Abstract: An electric motor includes a stator having multiple magnetic poles and a rotor rotatably mounted to the stator. The rotor includes a shaft, a commutator and a rotor core fixed to the shaft; and windings wound on the rotor core and electrically connected to the commutator. The rotor core is formed by stacking a plurality of laminations. Each lamination includes an inner ring having a hole for fixing the shaft; an outer ring radially spaced from the inner ring; multiple teeth extending outwardly from the outer ring, and multiple ribs connecting the inner ring to the outer ring. Each rib has a width w measured in a circumferential direction of the lamination. The number of ribs is n. The width w and the number n satisfy the formula: 0.75?n×w2?64, where the width w is measured in millimeters.

Abstract: A rotor includes: a plurality of first magnetic pole members that are disposed such that first end portions and second end portions are respectively coupled magnetically and mechanically to a first magnetic end plate and to a second magnetic end plate and so as to be separated from a magnetic intermediate plate magnetically; a plurality of second magnetic pole members that are disposed such that intermediate portions are coupled magnetically and mechanically to the magnetic intermediate plate and so as to be separated from each of the magnetic end plates magnetically; a plurality of permanent magnets that are disposed between the first and second magnetic pole members in a circumferential direction; and a nonmagnetic holding body for separating the first magnetic pole members magnetically from the magnetic intermediate plate, and for separating the second magnetic pole members magnetically from the magnetic end plates.

Abstract: The present invention relates to a flux-switching machine, including a stator having phase windings and field coils, wherein, in the machine, at least one field coil is arranged in a pair of notches separated by at least three teeth.

Abstract: A method for making a rotary electric machine comprises the steps of: preparing a core (18) having a plurality of pole expansions and a plurality of windings (100, 200, 300) made of electrically conductive material on the pole expansions, where at least a part of the windings (100, 200, 300) is made from a conductor wire having a free end (14) that can be connected electrically to a mains power supply; stably coupling to each other at least two free ends (14) of different windings (100, 200, 300) so as to connect them to a single power supply terminal; twisting the coupled ends (14) together to form a single electrical termination (5, 6, 7) twisted along a principal line of extension of the electrical termination (5, 6, 7).

Abstract: A method of forming a weld joint includes removing a portion of an insulator from a first core of a first magnet wire and a second core of a second magnet wire so that the first wire has a first heat affectable zone and a first insulator portion adjacent the first zone, and the second wire has a second heat affectable zone and a second insulator portion adjacent the second zone. The first and second insulator portions include the insulator disposed on the first and second cores, respectively. The first and second zones have a first and second distal end spaced apart from the first and second insulator portions, respectively. The method includes welding together only the first end and the second end to form the weld joint, wherein welding does not transfer heat to the first and second insulator portions sufficient to burn the insulator.

Abstract: A cryostat cartridge is disclosed. The cryostat cartridge may include a cryostat having a cryogen inlet, a cryogen outlet, and a superconductor material inside the cryostat configured to be cooled by a cryogen entering the cryostat through the cryogen inlet and exiting the cryostat through the cryogen outlet. The cryogen inlet is configured to be detachable from a cryogen source. The cryostat cartridge may be inserted into an activation module for activating the superconductor material and may also be inserted into a superconductor device.

Abstract: A plurality of salient poles projecting toward a stator are arranged on a rotor core along the circumferential direction while being spaced apart from each other, and rotor windings are wound around these salient poles. The rotor windings are short-circuited through diodes, respectively; and when currents rectified by the diodes flow through the rotor windings, the salient poles are magnetized to produce a magnet where the magnetic pole is fixed. The width ? of each salient pole in the circumferential direction is smaller than a width corresponding to an electric angle of 180° of the rotor, and the rotor windings are wound around each salient pole by short-pitch winding.

Abstract: A motor is provided. When m is half of a number of slots of one phase and n is a divisor of m, the overall parallel winding of a total number of parallels p is equally divided n-fold into partial parallel windings Ni, having a number of parallels p/n, each partial parallel winding Ni comprises m sub-coils, the m sub-coils including n types of m/n sub-coils having a number of turns tj, at least one of the sub-coils differing in number of turns from the other sub-coils, and, for each pair of the slots in the stator, one sub-coil of each partial parallel winding Ni is wound around the pair of slots, and n sub-coils wound around the pair of the slots include every one of the n types of the sub-coils of the numbers of tj.

