Anchor electric dc machine
(57) Abstract:The invention relates to the field of electrical engineering, namely electrical DC machines and can be used in the design of traction motors, ship crests electric motors, excavators, etc. the Invention solves the problem of creating the design of anchors, allowing to obtain the minimum weight and dimensions DC machine with a low level Zubovich harmonic vibrations. For this purpose, the active length of the anchor, each winding layer are composed of alternating between a covered winding insulation of the conductors of the coil and ferromagnetic elements, in particular laminated trapezoidal cross-section. On each winding layer superimposed bandage in the form of a continuous coating of electrically insulating material, in particular glass-fiber tape. 1 C. p. F.-ly, 1 Il. The invention relates to the field of electrical engineering, namely electrical DC machines and can be used in the development of machines of medium and high power, e.g., traction motors for locomotives, trams, trains), ship propeller motors, electric motors, excavators, pretannage current are reduced weight and performance and reduced vibration.One of the main obstacles in this direction is the application of the most current designs of electric machines gear anchors. The conductors of the winding are placed in the slots between the teeth and are separated from the surrounding groove iron electrical insulation, the thickness of which, depending on its type, operating conditions of the machine, and also taking into account experience of mechanical engineering, machines for medium and high power with a nominal voltage of about 0.5-3 kV up to 1-1,5 mm on a side (see Alekseev, A. E. Traction electric machines and transformers. L. Energy, 1977, S. 304).During the rotation of the armature occurs a periodic change in the number of teeth under the pole of the machine, which causes pulsation of the magnetic flux with a frequency proportional to the number of teeth, and, as a consequence, there are corresponding components in the spectrum of the vibrations of the machine ("subtopia harmonic").A possible way to reduce the amount of insulation in the winding layer and eliminate Zubovich harmonic vibration is shifting to the use bezzubova design anchor ("smooth anchor"). The turns of the winding in the anchors of this type are placed on the insulated surface of buzz is ten several designs of DC machines with a smooth anchor (see auth.St. N 394895, H 02 TO 3/46, 1973.).The common disadvantage of these machines, due to the absence of conductive elements in the wrapping layer is the large size of the nonmagnetic gap. Especially it appears in the machines of large capacity, respectively, and having a greater thickness of the wrapping layer. The increase of the consumption power in the excitation winding leads to poor efficiency and growth massoumi performance of the machine, causing the machine constant current with a smooth anchor currently find application mainly in low-power systems automation (see Electric motors with smooth anchor for automation systems. Ed. by Y. K. Vasiliev. M Energy, 1979).In the inventions according to ed.mon. N 917262, H 02 TO 1/06, 1982. winding is assumed made of bimetallic material consisting of conductive and conductive parts. Through the ferromagnetic material (steel) is part of the total electric current of the winding, resulting in increased current load winding layer anchors. However, in machines of direct current application of the windings of the bimetal is impractical for the following reasons.The presence of ferromagnetic elements in labovitch threads mutual induction with the other sections. As a consequence, increases the amount of reactive EMF and will worsen the process of switching (see Waldeck A. I. Electrical machines. M.-L. Energy, 1966). By increasing the magnetic conductivity of the end parts of the winding of the rotor will increase the flow of scattering the main and extension poles.Parallel connection of copper conductors to steel cores will lead to the reduction of the electrical resistance on the path of the induced eddy currents in the steel, and therefore, increase the corresponding power loss, especially at high frequency alternating magnetization (20oC 50 Hz).In addition, as proposed in the above inventions, the design of the armature winding, is intended for use on stationary (stator) part of polyphase AC machines and practically can not be realized on the rotating rotor of the DC machine.Any technical solutions aimed at reducing machine vibration subcatego nature (arising from the introduction in the current layer of ferromagnetic elements), considered the proposals do not contain.On set of core characteristics (type of current machine, the design and method of attachment ostavlennoj in ed.St. 394895, H 02 TO 3/46, 1973. which was adopted for the prototype.In the known construction the winding is placed on an isolated surface bezzubova anchors, fixed brace and attached to the armature core in the form of a monolithic layer.Such design provides easy mounting of the wrapping layer on the anchor, the absence of electromagnetic vibrations subcatego origin, but has a total lack of cars with a smooth anchor increased non-magnetic gap, leading to a deterioration massoumi performance of the machine (or lower efficiency).The task of the claimed invention is to provide a construction anchor DC machine, which allows to obtain the minimum Massabielle performance machine with a low level Zubovich harmonic