WO2017044090A1

WO2017044090A1 - System and method for supporting laminations of synchronous reluctance motors

Info

Publication number: WO2017044090A1
Application number: PCT/US2015/049148
Authority: WO
Inventors: Kevin Michael Grace
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2015-09-09
Filing date: 2015-09-09
Publication date: 2017-03-16
Anticipated expiration: 2018-03-09

Abstract

A synchronous reluctance machine includes a rotor having a plurality of rotor poles disposed about an axis. A first rotor pole of the plurality of rotor poles includes a body portion having an interior surface, a first discrete portion, a first wedge, and a first lacing. The interior surface of the body portion is nearer to the axis than the first discrete portion. The first wedge is radially disposed between the body portion and the first discrete portion. The first lacing is configured to radially bind the first discrete portion and the first wedge to the body portion. The first wedge and the first lacing are configured to electrically and magnetically isolate the body portion from the first discrete portion.

Description

SYSTEM AND METHOD FOR SUPPORTING LAMINATIONS

OF SYNCHRONOUS RELUCTANCE MOTORS

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH &

DEVELOPMENT

[0001] This invention was made with Government support under contract number DE-EE0005573 awarded by the Department of Energy. The Government has certain rights in the invention.

BACKGROUND

[0002] The subject matter disclosed herein relates to electric motors, and more specifically, to supporting laminations of synchronous reluctance motors

[0003] Electric motors typically have a stationary stator with poles that generate a rotating magnetic field to drive poles of a rotor. The rotor rotates relative to the stator, thereby rotating a shaft coupled to the rotor. The stator may generate the rotating magnetic field from a supplied current, such as an alternating current. The rotor of a reluctance motor does not receive an electric current. Rather, the magnetic flux of the stator is conducted through the poles of the rotor, generating torque via magnetic reluctance. A synchronous reluctance motor is an alternating current motor for which the rotation of the shaft is synchronized with the frequency of the alternating current. Channels of the rotor poles carry magnetic flux to generate the torque. Connections and conductive radial posts between channels of each rotor pole increases leakage flux between the channels. Additionally, sleeves or other materials disposed between the rotor and the stator may increase an airgap between the rotor and the stator.

BRIEF DESCRIPTION

[0004] Certain embodiments commensurate in scope with the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the claimed subject matter, but rather these embodiments are intended only to provide a brief summary of possible forms of the disclosed subject matter. Indeed, the disclosed subject matter may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

[0005] In one embodiment, a synchronous reluctance machine includes a rotor having a plurality of rotor poles disposed about an axis. A first rotor pole of the plurality of rotor poles includes a body portion having an inner surface, a first discrete portion, a first wedge, and a first lacing. The inner surface of the body portion is nearer to the axis than the first discrete portion. The first wedge is radially disposed between the body portion and the first discrete portion. The first lacing is configured to radially bind the first discrete portion and the first wedge to the body portion. The first wedge and the first lacing are configured to electrically and magnetically isolate the body portion from the first discrete portion.

[0006] In another embodiment, a synchronous reluctance machine includes a rotor having a plurality of rotor poles disposed about an axis. A first rotor pole of the plurality of rotor poles includes a body portion having an inner surface, an inner discrete portion, an inner wedge, an outer discrete portion, an outer wedge, and a first lacing. The inner surface of the body portion is nearer to the axis than the inner discrete portion. The inner wedge is radially disposed between the body portion and the inner discrete portion, and the inner wedge is configured to electrically and magnetically isolate the body portion from the inner discrete portion. The outer discrete portion is radially disposed outside the inner wedge and the inner discrete portion relative to the axis. The outer wedge is radially disposed between the inner discrete portion and the outer discrete portion. The outer wedge is configured to electrically and magnetically isolate the outer discrete portion from the inner discrete portion. The first lacing is configured to radially bind the inner discrete portion, the outer discrete portion, the inner wedge, and the outer wedge to the body portion. The first lacing is also configured to electrically and magnetically isolate the body portion from the inner discrete portion and the outer discrete portion.

