Abstract: A motor, a compressor and a refrigeration device are provided. The motor includes a stator and a rotor. The stator has a central hole and multiple stator slots arranged in an annular array centered on an axis of the central hole. The rotor is provided in the central hole. Multiple rotor slots are provided on the rotor, and are arranged in an annular array centered on the axis of the central hole and close to an edge of the rotor. A plane perpendicular to the axis of the central hole is a reference plane, a sum of projected areas of the stator slots on the reference plane is S1, a sum of projected areas of the rotor slots on the reference plane is S2, an outer periphery of the stator projected on the reference plane forms a projected pattern, and an area of the projected pattern is S3.

Abstract: A refurbished rotor of a wound rotor machine. The refurbished rotor includes a plurality of windings assembled to the rotor core, each manufactured from two separate bars: a top coil and a bottom coil. The top coil is positioned in a rotor core slot at a position radially outward of a position of the bottom coil within another rotor core slot. Each top coil and each bottom coil has a flat rectangular cross-section. On a connection end of the rotor where rotor leads are attached, the top coil has a flat end positioned alongside and in alignment with a flat end of the bottom coil of an adjacent one of the plurality of windings. The top coil and the bottom coil have respective flat ends joined to each other on a non-connection end of the rotor opposite the connection end by a joint for establishing electrical continuity.

Abstract: A rotary electric machine member manufacturing method includes: a step of providing a motor core by stacking a plurality of electromagnetic steel sheets; and a step of welding the motor core by keyhole welding while pressurizing the motor core in a stacking direction with a welding pressure lower than that at which the thickness of the motor core in the stacking direction levels off. The thickness is a length of the motor core between a first end of the motor core and a second end of the motor core.

Abstract: A rotor of a rotary electric machine includes a first magnet and a fourth magnet whose magnetic fields are oriented in radial directions of a stator, and a second magnet and a third magnet whose magnetic fields are oriented in circumferential directions of the stator. Teeth portions of the stator each include a base portion that protrudes in a radially inward direction of a yoke portion, a flange portion that is wider than the base portion, and an expanding portion interposed between the base portion and the flange portion. An angle of intersection between the base portion and the expanding portion is 108° to 130°. A distance (thickness) from an inner circumferential side end part to an outer circumferential side end part of the flange portion is 0.2 mm to 2.0 mm.

Abstract: A synchronous electrical motor, which may operate poly-phase electrical power, is configured to operate at a rated flux configuration and a high flux configuration. To enable the high flux configuration, some coils wound about the stator of the electric motor can be designated bypass coils and can be selectively disconnected from the power source supplying the motor with electrical power. The remaining permanent coils continue to receive full line power and generate a rotating magnetic field with an increased magnetic flux. At startup from standstill conditions, the bypass coils are selectively disconnected so that a flux boost occurs and a corresponding increase in output torque of the electric motor.

Abstract: An electric machine operable as a motor or generator includes a stator having a body portion substantially in the shape of a hollow column with an outer wall and an inner wall. The body portion has a plurality of first slots and a plurality of second slots each running through the body portion in a longitudinal direction. The plurality of first slots are distributed in a circumferential direction between the outer wall and the inner wall, and the first slots are circumferentially closed slots. The plurality of second slots are distributed in the circumferential direction between the first slots and the inner wall, and the second slots are circumferentially closed slots and are spaced apart from the first slots.

Abstract: A rotor stack assembly includes multiple plates each including multiple elongated slots each oriented radially outward from a longitudinal central axis of each plate toward an outer perimeter wall of the plate. Multiple openings are each positioned proximate to one of the slots and directed outwardly through the outer perimeter wall. Multiple runners individually extend through the plate and individually open into one of opposed ends of each of the slots. Multiple bars of a conductive material are each extended through aligned ones of the slots of each of the multiple plates.

