CA2155218C - Multi-phase electric machine with offset multi-polar electric pole units - Google Patents

Abstract

Known multi-phase electric machines have conductor lanes which do not sufficiently utilize the space available in the grooves and winding overhang or which are costly to produce. Besides a good utilization of the available space, the length of the conductors in the winding overhangs should be kept short in order to obtain high effiency and power densities, and the number of different conductor designs should be minimized in order to reduce production costs. According to the invention, the electric machine consists of several electric pole units which have each a small number of phases and poles with alternating polarity in the direction of displacement. The electric pole units are located next to each other in the air gap and are mutually offset by a fraction of a pole pitch with respect to the rotor poles. Their meandering rectangular conductor wires extend in layers parallel to the air gap. In monophase electric pole units, the conductor insulation is designed for only a fraction of the terminal voltage; by small increments a high effective conductor proportion is achieved. The modular design allows electric machines to be assembled from a few different structural shapes which, because of their simple design, may be produced on a large scale in a totally automated manner.

Description

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TITLE
MLJL.TI~PHASE ELECTRTC MACHYNE
WITH OFFSET MiJLTr-POLAR ELECTRIC POLE UNZTa BACKGROUND OF THE INVF~TTZON
1. Field o~ the Invention The invention concerns a mufti-phase electric machine as wel_1 as a production process for such a maohine.

2, Description of the Prior Art ~n the production of mufti-phase electric machines which are operated ~xt high currents and voltages, the insulation of intersecting conductor lanes requi.xes increased manufacturing expenditures. Tn order to attain high efficiency and power densities, the proportion of the conductor in.'re3.ation to the groove volume should be as large as possible and the proportion of the conductor length in the wind~.ng overhang should be as small as possir~l.e.
US-PS 4,398,112 describes a layered winding fnr disk armatures and linear motors in which stamped conductor layers are inserted into the grooves from the aa,r gap in direction of the groove depth. This results in ~xery short lengths of all conductor lanes in the winding as described in said ~;atent document, however, because al,l conductor lengths of da.fferent phases have different distances to the air gap, the groove volume is completely utilised only iri single-phase machines. 5ingle-phase machines, however, show strong variations of trrque. rn two-phase machines ~ui.th windi.r~gs in accordance with the said United States patent document the utilization ~at~tor o~ the grooves would already drop to 50~, and in three-phz~se .machines to 33~.
From GB-A-1" 0~~,9, O10 a three-phase ref uctance machine with axial ai,r gap ~.s known, the spooled stator of said machine being arranged between two rotor disks. The number of eleck;ric 2~~~~18 J;1L-,~~5 T~1E 1~:4~ Atvi JHP~;'~-:iJ~T:Tr=TE HA:~ ids:. '4i~2~3~4~< ~. 1Z -poles which are evenly distra.buted over the circumference of the stator amounts tb three times the number of teeth in one of the identical rotors, and a soft-magnetic rotor tooth savers one half of the air gap surface plane which is occup~.ed by three adjacent electric poles. Three successive electric poles belong each to different phases, and successive electric poles cf the same phase are wound in opposite direction to each other arid are switched in series. The magnetic utilization of of the air gap surfa~:e plane is here below 50~ and in spite of a large ~Uantity of winding, only low utiliaat~.an factors are attained.
zn GB-A--945, 032 ca small, single-phase high trequer~cy generator is described which is characterized by its extremely flat design. A printed winding' with mea.ndev-shaped conductor progression ~.s arranged on a mufti-polar permanent magnet ring.
Between the windings at the air gap axe soft-magnetic toGth groups where the distance between teeth of adjacent pales ~.s larger than the spacing of the. teeth within the poles.
Further, from Ep 0,341,867 A1, a two-phase stepping motor is known whose winding consists of two conductor rings which are arranged axially side-by-side. Each conductor ring is encased by an unlaminated sheet metal housing which is toothed an the interior surface in the radial direction toward the rotor, the toothing of the two identical halves of the steppi.nc_t motor being offset, against each other by 180°.
Z'he invention is based on the objective to advance the development o~ a mufti-phase electric machine and a manufacturing process of this machine in such a manner that high efficiencx arid power densities with concurrent low t~J~mic losses are achieved, as well as material-saving, easily automated and, therefore, cost--effective production is rztade possible.
~UMMA~tY f~~' '~'~NTrON
In accordance with the invention, this objecti a is achieved by the characteristics of claim 1. and 7.