Abstract: A coil forming apparatus for forming an electrical coil from an electrical wire. The apparatus includes a frame and a spindle assembly coupled to the frame. The spindle assembly includes: a first arm coupled to the frame, wherein the first arm includes a first moveable bracket and a plurality of first moveable spindles coupled to the first moveable bracket and to the electrical wire in a first position. The spindle assembly further includes a second arm coupled to the frame, wherein the second arm has a second moveable bracket that includes a plurality of second moveable spindles coupled to the second moveable bracket and coupled to the electrical wire in the first position. The coil forming apparatus includes a drive system coupled to the first moveable bracket and the second moveable bracket. The drive system is configured to move the first moveable bracket and the second moveable bracket.

Abstract: A method for making a rotary electric machine comprises the steps of: preparing a core (18) having a plurality of pole expansions and a plurality of windings (100, 200, 300) made of electrically conductive material on the pole expansions, where at least a part of the windings (100, 200, 300) is made from a conductor wire having a free end (14) that can be connected electrically to a mains power supply; stably coupling to each other at least two free ends (14) of different windings (100, 200, 300) so as to connect them to a single power supply terminal; twisting the coupled ends (14) together to form a single electrical termination (5, 6, 7) twisted along a principal line of extension of the electrical termination (5, 6, 7).

Abstract: An alternator comprising a rotor having plural magnetic poles in the circumferential direction; and a stator whose teeth are disposed opposite to the periphery of the rotor, with an air gap interposed between the rotor and the stator, wherein the coil conductors are wound on the stator so that two stator magnetic poles may be formed by two coil units of a phase wound around stator teeth within the range of 360 electrical degrees subtended by the magnetic poles of the rotor; each of the two coil units forming the stator magnetic poles spans an electrical angle less than 180 electrical degrees; the two coil turns forming the two stator magnetic poles are laid out so that they may not overlap each other; and the coil conductors are so wound that the adjacent stator magnetic poles exhibit opposite magnetic polarities.

Abstract: An axial rotary energy device including a segmented stator assembly having a plurality of segments arranged in an annular array. Each stator segment is constructed by stacking a plurality of PCB power conductor layers and a plurality of PCB series layers. Each layer having radial conductors extending from an inner via to an outer via. The vias electrically connect selected radial conductors of the series conductor layer and power conductor layer. Each power conductor layer includes a pair of positive and negative terminal vias for one phase of the electric current connected to selected outer vias. A daughter PCB layer electrically connects two adjacent segments together by having a first portion electrically connected to a negative terminal via located in one segment and a second portion electrically connected to a positive terminal via located in an adjacent segment together with a current conductor electrically connecting the two terminal vias together.

Abstract: A single stator electric machine includes a plurality of magnets for generating a first magnetic field. Each respective magnet represents a respective rotor pole. A magnet holder retains the plurality of magnets. A stator is disposed radially outward from the plurality of magnets for generating a second magnetic field. The 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. Each respective concentrated winding within the stator comprises non-overlapping phases which increase an active length of the windings of the stator and reduce an overhang of each respective winding with respect to each stator pole for improving torque efficiency. A number of rotor poles is at least eight and the number of rotor poles and a number of stator slots have a least common multiple of at least 36.

Abstract: A coreless electric machine includes: a permanent magnet on a first member; N-phase (N?2) air-core electromagnetic coils on a second member; and a coil back yoke on the second member, each electromagnetic coil including a conductor bundle in which a conductor is wound M times (M?2), coil sub-aggregates are provided, each including the N electromagnetic coils of the respective N phases and in each of which a conductor bundle forming an effective coil area of a first-phase electromagnetic coil contacts a second conductor bundle forming an effective coil area of another phase electromagnetic coil, and the second conductor bundle is in an air-core portion of the first phase electromagnetic coil, and the coil sub-aggregates are arranged along the cylindrical area, in which the coil sub-aggregates do not overlap in a radiation direction of the cylindrical area, and adjacent coil sub-aggregates contact each other.

Abstract: A device includes a rotor and a stator with coils arranged to form a phase element. The phase element includes a first coil group including a first coil and a second coil and a second coil group including a third coil and a fourth coil, where the rotor is positioned between the first coil group and the second coil group. The device also includes one or more switches that enable reconfiguration of the phase element by switching an electrical configuration of the coils. In a first mode, the coils are arranged with the first coil in a first coil path and the second coil in a second coil path that is coupled in parallel with the first coil path. The coils are arranged such that a voltage generated across the first coil path is substantially equal to a voltage generated across the second coil path.

