 1200°C. Such an alloy is also suitable for HVOF systems operating at temperatures below approximately 1400°C. While the exemplary embodiment described herein is directed to an alloy having a composition of 89% Fe-10% Al-0.25% C, other exemplary embodiments may employ alloys of other compositions.

[0063] The alloy particles are generally spherical and capable of being atomized, allowing them to flow freely without agglomeration during deposition process 20, making them suitable for use as particles 22 in HVAF or HVOF systems. The selection of alloy particle size affects the particle velocity as well as the temperature of the alloy particles during deposition process 20. In one exemplary embodiment using HVOF deposition, alloy particles in the range of about 25 microns to about 45 microns can achieve the desired particle temperature and particle velocity.

[0064] In a deposition process 20 using an HVAF system, the desired microstructure of the resulting soft magnetic material 10 can be achieved as a bulk material by depositing successive thin coatings. HVAF systems are capable of using a focused particle beam and can have deposition rates of approximately 80% or greater. As can be seen in FIG. 3A, the cross-section of the microstructure of the soft magnetic material 10 clearly shows the microdomains 12, and the larger grains of the soft magnetic material 10 are clearly shown by the boundaries 14 while maintaining their overall acicular ratio.

[0065] The deposition process 20 using an HVOF system may operate in a temperature range of about 1400°C to about 1600°C to produce the desired microstructure of the soft magnetic material 10, as shown in Figure 3B. In an HVOF system, the soft magnetic material 10 may be produced at a low firing temperature setpoint to produce a thin coating of deposited material. However, a lower firing temperature setpoint may result in particles 22 impacting the substrate 24 at a lower velocity, which may result in a deposition rate below 50%.

[0066] 3C, the desired microstructure of the soft magnetic material 10 may be produced using a low-energy plasma spray system. As can be seen, the distinction between micro-domains 12 and larger grains may not be as obvious as in soft magnetic materials 10 produced using HVAF or HVOF systems.

[0067] In a deposition process 20 using any of the exemplary systems described above, the soft magnetic material 10 is formed by thermally spraying the alloy as particles 22 onto a substrate 24. The sprayed particles 22 form a dense, dense solid layer of material comprised of dense microdomains 12 separated by electrically insulating insulating boundaries 14. The sprayed particles 22 forming the solid layer of material may then be heat treated at a temperature of about 1925°F for about four hours, then slowly cooled to about 900°F (at a rate of about 100°F per hour over about ten hours), and finally air cooled to about room temperature.

[0068] The alloying elements may be defined by particles 22 in any of several different forms. Regardless of their form, the alloying elements (impinging particles) contain iron and aluminum, with the aluminum oxidizing to form a protective alumina layer (i.e., aluminum oxide) on the iron. The particle core may be completely covered by the protective alumina layer, or the protective layer may have defects or blockages that prevent the particle core from being completely covered. Because alumina is more stable than any iron oxide, optimizing the aluminum concentration of the alloy creates a sufficient amount of alumina that is free (or substantially free) of iron oxide. In one example embodiment, the alloy is an Fe-Al alloy containing 89% Fe, 10% Al, and 0.25% C. The alloy is not limited in this regard, and any other suitable material may be used.

[0069] 4A-4C, using the deposition process 20, the soft magnetic material 10 can be used to create any suitable structure that can be machined to create an ingot 30 (FIG. 4A), a cylinder 32 (FIG. 4B), or a ring-shaped component 34 (FIG. 4C). The structure (e.g., cylinder 32, ring-shaped component, etc.) produced by the deposition process 20 can be used as an element in the manufacture of a motor or motor component.

[0070] As shown in FIG. 5A, in one exemplary form of the particles 22 used to form the soft magnetic material 10, the particles 22 have a uniform composition of Fe—Al alloy 40. The aluminum on the surface of the particles 22 reacts with oxygen in the surrounding environment (which may be air or oxygen-enriched air) to form alumina, producing Fe—Al alloy particles with a thin alumina layer 42 on their outer surfaces. The aluminum concentration of the Fe—Al alloy 40 is selected to facilitate the formation of a continuous alumina layer 42 while preventing or at least minimizing the formation of iron oxide. Because the rate of oxidation increases with temperature, the temperature of the particles may be increased to increase the oxidation reaction rate. The particle temperature is also increased to a temperature high enough to soften the particles and achieve the deformation necessary to form a dense structure. To form a dense solid, the particles are accelerated to a sufficient velocity before impacting the surface. In some embodiments, silicon may be added as an alloying element. In some compositions, the addition of silicon can improve magnetic properties without interfering with the formation of alumina.

[0071] In another exemplary form of particle 22, as shown in FIG. 5B, the particle 22 may be defined by a concentration gradient from the Fe—Al alloy 40 to the surface. The aluminum at the surface is formed by the preferred aluminum concentration of the Fe—Al alloy. However, aluminum reduces the saturation magnetic flux density of the iron. To maximize the saturation magnetic flux density, the resulting particle has a pure iron core 44 with an increasing aluminum concentration 46 from the iron core 44 toward the particle surface 48. This form is achieved by depositing an aluminum layer on the particle and heat-treating it so that the aluminum diffuses into the particle, forming an alloy with a varying aluminum concentration 46. The aluminum concentration is selected to favor the formation of a continuous alumina layer 42 along the surface 48 without (at least substantially) forming iron oxide, and the particle is heat-treated in an inert environment to prevent oxidation of the aluminum. The ambient environment can be air or oxygen-enriched air. Since the rate of oxidation increases with temperature, the temperature of the alloy particles can be increased to increase the oxidation reaction rate. As with the previous embodiment, to form a dense solid, the particles are accelerated to a sufficient velocity before impacting the surface. The particle temperature is also raised high enough to soften the alloy material and obtain the deformation necessary to form a dense structure. Additionally, silicon may be added as an alloying element to improve magnetic properties, for example, without interfering with the formation of alumina.

[0072] As shown in FIG. 5C, another exemplary form of particle 22 may comprise an iron or iron alloy base particle 50 encapsulated in an alumina layer 42. These alumina-coated iron (or iron alloy) particles may be obtained by an atomic layer deposition (ALD) process, i.e., by depositing a thin aluminum layer, exposing it to oxygen to oxidize it, and then depositing and oxidizing subsequent layers. However, the deposition process is not limited to ALD; any suitable process may be used to form an alumina layer on the iron or iron alloy particles. Several such layers are deposited to achieve the desired thickness of the alumina layer 42. The base particle 50 may be pure iron or an iron alloy, such as iron-cobalt, iron-nickel, or iron-silicon, which enhances magnetic properties. To form a dense solid, the particles are accelerated to a sufficient velocity before impacting a surface. During the deposition process 20, the particle temperature is raised to a temperature high enough to soften the particles and induce the particle deformation necessary to form a dense structure. As with other embodiments, silicon may be added as an alloying element to improve magnetic properties while preventing or minimizing the formation of alumina. Adding 1% silicon as an alloying element to an Fe-Al alloy with approximately 10 wt.% aluminum results in a raw material with minimal carbon content (and potentially larger grain size).

[0073] As shown in FIG. 5D, in another exemplary form of particle 22, the base particle 50 includes an iron or iron alloy core that may be encapsulated in aluminum, which oxidizes during the deposition process to form the alumina layer 42. The base particle 50 can be, for example, pure iron or an iron alloy (e.g., iron-cobalt, iron-nickel, iron-silicon, etc.) that enhances magnetic properties. The ambient environment can be air, oxygen-enriched air, or an environment with a tightly controlled oxygen environment. As with the previous embodiment, the particles are accelerated to a sufficient velocity before impacting the surface to form a dense solid. During the deposition process 20, the particle temperature is increased to a temperature high enough to soften the particles and obtain the particle deformation necessary to form a dense structure. As with the previous embodiment, silicon may be added as an alloying element to improve magnetic properties while preventing or minimizing alumina formation.

[0074] The electromagnetic properties of the soft magnetic material 10 formed from any of the above particle 22 morphologies include, but are not limited to, saturation magnetic flux density, permeability, energy loss due to hysteresis, and energy loss due to eddy currents. These desired electromagnetic properties are achieved by a microstructure containing a high density of microdomains with suitable magnetic properties, each surrounded by a thin insulating boundary. The magnetic properties of the microdomains and the insulating properties of the boundaries are a function of one or more physical and chemical properties, such as the alloy's composition, lattice structure, oxidation thermodynamics, and reaction kinetics.

