Electromagnet design for high magnetic FLUX applications

Abstract

An electromagnet (200) includes a cylindrical core (204) and a bobbin (210). The bobbin (210) has a first barrel portion (212) delimited by a first flange (216) and a second flange (218), and a second barrel portion (214) delimited by the second flange (218) and a third flange (220). A diameter of the first flange (216) is greater than a diameter of the third flange (220). The bobbin (210) also includes an aperture (228) extending through the first and second barrel portions (212, 214), wherein the core (204) is disposed within the aperture (228). A wire (230) is wrapped around the first barrel portion (212) to define a first portion (234) of a coil (232) and around the second barrel portion (214) to define a second portion (236) of the coil (232). A power source provides current through the wire (230).

Description

ELECTROMAGNET DESIGN FOR HIGH MAGNETIC FLUX APPLICATIONSBACKGROUND[1] Magnets have a wide range of applications in the modern-day world such as brakes, motors, and generators. They can generally be classified into permanent magnets and electromagnets. Permanent magnets generally retain their magnetic strength once magnetized and act as a direct source of magnetic fields. In contrast, electromagnets utilize a coil, which typically surrounds a magnetic core, and a current source to create a magnetic field. Because magnetic fields produced by electromagnets are active only when an electrical current is passing through the coil, electromagnets can selectively be switched between “on” and “off’ states by controlling the flow of current through the coil.[2] For magnetic machines, such as the previously mentioned brakes, motors and generators, etc., the magnetic field strength provided by the associated magnets is an important factor with respect to machine performance. Such machines often utilize a magnetic array to provide high-power magnetic fields. A magnetic array typically consists of a series of permanent magnets, electromagnets, or a combination of both. One example of a popular configuration for a magnet array is the Halbach array, which is a specific arrangement of magnets that augments the magnetic field on one side of the array. The usage of such arrangements of magnets varies by application and magnetic flux requirements. Hybrid arrays are magnetic arrays having a combination of permanent magnets and electromagnets. These arrays have flexibility to augment or limit the magnetic flux output from a machine.[3] When a current carrying wire is wrapped around a cylindrical ferromagnetic body, a magnetic field is induced in that body. Multiple loops of the wire wrapped around the core are collectively referred to as a solenoid. The magnetic field strength in the ferromagnetic body, also known as the core, is the sum of the fields produced in each individual loop of the solenoid. The flux produced by a current-carrying solenoid is dependent on the number of turns and the magnitude of current inside the wire. Therefore, increasing the number of coils increases the maximum flux density in the core, up until the magnetic saturation limit of the core itself. The generated flux is channeled through a pole shoe at the end of the core, which is often an effective indicator of magnetic flux output.[4] FIGURE 12 shows a schematic view of an electromagnetic device 50. The electromagnetic device 50 includes a housing 52 with a rotor 54 mounted to an axle 56 forrotation about an axis 58. The rotor is formed at least in part by an electrically conductive material. A corresponding stator 60 is mounted within the housing 52 and is fixed in rotation. The stator produces an electromagnetic field. As the rotor moves through the electromagnetic field, eddy currents are generated in the stator, resulting in drag, i.e., a braking force, on the rotor.SUMMARY[5] The present disclosure provides examples of an electromagnet and an electromagnetic filed array that utilizes one or more of these electromagnets. In an embodiment, the electromagnet comprises a core and a bobbin. The bobbin has a first barrel portion delimited by a first flange extending radially from a first end of the first barrel portion and a second flange extending radially from a second end of the first barrel portion. A second barrel portion of the bobbin is delimited by the second flange at a first end of the second barrel portion and a third flange extending radially from a second end of the second barrel portion. A diameter of the first flange is greater than a diameter of the third flange. An aperture extends through the first barrel portion and second barrel portion, and the core is disposed within the aperture. A wire is wrapped around the first barrel portion to define a first portion of a coil and around the second barrel portion to define a second portion of the coil. A power source provides current through the wire.[6] In any embodiment, the electromagnet further comprises a pole shoe disposed at an end of the core.[7] In any embodiment, a diameter of the first portion of the coil is greater than a diameter of the second portion of the coil.[8] In any embodiment, a slot is formed in the second flange and extends outwardly from the first barrel portion, and the wire extends through the slot between the first coil portion and the second coil portion.[9] In any embodiment, the slot is tangential to the first barrel portion.