[0007] In another embodiment, a method of manufacturing a synchronous reluctance machine includes layering a first wedge and a first discrete portion radially outside a body portion of a rotor pole of a rotor, and binding with a first lacing the first discrete portion and the first wedge to the body portion. The first wedge is configured to electrically and magnetically isolate the body portion from the first discrete portion. The first lacing is configured to enclose the first discrete portion and the first wedge in a radial direction and an axial direction relative to an axis of the rotor, an exterior surface of the rotor is disposed at an outer radius from the axis. The first lacing is radially disposed between the outer radius of the rotor and the axis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0009] FIG. 1 is a schematic diagram illustrating an embodiment of a synchronous reluctance machine, in accordance with aspects of the present disclosure;

[0010] FIG. 2 is a perspective view of an embodiment of a rotor and lacings of the synchronous reluctance machine of FIG. 1, in accordance with aspects of the present disclosure;

[0011] FIG. 3 is an axial cross-sectional view of an embodiment of a section of the rotor of the synchronous reluctance machine and lacings of FIG. 2, in accordance with aspects of the present disclosure;

[0012] FIG. 4 is an axial cross-sectional view of an embodiment of a section of the rotor of the synchronous reluctance machine and lacings of FIG. 2, in accordance with aspects of the present disclosure; and

[0013] FIG. 5 is a flowchart of an embodiment of a method of assembling the synchronous reluctance machine of FIG. 1, in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0014] One or more specific embodiments of the presently disclosed subject matter will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0015] When introducing elements of various embodiments of the presently disclosed subject matter, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0016] Synchronous reluctance machines (e.g., motors) have a plurality of rotor poles that rotate relative to stator poles, thereby generating torque on a shaft coupled to the synchronous reluctance machine. That is, synchronous reluctance machines (e.g., motors) generate torque on a shaft by rotating a rotor and rotor poles coupled to the shaft relative to stator poles of a stator. Stator poles of a reluctance motor may create magnetic flux in ferromagnetic (e.g., steel) rotor poles, and the changing magnetic field of the stator poles drives the rotation of the rotor poles. Each rotor pole may be formed from discrete stacks of laminations. Each discrete stack of laminations of a rotor pole may be radially offset by one or more non-conductive wedges. One or more lacings extending in an axial direction along the rotor radially retain the discrete stacks and non-conductive wedges of the rotor pole during operation (e.g., rotation) of the synchronous reluctance machine. The lacings radially may bind the discrete stacks of laminations and non-conductive wedges of each rotor pole to a rotor body. As described in detail below, the lacings that bind the discrete stacks of laminations of each rotor pole to the rotor body reduce or eliminate leakage flux between discrete stacks of laminations of a rotor pole. The radial offset between each discrete stack of laminations reduces or eliminates leakage flux conducted between each discrete stack of a rotor pole. Reducing leakage flux between the stacks of laminations of a rotor pole may increase the power density and/or may improve the power factor of the synchronous reluctance machine. For example, the lacings may enable a rotor with a given radius (e.g., approximately 100 mm) configured to operate at a first speed (e.g., 10,000 rpm) to operate at a higher second speed (e.g., 14,000 rpm), thereby increasing the power output of the synchronous reluctance machine. Additionally, or in the alternative, the lacings may enable a rotor with a first radius configured to operate at a given speed (e.g., 10,000 rpm) to operate with a greater second radius, thereby increasing the power output of the synchronous reluctance machine. The lacings provide radial support to the laminations, thereby reducing stresses on the laminations during operation, without increasing an air gap between the rotor and the stator.

