Abstract: An electrical machine comprising a rotor and a stator is provided. The stator includes a plurality of stator tooth modules configured for radial magnetic flux flow. The stator tooth modules include at least one end plate, and the end plates have extensions for mounting onto a stator frame. The stator is concentrically disposed in relation to the rotor of the electrical machine.

Abstract: The motor including a stator having a stator core, and an insulator provided to the stator core for winding a coil thereon, a rotor rotatably provided with respect to the stator, and a tap terminal provided to the insulator for positioning an end of the coil, wherein the coil includes a core wire of aluminum.

Abstract: Disclosed are a motor and a drum washing machine having the same. The motor includes external stators and internal stators, which are respectively disposed in a ring shape and are separated from each other in a radial direction, and rotors, which are disposed in a ring shape and are rotatably installed between the external stators and the internal stators such that the rotors are rotated due to interaction with the external stators and the internal stators, thus being capable of generating a high rotary force while maintaining a uniform length in an axial direction.

Abstract: A machine useful for ship propulsion purposes include a double-sided generator or motor with two concentric air gaps. In one embodiment, the machine includes a double-sided rotor with an inner rotor side and an outer rotor side; and a stator with an inner stator core and an outer stator core, wherein the double-sided rotor is concentrically disposed between the inner stator core and the outer stator core.

Abstract: A generator and/or electrical motor features elongated electromagnets which extend coaxially, not radially, about the axis of rotation of the axle, thus allowing multiple rings of magnets to be used. A chassis carries the electromagnets with the air gap surfaces of the electromagnets extending sideways, free of coils, into the air gaps with the plural rings of field magnets. Gearing arrangements may allow the ends of the can and the rings of field magnets mounted thereon to counter-rotate relative to one another. There may be four, eight or other numbers of rings of field magnets.

Abstract: Devices and methods are provided for a rotor assembly and an electric motor. One embodiment for a rotor assembly includes a first rotor including a first interface surface and a second rotor including a second interface surface corresponding to the first interface surface. Also, the first rotor is positioned with the first interface surface in direct physical contact with the second interface surface of the second rotor.

Abstract: An electromagnetic apparatus has a rotating element acting as a transfer bridge between two active energetic suppliers, the rotating element providing a ferromagnetic core with plural solenoid coils having induced electric energy from external permanent magnets; the core transferring energy by induction to the inner stator's wound active permanent magnet, the energy collector and inductor acting as a generator.

Abstract: An electric machine includes a plurality of magnets for generating a first magnetic field. A magnet holder retains the plurality of magnets. A first stator is disposed radially outward from the magnet holder for generating a second magnetic field. The first stator includes a plurality of stator poles separated by slots with each of the stator poles having a concentrated winding with a respective number of turns formed around each respective stator pole. A second stator is disposed radially inward from the magnet for generating a third magnetic field. The second stator has a plurality of stator poles separated by slots with each of the stator poles having a concentrated winding with a respective number of turns formed around each respective stator pole. The magnet holder and magnets retained therein are rotatable between the first stator and second stator.

Abstract: A magnetic force rotation device includes a rotor and a stator. The rotor is provided with a plurality of magnetic assemblies containing permanent magnet. The plurality of magnetic assemblies are arranged along the circumferential direction of the rotating shaft to form a wheel-shaped ring, and each magnetic assembly is provided with two magnetic poles. The stator is provided with a plurality of magnetically isolated electromagnets coaxially arranged. The electromagnets form a wheel-shaped ring around the rotating shaft, and each electromagnet is provided with paired poles. The wheel-shaped ring of the stator is at least party surrounded by the wheel-shaped ring of the rotor, so that each pole of the paired poles of the electromagnets of the stator corresponds to one magnetic pole of the two magnetic poles of the magnetic assemblies of the rotor respectively. Two axial component air gaps are provided between the rotor and the stator.

Abstract: Provided is a small motor superior in weight/torque balance. A phase stator 10 and B phase stator 12 are disposed to face each other. A rotor is interpositioned between these stators. Electromagnetic coils are provided to the stators evenly in the circumferential direction. A permanent magnet is provided to the rotor evenly in the circumferential direction. The exciting polarity of the electromagnetic coil is alternately opposite, and this is the same for the permanent magnet. A signal having a prescribed frequency is input to the A phase electromagnetic coil and B phase electromagnetic coil. The rotor rotates between the stators as a result thereof.