Abstract: A rotor for an interior permanent magnet machine (IPM), comprising a rotor core having a plurality of magnetically conductive laminations stacked in a rotor axial direction. The magnetically conductive laminations comprise cut-out portions forming a plurality of flux barriers (FB) radially alternated by flux paths (FP), at least a first part of the flux barriers (FB) housing permanent magnets, at least a second part of the flux barriers (FB) being filled with an electrically conductive and magnetically non-conductive material creating a cage inside the rotor core. The rotor further includes a first and a second short circuit ring positioned at the opposite ends of the rotor core, the first short circuit ring being different from the second short circuit ring.

Abstract: Core slots are provided in an outer circumferential side of a rotor core and extend in an axial direction of a rotor shaft. A rotor conductor is a rod-shaped conductor inserted in each of the slots, and after insertion of the rotor conductor in each slot, a flared portion is formed flaring in a slot-transverse direction, and a propping-apart force occurring between the flared portion and both side wall surfaces of the slot fixes the rotor conductor to the slot. In an inner wall of an outer circumferential side of each slot abutting the flared portion, an unevenness is arranged along the axial direction of the rotor shaft.

Abstract: A winding system for a stator and/or a rotor of an electric machine is disclosed. The winding system comprises several conductor sections, two annular conductors (+, ?) on a first side of the winding system, to which the conductor sections are coupled by means of half bridges, and at least one half bridge on an opposite side of the winding system, to which at least one conductor section is connected.

Abstract: A cage rotor for an electrical machine includes a rotor laminated core having a groove, and a short-circuiting ring having a first material and cast onto an axial end of the rotor laminated core. Arranged in the groove is a bar which has a bar end. The bar end penetrates into the first material of the short-circuiting ring and has a plurality of notches to provide the bar end with a greater flexibility.

Abstract: This squirrel-cage motor rotor includes a plurality of conductor bars provided at regular intervals along the circumferential direction of a rotor core, short-circuit rings connected to ends of the conductor bars, and reinforcement covers having axial-direction surfaces being in contact with axial-direction-end surfaces of the short-circuit rings. The reinforcement covers are enclosed by casting in the short-circuit rings. Holding rings are attached to the outer circumferential surfaces of the flange portions of the reinforcement covers and the outer circumferential surfaces of the short-circuit rings by interference fit.

Abstract: The invention relates to a method for balancing a component (1), in particular a rotor of an electric machine, using pins (11, 11?) which are introduced into prefabricated openings (5, 7, 9) in the component (1). The component (1) is balanced in that pins (11, 11?) of different lengths, cross-sectional areas, and cross-sectional shapes are fixed in corresponding openings (7, 9) in the component (1). Furthermore, the pins (11, 11?) can be assembled from multiple elements (13, 13?), and the method can be used to increase the balancing quality incrementally in one or more stages. The imbalance of the component (1) can be considerably reduced using said method, and simultaneously the weight, space requirements, and inertia of the component (1) can be reduced. In addition, the method can be automated.

Abstract: A number of variations may include at least one mold portion that may define a first cavity, a circular gating system, and at least one sprue. The circular gating system may surround the first cavity and define a continuous in-gate from the circular gating to the first cavity. The at least one sprue and at least one vent may be in fluid communication with the circular gating system and the first cavity.

Abstract: A rotor of an electric machine is provided and includes first and second core elements formed to define annular arrays of axial slots and rotor bar openings, each axial slot being fluidly communicative with a corresponding one of the rotor bar openings and a spacer element interposed between the first and second core elements to define a rotor vent opening fluidly communicative with the axial slots.

Abstract: A method for fabricating a rotor assembly includes assembling shorting end rings onto conductor bars through a steel laminate stack. The ends of the steel laminate stack are immersed into a bath containing molten metal.

