WO2008031726A1

WO2008031726A1 - Permanent-magnet synchronous machine

Info

Publication number: WO2008031726A1
Application number: PCT/EP2007/059049
Authority: WO
Inventors: Ralf Kruse
Original assignee: Continental Automotive Gmbh
Priority date: 2006-09-11
Filing date: 2007-08-30
Publication date: 2008-03-20

Abstract

In a permanent-magnet synchronous machine (1) with a stator (2), which has a stator winding (U, V, W) and surrounds a rotor (4) with a rotor surface (4b), which is spaced radially apart from a rotor axis (4a), so as to form an air gap (3), on which rotor surface a number of magnet poles (N, S) which corresponds to the number of poles (2p) are arranged in a circumferential direction (U) with an axial pole width (b) which is delimited by two opposing pole edges (7, 8), the axial pole width (b) of the magnet poles (N, S) varies in the circumferential direction (U).

Description

description

Permanent magnet synchronous machine

The invention relates to a permanent magnet synchronous machine having a stator winding for generating a stator field having stator which surrounds a magnetic pole in the form of permanent magnets having rotor forming an air gap. It further relates to a hybrid vehicle with such a synchronous machine.

Such a synchronous machine with a stator-side, usually three-stranded and fed with a three-phase sinusoidal AC or three-phase stator or rotating field winding has a designated as a pole windingless rotor, which is provided with permanent or permanent magnets. These form alternating magnetic poles, i. H. the north and south poles of the magnetic poles directed towards the air gap between the stator and the rotor alternate along the circumference of the rotor. The total number of magnetic poles indicates the number of poles (2p), with adjacent north and south poles forming so-called pole pairs (pole pair number p).

Independently of a special arrangement of the permanent magnets, these generate in the air gap a so-called rotor field or rotor rotating field. The three-phase, powered stator winding generates a rotating magnetic stator or stator rotating field in the air gap with the number of poles corresponding to the number of poles of the rotor field. As a result of the interaction between the rotor field and the stator field creates a torque of the synchronous machine. In stationary operation, the synchronous machine rotates at synchronous speed by the rotor rotates at a speed corresponding to the speed of the stator field speed. Depending on the angular position of the rotor relative to the stator field this torque is positive - and thus accelerates - or negative and therefore braking. The angular position of the rotor is therefore decisive for a motor or a generator operation of the synchronous machine.

The permanent-magnet synchronous machine offers a high volume-related torque and can incorporate the speed with a high power density, which ultimately ensures a high degree of utilization. However, permanently excited synchronous machines tend to relatively high unwanted torque ripples and in the de-energized state to undesirable cogging torques. These latching or cogging torques occurring due to reluctance fluctuations can lead to undesirably high torque fluctuations and corresponding speed fluctuations when the rotor is practically aligned with the stator teeth during operation. Also disadvantageous are the electromagnetically excited noises.

The torque ripple in an inverter-fed synchronous machine also causes power fluctuations on the DC side (DC side). In particular, when using a synchronous machine in a hybrid vehicle (hybrid vehicle application) such power fluctuations can significantly reduce the life of the high-performance battery of the vehicle.

The invention has for its object to provide a permanent-magnet synchronous machine, in which avoiding said interference effects in the form of, in particular, torque ripples, cogging torques, power fluctuations and / or electromagnetically excited noises enables an improved operating behavior.

This object is achieved by a permanent magnet synchronous machine having a stator winding for generating a stator field having stator which surrounds a rotor to form an air gap. On or on the rotor axis radially spaced rotor surface one of the number of poles of the synchronous machine corresponding number of magnetic poles in the circumferential direction to form alternating north and south poles are arranged. The magnetic poles or their arrangement on the rotor surface have mutually opposite pole edges in the direction of the rotor axis, the distance of which defines an axial pole width. This axial pole width of the magnetic poles varies in the circumferential direction.

By varying or changing the axial pole width of the respective magnetic poles in the circumferential direction of the machine or of the rotor, the axially-mediated rotor field is trapezoidal or preferably at least approximately sinusoidal when the arrangement of the magnetic poles in a planar rotor surface is unwound. In this case, the axial pole width of the magnetic poles, d. H. the north and south poles each in the circumferential direction of the rotor, without the magnetic fields of the north and south poles cancel each other in the axial direction.