Abstract: The invention relates to a power storage system intended to transmit power to and from a driving system of a vehicle. A power storage having a stator provided with two windings and at least one rotor provided with a magnetic-flux generating device is comprised. The rotor is connected to a flywheel intended for storage of energy. The two windings of the stator are arranged for high and low voltage, respectively. The power storage is arranged to transmit power to and from the electric apparatus as well as store energy transmitted from the electric apparatus in the flywheel.

Abstract: An electromagnetic machine for extracting power from a turbine engine includes an outer rotor and an inner rotor rotatably supported adjacent to a stator. The stator is disposed between the inner and outer rotors. The stator has an inner set of windings disposed on an inner surface adjacent to the inner rotor, and an outer set of windings on an outer surface of the stator adjacent to the outer rotor. A plurality of permanent magnets are disposed on an inner surface of the outer rotor element and on an outer surface of the inner rotor element. Air gaps are defined between the outer surface of the stator and the outer permanent magnets, and between the inner surface of the stator portion and the inner permanent magnets. The inner stator windings form a set of multiple-phase windings, and the outer stator windings form a set of multiple-phase windings.

Abstract: A non-ventilated motor-generator includes a rotor supported for rotation on bearings inside a closed metal housing. The rotor is constructed of two spaced apart rotor sections having permanent magnets that drive magnetic flux across an air gap between the rotor sections. An air core armature in the air gap has windings in a non-magnetic structure that is structurally coupled to the housing. The armature is thinner than the armature air gap and is positioned such that there is a physical air gap on each side of the armature. The rotor has air flow passages through which air is induced to flow, in operation, in a polloidal loop that includes a portion that passes through the armature air gap, picking up heat from the armature, and a portion that is in contact with the inside of the motor-generator housing where the heat is transferred to the housing and dissipated to the atmosphere.

Abstract: The present invention provides cancellation of cogging torque of a permanent magnet electrical machine using two sets of magnetic elements, one set is mechanically coupled to the stator with the other set being mechanically coupled to the rotor of the machine. At least one of the two sets has permanent magnets with the magnetic elements of the other set being made of permanent magnets or non-magnetized ferromagnetic materials such as soft iron. When the arrangement of the elements of the two sets is properly designed, magnetic attraction and repulsion forces between the magnetic elements of the two sets produces, as the machine operates, an anti-cogging torque which substantially cancels the cogging torque of the machine.

Abstract: The invention relates to a synchronous electromechanical transformer that can be used as a multi-phase motor and generator, has a high specific torque, a small or negligible stop moment, a small moment irregularity, can be quietly operated, and has good heat permeability between the windings and the housing. It contains a rotor having uniformly distributed magnetic poles (4), and two stators (2) with concentrated windings (8) of at least two electrical phases. The individual stator contains the same number of similarly arranged electromagnetic poles (9) of each of at least two electrical phases arranged in related groups (7) of at least two electromagnetic poles of the same electric phase. The stator poles (9) can contain magnetically permeable polar cores and can be uniformly or non-uniformly distributed.

Abstract: A coreless and brushless direct-current motor includes an armature coil wound without core and formed in the shape of a saddle; an outside rotor magnet formed by a permanent magnet, the outside rotor magnet being provided at an outside of the armature coil in the shape of a cylinder so as to face the armature coil, the outside rotor magnet being rotated by the magnetic field; an inside rotor magnet formed by a permanent magnet, the inside rotor magnet being provided in the shape of a cylinder at an inside of the armature coil so that the inside rotor magnet has a pole opposite to the outside rotor magnet and a rotational shaft is independently provided; an output shaft connected to the inside rotor magnet; and a sealing part of a barrier structure which sealing part partitions the armature coil and the outside rotor magnet to an outside of the inside rotor magnet and seals the armature coil and the outside rotor magnet.

Abstract: A method and apparatus is disclosed for controlling a system comprising at least one electric motor. The system includes aspects which permit, among other things, electromagnetically disconnecting a failed permanent magnet motor from said system, weight savings in motor control electronics, controllability benefits and other benefits.