vibration.This is achieved in that the active length of the anchor DC machine containing bezzubova the magnetic core and fixed by a band of insulating material and zamonolichennyj with him winding, each winding layer is selected from alternating between the covered winding insulation of the conductors of the coil and ferromagnetic elements, for example, laminated, for example, tropeziennes material, for example, fiberglass tape. The thickness of the ferromagnetic elements is not greater than the value of the total non-magnetic gap of the machine.The presence of the wrapping layer of ferromagnetic elements provides sufficient magnetic conductivity for the main magnetic flux, and the small volume occupied by the insulation layer (only a thin winding) the possibility of obtaining high levels of fill layer conductors. As a consequence, reduces the required MDS field windings, and the total mass and volume of the machine with the anchor of the proposed design is less than the anchor adopted for the prototype or jagged.Unlike the prototype during the rotation of the armature of the proposed design, you may experience vibration machine subcatego nature due to the presence on it of the ferromagnetic elements. However, the adoption of certain constructive measures the vibration level can be reduced to acceptable values.As is well known (see Lubov I., Noise and vibration of electrical machines. L. Energoatomizdat, 1986), the value of the main pathogens vibration DC machines electromagnetic origin alternating forces acting on the pole when prohozhdenie the down reduced, with a relative decrease of the width of the tooth.In machines with toothed anchor through the teeth on the core of the rotor is transmitted torque machine (electromagnetic forces acting on the conductors located in the groove and, therefore, the width of the tooth at the base cannot be less than allowable under the terms of its mechanical strength. In the car with a smooth anchor and zamonolichennymi winding layer of torque transmitted through the wrapping layer, and a ferromagnetic insert, through which the magnetic flux, do not perform the functions of the main elements for torque transmission. This allows you to take when designing a machine width of the ferromagnetic inserts smaller than the machines with toothed anchor, and to reduce the vibration level.Satisfy the majority of practical cases, and significantly less than the machines with toothed anchor the vibration level from Zubovich harmonic can be achieved by reducing the thickness of the ferromagnetic elements to values smaller than the value of the non-magnetic gap of the machine (as defined by the total amount of primary air gap and radial thicknesses of the Cabinet, the interlayer and the outer insulation of the windings).The drawing shows a schematic cross RA is performed as follows.On the shaft 1 is mounted a core 2 made of sheets of electrical iron. On the cylindrical outer surface of the core stacked layer encasing the insulation 3. This layer is placed a rod conductors of the lower layer coil 4, is covered with winding insulation 5, and turn to them (in the tangential direction) of the stacked ferromagnetic elements of the rods 6, the length of which corresponds to the active length of the machine.Ferromagnetic elements 6 have a cross-section in the form of a line extending in the radial direction. Such design allows the best way to fill the volume between the conductive terminals and to provide a minimum magnetic resistance in the path of the magnetic flux. To ensure small vibration level of the machine the maximum thickness of the ferromagnetic elements does not exceed the total non-magnetic gap of the machine, and at high speeds the machine (magnetization reversal) they can be made of laminated.The lower winding layer, including ferromagnetic elements 6, covered with a layer of insulating tape 7, such as fiberglass, which simultaneously performs the functions of the power band and electrically insulating layer, OTDELA rods 8 and ferromagnetic elements 9, covered external insulation 10 (tie-wraps). All winding layers impregnated and zamonolichennyj in electrically insulating material.Calculations (including, jointly with LPEA "Electrosila"), as well as experimental studies of models of machines of various capacities (including the manufacture and testing of anchors for the tram engine with a capacity of 45 kW) confirmed the possibility of implementing the proposed design. Thus the expected payo by weight compared to the engine with a smooth anchor of known construction will be at least twice as compared with the engine gear anchor 20-40% (depending on machine parameters, power, speed).Proposed to reduce Zubovich components of vibration technical solution was tested by calculation and experimentally produced samples of electric machines (measuring the vibration level). 1. Anchor electric DC machine containing bezzubova the magnetic core and the winding, mounted on the insulated surface of the magnetic circuit using a band of insulating material and zamonolichennyj together with bandage, characterized in that each winding layer on the active is the shaft elements of trapezoidal cross-section, in particular laminated, and a band of insulating material superimposed on each winding layer and is made in the form of a continuous coating, in particular of the fiberglass tape.2. Anchor under item 1, characterized in that the thickness of the ferromagnetic elements does not exceed the total non-magnetic gap of the machine.