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A machine in accordance with the invention consists of several electric pole units, the number of phases of each. said electric pole unit corresponding to a fraction of the number cf phases of the machine. In the direction of movezr~ent, or in. the direction of the gxoo~'e width respectively, the electric pole units possess several pples of alternating polarity with the pole pitch within one electric pole unit being constant. Tne associated rotor or stator possesses this pole piG.ch aver' i.ts ent7~re cl,xCUmtereriCe (or its length, respectively). The number of phases of the machine compared to the number of phases of the electric pole units is multiplied by arranging rigidly connected eJ.ectric pole units which are offset against each other by a fraction of a pole pitt~h with reference to the rotor polAs of the machine.
These preferably single-phase or two-phase e3.ectric pole units a.re arranged successively either in direction of the groove depth, in direction of the gzoove or in direction of the groove width and possess conductor lanes of a xectanc~ular cross section, fihe conductors run in meander ehaped layers and partial.
areas within soft-magnetic bodies, said layers an6 partial areas progressing para11e1 to the air gap and perpendicular to the direction of movement.
In an advantageous embodiment a multi-phase electric machine consists of identi.cr~l single-phase electric pole units, the number of said electric pole units cQrrespanding to the number a~ phases or a whole number muJ.tiple of it. In this configuration the conductor ~.nsulation needs to be designed far only a fraction of the terminal voltage, Tn machines with a plane air gap the entire conductor assembly consists of only two disk-shaped structural conductor designs. The grooved soft-magnetic body can be produced as a single unit or assembled from one structural tooth segment shape and two yoke segment shapas.
Including the groove wedges each electric pule unit consists then only of six simple parts which, based on their large n~~mber of 2~~~2~8 JUT-31=55 TUE 1:51 ;Id JAPA?~-TPdS'TiTUTE FEK rd0. ?~'.224334~ D. l4 units, can be produced cost-effectively i.n an automated production facility.
In machines with an even number of phases it is advantageous to coordinate two electric pole units which are offset aga~.nst each other by one ha~.f pole pitch with one rotor disk, and the nuznlaer of rotor disks corresponds to one half the number of phases. A three-phase machine can, howe~ter, also be constructed from three rotor disks and si.x slectric pole units.
Larger, rotating machines, an the other hand, are separated into several identical sector-shaped electr~.cal pole units, in which case the interfacing grooves are of a design that is wider by a fraction of a pole pitch. $y this symmetrical segmentation of the machine into a,dentical electric pa~.e units production and handling of the entz~re machine is also simplified.
The drawings present advantageous ernbodi.ments of the invention.
RIEF DFSCRIRTIaN 0~' THE DRAWINGS
Figure 1 sP.ows a longitudinal section of a ~our-phase disk armature with external rotor design;
Figure 2 shows six lateral views in accordance with section A - A to F - F through the thirty-pole disk armature from Figure 1;
Figure 3 shows three tangential. sections tYjrough the active parts of four-phase mack~ines;
Figure 4 shows five structural designs of four-phase linear motors;
Figure 5 shows a longitudinal section through the gr4oved stator of a three-phase disk armature with six five-pole sectors;
Figure 5 shows a longitudinal section through the 32--pole rotor with permanent magnets belonging to the disk armature from figure 1;
Fa,gure 7 shows the assembly of the tooth segments and groove wedges fox a four-pole sector of a linear motor;

