Synchronous reluctance motor with 3D printed rotor

Abstract

A synchronous reluctance machine includes a stator having stator teeth and windings disposed radially symmetrically about a central axis. The windings are oriented to set an annular wire set about a central axis. And each winding is arranged between two adjacent stator teeth. The first rotor is provided on a first stator side of the stator. The first rotor is rotatable relative to the stator about a central axis. The first rotor includes a first rotor core disposed radially symmetrically about the central axis. Each first rotor core includes: a first proximal surface facing the winding; and a plurality of first magnetic flux paths. The first magnetic flux paths may be defined by first magnetic barriers interlaced with the first magnetic flux paths, wherein each first magnetic flux path has two ends adjacent a first proximal surface, respectively.

Description

Related applications

[0001] This application claims the benefit of priority to Singapore application No. 10202300384W filed on February 16, 2023, the contents of which are incorporated herein by reference in their entirety for all purposes. Technical Field

[0002] The present application relates to electric machines, and more particularly to synchronous reluctance motors. Background Art

[0003] There is a need for motors that are more sustainable and have performance comparable to conventional permanent magnet motors (e.g., permanent magnet-free motors). Conventional synchronous reluctance motors are expected to be a promising permanent magnet-free alternative to conventional permanent magnet motors (especially conventional motors using rare earth magnet materials), but they have several technical limitations. It is well known that the setting of the rotor magnetic barriers determines the salient pole ratio (SPR). The larger the SPR, the greater the torque of the synchronous reluctance motor. However, the magnetic bridge used to provide the necessary mechanical strength of the rotor will degrade the SPR and, in turn, have a negative impact on the torque capacity of the synchronous reluctance motor. This limitation is inevitable in conventional synchronous reluctance motors with rotors made of sheet lamination. In addition, in order to obtain a higher SPR at a lower number of pole pairs, overlapping distributed wire groups must be used. The wire groups have larger wire group ends that reduce the overall torque density of the motor. Therefore, conventional synchronous reluctance motors still lag behind permanent magnet motors in terms of torque density, power factor, and efficiency. Summary of the Invention

[0004] In one aspect, the present application discloses a synchronous reluctance motor having a stator and a first rotor. The stator has a first stator side and a second stator side opposite the first stator side. The stator includes: a plurality of stator teeth arranged radially symmetrically about a central axis; and a plurality of windings arranged radially symmetrically about the central axis. The plurality of windings are oriented to define a ring-shaped wire group about the central axis. Each winding is respectively arranged between two adjacent stator teeth. A first rotor is arranged on the first stator side. The first rotor is rotatable relative to the stator about the central axis. The first rotor includes: a plurality of first rotor cores arranged radially symmetrically about the central axis. Each first rotor core includes: a first proximal surface facing the winding; and a plurality of first magnetic flux paths. The plurality of first magnetic flux paths can be defined by a plurality of first magnetic barriers interlaced with the plurality of first magnetic flux paths, wherein each of the plurality of first magnetic flux paths has two ends adjacent to the first proximal surface.

[0005] The synchronous reluctance motor may also be configured to form an axial magnetic flux in response to current in a selected winding. The axial magnetic flux may include a plurality of axially extending segments parallel to the central axis and a plurality of curved segments corresponding to the plurality of first flux barriers.

[0006] On the other hand, the synchronous reluctance motor may further include: a second rotor. The second rotor may be disposed on the second stator side, wherein the second rotor is rotatable relative to the stator about a central axis. The second rotor includes: a plurality of second rotor cores disposed radially symmetrically about the central axis. Each second rotor core may include: a second proximal end surface facing the winding; and a plurality of second magnetic flux paths. The plurality of second magnetic flux paths may be defined by a plurality of second magnetic barriers interlaced with the plurality of second magnetic flux paths, wherein each of the plurality of second magnetic flux paths has two ends adjacent to the second proximal end surface.

[0007] The first proximal surface and the second proximal surface may be disposed in opposite directions facing each other.

[0008] During operation, an axial magnetic flux can be formed, which includes: a plurality of first curved magnetic flux paths corresponding to the plurality of first magnetic flux paths of the first rotor core; a plurality of second curved magnetic flux paths corresponding to the plurality of second magnetic flux paths of the second rotor core; and a plurality of axially oriented magnetic flux paths extending between the plurality of first curved segments and the plurality of second curved segments, the plurality of axially oriented magnetic flux paths being parallel to the central axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various embodiments of the present application will be described with reference to the following drawings:

[0010] Figure 1 is a perspective view of a motor according to an embodiment of the present application;

[0011] Figure 2 yes Figure 1 Exploded view of the motor shown;

[0012] Figure 3A yes Figure 2 a diagram of the retaining ring shown;

[0013] Figure 3B Here is an image of the retaining ring of the prototype device;

[0014] Figure 4A Shown is the stator as viewed from one side. Figure 2 The stator shown;

[0015] Figure 4B is an image of a stator of a prototype device according to an embodiment of the present application;

[0016] Figure 5A is an image of the stator segment;

[0017] Figure 5B is the image of the stator teeth;

[0018] Figure 5C is an image of the stator yoke;

[0019] Figure 5D is the image of the winding;

[0020] Figure 6A is a perspective view of a stator tooth with windings according to an embodiment of the present application;

[0021] Figure 6B yes Figure 6A Exploded views of the components shown;

[0022] Figure 7A is an image of a rotor housing according to some embodiments;

[0023] Figure 7B yes Figure 7A An image of a rotor housing is shown with the rotor core disposed within a housing cavity;

[0024] Figure 8A is a perspective image of the constructed rotor core;

[0025] Figure 8B yes Figure 8A A top view image of the rotor core shown;

[0026] Figure 8C is a perspective view of a rotor core according to an embodiment of the present application;

[0027] Figure 8D yes Figure 8C a cross-sectional view of the rotor core shown;

[0028] Figure 9 yes Figure 1 A partial cross-sectional view of the motor shown;

[0029] Figure 10A yes Figure 9 A schematic diagram of the magnetic flux distribution in the rotor core is shown;