The invention is based on the consideration that an improved operating behavior of a permanent-magnet synchronous machine can be achieved if the mentioned parasitic effects can be reduced or avoided without any time delay. like other effects that negatively influence the operating behavior, in particular so-called axial tensile forces.

The disturbing effects are recognized to be caused or influenced by the geometric shape and / or the arrangement of the magnetic poles on or on the rotor surface. Thus, by means of a suitable design of the pole covering degree of the rotor, individual disturbing effects can be deliberately suppressed. Under the Polabdeckungsgrad this is understood as the percentage of the covered by the magnetic poles rotor surface.

Thus, for example, a pole coverage of the rotor surface with the magnetic poles of 80% leads to complete suppression of the fifth harmonic of the rotor field, while a pole coverage of 85.7% completely suppresses the seventh harmonic of the rotor field. The corresponding harmonics therefore do not appear in the rotor field and therefore can not cause any disturbances or disturbing effects.

It is recognized that a pole coverage of more than 85% does not lead to any substantial increase in the sinusoidal fundamental wave of the rotor field and thus of the actual useful field. In addition, considering the cost of the magnetic material, poly cladding levels less than 100% may be beneficial for economic reasons. However, comparatively low Polabdeckungsgrade lower the fundamental wave of the rotor field to an increased extent, resulting in a reduction in the utilization of the synchronous machine. Therefore, in order to influence the unwanted spurious effects, pole coverages in the range of 60% to 100%, preferably 60% to 95%, are particularly useful. It has also been found that a deliberate deviation of the geometry of the magnetic poles arranged on the rotor surface from the rectangular shape can already lead to a reduction or avoidance of at least individual disturbing effects. This is because certain geometric shapes of the magnetic poles can not only produce a trapezoidal, but even an at least approximately sinusoidal course of the axially averaged magnetic rotor field or the axially averaged magnetic rotor induction in the air gap. The axial averaging refers to the axial width of the magnetic poles extending in the direction of the rotor axis between their mutually opposite pole edges along the rotor axis.

As a result of this deviation of the geometric shape of the magnetic poles from the rectangular shape, a reduction of the parasitic effects is already achieved on account of the comparatively low-harmonic trapezoidal shape of the rotor field. A further reduction of the disturbing effects is achieved by an at least approximately sinusoidal rotor field.

Although this measure of the axial width of the magnetic poles changing in the circumferential direction of the rotor is also suitable for a so-called distributed winding of the stator, the stator preferably has a single-tooth winding, in particular in hybrid vehicle applications. In contrast to the distributed winding, each coil of a winding strand of the stator winding encloses only a single stator tooth in the single-tooth winding. This leads to comparatively small and compact winding heads and thus to very small axial lengths, which is particularly advantageous when used in Hybrid vehicles, especially since the electric Synchronous machine is integrated directly into the little space having powertrain.

In an advantageous embodiment, the arrangement of the magnetic poles and / or each magnetic pole on the rotor surface, ie. H. at its unwinding in a flat rotor or rotor surface, at least one axially or circumferentially aligned symmetry axis or symmetry. About the circumference of the runner, d. H. in the angular dimension between 0 ° and 360 ° or in the radian measure between 0 and 2π then takes place corresponding to the pole pair number periodic recurrence of changing in the circumferential direction of the rotor axial width of the magnetic poles.

Thus, different symmetrical geometries of the magnetic poles lead to the avoidance of axial force components or so-called axial tensile forces. Such, axially proportional to the torque increasing and also leading to additional bearing loads axial tensile forces arise in particular in the direction of the rotor axis beveled geometries of the magnetic poles. If the synchronous machine changes from motor to generator mode in such inclined geometries of the magnetic poles, the axial tensile forces also change direction. Correspondingly, torque ripples lead to axial alternating forces and to noises which are excited by corresponding axial vibrations. Such axial tensile forces can be avoided in a simple and effective manner if the varying axial width of the magnetic poles bounded by the two pole edges of the rotor shows certain symmetrical geometries in the circumferential direction.