Abstract: A squirrel-cage rotor includes a rotor core having in its circumferential direction a plurality of slots extending in an axial direction, a plurality of conductor bars stored in each slot of the rotor core and whose ends are projected from an axial direction end surface of the rotor core, and a pair of end rings arranged at the ends of the rotor core and each having a plurality of fitting portions into which the both ends of the conductor bars projecting from the axial direction end surface of the rotor core are fitted. In the conductor bar, among the cross-sectional shape in a plane perpendicular to the axial direction, the shape on the rotor central axis side is a circular arc shape. In the plane perpendicular to the axial direction, a gap is provided on the rotor central axis side of the fitting portion fitted with the conductor bar.

Abstract: The invention relates to a cage rotor for an asynchronous machine (1) comprising starting bars for improving the starting behavior. The invention further relates to a method for producing such a cage rotor. In order to achieve as great an efficiency as possible, the cage rotor comprises a laminated rotor core (2) having grooves (3) and operating bars (5; 6; 7; 8; 15) disposed in the grooves (3) and contacting the laminated rotor core (2) directly on the inner groove base as seen in the radial direction of the cage rotor, wherein the operating bars (5; 6; 7; 8; 15) comprise partial cladding (9; 10; 11) enclosing an outer surface of the operating bars (5; 6; 7; 8; 15) as seen in the radial direction (12) of the cage rotor, wherein the material of the operating bars (5; 6; 7; 8; 15) comprises a greater specific conductivity than the material of the partial cladding (9; 10; 11).

Abstract: A squirrel-cage rotor of an asynchronous machine, in particular a die-cast rotor, includes a rotatable shaft, a laminated core being rotation-locked on the shaft and having grooves and opposing end faces. A squirrel-cage winding has rotor rods disposed in the grooves and a cage ring disposed on each of the end faces and electrically connecting the rotor rods. A pair of retaining elements is disposed on the shaft, wherein each retaining element extends in a radial direction in form of a disk or a spoke and has in an axial direction a wall and/or an axially extending finger. The wall overlaps on a radial periphery in the axial direction both the cage ring and a predefined axial section of the rotor rods that terminate in the cage ring, without increasing an external diameter of the laminated core.

Abstract: The invention relates to a squirrel-cage rotor for an asynchronous machine. In order to increase the electrical efficiency for a cage rotor composed of two materials, the cage rotor comprises a rotor core (1) having grooves (3), end rings (5) of a first material that are cast onto the rotor core on the end face, and conductors (4) that are arranged in the grooves and that are made of a second material that has an electric conductivity that is higher than the electric conductivity of the first material, wherein the conductors (4) comprise a coating (8) made of a coating material on the surface of the conductors, wherein the coating adjoins the second material of the conductors (4) by means of a first alloy layer (2) made of the second material and the coating material and adjoins the cast first material by means of a second alloy layer (9); made of the first material and the coating material.

Abstract: An end ring assembly for a rotor, wherein the rotor is rotatable about a central longitudinal axis, includes a plurality of annular sheets stacked adjacent one another. Each of the plurality of annular sheets has a first surface and a second surface spaced opposite the first surface. The end ring assembly also includes a braze material sandwiched between and joining only a first portion of the first surface of each of the plurality of annular sheets, and a corresponding second portion of the second surface of a respective adjacent one of the plurality of annular sheets without joining an entirety of the first surface of each of the plurality of annular sheets and the second surface of the respective adjacent one of the plurality of annular sheets. A method of forming the end ring assembly is also disclosed.

Abstract: A rotor assembly for an electric device includes a laminated stack of electric steel sheets defining a plurality of longitudinally extending grooves. A conductor bar is disposed within each of the grooves. Each of the conductor bars includes a first end and a second end extending longitudinal outward from opposing axial end surfaces of the laminated stack. The first end and the second end of the conductor bars include a textured surface having micro-sized surface irregularities. A first end ring is cast in place over the first ends of the conductor bars, and a second end ring is cast in place over the second ends of the conductor bars. The textured surface in the first ends and the second ends of the conductor bars mechanically interlocking with the cast in place first end ring and second end ring respectively.

