Discrete flux directing magnet assemblies and systems using same - Patents.com

Abstract

Magnetic arrays and related systems. An exemplary mechanical array includes a plurality of discrete magnetic segments. When the segments are arranged in an array, such as away from the influence of ferromagnetic materials, each segment includes magnetic poles with the same maximum magnetic field strength. When the segments are arranged in sequence along a circumferential array (i) with a rotating magnetic field along the array, and (ii) each segment is arranged in sequence close enough to its neighbors so that the magnetic fields interact with each other, magnetic flux channeling similar to that observed in a Halbach array is obtained. In another embodiment of the invention, the segments may be in physical contact with each other to cause magnetic flux channeling, or may be spaced close enough together so that the magnetic fields between adjacent segments in the array interact with each other to cause magnetic flux channeling.

Description

[Technical field]

[0001] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 165,107, filed March 23, 2021, entitled “Discrete Flux Directing Magnet Assembly.”

[0002] The present invention relates to synchronous electric machines, and more particularly, embodiments of the present invention include systems and methods for increasing the power and torque density of motors and generators. [Background technology]

[0003] Increasing the power and torque to mass ratios, or power and torque densities, of electric machines is key to introducing electric power into a wider range of new applications where machine mass and size are critical, such as aviation, turboshaft power generation, and wind power. With existing machine technology, it is possible to achieve power densities of the order of 5 kW / kg, but this is a limiting factor in many new applications. Further design improvements that achieve higher power and torque densities would also benefit existing applications such as electric vehicles. Potential benefits include higher efficiency in both energy conversion and transmission, as well as reduced carbon dioxide emissions, heat generation, and regulated emissions.

[0004] Theoretically, the highest power and torque densities would be achievable in fully superconducting synchronous machines, which would be capable of power densities of the order of 25 kW / kg or more. However, AC losses in the superconducting stator windings would only be tolerated at low speeds. Partially superconducting machines with DC rotors could in principle generate air-gap flux densities of several Tesla, and thus could achieve higher power and torque densities. However, magnetic saturation in the required back core limits the magnetic flux density in the air gap to less than 2 Tesla, and the heavy weight of the back core further limits the achievable power and torque densities. The need for cryogenic temperatures and the complexity of detecting and preventing quenches in rotating superconducting systems make the technology difficult to deploy unless much higher power levels and torque densities are reached.

[0005] In 1973, British-American physicist John C. Mallinson presented a magnetic theory for a new class of magnetization patterns in planar structures in which the magnetization direction is a spatially rotating magnetic flux with constant amplitude. In such an array of aligned permanent magnet segments, the magnetic field is increased on one side of the array while on the other side of the array the magnetic field is cancelled to near zero. See Mallinson, JC, IEEE Transactions on Magnetics, Vol. MAG-9, No. 4, pp678-682, December 1973. In a spatially rotating pattern, the magnetic flux flows from segment to segment in an array of magnet segments. An example of the application of such an assembly is the Halbach array, invented in 1980 by Klaus Halbach for charged particle beam optics in accelerators and the corresponding beamlines. Halbach, Klaus, Nuclear Instruments and Methods, 169(1):1-10 "Design of Permanent Multipole Magnets with Oriented Rare Earth Cobalt Material" (1980).

[0006] In particle accelerator applications, charged particle beams need to be bent, focused, and / or have chromatic corrections. This is done with electromagnetic coils that contain a certain number of precisely positioned pole pairs. A dipole arrangement for bending charged particle beams consists of one pole pair, i.e. n=1, with one north and one south pole. A coil configuration for focusing charged particle beams is a quadrupole arrangement, n=2, with two north and two south poles. For chromatic correction, to focus particles with different momentum to a precise focal point, higher pole pairs are required, n=3 or higher. In general, the desired magnetic field in the cross section of an infinitely long aperture can be described or synthesized as a superposition of so-called multipole components, i.e. a combination of selected multipoles, e.g. dipoles, quadrupoles, hexapoles, etc. The magnetic fields used in charged particle beam optics must be highly precise, similar to the stringent requirements placed on conventional optical lenses. Mathematically, this accuracy requirement is met if each magnet consists of a single multipole order, for example a pure quadrupole (n=2), with no contributions from lower or higher order terms.

[0007] Halbach arrays provide the high magnetic field homogeneity required for charged particle beam optics. In these magnet assemblies, the direction of the magnetic flux at any point is given in polar coordinates by the following equation: TIFF2024512061000001.tif13166TIFF2024512061000002.tif12166Here, B rem is the magnitude of the remanent magnetic flux density, and p is an integer indicating the number of pole pairs. The subscript "r" denotes the radial component of the magnetic field, and the subscript "q" denotes the tangential component of the magnetic field. Positive values ​​of p generate a magnetic field that points radially outward from the array, while negative values ​​of p generate a magnetic field that points radially inward from the array, i.e., toward the central axis of the cylinder.

[0008] Electrical machines require the same multipole configurations required by charged particle beam optics, but with less stringent magnetic field homogeneity requirements. In synchronous machine rotors, permanent magnet Halbach arrays provide a simple and energy-efficient implementation of the required multipole configurations, increasing the magnetic flux density on one side of the array and thus improving power and torque density. However, Halbach arrays, especially those with high pole counts, are expensive to manufacture and have therefore not become widespread.

[0009] To significantly improve the performance of synchronous machines in terms of power and torque density while remaining efficient, new design topologies are needed that integrate proven concepts with improved manufacturing techniques and optimization methods. Also needed are new topologies that implement the benefits of flux channeling demonstrated in Halbach arrays, extending them to the configuration of, for example, superconducting coils. The concept according to the present invention presents a solution that significantly improves the performance of synchronous machines with a new approach to flux channeling that avoids the manufacturing complexities of Halbach arrays. Summary of the Invention [Problem to be solved by the invention]

[0010] Several improved designs of electric machines are presented that allow unprecedented power and torque densities and improved efficiency. These concepts can be applied to permanent magnet based machines as well as superconducting coils. The use of permanent magnets as the magnetic field generating system avoids the complexities associated with cryogenic temperatures and the need to provide electrical energy to the rotating system. On the other hand, superconducting rotors have the potential to achieve much higher magnetic flux densities. The invention also allows the realization of magnetic gearboxes and their integration with electric machines. The embodiments presented below are merely illustrative and do not limit the scope of the invention.

[0011] It is well known that Halbach arrays offer significant advantages in the field generating rotor of synchronous machines over conventional magnet assemblies consisting of alternating north and south poles. Flux channeling in a circumferential array enhances the flux density on one side of the array where flux is needed, while reducing it to near zero on the other side where flux is not needed. A design concept is disclosed that produces flux channeling on demand, such as a Halbach array. Unlike the Halbach array, this design concept has the high mechanical stability required for machines operating at high RPMs, and offers scalability from very small to very large systems while significantly reducing manufacturing costs. The disclosed flux channeling system and method are directly applicable to superconducting rotors.

[0012] In one embodiment, the efficiency of the machine is improved by eliminating the magnetization losses of the back iron required for field shaping in the air gap and reducing the fringing fields, while in another embodiment, the elimination of the back iron achieves a significant increase in power density and torque density.

[0013] Magnetic gearing, which can be integrated with a motor or generator, can further increase the power and torque density of electric machines, where the disclosed magnetic flux channeling concept provides (i) high mechanical strength at significantly reduced cost compared to traditional Halbach arrays, (ii) significantly higher power transmission per unit mass than traditional mechanical or magnetic gears, (iii) gear efficiencies that can exceed 99%, and (iv) inherent overload protection with minimal or no maintenance.