[0030] Figure 10B is a diagram showing a magnetic flux distribution in a circumferential cross-sectional view;

[0031] Figure 10C(i) to Figure 10C(iv) are schematic diagrams showing different example structures for the proposed motor;

[0032] Figure 11 It is for Figure 1 Illustration of the 2D model proposed for the simulation study of the motor shown;

[0033] Figure 12is the magnetic induction intensity (B)-magnetic field intensity (H) curve (BH curve) of the prototype rotor core;

[0034] Figure 13 It shows that the available Figure 12 Graphical representation of the torque achieved by the prototype rotor shown;

[0035] Figure 14 is a diagram of preferred geometric parameters of a flux barrier for an exemplary motor of the present application;

[0036] Figure 15 Shows the BH curves of the 3D printed core before and after annealing;

[0037] Figure 16 Show Figure 15 The waveform of the rated torque of the motor shown;

[0038] Figure 17 Show Figure 16 Performance test results of the prototype device shown;

[0039] Figure 18 It is a schematic diagram of the alternative magnetic barrier setup;

[0040] Figure 19 It is a schematic diagram of another alternative magnetic barrier setup;

[0041] Figure 20 It is a schematic diagram of another alternative magnetic barrier setup;

[0042] Figure 21 It is a schematic diagram of another alternative magnetic barrier setup;

[0043] Figure 22 Showing Model-S, Model-L and Model-P of the proposed 3D printed rotor core;

[0044] Figure 23 A method for developing Model-P for selective laser melting is shown;

[0045] Figure 24 is a comparison chart of the mechanical properties of the proposed rotor core and the conventional rotor. DETAILED DESCRIPTION

[0046] The following detailed description will be made with reference to the accompanying drawings, which show details and embodiments of the present application for illustrative purposes. Features described in the context of one embodiment may also apply to the same or similar features in other embodiments, even if not explicitly described in those other embodiments. Applications, combinations, and / or substitutions described in the context of one embodiment may also apply to the same or similar features in other embodiments.

[0047] In the context of various embodiments, the articles “a,” “an,” and “the” used with respect to features or elements include reference to one or more features or elements.

[0048] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0049] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any "exemplary" embodiment described herein is not necessarily to be construed as preferred or advantageous over other embodiments. As used herein, the singular "a," "an," and "an" should be understood to include the plural "one or more" unless the context clearly dictates otherwise.

[0050] Terms such as "first" and "second" are used in the description and claims for simplicity and clarity only and do not necessarily indicate priority or order unless the context requires otherwise.

[0051] The terms "about" and "approximately" as applied to stated numerical values ​​encompass the exact value and reasonable differences that would be understood by one of ordinary skill in the art, and the terms "generally" and "substantially" should be interpreted in a similar manner unless otherwise indicated.

[0052] Motor Components Overview

[0053] Figure 1 1 is a perspective view of a synchronous reluctance motor (SynRM) 100 according to an embodiment of the present application. SynRM 100 includes a stator 200 and a rotor 600, which are assembled in alignment with a central axis 101, with rotor 600 disposed to one side of stator 200. Central axis 101 can be defined by the rotational symmetry axis of SynRM 100. For simplicity, references to an "axial direction" or similar terms in this application will be understood to mean parallel to or substantially parallel to central axis 101.

[0054] The rotor 600 and stator 200 are axially aligned along the central axis 101, rather than being concentrically arranged. During operation, the air gap between the rotor 600 and the stator 200 is parallel to the axial direction. For this reason, the SynRM 100 presented herein can be interchangeably referred to as an axial flux synchronous reluctance motor (AF SynRM).

[0055] In various embodiments, the SynRM 100 includes two rotors 600 (e.g., a first rotor 601 and a second rotor 602 ), respectively disposed on either side of the stator 200 . Each rotor 600 is rotatable relative to the stator 200 about the central axis 101 . Each rotor 600 includes a rotor core 800 , which defines a magnetic flux barrier 870 . The stator 200 includes stator teeth 400 and windings 500 , forming an annular coil system distributed in a circular / circumferential direction about the central axis 101 . During operation, the first rotor 601 , the second rotor 602 , and the stator 200 collectively define a three-dimensional (3D) axial magnetic flux.

[0056] In practice, manufacturing the proposed rotor 600 using conventional methods, such as laminating sheets, is extremely challenging (or even practically impossible). A test prototype of the proposed rotor 600 was successfully fabricated using 3D printing or additive manufacturing techniques. Therefore, the various embodiments of the proposed SynRM 100 can be interchangeably referred to as 3D-printed axial flux synchronous reluctance motors (3DF-AF SynRMs).

[0057] Figure 2 Shown is a diagram exploded along the central axis 101. Figure 1 The SynRM100 shown is used to more clearly illustrate the various components of SynRM100.

[0058] In some examples, the SynRM 100 may include a segmented stator 200 or a stator 200 comprised of a plurality of stator segments 210. In some examples, the stator 200 includes a retaining ring 300 coupled to the plurality of stator segments 210. Each stator segment 210 includes stator teeth 400, a stator yoke 450, and a winding 500. Each stator segment 210 may be coupled to the retaining ring 300 independently of or relatively independently of the other stator segments 210. The winding group in the present SynRM 100 may be described as a ring-shaped winding group 510, such as Figure 2 The annular wire group 510 is arranged relative to the stator teeth 400 and the rotor 600 to form a 3D axial magnetic flux, for example, a 3D flux path pattern including a magnetic flux path passing through the stator-rotor air gap in the axial direction.

[0059] In some examples, rotor 600 includes a rotor core 800. Rotor 600 may include a rotor housing 700 having a plurality of rotor cores 800 disposed therein.

[0060] In some examples, the SynRM 100 may include a double-sided rotor 600, such as two rotors 600 on either side of the stator 200. For example, the first rotor 601 may include a plurality of first rotor cores 801 disposed in a first rotor housing 701, and the second rotor 602 may include a plurality of second rotor cores 802 disposed in a second rotor housing 702. The first rotor 601 may be disposed on the first stator side 211 of the stator 200, and the second rotor 602 may be disposed on the second stator side 212 of the stator 200. This dual-rotor structure advantageously provides better torque and axial force balance while using only one set of annular wire groups 510.

