Abstract: A self-contained momentum control system (MCS) for a spacecraft is provided for small satellites. The MCS features a miniaturized gyroscopic rotor with a rotational speed in excess of 20,000 RPM. The MCS includes at least three control moment gyroscopic mechanical assemblies (CMAs) rigidly mounted within a single enclosure, where each CMA mounted in an orientation whereby the longitudinal axis of each CMA is either orthogonal to every other CMA or is parallel to another CMA but in the opposite orientation. In order to further reduce the size of the MCS, an electronics package that is configured to interface command and control signals with and to provide power to the CMAs is included within the MCS enclosure. A plurality of shock isolation devices are used to secure each of the CMAs to the enclosure in order to reduce the launch load upon the CMAs thereby allowing the use of smaller rotor spin bearings. The MCS enclosure surrounding the CMAs and support structure is hermetically sealed.

Abstract: A miniature fan includes a housing having a mounting portion with a shaft seat. A base is mounted to the mounting portion of the housing. The base includes first and second faces spaced along an axis. An outer layer is provided on the first face of the base. A bottom layer is provided on the second face of the base. The base further includes a coil unit intermediate the outer layer and the bottom layer. The coil unit is electrically connected to a drive circuit. An impeller includes a shaft and a permanent magnet. The shaft is coupled to the shaft seat of the housing and rotatable about the axis. The permanent magnet is aligned with the coil unit. The axial height of the miniature fan is reduced, and the structure of the miniature fan is simplified.

Abstract: A stator for a brushless DC motor includes a cylindrical member and a positioning member. The cylindrical member is formed by a plurality of metal wires. Each metal wire includes two ends each forming a terminal. The cylindrical member includes first and second ends separated along a longitudinal axis. The positioning member includes an annular body received in the first end of the cylindrical member and separated from the second end of the cylindrical member along the longitudinal axis. The positioning member maintains a shape of the cylindrical member. The stator can be mounted in a space defined by a housing and a base engaged with the housing, forming a brushless DC motor. A bearing and a circuit board are mounted in the space. The bearing rotatably supports a shaft. A permanent magnet is mounted to the shaft and aligned with the stator.

Abstract: A motor with detachable winding assemblies includes a motor base, a shaft tube, a driving circuit board, a shaft, a plurality of winding assemblies and a rotor. Each winding assembly includes a base, a winding, a packaging body and two electrical connection members. The base includes a supporting face. The winding includes two ends and a plane, wherein the plane is in intimate contact with the support face of the base. The packaging body encloses the base and the winding. The two electrical connection members are respectively connected with the driving circuit board and the two ends of the winding, wherein each of the electrical connection members is partially exposed outside the packaging body. The rotor is rotatably coupled to the shaft.

Abstract: A stacking alternator includes a supporting frame, at least one stationary armature device securely supported by the supporting frame and at least two rotating magnetic devices rotatably supported by the supporting frame two sides of the stationary armature device respectively, wherein the rotating magnetic devices are arranged to be driven to move with respective to the stationary armature device so as to produce a relative movement between the stationary armature device and the rotating magnetic devices for generating a predetermined amount of electrical current at the stationary armature device, wherein the stationary armature device and the rotating magnetic devices are alignedly and spacedly supported by the supporting frame to form a stacking structure of the stationary armature device and the rotating magnetic devices.

Abstract: A method for producing a winding, particularly for electrical transformer from a cylindrical tubular metal element of polygonal cross-section, includes steps of machining, in a first series of passes, a first series of cuts substantially parallel to one another through all of the sides of the tubular element with the exception of a last one of said sides, and machining, in a second series of passes, a second series of cuts in said last one of said sides in order to ensure that junctions of the first series of cuts open out in the sides adjacent to the second series of cuts, so that the first and second series of cuts are continuous with respect to one another and constitute a single groove of helicoidal shape.

Abstract: The motor of an anti-lock braking system comprises a stator having six stator poles and a rotor with a rotor core having nine teeth. The rotor is rotatably mounted to the stator with the rotor core confronting the stator poles. Rotor windings are wound about the teeth and electrically connect to a commutator fixed to a rotor shaft. A bearing is fixed onto one end of the rotor shaft. Pump pistons radially attach to the bearing. The mechanical centreline of the bearing is offset from the rotational axis of the rotor shaft so that the pistons are driven by the bearing when the rotor turns. The windings comprise a plurality of concentrated coils so that the coils do not overlap with each other. The axial length of the motor is thus reduced.