Abstract: A rotor core for an induction motor. The rotor core includes a body that at least (i) extends axially from an outer surface of the body inward toward a central axis, (ii) extends from a first axial end to a second axial end, and (iii) defines a plurality of internal grooves. Further, each groove at least (iv) includes an opening at the outer surface of the body, (v) is defined by two opposing walls, (vi) extends from the first axial end to the second axial end, (vii) extends axially between the opening at the exterior surface and an inward end, and (viii) includes a body section. And wherein (ix) at least one wall of the opposing walls of the groove includes, in the body section of the groove, an extended segment forming a portion of increased breadth for the groove.

Abstract: To provide an indication motor rotor capable of improving motor performance by concentrating portions under magnetic saturation conditions of rotor teeth. The rotor 1 of an induction motor of this invention may include slots 3 formed approximately in the shape of a T. The slots 3 may be formed so that top slots 3a are arranged on an outer peripheral portion of a rotor core 1a, and bottom slots 3b are arranged on an inner side of the top slots 3a. The width in the circumferential direction of the top slot 3a is wider than the width in the circumferential direction of the bottom slot 3b, and the width in the circumferential direction of a rotor tooth 4 between adjacent top slots 3a is narrower than the width in the circumferential direction of the rotor tooth 4 between adjacent bottom slots 3b.

Abstract: A rotor for a high power electric motor intended to operate at particularly high rotational speeds. It includes a magnetic mass, gripped on either side by short circuit rings, and passed through at a plurality of notches by main bars forming a squirrel cage. The rotor also includes secondary bars passing through the magnetic mass via notches. The shape and arrangement of each notch is defined so as to ensure contact between the main bars and the secondary bars sufficient to allow the passage of an electric current when the rotor is in rotation. In particular, the invention applies to asynchronous motors capable of operating at high peripheral speeds typically starting at 100 m·s?1, in particular motors intended for gas or oil applications, whether land-, sea-, or undersea-based.

Abstract: To provide an indication motor rotor capable of improving motor performance by concentrating portions under magnetic saturation conditions of rotor teeth. The rotor of an induction motor of this invention may include slots formed approximately in the shape of a T. The slots may be formed so that top slots are arranged on an outer peripheral portion of a rotor core, and bottom slots are arranged on an inner side of the top slots. The width in the circumferential direction of the top slot is wider than the width in the circumferential direction of the bottom slot, and the width in the circumferential direction of a rotor tooth between adjacent top slots is narrower than the width in the circumferential direction of the rotor tooth between adjacent bottom slots.

Abstract: A motor rotor has an outer casing, multiple silicon-steel sheets, multiple copper sheets and multiple copper bars. The silicon-steel sheets are stacked and mounted in the outer casing and each has multiple through holes formed through the silicon-steel sheet at intervals. The copper sheets are mounted in the through holes, extend out of the silicon-steel sheets and each has two side faces. Each side face of the copper sheet has a flat inner end and an outer end. The flat inner end of the side face of the copper sheet is flat to enable a distance between the outer ends of two adjacent copper sheets to be smaller than a distance between the flat inner ends of the adjacent copper sheets. The copper bars are inserted into the copper sheets from the flat inner ends to the outer ends of the side faces of the copper sheets.

Abstract: The present invention is directed to provide an induction motor having an ideal efficiency at the normal operation time, while obtaining a high locked-rotor torque without having to use a special drive circuit. According to the induction motor related to the present invention, the induction motor has a rotor 11 having a double squirrel-cage secondary conductor, wherein the rotors 11 includes a rotor core 11a formed by laminating a plurality of electromagnetic steel plates, outer layer slots 40a filled with conductive material, installed along an outer peripheral edge of the rotor core 11a, inner layer slots 40b filled with conductive material, disposed inside of the outer layer slot 40a in the radial direction, and inner peripheral thin bridges 82 made of electromagnetic steel plate, installed in between the outer layer slots 40a and the inner layer slots 40b.