[0075] In terms of lattice structure, the alloy containing 89% Fe-10% Al has the same body-centered cubic (BCC) structure as iron. This lattice structure is associated with high magnetic permeability and favorable magnetic properties. Furthermore, in the presence of 0.25% carbon, the alloy maintains its BCC structure up to temperatures of 1000°C. Any face-centered cubic and martensitic structures present in the solid can be converted to a BCC structure by heat treatment. The atomic fraction of aluminum in the alloy is approximately 20%, and therefore, the alloy has a saturation magnetic flux density approximately 20% lower than pure iron. The alloy is also known to have a higher electrical resistivity than pure iron, resulting in lower eddy current losses.

[0076] Carbon in the range of about 0.25% can facilitate the atomization process during powder production. At temperatures below about 1000°C, carbon exists as precipitated carbides that can affect magnetic properties, such as reducing initial permeability and increasing hysteresis loss.

[0077] Alumina is the preferred stable oxide formed when alloy particles are exposed to an oxidizing environment in the temperature range of approximately 1000°C to approximately 1500°C. The rate of formation and estimated thickness of this oxide layer are determined by the oxidation kinetics of the alloy particles in the deposition environment. Aluminum element forms an oxide layer 1 to 2 nanometers (nm) thick, effectively preventing further oxidation. Additionally, oxidation kinetics simulations using a software simulation package determined that pure iron particles 25 to 40 microns in size and at temperatures of approximately 1500°C will form an oxide layer 500 nm thick during their flight period (estimated to be approximately 0.001 seconds using the deposition process 20 by any of the HVAF, HVOF, or plasma spray systems described herein). Therefore, the estimated thickness of the oxide layer formed around each particle is approximately 1 nm to approximately 500 nm.

[0078] Referring now to Figures 6A-6D, in all embodiments, it is desirable for the magnetic properties of the thermally sprayed sample to be isotropic. Isotropy allows for the expectation of three-dimensional magnetic flux flow in motors using the material. The magnetic properties measurable in the described embodiment can be measured along the circumferential direction of a ring-shaped sample (as shown in Figure 6A), in accordance with the ASTM A773 standard. Even if measurements along the other two orthogonal directions (axial and radial) are not possible, the degree of isotropy of the material can be determined by the microstructure of the sample cross-section in three orthogonal planes corresponding to the XZ, YZ, and XY planes, as shown in Figures 6B, 6C, and 6D, respectively. Even if a small region extends somewhat along the circumferential direction, the shape exhibits a high degree of isotropy because this circumferential direction is perpendicular to the spraying direction.

[0079] 7-40 and 46, there are shown various exemplary embodiments of motors incorporating the soft magnetic material 10. The motors described are intended to be driven as three-phase brushless motors with sinusoidal commutation using position feedback from a high-resolution rotary encoder.

[0080] 7, a permanent magnet motor with magnetic flux flow along a plane perpendicular to the motor's axis of rotation is shown generally at 100. Motor 100 has a rotor 102 made of magnetic steel (or other suitable magnetic material) and rotatably mounted within a stator 106. Magnets 104 are disposed on the radially outer surface of rotor 102. Stator 106 has a laminated steel core defining stator poles 108 along the inner edge of stator 106, and a winding or coil 110 disposed at each stator pole 108. Motor 100 may include a soft magnetic material 100.

[0081] Referring to FIG. 8 , the soft magnetic material 10 described herein may be incorporated into an electric motor (e.g., as a stator, or at least as part of a stator). One exemplary embodiment of a flux motor incorporating the soft magnetic material 10 is generally designated by the reference numeral 200 and will hereinafter be referred to as “motor 200.” Motor 200 is a three-dimensional flux motor having a rotor 202 rotatably mounted within a stator 206. Rotor 202 may be configured as a shaft. The radially outer cylindrical surfaces of rotor 202 define rotor poles 212, and the inner edges of stator 206 define stator poles 208. Stator 206 includes a plurality of slots along stator poles 208 that define cores around which individual windings of coils 210 are wound. However, in an alternative configuration, stator poles 208 may have coils formed as distributed windings.

[0082] In motor 200, magnets 204 are arranged on rotor poles 212. The rotor poles 212 and stator poles 208, combined with the shape of magnets 204, direct magnetic flux between the rotor and stator outwardly of one plane in three-dimensional space. Magnets 204 may have a radially outer cylindrical surface that abuts two conical surfaces and terminates in two cylindrical surfaces of a smaller diameter. Magnets 204 are shown as unitary in shape. However, in other embodiments, the magnets may include individual segments that define their shape. Similarly, stator poles 208 are configured to approximate a Y-shaped cross section that defines a surface corresponding to the opposing surface of magnet 204. Furthermore, the Y-shaped cross section allows magnetic flux to flow within the stator along one or more of the radial, axial, and / or circumferential directions of the motor.

[0083] Conical air gaps 214 between the magnets 204 and the stator poles 208 allow magnetic flux to flow radially, axially, and circumferentially around the motor 200. Because the rotor poles 212 extend toward the stator poles 208, and the stator poles 208 extend toward the rotor poles 212, the conical air gaps 214 between the rotor poles 212 and the stator poles 208 define a conical torque-producing area, resulting in a higher torque capacity compared to the permanent magnet motor 100 shown in Figure 7. The larger conical torque-producing area defined by the conical air gaps 214 more than compensates for the slightly smaller torque-producing radius and coil spacing.

[0084] The rotor 202 and / or stator 206 (or at least the core of the stator 206) may be made from a soft magnetic material 10 having high saturation flux density, permeability, and low energy losses due to hysteresis and eddy currents. A microstructure with high density microdomains with favorable magnetic properties, each surrounded by a thin insulating boundary, can achieve the desired electromagnetic properties and facilitate the use of three-dimensional magnetic flux paths, as opposed to conventional motors that utilize one-dimensional magnetic flux paths, such as a single in-plane path. Such materials may also be used in the embodiments described further.

[0085] Referring now to FIG. 9 , a variant of a cylindrical air-gap 3D flux motor is generally designated 300. In motor 300, rotor 312 is rotatably mounted within stator 306 such that rotor poles 312 face stator poles 308. Stator 306 (or at least its core) may include soft magnetic material 10. Magnets 304 are disposed on rotor poles 312. The torque-producing region defined by conical air gaps 314 between magnets 304 of rotor poles 312 and stator poles 308 is cylindrical and extends only in the axial direction. The outer wall 307 of stator 306 also extends in the axial direction. This extension of outer wall 307 allows for the use of a thinner-walled stator without sacrificing the cross-sectional area of ​​the stator wall available for magnetic flux flow. This extension of outer wall 307 also provides more space for coils 310. The conical air gap 314 is cylindrical in shape, but the magnets 304 located at the rotor poles 312 and adjacent to the stator poles 308 are elongated, so that the magnetic flux is directed in more than one plane, thereby creating a three-dimensional magnetic flux pattern.

[0086] 10A and 10B, another exemplary embodiment of a flux motor is generally designated 400. Similar to the previously described embodiments, motor 400 includes a rotor 402 rotatably disposed within a stator 406. Stator 406 includes stator poles 408 and coils 410, with both coils 410 and stator poles 408 tapering radially to maximize the cross-sectional area of ​​each stator pole 408. More specifically, the circumferential dimension of each coil 410 tapers along interface 416 to increase with radius, while the axial dimension of each stator pole 408 tapers along interface 416 to decrease with radius. While the examples described herein are directed to permanent magnet motors, in other aspects, any of the described embodiments may be applied to variable reluctance motors (e.g., non-permanent magnet poles) or any other suitable motor. The combination of tapered stator poles 408 and extended surface stator poles facilitates the formation of magnetic flux on more than one surface between stator 406 and rotor 402 .

[0087] 10B, one exemplary embodiment of a stator pole 408 exhibiting a two-dimensional tapered configuration is shown. As can be seen, the axial dimension of the stator pole 408 decreases from height H1 to height H2 as the radius increases. Additionally, the circumferential width of the stator pole 408 increases radially from width W1 to width W2 to maintain the "tooth area" of the cross-section of the stator pole 408. In one exemplary embodiment, the cross-sectional area of ​​the tapered portion of the stator pole 408 may be maintained constant so that the flux density within the stator pole 408 is maintained throughout the cross-section.