Abstract: An electrical machine includes a rotor with an inner rotor portion and an outer rotor portion, and a double-sided yokeless stator. The yokeless stator includes modular lamination stacks and is configured for radial magnetic flux flow. The double-sided yokeless stator is concentrically disposed between the inner rotor portion and the outer rotor portion of the electrical machine. Examples of particularly useful embodiments for the electrical machine include wind turbine generators, ship propulsion motors, switch reluctance machines and double-sided synchronous machines.

Abstract: Provided are a radial core type brushless direct-current (BLDC) motor and a method of making the same, having an excellent assembly capability of division type stator cores in a double rotor structure BLDC motor. The BLDC motor includes a rotational shaft, an integrated double rotor including an inner rotor and an outer rotor, and a rotor supporter wherein a trench type space is formed between the inner rotor and the outer rotor, and an end extended from the inner rotor is connected with the outer circumferential surface of a bushing combined with the rotational shaft, and an integrated stator wherein one end of the stator is disposed in the trench type space and an extension axially extended from the other end of the integrated stator is fixed to the housing of the apparatus.

Abstract: This electric motor is provided with an inner periphery side rotor, an outer periphery side rotor, and a rotating device that can change a relative phase between these rotors by rotating at least one of them about a rotational axis thereof. The rotating device is provided with a first member integrally and rotatably provided to the outer periphery side rotor, and a second member integrally fixed on an inside of the inner periphery side rotor which together with the first member defines a pressure chamber on the inside of the inner periphery side rotor. The rotating device changes a relative phase between the inner periphery side rotor and the outer periphery side rotor by supplying a hydraulic fluid to the pressure chamber. The rotating device is further provided with a linking passage that leaks the hydraulic fluid supplied to the pressure chamber to an outside of the pressure chamber.

Abstract: An electrical drive comprising stationary outer and inner stators; a rotatably mounted rotor with at least one pot-shaped element having a cylindrical wall and a base wall, wherein the cylindrical wall is thin-walled and made of magnetic material, wherein the base wall extends perpendicular and a cylindrical coaxial to a rotor shaft axis and the base wall is connected to the rotor shaft for transfer of torque; at least one electrical excitation coil; and a plurality of permanent magnet elements secured to the rotor for producing an excitation flux, wherein the magnet elements rest only against a radially inner side of the cylindrical wall and in the circumferential direction are disposed next to one another, wherein the magnet elements, together with the stators, form magnetic circuits that pass radially entirely through the cylindrical wall, and wherein the radial thickness of the magnet elements is greater than the thickness of the cylindrical wall.

Abstract: A permanent magnet electric generator includes a rotor assembly and a stator assembly. The rotor assembly has axially disposed annular outer and inner rings concentric with an axis of rotation. A plurality of magnets is disposed on the outer ring, each magnet having a north pole and a south pole. The permanent magnets are aligned with the axis of rotation, and adjacent magnets have alternating polarity. The stator assembly includes a plurality of stator blocks aligned to form an annular ring-shaped stator member retained by a stator frame. The stator member is configured to be at least partially disposed inside the rotor assembly and is circumferentially encircled by the rotor assembly.

Abstract: An electrical machine with torque limitation which is only slightly larger structurally than an identical machine without torque limitation and is thus as compact as possible has a stator with windings and a rotor supported movably relative to the stator, recesses distributed over the circumference and extending axially are present on the rotor surface, and a driver, located coaxially relative to the rotor and extending axially, is located in the air gap between the rotor and the stator, and exciter magnets on the upper driver face toward the stator and driver magnets on the inner driver face toward the rotor are located in such a way that upon rotation of the driver, the rotor is likewise capable of being set into rotation as a result of the rotary field generated by the windings and by the driver magnets.

Abstract: A radial core type double rotor brushless direct-current motor is provided in which a double rotor structure is employed with inner and outer rotors which are doubly disposed and thus a stator core is completely divided. The motor includes a rotational shaft which is rotatably mounted on a housing of an apparatus, cylindrical inner and outer yokes which are rotatably mounted on the center of the housing, inner and outer rotors including a number of magnets which are mounted with the opposing polarities on the outer surface of the inner yoke and the inner surface of the outer yoke, and a number of cores assemblies which are installed between the inner and outer rotors in which a number of coils are wound around a number of division type cores, respectively.

Abstract: A system for generating power comprising, a superconducting generator including, an armature assembly comprising, a body portion, a tooth portion having a front surface and a rear surface, a slot partially defined by the body portion and the tooth portion, an armature bar engaging the slot, and a cooling cavity partially defined by the tooth portion, communicative with the front surface and the rear surface.