Abstract: An electrical power generation apparatus is embedded in a contra-rotating propulsion system that includes overlapping first and second shafts operatively connected for counter-rotation about a common axis. The electrical power generation apparatus includes a winding mounted to one of the shafts and a field array mounted to the other of the shafts adjacent to the winding. Relative rotation of the winding and the field array induces electrical current in the winding.

Abstract: To provide an indication motor rotor capable of improving motor performance by concentrating portions under magnetic saturation conditions of rotor teeth. The rotor 1 of an induction motor of this invention may include slots 3 formed approximately in the shape of a T. The slots 3 may be formed so that top slots 3a are arranged on an outer peripheral portion of a rotor core 1a, and bottom slots 3b are arranged on an inner side of the top slots 3a. The width in the circumferential direction of the top slot 3a is wider than the width in the circumferential direction of the bottom slot 3b, and the width in the circumferential direction of a rotor tooth 4 between adjacent top slots 3a is narrower than the width in the circumferential direction of the rotor tooth 4 between adjacent bottom slots 3b.

Abstract: It is an object to obtain a highly efficient induction motor which does not degrade the fitting strength of shrink-fit and of which the starting torque is high, and further to obtain a highly reliable hermetic compressor which suppresses the oil amount flowing out of the hermetic compressor.

Abstract: A motor apparatus has a housing, an outer stator positioned within the housing, an inner stator positioned within the housing and interior of the outer stator, a rotor positioned in the housing between the outer stator and the inner stator, a first squirrel cage affixed to an outer diameter of the rotor in spaced relationship to the outer stator, a second squirrel cage affixed to an inner diameter of the rotor in spaced relationship to the inner stator, and a shaft connected to the rotor such that the shaft rotates relative to a rotation of the inner rotor. The shaft extends outwardly of the housing. A power source is electrically connected to the outer stator and to the inner stator.

Abstract: To provide an indication motor rotor capable of improving motor performance by concentrating portions under magnetic saturation conditions of rotor teeth. The rotor 1 of an induction motor of this invention may include slots 3 formed approximately in the shape of a T. The slots 3 may be formed so that top slots 3a are arranged on an outer peripheral portion of a rotor core 1a, and bottom slots 3b are arranged on an inner side of the top slots 3a. The width in the circumferential direction of the top slot 3a is wider than the width in the circumferential direction of the bottom slot 3b, and the width in the circumferential direction of a rotor tooth 4 between adjacent top slots 3a is narrower than the width in the circumferential direction of the rotor tooth 4 between adjacent bottom slots 3b.

Abstract: The present invention is directed to provide an induction motor having an ideal efficiency at the normal operation time, while obtaining a high locked-rotor torque without having to use a special drive circuit. According to the induction motor related to the present invention, the induction motor has a rotor 11 having a double squirrel-cage secondary conductor, wherein the rotors 11 includes a rotor core 11a formed by laminating a plurality of electromagnetic steel plates, outer layer slots 40a filled with conductive material, installed along an outer peripheral edge of the rotor core 11a, inner layer slots 40b filled with conductive material, disposed inside of the outer layer slot 40a in the radial direction, and inner peripheral thin bridges 82 made of electromagnetic steel plate, installed in between the outer layer slots 40a and the inner layer slots 40b.

Abstract: The invention provides a rotor for an electrical motor. The rotor comprises both a squirrel cage and a number of magnets and can be inserted e.g. in a line-start motor. To secure the magnets in cavities in a core of the rotor, an end plate is attached to one axial end face by rivet means, and to simplify manufacturing of the rotor, the rivet means forms part of at least one of the short circuit rings of the squirrel cage.