Abstract: The invention is the compact multiphase wave winding of a high specific torque electric machine The invention is the compact multiphase wave winding (6) of the electric machine. Winding (6) is filling the slots (5) of the stator ferromagnetic core (3) and comprise one or multiple layers (40). Winding (6) fills the slots (5). Winding comprise N or a multiple on N conductors (8), where N represents the number of winding phases. Conductor (8) comprises or is assembled by parallel straight segments (10) and winding overhangs (11). Between the two straight segments (10) of one conductor (8) there are N teeth (4) and N?1 slots (5) or N+1 teeth (4) and N slots (5). Straight segments are connected by winding overhangs which shape in tangential axial plane differs for less than one sixth of magnetic period (7) from ellipse shape with one axis equal to half of magnetic period (7) and other axis length between half and three quarters of magnetic period (7) length.

Abstract: A stator phase circuit for an electric machine includes a phase winding circuit including a plurality of series coupled sub-winding circuits, each sub-winding circuit includes a respective sub-winding coupled in parallel across a respective first controllable switch.

Abstract: The Circular transformer-generator is a rotational electrical machine that joins creation of sinusoidal voltage and current with the transformation phenomenon or mutual inductivity of the individually wound stator coils. The Circular transformer-generator consists of the stator part that has a number of the inner pole extensions, and a number of the outer pole extensions with spaces between them for the individual stator windings, and of the double rotor assembly that contains the inner body and the outer body with the magnetic or electromagnetic poles that during rotor rotation supply induction to the stator assembly or the individual axially wound stator coils. The axially wound coils of the stator are connected to the Circular transformer-generator output, and at the same time are tied (act upon each other) by their mutual induction, during which time also the transformation coil ratio can be utilized.

Abstract: An electric wire includes a conductive portion 11 made of a material having a volume resistivity higher than that of copper, wherein the volume resistivity of the conductive portion is specified so that, in a frequency range in which the electric wire is used, a ratio of AC resistance of the conductive portion 11 to AC resistance of reference copper wire is less than 1.

Abstract: A transverse flux motor of an aspect of embodiments includes a rotor having an outer peripheral surface, an annular armature coil wound around a rotational axis of the rotor, a stator core including a pair of magnetic pole portions along an axial direction of the rotational axis, each magnetic pole portion facing the outer peripheral surface of the rotor across a gap and a supporting member containing the armature coil, and having a plurality of protruding portions protruding in the axial direction and provided around the rotational axis, wherein the adjacent two protruding portions around the rotational axis support at least part of the magnetic pole portions between the adjacent two protruding portions.

Abstract: An electric motor with an n-pole stator comprising a first stator winding and a second stator winding that can alternatively be supplied with current for the constitution of a pole-changeable electric motor. The supply winding is constituted by at least one turn of the first stator winding or of the second stator winding. Thus, a conventional winding design or coil design of the electric motor can be used to provide a supply voltage for electric equipment. The electric motor features an unchanged compact construction. Only at particular locations of existing stator turns current is tapped, such that a supply voltage of predetermined magnitude can be tapped based on the existing magnetic flux linkage during operation of the electric motor.

Abstract: A power system for a vehicle may comprise an electric machine attached to an engine of the vehicle. The electric machine may comprise only one stator core; a stator main winding wound on the one stator core; a stator exciter winding wound on the one stator core. The stator main winding and the stator exciter winding may be magnetically independent from one another even though magnetic-field-isolation material is not interposed between the stator main winding and the stator exciter winding.

Abstract: A stator phase circuit for an electric machine includes a phase winding circuit including a plurality of series coupled sub-winding circuits, each sub-winding circuit includes a respective sub-winding coupled in parallel across a respective first controllable switch.

Abstract: An electric rotating machine includes a multi-phase armature coil that is wound around a cylindrical armature core in a distributed winding manner. Each of phase windings of the armature coil is formed of an electric wire bundle which includes a plurality of insulation-coated electric wires that are electrically connected to one another. Each of the electric wire bundles forming the phase windings has a plurality of in-slot portions and a plurality of turn portions. Each of the in-slot portions is received in a corresponding slot of the armature core. Each of the turn portions protrudes from a corresponding axial end face of the armature core and extends to connect a corresponding adjacent pair of the in-slot portions of the electric wire bundle. For each of the electric wire bundles, the electric wires of the electric wire bundle are stranded at least at the turn portions of the electric wire bundle.