FIELD: electrical engineering; electrical machine armatures having odd and even number of turns and odd or even number of section coils.
SUBSTANCE: proposed armature winding may have any desired slot number and has its electrical characteristics as close to arcless switching as possible due to alternate paired entrance of armature winding section coils under electrical machine poles and relative offset of these coils through one tooth pitch is assembled of section coils placed in armature slots. Novelty is that with even number of winding section coils at odd number of sections, respectively, these coils are evenly distributed in each pair of adjacent armature slots on opposite ends of armature axis.
EFFECT: enhanced manufacturability of armature winding.
1 cl, 4 dwg
FIELD: electrical engineering; armatures of rotating electrical machines.
SUBSTANCE: electrical machine armature has shaft and winding whose interconnections are made by means of insulated buses installed in annular-cavity bushing; soldered to insulated buses on armature winding end are jumpers formed by leads in radial direction. Armature coil leads are also formed in radial direction for soldering jumpers and armature coils in same plane.
EFFECT: facilitated manufacture of armature winding.
2 cl, 2 dwg
SUBSTANCE: invention is related to the field of electric engineering and concerns technology for manufacturing of electric machine rotor winding. Method is suggested for manufacturing of electric machine (10) rotor winding, comprising at least four excitation poles (P) installed in stator (11), collector rotor (13), having grooves arranged along circumference and pole teeth (Z), number of which differs from number of excitation poles, sections (S) of winding and the same number of collector plates (L), number of which is at least twice more than number of pole teeth (Z). As sections (S) are wound onto pole teeth by winding wire in continuous mode, after fixation of winding wire (17) on initial plate (La) on the first pole - tooth (Z1) the first section (S1) of winding is wound with selected angle shift (φ0) relative to initial plate (La), then winding wire (17) with specified pitch (Y) along collector is fixed on another collector plate (L), which is a final plate (Le) for wound section, then serially from each collector plate (L) winding section (S) is wound onto pole tooth (Z) with lowest deviation (Wf) of selected angle shift (φ0) from electric angle identified by pole division of stator, afterwards winding wire (17) is entered in contact with another plate (Le), which is spaced by specified pitch (Y) along collector until all winding sections (S) are wound on pole teeth (Z).
EFFECT: provision of low pulsations of rotation torque and long service life due to optimal commutation of winding sections (S).
15 cl, 13 dwg
FIELD: electric engineering.
SUBSTANCE: proposed eccentroid electric machine comprises (dwg. 1-2) body (1) arranged with internal ring in the form of elliptic bearing race (2) from dielectric material, stator made in the form of three inertial elements (3), every of which is assembled from plates of electrotechnical steel, comprises axis (4) of rotation, is arranged in the form of rolls equipped with magnetic belts (5) at the ends, which consist of even number of semirings of various polarity. Axis (4) of rotation of each of inertial elements (3) is connected by two telescopic spring links (6) to dampers (7), installed symmetrically on both sides of rotor system, including propeller blades (8), on driving shaft (9) common for stator and rotor, which is arranged eccentrically relative to geometric axis of eccentroid electric machine. Body (1) is closed with two covers (10) at sides, on which at inner sides there are elliptic angle guide elements (11) installed to form together with elliptic bearing race (2) elliptic closed channel for movement of inertial elements (3) in it. Telescopic spring links are arranged relative to each other at the angle of 120°. Rotor system of eccentroid electric machine (dwg. 3-7) consists of two rotors: rotor (12) of free rotation and rotor (13) of forced rotation, rigidly arranged on driving shaft (9). Rotor (12) of free rotation comprises hollow shaft (14) arranged on sliding bearings (15) concentrically relative to both driving shaft and rotor (13) of forced rotation. Inside hollow shaft (14) of ferromagnetic material there is a system arranged from even number of permanent magnets (16) with alternating poles, and outside their rims (17) - magnetic belts (18) made also of even number of permanent magnets. Magnetic belts (5) and (18) of stator and rotor (12) of free rotation are arranged oppositely, and permanent magnets (16) have length comparable to length of rotor (13). Each of dampers (7) comprises hollow cylindrical perforated ring (21), rigidly fixed on driving shaft (9) and divided with internal radial partitions (23), between which compensation springs (24) are installed with thrust. Ends of telescopic spring links (6) arranged in dampers are arranged with hubs (22) rigidly installed on driving shaft (9), are installed in middle part of compensation springs and come out of dampers through holes in their cylindrical rings.