Abstract: A single-phase induction motor comprises a stator having a stator coil; an induction cage rotor rotatably inserted into a receiving groove of the stator, having a rotation shaft at a center thereof, having a plurality of first conductor bars at an outer peripheral portion thereof with the same interval in a circumferential direction, having a protrusion portion at an outer circumferential surface thereof, and having a plurality of second conductor bars installed at the protrusion portion in a circumferential direction; and a permanent magnet rotor free-rotatably installed between the stator and the induction cage rotor.

Abstract: A synchronous inductance motor provided in a rotor includes at least a pair of slit portions forming a two-pole magnetic polar projection having an easy-to-pass direction of the magnetic flux, i.e., q-axis and a difficult-to-pass direction of the magnetic flux, i.e, d-axis which are almost orthogonal and a plurality of slot portions close to an outer circumference in the slit portions and connected to at least an end of the slit portion in a direction of the d-axis for generating inductance torque. Further, conductivity material is filled in the slit portions and the slot portions.

Abstract: An armature for an actuator for applying vibration to a body along an axis, the armature having at least two parallel wound helical windings on the axis, and a terminal arrangement connected to the ends of the windings for selective connection of the windings to two external A.C. drivelines, the terminal arrangement being switchable between a relatively low impedance mode, with at least two of the windings connected electrically in parallel, and a relatively high impedance mode, with two of the windings or two groups of parallel-connected windings connected in series.

Abstract: A method of making a squirrel cage rotor of copper material for use in AC or DC motors, includes forming a core with longitudinal slots, inserting bars of conductive material in the slots, with ends extending out of opposite ends of the core, and joining the end rings to the bars, wherein the conductive material of either the end rings or the bars is copper. Various methods of joining the end rings to the bars are disclosed including electrofriction welding, current pulse welding and brazing, transient liquid phase joining and casting. Pressure is also applied to the end rings to improve contact and reduce areas of small or uneven contact between the bar ends and the end rings. Rotors made with such methods are also disclosed.

Abstract: A variable-speed electromechanical energy converter includes a wound-type induction motor and a power rectifier connected to a secondary winding of the motor to convert AC power produced by the motor into DC power. A chopper is connected to an output of the power converter to control the output thereof according to a control signal and a capacitor is connected through a rectifier device to the chopper. A power inverter converts DC power stored in the capacitor into AC power which is fed back to an AC system connected to the motor. The motor includes a cage rotor disposed between a wound rotor and a rotor shaft, the cage rotor being separated from the rotor shaft by an inner gap and separated from the wound rotor by a middle gap so as to rotate independently of the rotor shaft.

Abstract: The invention relates to a fuel delivery unit, having a side channel pump that in a housing (13) has a pump chamber (14) and in the pump chamber (14) has an impeller (16), and having an electric motor (12) that drives the impeller (16) and has a stator and a rotor (29). The impeller (16) of the fuel delivery unit is the rotor (29) of an asynchronous motor. The electric motor (12) can be assembled from only a few, highly reliable and strong components.

Abstract: A brushless doubly-fed induction machine comprising dual cage rotors, suitable for use in generator applications requiring a fixed-frequency electrical output that is independent of a rotational speed at which the machine is driven or motor applications requiring limited variable speed operation when connected to an AC mains. Various embodiments are disclosed, but each includes a stator frame in which first and second annular stators are mounted spaced-apart, end-to-end along a common axis. Each annular stator includes a core wound with polyphase distributed windings defining a plurality of poles. First and second rotors, mounted on a common shaft, are disposed within the first and second annular stators, respectively. Each of the rotors includes a laminated core having a plurality of longitudinally-extending slots defined around a periphery thereof, and at least one conductor is disposed in each slot.

Abstract: An AC squirrel cage motor runs with a rotor current frequency equal to the slip of the motor times its excitation frequency. It is desirable to reduce the rotor current on start up by means of an increased resistance, and then to run the motor with a reduced resistance once it is started. This invention takes advantage of the skin effect of high frequency currents by increasing rotor end ring resistance during startup. After the motor has started up, and has reached full speed, the rotor frequency is reduced to merely the slip multiplied by the stator frequency. The skin effect on the rotor current is less, and the motor runs with reduced resistance.