[0017] Turning to the drawings, FIG. 1 is a schematic diagram that illustrates an embodiment of a rotational system 10 (e.g., rotary machinery such as turbomachinery) with a synchronous reluctance machine 12 (e.g., synchronous reluctance motor) coupled to one or more loads 14. The synchronous reluctance machine 12 may include, but is not limited to a wind-driven motor or a hydro-driven motor. In the rotational system 10, the synchronous reluctance machine 12 provides a rotational output 16 to the one or more loads 14 via a shaft 18. The synchronous reluctance machine 12 receives power (e.g., electric power) from a power source 20 that may include, but is not limited to, an electric generator, a mains power source (e.g., three- phase, single-phase), a battery, or any combination thereof. The one or more loads 14 may include, but is not limited to, a vehicle or a stationary load. In some embodiments, the one or more loads 14 may include a propeller on an aircraft, one or more wheels of a vehicle, a compressor, a pump, a fan, any suitable device capable of being powered by the rotational output of the synchronous reluctance machine 12, or any combination thereof. The shaft 18 rotates along an axis 22. [0018] The synchronous reluctance machine 12 includes a stator 24 and a rotor 26. The rotor 26 may be disposed within the stator 24, offset by an airgap 28 between an interior surface 30 of the stator 24 and an exterior surface 32 of the rotor 26. As may be appreciated, in some embodiments, the interior surface 30 of the stator 24 is cylindrical. Stator poles 34 receiving power from the power source 20 are configured to generate magnetic fields to drive the rotor 26 and shaft 18 about the axis 22. The stator poles 34 may be powered so that the generated magnetic fields rotate about the axis 22. In some embodiments, the stator poles 34 are axially spaced along the stator 24, opposite the rotor 26. The stator poles 34 are circumferentially spaced about the stator 24. While FIG. 1 illustrates a longitudinal view of the synchronous reluctance machine 12 with only two sets of stator poles 34 (i.e., a first set of stator poles 34 along a top section 37, and a second set of stator poles 34 along bottom section 39 of the stator 24), it may be appreciated that the stator 24 may have more than two sets of stator poles 34 circumferentially spaced about the axis 22. For example, the stator 24 may have 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 24, 36, or more sets of stator poles 34 circumferentially spaced about the axis 22.

[0019] The magnetic flux of the stator poles 34 is conducted through rotor poles of the rotor 26, thereby driving the rotor 26 and the shaft 18 about the axis 22. The rotor 26 may have a plurality of laminations 36 stacked in an axial direction 44. The laminations 36 reduce eddy currents from the induced magnetic field from the stator poles 34, thereby reducing inductive heating and energy loss of the rotor 26. In some embodiments, the rotor 26 has approximately 10, 20, 50, 100, 500, 1000, or more laminations 36 axially stacked between the end plates 42. As discussed in detail below, each lamination 36 may have a body and one or more discrete portions that conduct the magnetic flux from the respective stator pole 34. For example, each rotor pole of the rotor 26 may include the body and one or more discrete portions of the lamination 36. Accordingly, the rotor poles of the rotor 26 may be formed from stacks of discrete portions of multiple laminations 36. For clarity, FIG. 1 illustrates the body of a lamination 36 together with the one or more discrete portions, and FIGS. 2-4 separately identify the one or more discrete portions and the body of each lamination 36. [0020] Lacings 46 extend along the rotor 26 and form loops. The loops facilitate retention of the discrete portions in a radial direction 48 during operation of the synchronous reluctance machine. The loops generally extend in the axial direction 44 along the rotor 26. In some embodiments, the lacings 46 extend in the axial direction 44 through the laminations 36. Additionally, or in the alternative, the lacings 46 may extend in the axial direction 44 through the rotor 26. The lacings 46 form a loop (e.g., continuous loop) that extend in the axial direction 44 and the radial direction 48 along the rotor 26. In some embodiments, each rotor pole of the rotor 26 corresponds to one or more lacings 46. The one or more lacings 46 of the rotor 26 radially retain the discrete portions relative to a body 50 (e.g., center region) of a rotor pole during operation of the synchronous reluctance machine 12.

[0021] In some embodiments, the stator poles 34 extend axially a distance 38 opposite the rotor 26, where the distance 38 is opposite laminations 36 of the rotor 26 or opposite a length 40 of the rotor 26. The length 40 of the rotor 26 may include portions of end plates 42 coupled to the shaft 18. In some embodiments, the length 40 of the rotor 26 is approximately 10 to 500 mm, 50 to 150 mm, 60 to 100 mm, or approximately 70 to 80 mm. In some embodiments, the laminations 36 are axially disposed between end plates 42. The lacings 46 may extend through and/or bind the laminations 36 to the end plates 42.

[0022] The lacings 46 may be formed of a material (e.g., carbon composite) that does not conduct electrical current or the magnetic field well relative to the laminations 36. As described below, the lacings 46 may radially retain the discrete stacks of the rotor poles without conducting appreciable electrical current or magnetic flux between the discrete stacks (e.g., channels) of each rotor pole. Accordingly, embodiments of the rotor 26 described herein are believed to reduce or eliminate leakage flux relative to a rotor with conductive connections or conductive supports between channels of the rotor poles.