[0061] The various components of the SynRM 100 of the present application will be further described below to facilitate understanding.

[0062] stator

[0063] Figure 3A The fixing ring 300 of the stator is shown. Figure 3B An image showing a retaining ring 300 of a prototype device of the proposed SynRM 100 is shown. Retaining ring 300 can be a closed loop. A plurality of retaining projections 310 are distributed along the inner circumferential surface 301 of the closed loop, for example, in radial symmetry with respect to the geometric center of retaining ring 300. Each retaining projection 310 can be coupled to a corresponding stator tooth.

[0064] The stator may be described as having two opposing annular stator sides, such as a first stator side and a second stator side. Figure 4A A schematic diagram of a SynRM100 stator 200 is shown, viewed from one stator side. Figure 4B is an image of stator 200 showing stator segments 210 according to an embodiment of the present invention. During assembly, stator 200 can be described as having radial symmetry about a central axis. Stator 200 includes a plurality of stator teeth 400 arranged radially symmetrically about the central axis. Stator 200 can be described as a segmented stator or an assembly of stator segments 210. The number of stator segments 210 in stator 200 can vary depending on the embodiment.

[0065] The stator 200 further includes a plurality of windings 500 arranged radially symmetrically about the central axis. Each winding 500 is disposed between two adjacent stator teeth 400. Each winding 500 is substantially wound around the stator yoke, with the ends of the windings extending from between adjacent stator teeth 400.

[0066] Figure 5A is an image of stator segment 210 . Figure 5B is an image of stator teeth 400 . Figure 5C is an image of the stator yoke 450 . Figure 5D is an image of the winding 500 . Figure 6A and Figure 6B A schematic diagram of the stator components is shown in FIG to better illustrate the details. Specifically, Figure 6A A close-up view of two stator teeth 400 and a winding 500 disposed therebetween is shown, and Figure 6B Shown is a diagram exploded along the tangential axis 103. Figure 6A Parts shown.

[0067] In this example, each stator tooth 400 has two opposite main surfaces 401 and 402. During assembly, two adjacent stator teeth 400 in the plurality of stator teeth 400 are arranged side by side, such as Figure 6A 4 , wherein the respective major surfaces 401, 402 of adjacent stator teeth 400 collectively define a slot 410 therebetween. One or more windings 500 may be disposed in the slots 410, wherein their winding planes 510 are substantially parallel to the major surfaces 401, 402 of adjacent stator teeth 400. The winding plane 510 may be defined by a surface of the winding 500 that is perpendicular or substantially perpendicular to the tangential axis 103.

[0068] The winding 500 may be formed with a winding width approximately equal to or slightly larger than the slot width (the distance between the opposing major surfaces 401 , 402 of adjacent stator teeth 400 ). The winding 500 may be formed with a winding height determined by the height of the stator teeth 400 .

[0069] The winding 500 may include a plurality of turns or coils of wire forming a ring having a winding inner peripheral edge 521 and a winding outer peripheral edge 522. The stator yoke 450 may be sized and shaped to complement the winding 500. Alternatively, the winding inner peripheral edge 521 may be shaped and sized to be relatively close to the size and shape of the stator yoke 450.

[0070] The stator teeth 400 may be provided with flanges 430 (also referred to as stator tooth ends 430). The stator tooth ends 430 of adjacent stator teeth 400 are spaced apart to define a slot opening (slot opening) that is smaller than the slot width (the width of the slot 410). )420. To obtain a relatively constant and small notch ( ), the slot filling rate may vary from embodiment to embodiment.

[0071] By adjusting the winding width and / or winding height relative to the dimensions of the stator teeth 400 and / or the dimensions of the stator yoke 450, the stator of the present SynRM 100 can achieve a relatively high slot fill ratio (e.g., a slot fill ratio in the range of 80%). The slot fill ratio refers to the proportion or portion of the space / air between adjacent stator teeth 400 that is occupied by the windings 500 and / or the stator yoke 450.

[0072] See also Figure 2The modular or segmented configuration of the stator 200 proposed herein additionally and advantageously enables prefabrication of the annular windings 510. Generally speaking, the plurality of windings 500 are oriented to define the annular windings 510 about the central axis 101. However, each stator segment 210 can be assembled separately. For example, the stator segments 210 can be prefabricated by coupling the stator teeth 400 to the stator yoke 450, e.g., wherein the stator yoke 450 extends from the major surfaces 401 / 402 of the stator teeth 400. The windings 500 can be wound in a separate step so that the wound windings 500 can be attached to the stator yoke 450 (rather than being wound in situ around the stator yoke 450). Each winding 500 can be arranged around the stator yoke 450 independently of the other stator segments 210. When assembled together and coupled to the retaining ring 300 , the plurality of stator segments 210 form a circular assembly with the windings 500 oriented to define an annular body of wire groups, ie, a set of annular wire groups 510 .

[0073] Advantageously, the annular coil group 510 proposed herein can be assembled more efficiently than conventional overlapping coil groups. The annular coil group 510 is at least partially achieved by a segmented stator arrangement. Compared to conventional motors, the slot fill rate of the present SynRM 100 in various embodiments can exceed 40% or more. Thermal conductivity is significantly improved, and coil group ends are significantly reduced. Compared to conventional SynRMs, the proposed SynRM 100 can have improved electrical load capacity and higher torque density. Testing of the proposed annular coil group (using a permanent magnet rotor) further demonstrated good cooling capabilities (e.g., at 5 The temperature rise is less than 5℃ within 10 minutes).

[0074] Due to the large geometric radius, high utilization of the double-sided magnetic flux field, and the large geometric radius, the axial flux dual-rotor structure in various preferred embodiments further achieves higher torque density. In some embodiments, the use of annular coils can achieve slot fill rates up to 80%, with smaller coil ends and improved heat dissipation, representing a significant improvement over conventional motors with overlapping coils. The effective torque density of the SynRM100 is accordingly higher than that achievable with conventional approaches.