[0088] Referring now to FIG. 11 , another exemplary motor variant is generally designated 500. In motor 500, rotor 502 and stator 506 can be assembled axially. This embodiment is similar to the embodiment of FIGS. 10A and 10B, except that only one end of rotor 502 and stator 506 is tapered (along surface 520), while the other end is straight or cylindrical (along surface 522). The embodiment shown in FIG. 11 allows for assembly of rotor 502 to stator 506 along the axial direction. Alternate embodiments may combine any of the aspects of the previously described embodiments in any suitable combination.

[0089] Referring now to FIG. 12 , motor 600 includes rotor 602 and split stator 606, which can be easily assembled around rotor 602, either before or after winding. As shown, motor 600 may have features similar to those illustrated above. However, split stator 606 allows rotor 602 to be constructed as a single unit, with first stator section 607 and second stator section 609 assembled circumferentially around rotor 602 and joined by split line 611 in the plane along which magnetic flux is directed. In the portion of split stator 606 opposite split line 611, magnetic flux between rotor 602 and split stator 606 is directed in a direction that includes more than one plane, resulting in a three-dimensional magnetic flux pattern.

[0090] 13 , another exemplary embodiment of a motor 700 includes a rotor 702 and a split stator 706, where the split stator 706 is divided into three layers (an inner portion 707, a center portion 709, and an outer portion 713) around which coils 710 are wound. The center portion 709 may be made of a different material (e.g., laminated steel) than the inner portion 707 and the outer portion 713. In the center portion 709, the magnetic flux flow may be substantially flat. The inner portion 707 and the outer portion 713 may be made of a material that facilitates three-dimensional magnetic flux flow.

[0091] As shown in FIGS. 14A and 14B , another exemplary embodiment of a motor 800 includes a split concave rotor 802 having first and second rotor sections 803 and 805, each with a corresponding magnet 807, 809, which are axially assembled to a stator 806. The split configuration of the rotor 802 allows the stator 806 to be constructed as a single unit, for example, by winding a coil 810 and then assembling the first and second rotor sections 803 and 805 of the rotor 802 around the stator 806. A split line 817 exists in the plane along which the magnetic flux is directed. In the portion of the rotor 802 opposite the split line 817, the magnetic flux of the rotor 802 and stator 806 is directed in a direction that includes more than one plane, thereby forming a three-dimensional magnetic flux pattern. Alternatively, the stator 806 may be divided into two or more layers. For example, in a three-section stator 806, the center section may be made of laminated steel, as previously described. The motor 800 allows for magnetic flux flow along the radial, axial, and circumferential directions. The motor 800 has radially extending stator poles 808 and rotor poles 812, which increase the conical torque-producing air-gap area and provide higher torque capacity compared to conventional motors. Here, the larger torque-producing area more than compensates for a somewhat smaller torque-producing radius and coil spacing. As with each of the previously described embodiments, the rotor 802 and / or stator 806 may be made of a soft magnetic material 10 having high saturation flux density, permeability, and low energy losses due to hysteresis and eddy currents. The microstructure of the soft magnetic material 10, which includes a high density of minute domains having suitable magnetic properties, each surrounded by a thin insulating boundary, provides the desired electromagnetic properties and facilitates the use of three-dimensional magnetic flux paths, as opposed to conventional motors that utilize one-dimensional magnetic flux paths, such as a single in-plane path. Further described embodiments may utilize such materials as well. Alternative embodiments may combine any of the aspects of the previously described embodiments in any suitable combination.

[0092] Referring again to Figures 14A and 14B, magnets 807, 809 are located on rotor poles 812, with their two radially outer cylindrical surfaces abutting two conical surfaces on rotor sections 803, 805, respectively, and terminating in two cylindrical surfaces of smaller diameter. While magnets 807, 809 are shown as single pieces in this configuration, they may be comprised of separate segments forming the same shape. Stator poles 808 have similarly shaped faces corresponding to the opposing faces of magnets 803, 805. The pole shape, combined with the magnet shape, directs magnetic flux between rotor 802 and stator 806 outwardly of a single plane in three-dimensional space. Coils 810 are shown as individual windings wrapped around individual stator poles 808. In another embodiment, coils 810 may include distributed windings.

[0093] 15A and 15B, a motor 900 is shown having a split concave rotor 902 and a split stator 906. The split concave rotor 902 has a first rotor section 903 and a second rotor section 905, and the split stator 906 has a first stator section 907 and a second stator section 909. In contrast to the split stator 706 shown in FIG. 13, the first stator section 907 and the second stator section 909 each have their own coils 910, 911 that can be wound onto the first stator section 907 and the second stator section 909, respectively, prior to assembling the rotor 902 and stator 906. The split concave rotor 902 allows for pre-assembly and winding of the split stator 906, e.g., by assembling the first rotor section 903 and the second rotor section 905 around the already wound stator 906. The stator 906 is split to allow magnetic flux to flow radially, axially, and circumferentially through the motor 900. The elongated rotor poles 912 and stator poles 908 in the motor 900 increase the conical torque-producing air gap area, resulting in higher torque capacity compared to conventional motors. The larger torque-producing area more than compensates for a slightly smaller torque-producing radius and coil spacing. As with each of the described embodiments, the rotor 902 and / or stator 906 may be fabricated from a soft magnetic material 10 having high saturation flux density, permeability, and low energy losses due to hysteresis and eddy currents. The microstructure of the soft magnetic material 10, which includes a high density of minute domains having suitable magnetic properties, each surrounded by a thin insulating boundary, provides the desired electromagnetic properties and facilitates the use of three-dimensional magnetic flux paths, as opposed to conventional motors that utilize one-dimensional magnetic flux paths, such as a single in-plane path. Further described embodiments may utilize such materials as well. Alternative embodiments may combine any of the aspects of the previously described embodiments in any suitable combination.

[0094] Also shown in Figures 15A and 15B, magnets 930, 932 are located on rotor poles 912, with their two radially outer cylindrical surfaces abutting the two conical surfaces of rotor sections 903, 905, respectively, and terminating in two cylindrical surfaces with smaller diameters. While magnets 930, 932 are shown as single pieces in this configuration, they may be comprised of separate segments forming the same shape. Similarly, stator poles 908 are shaped poles with faces corresponding to the opposing faces of magnets 930, 932. The pole shape, combined with the magnet shape, directs magnetic flux between rotor 902 and stator 906 outwardly of a single plane in three-dimensional space. Coils 910 are shown as individual windings wrapped around individual stator poles 908. Alternatively, coils 910 may include distributed windings.

[0095] 16A and 16B, a motor 1000 is shown having a split convex rotor 1002 axially assembled with a split stator 1006. The split convex rotor 1002 includes a first rotor section 1003 and a second rotor section 1005. In an alternative embodiment, the rotor 1002 may not be split, but instead may include a single piece. The split stator 1006 includes a first stator section 1007 and a second stator section 1009, with each section of the stator having its own coil set 1010, 1011. Each stator section 1007, 1009 may be wound prior to assembly. The stator 1006 is split to allow the motor 1000 to pass magnetic flux radially, axially, and circumferentially. The elongated rotor poles 1012 and stator poles 1008 in the motor 1000 increase the conical torque-producing air-gap area, resulting in higher torque capacity compared to conventional motors. The larger torque-producing area more than compensates for a slightly smaller torque-producing radius and coil spacing. As with each of the described embodiments, the rotor 1002 and / or stator 1006 may be fabricated from a soft magnetic material 10 having high saturation flux density, permeability, and low energy losses due to hysteresis and eddy currents. The microstructure of the soft magnetic material 10, which includes highly dense microdomains with favorable magnetic properties and each surrounded by a thin insulating boundary, achieves the desired electromagnetic characteristics and facilitates the use of three-dimensional magnetic flux paths, as opposed to conventional motors that utilize one-dimensional magnetic flux paths, such as a single in-plane path. Such materials may also be used in further described embodiments. In alternative embodiments, any of the aspects of the previously described embodiments may be combined in any suitable combination.