[0023] The laminations 36 may extend a radial distance 47 from the shaft 18, thereby forming the exterior surface 51 of the rotor 26 offset from the interior surface 30 of the stator 24 by the airgap 28. In some embodiments, the lacings 46 are entirely disposed within the radial distance 47 such that no portion of the lacings 46 reduces the airgap 28 between the rotor 26 and the stator 24. In some embodiments, the end plates 42 and the laminations 36 may extend approximately the same radial distance 47 from the shaft 18, thereby forming the exterior surface 32 of the rotor 26. The term "approximately" as utilized herein with respect to the radial distance 47 may include distances within 10 percent. That is, the laminations 36 may extend radially beyond the end plates 42 by up to 10 percent in some embodiments. In some embodiments, an outer diameter 49 of the rotor 26 is between approximately 50 to 500 mm, 150 to 300 mm, 175 to 250 mm, or 200 to 225 mm. However, the lacings 46 may be entirely disposed within the outer diameter 49 of the rotor 26 such that the lacings 46 do not reduce the airgap 28 between the exterior surface 32 and the interior surface 30.

[0024] The material of the laminations 36 may include, but is not limited to laminated silicon steel, a carbonyl iron, or a ferrite ceramic, or any combination thereof. In some embodiments, each lamination 36 may be cut (e.g., mechanically cut, electrically cut, laser cut) or stamped from a sheet, such as a laminated silicon steel sheet. The body and discrete portions of each lamination 36 form rotor poles that carry the magnetic flux. The rotor poles are circumferentially spaced about the axis 22. The quantity of rotor poles of the rotor 26 may be the same or less than the quantity of stator poles 34 of the stator 24. As may be appreciated, a synchronous reluctance machine 12 has an equal number of stator poles and rotor poles. In some embodiments, each lamination 36 has multiple (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 24, 36, or more) rotor poles. In some embodiments, each rotor pole is formed of separate stacks of laminations 36.

[0025] The lacings 46 are configured to provide radial support for the laminations 36 during operation of the synchronous reluctance machine 12. As the rotor 26 rotates about the axis 22, a centrifugal force in the radial direction 48 out from the axis 22 generates stress on components (e.g., laminations 36, lacings 46) of the rotor 26. The lacings 46 are configured to interface with the discrete portions of the laminations 36 to enable the lacings 46 to carry the radial stress generated by the centrifugal force, thereby reducing deformation of the laminations 36 and maintaining the airgap 28 between the exterior surface 32 of the rotor 26 and the inner surface 30 of the stator 24. In some embodiments, each rotor pole has one or more lacings 46. The lacings 46 may be wound around the rotor poles such that the lacings 46 do not extend radially beyond any portion of the rotor 26.

[0026] As may be appreciated, the materials of the lacings 46 may be nonmagnetic, thereby reducing the effect of the lacings 46 on the magnetic field through the body and discrete portions of the laminations 36. In some embodiments, the lacings 46 are formed of a carbon composite material, such as IM7 carbon composite. Carbon composite material may have a tensile strength greater than steel, such as approximately 4,136 MPa (600 ksi). In some embodiments, the materials (e.g., composite materials) of the lacings 46 may have a tensile strength that is approximately twelve times or more greater than the tensile strength of the laminations 36. In some embodiments, each lacing 46 is formed from one or more carbon composite threads wound around the respective rotor pole. Additionally, or in the alternative, each lacing 46 is formed from one or more carbon composite sheets wound around the respective rotor pole. It may be appreciated that in some embodiments, the rotor 26 may have multiple sections 52, each with a plurality of laminations 36 that form rotor poles opposite stator poles 34 of the stator 24. Each section 52 of the rotor 26 may be approximately the same length (e.g., distance 38), and each section 52 may have approximately the same quantity of laminations 36. Moreover, each section 52 may have separate sets of lacings 46.