Abstract: A rotating electromagnetic apparatus has a stator frame supporting spaced apart pairs of permanent magnets which are arranged with like magnetic poles mutually facing. A toroidally shaped rotor frame is radially wound with a plurality of wire coils immersed within slots in the in rotor frame, the slots positioned adjacent to the opposing magnets. An electromechanical commutator is used to direct current between an outside source or sink through brushes to rotating multiple contacts simultaneously. The brushes are triangular in cross section. The coils may be connected in series or parallel interconnection.

Abstract: A series of elongated oval wire windings bent into open C-shaped or other loop shape coils are positioned around a flywheel. Magnets, mating the loop opening shape, extend from the outer edge of the flywheel on a thin disc to pass through the coils to generate electricity with the spin of the flywheel. With no magnetic material is the coils there is no magnetic resistance created thereby providing more efficient electricity generation.

Abstract: There is provided a 3-phase 2-layer armature winding of a rotating electrical machine. The lead-out connection conductor connected to the output terminal is connected to a coil piece positioned at least farther than a first coil piece inside the phase belt counted from the end of the each phase belt, and a coil piece positioned at the end of the phase belt is connected to a coil piece positioned at least farther than the n-th (n is an integer larger than 1) inside the phase belt counted from the other end of the phase belt in the same parallel circuit, by a jumper wire.

Abstract: In a distribution winding stator using a coil for a rectangular conductor, a coil end is made smaller than before, and the reduction in the current density is aimed, so that a rotary electric machine of a small size and a high power output is obtained. A conductive wire of a rectangular shape in cross section is double-wound, and is allowed to be shifted by the whole width of the wire having double-wound the crowns of both ends, and is formed to crank shape so as to become a length within the range of the intervals of the adjacent slots, so that the conductive wire is formed by being inserted into the slot of the stator.

Abstract: A rotating electric machine for driving a vehicle includes: a stator that comprises a stator core in which a plurality of slots extending in a direction of a rotation axis are arranged circumferentially and a stator coil inserted into the slots; and a rotor that is rotatably provided in the stator through a gap, wherein: the stator coil is constituted with conducting wires, and a cross section of a protruding portion of each of the conducting wires that protrudes from the slots in a coil end portion of the stator coil is formed into a substantially trapezoidal shape.

Abstract: A method of producing a stator for a rotary electrical machine comprising a body in which axial recesses are produced and comprising a plurality of conductors arranged in the recesses, which comprises a step of depositing conductors on a linear support that comprises transverse recesses, comprising a first phase of depositing conductors in the recesses in the support in order to form a first layer of conductors, and a second phase of depositing conductors in the recesses, in order to form a second layer of conductors that is arranged vertically above the first layer; the first deposition phase and the second deposition phase consists of depositing one and the same conductor on the linear support. The invention also proposes an arrangement of a set of conductors on a linear support obtained at the end of the deposition step.

Abstract: A total number of windings in an armature is an even number. The windings are divided into a first winding group and a second winding group. The windings of the first winding group are arranged one after another at generally equal angular intervals without overlapping with each other. The windings of the second winding group are arranged one after another at generally equal angular intervals without overlapping with each other and are wound separately from the windings of the first winding group.

Abstract: A cassette coil comprising an insulator bobbin including a core tube around which a wire coated with an insulating film is wound, forming a coil, and a pair of plate-shaped flanges provided at both ends of the core tube, the flange including a cutout portion opening in a side, wherein the cassette coil includes an insulation wall between a winding start part which is one end of the coil of the wire and an outermost wire part located on the outermost side of the coil of the wire and close to the flange.

Abstract: A high-output and highly efficient axial gap type rotating machine capable of reducing an eddy current generated in a winding wire and supplying a larger current is provided.

Abstract: An apparatus comprises a rotor supported for rotation about a longitudinal axis. The rotor comprises an elongate tubular member enclosing a substantially cylindrical space, the elongate tubular member having a first open end defining an inlet, and a second open end defining an outlet. The apparatus includes at least one electrically conductive element for generating a magnetic field when electric current flows therethrough and for controlling rotation of the rotor. At least a part of at least one said electrically conductive element is aligned axially with at least a part of said elongate tubular member. The elongate tubular member comprises conveying means adapted so that upon rotation of said rotor, at least one body is caused to move in a direction from said inlet toward said outlet, through the substantially cylindrical space.