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Figure 9 sk~ows how the conductor stack from Figure $ i,s slid onto the teeth from Figure 7;
Figure 10 shows how the asse:nbl,ed four-pole sector a.s stabi~.~.zed by sliding in of the yoke segments:
Figure 11 shows a profiled Conductor with variable cross section tar a radial air gap machine;
Figure 12 shows a lcangitudlnal section through a device for the preassembly of a four-pole sector winding of a radial air gap machine with a profile conductor, DETAILED DESCR'IPTTON OF THE PREFERRED EMB(JbI. MENT
Fa.gure 1 shows a longitudinal seCtion~of c~ four-phase disk armature with external rotor design , The ~.zzternal carrier body (1) contains a hollow space through which a coolant (2) is c~.xculating. In the assembly, first the two inner prefabricated electric pole units (3b, 3c) are pressed on in axial direction.
This step ensures the tangential offset of one quazter pole pitch each by the cux~re.nt supply and current derivation (4j which ruilS
in insulated grooves (5j of the inner carrier body (1) in axial direction to the outside. Subsequently, the two identical rotor disks (6a, 6b) together with their inner bearings (7) and the two outer electric pole units (3a, 3d) with their cooling bodies (8) are pressed on in axial direction. During the axial sliding on of the tube shaped packet shell (9) the prominences (10j of the rotor disks and the spacer bars (11) ensure a frictional connection that is free from play and exact posita.oning of the rotor disks. In a final step, the two outer bearings are pressed on.
Figure 2 shows six lateral views in accordance wa.th sscti.on A - A to F - ~' through the thirty-pole disk armature from Figure 1 with the haCching patterns being retained. The four identical electric pole units (3a~3d) ax'e rotated by a fraction JUi,-31-~5 T1JE 1L:5L Alvl JAPA:s-INST'.TL'TE FS~ SID. 1~'.??a3';4'?? >J. 1E.
of a pale pitch in relation to the two coincidentally arranged rotor disks (&a, 6b). The electrio pole units (3a, 3b) anc~ (3c, 3d) respectively associated with a rotor disk are rotated ir~
relation to each other by one half pole pitch. The rotation between the two groups amounts to az~e quarter pole pitch, The complete conductor assembly consists o~ two cor~ductox~ layers (i3a, 13b? which are stacked on top of each other alternatingly offset by one pole pitch. They are distinguishabJ.e by different hatching angles and hatching densities, while the raft-magnetic body (14) has concentric circular hatching. The conductor layer (13a) i$ visible only in the two winding overhangs (15) where it utilizes the recesses in the conductor i.ayer ('13a) to double its height, The current passes in each conductor layer (13a, 13b) in a meander pattern through the entire circumference of the mack~ine minus one pole pitch. In this gap occurs either the current supply and current derivation (4) for the drive or the transition to a aonductox layer which lies adjacent in the direction of the groove aepth. ~~he rotor disks (~a, &b) can be assembled pole patch by poi.e pitch wish the soft or hard-maqneta.e sec"~nents being fixed in non-magnetic mountings.
'the three tangential sections through a lineariaed four-phase machine illustrated in Figure 3 shows the tangential offset of the electric pole un~.ts and the progression of tile magnetic flux in hard and soft-magnetic sec~~ner.ts respectively.
The ~.op dr~.wing of Figure 3 sho~,rs a sector corr~prising pole pitches in which, analogous tc~ Figures 1 and 2, the hatching and the reference numbers have been retained but the groove depth has been reduced.
In the middle drawing of Figure 3 the field progression of a permanent magnet e7.ectric machine without consideration of the magnetic field of the windi:~.g is shown. The advantageous current flow direction, for this rotor poJition is depicted by two circular symbols each in the grooves in which a paint wi.t:~in a Gircl.e symbolizes the'current flowing towards the viewer and a -s-2~~~~~.~
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cross within a circle symbolizes the cuxrent flowing away from the viewer. In order to guide the magnetic flux, slots are added in the tangential center of the teeth of the soft.-magnetic bony (17) , The grooves of the electric ~SO3.e unit (16a) lie opposite the rotor pole recess. The carrespondi.ng phase is i,n the process of comznutatiaxl and t.herefare depicted as current-less . On the other hand, electric pole unit (lbb) c~eveJ.ops its full torque.