[0075] rotor

[0076] Figure 7A is an image of the rotor housing 700, and Figure 7B FIG is an image of a rotor housing 700 having a rotor core 800 disposed in a housing cavity 730. The rotor core 800 may be secured by a pair of mounting pins 708 that couple to mounting holes 807 of the rotor core 800 (see FIG. Figure 8C ). See also Figure 1 and Figure 2Each rotor 600 may be comprised of a plurality of rotor cores 800 disposed within a rotor housing 700. The rotor housing 700 may be an annular plate 710 having an inner circumferential wall 721 and an outer circumferential wall 722. The rotor housing 700 includes one or more housing cavities 730 to accommodate the respective rotor cores 800. In this example, the inner circumferential wall 721 has a circular profile, and the outer circumferential wall 722 has a polygonal profile. The polygonal profile facilitates easy positioning and orientation of the plurality of rotor cores 800 within the rotor housing 700. During assembly, each rotor core 800 has an inner surface 821 that abuts or contacts the inner circumferential wall 721 of the rotor housing 700. During assembly, each rotor core 800 has an outer surface 822 that abuts or contacts the outer circumferential wall 722 of the rotor housing 700. Each rotor core 800 is assembled with the rotor housing 700 with its proximal end surface 841 facing the stator 200 or winding 500. Each rotor core 800 has a distal surface 842 opposite the proximal surface 841. Each rotor core 800 is housed in a corresponding position within the housing cavity 730, with the distal surface 842 in contact with the annular plate 710. The proposed arrangement, which allows multiple rotor cores 800 to be individually mounted on the rotor housing 700, facilitates the manufacture of the proposed rotor 600. The subassembly of the rotor core 800 and the rotor housing 700 can then be easily connected to other mechanical components of the SynRM 100, such as shafts, bearings, etc.

[0077] In the example shown, the SynRM 100 is an 8-pole configuration. Eight rotor cores 800 together form the rotor 600. Each rotor core 800 spans 45 degrees, or one-eighth of the rotor 600. Figure 8A and Figure 8B is an image of rotor core 800 constructed via additive manufacturing techniques. Figure 8C A close-up view of the rotor core 800 is shown, and Figure 8D A cross-sectional perspective view of a portion of rotor core 800 is shown.

[0078] Each rotor core 800 can be described as having a generally trapezoidal shape. The rotor core 800 can include an inner surface 821 and an outer surface 822. The inner surface 821 and the outer surface 822 face away from each other. The inner surface 821 of the rotor core 800 can be a curved surface or an inner concave surface complementary to a section of the inner circumferential wall 721 of the rotor housing 700. The outer surface 822 of the rotor core 800 can be a flat surface or a planar surface complementary to a section of the outer circumferential wall 722 of the rotor housing 700.

[0079] The rotor core 800 further includes a proximal surface 841 that is orthogonal to the inner surface 821 and the outer surface 822. The rotor core 800 may further include a distal surface 842 that is opposite the proximal surface. During assembly, the proximal surface 841 is positioned adjacent to the stator 200 so that the axially oriented magnetic flux path extending from the stator 200 passes through the proximal surface 841. During assembly with the rotor housing 700 (see FIG. 1 ), the rotor core 800 further includes a distal surface 842 that is opposite to the proximal surface. Figure 7B ), the rotor core 800 can be locked to the rotor housing 700 by engaging the mounting pins 708 with the corresponding mounting holes 807. The air gap (surface-to-air gap 160) between the rotor 600 and the stator 200 is an axially oriented spacing defined by the proximal surface 841 and the stator tooth tips 430.

[0080] The rotor core 800 may include a body of a first material, with a plurality of layers 850 or a plurality of magnetic flux paths 150 defined therein. For example, the rotor core 800 may include a plurality of magnetic flux paths 150 defined therein by a corresponding plurality of magnetic barriers 870. The magnetic flux paths 150 may correspond to the layers 850 of the first material, wherein the magnetic reluctance of the first material is lower than the reluctance of the magnetic barriers 870. In some examples, the first material or the rotor core may be made of silicon steel (Si-Fe). In some examples, the magnetic barriers 870 may include a second material having a higher reluctance than the first material.

[0081] In some examples, flux barrier 870 can be an air gap. In the proposed rotor core 800, providing a flux bridge in one or more flux barriers is optional. A flux bridge refers to a connection that bridges a magnetic flux path or air gap, as is known in the art. In some embodiments, due to the axial flux topology formed in the proposed SynRM 100, rotor core 800 does not require a flux bridge to provide additional mechanical strength and accordingly has a relatively high salient pole ratio.

[0082] In different embodiments, the rotor core 800 may be configured differently, for example, a different number of magnetic flux paths 150 (or layers 850) may be included in one rotor core 800. In this example, for illustration only and not limitation, the rotor core 800 shown includes six magnetic flux paths 150 (or six layers 850) defined by five 3D flux barriers 870.

[0083] The rotor core 800 proposed herein, with its 3D magnetic flux path and magnetic barrier configuration, is extremely challenging to manufacture using conventional sheet lamination methods. The rotor core 800 can be additively manufactured or 3D printed along a build direction 108 perpendicular to the outer surface 822 of the rotor core 800. For example, the rotor core 800 can be additively built starting from the outer surface 822 and continuing to the inner surface 821. Various 3D printers can be used. In this example, a TruPrint 1000 3D printer (available from TRUMPF SE + Co. KG) equipped with two 200 W TRUMPF fiber lasers (wavelength: 1070 nm, laser beam spot size: 30 μm) was used.

[0084] Figure 9 yes Figure 1 A partial cross-sectional view 100 ′ of a SynRM 100 is shown, and more specifically, a partial model of the proposed SynRM 100 having 12 stator slots and a single-sided 1-pole-pair rotor. Figure 10A and Figure 10B Additionally shown Figure 9 A schematic diagram of magnetic flux path 150 in rotor core 800 is shown. Magnetic flux path 150 passes through the air gap from stator 200 to rotor 600 and enters rotor core 800 through the proximal surface. Within rotor core 800, magnetic flux path 150 is guided by magnetic barriers 850 to form a bend (curved segment) and then returns to stator 200 through proximal surface 841. A series of two-dimensional (2D) linear models 900 or circumferential cross-sectional views of rotor core 800 taken at different radial positions show that the magnetic flux distribution in rotor core 800 is three-dimensional (3D), i.e., the magnetic flux distribution varies radially and circumferentially.