[0010] In any embodiment, an electromagnetic array comprises an annular support and a disclosed electromagnet, wherein the pole shoe is coupled to the annular support.

[0011] In any embodiment, the electromagnetic array further comprises a shim disposed between the pole shoe and the annular support.

[0012] In any embodiment, the annular support comprises an internal splined surface.

[0013] In any embodiment, the annular support further comprises an annular base and a plurality of permanent magnets coupled to the base.

[0014] In any embodiment, each of the permanent magnets includes a recess and / or a cutout, and the annular base includes a ridge extending radially into the recess and / or the cutout of each permanent magnet.

[0015] In any embodiment, the permanent magnets and the pole shoe cooperate to define a flat surface.

[0016] In any embodiment, an electromagnetic array comprises an annular support and a plurality of a disclosed electromagnet, wherein the pole shoe of each electromagnet is coupled to the annular support.

[0017] In any embodiment, the electromagnets of the plurality of electromagnets are evenly spaced around the annular support.

[0018] In any embodiment, a shim is disposed between each pole shoe and the annular support.

[0019] In any embodiment, an electromagnetic brake comprises a stator that includes a disclosed electromagnetic array.

[0020] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.DESCRIPTION OF THE DRAWINGS

[0021] The foregoing aspects and many of the attendant advantages of the present disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0022] FIGURE 1 is a front isometric view of an electromagnetic array according to aspects of the present disclosure;

[0023] FIGURE 2 is a rear isometric view thereof;

[0024] FIGURE 3 is a partially exploded front isometric view thereof;

[0025] FIGURE 4 is a partially exploded rear isometric view thereof;

[0026] FIGURE 5 is a rear elevational view thereof;

[0027] FIGURE 6 is a partial cross-sectional view thereof as indicated in FIGURE 5;

[0028] FIGURE 7 is a partial cross-sectional view thereof as indicated in FIGURE 5;

[0029] FIGURE 8 is a rear isometric view of an electromagnet assembly of the electromagnetic array shown in FIGURE 1 ;

[0030] FIGURE 9 is a side elevational view of the electromagnet assembly of FIGURE 8 with the covers removed;

[0031] FIGURE 10 is a rear isometric view of a core and a pole shoe of the electromagnet assembly of FIGURE 8;

[0032] FIGURE 11 is a front isometric view of a bobbin of the electromagnet assembly of FIGURE 8; and

[0033] FIGURE 12 is a schematic view of an electromagnetic device that includes a rotor and a stator.DETAILED DESCRIPTION

[0034] The detailed description set forth below in connection with the appended drawings, where like numerals reference like elements, is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed.

[0035] The following discussion provides examples of an electromagnet and an electromagnetic array that is used as a stator for various electromagnetic devices, including “eddy current,” i.e., electromagnetic brakes. Embodiments of the electromagnetic brakes may be used on vehicles and in particular, aircraft, wherein a high magnetic flux is required to be produced in a limited space.

[0036] FIGURE 1 through FIGURE 7 show a representative embodiment of an electromagnetic array 100 (hereinafter “array 100 or “array”) according to aspects of the present disclosure. As best shown in FIGURES 1 and 2, the array 100 includes a generally annular support 110 having a plurality of electromagnets 200 mounted thereto. In the illustrated embodiment, the array 100 includes four electromagnets 200 arranged in an evenly spaced circular pattern, i.e., at approximately 90° intervals. In any embodiment thenumber and position of electromagnets 200 can vary in any suitable manner. In any embodiment, the array may include one, two, three, five, or any other suitable number of electromagnets 200. In any embodiment, the electromagnets 200 may be evenly spaced or unevenly spaced around the support 110. In any embodiment, the electromagnets may be different radial distances from the center of the support 110.