The electric pole units (16c) and (15d) which are also rotated by one half pole pitch in relation to each other can make a positive cantribuGion to the desired torque as well, The right rotating rotor disk cons:~gts of axially magnetized rare earth magnets (7.t~) which are fixed in their position by a fiber-reinforced mounting (J.9) .
Tn the bottom drawing of Figure 3 the progression of the magnetic field is shown in a four--phase reluctance machine.
The electric poJ.e units (20a-20d) are always energi~.ed when ;by a movement of the snft~magnetic segments (21) towards the right the magnetic resistance far the magnetic field is decreased, zn the rotor position shown in the bottom drawing of Figure 3 the field generated in electric pale un~.G (20b) has reached its lowest magnetic re$istance and the current that was f):.awing up t.o this moment in the conductors (22) is now discannerted. The magnetic field in electric pole unit (20d) now generates a force which moves the rotor in the direction to the right. Such reluctance machines caz~ also be utilized as stepping rnntors.
In Figure 4 five arrangements of electric pole units in four-phase linear motors are Shown.
Figure ~a shows a simple strucC_ural design of a foux-phase litzear motor i n which the four elt~r~tric pole un~.ts ( 23a~
23d) are arranged sequentially in the running direction. The spacing (24) between the identical electric pole units is one quartex pale pitch. The spacing can lie percesved frazn the yokes (?~). The grooved stator bar (26) which consists of saft-magnetic material is integrated into the guide bar over its total 2.2~~2~8 JIJL-~~5 TU~. 1;:'~~ hlvf Jy~al-iNST:Tt~TE FhK ~I~). 1_4i?'L4~3~'~L F. i~
length. The movable part (27) which i.s normaJ.~.y firmly connected with the electric pole units is shown shifted upwards in order to better clarify the three~dimensi.onal arxangemer~t.
Figure 4b shows an embodiment in which the mo~rable part (29) possesses fourt.Een hard-magnetic segments (28) in order to cover four three-pale electric pole units (3a) which in turn show a distance between each other of one quarter pole pitch and in which individual electric pole units are supplied with current only, i.f they are at least in part energized by the perm-~nent.
field.
For movable parts which are shorter in the direction of movement the electric po3.e units (31) - as shovin in Figure 4c -are arranged side by side perpendicular to the running direction or in the direction of the grooves respectively.
Tf a movable part with small overall lengthwise as well as crosswise dimensions is desired, the arrangement shown in Figure 4d is recomrnended in v~thich the electric pole una,ts (32) are arranged sequer_tially in the direction of the groove depth.
The active parts of the movable part or the stator (33) protrude skid-like between two respective electric pale units which are offset against each other.
Figure 9e shows an arrangement with a movable part (35) which ~.s, in relation to the electric pole Tanits (34), very large. The active parts axe arranged laterally on the segment bars (35) which reach horizontally into the movable, part. In order to compensate the torque, two respective electric pale units of the same phase are arranged in diagonally apposite corners at the movable part.
Of the s.ix identical sectors (37a) to (39b) which are shown in Figure 5 two respective sectors that lie opposite to each other belong to one phase. The conductor stacks consist of two stamped parts (40, 41) which are alternately stacked oz~ top of each other. In the widened interfacing gxoov~e (42) the conductors of differing phases are separated by a thicker 21~~~1~
JUT-~~5 TUu 1~;5T ~i'~ ,)y~r,(d-I~I~T~ TLrTE FF'~ '~I~1. ~41L''"' a~~~' L ~ ~ _ ~ .. L , 19 insulating layer. The distance Qf the radial center ~.inas of the r,im teeth of adjacent sectors amounts to four thirds of the normal pole pitch which, on tk~e other ht~nd, corresponds to the pole pitch of the movable part.