[0085] The plurality of flux barriers 870 include openings 872 extending from the (circumferential) inner wall 821 of the annular rotor to the (circumferential) outer wall 822 of the annular rotor. The openings 872 may have different shapes and sizes in different embodiments.

[0086] In a dual-rotor SynRM, two rotors are provided, one on each stator side of the stator. The magnetic flux path distribution in the two rotors is preferably arranged to be mirror-symmetrical about the mid-plane of the SynRM.

[0087] like Figure 10C(i) to Figure 10C(iv)As shown, structurally, the proposed SynRM100 can adopt a variety of configurations. FIG10C(i) schematically illustrates a single air gap configuration. FIG10C(ii) schematically illustrates a double air gap, double rotor configuration. FIG10C(iii) schematically illustrates a double air gap, double stator configuration. FIG10C(iv) schematically illustrates an example of a multiple air gap configuration. In other words, different embodiments of the proposed motor can be configured differently, for example, in terms of the number of air gaps, the number of rotors and stators, the relative positions of the rotor / stator / air gap, etc.

[0088] Advantageously, the proposed motor can be constructed with a double air gap to enhance material and space utilization, obtain a more balanced axial force (e.g., a more balanced axial force obtained due to a symmetrical structure), and achieve a relatively simple manufacturing and assembly process (compared to other conventional single air gap and multi-air gap motors).

[0089] Different configurations are possible for the proposed annular winding arrangement. Using slots to distribute the windings and reducing the overhang can achieve a relatively high winding factor.

[0090] 2D linear modeling

[0091] Although the magnetic flux paths in rotor core 800 have a three-dimensional (3D) distribution in Cartesian coordinates, if radial magnetic flux paths are ignored, the magnetic flux paths in rotor core 800 can be considered as a two-dimensional (2D) distribution within the circumferential surface area. Figure 11 The manner in which the three-dimensional model of the proposed SynRM 100 can be approximated as a series of two-dimensional linear models 900 with symmetric and periodic magnetic fields is shown in graphical form. Figure 11 As shown in the series of two-dimensional linear models (901, 902, 903, 904, 905), it can be seen that the rotor core 800 is at different radial positions (e.g. ) shows that the shapes of the magnetic barriers and the corresponding magnetic flux paths are different at different radial positions.

[0092] Different embodiments of the proposed SynRM 100 can be configured with different geometric parameters. In some examples, different conditions can be considered to determine a preferred set of parameters. The conditions can include defining the outline or shape of each magnetic barrier as a semi-ellipse. The geometric expression of an ellipse can be followed.

[0093] The condition may include defining a three-dimensional shape for each magnetic barrier based on two sets of elliptical curves. For example, the innermost radial circumferential surface of the magnetic barrier may be defined by one elliptical curve, and the outermost radial circumferential surface of the magnetic barrier may be defined by another elliptical curve.

[0094] The condition may include defining an intra-rotor outline of the flux barrier, connecting the two contoured surfaces, as a linearly varying function.

[0095] Example 1

[0096] In one example, the proposed SynRM100 is provided with a three-dimensional magnetic flux distribution that changes in the radial direction while presenting a two-dimensional flux path in the circumferential direction of the motor. A two-dimensional model can be defined as a series of two-dimensional linear models with symmetrical and periodic magnetic fields.

[0097] In this example, a motor unit of the proposed SynRM100 having 12 slots and two poles in one quadrant (90 mechanical degrees) is divided into units with similar stack lengths. The five two-dimensional linear models are divided based on the following calculation formulas (1) to (4):

[0098] The torque of SynRM100 can be obtained from the following formula (5), where Defined as the force generated by each 2D linear model separately:

[0099] Geometric parameters can be adjusted (e.g., optimized) to achieve a desired torque (e.g., maximum torque). Different two-dimensional linear models can be characterized by different parameters or parameter values. For example, some parameter conditions can be applied to simplify the rotor structure and / or account for manufacturing factors, such as the printing capabilities of additive manufacturing tools used to 3D print the rotor.

[0100] Table 1 lists some motor parameters of the proposed SynRM100 according to this example, for illustrative purposes only and not limiting. A 3D finite element analysis model with the same parameters was constructed, and its performance was simulated. Table 2 compares the performance based on a series of 2D linear models and 3D models. The comparison results show a small difference or deviation of only 4.7% in the rated load output torque. These results validate the feasibility or effectiveness of using 2D linear models for simulation instead of 3D models. Table 3 lists other electromagnetic performance of the SynRM100 according to this example.

[0101] Figure 12 Figure 1 shows a BH curve obtained from a prototype device used to test the additively manufactured rotor core for this example. The tests verified that the magnetic properties of the prototype rotor core meet multiple standards, including international standards (such as IEC 60404-2, IEC 60404-3, and IEC 60404-6) and national standards (such as GB / T 3655-2008, GB / T 13789-2008, GB / T 3658-2008, and GB / T 19346.1-2017).

[0102] In the proposed axial flux arrangement, the orthotropic position of the flux barrier axis relative to the direction of rotation beneficially means that the rotor core is not subjected to significant mechanical stresses that could lead to core fracture. Unlike conventional rotors, which require magnetic bridges in the flux barrier to provide the necessary mechanical or structural strength, in the proposed SynRM100, magnetic bridges are not required (or optional). The proposed SynRM100 can be manufactured with a relatively high saliency ratio and the potential for high output torque.

[0103] Additionally, in the double-sided rotor arrangement of this example using annular windings, the torque can be essentially doubled without requiring higher currents. Figure 13 Figure 2 is a graph showing the torque of this example motor. This example of the proposed SynRM100 has a volume of 0.64L and is capable of delivering an average torque of 2.13Nm and a torque density of 3.36Nm / L. This performance makes the proposed SynRM100 a viable option for gearless direct-drive motor applications and expands the range of viable applications for synchronous reluctance motors.