EFFECT: increased efficiency of electric machine operation by provision of ability to generate additional energy used for self-sufficiency of machine operation in rated mode and for supply to loads, and for production of traction used to provide for ability to use electric machine as propeller.
5 cl, 14 dwg
SUBSTANCE: direct current generator includes stator with poles on which there arranged are excitation windings, armature with armature winding, which is fixed on generator shaft connected to shaft of drive motor connected to alternating voltage source, contact device made in the form of two conducting solid contact rings on which current-collecting sliding brushes are installed. At that, the beginning of armature winding is connected to one contact ring, and the end - to the other one; excitation windings are connected to alternating voltage source, and synchronous motor is used as drive electric motor.
EFFECT: improving reliability of DC generator, increasing its output voltage.
SUBSTANCE: power supply to proposed electric machines at their operation in mode of motors can be performed not only from stationary electric AC mains of commercial frequency with its further conversion to DC, but also from movable and portable independent direct current sources (minielectric power stations, storage batteries and galvanic power elements). Salient-pole commutator machine includes housing made from soft magnetic material, salient poles of inductor with coil excitation winding of inductor, armature with salient poles, commutator, mechanism of brush-and-contact assembly with brushes, closed subsequent (wave) coil armature winding consisting of coils each of which is located on the appropriate salient pole of armature, and beginnings and ends of coils are connected to each other in certain way and connected to the appropriate commutator bars of commutator, thus forming closed electric circuit with two parallel branches. At that, it is necessary to follow certain ratios between the number of inductor poles and the number of armature poles, as well as to make their pole arc of certain width, and commutator bars and brushes of certain width and certain number.
EFFECT: high energy properties of salient-pole commutator machine with high commutation, and smooth control of output parametres at simultaneous simplicity and high reliability of the design of electric machine.
8 cl, 5 dwg, 1 tbl
SUBSTANCE: salient-pole commutator electric motor includes housing, core of inductor with salient poles, which consists of isolated electrotechnical steel sheets with high magnetic permeability, coil excitation winding of inductor, armature with salient poles, commutator, mechanism of brush-and-contact assembly with brushes, closed subsequent (wave) coil armature winding consisting of coils each of which is located on the appropriate salient pole of armature, and beginnings and ends of coils are connected to each other in certain way and connected to the appropriate commutator bars of commutator, thus forming closed electric circuit with two parallel branches. Inductor excitation winding is connected in series in relation to armature winding. At that, it is necessary to follow certain ratios between the number of inductor poles and the number of armature poles, as well as to make their pole arc of certain width, and commutator bars and brushes of certain width and certain number.
EFFECT: high energy properties of salient-pole commutator electric machine with high commutation, and smooth control of output parametres at simplicity and high reliability of the design.
6 cl, 5 dwg, 1 tbl
SUBSTANCE: most close analogue of a proposed machine is a DC machine with a mechanical commutator, a collector with sliding brush contacts. The named machine has certain disadvantages in its design, consisting in the fact that it comprises rotary anchor winding and collector, on surface of the latter in which several pairs of brush contacts slide continuously during its operation. It results in intense wear of its parts sliding against each other from sliding friction, in narrowing of its application field due to sparking that occurs then between them. Besides, the rotary anchor windings somewhat limit the possible maximum angular speed of its rotor rotation. In the proposed DC machine design the anchor winding is fixed, and an inductor rotates, being made of permanent magnets and a central magnetic conductor, installed on a common rotation shaft, besides, instead the movable collector with the brush contacts sliding on them, it applies a fixed collector, made of three hollows cylinders, in inner surfaces of which two pairs of diametrically opposite electroconductive caterpillars move simultaneously, being displaced from each other not only along the rotation shaft by the required distance, but also by 90 degrees along the circle. In this case the fixed collector with electroconductive caterpillars at any time of the rotor rotation provides such current directions in the anchor winding, when in the area of poles of the permanent magnets of various polarity there will always be conductors with opposite directions of the currents. With such distribution of the anchor currents, electromagnet forces from their interaction with the magnetic field of the inductor will act in concord, which makes it possible for the machine to develop a maximum torque. In the generator mode, AC currents are available in the anchor winding conductors of the proposed DC machine, and they arrive along the connecting wires to the fixed collector with movable electroconductive caterpillars, by means of which they will flow into the outer circuit as a certain load, but already as rectified.