[0027] FIG. 2 is a perspective view of an embodiment of the rotor 26 of FIG. 1 that shows the lacings 46 wound around laminations 36 of the rotor 26. The rotor 26 of FIG. 2 has 10 rotor poles 54, although other embodiments of the rotor 26 may have a different quantity (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 24, 36, or more) of rotor poles 54. Each rotor pole 54 has a body portion 56 and one or more discrete portions 58. For example, each of the rotor poles 54 of the embodiment of the rotor 26 shown in FIG. 2 have two C-shaped discrete portions 58. The discrete portions 58 may be electrically separated from one another and from the body portion 56 of the respective rotor pole 54 by one or more wedges 60. Materials for the one or more wedges 60 may include, but are not limited to non-conductive materials such as fiberglass, plastic, composite materials, or any combination thereof. In some embodiments, gaps 62 may be disposed between the one or more wedges 60 and the discrete portions 58. In some embodiments, the gaps 62 may receive a cooling fluid (e.g., air) configured to cool the rotor 26. Some of the wedges 60 and/or the gaps may extend in the axial direction 44 the length 40 of the rotor 26. The one or more wedges 60 and the gaps 62 of each rotor pole 54 enable the discrete portions 58 to be electrically isolated from one another and from the body portion 56 of the rotor pole 54. Accordingly, the wedges 60 and any gaps 62 reduce or eliminate magnetic flux leakage between the discrete portions 58. Thus, the active parts (e.g., body portion 56, discrete portions 58) of the rotor 26 that provide functionality to the synchronous reluctance machine 12 are magnetically decoupled from the parts (e.g., wedges 60, gaps 62, lacings 46) of the rotor 26 that provide structural support of the rotor 26. Moreover, the structural parts (e.g., wedges 60, gaps 62, lacings 46) of the rotor 26 do not reduce the air gap of the synchronous reluctance machine 12, thereby improving the electromagnetic performance of the synchronous reluctance machine 12.

[0028] The materials of the lacings 46 may increase the radial stress operational range of the rotor 26. That is, the lacings 46 may reduce or eliminate the effects of the mechanical strength of the laminations 36 on the radial stress operational range of the rotor 26. As may be appreciated, radial stresses within the rotor 26 are directly related to the radius and the rotational speed of the rotor 26. Accordingly, an embodiment of the synchronous reluctance machine 12 with a first rotor radius (e.g., approximately 100 mm) and the lacings 46 as discussed herein may enable the synchronous reluctance machine to operate at a first rotational speed (e.g., 14,000 rpm) that is greater than a second rotational speed (e.g., 10,000 rpm) of another synchronous reluctance machine with the same first rotor radius without the lacings 46. Thus, the lacings 46 may facilitate increasing the power output of the synchronous reluctance machine 12 without necessarily increasing the rotor radius. Additionally, or in the alternative, the tensile strength of the lacings 46 may enable an embodiment of the synchronous reluctance machine 12 configured to operate at the second rotational speed (e.g., 10,000 rpm) to operate with a greater second radius (e.g., approximately 150 mm), thereby increasing the power output of the synchronous reluctance machine 12 without necessarily increasing the rotational speed. Therefore, the lacings 46 may enable embodiments of the synchronous reluctance machine 12 to become smaller and more power dense than some synchronous reluctance machines without the lacings 46.

[0029] FIG. 3 is an axial cross-sectional view of an embodiment of a section of the rotor 26 of the synchronous reluctance machine 12 and lacings 46 taken along line 3-3 of FIG. 2. As discussed above, the rotor poles 54 may have a body portion 56 and one or more discrete portions 58. In some embodiments, the body portion 56 for each of the rotor poles 54 is formed from a plurality of circumferential laminations 36 stacked in the axial direction 44. Each discrete portion 58 of the one or more discrete portions 58 of each rotor pole 54 may be shaped to conduct magnetic flux with the stator poles. For example, the discrete portions 58 may be U-shaped, C-shaped, D- shaped, semi-circular, and so forth. The discrete portions 58 may at least partially nest in the radial direction 48 with the body portion 56 of the respective rotor pole 54. In some embodiments, an outer discrete portion 64 may at least partially nest in the radial direction 48 within an inner discrete portion 66. While FIG. 3 illustrates each rotor pole 54 with two discrete portions 58, it may be appreciated that some embodiments of the rotor 26 may have 3, 4, 5, 6, 7, 8, or more discrete portions 58 per rotor pole 54.

[0030] As discussed above, the one or more wedges 60 and gaps 62 may separate each discrete portion 58 in the radial direction 48 from other discrete portions 58 and the body portion 56 of the rotor pole 54. A thickness 68 of the wedges 60 may be based at least in part on a leakage flux tolerance for the synchronous reluctance machine 12, the electrical conductivity of the wedges 60 and/or the gaps 62, or any combination thereof. Moreover, a thickness 70 of the discrete portions 58 may be based at least in part on the electrical conductivity of the discrete portions 58, the magnetic flux to be carried through the discrete portions 58, or any combination thereof. In some embodiments, the one or more wedges 60 may extend in the radial direction 48 toward the exterior surface 32 of the rotor 26. Extensions (e.g., legs) 72 of a wedge 60 may interface with the discrete portions 58 to radially retain the respective wedge 60 between the discrete portions 58 and/or between the inner discrete portion 66 and the body portion 56 during rotation of the rotor 26. The wedges 60 may extend axially along the length 40 of the rotor 26, thereby radially supporting multiple axially stacked laminations that form the discrete portions 58.