[0104] Example 2

[0105] To facilitate understanding, a method for determining various geometric parameters of the magnetic barrier will be described with reference to a second example of the present motor. For the purpose of 3D printing, the representation describing the magnetic barrier geometry can be converted into a printable model, as will be further described below.

[0106] The present invention's two-sided SynRM, with 48 slots and eight poles, is simplified to a single-sided quadrant unit model (e.g., a 1 / 8th model) with 12 slots and two poles. The simplified three-dimensional model can be evenly divided along the radius into any number of two-dimensional linear models. In this example, the three-dimensional model is reduced to five layers, or five linear models, each corresponding to a corresponding radial position (relative to the central axis).

[0107] refer to Figure 14 As a non-limiting example, to parameterize the flux barriers in a rotor core having 10 flux barriers, 20 semi-elliptical curves on the innermost radial circumferential surface and the outermost radial circumferential surface can be expressed as:

[0108] Table 4 lists the preferred set of geometric parameter values ​​of the rotor magnetic barriers obtained.

[0109] Once the linear model satisfies the above constraints, a series of simulations can be performed. The torque of the linear model can be obtained by the calculation formula (5) provided above.

[0110] Comparing 2D and 3D simulations also confirms that 2D models are an effective alternative to 3D models. Using 2D models instead of 3D models significantly reduced the computation time for 1,482 test cases to approximately 47 hours, 7 minutes, and 35 seconds. The average computation time per case was 114.5 seconds, compared to approximately 50 minutes for a single 3D simulation case, representing a 96% computational time savings.

[0111] The winding dimensions can be further optimized for three-dimensional structural parameters. To fully utilize radial space and allocate more copper to the slots, the stator yoke dimensions can be adjusted by reducing the radial width of the yoke cross section and increasing its axial height, while maintaining the same cross-sectional area. This provides more space for the annular windings. Consequently, more copper can be used to increase the torque of the proposed motor. Based on the optimization results, a smaller stator yoke width results in greater torque and a higher torque density, due to the use of more copper and the input current.

[0112] For purposes of illustration and not limitation, Table 5 below shows an exemplary set of geometric parameters obtained for this example.

[0113] The performance of the motor was simulated and tested experimentally. Table 6 above shows the theoretically calculated electromagnetic performance.

[0114] Figure 15 The BH curves of the additively manufactured rotor in the "as built" state (before annealing) and after annealing are shown. Testing verified that the magnetic properties of the prototype rotor core meet multiple standards, including international standards (such as IEC 60404-2, IEC 60404-3, and IEC 60404-6) and national standards (such as GB / T 3655-2008, GB / T 13789-2008, GB / T 3658-2008, and GB / T 19346.1-2017). The rotor core's saturation magnetic flux density can reach approximately 1.5 Tesla (T), a competitive magnetic performance close to that of commercial silicon steel sheet products.

[0115] The rated torque was tested for this example of the proposed motor, and Figure 16 The waveform of the rated torque is shown. As shown in the figure, the average rated torque is 3.58 Nm, and the peak-to-peak ripple is only 7.8%. In this case, the proposed machine can provide a torque density of 4.43 Nm / L or 0.965 Nm / kg.

[0116] Figure 17 The experimental performance test results of the prototype device of the proposed motor are shown. In this example, the torque density reaches its peak value when the width is about 15.5 mm and the optimal size of the yoke cross section is 15.5 mm wide × 16.4 mm high. In this example, at 5 The prototype's on-load performance was tested at 100 rpm and 200 rpm. The test results showed an average torque of 1.98 Nm, which is approximately 7% lower than the simulated value, but still demonstrates the feasibility and potential of the proposed SynRM100. The deviation may be due to tolerances or machining errors in the prototype's manufacturing.

[0117] The compact structure of the segmented stator and contact metal surfaces in the proposed SynRM100 achieves relatively high space utilization and good thermal conductivity. Overall, the proposed motor is characterized by high thermal load tolerance and small size, which is beneficial for achieving higher torque density than conventional synchronous reluctance motors.

[0118] The geometric parameter values ​​of the flux barriers provided above are only used to assist understanding and are not limiting. Different shapes and profiles can be used for the flux barriers 870 to set the magnetic flux path 150 in different examples of the rotor core 800, such as Figures 18 to 21 The rotor core 800 is preferably manufactured by 3D printing or additive manufacturing technology, thereby achieving greater flexibility in implementing different three-dimensional magnetic flux distributions.

[0119] To assist in understanding further details of the magnetic barrier in the rotor core, a method for obtaining a printing model for 3D printing is described. The method for providing the magnetic barrier may include establishing a simulation model of the rotor core, such as Figure 22 Model-S (920) and Model-L (900) are shown. The model can be easily parameterized and facilitates simulation. The method can also include developing a printed model, such as Figure 22 Model-P (930) is shown as part of a printing strategy for a 3D-printed rotor core. Testing has shown that the 3D-printed rotor core manufactured in this manner can substantially mirror the performance of the simulation model while accounting for the limitations of current 3D printing technology. The above method can provide a comprehensive approach for developing the proposed 3D-printed rotor core.

[0120] Different 3D printers can be used. In one example, a prototype device of the proposed rotor core was printed using a TruPrint 1000 (available from Trumpf) equipped with two 200W fiber lasers and using Selective Laser Melting (SLM) technology.

[0121] Metal powder is melted layer by layer by the laser to build up the workpiece, e.g. Figure 23 To reduce the need for additional support structures during printing, the rotor core can be printed radially along the central axis of the magnetic barrier, from the outermost radius to the innermost radius (see Figure 22 The rotor can thus be printed in one go.

[0122] In some examples, the rotor core can be printed as multiple independent rotor core pieces. The printing process can involve printing Z p The initial layer of the printed rotor core can be attached to the flat top surface of the base, such as Figure 23This forms a trapezoidal printed rotor core with a circular top surface, as shown in the middle left figure of Figure 23 The difference between Model-P and Model-S is Figure 22 Additional parts shown. Z p The combination of the printing cores constitutes the final combined rotor, which has Z p A polygonal shape with three edges.