Abstract: A permanent-magnet synchronous motor of a draining pump is disclosed. It includes a permanent-magnet rotor for driving an impeller to rotate, a pump body for supporting the permanent-magnet rotor, a stator core and a stator coil. Among which, the stator coil is constructed with an enamelled aluminum wire winding which is coiled by an enamelled aluminum wire and sealed in a container. The invention applies the enamelled aluminum wire to the permanent-magnet synchronous motor of a draining pump. The winding of the stator coil and a welding part of its lead-out wire are sealed with plastic or epoxy resin which effectively isolate them from outside air, especially damp air. Therefore, the invention prevent the enamelled aluminum wire winding of the stator coil and the welding part of its lead-out wire from being oxidized in air and being corroded by the moisture, acid or alkaline matter in damp air.

Abstract: A stator coil includes a belt-shaped winding band and a same-layer bridging portion. The winding band makes one or more rounds, while turning back in the axial direction a plurality of conductor wires which are aligned in parallel at a pitch of electric angle ? (pi). The same-layer bridging portion connects a pair of the conductor wires which are of the same phase at the end portion of the winding and which are arranged in the same layer of the slot. Such arrangement enables forming a compact multi-phase stator coil.

Abstract: The present invention provides an improved single-layer coil 10 for a rotating or linear electrical machine. The coil 10 has a first endwinding 12 that is substantially parallel to a longitudinal axis LA of the coil and a second endwinding 14 that is bent away from, or towards, the longitudinal axis. The coil 10 therefore has differently shaped endwindings with one end 12 being ‘straight’ and the other end 14 being ‘bent’.

Abstract: The invention relates to a stator for an electric motor comprising several poles (P) that are directed inwards towards the motor axis (2) and that surround a rotor (1), each pole (P) being provided with one winding (L) and the coils of the windings (L) being wound around the poles (P) one after the other without interruption. The stator (20) contains at least three pole groups (n), having at least three poles (P) and each group having the same number of poles (P). The windings (L) run out from the end face at least at the respective beginning and end of a pole group and are contacted there in such a way that the windings (L) associated with each pole group contain their own connection pair (U-U?, V-V?, W-W?) and one connection (U?, V?, W?) of each of these connection pairs is connected to a star point (Y) on the end face of the stator (20).

Abstract: A split stator for an electric motor includes a core having a tooth portion, a coil formed around the tooth portion, insulation spacers arranged between a surface of the tooth portion and an inner periphery of the coil, and holding the inner periphery of the coil with a space kept from the surface of the tooth portion, and a resin filler material having high thermal conductivity and filling the space. The resin filler material is configured to allow heat release from the inner periphery of coil to the core.

Abstract: An armature including magnetic cores arranged on a surface of a plate, coils provided around the magnetic cores, and a magnetic material plate having a plurality of first magnetic members is characterized in that the magnetic material plate is attached to a surface on the opposite side to a surface where the magnetic cores and the plate come in contact, a gap is provided between each of the first magnetic members adjacent to each other, and the area of a surface where the first magnetic members come in contact with the magnetic cores is larger than the area of a surface where the magnetic cores come in contact with the first magnetic members.

Abstract: A distributed coil stator (102) for external rotor electric motors includes a core having a cylindrical surface bounded by a first end surface and a second end surface, wherein a first set of openings (110) aligned in a first circular path (111) extends within the core from the first end surface to the second end surface, a second set of openings (114) aligned in a second circular path (115) positioned concentrically within the first circular path extends within the core from the first end surface to the second end surface, and a third set of openings (118) aligned in a third circular path (119) positioned concentrically within the second circular path extends within the core from the first end surface to the second end surface.

Abstract: The present invention relates to an electromotive part of an elevator drive, comprising a rotor (24) and a stator (10, 22), wherein windings of the stator and/or the rotor (24) are provided as single tooth windings. An electromotive part of an elevator drive, is provided as an internal rotor motor, and includes a rotor and a stator. Windings of the stator and/or the rotor are provided as single tooth windings, the windings are, at least in part, encapsulated, and the windings are provided as two-layer windings. A method for winding-up windings of an electromotive part of an elevator drive with two-layer windings, includes inserting the windings of individual phases as alternating upper and lower layers.