EFFECT: significant increase of the machine wear resistance, expansion of its application field and increased reliability in operation.
FIELD: electrical and electromechanical engineering; rotors of large electrical machines such as turboalternators.
SUBSTANCE: proposed electrical machine rotor has heavy wound core whose winding coils are secured in end portions in radial direction by means of heavy metal banding rings fitted with one end on butt-end portions of core and with other end, on cylindrical surfaces of Z-section alignment rings; inner surface of alignment rings are joined with end portions of rotor shaft, two rows of slits being made in vicinity of mentioned rotor-shaft or banding-rind junction surfaces of each alignment ring uniformly and tangentially disposed over circumference of the latter in relatively staggered manner. One row of mentioned slits can be made in mentioned zones within alignment ring and other row, on rotor shaft surface jointed to alignment ring, for instance in the form of cooling ducts.
EFFECT: enhanced reliability due to additional reduction of alternate stress in zone where banding rings are fitted on rotor core.
1 cl, 2 dwg
FIELD: electric engineering and electro-mechanical industry, in particular, features of design of coils with salient poles for rectangular stators of salient-pole electric machine.
SUBSTANCE: in the coil for magnetic system of stator of salient-pole electric machine with rectangular poles, made by winding of flat rectangular cross-section bus onto narrow rib and containing elements of body and coil isolation with monolithic realization of working part of coil, in accordance to invention, on frontal parts of coil air gaps are provided between coils, expanding in wedge-like fashion in axial direction from the end of magnetic-duct of pole, in gaps between coils in longitudinal symmetry plane of coil distant inserts are installed made of solid isolating material with shape and dimensions, corresponding to gaps between coils in this plane, and with width substantially lesser than width of pole, connected by gluing to surfaces of adjacent coils, a packet of structural elements, consisting of frontal parts of coil rings and distant inserts between them, is fastened in longitudinal symmetry plane of the coil by bandage of non electro-conductive material, resistant to stretching, aforementioned inserts being of orthogonally symmetric H-like form with height of bar, equal to width of bus, and with common height, exceeding it by double bandage thickness, aforementioned bandage being positioned between shelves formed by aforementioned method. Due to such characteristic feature, all four sides of rectangular cross-section of each conductor within limits of frontal part of coil form surfaces, directly cooled by blowing air or liquid, correspondingly to scheme of theoretically full usage of external surface of conductors for their cooling.
EFFECT: increased efficiency of electric machine, increased density of current in windings, resulting in improved mass-dimensional characteristics of electric machine, decreased temperature of windings, and, thus, increased lifetime of isolation, allowing to use isolation of lesser heat resistance which is therefore cheaper or more technologically accessible.
8 cl, 10 dwg
FIELD: electro-mechanical engineering.
SUBSTANCE: bandage of electric machine anchor winding is made in form of continuous solid coiling, coil to coil, in a layer of isolated wire of magnetic or non-magnetic material at whole axial length of bandage section of winding, which does not have other means of radial attachment. The bandage contains even number of wire layers with a lock of beginning and end of coiling on one of end sides. Below each single or double layer of wire, an insert ribbon is positioned which envelopes the anchor surface being bandaged in one layer and which is made of non electro-conductive reinforced material containing axially oriented direct threads rigid to stretching. Aforementioned insert ribbon is provided with collar stops on external surfaces along end edges. Collar stops are longitudinally reinforced with wire or non-metallic filaments rigid to stretching. Axial distance between their internal stopping surfaces is equal to axial size of surface being bandaged.
EFFECT: simplified construction, ensured maximal technically possible reduction of losses to vortex currents, ensured stable reliability.
4 cl, 8 dwg
FIELD: engines and pumps.
SUBSTANCE: invention relates to perfection of borehole generators, particularly, to support and limitation of displacement of stator coils arranged in the engine housing. Borehole motor has tubular housing elongated in lengthwise direction, stator part arranged therein, stator coil winding looped back in the stator by end turn with tip. It comprises connector to connect at least one of coil windings and housing end abutting on stator part end to support the winding.