[0123] Still refer to Figure 23 , the magnetic barrier contours in Model-L and Model-S are located on the circumferential surface Since the model P is printed layer by layer, each printing plane The magnetic barriers on the model are not completely aligned with the magnetic barriers in Model-L and Model-S. To be more precise, the magnetic barriers can be aligned by connecting the circumferential surface R with the corresponding printed plane. A series of intersection points between them form a printing plane The specific curve 932 on the The continuous change of the circumferential surface The curve should follow the following expression derived from (9) to (11):

[0124] This application proposes a rotor that breaks with conventional thinking about rotor core manufacturing to provide a three-dimensional flux path. This is in contrast to many types of conventional motors, in which the flux path is two-dimensional, for example, the flux path is essentially set within a flat plane. In addition, the proposed three-dimensional flux path is defined by irregularly shaped magnetic barriers. This axial flux motor has a larger radial diameter, which provides higher torque compared to conventional radial flux settings. The silicon iron rotor core (Si-Fe rotor core) can be customized in terms of magnetic orientation, BH characteristics, resistance, mechanical strength, etc., depending on the required electromagnetic properties, 3D printing materials, dimensions and parameters. Therefore, the proposed 3D-Printed Rotor Axial-Flux Synchronous Reluctance Motor (3DPR-AF-SynRM) has the potential to achieve high performance.

[0125] In an axial flux motor, the orthogonal positional relationship between the magnetic barrier axis and the direction of rotation beneficially protects the rotor core from the significant mechanical stresses found in conventional motors. Conventional motors inevitably experience significant mechanical stresses that can cause the rotor core to fracture. The proposed SynRM eliminates the need for a magnetic bridge to strengthen the mechanical structure. In this case, the proposed SynRM is characterized by a relatively high salient pole ratio (also known as saliency ratio).

[0126] To verify the mechanical strength of the proposed rotor core, the mechanical properties of the 3D printed rotor core samples were tested. Figure 24 The test results shown graphically demonstrate that the mechanical strength of the proposed rotor core is superior to that of the conventional rotor.

[0127] Mechanical stress analysis was also performed. The results showed that even at a rotational speed of 20,000 RPM, the rotor core exhibited only 22 microns of deformation. This excellent performance further demonstrates the suitability of the proposed motor for high-speed applications. In this case, motor efficiency can reach as high as 94%. Notably, these impressive performance figures are based on preliminary prototype equipment, demonstrating that superior performance can be achieved in practical implementations of the proposed SynRM100.

[0128] In embodiments employing a double-sided rotor configuration, the looped windings double the torque without requiring additional current. This SynRM eliminates the need for conventional overlapping windings with larger winding ends. In contrast, the SynRM uses stator segments with individually mounted windings, which have relatively small winding ends. As a result, significantly more compact motors with greater internal space utilization and higher torque density are possible.

[0129] The proposed SynRM exhibits relatively high torque / power density suitable for gearless direct-drive applications, expanding the range of applications for the proposed SynRM. Industrial or commercial applications require high torque / power density and direct drive, even in harsh operating conditions (high temperature, severe vibration, and humid environments). Potential applications include, but are not limited to, spacecraft, hybrid electric vehicles, marine propulsion, and electric aircraft.

[0130] The present application describes different embodiments of a synchronous reluctance motor. The synchronous reluctance motor includes: a stator and a first rotor. The stator has a first stator side and a second stator side opposite the first stator side. The stator includes: a plurality of stator teeth arranged radially symmetrically about a central axis; and a plurality of windings arranged radially symmetrically about the central axis. The plurality of windings are oriented to set a ring-shaped wire group about the central axis. Each winding is respectively arranged between two adjacent stator teeth. A first rotor is arranged on the first stator side. The first rotor can rotate relative to the stator about the central axis. The first rotor includes: a plurality of first rotor cores arranged radially symmetrically about the central axis. Each first rotor core includes: a first proximal surface facing the winding; and a plurality of first magnetic flux paths. The plurality of first magnetic flux paths can be defined by a plurality of first magnetic barriers interlaced with the plurality of first magnetic flux paths, wherein each of the plurality of first magnetic flux paths has two ends adjacent to the first proximal surface.

[0131] The axial magnetic flux may be formed in response to the current in the selected winding.The axial magnetic flux may include a plurality of axially extending segments parallel to the central axis and a plurality of curved segments corresponding to the plurality of first flux barriers.

[0132] The synchronous reluctance motor may further include a first rotor housing. The first rotor housing may define a first housing cavity to accommodate a corresponding first rotor core among the plurality of first rotor cores.

[0133] The first rotor core may further include: an outer surface; and an inner surface. The inner surface faces away from the outer surface. The inner surface is arranged to have a radial distance from the central axis shorter than a radial distance from the outer surface to the central axis.

[0134] The inner surface may be configured as a concave surface.

[0135] The outer surface may be configured as a planar surface.

[0136] The flux barrier may extend across the radial length of the rotor core.

[0137] The first magnetic flux path may be characterized by a reluctance lower than a reluctance of the first plurality of magnetic barriers.

[0138] Each of the plurality of first flux barriers may include an air gap.

[0139] Each first magnetic flux path may define a continuous path originating from and terminating at the first proximal surface.

[0140] Each first flux barrier may define an arcuate cross-sectional shape.

[0141] Each first magnetic barrier may define a partially elliptical cross-sectional shape.

[0142] Each first magnetic barrier may define an irregular cross-sectional shape.

[0143] The stator may further include a plurality of stator yokes, wherein each winding may be disposed around a corresponding stator yoke of the plurality of stator yokes.

[0144] Each stator yoke may be disposed between respective major surfaces of adjacent stator teeth.

[0145] Each winding may be coupled to a corresponding stator tooth and a corresponding stator yoke to form a stator segment.

[0146] The synchronous reluctance motor may further include a stationary ring coupled to the plurality of stator segments.

[0147] The rotor core can be additively manufactured.