[0037] As will now be described, in addition to providing a mounting structure for the electromagnets 200, the support 110 also provides a locking feature to fixedly position the array 100 in rotation so that the array can be utilized as a stator in an electromagnetic device. Further, in the illustrated embodiment, the support 110 includes a plurality of permanent magnets that cooperate with the electromagnets to provide a “hybrid” array 100.

[0038] As best shown in FIGURES 3 and 4, the support 110 includes an annular base 120. The base 120 has a generally flat, annular base plate 122 with an internally splined feature extending through a central portion thereof. The splined feature 124 is sized and configured to engage a complementary external spline of the electromagnetic device on which the array 100 is utilized. Engagement of the splined feature 124 with the complementary surface of the electromagnetic device fixes the array 100 in rotation so that the array acts as a stator. In some embodiments, the splined feature is an external spline that engages an internal splined fixedly positioned in rotation. In some embodiments, the support is secured in rotation by any suitable mounting configuration or locking mechanism.

[0039] A plurality of apertures 126 extend through base plate 122. The apertures 126 are sized and positioned so that for each aperture, a corresponding electromagnet 200 mounted to the support 110 extends through the aperture.

[0040] As best shown in FIGURE 3, an annular ridge 128 extends radially outward from an external portion of the splined feature 124. The ridge 128 is parallel to and offset from the base plate 122. The portions of the ridge 128 proximate to the apertures 126 extend further in the radial direction to define mounting features 130 to which the electromagnets 200 are secured.

[0041] Still referring to FIGURE 3, the support 110 includes a permanent magnet assembly 140 (hereinafter “magnet assembly 140” or “magnet assembly”). The magnet assembly 140 includes a plurality of tapered permanent magnets 142, each magnet having an arcuate inner surface 144 having a first diameter and an arcuate outer surface 146 having a second diameter greater than the first diameter. A recess 148 is formed along the innersurface 144 of each magnet and is sized and configured to receive a portion of the ridge 128 of the base 120. A plurality of magnets 142 is arranged in seriatim to form a portion of an annular magnet that extends between adjacent mounting features. When the plurality of magnets 142 is arranged in this manner, the recesses 148 of the magnets are aligned to form a single recess that receives a portion of the ridge 128 of the base 120. It will be appreciated that the number, size, and configuration of one or more of the magnets 142 can vary in any suitable matter.

[0042] An outer ring 160 has a generally cylindrical body 162 with an inner surface sized to engage the outer surface 146 of each of the magnets 142 of the magnet assembly 140 when the array 100 is assembled. The outer ring also includes a plurality of arcuate retention features 164 arranged such that each retention feature engages and provides support to one of the electromagnets 200 mounted to the support 110. As shown in FIGURES 3 and 4, the outer ring 160 is secured to the base 120 with a plurality of fasteners 180.

[0043] Referring now to FIGURE 7, when the array is assembled, a portion of the ridge 128 extends into the recess 148 of each magnet 142 of the magnet assembly 140 and a face of each magnet 142 is in contact with the base plate 122. For each magnet 142 this engagement with the ridge 128 and the base plate 122 restrains movement of the magnet 142 in the axial direction. At the same time, for each magnet 142, engagement of the inner surface 144 with the ridge 128 and / or other portion of the base and engagement of the outer surface 146 with an inner surface of the outer ring 160 restrains movement of the magnet 142 in the radial direction. As a result, the magnet assembly 140 is fixedly positioned relative to the base 120.

[0044] As shown in FIGURES 3 and 6, a backplate 150 is mounted to the base 120 opposite the magnet assembly 140. The backplate 150 includes an annular plate 152 having a planar face abutting a planar face of the base plate 122. A plurality of arcuate recesses 154 extend from an inner surface of the annular plate 152. The recesses 154 are sized and configured to align with the apertures 126 formed in the base 120. When the support 110 is assembled and the electromagnets 200 are mounted to the support 110, each electromagnet 200 extends through one of the apertures 126 formed in the base 120, as well as the corresponding recess 154 in the backplate 150. The backplate 150 provides additional strength and structural integrity to the base 120. In addition, each of therecesses 154 in the backplate engages a portion of the corresponding electromagnet 200 to further restrain movement of the electromagnet relative to the support 110.