Abstract: A stator coil assembly includes a cylindrical support tube with first and second pluralities of stator coils disposed radially around the support tube. Each stator coil includes first, second, third, and fourth linear segments, each having first and second planar broad sides. The second and fourth linear segments extend in parallel along a first axis with the first and second broad sides of the second and fourth linear segments lying in a common plane. The first and third linear segments extend in parallel along a second axis perpendicular to the first axis. Transition segments having first and second planar broad sides each join a pair of linear segments. The transition segments of the first and second pluralities of stator coils define curvatures toward and away from the center axis, respectively, such that the first and third linear segments are disposed at a substantially equal radial distance from the center axis.

Abstract: A permanent magnet electric generator includes a housing, and a stator and a rotor assembly disposed inside the housing. The rotor assembly has annular inner and outer rings concentric with the axis of rotation. A plurality of permanent magnets is distributed on the inner surface of the outer ring. The stator assembly includes a plurality of stator blocks configured to form an annular ring-shaped stator member. The stator member is concentric with the axis of rotation and is interposed between the inner and outer rings such that the outer ring circumferentially encircles the stator member. The stator member is wound with a three-phase winding for a three-phase voltage output.

Abstract: A hybrid induction motor includes a motor casing; a rotational shaft rotatably coupled with the motor casing; an induction rotor rotated by being integrally coupled with the rotational shaft and having a rotor core and a conductor bar inserted in the rotor core; a stator having a hollow into which the induction rotor is inserted and installed with a certain length in a direction of the rotational shaft; a first magnetic rotor inserted between the stator and the induction rotor and coupled with the rotational shaft so as to be freely rotatable; a second magnetic rotor inserted between the stator and the induction rotor so as to be symmetrical with the first magnetic rotor and coupled with the rotational shaft so as to be freely rotatable; and a magnetic spacer inserted between the first and second magnetic rotors.

Abstract: An electric motor comprising an inner periphery side rotor provided with inner peripheral permanent magnets with unlike poles, which are disposed alternately along a circumferential direction of the inner periphery side rotor, an outer periphery side rotor provided with outer peripheral permanent magnets with unlike poles, which are disposed alternately along a circumferential direction of the outer periphery side rotor, and a rotating device that varies a relative phase between the inner periphery side rotor and the outer periphery side rotor by rotating at least the inner periphery side rotor or the outer periphery side rotor around the rotational axis. The outer peripheral side rotor is arranged such that a rotational axis thereof is coaxial with a rotational axis of the inner periphery side rotor. The rotating device sets a variable width of the relative phase between the inner periphery side rotor and the outer periphery side rotor within a range of an electrical angle of below 180°.

Abstract: A rotor for a switched reluctance machine has its main magnetic circuit provided by two mouldings of soft magnetic composite. The mouldings are substantially identical and fit together to form a magnetic circuit which, by virtue of its design, has a very low inductance in the unaligned position. The portions of the magnetic circuit lie beyond the active length of the rotor poles and the flux path is described in three dimensions.

Abstract: A dual rotor-type motor includes a stator located between inner and outer rotors. The stator includes a core having first and second surfaces that face magnets on respective circumferential surfaces of the rotors. The surfaces of the core are spaced predetermined distances from the magnets on thr rotors and an insulating material can be included around the core.

Abstract: An axial-flux electric machine includes a stator and a rotor. The rotor may be rotatable about a rotor rotation axis, and at least a portion of the stator may face at least a portion of the rotor at an axial interface between the stator and the rotor. The rotor may include a rotor body and a permanent-magnet cluster that includes a plurality of permanent magnets mounted to the rotor body. The permanent-magnet cluster may cause magnetic flux to flow across the axial interface between the permanent-magnet cluster and the stator. The plurality of permanent magnets of the permanent-magnet cluster may include one or more permanent magnets forming a first axial permanent-magnet layer and one or more permanent magnets forming a second axial permanent-magnet layer disposed between the first axial permanent-magnet layer and the axial interface.