[0096] Referring again to Figures 16A and 16B, magnets 1030, 1032 are located on rotor poles 1012, with their two radially outer cylindrical surfaces abutting two conical surfaces on rotor sections 1003, 1005, respectively, and terminating in two cylindrical surfaces of smaller diameter. While magnets 1030, 1032 are shown as single pieces in this configuration, they may be comprised of separate segments forming the same shape. Similarly, stator poles 1008 are shaped poles with faces corresponding to the opposing faces of magnets 1030, 1032. The pole shape, combined with the magnet shape, directs magnetic flux between rotor 1002 and stator 1006 outwardly of a single plane in three-dimensional space. Coils 1010, 1011 are shown as separate windings wrapped around individual stator poles 1008. Alternatively, coils 1010, 1011 may include distributed windings.

[0097] 17A-17C, schematic diagrams of stator cross sections are shown. FIG. 17A shows a cross section of a motor coil 110, stator poles 108, and stator wall 140. The cross-sectional area of ​​the stator is indicated by height 142 and width 144, where the width of the coil 110 may be 150 and the axial height of the pole may be 152. The stator poles 108 may be made of laminated steel suitable for motor stators. As will be described later with respect to the area defined by width 144 and height 142, the use of soft magnetic materials described herein (as shown in FIGS. 17B and 17C) allows for three-dimensional magnetic flux flow within the stator, allowing for more efficient use of the cross section. For example, in FIG. 17B , coil 1110, stator pole 1108, and stator wall 1140 are shown, but width 1176 may be reduced and axial height 1178 of stator wall 1140 may be increased to increase the cross-sectional area and length 1180 of coil 1108. The axial height of the pole is indicated by 1190. Further by way of example, in FIG. 17C , coil 1210, stator pole 1208, and stator wall 1240 are shown, the cross-sectional area of ​​the stator pole may be increased by thinning stator wall 1240 and increasing its axial height, as in FIG. 17B , or coil 1210 may be made longer and thinner to maintain the same cross-sectional area as the coil in FIG. 17A . Here, pole axial height 1290 may be greater than pole axial height 1190 shown in FIG. 17B .

[0098] Referring now to Figures 18A-18C, a cross section of another exemplary embodiment of a motor 1300 includes a convex rotor 1302 and a split stator 1306. Each half of the stator 1306 has its own winding set. While a single rotor 1302 and stator 1306 are shown, in other embodiments, multiple rotors and / or stators may be stacked. The illustrated embodiment includes a triangular cross section, which may be a single triangular cross section or multiple cross sections, such as concave and convex. In still other embodiments, the motor 1300 may include a concave rotor or a rotor of any suitable shape. Each of the stator sections 1307, 1309 may be wound prior to assembly. The stator sections 1307, 1309 include a gradient winding 1310 wound around tapered poles 1308. Magnetic flux is directed from pole to pole by stator walls 1340, which have triangular cross sections at the upper and lower corners of the stator 1306. The side cross-sectional view of FIG. 18A shows the stator poles 1308 with a tapered configuration, increasing in cross section toward the axial rotor 1302. The top cross-sectional view of FIG. 18B shows the stator poles 1306 with a tapered configuration, decreasing in cross section toward the axial rotor. Note that tapering may be combined to maintain the cross-sectional area of ​​the stator poles 1306. The segmented configuration of the stator 1306 allows for pre-assembly and winding of the stator 1306, for example, assembling two stator sections 1307, 1309 around the rotor 1302 after winding. In the motor 1300 shown with a segmented stator 1306, magnetic flux flows along the radial, axial, and circumferential directions. As previously described in other exemplary embodiments, the motor 1300 has elongated rotor and stator poles, which increases the conical torque-producing air-gap area and results in higher torque capacity compared to conventional motors. The larger torque-producing area more than compensates for a slightly smaller torque-producing radius and coil spacing. As with each of the described embodiments, the rotor 1302 and / or stator 1306 may be made from a soft magnetic material 10 having high saturation flux density, permeability, and low energy losses due to hysteresis and eddy currents.The microstructure of the soft magnetic material 10, which includes a high density of minute domains having suitable magnetic properties, each surrounded by a thin insulating boundary, provides the desired electromagnetic properties and facilitates the use of three-dimensional magnetic flux paths, as opposed to conventional motors that utilize one-dimensional magnetic flux paths, such as a single in-plane path. Further described embodiments may utilize such materials as well. Alternative embodiments may combine any of the aspects of the previously described embodiments in any suitable combination.

[0099] 18A and 18C, magnets 1340, 1342 are located on rotor poles 1312, with their two radially outer cylindrical surfaces abutting two conical surfaces on rotor sections 1307, 1309, respectively, and terminating in two cylindrical surfaces of smaller diameter. While magnets 1340, 1342 are shown as single pieces in this configuration, they may be comprised of separate segments that define the shape. Similarly, stator poles 1308 are shaped poles with faces that correspond to the opposing faces of magnets 1340, 1342. The pole shape, combined with the magnet shape, directs magnetic flux between rotor 1302 and stator 1306 outwardly of a single plane in three-dimensional space. Coils 1310 are shown as individual windings wrapped around individual stator poles 1308. In another embodiment, coils 1310 may include distributed windings.

[0100] Referring now to FIG. 19 , a cross section of a motor 1400 is shown having a convex rotor 1402 and a stator 1406. While a single rotor 1402 and a single stator 1406 are shown, in other embodiments, multiple rotors and / or stators may be laminated. The stator 1406 has angled windings 1410 wound around tapered poles 1408. Magnetic flux is directed from pole to pole by stator walls 1440, which have a triangular cross section at the upper corners of the stator 1406. In the embodiment shown, the width of the triangular cross section is wider at the ends of the poles 1408 to provide additional winding area for the windings 1410. Similarly, the faces of the poles 1408 facing the magnets of the rotor 1402 may be elongated as shown or to provide additional winding area for the windings 1410. In other embodiments, any of the aspects of the previously described embodiments may be combined in any suitable combination.

[0101] 20 and 21, isometric cross-sectional views of the stator 1506 and rotor 1502, respectively, are shown. In the exemplary embodiment shown, the inwardly angled stator teeth 1550 are angled perpendicular to the orientation of the outwardly angled magnets 1540. This arrangement utilizes available space to increase the cross-sectional area for magnetic flux flow. The teeth 1550 have upper and lower portions 1552 and 1554 that overlap the coils 1510 so that magnetic flux flows across the entire cross section of each stator tooth 1550. The portions similarly overlap the coils 1510 of the stator ring 1556 so that magnetic flux flows across the entire cross section of the stator ring 1556 from tooth to tooth of the stator 1506. While individual windings are shown per pole, distributed windings may be provided instead.

[0102] 22 and 23, an assembled rotor 1602 and stator 1606 arrangement is shown. In one exemplary embodiment, a single stator 1606 and rotor 1602 may be provided. As seen in FIG. 22, the stator 1606 may include a first stator section 1607 and a second stator section 1609, and the rotor 1602 may include a first rotor section 1603 and a second rotor section 1605. The stator 1606 and rotor 1602 may be assembled such that the first and second stator sections form two triangular cross sections that meet radially at a narrow portion. As seen in Figure 23, the first stator section 1607 and the second stator section 1609 may be alternately assembled with the first rotor section 1603 and the second rotor section 1605 so that the stator sections form two triangular cross sections that meet radially at their widest points. Alternatively, any suitable combination may be provided. The stator teeth are convex and the rotor teeth are concave.

[0103] In the exemplary embodiments of Figures 20-23, the tooth cross-sectional area and the coil cross-sectional area may not be independently determined. As a result, a larger tooth cross-section can be achieved by reducing the coil cross-section, or conversely, a larger tooth cross-section can be achieved by reducing the tooth cross-section. As will be described later, in the embodiments of Figures 24-29, the tooth cross-sections can be independently varied to achieve an optimal design. However, this flexibility comes at the expense of a smaller magnet area. However, the embodiment shown in Figure 20 is a special case of the embodiment shown in Figure 27, such as when a = 0 in Figure 27. For example, setting a = 0 and b = c results in the embodiments of Figures 20-23.