Abstract: A bar-wound stator, which is connectable to a plurality of fixed terminal points, includes a plurality of stator teeth and a plurality of magnet wires. Each of the plurality of magnet wires has a winding portion wound about at least one of the plurality of stator teeth and a junction portion extending away therefrom. A plurality of flexible leads each have a first portion ultrasonically welded directly to a respective one of the junction portions of the plurality of magnet wires. A second portion of each of the plurality of flexible leads extends flexibly away from the first portion and is configured for attachment to a respective one of the fixed terminal points.

Abstract: Provided are multiple switched reluctance motors and excitation control methods for same. Motors with various structures are provided having the same structural characteristics, a stator formed of an even number of salient pole pairs and a rotor formed of an even number of salient pole pairs. The salient poles of the stator salient pole pairs are arranged opposite the salient poles of the rotor salient pole pairs, with minimal air gaps left between said salient pole pairs, thus leaving the shortest magnetic return paths between the stator salient pole pairs and the rotor salient pole pairs arranged opposite one another, thus satisfying the minimum reluctance principle of the switched reluctance motor. In addition, due to the magnetic isolation between each stator salient pole pair, the performance of the magnetic pole of each stator salient pole pair is controlled by an excitation control power source and changed independently.

Abstract: A rotator coil is provided that includes a coil conductor and a mica tape wound a plurality of times around an outer periphery of the coil conductor. The mica tape includes mica paper and a reinforcing member, and has an adhesive resin layer containing an acryloyl-based component and a cyanate ester-based component between the mica paper and the reinforcing members. The reinforcing member, the mica paper, or both, are impregnated with a thermosetting resin composition, and hardened.

Abstract: A U phase winding, an X phase winding, a V phase winding, a Y phase winding, a W phase winding, and a Z phase winding are configured by mounting conductor wires so as to alternate repeatedly between 5?/6 short-pitch windings and 7?/6 long-pitch windings, and are mounted into the stator core in that order so as to be stacked sequentially in a radial direction so as to be offset by one slot each in a first circumferential direction.

Abstract: In a method for winding a core having an arch-like yoke portion, a tooth portion, and a tooth end portion by revolving a nozzle for feeding a conductive wire, when winding is performed in a bow-like area surrounded by an inner circumferential arc of the yoke portion and the chord thereof, upon winding on an end surface of the core, the nozzle moves so as to draw a convex-shaped trajectory proceeding from the tooth end portion side toward the yoke portion side with reference to the chord of the bow-like area, and upon winding on a side surface of the core, the nozzle returns from the yoke portion side to the tooth end portion side with reference to the chord of the bow-like area, and then moves along the side surface of the core.

Abstract: A stator includes a body portion having an outer portion and an inner portion that defines an interior region, a plurality of stator teeth members extending from the inner portion into the interior region, and at least one continuous conductor wound around select ones of the plurality of stator teeth members to form at least one pole. Each of the plurality of stator teeth members including a number of wraps of the at least one continuous conductor. The at least one continuous conductor including a number of twists that is fewer than the number of wraps.

Abstract: A controller for an axial gap-type motor (3) comprises a rotor (11) having a permanent magnet and a first stator (12a) and a second stator (12b) opposed to each other with the rotor (11) interposed therebetween in the axial direction of revolution of the rotor (11). The controller further includes an electrification control portion which supplies a torque current (Iq) for generating a magnetic field to revolve the rotor (11) to an armature winding (13a) of the first stator (12a) and supplies a field current (+Id) for reinforcing the magnetic flux by the permanent magnet of the rotor (11) or a field current (?Id) for weakening the magnetic flux to an armature winding (13b) of the second stator (12b). Consequently, the controllable range of the motor is increased and the axial gap-type motor can be operated at higher velocity and higher torque.

Abstract: Disclosed is a rotating electric machine for generating a constant frequency AC power supply from a variable speed primemover including: a stator wound with two sets of isolated polyphase windings having the same number of poles, with the polyphase windings located at about 90 degree displacement in space between them, and a rotor wound with two sets of isolated polyphase windings having the same number of poles and placed at about 90 degree displacement in space between them. The rotor has two winding terminals interconnected either internally or externally to the machine with mutually reverse phase sequence. When one set of stator winding is energized by an AC power supply of a given frequency and voltage, and the rotor shaft is rotated by an external means in the same direction as that of the rotating field of the stator.