[0045] It will be appreciated that the disclosed support is exemplary only and should not be considered limiting. In some embodiments, the portions of the support may be integrally formed. In some embodiments, the size, number, and shape of the permanent magnets may differ. In some embodiment, the permanent magnets and / or electromagnets are coupled to the support in different ways. These and other variations are contemplated and should be considered within the scope of the present disclosure.

[0046] Referring now to FIGURES 8 through 11, an example embodiment of an electromagnet 200 according to aspects of the present disclosure will be described. The electromagnets 200. As best shown in FIGURE 10, the electromagnet 200 includes a pole shoe 202 disposed at the end of a cylindrical core 204. In some embodiments, the pole shoe 202 and the core 204 are formed from the same or different ferromagnetic materials. In some embodiments, the pole shoe 202 and / or core 204 are formed from iron or electrical steel. In some embodiments, the core 204 is not cylindrical. In this regard, the core 204 may have any suitable form, including cross-sections of different shapes, including but not limited to the profile of the pole shoe 202. In some embodiments, the core has varying lengths and or cross-sections. It will be appreciated that the core 204 can have any suitable configuration / shape, and such variations should be considered within the scope of the present disclosure.

[0047] The pole shoe 202 has a flat plate structure and is positioned at an end of the core 204 so that the centerline of the core is normal to the pole shoe. As shown in FIGURE 1, the pole shoe 202 has tapered sides configured to fit between and engage the sides of the adjacent magnets 142 when the electromagnet is installed on the support 110. The upper and lower sides of the pole shoe 202 each has an arcuate contour sized and configured to be disposed between the outer ring 160 and the outer portion of the splined feature 124. In some embodiments, a fillet 206 provides a transition between the pole shoe 202 and the core 204, as shown in FIGURE 10. In some embodiments, the pole shoe 202 is formed separate from the core 204 and coupled thereto using fasteners, welding, adhesives or any other suitable fastening methods or combinations of fastening methods. In some embodiments, the pole shoe 202 and the core 204 are integrally formed. In some embodiments, the pole shoe has any suitable shape / profile.

[0048] Referring to FIGURES 8 and 9, a shim 208 is positioned on the rear surface of the pole shoe 202, i.e., the side from which the core 204 extends, and along the bottom edge of the pole shoe. As shown in FIGURE 6, when the pole shoe 202 and, thus, the electromagnet 200 are mounted to the support 110, the pole shoe 202 is coupled to a corresponding mounting feature 130 of the base 120. In the illustrated embodiment, the shim 208 is clamped between the pole shoe 202 and the mounting feature 130, with a fastener 182 that extends through the pole shoe 202 and the shim 208 to threadedly engage the mounting feature 130. It will be appreciated that the position of the electromagnet 200 can be varied in the axial direction relative to the support 110 by changing the thickness of the shim 208. In some embodiments, more than one shim is used per electromagnet 200, and the position of the electromagnet 200 in the axial direction relative to the support 110 can be adjusted by varying the thickness and / or number of shims utilized. In some embodiments, any suitable type, number, and / or combination of fasteners or coupling means are utilized to secure the pole shoe 202 to the mounting feature 130.

[0049] As best shown in FIGURES 6, 9, and 11, the electromagnet 200 further includes a bobbin 210 mounted to the core 204. The bobbin 210 has a cylindrical first barrel portion 212 and a second barrel portion 214. An aperture 228 extends through the bobbin 210 and is sized to slidably receive the core 204.

[0050] The first barrel portion 212 is delimited by a first flange 216 extending radially from one end of the first barrel portion and a second flange 218 extending radially from the other end of the first barrel portion. The first flange 216 and the second flange 218 have the same or similar diameters.