According to an expedient variant, the or each magnetic pole has an axis symmetry to an axially, in particular centrally between the Polrändern extending in the circumferential direction Mirror axis on. Such an axisymmetric geometry, for example, show hexagonal and arrow-shaped magnetic poles or such arrangements of magnetic poles whose geometry corresponds to the enveloped surface shapes of two opposing sinusoidal boundary lines. This as well as said hexagonal geometry of the magnetic poles additionally shows an axial axis symmetry to a mirror axis running along the axial center line of the respective magnetic pole. Such an axial axial symmetry in turn show trapezoidal magnetic poles, which are distributed, for example comb-like offset from one another on the rotor surface.

Also, two adjacent magnetic poles to each other show an axis symmetry. This is again the case, for example, in the case of hexagonal magnetic poles, which form a cross slope in the overall arrangement in the region of the respective mirror axis between adjacent magnetic poles.

The varying in the circumferential direction of the rotor axial width of the magnetic poles includes in particular such geometries of

Magnetic poles, in which the axial width decreases towards the one pole edge, towards the opposite other pole edge or else, starting from a borderline between the pole edges, for example in the center, towards both pole edges.

Further variants and configurations of the magnetic poles and / or their arrangement on the rotor surface are the subject matter of the subclaims.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show: schematically in a cross section a four-pole

(2p = 4) permanent magnet synchronous machine with three-phase stator winding (single-tooth winding) and with a rotor with Magnetpole forming surface magnet, schematically the unwound in a plane rotor surface of the rotor of the synchronous machine according to FIG 1 with the formation of a chamfer gaplessly arranged trapezoidal magnetic poles, 3 shows a further variant of hexagonal magnetic poles according to FIG. 3, another variant of a trapezoidal pole arrangement according to FIG. 3 with fitted magnetic poles, in a representation according to FIG Arrangement with mutually rotated by 180 ° parallelogrammför- magnetic poles, in an induction radian diagram a trapezoidal course of the axially averaged rotor field of the arrangements of the magnetic poles according to FIG 2 to 7, in a representation acc ß 2 shows a lückenbehaf- ended array of trapezium-shaped magnetic poles, in a representation according to FIG 9 shows an arrangement of the magnetic poles with continuous afflicted Wechselschrägung, in a representation according to FIG 9 shows an arrangement of

Magnetic poles with gap-prone angled arrows, in an induction radian diagram according to FIG 8, the course of the rotor field of the arrangements of the magnetic poles according to FIG 9 to 11, FIG. 13 in a representation according to FIG. 2 sinusoidally rounded magnetic poles in a gap-covered sine pole arrangement, FIG.

8 shows a gap-shaped, sinusoidal profile of the axially averaged rotor field of the arrangements of the magnetic poles according to FIG. 13, FIG. 15 in an illustration according to FIG

Arrangement of sinusoidal magnetic poles (meandering pole arrangement),

16 shows a further gapless arrangement of sinusoidal

Magnetic poles (sine pole arrangement), FIG. 17 shows a variant of a gapless sine pole arrangement according to FIG. 16, FIG. 18 shows a further variant of a gapless sine pole arrangement according to FIG. 16, and FIG

19 in an induction radian diagram according to FIG. 14 the course of the rotor field of the arrangements of the magnetic poles according to FIGS. 15 to 19.

Corresponding parts are provided in all FIG with the same reference numerals.

The permanent magnet synchronous machine 1 shown schematically in cross-section in FIG. 1 has a stator 2 which, forming an air gap 3, has a rotor 4 with a rotor axis 4a extending axially and thus in the z-direction according to the illustrated coordinate system Magnet or rotor surface 4b radially spaced surrounds.

In the exemplary embodiment, the stator has six stator teeth 2 a and 6 stator slots 2 b into which individual teeth are wound. a three-phase rotating field winding with a corresponding assignment of the stator teeth 2a to the three star-connected winding strands U, V and W of the rotating field or stator winding is inserted. In this case, plus sign (+ U, + V, + W) means a (positive) current flowing out of the image or drawing plane, while a minus sign (-U, -V, -W) means a current flowing into the image or drawing plane ,

The rotor 4 is equipped with hereinafter referred to as surface magnets permanent or permanent magnet 5. These form magnetic poles which face the air gap 3 alternately with their north pole N or with their south pole S in the circumferential direction U of the rotor 4. In the exemplary embodiments, four magnetic poles in the form of two south magnetic poles S and two north magnetic poles N are arranged on or on the rotor surface 4b.