Abstract: A stator for an axial-flux electric machine is provided with at least one flat winding formed thereon. The flat winding is circumferentially distributed over the flat stator. The flat winding comprises a plurality of petal-like sections which is substantially radial relative to an axis of the rotor.

Abstract: A system and method of manufacturing an electric machine comprising a rotor and a stator, wherein the stator comprises a fractional-slot concentrated winding having two sets of terminals, wherein a first set of terminals configures the fractional-slot concentrated winding to have a first pole-number (P1), and wherein a second set of terminals configures the fractional-slot concentrated winding to have a second pole number (P2) different from the first pole-number (P1).

Abstract: An example electric machine includes a stator disposed about an axis having a plurality of slots. The electric machine also includes a plurality of windings each having a first portion and a second portion. At least two of the plurality of windings are at least partially disposed within each of the plurality of slots. At least one of the first portion or second portion of at least one of the plurality of windings of each slot includes a first exposed end with a surface having a plurality of grooves, the surface in contact with a second exposed end of at least one other winding of the same slot. The first exposed end and second exposed end form a joint between the plurality of windings. A braze material is dispersed in a plurality of grooves disposed between the first exposed end and the second exposed end.

Abstract: An electric machine includes a core with a plurality of slots. A plurality of conductors are positioned in each of the plurality slots, with each slot including an equal number of conductors. At least one slot liner is also positioned in each of the plurality of slots. Each slot liner provides at least one slot liner channel in the associated slot, and each of the plurality of conductors extend through one of the slot liner channels. Differing numbers of slot liner channels are provided in the plurality of slots. Accordingly, all slots have the same number of conductors positioned therein, but all slots do not have the same number of slot liner channels.

Abstract: It is described a stator for an energy converting apparatus, the stator comprising the stator including a support structure having an annular shape around an axial direction; a first protrusion coupled to the support structure and extending radially from the support structure; a second protrusion coupled to the support structure and extending radially from the support structure, the second protrusion being spaced apart from the first protrusion in a circumferential direction; and a first wire arranged between the first protrusion and the second protrusion in a plurality of first radial layers located at different radial positions and configured such that a circumferential extent of a cross-sectional area of the first wire increases radially outwards. Further is described an energy converting apparatus including the stator, and a wind turbine including the energy converging apparatus.

Abstract: An electric motor includes a magnetic field induction device and an induced field device, rotating relative to one another, wherein the induction device comprises a set of two conducting coils around an axis, through which currents travel in the same direction, and a central part, placed between the two coils, comprising a superconducting element placed in a plane that is inclined relative to the axis of the coils, channeling the magnetic field produced by the coils on either side of the inclined plane.

Abstract: A synchronous motor which has reduced torque ripple while having a high torque includes a rotor and a stator, and U-phase coils, V-phase coils, and W phase coils are wound around sections of the yoke each located between two adjacent stator teeth. The number of turns in each coil and the direction in which each coil is wound are set to compensate for a difference between a timing at which a magnetic field produced at each stator tooth is at a maximum value and a timing at which a point between magnetic poles passes by the stator tooth as the rotor rotates, the difference in timing being caused by a difference between the interval between the magnetic poles and the interval between the stator teeth.

Abstract: A rotating machine includes a stator and a rotor configured to rotate within the stator. Rotor windings are supported in the rotor and are formed of a laminated electrical conductor in a single-layer saddle coil configuration. The conductor includes a first support lamina, a second support lamina, an insert including a high temperature superconductor disposed between the first and second support lamina, and a filler material surrounding the insert that bonds the insert to each of the first and second support lamina. At the location between the first support lamina and second support lamina corresponding to the location of the insert, the width dimension of the filler material on each side of the insert is at least 10 percent of a width of the conductor. The conductor is configured to carry at least 600 Amperes per turn and have a C-axis tensile strength of at least 21 MPa.

Abstract: A synchronous generator 1 including a rotor having a field winding placed in the slots thereof and a stator having an armature winding placed in the slots thereof, wherein the value of the number of slots per two poles in stator minus the number of slots per two poles in rotor is equal to or greater than +9, or equal to or smaller than ?9.