[0104] 24 and 25, isometric cross-sectional views of rotor 1702 and stator 1706, respectively, are shown. Referring further to FIG. 26, rotor 1702 and stator 1706 are shown assembled. As shown in FIG. 26, a single stator 1706 and a single rotor 1702 may be provided. As shown in FIG. 28, stator 1706 may include first stator section 1707 and second stator section 1709, either of which may be assembled with rotor 1702, which includes first rotor section 1703 and second rotor section 1705, to form two cross sections that join radially at the widest portions of the cross sections.

[0105] As shown in FIG. 29, the stator 1806 may include a first stator section 1807 and a second stator section 1809, either of which may be assembled with a rotor 1802 including a first rotor section 1803 and a second rotor section 1805 to form two cross sections that join radially at the wide portions of the cross sections.

[0106] Referring back to FIG. 27 , a cross-sectional view of a stator pole is shown with variable parameters indicated. In the illustrated embodiment, the stator tooth 1550 has faces 1562, 1564, and 1566 that are oriented at various angles relative to the perpendicular orientation of the magnet. This arrangement utilizes available space to increase the cross-sectional area for magnetic flux flow. The tooth 1550 has an upper portion 1552 and a lower portion 1554 that overlap the coil 1510 to allow magnetic flux to flow across the entire cross-section of the stator tooth 1550. While separate windings are shown for each pole, distributed windings may alternatively be provided. The stator tooth 1550 has a portion 1570 whose cross-section varies to optimize the coil 1510, as indicated by the measured parameters a, b, c, and d. Alternatively, any suitable combination may be provided.

[0107] 30 and 31, isometric cross-sectional views of a stator 1906 and a rotor 1902 are shown, respectively. The exemplary embodiment shown includes a slotless stator design in which the stator 1906 has a soft magnetic core 1912 and potted windings 1914. The soft magnetic core 1912 is defined directly on the surface of the stator 1906 (thus avoiding the use of slots) and may include soft magnetic material 10 as described above. As shown, the rotor 1902 may be the two-piece rotor shown in FIGS. 31 and 32 (including a first rotor section 1903 and a second rotor section 1905). Alternatively, a motor may be created with just half of the rotor 1902 and stator 1906.

[0108] Referring now to FIG. 33 , another exemplary embodiment of a slotless motor is generally designated 2000. Slotless motor 2000 includes a rotor 2002 rotatably mounted within a slotless stator 2006. Rotor 2002 includes a first rotor section 2003 and a second rotor section 2005, which are symmetrical to each other. Slotless stator 2006 includes a wall 2007 and a base 2009 that form a continuous section having a constant cross section. Magnets 2014 are mounted between rotor 2002 and slotless stator 2006. Windings as coils 2010 are self-supporting and evenly distributed on the inwardly facing surface around slotless stator 2006, forming a V-shaped cross section in horizontal view. Motor 2000 is further described in Example 3 below.

[0109] 34-40, a slotless, brushless, permanent magnet motor that may incorporate the soft magnetic materials described herein is generally designated 2100. Motor 2100 is a hybrid motor. As can be seen in FIGS. 34 and 37, the air gap cross section 2110 is V-shaped and may include a spacer 2112.

[0110] As shown in FIGS. 35A-35E, the stator assembly of the motor 2100 is generally designated 2120. As can be seen in FIG. 35C, the stator assembly 2120 has notches 2135 in its rear wall 2130 (which follows the contours of the coils) to accommodate cooling lines and the like. The notches 2135 may have any suitable shape and may be provided to conserve material. The notches 2135 may be shaped to create a uniform magnetic flux distribution in one or more portions of the stator, such as between the windings or poles. As shown in FIG. 35E, the core 2140 of the stator assembly 2120 is made of a material with isotropic magnetic properties. FIGS. 35A, 35B, and 35C show cross-sectional views of a stator with winding coils 2150 superimposed on the stator core 2140. 40, the winding coils 2150 may be bonded to the core 2140 using potting material 2165. An outer surface 2166 of the potting material 2165 may provide for winding leads and thermocouple leads. Overall, the motor 2100 has a diameter defined by the stator diameter D1 (the diameter to the outer surface 2166 is D2) and a height H.

[0111] FIG. 35D shows the individual winding coils 2150. Three winding coils, one for each phase, may have thermocouples embedded therein. In one exemplary embodiment, the stator assembly 2120 is Wye wound with four flying leads (three line leads and one center tap). The stator assembly 2120 may be axially clamped so that the flying leads exit the stator ring at the outer diameter from the outer surface 2166. The stator core 2140 and winding coils 2150 may be potted with a potting material 2165 to provide a single, integrated "stator ring."

[0112] Individual winding coils 2150 are shown in Figures 35D and 38. Each winding coil 2150 has a different rectangular cross-section along the length of the coil. The width of the coil cross-section increases with radius, while its thickness decreases, so that the cross-sectional area of ​​the coil remains approximately constant along its length. Figure 38 illustrates this concept. The wire may be 25 AWG with insulation stable to 120°C or Class H. The coils are alpha-wound, starting and ending on the outside. To accommodate the change in coil cross-section and optimally utilize space, the wire grid varies from an 8x6 grid to a 10x5 grid along the length of the coil. The winding thickness decreases as the radius increases; therefore, the air gap spacing decreases accordingly. However, this is only one suggested grid pattern. Alternative, more efficient grid patterns may be employed that meet the space constraints of the windings.

[0113] 34 and 36, the rotor assembly of motor 2100 is generally designated 2115. For ease of assembly, rotor assembly 2115 is made up of two approximately equal halves, one of which is shown in FIG. 36C. Each half is magnetized in a different direction (or has a continuous change in magnetization direction at each pole).

[0114] The rotor assembly 2115 may also be made from a single ring, with magnetization varying continuously in two orthogonal directions (circumferential and pole length). The rotor halves may be made from low-carbon steel, such as 1018 steel. The rotor halves may be powder coated to prevent corrosion. The rotor assembly 2115 has multiple rotor poles, each containing two magnet pieces 2160. Figure 36E shows one rotor half and one of the magnets 2160 attached to it. Each rotor half may have approximately 30 magnets 2160, each radially magnetized. Adjacent magnets are magnetized in opposite directions. The rotor magnets 2160 may be made from neodymium with a residual magnetic flux density of approximately 1.3. Magnets with properties similar to N42UH, N42SH, or equivalent may be used. The magnet shapes may be cut from an already magnetized block and then ground to shape. Figures 36D and 39 show the two magnet pieces that comprise the poles of one rotor half. As shown, each piece may be magnetized so that the magnetization direction is parallel rather than radial. The magnets 2160 may be coated during grinding to prevent corrosion.

[0115] A radial flux motor may be employed instead of the hybrid motor 2100. Such a motor may utilize a three-phase brushless DC motor with slotless windings. In such a motor, the stator may be made of laminated silicon steel.

[0116] In one embodiment, the soft magnetic material includes a plurality of iron-containing particles and an insulating layer on the iron-containing particles. The insulating layer includes an oxide. The soft magnetic material is an agglomerate of magnetically permeable microdomains separated by insulating boundaries. The oxide of the insulating layer may include alumina. The iron-containing particles may have a body-centered cubic structure. The iron-containing particles may include silicon. The iron-containing particles may include at least one of aluminum, cobalt, nickel, and silicon.

[0117] In another embodiment, the soft magnetic material includes a plurality of iron-containing particles, each having an alumina layer disposed on the iron-containing particles. The alumina layer disposed on the iron-containing particles forms a body-centered cubic microstructure that defines agglomerates of microdomains with high magnetic permeability and low coercivity, separated by insulating boundaries. The iron-containing particles may include approximately 89 wt.% iron, approximately 10 wt.% aluminum, and approximately 0.25 wt.% carbon. The iron-containing particles may include silicon. The iron-containing particles may include at least one of aluminum, cobalt, nickel, and silicon. The iron-containing particles may be defined by an iron-containing core of uniform composition, and the alumina layer may include substantially pure aluminum oxide. The soft magnetic material may be defined by particles having an iron-aluminum alloy core of uniform composition, and the alumina layer may be defined by a concentration gradient from substantially zero aluminum oxide at the surface of the core to substantially pure aluminum oxide at the outer surface of the alumina layer. The body-centered cubic lattice microstructure may be substantially isotropic in the XZ, YZ, and XY planes.