[0014] Further optimization of power and torque density in electric machines requires increasing current loading in the stator windings and therefore also highly effective heat dissipation and cooling to ensure reliable operation. Maximum current loading in the stator windings can be achieved with Bitter Magnet technology (see Soobin An, A Feasibility Study to Apply the Bitter Magnet to Electric Power Devices, MT-26, Sept. 2019), in which the conductors are constructed of copper sheets containing hole patterns optimized for coolant flow that bring the coolant into direct contact with the heat generating conductors. Bitter Magnet technology offers excellent heat dissipation while using cost-effective manufacturing methods. [Means for solving the problem]

[0015] According to an exemplary embodiment of the present invention, a magnetic system suitable for use in a rotating machine or gearbox includes at least a first array structure extending along a central axis including at least a first plurality of similar discrete magnetic segments, each of the first plurality of magnetic segments (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a maximum magnetic field strength direction and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape with the maximum magnetic field strength direction facing outwardly of the surface, and an array of similar first magnetic segments (hereinafter referred to simply as the first array) arranged circumferentially around the central axis. (iv) each major side is fixedly positioned to extend in a direction parallel to the direction of extension of the major sides of the other segments of the first plurality of segments, and (v) is positioned to extend in a direction parallel to the central axis and to integrally form, in combination with the other segments of the first plurality of segments, a first array of similar magnetic segments, the first array being configured as the first ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position in the first ordered sequence, resulting in a shift in angular orientation of the magnetic poles between the magnetic segments in the first ordered sequence. The first plurality of segments in the magnetic system are positioned in contact with or sufficiently close to one or more other segments to additively combine or reduce the magnetic fields from the different segments, thereby providing a net magnetic field strength for the first array structure, with an increased magnetic field strength at one of the inner or outer periphery of the array and a decreased magnetic field strength at the other of the inner or outer periphery of the array. In one set of embodiments, the magnetic segments are in an ordered sequence where the magnetic segments are axially rotated relative to the other magnetic segments to sequentially shift the orientation of the characteristic maximum magnetic field strength direction between the segments, thereby resulting in increased magnetic field strength on one side of the array.The magnetic system may further include a support structure, whereby the first plurality of magnetic segments occupy fixed positions relative to the central axis and to each other, and the relative shift of the orientation of the characteristic maximum magnetic field strength direction between the magnetic field poles is fixed. The support structure may include a series of channels or grooves in which the magnetic segments are disposed. The magnetic segments and the channels or grooves may have complementary shapes or mating features that lock the rotational positions of the segments in place to fix the relative shift of the magnetic field direction in place. In another embodiment, the magnetic system includes a support structure formed along the central axis with a series of openings therein, and includes the first plurality of discrete magnetic segments axially rotated and disposed within the openings to provide the shift sequentially along the array. The support structure may include a series of pressed laminations bonded together, the laminations comprising non-magnetic material.

[0016] According to a further embodiment of the invention, the magnetic system further includes a second array structure extending along the central axis including at least a second plurality of similar discrete magnetic segments, each of the second plurality of segments (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a maximum magnetic field strength direction and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape with the maximum magnetic field strength direction facing outwardly from the surface, and fixedly arranging the segments in a second array of similar magnetic segments arranged circumferentially around the central axis (hereinafter simply referred to as the second array). a segment is axially rotatable about its surface prior to rotation of the first plurality of magnetic segments, (iv) fixedly positioned with its major sides extending in a direction parallel to the major sides of other segments of the first plurality of magnetic segments, and (v) positioned to extend in a direction parallel to the central axis, in combination with other segments of the second plurality of magnetic segments to integrally form the second array of similar magnetic segments, the second array being configured as the second ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position in the second ordered sequence, resulting in a shift in the angular orientation of the magnetic poles between the magnetic segments in the second ordered sequence. In an exemplary embodiment, the second array of magnetic segments is configured to provide a sequence of elements that rotationally shift the angular orientation of a magnetic field pattern, where the angular orientation of the magnetic field pattern rotates orthogonal to the central axis between different magnetic elements. In another embodiment of the system, the spatial rotation of the magnetic field pattern configures the magnetic flux in a manner that provides an increased magnetic field strength on one of the inner side or the outer side of the first array, while providing a decreased magnetic field strength on the other of the inner side or the outer side of the first array.In another embodiment, the first array includes n magnetic segments, and the magnetic field pattern between every one of the n segments is characterized by the angular rotational shift with respect to the angular orientation of the magnetic field pattern of an adjacent element in the sequence. In another embodiment, the second array includes m magnetic segments, and the magnetic field pattern between every one of the m segments is characterized by the angular rotational shift with respect to the angular orientation of the magnetic field pattern of an adjacent element in the sequence. The first array may include n magnetic field segments having a magnetic field pattern characterized by the angular rotational shift with respect to the angular orientation of the magnetic field pattern of an adjacent element in the sequence, less than one of the n segments.

[0017] The present invention also provides a synchronous electric machine having a first rotor and a stator winding arranged coaxially with respect to the other about a central axis extending in a direction along a frame, the stator winding being fixedly mounted to the frame and the first rotor being mounted to the frame for rotation relative to the frame and the stator winding, the first rotor and the stator winding each having a circumferential surface extending along the central axis. The first rotor includes a first plurality of discrete magnetic segments, each segment (i) having an elongated length along its major side in a direction parallel to the central axis relative to its width, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a direction of maximum magnetic field strength and the same maximum magnetic field strength, (iii) having a surface having a cross-sectional shape with the direction of maximum magnetic field strength facing outwardly from the surface, the segments being rotatable prior to being fixedly positioned in an array of first similar magnetic segments arranged circumferentially around the central axis, (iv) being fixedly positioned such that its major side extends in a direction parallel to the major side of other segments of the first plurality of segments, and (v) (vi) extending along the central axis, integrally forming a circumferential array of the first magnetic segments with other segments of the first plurality of segments having an inner circumferential side facing the central axis and an outer circumferential side facing away from the central axis, and (vi) being located in sufficient proximity to one or more other segments to additively combine or reduce magnetic fields from different segments, thereby providing a net magnetic field strength in the first circumferential array, increasing the magnetic field strength at one of the inner or outer circumferential sides of the array, while decreasing the magnetic field strength at the other of the inner or outer circumferential sides of the array. The major sides of the first plurality of segments may be, for example, cylindrical or elliptical cylindrical, such that the predetermined shape in cross section is circular or elliptical. The major sides of the first plurality of segments may be axially symmetric, but are not limited thereto. In one set of embodiments, all magnetic segments in the first array are composed of the first plurality of segments only.In another set of embodiments, all segments of the first array are dipole magnets. The first array of magnetic segments may be configured to provide a sequence of elements with rotationally shifted angular orientations of magnetic field patterns, along which the angular orientations of magnetic poles between different segments of the discrete magnetic segments are rotated orthogonally to the central axis as a function of position in the sequence, thereby providing a rotational sequence of the angular orientations of the magnetic poles including a rotation in the direction of maximum magnetic field strength. The magnitude of the increased magnetic field strength at one of the inner or outer periphery of the array relative to the reduced magnetic field strength at the other of the inner or outer periphery of the array may depend in part on the number of segments per magnetic pole and the specific sequence and angle of rotation of the magnetic poles. In another set of embodiments, the first array includes n magnetic segments, and the magnetic field pattern between each one of the n segments is characterized by a rotational shift of the angular orientation with respect to the angular orientation of the magnetic field pattern of the adjacent element in the sequence. If the first array includes n magnetic segments, the magnetic field pattern between less than n of the n segments may be characterized by a rotational shift in the angular orientation relative to the angular orientation of the magnetic field pattern of an adjacent element in the sequence. All of the magnetic segments of the first array may be spaced apart from one another or may be in contact with one another.

[0018] The foregoing embodiments of the synchronous electric machine may include a second rotor: the stator winding extends between an inner stator winding distance Wi and an outer stator winding distance Wo, and the inner stator winding distance Wi and the outer stator winding distance Wo are each measured from the central axis. The first rotor is an inner rotor IR that extends between an inner distance IRi and an outer distance IRo, and the distances IRi and IRo are each measured from the central axis, and IRo < Wi. The machine includes the second rotor mounted to the frame so as to rotate with respect to the frame and the stator winding, the second rotor being disposed as an outer rotor OR with respect to the inner rotor IR, and the second rotor OR extends between an outer rotor inner distance ORi and an outer rotor outer distance ORo, and the distances ORi and ORo are each measured from the central axis, and the outer rotor OR has a circumferential or cylindrical surface extending along the central axis. The outer rotor OR includes a second plurality of discrete magnetic segments, each segment in the second plurality of magnetic segments having a characteristic magnetic field pattern and being (i) fixedly arranged in a direction spatially parallel to each other, (ii) extending along the axis to integrally form a second circumferential array, (iii) capable of being disposed within a second stabilizing structure, and (iv) rotatable about the central axis so as to interact with the stator winding for torque generation.

[0019] In the above mentioned machine including a second rotor, the second array of magnetic segments may be configured to provide a sequence of elements with a rotational shift of the angular direction of the magnetic field pattern, where the angular direction of the magnetic field pattern rotates in a direction perpendicular to the central axis between different magnetic elements. The spatial rotation of the magnetic field pattern may configure the magnetic flux in such a way as to provide an increased magnetic field strength on one of the inner or outer periphery of the second array, whereas a decreased magnetic field strength on the other of the inner or outer periphery of the array. If the first array includes n magnetic segments, in one embodiment the magnetic field pattern between each one of the n segments is characterized by a rotational shift of the angular direction with respect to the angular direction of the magnetic field pattern of the adjacent element in the sequence. If the second array includes m magnetic segments, according to another embodiment the magnetic field pattern between each one of the m segments is characterized by a rotational shift of the angular direction with respect to the angular direction of the magnetic field pattern of the adjacent element in the sequence. For the different set of embodiments above, when the second array includes n magnetic segments, the magnetic field pattern between less than n of the n segments is characterized by a rotational shift in the angular direction relative to the angular direction of the magnetic field pattern of an adjacent element in the sequence.