Each magnetic pole N, S may be in the form of a single magnet (single magnet). Such individual magnets, which each span a section or a portion of the rotor circumference, are also referred to as shell magnets. Alternatively, each magnetic pole N, S may be composed of many small magnetic plates arranged side by side on the rotor surface 4b.

Combinations of rectangular (rectangular) and triangular (triangular) magnetic plates are particularly suitable for the magnetic poles N, S according to the invention. In hybrid vehicle applications, rare-earth magnetic materials are preferably used. To suppress unwanted eddy current losses in these magnets, magnetic plates are preferable to the shell magnets. The permanent magnets 5 generate in the air gap 3 a rotor or rotor rotating field, also referred to as a field of excitation. When supplied with a three-phase sinusoidal alternating current, the stator winding U, V, W generates a circulating in the air gap 3 between the stator 2 and the rotor 4 magnetic field (stator or stator rotating field) with the number of poles of the rotor field corresponding number of poles (2p). This stator field also consists of alternating magnetic north poles N and south poles S, which rotate along the air gap 3. The number of poles (2p), which can be virtually arbitrary in the synchronous machine 1 according to the invention, is in the FIGS 1 to 19 2p = 4. The number of pole pairs of the illustrated four-pole, permanent-magnet synchronous machine 1 is therefore p = 2.

The runner or rotor rotating field generated by the rotor 4 has at the time considered on the machine upper side and on the machine underside of the synchronous machine 1 rotor south poles S, which are in accordance with the coordinate system shown in Figure 1 in the y direction opposite each other. At the intermediate machine sides, rotor north poles N are then obtained, which face each other in the x-direction. The four magnetic poles N, S, which are not concentrated on the sides of the machine, essentially span one pole pitch, which corresponds to a quarter circumference of the synchronous machine 1 in the present number of poles 2p = 4.

FIGS. 2 to 7 show the rotor surface 4b, which is developed in a plane, with magnetic poles N, S whose geometric configuration is angular, and whose arrangement on the rotor surface 4b is continuous with respect to the axially averaged rotor field. In the geometric configurations of the magnetic poles N, S and their arrangement on the rotor surface 4 shown in FIGS. 3 to 7, an axially averaged, trapezoidal rotor or air gap field L _{B is} generated along the circumference U of the rotor 4 according to the diagram illustrated in FIG , on the abscissa of the circumference U of the rotor 4 in radians and at its ordinate the induction B are removed. The rotor field L _B shows a trapezoidal, harmonic low field gradient.

In addition, in these embodiments, the axial width b of the magnetic poles N, S varies or changes in the circumferential direction U of the rotor 4. Further, in these embodiments, the magnetic poles N, S and / or their arrangement on the rotor surface 4b at least one axis symmetry.

In the case of the magnetic poles N, S which are trapezoidally shaped in FIG. 2 and lie practically without gaps in the circumferential direction U of the rotor 4, the pole coverage degree designated α is 100%. Spaced pole edges 7, 8 of the magnetic poles N, S define or define the axial width b of the pole dimension N, S extending in the z-direction. Mutually facing pole edges k of adjacent magnetic poles N, S run between the pole edges 7, 8 in the same direction obliquely, by adjacent trapezoidal magnetic poles N, S against each other by 180 ° twisted arranged on the rotor surface 4b and / or held.

This arrangement, referred to below as a change bevel, in which the axial width b of the magnetic poles N, S varies in the circumferential direction U of the rotor 4, sets one of magnetic poles N, S to magnetic poles S, N the direction or orientation Thus, the axial width b of the north poles N forming magnetic poles from the bottom in Figure 2 Polrand 8 to the upper pole edge 7 along the two pole edges k, while the axial width b of the south poles S forming magnetic poles along both pole edges k increases from the pole edge 8 to the pole edge 7 out.