[0118] In one embodiment of producing a soft magnetic material, a method includes providing iron-aluminum alloy particles, heating the iron-aluminum alloy particles to a temperature below the melting point of the iron-aluminum alloy particles but high enough to soften the iron-aluminum alloy particles, thermally spraying the iron-aluminum alloy particles, oxidizing the iron-aluminum alloy particles, depositing the iron-aluminum alloy particles on a substrate, and depositing a bulk of the iron-aluminum alloy particles on the substrate and further depositing a continuous layer of iron-aluminum alloy particles on the substrate, and heat-treating the bulk of the iron-aluminum alloy particles. The iron-aluminum alloy particles may comprise an alloy having a composition of about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. Heating the iron-aluminum alloy particles may include heating to less than about 1450°C. Thermal spraying the iron-aluminum alloy particles may include gas-atomizing the iron-aluminum alloy particles with a carrier gas. Thermal spraying of the iron-aluminum alloy particles may include using a high velocity air-fuel system in which a carrier gas operates at about 900°C to about 1200°C to atomize the iron-aluminum alloy particles. Thermal spraying of the iron-aluminum alloy particles may include using a high velocity oxygen-fuel system in which a carrier gas operates at about 1400°C to about 1600°C to deposit the iron-aluminum alloy particles as a thin coating. Thermal spraying of the iron-aluminum alloy particles may include using low energy plasma spraying. Oxidizing the iron-aluminum alloy particles may include forming alumina on the outer surface of the iron-aluminum alloy particles.

[0119] In one embodiment, the motor includes a stator including at least one core, a coil wound around the at least one core of the stator, a rotor having rotor poles rotatably mounted relative to the stator, and at least one magnet disposed between the rotor and the stator. The at least one core includes a composite defined by iron-containing particles having an alumina layer disposed thereon. The rotor poles and the stator, in combination with the at least one magnet, may direct magnetic flux between the rotor and the stator in a direction outward from a plane in three-dimensional space. The stator may be configured to approximate a cross-sectional shape defining a surface corresponding to the cross-sectional shape of the at least one magnet. A conical air gap may be disposed between the stator and the at least one magnet, allowing magnetic flux to flow along the radial, axial, and circumferential directions of the motor. The rotor poles may extend toward the stator, creating a conical air gap between the stator and the at least one magnet. The coil may have a radially tapered configuration. At least one core may be formed on a surface of the stator to form a slotless stator. The rotor may include a first rotor section and a second rotor section. The stator may include at least a first stator section and a second stator section.

[0120] In another embodiment, a motor includes a slotless stator including at least one core formed of a soft magnetic composite and a coil disposed on the at least one core; a rotor rotatably mounted relative to the slotless stator; and at least one magnet mounted on the rotor between the rotor and the slotless stator. The soft magnetic composite may include particles containing at least iron and having an insulating outer surface including alumina. The particles containing at least iron may include an iron-aluminum alloy. The motor may include an air gap having a conical cross section between the slotless stator and the at least one magnet. The slotless stator may include a wall forming a continuous surface, and at least one core may be formed in the wall. The soft magnetic material may include approximately 89 wt.% iron, approximately 10 wt.% aluminum, and approximately 0.25 wt.% carbon. The soft magnetic material may further include silicon.

[0121] In another embodiment, a slotless flux motor includes a stator defined by a continuous surface on which at least one core is disposed and a winding disposed on the at least one core; a rotor having rotor poles rotatably mounted within the stator; and at least one magnet mounted between the stator and the rotor poles. A conical air gap is defined between the stator and the at least one magnet, and the conical air gap allows magnetic flux to flow in the radial, axial, and circumferential directions of the motor. The at least one core includes a soft magnetic composite defined by iron-containing particles encapsulated in alumina. The iron-containing particles may include an iron-aluminum alloy that may include about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. The iron-containing particles may further include silicon. The iron-containing particles of the soft magnetic composite may include one or more of an iron-cobalt alloy, an iron-nickel alloy, and an iron-silicon alloy. At least one core may be self-supported on an inwardly facing surface of the stator and have a V-shaped cross section when viewed horizontally.

[0122] One embodiment of the composition includes a plurality of iron-containing particles and an insulating layer on the iron-containing particles. The iron-containing particles define agglomerates of magnetically permeable microdomains separated by insulating boundaries. The insulating layer may include an oxide. The oxide may be aluminum oxide. The iron-containing particles may have a body-centered cubic structure. The body-centered cubic structure may be substantially isotropic in three dimensions. The iron-containing particles may include at least one of aluminum, cobalt, nickel, and silicon. The agglomerates of magnetically permeable microdomains may have high magnetic permeability and low coercivity. The iron-containing particles may include about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. The insulating layer may be defined by an oxide layer having a concentration gradient. The iron-containing particles and the insulating layer may define a soft magnetic material.

[0123] One embodiment of the method includes heating iron-aluminum alloy particles, thermally spraying the iron-aluminum particles, oxidizing the iron-aluminum particles, and depositing the oxidized iron-aluminum particles on a substrate. The iron-aluminum alloy particles may include about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. Heating the iron-aluminum alloy particles may include heating to less than about 1450°C. Thermal spraying the iron-aluminum alloy particles may include spraying using a high-velocity air-fuel system, a high-velocity oxygen-fuel system, or low-energy plasma spraying. Oxidizing the iron-aluminum particles may include forming alumina on the outer surface of the iron-aluminum alloy particles. Depositing the oxidized iron-aluminum particles on a substrate may include forming a soft magnetic material.

[0124] One embodiment of the device includes a stator having at least one core, a coil on the at least one core, a rotor rotatably mounted within the stator, and at least one magnet mounted between the stator and the rotor. The at least one core may include a composition defined by iron-containing particles having an oxide layer disposed thereon. The stator may be slotless. Magnetic flux may be directed in three dimensions between the rotor and the stator. The device may further include rotor poles defined by an outward-facing surface of the rotor and stator poles defined by an inward-facing surface of the stator, with at least one magnet mounted on the outward-facing surface of the rotor. The cross-sectional shape of the at least one magnet may define a surface corresponding to the cross-sectional shape of the inward-facing surface of the stator. The at least one magnet and the inward-facing surface of the rotor may define a conical air gap between the rotor and the stator. The conical air gap may allow magnetic flux to flow radially, axially, and circumferentially around the device. The composition defined by the iron-containing particles may include an oxide layer comprising a soft magnetic material. The iron-containing particles may comprise an alloy having about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. The oxide layer may be aluminum oxide. The composition may further comprise silicon. The composition may comprise a concentration gradient in the oxide layer.

[0125] With reference to FIGS. 41-45, various exemplary embodiments for manufacturing the soft magnetic material 10 are described in the following examples. Example 1

[0126] For the deposition process 20 described herein, an HVAF system was selected due to its high deposition rate, producing material samples with dielectric boundary and electromagnetic properties. Two different HVAF settings were selected to evaluate the material properties. The first setting corresponded to a stoichiometric fuel-air mixture. The second setting corresponded to a leaner mixture with a lower carrier gas temperature. The second setting produced a microstructure with a lower percentage of fully fused particles. Additionally, a heat treatment process was performed on some of the samples produced using both settings. The samples were heated to a temperature of 1050°C (50°C above the eutectic temperature), held at that temperature in a reducing environment for 4 hours, and then slowly cooled to room temperature to produce Samples 1A and 2A, respectively, as shown in Table 1 (below). Samples were produced as thin rectangular samples and ring samples approximately 2 inches in diameter and 0.25 inches thick. The thin rectangles were used to examine the microstructure using an electron microscope and an X-ray diffraction system. The rings were used to characterize the magnetic properties according to ASTM A773 standard.

[0127] A cross-section of a thin rectangular sample was polished, etched, and observed using an electron microscope and an energy dispersive spectroscopy (EDS) system to generate an elemental map of the entire cross-section. Figure 41 shows the cross-section of sample 2A (electron image 1) and the elemental map corresponding to the elements iron, aluminum, and oxygen. Oxygen atoms are primarily concentrated at the grain boundaries, while iron atoms are absent from the grain boundaries. Aluminum atoms are more concentrated at the boundaries than in the grain interiors, indicating that the grain boundaries are composed of alumina, a good electrical insulator, while the grain interiors are composed of the desired soft magnetic material, the Fe-Al alloy. This observation is supported by the X-ray diffraction spectrum of the material, shown in Figure 42, which confirms the presence of alumina along with the Fe-Al alloy.