[0020] According to another set of embodiments, there is provided a synchronous electric machine comprising a first rotor and a stator winding, each coaxial with respect to the other about a central axis extending in a direction along a frame, the stator winding being fixedly mounted to the frame and the first rotor being mounted to the frame for rotation relative to the frame and the stator winding, the first rotor and the stator winding each having a circumferential surface extending along the central axis, the first rotor including a first plurality of discrete magnetic segments, each segment (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a maximum magnetic field strength direction and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape with the maximum magnetic field strength direction facing outwardly of the surface, the segments being fixedly positioned in the first array of similar magnetic segments arranged circumferentially about the central axis, the first rotor including a first plurality of discrete magnetic segments, each segment (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a maximum magnetic field strength direction and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape with the maximum magnetic field strength direction facing outwardly of the surface, the first plurality of discrete magnetic segments being fixedly positioned in the first array of similar magnetic segments arranged circumferentially about the central axis ... a first plurality of segments that are rotatable about a central axis, (iv) fixedly positioned with their major sides extending in a direction parallel to the major sides of the other segments of the first plurality of segments, (v) including magnetic poles having a similar characteristic maximum magnetic field strength direction, and (vi) positioned to extend in a direction parallel to the central axis, and in combination with the other segments of the first plurality of segments, integrally forming a circumferential array of the first similar magnetic segments, the array being configured in the sequence with the magnetic poles of the magnetic segments rotating relative to one another as a function of position in the sequence, resulting in a shift in the angular orientation of the magnetic poles between the magnetic segments.

[0021] The major sides of the first plurality of segments may be cylindrical or elliptical such that the predetermined shape in cross section is circular or elliptical. Each major side of each of the first plurality of segments may be axisymmetric. The first array may consist of only the first plurality of discrete magnetic segments. All segments of the first array may be dipole magnets. In embodiments of the machine, the segments in the first plurality of segments may be required to not be pie-shaped elements and not be formed into asymmetric shaped elements in which the maximum magnetic field strength direction varies as a function of position with respect to the element shape. In other embodiments, the segments in the first plurality of segments are not formed into asymmetric shaped elements after magnetization so that the maximum magnetic field strength direction can vary as a function of position with respect to elements different from the shaped elements.

[0022] According to a disclosed embodiment of the present invention, none of the segments in the first plurality of segments are formed as identical magnetized elements, then molded or machined into different shapes from the same element, and then sequenced as a series of differently shaped elements whose maximum magnetic field strength direction varies as a function of position relative to the element shape. According to another embodiment, none of the segments in the first plurality of segments are molded and sequenced as a series of elements whose maximum magnetic field strength direction varies as a function of position relative to the element shape. For the machine described above, the first circumferential array of magnetic segments has an inner side facing the axis and an outer side facing away from the axis, so that the magnetic field strength increases at one of the inner side or the outer side of the array, while the magnetic field strength decreases at the other of the inner side or the outer side of the array. According to another embodiment, when the first circumferential array of magnetic segments rotates about the central axis, the magnetic field at the one side of the array exhibiting the increased magnetic field strength interacts primarily with the magnetic field of the stator winding for torque generation. The above-mentioned machine embodiment further includes a support structure formed along a cylindrical plane having a series of openings therein, each of the first plurality of discrete magnetic segments being rotatably disposed within one of the openings to provide the shift. Such a support structure may include a series of pressed laminations joined together, the laminations comprising a non-magnetic material. The aforementioned machine may include an inner rotor and an outer rotor. For example, if the stator windings extend radially between an inner stator winding distance Wi and an outer stator winding distance Wo, each of which is measured from the central axis, the first rotor may be arranged as an inner rotor IR extending between an inner distance IRi and an outer distance IRo, each of which is measured from the central axis, and the distances IRi and IRo are each measured from the central axis, and the first rotor may be arranged as an inner rotor IR extending between an inner distance IRi and an outer distance IRo. <Wiである。The machine further includes an outer rotor OR disposed as an outer rotor relative to the inner rotor IR and mounted to the frame for rotation relative to the frame and the stator windings, the second rotor OR extending between an outer rotor inner distance ORi and an outer rotor outer distance ORo, distances ORi and ORo each being measured from the central axis, the outer rotor OR having a circumferential or cylindrical surface extending along the central axis, the outer rotor OR including a second plurality of discrete magnetic segments, each segment in the second plurality of segments having a characteristic magnetic field pattern and (i) fixedly positioned in a spatially parallel direction relative to each other, (ii) extending along the axis and integrally forming a second circumferential array, (iii) positionable within a second stabilizing structure, and (iv) rotatable about the central axis to interact with the stator windings for torque generation. The second array of magnetic segments may be configured to provide a sequence of elements with a rotationally shifted angular orientation of a magnetic field pattern, the angular orientation of the magnetic field pattern rotating in a direction perpendicular to the central axis between different magnetic elements. The spatial rotation of the magnetic field pattern may configure the magnetic flux in such a way as to provide a reduced magnetic field strength on one of the inner or outer periphery of the array, while providing an increased magnetic field strength on the other of the inner or outer periphery of the array. The first array may include n magnetic segments, the magnetic field pattern between every one of the n segments may be characterized by a rotational shift of the angular orientation with respect to the angular orientation of the magnetic field pattern of a neighboring element in the sequence. According to another embodiment, in the second array including m magnetic segments, the magnetic field pattern between every one of the m segments is characterized by a rotational shift of the angular orientation with respect to the angular orientation of the magnetic field pattern of a neighboring element in the sequence.According to yet another embodiment, in the second array comprising n magnetic segments, the magnetic field pattern between less than n of the n segments is characterized by a rotational shift in the angular direction relative to the angular direction of the magnetic field pattern of an adjacent element in the sequence.

[0023] Also provided is a method of assembling a synchronous machine, wherein a first rotor and a stator winding are mounted to a frame, the first rotor and the stator winding are each coaxial with respect to the other about a central axis extending in a direction along the frame, the stator winding is fixedly mounted to the frame, and the first rotor is mounted to the frame for rotation relative to the frame and the stator winding. The first rotor and the stator winding are each formed to have a circumferential surface extending along the central axis, the first rotor being formed to have at least a first plurality of discrete magnetic segments arranged in a first array, each segment (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a direction of maximum magnetic field strength and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape such that the direction of maximum magnetic field strength faces outwardly of the surface, the first rotor being rotatable about an axis prior to fixed placement of the segment in the first array of similar magnetic segments arranged circumferentially about the central axis, the first array of magnetic segments being arranged in a direction parallel to the central axis, the first rotor being formed to have at least a first plurality of discrete magnetic segments arranged in a first array, each segment (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a direction of maximum magnetic field strength and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape such that the direction of maximum magnetic field strength faces outwardly of the surface, the first array of similar magnetic segments being arranged in a direction parallel to the central axis, the first array of ... a first plurality of segments having an inner circumferential side facing the central axis and an outer circumferential side facing away from the central axis, (iv) fixedly positioned such that its major side extends in a direction parallel to the major side of the other segments of the first plurality of segments, and (v) positioned such that it extends in a direction parallel to the central axis, integrally forming in combination with the other segments of the first plurality of segments the first array of similar magnetic segments, the first array being configured as the first ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position in the first ordered sequence, resulting in an angular shift of the magnetic poles between the magnetic segments of the first ordered sequence, the shift resulting in an increased magnetic field strength on one side of the first array versus a decreased magnetic field strength on the other side of the first array.

[0024] Also disclosed is a magnetic system suitable for use in a rotating machine or gearbox, comprising at least a first array structure extending along a central axis including at least a first plurality of similar discrete magnetic segments, each segment of the first plurality of segments (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to the central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a maximum magnetic field strength direction and a same maximum magnetic field strength, (iii) having a surface having a cross-sectional shape such that the maximum magnetic field strength direction faces outwardly of the surface, and each segment in the array of first similar magnetic segments arranged circumferentially about the central axis. prior to being fixedly positioned, the segment is rotatable about an axis about said surface, (iv) fixedly positioned such that its major sides extend in a direction parallel to the major sides of the other segments of the first plurality of segments, and (v) positioned such that it extends in a direction parallel to the central axis, and in combination with the other segments of the first plurality of segments integrally forms the first array of similar magnetic segments, the first array being configured as the first ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position in the first ordered sequence, resulting in a shift in angular orientation of the magnetic poles between the magnetic segments of the first ordered sequence.