[0051] The second barrel portion 214 is delimited by the second flange 218 which extends radially from one end of the second barrel portion, and a third flange 220, which extends from the opposite end of the second barrel portion. The third flange 220 has a diameter smaller than the first and second flanges 216, 218.

[0052] Referring now to FIGURES 6 and 9, an electrically conductive wire 230 is wrapped around the bobbin 210 to define a coil 232. The second flange 218 separates a first portion 234 of the coil 232 from a second portion 236 of the coil 232. The first portion 234 of the coil 232 is disposed between the first flange 216 and the second flange 218. The second portion 236 of the coil 232 is disposed between the second flange 218 and the third flange 220 and has a diameter that is smaller than the diameter of the first portion 234 of the coil 232.

[0053] As shown in FIGURE 11, slots 222 and 224 are formed in the first flange 216 and second flange 218, respectively. The slots 222 and 224 extend tangentially from the first barrel portion 212. The second flange 218 also includes a notch 226 extending radially inward from the outer edge of the flange.

[0054] Referring to FIGURES 6, 9, and 11, the wire 230 enters the bobbin 210 through the first slot 222 and wraps around the first barrel portion 212 in layers to form the first portion 234 of the coil 232. The wire then passes through the second slot 224 and wraps around the second barrel portion 214 in layers to form the second portion 236 of the coil 232. The tangential orientation of the first and second slots limits bending of the wire as it passes through the slots 222 and 224. The wire exits the bobbin 210 through the notch 226.

[0055] As best shown in FIGURES 6 and 8, a cylindrical first cover 240 extends from the first flange 216 to the second flange 218 and surrounds the first portion 234 of the coil 232. A cylindrical second cover 242 extends from the second flange 218 to the third flange 220.

[0056] The core 204 extends through the aperture 228 of the bobbin 210, which is secured to the pole shoe 202 and the core 204 by an end cap 244 coupled to the core 204. The pole shoe 202 and the end cap 244 are fixedly positioned relative to each other, and limit axial movement of the bobbin 210 in both directions relative to the core 204 so that the bobbin remains mounted to the core. In the illustrated embodiment, the end cap 244 is secure to the core 204 by a threaded fastener 246, but it will be appreciated that any suitable configuration for securing the end cape to the core can be utilized and such variations should be considered within the scope of the present disclosure.

[0057] As shown in FIGURES 8 and 9, the electromagnet 200 includes a pair of terminals 248 accessible from the outside of the electromagnet. Each terminal 248 is connected to one end of the wire 230 that forms the coil 232 of the electromagnet 200 so that one terminal serves as an input terminal and the other serves as an output terminal. The terminals are configured to be connected to a power source that provides a current to the coil 232 to power the electromagnet.

[0058] Referring back to FIGURES 1 and 2, the disclosed support 110 and electromagnets 200 cooperate to provide an electromagnetic array 100 in which the permanent magnets 142 and the pole shoes 202 cooperate to define a generally flat, annular forward face. The support 110 has a compact profile in the axial direction, and the geometryof the bobbin 210 maximizes the number of turns of the wire 230 within restricted areas. These features combine to provide a compact electromagnetic array 100 that produces increased magnetic flux output within a restricted envelope.

[0059] Referring back to FIGURE 12, the disclosed array 100 is suitable for use as a stator 60 for any number of electromagnetic devices 50. In some embodiments, the electromagnetic device 50 is an electromagnetic brake. In some embodiments, the electromagnetic brake is for an aircraft landing gear, and the array 100 is fixedly secured to an axle. In some embodiments, the electromagnetic device 50 is a motor, a generator, or any other suitable device. In some embodiments, the face of the array 100 is separated from a corresponding rotor. In some embodiments, a pair of arrays 100 face each other with a rotor disposed between the arrays.

[0060] The detailed description set forth above in connection with the appended drawings, where like numerals reference like elements, are intended as a description of various embodiments of the present disclosure and are not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result.

[0061] In the foregoing description, specific details are set forth to provide a thorough understanding of representative embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-known process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein. All such combinations or sub-combinations of features are within the scope of the present disclosure.