EFFECT: fastening of stator coils not coated with lacquer inside motor housing.
17 cl, 5 dwg
SUBSTANCE: invention is related to the stator of electrical machine and the method of its manufacturing. The stator for electrical machine comprises the core having a variety of pole horns and a variety of windings made of electroconductive material at pole horns. At least a part of windings is made of a wire having a pair of free ends, which may be connected electrically to the network power source. The stator comprises two or more electric contacts having a flexible section, which may be moved in direction towards the core and away; the above contacts are connected electrically to the respective contacts of the power source. At least one of electrical contacts is formed by two free ends of the corresponding different wires and has a twisted shaped made by ends twisting along the initial line of the ends passing, at that at the base of each twisted part there is a loop for each electrical contact. The loop forms a dampening element for the respective twisted section.
EFFECT: improved reliability of the electrical machine.
21 cl, 20 dwg
SUBSTANCE: invention is related to electric engineering and may be used at production of submersible borehole pumps, electric vehicles, in particular hybrid vehicles, and battery vehicles. Winding of double-pole three-phase electric machine is made with number of slots z=18, c pitch of y=1-10, with number of parallel branches a=1 and ratio of number of turns in even delta-connected coils to number of turns in odd wye-connected coils equal to √3. Winding includes six single- and double-layered two-section coils with ratio of turn number in single-layered sections to turn number in double-layered sections equal to 2:1. Coil beginnings of wye and delta phases with the same polarity are shifted per 2 slots (40 electrical degrees). The coils are laid in waggle way and their outputs are placed from outer sides of coils or outputs of only even coils are placed from their inner sides. According to another version outputs of coil beginnings of wye and delta phases are placed in the common slot (shift is equal to 0 electrical degrees, at that at inner sides of the coils there are outputs of odd coils only or outputs of all coils.
EFFECT: implementation of double-pole three-phase energy-efficient and low-noise electric machine with number of slots of z=18, with pitch of y=1-10 and number of parallel branches of a=1.
2 cl, 4 dwg
SUBSTANCE: invention is related to electromotive machines, and more specifically to devices designed to support to insulate thermally superconducting coils of rotor. The device for support of superconducting coils at separating distance from the core of the machine rotor comprises an elongated circuit designed to serve as radial support for the coil, axial main assembly (84) made with potential fixing of the above circuit in regard to the rotor core at near end of the elongated circuit in regard to the rotor axis and bracket assembly designed to set inner depth for receipt of the superconducting coil section and to support elongated circuit at its remote end in regard to the rotor axis. The elongated material contains material resistant to heat flow. The axial main assembly comprises a modular assembly including the main module placed in cavity of the rotor core.
EFFECT: developing structure ensuring reliable support and heat insulation of the superconducting coil.
10 cl, 16 dwg
FIELD: electrical engineering.
SUBSTANCE: invention is related to electrical engineering, particularly, to generators of electricity. Power generator comprises of the stator with the base, including ring or torus and multiple pins or extending outward from the ring or torus, intended for rigid installation of the base of the stator on the mounting support of the stator, as well as winding conductors wound around said ring or torus. Generator also contains the erection support stator, including base plate, a journal secured to base plate or made integral with it and extending from it, at least on one side, and assembly facilities extending along the periphery of the bed plate, at least on one side. Mounting devices include mounting holes, each of which is intended for reception of one element from the specified multiple pins or the base of stator for rigid installation of the base of the stator on the mounting support of the stator.
EFFECT: technical result is improved design of the generator stator.
17 cl, 7 dwg
FIELD: engines and pumps.
SUBSTANCE: present invention relates to electrical engineering, namely to electric machines manufacture. The motor coil frame comprises the main part of the coil frame, around which the coil is to be wound, and flanged portions formed integrally with both end portions of the main part of the coil frame, wherein the coil frame uncludes a resin-based molded part formed using a polymer with amide linkages and insulating aramid containing paper made from aramid fibrid and short aramid fibers, at that, the surface of the resin-based molded part and of aramid paper are directly connected to each other.
EFFECT: invention provides improved performance and power output of electrical machines.
7 cl, 4 dwg, 2 tbl