[0128] Thus, the insulating layer made of alumina can be stable even at high temperatures (unlike insulating layers made of iron oxide). From the electron microscope images, the thickness of the insulating boundary was predicted to be in the range of 100 nm to approximately 500 nm.

[0129] In accordance with the ASTM A773 standard, the magnetic properties of the ring-shaped samples shown in Figure 41 were also measured. The following properties were measured for Samples 1, 1A, 2, and 2A: magnetization curves (BH curves) up to a magnetizing magnetic field of 40 kA / m, flux density at 40 kA / m, B sat@40kA / m , coercive force, H c , the magnetizing magnetic field at a flux density of 1 T, H 1T , relative permeability at zero flux density, m r , DC energy loss (due to hysteresis), and AC power loss at magnetic flux density frequencies of 60 Hz and 400 Hz. The results for the samples are shown in Table 1. Table 1: Measured magnetic properties of ring samples 1, 2, 1A, and 2A compared to the Phase-1 sample (denoted P1). TIFF2025186457000002.tif70170

[0130] For soft magnetic materials such as those described here to be used in electric motors, it is necessary to maximize the saturation flux density and relative permeability and minimize the required magnetizing field, coercivity, DC energy loss, and AC power loss. The results in Table 1 show that Sample 1A has the highest saturation flux density, initial permeability, and lowest DC energy loss, while Sample 2A has the lowest AC power loss. The annealed samples have higher permeability, saturation flux density, and lower coercivity than their unannealed counterparts. Annealing reduces internal stresses and dislocation density, increasing grain size and reducing resistance to magnetic domain boundary movement. Samples 1 and 1A correspond to higher firing temperatures than Samples 2 and 2A, resulting in a higher proportion of fully fused grains associated with lower porosity. As a result, Sample 1A has higher permeability and lower coercivity than Sample 2A. In contrast, Sample 2A's lower proportion of fully fused grains results in lower eddy currents and correspondingly lower AC power loss.

[0131] Because the insulating layer is composed of alumina, which is stable at high temperatures, heat treatment is very effective in improving the saturation magnetic flux density and permeability, and reducing the coercive force without sacrificing the insulating layer and eddy current losses. Regarding samples 1A and 2A, these samples have more desirable magnetic properties than the sample represented by P1 in Table 1.

[0132] Further improvements in magnetic properties can be achieved by varying the particle chemistry and size as well as the process parameters. For example, there may be an optimal set of process parameters that results in a firing temperature between those of Samples 1 and 2, resulting in a low percentage of fully fused particles while simultaneously minimizing porosity. Using powders with larger particle sizes may also allow the boundaries of magnetic domains to move more freely, thereby reducing hysteresis loss. Lowering the carbon content of the alloy below 0.05% significantly reduces carbon impurities and reduces hysteresis loss. Furthermore, there may be an optimal level of aluminum in Fe-Al alloys, which may increase saturation flux density without compromising the integrity of the interparticle insulation. Example 2

[0133] The particle sizes and shapes examined above were in the 15–45 micron range and spherical in shape. Magnetic materials consist of aggregates of magnetic microdomains that grow in the direction of an applied magnetic field. When materials consist of aggregates of particles, the presence of an insulating layer can restrict domain boundary movement to the grain boundaries, thereby limiting the effective permeability and saturation magnetic flux density. Simulations of material properties may also indicate that the ideal "ratio" of particle size to boundary dimensions is 1000:1. Because the insulating layer thicknesses obtained above were 0.1–0.5 microns, a particle size in the 100–200 micron range is generally desirable.

[0134] Typical particle sizes in thermal spray processes using HVAF and HVOF are in the 15-45 micron range, as this range allows for sufficient velocity and temperature to form a dense solid deposit. To spray larger particle sizes, certain process modifications are required to increase the energy and enthalpy input to the particle.

[0135] To determine whether larger particle sizes could be sprayed, experiments were conducted using a thermal spray powder (Metco-450NS, available from Oerlikon Metco, Switzerland). This is a 95% nickel and 5% aluminum alloy with a larger particle size range of 45–90 microns. The thermal energy input to the particles was controlled by selecting the combustion chamber, and the mechanical energy input was controlled by selecting the appropriate injection diameter of the converging-diverging nozzle. After several experiments, a dense layer of deposited particles was obtained. Figure 43 shows the microstructure of the resulting material. The bottom material layer was sprayed using a smaller combustion chamber, and the top layer was sprayed using a larger combustion chamber. The velocity of the ejected particles was controlled by selecting the appropriate size of the converging-diverging nozzle.

[0136] Carbon is added to aid in the atomization process, but carbon does not form a solid solution with iron; instead, it forms precipitated carbides, which impede the movement of magnetic domain boundaries and ultimately reduce permeability and saturation magnetic flux density. Therefore, silicon (which improves permeability) was used instead of carbon to achieve atomization. At concentrations below 7.5%, silicon forms a solid solution with a BCC lattice structure and does not form precipitates. Furthermore, at low silicon concentrations, silicon does not prevent the formation of alumina at temperatures below 1500°C, as shown in the phase diagrams in Figures 44A and 44B. Figures 44A and 44B show the temperature contours up to 1400 °C for the Fe-9%Al-Si alloy, which exhibits a BCC structure (Figure 44A(a)), the Fe-9%Al-1%Si-O alloy, which is suitable for alumina formation (Figure 44A(b)), the Fe-10%Al-C alloy, which exhibits a BCC structure (Figure 44B(a)), and the Fe-10%Al-O alloy, which is suitable for alumina formation (Figure 44B(b)). After these considerations, the Fe-9%Al-1%Si alloy composition was selected for thermal spraying experiments. Powders with the above concentrations were successfully produced by gas atomization, and the carbon concentration was reduced to 0.04%. The addition of silicon slightly lowered the melting point of the alloy, which was expected to be advantageous for thermal spraying larger particles.

[0137] The presence of aluminum as an alloying element facilitates the formation of an insulating layer. However, it also reduces the saturation magnetic flux density of the material. At 10% by weight, the saturation magnetic flux density of the alloy is 20% lower than that of pure iron. Thus, it was determined that it would be desirable to have particles with a chemical composition that satisfies the following conditions:

[0138] (a) A sufficient concentration of aluminum at the surface to form a continuous layer of aluminum oxide at the surface, while at the same time having little or no aluminum below the surface to ensure a high saturation magnetic flux density.

[0139] (b) The aluminum on the surface must exist as a solid solution of iron and aluminum, rather than as elemental aluminum, because elemental aluminum has a melting point lower than the operating temperature of the thermal spray. Also, unoxidized elemental aluminum would form undesirable conductive boundaries around the grain regions. Example 3

[0140] To obtain approximate performance characteristics of the slotless motor 2000, an analytical model was developed and implemented using a computer modeling program. The model was used to obtain a desired set of motor parameters, including the number of stator and rotor poles, the number of winding turns, and approximate dimensions of the magnets and stator teeth. According to the model, a hybrid field motor with 20 rotor poles and matching the dimensions in Table 2 will achieve a 24% higher motor constant compared to a conventional motor designed with the same constraints. [Table 2: Motor Dimensions] TIFF2025186457000003.tif46170

[0141] However, analytical models have limitations in that they do not take into account the nonlinearity in the BH curve of soft magnetic materials and magnetic flux saturation. For the same reason, analytical models are not sufficient to estimate motor constant values ​​for other configurations. To obtain a more precise solution, motors with other configurations were analyzed using finite element analysis. First, an elaborate geometric model of the motor was developed, and then a finite element analysis of the motor was performed.

[0142] Optimization criteria for the motor design process included (a) maximizing motor efficiency under static, constant speed conditions, and (b) maximizing torque capacity under constant speed operating conditions.

[0143] Near-net-shape manufacturing was used to fabricate the Motor 2000 components. The ring-shaped components used to measure the magnetic properties were sprayed using a thermal process according to the ASTM A773 standard. The strategy used to obtain the ring samples was modified to obtain the stator geometry required to create the slotless, coreless motor shown in Figure 33. To obtain the stator geometries for other motors, a strategy was utilized that used masks and stencils and controlled the stencil movement according to the depth measurements of the material deposition (as shown in Figure 45). This required a measurement system to measure the thickness of the deposited material and a stencil actuation mechanism linked to a robot that controlled the spray system. A computer actuated the coordination between the measurement system, stencil actuation mechanism, and spray system.