[0062] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also, in this regard, the present application may use the term “plurality” to reference aquantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The terms “about,” “approximately,” “near,” etc., mean plus or minus 5% of the stated value. For the purposes of the present disclosure, the phrase “at least one of A, B, and C,” for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when greater than three elements are listed.

[0063] It should be noted that for purposes of this disclosure, terminology such as “upper,” “lower,” “vertical,” “horizontal,” “fore,” “aft,” “inner,” “outer,” “front,” “rear,” etc., should be construed as descriptive and not limiting the scope of the claimed subject matter. Further, the use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings.

[0064] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0065] The drawings in the FIGURES are not to scale. Similar elements are generally denoted by similar references in the FIGURES. For the purposes of this disclosure, the same or similar elements may bear the same references. Furthermore, the presence of reference numbers or letters in the drawings cannot be considered limiting, even when such numbers or letters are indicated in the claims.

[0066] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure, which are intended to be protected, are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure as claimed.

Claims

CLAIMS1. An electromagnet (200), comprising: a core (204); a bobbin (210) having: a first barrel portion (212) delimited by a first flange (216) extending radially from a first end of the first barrel portion (212) and a second flange (218) extending radially from a second end of the first barrel portion (212); a second barrel portion (214) delimited by the second flange (218) at a first end of the second barrel portion (214) and a third flange (220) extending radially from a second end of the second barrel portion (214), wherein a diameter of the first flange (216) is greater than a diameter of the third flange (220); and an aperture (228) extending through the first barrel portion (212) and second barrel portion (214), wherein the core (204) is disposed within the aperture (228); a wire (230) wrapped around the first barrel portion (212) to define a first portion (234) of a coil (232) and around the second barrel portion (214) to define a second portion (236) of the coil (232); and a power source providing current through the wire (260).

2. The electromagnet (200) according to Claim 1, wherein a diameter of the first portion (234) of the coil (232) is greater than a diameter of the second portion (236) of the coil (232).

3. The electromagnet (200) according to Claim 1 or 2, wherein a slot (224) is formed in the second flange (218) and extends outwardly from the first barrel portion (212), wherein the wire (230) extends through the slot (224) between the first coil portion (234) and the second coil portion (236).

4. The electromagnet (200) according to Claim 3, wherein the slot (224) is tangential to the first barrel portion (212).

5. The electromagnet (200) according to any of Claims 1 to 4, further comprising a pole shoe (202) disposed at an end of the core (204).

6. An electromagnetic array (100), comprising:an annular support (110); and the electromagnet (200) according to Claim 5, wherein the pole shoe (202) is coupled to the annular support (110).

7. The electromagnetic array (100) according to Claim 6, further comprising a shim (208) disposed between the pole shoe (202) and the annular support (110).

8. The electromagnetic array (100) according to Claim 6 or 7, wherein the annular support (110) comprises an internal splined surface.

9. The electromagnetic array (100) according to Claim 8, wherein the annular support (110) further comprises an annular base (120) and a plurality of permanent magnets (142) coupled to the base (120).

10. The electromagnetic array (100) according to Claim 9, wherein each of the permanent magnets (142) includes a recess (148) and / or a cutout, and the annular base (120) includes a ridge extending radially into the recess (148) and / or the cutout of each permanent magnet (142).

11. The electromagnetic array (100) according to Claim 10, wherein the permanent magnets (142) and the pole shoe (202) cooperate to define a flat surface.

12. An electromagnetic array (100), comprising: an annular support (110); and a plurality of the electromagnet (200) according to Claim 5, wherein the pole shoe (202) of each electromagnet (200) is coupled to the annular support (110).

13. The electromagnetic array (100) according to Claim 12, wherein the electromagnets (200) of the plurality of electromagnets (200) are evenly spaced around the annular support (110).

14. The electromagnetic (100) array according to Claim 13, wherein a shim (208) is disposed between each pole shoe (202) and the annular support (110).

15. An electromagnetic brake comprising a stator that includes the electromagnetic array of any of Claims 12 to 14.

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