Abstract: An object of the present invention is to provide a small, high-power rotating electrical machine by suitably forming a distributed winding coil such that two stator magnetic poles each formed of in-phase coil turns are arranged within an electric angle of 360 degrees formed by magnetic poles of the rotor. The present invention provides a method for manufacturing a stator, the method including a first step of placing a distributed winding coil 207 composed of a wire wound around a reel 210, as a whole, inside a stator core 202, and a second step of moving an insertion blade 213 so as to spread the distributed winding coil 207 in the radial direction of the stator core 202, thus inserting the distributed winding coil 207 into a stator core slot 206.

Abstract: A coil module for a stator of an electric motor comprising a coil holder, a coil that is disposed on the coil holder, a first web and a second web is provided, wherein situated between the first web and the second web are a first coil portion and a second coil portion for contacting with a motor circuit.

Abstract: An electromagnetic device includes a plurality of coils formed by winding conductors. At least some of the conductors are constructed by stacking conductor constructional elements so that an eddy current generated by a leakage flux linked to the conductor is divided. An outer insulating member is disposed on an outer circumferential surface of the conductor stack for electrically insulating the conductor stack from another member. An inner insulating member whose thickness is smaller than a thickness of the outer insulating member is disposed between the conductor constructional elements adjoining to each other in the same conductor stack.

Abstract: A stator of an electrical machine operable as a motor or a generator, applicable to a radial-axial type machine. The stator includes a plurality of stator segments disposed circumferentially about an axis. Each segment has a generally wedge shaped core and a winding wound around the core. The winding is bent to have portions that are disposed on multiple planes. The core includes an elongated wedge tip portions aligned parallel to the axis and an outer radial face opposite to the tip portion. The multiple planes include at least one plane substantially normal to the axis and at least one plane tangential to the radial face.

Abstract: An actuator includes: a coil for excitation; a rotor rotatably supported; a stator effecting a magnetic force on the rotor for rotation, the stator having first and second leg portions arranged side by side; and first and second coil frames each having a body portion and a pair of flange portions provided at an end of the body portion. The first coil frame is assembled onto the first leg portion. The second coil frame is assembled onto the second leg portion. The first and second coil frames are connected via a connecting portion bendable. The body portions are arranged not to be sandwiched between the first and second leg portions. Each of the body portions covers a halfway or less of each of peripheral surfaces of the first and second leg portions of the stator.

Abstract: The object of the invention is a method for manufacturing a winding coil for an electrical machine, as well as the corresponding winding. The electrical machine comprises a stator sheet pack in which slots are arranged at the edge of the inner circumference of the sheet pack for fitting the winding coils. In the method, a winding coil is made of flat wire so that one coil turn (42, 44) goes around a tooth (2) between adjacent slots. According to the invention, the coil turns (42, 44) are manufactured so that one coil end (46) is bent substantially close to the edge (50) of the sheet pack, and a second coil end (60) is bent at a distance from the edge (50) of the sheet pack. The first and second coil end bent at different positions are fitted to the slot one on top of the other around the tooth (2).

Abstract: A rotating electrical machine stator comprising an annular cylindrical body including axial grooves, and at least one phase winding including corrugated turns of wire, the phase winding comprising a first outer half-phase and a second inner half-phase which are radially superimposed, the first outer half-phase including outer leading-out wires projecting from the radial walls of the body and the second inner half-phase including outer leading-out wires projecting from the radial walls of the body. The invention is characterized in that for each phase winding, the wire length of each turn of the inner half-phase is greater than the wire length of each turn of the outer half-phase. The invention also concerns a phase winding designed to be mounted in such a rotor.

Abstract: In a method for the mechanical winding of a coil (1) having at least one wire (4), the coil (1) comprising a coil inner side (14) and at least two winding layers (2), one winding layer (2) being formed by turns (5) situated essentially parallel to the coil inner side (14), to increase the precision of the winding and to reduce the dimensional tolerances of the winding, it is proposed at least during the winding of a first winding layer (21), at a predefinable position between a first turn (54) and a second turn (55) adjacent to the first turn (54), the second turn (55) being wound immediately following the first turn (54), a gap (6) is implemented, the width of the gap (6) at least regionally being at least one wire diameter, and the wire (4) is guided into the gap (6) after the winding of the second turn (5), and optionally after the winding of further turns (5), at least one support turn (51) being implemented.