While the rotor, as shown in Figure 6, is constructed symmetrically of thirty-two identical magnetic poles (43) which are embedded in a plastic body (44), the stator possesses six broader interfacing grooves (42) in order to generate differing phases and only thirty poles (45).
Figures 7 - 1Q show the assecrbly of a faux-pole sector for a linear motor. The depicted structural design - curved around various axes - is also applicable in a~cial and radial air gap machines.
Tn the assembly of the sectors, as shac~rn in Figure 7, the tooth segments (~lfi) with insulating plates (4'7) and elastic groove wedges (48) are joined first in tkzeir final position. The insulating plates fill the narrow flux guiding grooves (4~) in the center of the tooth segmezats and the groove wedges ensure the spacing between the tooth segments and avoid air noise. 4~7ider groove wedges (50) are required for the wider intezvacis~g grooves.
In Figure 8 the assembly o,t a ten-layer conductor stack (51) for the four-pole sector from Figure 7 is depicted. The five conductor parts an the left already constitute a compact stack, while the remaining five conductor pants are added ~,n pairs or singly. Each conductor stack of the mufti-phase linear motor consists of two stamped structural conductor designs, where besides the supply and derivation conductors (52) eight normal conductor layers (53) are insert~e~l. I~ftex sliding the conductor layers together, they are welded together at the interface edges (54) .
Zn F~.gure 9, the functional conductor stack (51) is pushed onto the tooth segrnents t46?.
Finally, as shown in Figure 10, the yoke segments (55, 56) are inserted in direction t~f the groove into the tooth.
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segment ends (9:6a) which protrude from the conductor stack (51) causing the conductor stack to be pushed against the elastic cgrQC~ve wedges (48, 50} and achieving an assembly that is free from play and which can be disassembled at any time again.
6esi.des the normal yoke segments (55) wider yoke segments (SS) are required far the interface grooves to the adaacent ~.dentical sectors of Qther phases which, as, an alternative to the noxznal mufti-layer yoke segments, may consist of ferrite.
Alternatively to the prefabricated man-curved conductor lanes, the partition of the mufti-phase machine iritd single-phase electric pole units can alst~ be executed ad antageously by profiled conductors, since the conductor progrESS~.on of s~.id electr~.c pole unite xs non-intersecting.
in Figure 11 a rectangular profiled conductor (57) for a radial air gap machine is shown, whose conductor cross section is altered over predetermined longitudinal sections by a preprogrammed rolJ.ing machine (59) prior to application of the insulating matex~zal in a Coating facility (58). The longitudinal Se~~.ionS with COT'A~tdn~ croSS SBCtian GOx're~pOnd to the canduGtQr lengths of the layers which lie paralhel to the aa.x gap, thereb~~
changing the width of the conductor in proportion to the radius at each transition to another layer.
Figure 12 shows a deva.ce (6D) in which a self-contained four-pole sector winding (61) for a radial air gap machine is prefabricated. The parts ref the device (62) corresponding to the teeth are inserted into a base body (63) and possess comically tapered ends (64) a.n order to facilitate the insertion of the ConciuCGor. In the wider ~.nterface grocweg (65) the inclined partial lengths of the conductor lane (66) are ~.nserted ~.nto alignment bodies (57) which consist of an insulating high-strength plastic. After radial pulling out of the tooth pants ( 62 ) ar_d prior to removing the prefabricated 5eCtal WlIlt~lY'lg ( 61 ) , said winding being rendered self-contained by a binding agent, together with the groove insulation from the device (60) the partial, oanductox lengths in the interfacing grooves (6S) are once more deformed by pressing them tangentially into the solid alignment bodies (~7). The illustration shows the partial conductor lengths already pressed together in the left interfacing groove (65') and not yet pressed together in the right interfacing groove (65). 8y tangential combining of the sector wi,n.dings (61) wh~.ah are only separated by thin insulating plates (~8) the complete winding of the mufti-phase machine is achieved.