Abstract: An electric motor comprising two separate and coaxially spaced armatures as well as a magnet-equipped rotor arranged between the two armatures. One armature is fixed to a motor housing being a static armature, while the other armature is free to rotate, having the motor output shaft as a central and integral part thereof. The rotor operates as a rotor for both armatures having magnet pole pairs on both sides for interaction with each respective armature. Thus, the motor comprises two part-motors having a common rotor.

Abstract: An electric motor for an x-ray tube of a medical imaging system is described herein. The electric motor includes a stator and a substantially cylindrical rotor. The stator includes stator winding slots and stator windings injected into the stator winding slots. The stator also has a stator bore. The rotor is rotatably mounted within a stator bore so that the rotor is coaxial with the stator bore. The rotor includes a rotor core, a plurality of rotor bars, and end rings. The rotor bars are at located in rotor bar openings at a periphery of the rotor. At least one of the rotor bars has a different cross-sectional area than one of the other rotor bars.

Abstract: A squirrel cage type electric motor rotor assembly includes first and sec end plates of circular configuration, rigid tubes extending from the first plate to the second plate, the tubes being closed at either end thereof to define enclosed chambers therein, and granules of magnetic material disposed in the chambers, the granules being packed therein with a density leaving them readily movable to align with magnetic fields.

Abstract: An induction motor includes a stator defining stator inner and outer diameters extending about a longitudinal axis, the stator includes a plurality of windings extending longitudinally and circumferentially about the longitudinal axis between the stator inner diameter and the outer diameter and passing an electric current therethrough to create a magnetic field, a rotor extends along the longitudinal axis having a rotor length and a rotor outer diameter less than the stator inner diameter, the rotor being rotatable about the longitudinal axis relative to the stator, the rotor includes at least one electrically conductive bar having a radial outer end and an inner end, the outer end having a notch, the at least one electrically conductive bar extending parallel to the longitudinal axis adjacent the rotor outer diameter for receiving an induced current due to the magnetic field.

Abstract: A series motor for an appliance or tool, such as a circular saw, includes a regenerative braking circuit having brake windings in addition to the run windings. One of the brushholder assemblies includes a push-away feature for separating one of the brushes from the commutator prior to the time the brush could wear to an extent that direct current reversal might not be available to achieve the desired braking action.

Abstract: The present invention pertains to an improved rotor bar design and method of fabrication of asynchronous motors using such rotor bars. The rotor bar design employs "T"-shaped rotor bars that are interleaved around a magnetic core forming a rotor having a minimum amount of bonding interfaces between the rotor bars and end ring portions. The "T"-shaped rotor bars may either be formed from a single piece or from multiple pieces of copper. The single piece rotor bar method provides N bonding interfaces per end ring, where N is the number of rotor bars used. Where the "T"-shaped rotor bars are formed from three pieces for a rotor having N rotor bars, there will be 2N bonding interfaces for each end ring. Also, the "T" shape of the rotor bars may be added after straight rotor bars have been installed in the rotor bar channels in the magnetic core with their end portions extending beyond the rotor bar channels.

Abstract: A synchronous motor includes a unitary rotor, a first stator, a second stator and phase-changing switches. The unitary rotor has a first rotor portion formed by a first permanent magnet and a second rotor portion formed by a second permanent magnet and an induction type rotor and these first and second rotor portions are mounted on a common rotary axle with a predetermined space provided therebetween. The first stator faces the first rotor portion for producing a first rotating magnetic field. The second stator faces the second rotor portion for producing a second rotating magnetic field and is disposed such that, at the starting operation, the attracting action or the repelling action produced between the first rotating magnetic field and the first permanent magnet is canceled by the repelling action or the attracting action produced between the second rotating magnetic field and the permanent magnetic field.