Abstract: A motor with three gaps produces higher torque than existing one or two gap motors. The motor uses both one radial and two axial gaps to produce torque. A single stator is provided with an essentially “U” shaped rotor shell having permanent magnets with back iron. The stator has loops of coil windings separated by pole pieces. Current flowing in three segments of the coils interacts with the fields from the permanent magnets to produce more torque. The plane of the coils extends through the centerline of the stator. In a given plane through the motor axis, the same polarity of the magnets on the rotor face the stator.

Abstract: The machine includes a rotor with an inner rotor core and an outer rotor core and a double-sided stator with an inner stator side and an outer stator side. The double-sided stator is concentrically disposed between the inner rotor core and the outer rotor core of the wind turbine generator. The double-sided stator is configured to enable at least a portion of magnetic flux to be shared between the inner stator side and the outer stator side. An example of a particularly useful embodiment for the machine includes a ship propulsion motor.

Abstract: An electromagnetic coupler for a motor vehicle. The coupler includes a first electric machine having an axis and including a first stator bearing a first coil, an input rotor and a first part of an output rotor, and a second electric machine including a second stator bearing a second coil and a second part of the output rotor. The input rotor includes an inner drum spaced apart from the first part of the output rotor and from the first yoke, while the second yoke is spaced apart from the second part of the output rotor by an air gap. The first coil is wound onto the yoke of the first stator around the axis of the first electric machine.

Abstract: A rotor 31 has permanent magnets 31a disposed on a surface of a disk-shaped back yoke 31b in such a manner that long sides of each permanent magnet extend in a radial direction and that a South pole and a North pole of the permanent magnet 31a are arranged in a circumferential direction. The four permanent magnets 31a are equally spaced from one another in the circumferential direction, and circumferentially-opposed magnetic poles of any two adjacent permanent magnets 31a are of the same magnetic polarity. Rotor cores 31c of a generally fan-shape are fixed to the back yoke to generally cover the four permanent magnets 31a. A flux barrier 31d for reducing the short-cutting of magnetic flux of the permanent magnet 31a is provided between any two adjacent rotor cores 31c, and is disposed at a radially-extending central portion of the permanent magnet 31a.

Abstract: A small power generating system includes a turbine driven by a fluid, a small high-speed rotation power generator including a permanent magnet rotor having a permanent magnet and rotated together with the turbine and a plurality of stator coils each of which is comprised of a coreless coil, the rotor being rotated such that voltage is induced on the stator coils, whereby power is generated by the power generator, and a back yoke disposed at one of two opposed sides of the stator coils which is opposed to the other side thereof further confronting the permanent magnet of the rotor, the back yoke being made of a magnetic material with a predetermined electrical resistance.

Abstract: A three-phase opposite rotating motor of a fan comprises a stator having a three-phase coil set without a core, a first rotor and a second rotor. The number of the poles of the first rotor is unequal to the number of the poles of the second rotor. The ratio of the number of solenoids of the three-phase coil set and the number of the first poles of the first rotor is 3:4, and the ratio of the number of solenoids of the three-phase coil set and the number of the second poles of the second rotor is 3:2, to ensure the motor works normally in an opposite rotating operation.

Abstract: A brushless motor-generator includes a rotor having a ferromagnetic tube with radially polarized, alternating polarity permanent magnet poles, and an air core armature that magnetically exerts torque upon the rotor. The magnetic poles drive magnetic flux across a radial magnetic air gap inside of the tube and through windings of the armature that are located in the air gap. The windings utilize wire that is comprised of multiple individually insulated strands that are bundled together and sheathed in an outer electrically insulating serve that separates adjacent windings and provides a higher dielectric breakdown strength than the insulation on the individually insulated strands.

Abstract: A method of producing a stator with a rotary current winding, having a first and second face end. On the face end, at least one shaped part with struts for winding guidance is provided. A brushless direct current machine with a stator, a shaped part for winding guidance for a stator with a rotary current winding, and a winding method for producing a stator with a rotary current winding are also disclosed.

Abstract: A hybrid induction motor comprises a stator fixedly installed in a casing, an induction rotor rotatably inserted into a center of the stator and having a shaft at a center thereof, a first synchronous rotor slid in a longitudinal direction of the shaft between the stator and the induction rotor and free-rotatably installed in a circumferential direction of the shaft, and a second synchronous rotor facing the first synchronous rotor, slid in a longitudinal direction of the shaft between the stator and the induction rotor, and free-rotatably installed in a circumferential direction of the shaft.