Abstract: A base plate for magnetic disk drives is provided that includes a hooked protrusion integrated therein between adjacent spindle motor coils. The cross-over wires that span between adjacent coils are secured by the hooked protrusions, thereby optimizing coil height and reducing manufacturing steps. The hook-like protrusions of one embodiment of the present invention are preferably stamped into the base plate.

Abstract: A winding apparatus for a segmented core having a plurality of stator teeth includes a mounting fixture configured to support select ones of the plurality of stator teeth. The mounting fixture is configured to rotate about an axis defined by each of the plurality of stator teeth. The winding apparatus also includes a plurality of stator tooth holding elements operatively connected to the mounting fixture. Each of the plurality of stator tooth holding elements are configured to retain a select one of the plurality of a stator teeth relative to the mounting fixture. The mounting fixture is selectively rotated about the axis of at least one of the plurality of teeth to apply wraps of wire to the one of the plurality of stator teeth while at the same time rotating others of the plurality of stator teeth that have already been wrapped with wire.

Abstract: An integrated motor, integrated to a structural part and an electronic substrate of an electronic device, includes a base formed on the structural part of the electronic device, a rotor having a load, and a stator having a plurality of winding coils and a driving circuit respectively shaped on the electronic substrate of the electronic device, for driving the rotor to rotate in a specific direction.

Abstract: A design for and method of winding an electric motor, generator or other electrical machine using multiple strands of wire preformed into a wave shape with a plurality of legs connected by shaped end turns. This results in efficient packing and improved machine performance in terms of both efficiency and power density without the need for flux concentrators. The conductors or windings may be preformed so as to be a self supporting structure, aiding assembly and eliminating the need for an iron core.

Abstract: The invention includes an electric machine having a rotor, a stator and at least one electrical coil disposed in the machine and a source of coolant fluid in communication with the coil. The coil has concentric turns having spaces therebetween adapted to channel coolant flow between the concentric turns.

Abstract: A technique for winding multi-turn, stranded wire coils using rectangular cables avoids the risk of damage associated with edge-wise bends.

Abstract: A method to form a field winding for a slotless stator including: forming the first coil group by spirally winding an insulated wire for each coil winding around a mandrel such that each turn of the wire is adjacent a next turn of the wire; after forming the first coil group, axially shifting along the mandrel the insulated wire from a trailing edge of each coil winding to position the wires at a leading edge of each of coil winding in the second coil group; forming the second coil group by spirally winding the insulated wire for each coil winding around a mandrel; removing the mandrel from the wound first and second coil groups; collapsing the wound coil groups to a layer web such that coil winding segments are interleaved; and wrapping the web into a cylinder to form the field winding.

Abstract: This invention presents a highly efficient electric motor which can he embodied in several configurations, including a standard motor, a hub motor, a linear motor, or other motor configuration. As a regenerative device, the motor may also act as a part-time or full-time electrical generator. There is provided a motor composed of a stator and a rotor. The stator has an array of coils arranged therein. The rotor has an array of magnets arranged therein. Each of the coils includes a first winding of wire wrapped around a core, and the wire has a non-circular cross-section. The wire can be a flattened wire.

Abstract: A method for mounting coil onto stator for rotary electric machine. The method includes forming coil pieces by winding wire with flat cross section into single row lamination state including wire layers aligned along perpendicular line to flat surfaces of wire. The coil is formed for first portion to be inserted in slot and second portion not inserted in slot appear alternately along the coil. The method displaces wire layers at the first portion changing the single row lamination state to connectively laminated state where wire layers at portion to be inserted in slot each adjacent pair of the wire layers partially overlap with respect to direction perpendicular to flat wire surfaces. The method includes inserting wires of first portion into slot, passing each wire layer through slot opening successively from the top wire layer of lamination and displacing each wire layer at first portion from each other.

Abstract: A method is disclosed for manufacturing a motor stator including: a stator core 30 provided, in an inner surface thereof, with a plurality of slots 32 and a plurality of teeth 31 each radially inwardly extending and tapering toward the center of the stator core, the teeth including at least a first tooth 31A, a second tooth 31B, and a third tooth 31C, and the slots and the teeth being arranged alternately; and a plurality of trapezoidal coils 10 each of which is inserted in each slot, each coil being formed of a rectangular conductor 15 that has a square section and is concentrated-wound into a trapezoidal shape.