[0148] The synchronous reluctance motor may further include a second rotor. The second rotor may be disposed on the second stator side, wherein the second rotor is rotatable relative to the stator about a central axis. The second rotor includes a plurality of second rotor cores disposed radially symmetrically about the central axis. Each second rotor core may include a second proximal end surface facing the winding; and a plurality of second magnetic flux paths. The plurality of second magnetic flux paths may be defined by a plurality of second magnetic barriers interlaced with the plurality of second magnetic flux paths, wherein each of the plurality of second magnetic flux paths has two ends adjacent to the second proximal end surface.

[0149] The first proximal surface and the second proximal surface may be disposed in opposite directions facing each other.

[0150] During operation of the synchronous reluctance motor, an axial magnetic flux is generated. The axial magnetic flux may include: a plurality of first curved magnetic flux paths corresponding to the plurality of first magnetic flux paths of the first rotor core; a plurality of second curved magnetic flux paths corresponding to the plurality of second magnetic flux paths of the second rotor core; and a plurality of axially oriented magnetic flux paths extending between the first curved segments and the second curved segments, wherein the plurality of axially oriented magnetic flux paths are parallel to the central axis.

[0151] All examples described herein, whether devices, methods, materials or products, are presented for illustrative purposes and to aid understanding, and are not intended to be limiting or exhaustive. Those skilled in the art may make modifications without departing from the scope of the claims of this application.

Claims

1. A synchronous reluctance motor, comprising: a stator having a first stator side and a second stator side opposite the first stator side, the stator comprising: a plurality of stator teeth arranged radially symmetrically about a central axis; and a plurality of windings arranged radially symmetrically about the central axis, the plurality of windings being oriented to define a looped wire group about the central axis, each of the plurality of windings being respectively arranged between two adjacent stator teeth; and a first rotor, which is disposed on the first stator side and is rotatable relative to the stator about the central axis, and includes: A plurality of first rotor cores are arranged radially symmetrically about the central axis, each of the plurality of first rotor cores respectively having: a first proximal surface facing toward the plurality of windings; and A plurality of first magnetic flux paths are defined by a plurality of first magnetic barriers interleaved with the plurality of first magnetic flux paths, wherein each of the plurality of first magnetic flux paths has two ends adjacent to the first proximal surface.

2. The synchronous reluctance motor of claim 1 , wherein an axial magnetic flux is formed in response to current in a selected winding, the axial magnetic flux comprising a plurality of axially extending segments parallel to the central axis and a plurality of curved segments corresponding to the plurality of first flux barriers. 3 . The synchronous reluctance motor according to claim 1 , further comprising a first rotor housing defining a first housing cavity to accommodate a corresponding first rotor core among the plurality of first rotor cores.

4. The synchronous reluctance motor according to any one of claims 1 to 3, wherein the first rotor core further comprises: External surface; as well as An inner surface is disposed opposite to the outer surface, wherein the inner surface is disposed at a radial distance from the central axis shorter than a radial distance from the outer surface to the central axis. The synchronous reluctance motor according to claim 4 , wherein the inner surface is configured as a concave surface.

6. The synchronous reluctance motor according to claim 4 or 5, wherein the outer surface is configured as a planar surface.

7. A synchronous reluctance machine according to any one of claims 4 to 6, wherein the flux barrier extends across a radially oriented length of the rotor core.

8. The synchronous reluctance machine of any one of claims 1 to 7, wherein the plurality of first flux paths are characterized by a reluctance lower than a reluctance of the plurality of first flux barriers. 9 . The synchronous reluctance motor of claim 8 , wherein each of the plurality of first flux barriers comprises an air gap.

10. The synchronous reluctance motor of claim 8 or 9, wherein each first flux path of the plurality of first flux paths defines a continuous path originating from and terminating at the first proximal end surface.

11. The synchronous reluctance motor of any one of claims 1 to 10, wherein each of the plurality of first flux barriers defines an arcuate cross-sectional shape.

12. The synchronous reluctance motor of any one of claims 1 to 10, wherein each of the plurality of first flux barriers defines a partially elliptical cross-sectional shape.

13. The synchronous reluctance motor of any one of claims 1 to 10, wherein each first flux barrier of the plurality of first flux barriers defines an irregular cross-sectional shape.

14. The synchronous reluctance motor according to any one of claims 1 to 13, wherein the stator further comprises a plurality of stator yokes, and wherein each of the plurality of windings is disposed around a corresponding stator yoke of the plurality of stator yokes. 15 . The synchronous reluctance motor of claim 14 , wherein each of the plurality of stator yokes is disposed between respective major surfaces of adjacent ones of the plurality of stator teeth. 16 . The synchronous reluctance motor according to claim 14 , wherein each winding of the plurality of windings is coupled to a corresponding stator tooth of the plurality of stator teeth and a corresponding stator yoke to constitute a stator segment. 17 . The synchronous reluctance motor of claim 16 , further comprising a stationary ring coupled to the plurality of stator segments.

18. A synchronous reluctance machine according to any one of claims 1 to 17, wherein the rotor core is additively manufactured.

19. The synchronous reluctance motor according to any one of claims 1 to 18, further comprising: a second rotor, the second rotor being disposed on the second stator side and being rotatable relative to the stator about the central axis, the second rotor comprising: A plurality of second rotor cores are arranged radially symmetrically about the central axis, each of the plurality of second rotor cores respectively having: a second proximal surface facing toward the plurality of windings; and A plurality of second magnetic flux paths are defined by a plurality of second magnetic barriers interleaved with the plurality of second magnetic flux paths, wherein each second magnetic flux path in the plurality of second magnetic flux paths has two ends adjacent to the second proximal end surface. 20 . The synchronous reluctance motor of claim 19 , wherein the first proximal end surface and the second proximal end surface are disposed in opposite directions facing each other.

21. The synchronous reluctance motor according to claim 20, wherein an axial magnetic flux is generated during operation, and the axial magnetic flux comprises: a plurality of first curved magnetic flux paths corresponding to the plurality of first magnetic flux paths of the first rotor core; a plurality of second curved magnetic flux paths corresponding to the plurality of second magnetic flux paths of the second rotor core; as well as A plurality of axially oriented magnetic flux paths extend between the plurality of first curved segments and the plurality of second curved segments, the plurality of axially oriented magnetic flux paths being parallel to the central axis.

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