[0031] The lacings 46 may be configured to retain the discrete portions 58 in the radial direction 48 during rotation of the rotor 26. Each lacing 46 may be bound around a stack of multiple laminations 36 of the discrete portions 58 of a respective rotor pole 54. That is, each lacing 46 may axially and radially enclose the stacks of laminations 36 of the discrete portions 58 of a respective rotor pole 54, as illustrated in FIG. 2. Each rotor pole 54 of the rotor 26 may have one or more lacings 46 to radially support the discrete portions 58 during rotation of the rotor 26. Axial ends 74 of the lacings 46 may be oriented within approximately 45 degrees or less of the radial direction 48, as illustrated in FIGS. 2-4. In some embodiments, the axial ends 74 of the lacings are oriented to be parallel to the radial direction 48. Alignment of the axial ends 74 with the radial direction 48 may reduce shear stresses within the lacings 46 and may increase the tensile stresses within the lacings 46. As may be appreciated, the lacings 46 may have greater tensile strength than shear strength. Moreover, the lacings 46 axially and radially enclose the stacks of discrete portions 58 such that the radial forces on the discrete portions 58 during rotation of the rotor 26 generate tension stresses within the lacings 46.

[0032] In some embodiments, the lacings 46 may extend through ports 80 of the body portion 56 of the rotor pole 54, as illustrated in FIG. 3. An axial portion 76 of the lacings 46 is radially within an outermost extent (e.g., radius) of the exterior surface 32 of the rotor 26, as shown by the dotted line 82 spaced apart from the axial portion 76. Thus, each lacing 46 may be arranged so that the entire respective lacing 46 is radially within the exterior surface 32 and an interior surface 84 of the rotor 26. In some embodiments, the lacings 46 may axially and radially enclose the stacks of laminations 36 of the body portion 56 of a respective rotor pole 54, as illustrated in FIG. 4. The lacings 46 may interface with the outer discrete portion 64 and the interior surface 84 of the rotor 26. That is, an inner surface 88 (see FIG. 2) of the lacings 46 may interface with the outer discrete portion 64 and the rotor body portion 56. In some embodiments, the lacings 46 interface with notches 86 on the interior surface 84 of the rotor 26. The notches 86 may facilitate the desired placement of the lacings 46 to support the discrete portions 58.

[0033] FIG. 5 illustrates a method 100 of assembling the rotor 26 with the lacings 46 as described above. The laminations 36 forming the body portions 56 of the rotor poles are assembled (block 102) to form lamination stacks. In some embodiments, the lamination 36 with the body portion 56 for each rotor pole 54 is contiguous with the body portion 56 for one or more adjacent rotor poles 54. For example, each lamination 36 may have a generally circular shape that extends about the shaft 18. The laminations 36 may be assembled about the shaft 18. As discussed above, the rotor 26 may have approximately 10, 20, 50, 100, 500, 1000, or more axially stacked laminations 36. The one or more wedges 60 and the one or more discrete portions 58 may be layered (block 104) for each rotor pole 54. In some embodiments, the one or more wedges 60 may be positioned between radially adjacent discrete portions 58 and/or between a discrete portion 58 and the body portion 56 to form gaps 62. As illustrated in FIGS. 2-4 and described above, each rotor pole 54 may be layered such that extending radially outward from the shaft 18, each rotor pole 54 includes the rotor body portion 56, a first layer of one or more wedges 60 optionally with gaps 62, and a second layer with a discrete portion 58. In some embodiments, the second layer is an axial stack of laminations 36 that form the discrete portion 58 (e.g., inner discrete portion 66, outer discrete portion 64). The first and second layers may be layered in an alternating pattern in the radial direction 48 towards the exterior surface 32 of the rotor 26. As discussed above, some embodiments of the rotor 26 may have 3, 4, 5, 6, 7, 8, or more discrete portions 58 (e.g., second layers) per rotor pole 54.