[0025] In one set of embodiments of the magnetic system, the first plurality of segments are arranged in contact with or sufficiently close to one or more other segments to additively combine or reduce the magnetic fields from the different segments, thereby providing a net magnetic field strength for the first array structure, with an increased magnetic field strength at one of the inner or outer periphery of the array, while the magnetic field strength is decreased at the other of the inner or outer periphery of the array. The magnetic segments may be arranged in a sequence as a whole, and the magnetic segments are rotated about an axis relative to the other magnetic segments to sequentially shift the orientation of the maximum magnetic field strength direction characteristic between the segments, thereby resulting in the increased magnetic field strength at one side of the array. The magnetic system may further include a support structure in which the first plurality of magnetic segments occupy fixed positions relative to the central axis and relative to each other, and in which the relative shift of the orientation of the maximum magnetic field strength direction characteristic between the magnetic poles is fixed. The support structure may include a series of channels or grooves in which the magnetic segments are arranged. Thus, the magnetic segments and the channels or grooves may have complementary shapes or mating features that lock the rotational position of the segments and fix the relative shift in magnetic field direction in place. In disclosed embodiments, the support structure may include a series of openings formed therein and along the central axis, and the first plurality of discrete magnetic segments are rotated about the axis and positioned within the openings to sequentially provide the shift along the array. The support structure may include a series of pressed laminations bonded together, the laminations being made of a non-magnetic material.

[0026] The magnetic system may further include a second array structure extending along said central axis including at least a second plurality of similar discrete magnetic segments, each segment of said second plurality of segments (i) having an elongated length relative to its width and extending along its major sides in a direction parallel to said central axis, (ii) including magnetic poles having a similar characteristic magnetic field distribution including a maximum magnetic field strength direction and a same maximum magnetic field strength, and (iii) having a surface having a cross-sectional shape with said maximum magnetic field strength direction facing outwardly from said surface, and (iv) prior to fixedly arranging the segment in a second array of similar magnetic segments arranged circumferentially around said central axis, said surface being shaped to have a predetermined cross-sectional shape. a first plurality of segments arranged in a first direction, (iv) fixedly positioned with its major sides extending in a direction parallel to the major sides of other segments of the first plurality of segments, and (v) positioned to extend in a direction parallel to the central axis, integrally forming in combination with other segments of the second plurality of segments the second array of similar magnetic segments, the second array being configured as the second ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position in the second ordered sequence, resulting in a shift in the angular orientation of the magnetic poles between the magnetic segments in the second ordered sequence. The second array of magnetic segments may be configured to provide a sequence of elements including a rotationally shifted angular orientation of a magnetic field pattern, the angular orientation of the magnetic field pattern rotating perpendicular to the central axis between different magnetic elements. The spatial rotation of the magnetic field pattern may also be configured in such a way as to provide an increased magnetic field strength on one of the inner or outer periphery sides of the first array, while providing a decreased magnetic field strength on the other of the inner or outer periphery sides of the first array. In one embodiment, for the first array comprising n magnetic segments, the magnetic field pattern between each one of the n segments is characterized by a rotational shift in the angular direction relative to the angular direction of the magnetic field pattern of an adjacent element in the sequence.In another embodiment, for the second array including m magnetic segments, the magnetic field pattern between every one of the m segments is characterized by the angular rotational shift with respect to the angular orientation of the magnetic field pattern of an adjacent element in the sequence, and in another embodiment, when the first array includes n magnetic segments, the magnetic field pattern between less than n of the n segments is characterized by the angular rotational shift with respect to the angular orientation of the magnetic field pattern of an adjacent element in the sequence.

[0027] An embodiment of the electric machine according to the invention includes a back core disposed radially outward from the first plurality of magnetic segments in the first array of the first rotor and coaxially disposed with the first rotor, the stator windings extending along an air gap between the first rotor and the back core to generate an increased radial magnetic flux density in the air gap, the back core may be mechanically coupled to rotate synchronously with the rotor to avoid, reduce or eliminate the presence of a changing magnetic field that would cause magnetization in the back core.

[0028] If the machine includes a flux directing inner back iron, for example, positioned radially inward from the first plurality of magnetic segments in the first array of the first rotor and coaxially with the first rotor, the inner back iron may be mechanically coupled to rotate synchronously with the rotor, avoiding, reducing or eliminating the presence of changing magnetic fields that would cause magnetization of the inner back iron.

[0029] When the magnetic system includes the second array structure comprising magnetic elements, the system may further include a circumferential array between the first array and the second array, the circumferential array including ferromagnetic segments arranged in coaxial alignment with the respective arrays. [Brief description of the drawings]

[0030] The features and advantages of the present invention will be better understood from the following detailed description when read in conjunction with the accompanying drawings.

[0031] [Figure 1] FIG. 1 is a cross-sectional view of a conventional prior art synchronous machine.

[0032] [Figure 2a] FIG. 2a is a partial view of a cylindrical magnet assembly composed of pie-shaped elements with magnetization directions anti-parallel to adjacent segments.

[0033] [Figure 2b] FIG. 2b is a partial view of a cylindrical magnet assembly made up of pie-shaped segments with the magnetization direction sequentially rotated by 45° between adjacent segments.

[0034] [Diagram 3] FIG. 3 is a cross-sectional side view of a synchronous machine taken along a shaft with a segmented rotor magnet assembly.

[0035] [Figure 4] FIG. 4 is a cross-sectional side view of a synchronous machine with segmented rotor magnets and where the back core is not fixed to the machine housing but is mechanically coupled to rotate with the rotor.

[0036] [Diagram 5] FIG. 5 is a cross-sectional side view of a synchronous machine with a segmented rotor magnet assembly disposed about the periphery of the machine and a back-iron disposed adjacent the machine shaft and mounted to the machine housing.

[0037] [Figure 6] FIG. 6 is a cross-sectional side view of a synchronous machine having a segmented rotor magnet assembly in which the back-iron is mechanically coupled to the rotor for rotation instead of being fixed to the machine housing.

[0038] [Figure 7] FIG. 7 is a cross-sectional side view of a synchronous machine that does not include a back core and has a segmented dual rotor assembly.

[0039] [Figure 8] FIG. 8 is a cross-sectional view taken along the shaft of the machine showing two concentric separated flux directing arrays, each having five pole pairs of cylindrically shaped magnetic segments, with the inner flux directing array consisting of three segments per pole and the outer flux directing array consisting of five segments per pole.

[0040] [Figure 9] FIG. 9 is a cross-sectional view taken along the shaft of the machine showing a ring-shaped support structure for supporting bar-shaped magnetic segments with exemplary elliptical openings, with arrows indicating the direction of the respective long axes of the cylindrical array of elliptical openings and the potential magnetic field direction of the magnetic segments inserted therein.

[0041] [Figure 10] FIG. 10 is a cross-sectional view of the machine showing two concentric flux-directed magnet arrays, each having five pole pairs incorporating elliptical openings into which elliptical shaped magnetic segments are inserted.

[0042] [Figure 11] FIG. 11 is a perspective view of a machine having an exemplary magnetic segment made up of multiple permanent magnet subsegments inserted end-to-end into one exemplary opening in the support ring shown in FIG.

[0043] [Figure 12] FIG. 12 is a cross-sectional view of a magnetic gear system having an exemplary cylindrical array of magnetic poles each composed of an elliptical shaped magnetic segment and a rectangular shaped ferromagnetic segment in an air gap taken along a plane transverse to the cylindrical axis of symmetry.

[0044] The discrete magnetic segments, or the associated openings in which they are disposed, are shown in the figures as circular or elliptical shapes. Arrows drawn within those shapes correspond to the magnetization direction or rotational shift of the disposed segments, or the orientation of the elliptical opening in which they are disposed. In the figures, like reference numbers are used to indicate like components. While the features of the invention are illustrated diagrammatically, it is understood that in order to emphasize the features of the invention, various details, relationships, and components whose nature is self-evident may not be illustrated. The various illustrated features are not to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Before describing in more detail certain features related to the embodiments of the present invention, it should be noted that the present invention exists primarily in a combination of novel and non-obvious components and process steps. Certain conventional components and steps are omitted or not described in detail so as not to obscure the present disclosure with descriptions that would be obvious to those skilled in the art. However, other elements and steps that are appropriate for understanding the present invention are described in more detail in the drawings and specification. The disclosed embodiments are not intended to define limitations on the structures or methods according to the present invention, but are intended only to present examples that include more exemplary features that are essential, more permissive, and more exhaustive. In addition, in order to ensure clarity in the description of the present invention and the claims, a brief explanation of terms is provided below.