[0144] Complex stencils and masks were employed to fabricate the resulting 3-D printed molds. The 3-D printed molds were then used to create stator prototypes. This prototyping capability facilitated further refinement of the stator design, especially for processes utilizing thermal spraying.

[0145] Referring now to FIGS. 46A-46C, an alternative embodiment of the motor shown in FIG. 32 is shown. In the illustrated embodiment, the motor is a slotted motor, as opposed to the slotless motor shown in FIG. 32. The stator 1906′ may have similar applicable features as the stator 1906, with poles and teeth provided, such that a cross-sectional view of the teeth 2202 and windings 2204 as viewed axially of the motor is shown in FIG. 46C. FIG. 46A is a cross-sectional view of the teeth 2202 and windings 2204 as viewed tangentially through the center of the teeth 2202. FIG. 46B is a cross-sectional view of the teeth 2202 and windings 2204 as viewed tangentially through the stator, away from the center of the teeth 2202. The tooth 2202 has a face 2206 and a ring portion 2208 connected via a core portion 2210. Here, the stator 1906' is constructed so that the cross-section of the windings 2204 does not substantially change and so that the cross-section of the teeth 2202 does not substantially change along the magnetic flux path. The face portion 2206 is shown having a conical surface that interfaces with the magnet portion of the rotor 1902 and an opposing surface that interfaces with the windings 2204. The core portion 2210 extends from the face portion 2206 to the ring portion 2208, forming a structure around which the wire of the windings 2204 is wound. Here, the core portion 2210 may have a non-uniform cross-section, such that the cross-section of the windings 2204 does not substantially change and so that the cross-section of the teeth 2202 does not substantially change along the magnetic flux path, as shown, for example, in FIGS. 46A and 46C. The ring portion 2208 may have a triangular cross-section as shown, providing abutment structure and magnetic flux paths for adjacent teeth. While the stator 1906' is described with the geometry shown, any suitable geometry may be provided. Stator 1906' or any other stator as described may have salient windings or distributed windings as shown. Similarly, any stator as described may have canted poles or any suitable pole geometry. Similarly, any stator as described may be made of any suitable soft magnetic material as described, or any suitable material, such as sintered, machined, laminated, etc.

[0146] It should be understood, however, that the above description is by way of example only. Those skilled in the art will be able to devise various alternatives and modifications. For example, features recited in the various dependent claims may be combined with each other in any suitable combination. Also, features extracted from the different embodiments may be selectively combined to form new embodiments. Accordingly, the above description is intended to cover all such alternatives, modifications, and variations that fall within the scope of the appended claims.

[0147] Finally, we present examples described in the claims of the first application of this patent family (Patent Application No. 2016-517291) as originally filed. [Example 1] A plurality of particles containing iron an insulating layer on the iron-containing particles; A composition wherein said iron-containing particles define agglomerates of magnetically permeable microdomains separated by insulating boundaries. [Example 2] The composition of example 1, wherein the insulating layer comprises an oxide. [Example 3] The composition of example 2, wherein the oxide is aluminum oxide. [Example 4] The composition of example 1, wherein the iron-containing particles have a body-centered cubic structure. [Example 5] The composition of example 4, wherein the body-centered cubic structure is substantially isotropic in three dimensions. [Example 6] The composition of example 1, wherein the iron-containing particles comprise at least one of aluminum, cobalt, nickel, and silicon. [Example 7] The composition of example 1, wherein the agglomerates of magnetically permeable micro-domains have high magnetic permeability and low coercivity. [Example 8] The composition of example 1, wherein the iron-containing particles comprise about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. [Example 9] The composition of example 1, wherein the insulating layer is defined by an oxide layer having a concentration gradient. [Example 10] The composition of example 1, wherein the iron-containing particles and the insulating layer define a soft magnetic material. [Example 11] Heating iron-aluminum alloy particles; thermally spraying the iron-aluminum particles; oxidizing the iron-aluminum particles; depositing the oxidized iron-aluminum particles on a substrate. [Example 12] The method of example 11, wherein the iron-aluminum alloy particles comprise about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. [Example 13] 12. The method of embodiment 11, wherein heating the iron-aluminum alloy particles comprises heating to below about 1450°C. [Example 14] 12. The method of claim 11, wherein thermally spraying the iron-aluminum alloy particles comprises spraying using a high velocity air-fuel system, a high velocity oxygen-fuel system, or a low energy plasma spray. [Example 15] 12. The method of claim 11, wherein oxidizing the iron-aluminum particles comprises forming alumina on the outer surface of the iron-aluminum alloy particles. [Example 16] 12. The method of example 11, wherein depositing the oxidized iron-aluminum particles on a substrate forms a soft magnetic material. [Example 17] a stator having at least one core; a coil on the at least one core; a rotor rotatably mounted within the stator; at least one magnet mounted between the stator and the rotor; wherein the at least one core comprises a composition defined by iron-containing particles having an oxide layer disposed thereon. [Example 18] 18. The apparatus of example 17, wherein the stator is slotless. [Example 19] 18. The apparatus of claim 17, wherein the magnetic flux is oriented in three dimensions between the rotor and the stator. [Example 20] The apparatus of Example 17, further comprising rotor poles defined by an outward facing surface of the rotor and stator poles defined by an inward facing surface of the stator, wherein the at least one magnet is mounted on the outward facing surface of the rotor. [Example 21] 21. The apparatus of claim 20, wherein the cross-sectional shape of the at least one magnet defines a surface that corresponds to the cross-sectional shape of the inwardly facing surface of the stator. [Example 22] 21. The apparatus of claim 20, wherein the at least one magnet and the inward-facing surface of the rotor define a cone-shaped air gap between the rotor and the stator. [Example 23] 23. The device of example embodiment 22, wherein the cone-shaped gap allows magnetic flux to flow radially, axially, and circumferentially around the device. [Example 24] 18. The device of example 17, wherein the composition defined by iron-containing particles having an oxide layer comprises a soft magnetic material. [Example 25] 18. The apparatus of example 17, wherein the iron-containing particles comprise an alloy having about 89 wt.% iron, about 10 wt.% aluminum, and about 0.25 wt.% carbon. [Example 26] Example 18. The device of Example 17, wherein the oxide layer is aluminum oxide. [Example 27] Example 18. The device of Example 17, wherein the composition further comprises silicon. [Example 28] Example 18. The device of Example 17, wherein the composition comprises a concentration gradient of the oxide layer.

Claims

1. a stator having at least one core, an outer wall extending in an axial direction, and a notch running continuously in a circumferential direction on an outer peripheral surface of the outer wall; a coil wound around the at least one core; a rotor having rotor poles and rotatably mounted relative to the stator; at least one magnet mounted between the stator and the rotor; a conical air gap between the stator and the at least one magnet; Equipped with the end of the outer wall is lower than, equal to, or exceeds the surface of the coil facing the axial direction, and the outer wall terminates at the outer edge of the coil; a dividing plane perpendicular to the axis of rotation extends through the stator and the rotor; the coil, the at least one magnet, and the conical air gap are configured together to allow magnetic flux flow between the stator and the rotor in a three-dimensional magnetic flux pattern that does not cross the dividing plane. Motor.

2. 2. The motor of claim 1, wherein the rotor poles and the stator cooperate with the at least one magnet to direct magnetic flux between the stator and the rotor outwardly of a plane in three-dimensional space.

3. The motor of claim 1 , wherein the stator is configured to approximate a cross-sectional shape defining a surface corresponding to a cross-sectional shape of the at least one magnet.

4. The motor of claim 1 , wherein the rotor poles extend toward the stator to define the conical air gap between the stator and the at least one magnet.

5. The motor of claim 1 , wherein the coil is radially tapered.

6. The motor of claim 1 , wherein the at least one core is formed on a surface of the stator to form a slotless stator.

7. The motor of claim 1 , wherein the rotor comprises a first rotor portion and a second rotor portion.

8. The motor of claim 1 , wherein the stator comprises a first stator section and a second stator section.

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