Abstract: A stator connector has an annular carrier structure adapted to be superposed on and fixed to the central annular portion of the stator and manufactured from an electrically insulating plastic overmolded onto a group of N conducting members which are separated from each other and electrically insulated by said plastic and having a generally arcuate shape. The conducting members have respective first projections extending out of the annular carrier structure. These first projections are adapted to be connected, in particular by soldering or welding, to terminals or ends of coils of the stator. Each conducting member further has at least one additional connection projection extending out of the annular carrier structure to form phase terminals for the stator.

Abstract: An electrical machine comprising a stator (1) and a rotor (2) movable relative to the stator is provided. The stator (1) comprises a doubled number of notches (3) with respect to a pole pair number p of the rotor. This is combined with differing numbers (n1, n2) of turns per phase winding or with differing tooth widths (Z1, Z2) of teeth (6, 7) of the stator which are formed between neighboring notches (3).

Abstract: An electric wire includes a conductive portion 11 made of a material having a volume resistivity higher than that of copper, wherein the volume resistivity of the conductive portion is specified so that, in a frequency range in which the electric wire is used, a ratio of AC resistance of the conductive portion 11 to AC resistance of reference copper wire is less than 1.

Abstract: A light deflection apparatus, including a stator section including a radial bearing having a first dynamic pressure generating groove, a thrust bearing having a second dynamic pressure generating groove, and a stator coil; and, a rotor section including a polygon minor, a magnet facing the stator coil, and a rotating body having a dynamic pressure surface facing the radial bearing and a dynamic pressure surface facing the thrust bearing, the rotor supporting the polygon minor and the magnet; wherein one end portion of the dynamic pressure bearing section included of the thrust bearing, the radial bearing and of the rotating body in the thrust direction is closed excluding a gap between the dynamic pressure bearing section of the radial bearing and the dynamic pressure bearing section of the rotating body.

Abstract: A synchronous electric motor includes rotor having a plurality of radially-oriented magnetic dipoles and a stator. Stator teeth group with a plurality of sets of stator teeth are arranged in the same position in terms of an electrical angle with another stator teeth group to provide rotational symmetry about an axis of the rotor. In each of the stator teeth groups a predetermined number of stator teeth are arranged at intervals different from intervals of the rotor magnetic dipoles. A main coil is wound about a predetermined number of stator teeth with a sub-coil further wound around one or more a teeth. Phase and magnitude of a resulting magnetic field is adjusted by the number of loops of the main coil and sub-coil. A given stator tooth can produce maximum torque despite any difference between an alignment of the stator tooth and an inter-polar interval of the stator.

Abstract: The invention relates to a stator for an electric machine, comprising at least two sub-stators having respective grooves for receiving windings. The groove openings of the two sub-stators are displaced in relation to each other in the circumferential direction. The invention further relates to an electric machine comprising the stator. The two sub-stators are combined with each other axially and/or in the circumferential direction.

Abstract: A segmented annular stator for a dynamo-electric machine is disclosed which simplifies transport and assembly of the machine. The segment has a cross section essentially shaped as a circular arc and includes a first and a second segment boundary configured for attachment to an additional segment, a corresponding coil associated with each phase of a three-phase system, a first conductor, and a second conductor. The first conductor is connected to the second conductor via an end connection in an area of end windings, such that a first coil associated with a first phase surrounds second and third coils associated with second and third phases of the three-phase system.

Abstract: A terminal module includes a ring-shaped rail having a groove extending in a circumferential direction, a bus bar fitted into the groove, and a connector portion having a connector terminal connecting the bus bar with an external wire. The rail has a phase determining hole for determining a phase of rotation of the rail about an axial direction.

Abstract: In an electric rotating machine, a stator coil is comprised of first and second winding groups. The stator coil is wound around a stator core in a concentrated winding manner so that the phase difference in electrical angle between each corresponding pair of windings of the first and second winding groups is equal to ?/6. Further, the windings of the first and second winding groups are connected to form ?-Y connections. Consequently, the sixth harmonic components of the electromagnetic forces created by the windings of the first winding group can be offset by those of the electromagnetic forces created the windings of the second winding group. As a result, the total magnetic noise and torque ripple generated in the machine can be reduced. Moreover, the machine can be driven with only a single three-phase inverter to achieve the effects of reducing the total magnetic noise and torque ripple.