[0046] As used herein, "circumferential" refers to a configuration that extends partially or completely around an axis or body shape, such as a rotor, stator, or array of segments. For example, the exterior surface of a closed body shape, such as a stator winding that extends completely around a linear axis, has a circumferential shape because the exterior surface extends partially or completely around the axis. Such a closed body shape may be, for example, an electrical winding that has a cylindrical or cylindrical-like body shape that extends along an axis.

[0047] "Circumferential array" refers to an array of segments arranged circumferentially about an axis or about a body shape.

[0048] "Cylindrical array of segments" refers to an array of a series of constructed discrete segments, such as a series of bar magnets, extending partially or wholly circumferentially around an axis or body shape, where the segments may be arranged as a sequence of parallel segments to provide spatial attributes along a real or imaginary cylindrical surface. The spatial attributes may relate to geometric features in space, or to magnetic field distribution and magnetic flux density as a function of position on a real or imaginary cylindrical surface.

[0049] "Cylindrical-like" refers to a shape that resembles or sufficiently approximates the shape and symmetry of a cylinder, even if it has multiple distinct walls or variations in diameter.

[0050] A "discrete magnetic segment" (also simply referred to as a "segment") is a permanent magnet or an electromagnet (e.g., an electromagnetic coil). In the case of a permanent magnet, the segment may be in the form of a rod-like, i.e., elongated structure. This structure may be monolithic or may be composed of multiple sub-segments, i.e., multiple magnets, that are smaller in size and arranged end-to-end, i.e., pole-to-pole, to achieve the desired length of the segment. Permanent magnet segments are not limited to any particular shape in cross section, and such segments disclosed for use in embodiments of the present invention have an elongated shape extending along a linear axis, and are not limited to any particular shape in cross section, i.e., a surface cut along a plane perpendicular to the axis. The cross-sectional shape of such segments may be, for example, circular, cylindrical, elliptical, symmetrical, or asymmetrical.

[0051] "Flux channeling," in the context of magnetic fields, refers to the net magnetic field pattern resulting from the interaction of magnetic flux emanating from multiple magnetic sources. As an example, in the case of an array of circumferentially arranged magnets, flux channeling can result in asymmetric magnetic field distributions for the individual magnets of the array. In a conventional Halbach array, magnetic field interactions can result in increased magnetic field strength on one side of the magnet array and decreased magnetic field strength on the other side of the array.

[0052] By "rod shaped structure" is meant an elongated member extending along a linear axis, without any limitation on the shape of the structure along a plane perpendicular to the long axis. The discrete magnetic segments used to form the arrays according to the present invention are generally elongated about a long axis and may have a variety of shapes in cross section, i.e., along a plane perpendicular to the long axis.

[0053] "Shape in cross section" means, with respect to a discrete magnetic segment or coil, the shape along a plane perpendicular to the major axis of the segment, e.g., the linear axis along which the elongated shape of the segment extends.

[0054] A prior art embodiment of a conventional synchronous machine is shown in Figure 1. The concept is the same for generators and motors. In the case of a generator, mechanical energy is fed to the rotating shaft 104 of the machine. This mechanical energy is converted to electrical energy available as output from the stator windings 102. In the case of a motor, electrical energy is fed to the stator windings 102 and converted to mechanical energy available at the rotating shaft 104 for any kind of propulsion.

[0055] The schematic diagram shown in Figure 1 illustrates the basic functioning of a synchronous electric machine. The stator 102 and rotor 100 are arranged concentrically along a common axis, and the stator windings 102W are arranged so that the current flowing in each winding is primarily axial, i.e. along the direction of the shaft 104. The stator of a synchronous machine may be configured with multiple windings 102W (not shown) of appropriate phase to generate a rotating magnetic field. Ideally and optimally, the magnetic field lines of the rotor of a conventional machine should extend radially from the common axis, i.e. perpendicular to the primary direction of current flow in the stator windings.

[0056] The rotor 100, which transfers mechanical energy to and from the system, is coupled to the machine shaft 104. The rotor is surrounded by a concentric back core 103 along which a so-called air gap 102 exists between the rotor and the back core. The stator windings 102W are arranged in the air gap G. The rotor 100, consisting of permanent magnets or electromagnets 101, provides a magnetic field in the air gap to interact with the magnetic field generated by the stator windings 102W. To convert the mechanical energy to electrical energy, a torque is applied to the shaft 104 to rotate the rotor 100, and an electromotive force (emf) is induced at the terminals of the stator windings due to the interaction of the changing rotor magnetic flux with the current flow in the stator windings, and the system operates as a generator. When operating as a motor, a rotating magnetic field is generated around the axis of the machine when an alternating voltage with an appropriate phase shift is applied to excite the stator windings 102W. The interaction between the rotating magnetic field generated by the stator windings and the magnetic field of rotor magnet 101 causes the rotor to rotate in synchronization with the frequency of an AC voltage applied to excite the stator windings.

[0057] To achieve maximum energy transfer between the rotor magnets 101 and the stator windings 102, the magnetic field in the stator winding air gap G should be oriented radially. As mentioned for the conventional motor, the Lorentz force F acting on the conductors of the stator winding is given by F=I×B, where all quantities are vector quantities. I represents the current in the stator winding 102, and B is the magnetic flux density caused by the rotor magnets in the air gap interacting with the current flowing through the stator winding. The force given by the vector cross product has a maximum value when the direction of the current I and the direction of the magnetic flux density B are perpendicular to each other. The Lorentz force is zero when the angle between the two quantities is 0°. As can be seen from this relationship, since the conductors of the stator winding are oriented axially, the mechanical output is optimized when the magnetic field direction of the rotor is oriented radially with respect to the common axis. The back iron 103 surrounds the field generating rotor, which allows the rotor magnetic field lines to be more radially aligned.

[0058] The power of the above synchronous machine is given by the following relationship: TIFF2024512061000003.tif12166Where, ω is the rotational speed, L is the axial length of the machine, D is the average diameter of the stator winding in the air gap, B R is the magnetic flux density in the air gap and As is the current load of the stator winding. This equation shows that the power of the machine is proportional to the magnetic flux density in the air gap of the stator winding. The magnetic flux density of the cylindrical system required for the rotor can be increased if the system is equipped with a flux channeling array of magnetic elements such as in a cylindrical Halbach array. In such a magnet configuration, each magnetic pole is divided into elements and the magnetization direction of the individual elements changes from element to element. Conventional permanent magnets have north and south poles on opposite faces of the array, but by appropriately rotating the magnetization direction from element to element in the array, the magnetic flux of the magnet can bend or channel and generate magnetic flux mostly on only one side of the array. In this case, a ring magnet assembly consisting of permanent magnets or electromagnets can be manufactured to have substantially only inward or outward magnetic flux. This field bending (called flux channeling) not only confines most of the emerging magnetic flux to one side of the system, but also results in a significant increase in the emerging magnetic flux density compared to conventional magnets with opposing north and south poles. The field bending achievable with flux channeling arrays according to the present invention can be improved by as much as a factor of two in some cases.

[0059] In principle, the power output of a synchronous machine can be significantly improved if the field generating rotor system is implemented as a flux channeling array, e.g., with a conventional Halbach array of pie-shaped magnetic segments, instead of a conventional magnet assembly with opposing north and south poles. A comparison of the performance of a conventional magnet assembly, such as that shown in Figure 2a, with that of a system incorporating a flux channeling array, such as that shown in Figure 2b, reveals the advantages of the system incorporating the flux channeling array over the conventional system.

[0060] FIG. 2b shows two poles of a complete Halbach array, each pole consisting of four elements 121. Each pi-shaped element 121 of this array has a different magnetization direction. The magnetic field strength of a permanent magnet depends on the shape of the magnet, and the magnetic field is strongly dependent on the presence of nearby ferromagnetic material, not air. In assembled pi-shaped segments, the magnetic field lines are channeled from segment to segment based on the low reluctance of ferromagnetic material compared to air. On the other hand, if the same pi-shaped element is in air, some of its magnetic field lines will return through the element itself, reducing the magnetic field that can be measured on the outside. All pi-shaped elements of a Halbach array have the same residual magnetic field B rem When the magnetic fields are magnetized at θ = 0.05, the assembled system can be made to very closely approximate the ideal magnetic field configuration given by Equations 1 and 2.

[0061] Based on the flux channeling of the complete Halbach array, the flux density can be increased on the inside 122 of the ring and eliminated on the outside 123, or conversely, the flux density can be increased only on the outside of the ring. However, in practice, the manufacture of pie-shaped permanent magnets with magnetization direction 121 varying around the longitudinal axis of each segment is rather complicated, time-consuming, and expensive. This is because the permanent magnets are manufactured as rectangular parallelepipeds with the same magnetization direction 121. The magnetized parallelepipeds are then individually machined to obtain the required magnetization direction. Based on the brittleness and hardness characteristics of the permanent magnet material and the strong forces acting in the vicinity of other ferromagnetic materials, the manufacturing and assembly process is complicated, difficult, and not as practical as desired for many applications.