Abstract: A two-phase electric motor includes first and second coil groups and a magnet group. In the magnet group, N poles and S poles are disposed alternatively opposite the first and second coil groups. The first and second coil groups are disposed at positions that are out of phase with each other by an odd multiple of ?/2 in electrical angles. The coils of the first and second coil groups have substantially no magnetic material cores, and the electric motor has substantially no magnetic material yoke for forming a magnetic circuit.

Abstract: A temporary interconnection element to be installed between the rotor and the stator of a bearingless electric machine, for example during its transport, storage or assembly is described herein. The interconnection element is so designed that the rotor may be secured to an external assembly, such as for example the shaft of an internal combustion engine, before the element is removed from its interconnection position.

Abstract: An electric machine, such as a switched reluctance motor (SRM), having one or more transverse flux axes is described. The rotor and stator of the electric machine have more than one phase, not necessarily of even number. Flux guidance regions within the stator are angularly and spatially located such that they may be transverse, or not coinciding with, the plane perpendicular to the axis of shaft rotation. The flux guidance regions are composed so as to contain a magnetic field whose flux is guided in either a loop or coupled configuration. In the loop configuration, multiple flux guidance paths that are able to operate simultaneously exist within each chuck arrangement. In the coupled configuration, a single primary flux guidance path exists within the chuck arrangement. Transverse flux guidance allows for the removal and replacement of stator windings without significant disassembly or removal of the motor.

Abstract: A system for generating an electrical current in a circuit includes a rotor, a stator and a motor for rotating the rotor about a rotation axis. A plurality of permanent magnets are mounted on the rotor and radially distanced from the rotation axis. With this structure, the permanent magnets rotate with the rotor to establish a time-varying magnetic field. A winding is attached to the stator, connected to the circuit and immersed in the time-varying magnetic field generated by the permanent magnets. In one implementation, a switch is provided to reconfigure the circuit between a first, open-circuit configuration in which little or no current flows through the circuit, and a second closed-circuit configuration in which a current is generated at the winding for flow through the circuit.

Abstract: A radial core type double rotor brushless direct-current motor is provided in which a double rotor structure is employed with inner and outer rotors which are doubly disposed and thus a stator core is completely divided. The motor includes a rotational shaft which is rotatably mounted on a housing of an apparatus, cylindrical inner and outer yokes which are rotatably mounted on the center of the housing, inner and outer rotors including a number of magnets which are mounted with the opposing polarities on the outer surface of the inner yoke and the inner surface of the outer yoke, and a number of cores assemblies which are installed between the inner and outer rotors in which a number of coils are wound around a number of division type cores, respectively.

Abstract: A method and apparatus is disclosed for controlling a system comprising at least one electric motor. The system includes aspects which permit, among other things, electromagnetically disconnecting a failed permanent magnet motor from said system, weight savings in motor control electronics, controllability benefits and other benefits.

Abstract: A wind turbine generator includes a stator having a core and a plurality of stator windings circumferentially spaced about a generator longitudinal axis. A rotor is rotatable about the generator longitudinal axis, and the rotor includes a plurality of magnetic elements coupled to the rotor and cooperating with the stator windings. The magnetic elements are configured to generate a magnetic field and the stator windings are configured to interact with the magnetic field to generate a voltage in the stator windings. A heat pipe assembly thermally engaging one of the stator and the rotor to dissipate heat generated in the stator or rotor.

Abstract: A hybrid induction motor comprises a stator fixedly installed in a casing, an induction rotor rotatably inserted into a center of the stator and having a shaft at a center thereof, a first synchronous rotor installed between the stator and the induction rotor in a circumferential direction of the shaft so as to be freely rotatable, and a second synchronous rotor facing the first synchronous rotor in a longitudinal direction of the shaft and installed between the stator and the induction rotor so as to be freely rotatable.

Abstract: A switched reluctance machine is provided. The switched reluctance machine has a rotor including a rotor core, where the rotor core includes multiple laminated sheets, each of the laminated sheets including multiple ferromagnetic regions and multiple non-ferromagnetic regions formed of a single material. The ferromagnetic and the non-ferromagnetic regions are alternately arranged such that the ferromagnetic regions form multiple rotor teeth and the non-ferromagnetic regions define multiple non-ferromagnetic gaps between the rotor teeth.