[0034] The layered discrete portions 58 of each rotor pole 54 are bundled (block 106) with one or more lacings 46. The one or more lacings 46 for each rotor pole 54 radially bind the axially stacked discrete portions 58 to the axially stacked body portion 56 that forms the respective rotor pole 54. The one or more lacings 46 radially and axially enclose the axially stacked discrete portions 58 of the rotor pole 54. The one or more lacings 46 for each rotor pole 54 may be tightened or otherwise bundled about the discrete portions 58 to radially retain the discrete portions 58 and the one or more wedges 60 of the respective rotor pole 54 to the rotor body portion 56 during rotation of the rotor 26. As shown by node 108, the wedges 60 and discrete portions may be layered (block 104) and bundled (block 106) for each rotor pole 54 of the rotor until all the rotor poles 54 of the rotor 26 are layered and bundled as described above. In some embodiments, the end plates 42 are coupled (block 110) to the axial ends of the laminations 36 of the rotor 26 to assemble the rotor 26. The synchronous reluctance machine 12 may then be assembled (block 112) with the rotor 26 that has the lacings 46 for each rotor pole 54.

[0035] Technical effects of the presently disclosed subject matter include increased power density of a synchronous reluctance machine with reduced leakage flux between the discrete portions based at least in part on the electrical isolation of the discrete portions via the wedges. Additionally, the lacings enable a synchronous reluctance machine to radially retain discrete portions at increased rotor speeds and/or increased rotor radii while maintaining a desired airgap between the stator and the rotor. That is, the lacings may not radially extend beyond an outer radius of the rotor. Moreover, the increased strength provided by the lacings may enable synchronous reluctance machines sized for a certain load to be smaller, and therefore more power dense.

[0036] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

CLAIMS:

1. A synchronous reluctance machine, comprising:

a rotor comprising:

a plurality of rotor poles disposed about an axis, wherein a first rotor pole of the plurality of rotor poles comprises:

a body portion comprising an inner surface;

a first discrete portion, wherein the inner surface of the body portion is nearer to the axis than the first discrete portion;

a first wedge radially disposed between the body portion and the first discrete portion, wherein the first wedge is configured to electrically and magnetically isolate the body portion from the first discrete portion; and

a first lacing, wherein the first lacing is configured to radially bind the first discrete portion and the first wedge to the body portion, and the first lacing is configured to electrically and magnetically isolate the body portion from the first discrete portion.

2. The synchronous reluctance machine of claim 1, wherein the rotor comprises an exterior surface disposed at an outer radius from the axis, wherein the first lacing is radially disposed between the outer radius and the axis.

3. The synchronous reluctance machine of claim 1, wherein the first lacing forms a loop in an axial direction along the axis, and an inner surface of the first lacing interfaces with the first discrete portion and the body portion.

4. The synchronous reluctance machine of claim 1, wherein the first lacing interfaces with the inner surface of the body portion.

5. The synchronous reluctance machine of claim 1, wherein the first lacing comprises a carbon composite material.

6. The synchronous reluctance machine of claim 1, wherein the plurality of rotor poles comprises a plurality of laminations stacked in an axial direction of the rotor parallel to the axis, wherein the plurality of laminations comprises a body portion stack of laminations and a first discrete portion stack of laminations.

7. The synchronous reluctance machine of claim 1, wherein the first rotor pole of the plurality of rotor poles comprises a second wedge radially disposed between the body portion and the first discrete portion, the second wedge is configured to electrically and magnetically isolate the body portion from the first discrete portion, and the first wedge and the second wedge form a first gap between the body portion, the first discrete portion, the first wedge, and the second wedge.

8. The synchronous reluctance machine of claim 1, wherein the first rotor pole of the plurality of rotor poles comprises:

a second discrete portion radially disposed between the first wedge and the body portion; and

a second wedge radially disposed between the body portion and the second discrete portion, wherein the second wedge is configured to electrically and magnetically isolate the body portion from the second discrete portion, the first lacing is configured to radially bind the first discrete portion, the second discrete portion, the first wedge, and the second wedge to the body portion, and the first lacing is configured to electrically and magnetically isolate the body portion from both the first discrete portion and the second discrete portion.