[0062] Furthermore, assembling the pieces into a doughnut-like shape and joining them together in the presence of strong opposing magnetic forces is a complex process. The resulting assembly is usually then overlapped to gain mechanical robustness. In many applications, the ultimate cost of such an assembly outweighs the resulting benefits, and it seems more economical to simply increase the size of the conventional machine to increase power and torque.

[0063] However, with a flux channeling array in accordance with the present invention, including discrete magnetic segments, all of which have the same magnetization direction in an exemplary embodiment (see FIG. 10), it becomes more practical and economical to realize a synchronous electric machine that provides similar benefits as expected from a conventional Halbach array.

[0064] One embodiment of an exemplary system 130 according to the invention is shown in FIG. 3 with a flux channel permanent magnet array 107 mounted on the shaft 104 of the machine to form a magnetic field generating rotor. The representation of the magnet array 107 is schematic. Four sub-segments of the array 107 are shown only to show that the segment is a collection of individual magnetic sub-segments. It does not show how the magnetic segments are oriented in the assembly. With the help of a concentric back-iron 103 arranged radially outside and coaxially with the rotor, a radially increased magnetic flux density is generated in the air gap G between the magnetic field of the rotor 100 and the back-iron 103, where the stator windings 102W are arranged.

[0065] The efficiency of an electric machine is strongly affected by magnetization losses in the back core, which is exposed to magnetic field changes associated with the rotating field of the rotor. These magnetization losses can be significantly reduced by mechanically coupling the back core to the rotor, as in system 135 shown in Figure 4. In this case, the back core 111 is mechanically coupled to rotate synchronously with the rotor 108, so that no magnetic field changes occur that would cause the back core 111 to become magnetized.

[0066] According to another embodiment of the invention shown in Figure 5, the flux channel array 113 is positioned on the outside of the stator 102 facing away from the central axis, and the flux directing core 112 is positioned on the inside of the stator 102 facing the central axis. This configuration allows a higher flux density to be generated in the air gap G between the stator 102 and the rotor magnet array 113 for the same machine dimensions, thereby resulting in higher power and torque densities. Also, referring to system 45 of Figure 6, the core 112 is again mechanically coupled to the flux channel array 113, thereby reducing magnetization losses in the core.

[0067] In accordance with yet another embodiment of the present invention, system 150 shown in FIG. 7 illustrates a further improvement in the magnetic flux density of an electric machine in the air gap 102, achieved by replacing the outer back core (e.g., as shown in FIGS. 3-6) with another flux channeling array of discrete magnetic segments 110. In this case, as described above, the inner flux channeling array 109 generates outward magnetic flux, and the outer flux channeling array 110 replaces the back core and generates inward magnetic flux. The opposing flux channeling arrays (109 and 110) provide (i) the desired radial flux direction, (ii) a further improvement in the magnetic flux density in the air gap achieved by the overlapping of the inner and outer flux channeling arrays, and (iii) a fringe field without the need for additional shielding. The two opposing flux channeling arrays (109 and 110) are mechanically coupled to the rotor 108, which is mechanically coupled to the shaft 104.

[0068] In contrast to machine configurations that require a back core, opposing flux channeling arrays allow for higher flux densities in the air gap. Iron exhibits magnetic saturation around 2 Tesla, so if the flux density in the air gap is not limited to this value, the iron will act like air and will lose its function. Even below 2 Tesla, the back core thickness must be increased according to the flux density in the air gap to radially direct the magnetic field in the air gap and suppress the fringing fields. However, the increased iron thickness increases the machine weight, counteracting the increase in power density and torque density that comes from the increased flux density. The opposing flux channeling array concept removes this limitation, allowing the use of superconducting dipole coils instead of permanent magnets with a flux density in the air gap of several Tesla.

[0069] US Patent Application US2018 / 0226190 discloses a manufacturing process for Halbach arrays where the entire array is magnetized in a single step. This is achieved with the aid of magnetizing coils that generate a flux direction that changes continuously as a function of azimuthal position around the Halbach ring (see Equations 1 and 2). This technique is best applied to arrays limited in diameter to 50 mm to 200 mm with a maximum pole count of less than 12. Magnetizing permanent magnet materials such as NdFeB requires a flux density of several Tesla. This makes it impractical to manufacture large continuous Halbach arrays such as those required for wind turbine generators. The magnetizing coils required are very large and have correspondingly large inductances. Very high voltages and powers are required to generate the pulsed magnetic field required at a flux density of several Tesla. Magnetizing rings for electric machines requiring pole counts of 20 or more with sufficient radial thickness presents additional challenges. The internal magnetic field of the multipole coils required for the magnetizing process decreases as the exponent increases towards the center of the system. For a tetrapole, i.e. a system with four poles, the magnetic flux density decreases linearly as a function of radius. For a general n-pole, the magnetic flux density is 1 / r n-1As the magnetic flux density decreases rapidly towards the center, it becomes increasingly difficult to obtain sufficient magnetic flux density for magnetization inside a ring magnet of a given radial thickness. To overcome this phenomenon, a very large magnetizing field is required to penetrate the ring with the necessary magnetic flux density for radially uniform magnetization.

[0070] As previously mentioned, the manufacturing complexity of conventional Halbach arrays, which consist of appropriately magnetized pie-shaped segments, has hindered their widespread adoption. In many applications, the ultimate cost of such assemblies outweighs the resulting benefits, making it more economical to increase power and torque by increasing the size of conventional machines.

[0071] In accordance with the present invention, the manufacturing difficulties of incorporating conventional Halbach arrays into rotating machinery can be avoided by relying on alternative designs other than those requiring a continuous ring-like array or a cylindrical assembly formed of discrete pie-shaped pieces. An embodiment of the present invention provides a flux directing magnet assembly consisting of discrete permanent magnets or discrete normally conducting or superconducting coils arranged in an array that extends along the contour of a cylindrical surface, i.e., the cylindrical plane. The individual magnets in the array extend in a direction parallel to the central axis of the cylindrical surface.

[0072] Referring to FIG. 8, there is shown a cross-sectional view of two concentrically arranged flux directing magnet assemblies suitable for operation as a rotating electrical machine or magnetic gear. The circles 303 are each a bar shaped permanent magnet or dipole coil, referred to herein as a magnetic segment. In a preferred embodiment, all the magnetic segments 303 in one of the rings are identical and similarly magnetized. However, to generate the magnetization direction required for magnetic flux channeling, each element is rotated relative to the other. The desired magnetization direction for each magnetic segment is indicated by the arrows. The magnetic segments of the inner ring (302) can also be equivalent to the elements of the outer ring 300.

[0073] The illustrated embodiment is suitable for operation as a dual rotor motor or generator. Other embodiments may consist of a single flux directing magnet assembly applicable to machines with a single rotor, as conceptually shown in Figures 4, 5 and 6. Referring to Figure 8, each flux directing magnet assembly 300 and 302 may include a series of permanent magnets in the form of coils or rod elements called pole segments. In embodiments where the segments are permanent magnets, the segments may be spaced apart from one another, but the surfaces of adjacent pole segments, called major sides, may be in close proximity or in contact with one another. The cross section shown in Figure 8 is taken along a plane transverse to the cylindrical axisymmetric common to each array of rod segments. The inner array 302 of rod segments of a concentric pair projects a radially outward magnetic flux determined by the magnetization directions shown, and the outer array 300 of the concentric pair projects a radially inward magnetic flux determined by the magnetization directions shown. The arrays of exemplary bar-shaped magnetic elements (300 and 302) are each configured as a flux-directing magnetic assembly with each individual bar-shaped magnetic segment having an appropriate magnetization direction. The embodiment shown in FIG. 8 produces a magnetic field with five pole pairs. Each such assembly of discrete magnets extends in a cylindrical plane along an axis of symmetry. For the inner magnetic array 302 with outwardly projected flux, each pole is composed of three segments. For the outer magnetic array 300, each pole is composed of five segments. The illustrated magnetization directions can be determined by Equations 1 and 2, which are repeated here for convenience. TIFF2024512061000004.tif12166TIFF2024512061000005.tif12166This ideal configuration given by Equations 1 and 2 is best approximated by a large number of segments per pole, however, we show that even five segments per pole provides a good approximation to the ideal configuration suitable for practicing the present invention.