Abstract: In a stator winding method for winding conductive wires 8 around teeth 4a to 4f of a stator core 4 having 3n teeth 4a to 4f and 3n slots 5a to 5f by use of a bobbin machine 12 having three nozzles 13, the slots 5a to 5f on both sides of the teeth 4a, 4d, 4f in the nth winding process are formed, in respective slot portions on the side of the teeth 4a, 4d, 4f in the nth winding process, so that respective depths “A” are all smaller than respective depths “B” of the remaining portions. At the final stage of the nth winding process, the nozzles 13 are moved from the interior side of the slots 5a to 5f toward the inner circumferential side of the stator core 3 and furthermore, the conductive wires 8 are wound around the teeth 4b, 4d, 4f so that each gap 14 between the conductive wires 8 wound around the teeth 4b, 4d, 4f and the conductive wires 8 wound around the teeth 4a, 4c, 4e is smaller than an outer diameter of the nozzle 13.

Abstract: A stator assembly for a dynamoelectric machine featuring a cascaded construction includes several conductors, each having a plurality of slot segments interconnected by plurality of end loop segments. The consecutive slot segments of a first conductor forms nearly all of a radially-outermost first layer of the stator winding, with the remaining portion of the radially-outermost winding layer being defined by a slot segment of a second conductor that is then inserted into the core to form nearly all of a second layer of the stator winding radially-inwardly of the first winding layer. The second winding layer is completed with an additional single slot segment of the first conductor.

Abstract: A method for producing a coil winding for stators is described, in which each coil turn rests, with one fillet (14) each, in two stator slots, and the two fillets (14) are joined by a head portion (16). A plurality of coil turns are made simultaneously by winding up n parallel wires (10) with intermediate spacing onto a rotatable former (20). To obtain small winding heads, alternatingly in a work step A, one fillet (14) and the wire length of one head portion (16) are made from each of the parallel wires (10) on the former (20). Then in a work step B, the resultant fillets (14) together with the adjoining first end of the respective associated head portions (16), and the wire guide together with the second end of these head portions (16), are displaced relative to one another along the former (20) by n times the intermediate spacing of the wires (10). After work steps A and B have been repeated multiple times, the fillets (14) for the last n stator slots are then also made on the former (20).

Abstract: An electric motor is disclosed with an air-cored winding which is composed of a plurality of single coils made of wire, wherein the single coils overlap each other in an imbricated manner and the single coils are preformed to form an offset at least in the region of two opposite corners, so that half of the legs are located in a first plane and half of the legs are located in a second plane. A more inexpensive and more robust assembly of air-cored windings for electric motors can thereby be achieved.

Abstract: A rotating electric machine includes a stator core of a cylindrical shape, a rotor core coaxially rotating inside the stator core, and a plurality of coils each formed by winding magnet wires using a slot formed axially in either the stator core or the rotor core, or both: it is preferable that each of the coils be split into a plurality of coil groups, that starting sections of winding of the magnet wires in one of the coil groups be wound adjacently to ending sections of winding of the magnet wires in another of the coil groups, and that the starting sections and ending sections of winding of the magnet wires in the two coil groups be connected at respective outgoing wire ends to one another, outside the slots.

Abstract: A coil production method capable of improving the space factor of a rectangular conductor with respect to the slot of a stator core, a coil of a motor, and a stator of a motor. The coil production method in which one surface of a rectangular conductor is brought into contact with a shaft with guide, and edgewise bending is performed along the curved surface of the shaft, wherein a deforming mechanism for reducing the plate thickness of a plate thickness changed portion corresponding to each of four corners of a coil over the entire width of the rectangular conductor is provided, the deformation mechanism is used to deform the plate thickness changing portion, and the plate thickness changing portion of the rectangular conductor is edgewise-bent to form a coil.

Abstract: A stator for an electric machine includes multiple conductive coils. Each coil defines a loop that extends axially through the elongate core, exits the core through an end face, and reenters the core through the end face. A first subset of the coils collectively form a first radial layer axially exterior the core and a third radial layer axially exterior the core. Each coil in the first subset resides in both the first layer and the third layer. A second subset of the coils collectively forms a second radial layer axially exterior the core and a fourth radial layer axially exterior the core. Each coil in the second subset residing in both the second layer and the fourth layer.