9. The synchronous reluctance machine of claim 1, wherein the first rotor pole of the plurality of rotor poles comprises a second lacing, wherein the second lacing is configured to radially bind the first discrete portion and the first wedge to the body portion, and the second lacing is configured to electrically and magnetically isolate the body portion from the first discrete portion.

10. The synchronous reluctance machine of claim 1, wherein a second rotor pole of the plurality of rotor poles comprises:

the body portion;

a second discrete portion, wherein the inner surface of the body portion is nearer to the axis than the second discrete portion;

a second wedge radially disposed between the body portion and the second discrete portion, wherein the second wedge is configured to electrically and magnetically isolate the body portion from the second discrete portion; and

a second lacing, wherein the second lacing is configured to radially bind the second discrete portion and the second wedge to the body portion, the second lacing is configured to electrically and magnetically isolate the body portion from the second discrete portion, and the second rotor pole is circumferentially adjacent to the first rotor pole.

11. The synchronous reluctance machine of claim 1, wherein the first lacing comprises axial ends that are radially aligned with the axis.

12. A synchronous reluctance machine, comprising:

a rotor comprising:

a plurality of rotor poles disposed about an axis, where a first rotor pole of the plurality of rotor poles comprises:

a body portion comprising an inner surface;

an inner discrete portion, wherein the inner surface of the body portion is nearer to the axis than the inner discrete portion;

an inner wedge radially disposed between the body portion and the inner discrete portion, wherein the inner wedge is configured to electrically and magnetically isolate the body portion from the inner discrete portion;

an outer discrete portion disposed radially outside the inner wedge and the inner discrete portion relative to the axis;

an outer wedge radially disposed between the inner discrete portion and the outer discrete portion, wherein the outer wedge is configured to electrically and magnetically isolate the outer discrete portion from the inner discrete portion, and

a first lacing configured to radially bind the inner discrete portion, the outer discrete portion, the inner wedge, and the outer wedge to the body portion, and the first lacing is configured to electrically and magnetically isolate the body portion from the inner discrete portion and the outer discrete portion.

13. The synchronous reluctance machine of claim 12, wherein the rotor comprises an exterior surface disposed at an outer radius from the axis, wherein the first lacing is radially disposed between the outer radius and the axis.

14. The synchronous reluctance machine of claim 12, wherein the first lacing interfaces with the outer discrete portion and the inner surface of the body portion.

15. The synchronous reluctance machine of claim 12, wherein the outer discrete portion is configured to at least partially nest within the inner discrete portion.

16. The synchronous reluctance machine of claim 12, wherein the plurality of rotor poles comprises a plurality of laminations stacked in an axial direction of the rotor parallel to the axis, wherein the plurality of laminations comprises a body portion stack of laminations, a first discrete portion stack of laminations, and a second discrete portion stack of laminations.

17. The synchronous reluctance machine of claim 12, wherein the first rotor pole of the plurality of rotor poles comprises a second lacing, wherein the second lacing is configured to radially bind the inner discrete portion, the outer discrete portion, the inner wedge, and the outer wedge to the body portion, and the second lacing is configured to electrically and magnetically isolate the body portion from the inner discrete portion and the outer discrete portion.

18. A method of manufacturing a synchronous reluctance machine, comprising: layering a first wedge and a first discrete portion radially outside a body portion of a rotor pole of a rotor, wherein the first wedge is configured to electrically and magnetically isolate the body portion from the first discrete portion; and

binding with a first lacing the first discrete portion and the first wedge to the body portion, wherein the first lacing is configured to enclose the first discrete portion and the first wedge in a radial direction and an axial direction relative to an axis of the rotor, an exterior surface of the rotor is disposed at an outer radius from the axis, and the first lacing is radially disposed between the outer radius of the rotor and the axis.

19. The method of claim 18, comprising:

layering a second wedge and a second discrete portion radially outside the first wedge and the first discrete portion, wherein the second wedge is configured to electrically and magnetically isolate the first discrete portion from the second discrete portion; and

binding with the first lacing, the first discrete portion, the second discrete portion, the first wedge, and the second wedge to the body portion, wherein the first lacing is configured to enclose the first discrete portion, the second discrete portion, the first wedge, and the second wedge in a radial direction and an axial direction relative to the axis of the rotor.

20. The method of claim 18, comprising:

assembling the first discrete portion from a first plurality of laminations; and assembling the body portion from a second plurality of laminations.