[0074] The concentric arrangement of two arrays 300 and 302 of bar-shaped segments shown in Fig. 8 can be used as a rotor for a synchronous electric machine, the underlying concept being applicable to magnetic gear operation as well. In a motor application, a stator winding is placed in the air gap between the inner array 302 and the outer array 300 of bar-shaped magnetic segments. Since the current in the stator winding flows in a direction perpendicular to the plane of the cross section of Fig. 8, and the Lorentz force on the conductor of this stator winding is given by the cross product F = I x B of the current in the conductor and the surrounding magnetic flux, each concentric opposing array generates the radially oriented magnetic flux density required to achieve an optimized torque.

[0075] In practical applications of electric machines and magnetic gears incorporating the above-mentioned concentric arrays of rod elements, the number of pole pairs, the number of segments per pole, the cross-sectional shape of the individual magnets, the air gap between the two magnet arrays, and the radial thickness of the arrays may each be optimized to achieve the best possible magnetic flux channeling.

[0076] The shape of each bar magnet, ie, permanent magnet or dipole coil, of the flux directing magnet array may be of various shapes, either symmetrical or asymmetrical, when viewed in cross section.

[0077] In one embodiment, the bar magnetic segments are a series of similar uniformly spaced cylindrical segments that collectively form a cylindrical array pattern for each flux directing magnet assembly. In this example, each permanent magnet has a magnetization direction oriented along the axis of its cylindrical shape, and the magnets may be individually rotated as a function of position relative to the assembly to provide a pattern of magnetization directions that shift periodically along the magnetic poles, similar to the pattern in a conventional Halbach array, and the magnetization directions required for any specified multi-pole configuration n.

[0078] Exemplary bar-shaped permanent magnets (schematically shown as cylindrical in FIG. 8) are each inserted into a series of openings or perforations 601. The openings can be formed in a cylindrical support structure 600 as shown in FIG. 9. The support structure can be manufactured from pressed laminates having precision openings 601 for inserting the permanent magnet segments. Such laminates can be manufactured at relatively low cost with an accuracy of 0.01 mm or less. The laminate material can be non-magnetic, e.g., titanium-based, to provide a relatively high strength, low density support structure.

[0079] During motor excitation, each magnet in the illustrated concentric array of flux-directing magnetic segments experiences a torque that may cause the magnet to rotate in position within the cylindrical support structure in response to the applied Lorentz force. Such rotation can be prevented, for example, by using magnets with an elliptical cross section as shown in FIG. 10, with openings in the support structure having a complementary shape that locks the bar-shaped magnetic segments in place under the applied Lorentz force. Alternatively, the bar-shaped magnets may be chemically bonded to the support structure, such as with a suitable epoxy, to prevent rotation or axial movement, or the major side surfaces, such as those having a circular cross section, may include keys that interlock with mating keyways in the support structure.

[0080] A feature of the disclosed embodiments is that the arrays can include discrete magnets of any type that can be manufactured from any available permanent magnet material, such as the highest grade NdFeB available (e.g., N52), without requiring further development of the permanent magnet manufacturing and magnetization process. Extremely large magnetic flux density B in the air gap R For applications with the highest power and torque densities, requiring (see Equation 3), superconducting dipole coils can be used as the magnetic elements, in which case all the coils in the two rings can be in series, or the current in the outer ring can be different from the current in the inner ring, as appropriate.

[0081] For designs calling for arrays with long axial segment lengths, as shown in the partial view of Figure 11 for one of the perforations, multiple discrete sub-segments 400 of permanent magnets can be inserted end-to-end into each perforation of the laminated support structure 401. Multiple magnets can be placed in the same opening without having to overcome repulsive forces, and magnets inserted end-to-end into the same opening do not need to be glued together.

[0082] The discrete array of spaced apart magnetic elements of the present disclosure is expected to be significantly more mechanically robust than conventional Halbach arrays formed of discrete pie-shaped pieces, and therefore well suited for electric machines operating at high RPMs. Conventional Halbach arrays are made of segments of brittle material bonded together and typically overlapped with a glass epoxy.

[0083] Compared to conventional Halbach arrays, the manufacturing of the flux-directed discrete magnet assemblies in this disclosure is a more economical manufacturing process to redirect the magnetic flux across a small air gap. Notably, all the bar magnet segments in the assembly can be identical. When assembling magnet segments with long axial length with individual short magnets, a sorting process can be applied to ensure that all the bar segments in the ring have equal residual field. In the manufacturing of permanent magnets, it is common for there to be a few percent variation in the residual field from magnet to magnet. By measuring all magnets and sorting them accordingly, the variation in field strength between the bar segments can be minimized and the torque ripple of the machine can be avoided.

[0084] This technology is well suited for magnetic gearboxes such as those disclosed in U.S. Pat. No. 3,378,710, since it is possible to manufacture cost-effective flux-directing discrete magnetic assemblies with the highest magnetic flux density in the air gap in almost any size.

[0085] 12 shows a schematic of another embodiment of spaced apart discrete magnetic rod segments 505 in a pair of concentric cylindrical arrays (500 and 502) that comprise a flux channeling magnet assembly. A third ring 503 containing multiple ferromagnetic segments 504 is placed in the gap between the two flux channeling magnet array rings. The illustrated embodiment includes two rings (500 and 502) containing permanent magnets and an insert ring with ferromagnetic segments 503. The two rings are a flux channeling assembly.

[0086] FIG. 12 is a cross-sectional view along a plane intersecting the common axis of symmetry of the two arrays. The elements (505) of each cylindrical array extend along one of two imaginary concentric cylindrical surfaces, as in the previous figures (FIGS. 8 and 10). When the magnets (505) and ferromagnetic segments (504) of the different rings approach each other while one of the arrays rotates about its common axis, these different elements attract or repel each other, behaving in a functionally similar manner to the meshing teeth of mechanical gears in two rotatable rings. The array of magnetic elements provides a motion ratio comparable to that of conventional mechanical gears, but the magnetic gears function without contacting each other. Therefore, there is no mechanical wear of the interacting / mating surfaces and no noise is generated. The gears are allowed to slip without damage. Since the inner and outer arrays of magnetic elements have the same number of pole pairs, the system functions like a conventional clutch with maximum allowable torque transmission. Flux directing discrete magnet assemblies provide a gear system that is more advantageous than conventional SN magnet assemblies, in part because the conventional assemblies require a back iron and do not provide the same high flux density in the air gap. The present invention provides a cost-effective magnetic gear system with high torque transmission density.

[0087] This magnetic gear arrangement can be combined with the synchronous electric machine embodiment of the present disclosure. For wind turbine generators with very low rotational speeds, i.e., less than 20 RPM, a magnetic gear can be connected to the wind-driven propeller, but this magnetic gear implementation allows the generator to be driven at significantly higher rotational speeds. Since the power of the electric machine is proportional to the rotational speed, the generator can be correspondingly smaller in size, and the generator output frequency increases, facilitating the necessary commutation. Since the mechanical gearbox in a wind turbine generator has been found to be the element with the lowest mean time between failures in the entire system, the magnetic gearbox with inherent slip capability significantly improves reliability. [Features and characteristics of the present invention]

[0088] The present invention allows magnetic flux channeling technology to be used without the constraints that have limited it to limited applications.

[0089] FIG. 2b shows two poles of a complete Halbach array, each pole consisting of four elements 121. Each pie-shaped element 121 of the array has a different magnetization direction. The magnetic field strength of a permanent magnet depends on the shape of the magnet, and the magnetic field strongly depends on the presence of nearby ferromagnetic material instead of air. In assembled pie-shaped segments, the magnetic field lines are channeled from segment to segment based on the low reluctance of ferromagnetic material compared to air. On the other hand, if the same pie-shaped element is in air, some of its magnetic field lines will return through the element itself, thus reducing the measurable magnetic field outside the element. Pie-shaped pieces 121 with any magnetization direction have no symmetry with respect to their magnetization direction. This breaking of symmetry means that pieces with different magnetization directions and not touching as shown in FIG. 2b will show a large difference in the magnetic flux density between their inside and outside. As a result, pieces with different magnetization directions and not touching as shown in FIG. 2b will not show similar maximum magnetic field strengths. However, if all pie-shaped elements of a Halbach array have the same residual magnetic field B remIf the magnetic poles are magnetized uniformly and in contact with each other as shown in FIG. 2b, the assembled system can be made to very closely approximate the ideal magnetic field configuration given by Equations 1 and 2.

[0090] In one embodiment, an array for use in a rotating machine includes a plurality of similar discrete magnetic segments. When the segments are spaced apart, such as before being arranged in the array, each segment includes magnetic poles with the same maximum magnetic field strength. Flux channeling can be achieved when the segments are (i) formed into a circumferential array having a rotating magnetic field in sequence along the array, and (ii) each segment is positioned close enough to the adjacent segment in sequence along the array such that the magnetic fields interact with each other. In various embodiments of the invention, to produce magnetic flux channeling, the segments may be in physical contact with each other or may be spaced apart close enough such that the magnetic fields between adjacent segments in the array interact with each other to produce magnetic flux channeling.