Claims (7)

CLAIMS:

1. A multi-phase electric machine comprising at least one stator and one moving part, said stator being separated from the moving part by an air gap, said stator or said moving part containing at least one soft-magnetic body with grooves, said grooves having a width, a depth, and a length, and located between said grooves are poles where the distance of the central line of adjacent poles is one pole pitch, and arranged in said grooves are conductor lanes and in said soft-magnetic body can flow a magnetic flux, wherein the machine contains at least two multi-polar electric pole unit, the number of phases of said units being smaller than the number of phases of the entire machine, the poles of the electric pole units show alternating polarity in the direction of the movement of the moving part, the magnetic flux flows in the electric pole units through soft-magnetic material, the conductor lanes progress in layers parallel to the air gap and in meander pattern in the direction of movement of the moving part over the entire length of the respective electric pole units, the conductors are of a rectangular cross section within the electric pole units, the pole pitch within each electric pole unit is constant, the pole pitch of the moving part or stator is constant over the entire circumference or length of the machine, said moving part or stator lying opposite the electric pole units at the air gap, some of the rigidly connected electric pole units are offset by a fraction of a pole pitch against each other with reference to the moving part or stator poles which the opposite said electric pole units, the electric pole units are arranged successively in either the direction of the groove depth, in direction to the groove or in direction of the movement of the moving part.

2. A multi-phase electric machine as recited in claim 1, the moving part thereof being a rotor, said rotor possessing an axial or radial air gap and rotating in front of the stator, wherein the electric pole units are designed as sectors of the machine circumference, the conductor lanes progress only through a fraction of the machine circumference, interfacing grooves lie between two adjacent units, and the width of said interfacing grooves between two tangentially adjacent sectors of electric pole units is larger by a fraction of a pole pitch than the width of the other grooves within a sector.

3. A multi-phase electric machine as recited in claim 1, wherein the number of electric pole units of said machine corresponds to the number of phases of said machine, or a whole-number multiple of the number of phases respectively, and wherein all electric pole units are of a single-phase and identical design.

4. A multi-phase electric machine as recited in claim 1, wherein conductor lanes which lie on top of each other, being separated only by thin insulating layers, and said conductor lanes, offset against each other by one pole pitch, progress in direction of the groove width, said conductor lanes lying directly adjacent to the magnetic body, and said conductor lanes, in partial areas that progress outside said grooves in direction of the groove width are enlarged in relation to the remaining partial areas in direction of the groove depth.

5. A multi-phase electric machine as recited in claim 1, wherein two identical electric pole units are arranged on opposite sides of a rotor or stator, said electric pole units being offset against each other by one half pole pitch in direction to the groove width.

6. A multi-phase electric machine as recited in claim 1, wherein additional identically designed electric pole units are intended to move the same movable structural part and in which the moving parts are firmly connected with said movable structural parts, and wherein said electric pole units are offset with reference to the poles of the moving parts by the respective fraction of a pole pitch which corresponds to the number of phases, and wherein a coolant is circulating between two electric pole units.

7. A multi-phase electric machine, comprising at least one stator and one moving part, said stator being separated from said moving part by an air gap, said stator or said moving part containing at least one soft-magnetic body with grooves, said grooves having a width, a depth, and a length, and located between said grooves are poles and arranged in said grooves is a prefabricated rectangular-shaped profiled conductor which is coated with insulation material, said conductor having variable conductor cross sections and being designed in meander-shaped layers and said layers and said soft-magnetic body constituting a single-phase, multi-pole electric pole unit, and the machine is consisting of several such electric pole units.