[0091] Although the invention has been described with reference to specific embodiments, those skilled in the art will recognize that various modifications can be made and elements thereof substituted with equivalents without departing from the scope of the invention.

Claims

1. 1. A magnetic system suitable for use in a rotating machine or gearbox, comprising at least a first array structure extending along a central axis including at least a first plurality of similar discrete magnetic segments, each segment of the first plurality of segments having: (i) having an elongate length relative to its width and extending along its major sides in a direction parallel to said central axis; (ii) contain magnetic poles having similar characteristic magnetic field distributions, including maximum magnetic field strength directions and the same maximum magnetic field strengths; (iii) a surface having a cross-sectional shape with the direction of maximum magnetic field strength facing outwardly of the surface, the segments being rotatable about an axis about the surface prior to fixed placement of each segment in a first array of similar magnetic segments arranged circumferentially about the central axis; (iv) a major side surface of the first plurality of segments is fixedly positioned to extend along a direction parallel to the major side surfaces of the other segments of the first plurality of segments; and (v) disposing the magnetic segments in a direction parallel to the central axis and combining with other segments of the first plurality of segments to integrally form a first array of similar magnetic segments, the first array being configured as the first ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position within the first ordered sequence, resulting in a shift in angular orientation of the magnetic poles between the magnetic segments of the first ordered sequence; Magnetic system.

2. 2. The magnetic system of claim 1, wherein the first plurality of segments are positioned in contact with or sufficiently close to one or more other segments to additively combine or reduce magnetic fields from different segments, thereby providing a net magnetic field strength for the first array structure, where the magnetic field strength is increased on one of the inner or outer circumference sides of the first array while the magnetic field strength is decreased on the other of the inner or outer circumference sides of the first array.

3. 2. The magnetic system of claim 1, wherein the magnetic segments are arranged in a sequential order and the magnetic segments are rotated about an axis relative to other magnetic segments to sequentially shift the orientation of the maximum magnetic field strength direction characteristic of the segments, thereby resulting in the increased magnetic field strength on one side of the first array.

4. 2. The magnetic system of claim 1, further comprising a support structure that causes the first plurality of magnetic segments to occupy fixed positions relative to the central axis and each other and fixes the relative shift in orientation of the characteristic maximum magnetic field strength direction between the magnetic poles.

5. The magnetic system of claim 4 , wherein the support structure includes a series of channels or recesses in which the magnetic segments are disposed.

6. 6. The magnetic system of claim 5, wherein the magnetic segments and the channels or recesses have complementary shapes or mating features that lock the rotational position of the segments and fix the relative shift in magnetic field direction in place.

7. 2. The magnetic system of claim 1 further comprising a support structure having a series of openings therein formed along said central axis, said first plurality of discrete magnetic segments being rotated about an axis and disposed within said openings to sequentially provide said shift along said first array.

8. The magnetic system of claim 7, wherein the support structure includes a series of pressed laminates joined together, the pressed laminates including a non-magnetic material.

9. and a second array structure extending along said central axis including at least a second plurality of similar discrete magnetic segments, each segment of said second plurality of segments having: (i) having an elongate length relative to its width and extending along its major sides in a direction parallel to said central axis; (ii) contain magnetic poles having similar characteristic magnetic field distributions, including maximum magnetic field strength directions and the same maximum magnetic field strengths; (iii) having a surface having a cross-sectional shape with said maximum magnetic field strength direction facing outwardly from said surface, said segment being axially rotatable about said surface prior to fixed placement of said segment in a second array of similar magnetic segments circumferentially arranged about said central axis; (iv) a major side surface of the first plurality of segments is fixedly positioned to extend in a direction parallel to the major side surfaces of other segments of the first plurality of segments; and 2. The magnetic system of claim 1, wherein: (v) segments of the second plurality of segments are arranged to extend in a direction parallel to the central axis and combine with other segments of the second plurality of segments to integrally form the second array of similar magnetic segments, the second array being configured as the second ordered sequence having magnetic poles of the magnetic segments that rotate relative to one another as a function of position in the second ordered sequence, resulting in a shift in angular orientation of the magnetic poles between the magnetic segments in the second ordered sequence.

10. The magnetic system of claim 9, wherein the second array of magnetic segments is configured to provide a sequence of elements including a rotationally shifted angular orientation of a magnetic field pattern, the angular orientation of the magnetic field pattern rotating in a direction perpendicular to the central axis between different magnetic elements.

11. 2. The magnetic system of claim 1, wherein the spatial rotation of the magnetic field pattern configures magnetic flux in such a way as to provide an increased magnetic field strength on one of an inner or outer circumferential side of the first array, while providing a decreased magnetic field strength on the other of the inner or outer circumferential side of the first array.

12. 2. The magnetic system of claim 1, wherein the first array includes n magnetic segments, and the magnetic field pattern between each one of the n segments is characterized by a rotational shift in the angular orientation relative to the angular orientation of the magnetic field pattern of an adjacent element in the sequence.

13. 10. The magnetic system of claim 9, wherein the second array includes m magnetic segments, and the magnetic field pattern between each one of the m segments is characterized by a rotational shift in the angular orientation relative to the angular orientation of the magnetic field pattern of an adjacent element in the sequence.

14. 2. The magnetic system of claim 1, wherein the first array includes n magnetic segments, and a magnetic field pattern between less than n ones of the n magnetic segments is characterized by a rotational shift in the angular orientation relative to the angular orientation of the magnetic field pattern of an adjacent element in the sequence.

15. 10. The magnetic system of claim 1, wherein the flux directing inner back core is mechanically coupled to rotate synchronously with the rotor to avoid, reduce or eliminate the presence of changing magnetic fields that would cause magnetization in the inner back core.

16. 10. The magnetic system of claim 1 further comprising a circumferential array between said first array and said second array, said circumferential array including ferromagnetic segments disposed in coaxial alignment with each of said arrays.

17. 1. A magnetic array for use in a synchronous electric machine or a magnetic gearbox, the magnetic array comprising a plurality of discrete magnetic segments; when each of said magnetic segments is positioned away from the influence of ferromagnetic material, such as before being placed in an array, each magnetic segment includes a magnetic pole having the same maximum magnetic field strength; each magnetic segment is arranged in a sequence along the circumferential array with a change in magnetic field direction, whereby the magnetic field of each magnetic segment is spatially rotated with respect to the magnetic fields of adjacent segments in the sequence; each magnetic segment is positioned sufficiently close to its neighbor in the sequence such that the magnetic fields interact with each other to provide magnetic flux channeling, and each magnetic segment is in physical contact with or spaced apart from its neighbor in the sequence such that interaction of the magnetic fields between adjacent magnetic segments in the array provides magnetic flux channeling; Magnetic array.

18. A magnetic array as described in claim 17, wherein each magnetic segment in the magnetic array is spaced from an adjacent magnetic segment in the sequence while being positioned sufficiently close together so that the magnetic fields between adjacent spaced magnetic segments in the array interact to provide magnetic flux channeling.

19. A magnetic array arranged in a magnetic system according to claim 1 including a synchronous electric machine or a magnetic gearbox, A frame disposed along the central axis; a shaft connected for rotation with respect to the frame and extending in a first direction through the central axis; a magnetic field generating rotor and a stator each disposed concentrically about the shaft and extending in a direction along the frame such that each is coaxial with the other about the central axis, the stator being fixedly attached to the frame and the magnetic field generating rotor being attached to the frame such that it rotates relative to the frame and the stator; the magnetic field generating rotor and the stator each have a circumferential surface extending along the central axis, one of the magnetic field generating rotor or the stator including the first array structure therein, each segment of the first plurality of segments being positioned sufficiently close to an adjacent segment in the sequence such that magnetic fields interact with each other to effect magnetic flux channeling; Magnetic array.

20. Each segment of the first plurality of segments is positioned sufficiently close to its adjacent segment in the sequence that the magnetic fields interact with each other to provide sufficient magnetic flux channeling and eliminate the need for bending of magnetic field lines by placing a back core as a shield around the frame to provide a return path for the magnetic flux of the field generating rotor.

20. The magnetic array of claim 19.

21. A magnetic array as described in claim 19, wherein the magnetic field generating rotor includes the first array structure, the stator includes windings, and the magnetic system further includes a back core arranged coaxially with the magnetic field generating rotor radially outward from the magnetic segments in the first array structure of the magnetic field generating rotor, the windings of the stator extending along an air gap between the magnetic field generating rotor and the back core to generate an increased radial magnetic flux density in the air gap.

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