Figures 3 to 5 show embodiments with hexagonal geometry of the magnetic poles N, S. In these, hereinafter referred to as cross-taper embodiments, the Polabdeckungsgrad α is less than 100% and α = 94% in the present embodiment. In the transition regions 9 between adjacent magnetic poles N, S, therefore, there remains a magnet-free region of the otherwise sheet-like packet-like material of the rotor 4.

While in the embodiment according to FIG. 2, each individual magnetic pole N, S shows axis symmetry with respect to a mirror axis A extending centrally in the z-direction, the overall arrangement of the magnetic poles N, S also shows an axial symmetry in the cross-skew according to FIG. Extending direction mirror axis A ^λ . All formed by the hexagonal geometry Polecken e of the magnetic poles N, S are on this common mirror axis A ^λ .

In the embodiment of FIG 4, the Polabdeckungsgrad α in turn, for example, 94%. However, in contrast to the embodiment according to FIG. 3, the pole corners e are not offset exactly in the middle between the two pole edges 7, 8, but towards the bottom edge 8. An offset of the pole corners e can also be provided towards the upper pole edge 7. Each individual magnetic pole N, S again shows an axis symmetry to the mirror axis A running in the z-direction. In the embodiment according to FIG. 5, in turn all magnetic poles N, S show an axis symmetry with respect to the pole-specific mirror axis A running in the z-direction. The pole corners e of the magnetic poles forming the south poles S are offset here towards the upper pole edge 7, while the pole corners e are the north poles N forming magnetic poles are offset to the lower pole edge 8 out. The Polabdeckungsgrad α is again 94% in this embodiment.

In the embodiment shown in FIG. 6 with trapezoidal, waisted magnetic poles N, S, these in turn have an axis symmetry both in the circumferential direction U to a mirror axis A ^λ common to all magnetic poles N, S and pole-specific axis symmetry to a mirror axis running centrally in the z direction A up.

In this embodiment, a further axis symmetry is given, in which the magnetic poles N, S is also given to a mirror axis A ^λλ extending in the boundary region between adjacent magnetic poles N, S in the z direction. Again, in this embodiment, the pole coverage α is 94%.

As well as the geometric configuration of the magnetic poles N, S of Figures 2 to 6 are also in the embodiment according to

FIG 7, the magnetic poles used N, S in turn angular. The geometric shape in this embodiment corresponds to that of a parallelogram. The north poles N and the south poles S forming magnetic poles with respect to the inclination of the pole edges k are each the same direction, but in the overall arrangement between adjacent magnetic poles N, S rotated by 180 ° and thus in opposite directions on the rotor surface 4b arranged. Also in this embodiment, the Polabdeckungsgrad α in turn, for example, 94%.

In the embodiment according to FIG. 7, in the arrangement of the magnetic poles N, S an axis symmetry is again given with respect to a mirror axis A ^λλ extending between adjacent magnetic poles N, S in the z-direction.

Already each of the axis symmetries shown in the embodiments of FIGS 2 to 7 ensures the avoidance of axial tensile forces, while each of the illustrated geometric configurations of the individual magnetic poles N, S due to their varying in the circumferential direction U axial width b of the rotor 4 unwanted disturbing effect, such as Drehmomentwellenigkei - Tent, cogging, power fluctuations and / or electrically excited noise avoids or at least reduced, which leads to an overall improved performance with high utilization of the synchronous machine 1.

In the embodiment shown in FIG. 9, the trapezoidal magnetic poles N, S, in turn, are arranged on the rotor surface 4b in gap-like alternating bevel. The resulting between adjacent magnetic poles N, S magnet-free gaps or transition regions 9 in this embodiment lead to a relatively low Polabdeckungsgrad, for example, α = 85%. With regard to the changing axial width b of the magnetic poles N, S in the direction of the circumference U of the rotor 4 and with respect to the axis symmetry of the individual magnetic poles N, S to these associated central or central, axially extending in the z-direction mirror axis A, this embodiment otherwise corresponds to that according to FIG. 2 The embodiment of FIG 10 corresponds with respect to the hexagonal geometry of the magnetic poles N, S and the axis symmetry along the axial mirror axis A and extending in the circumferential direction U central mirror axis A 'of the embodiment of FIG 3. However, this is a gap-prone cross bevel , which leads to a Polabdeckungsgrad α, for example, also 85%. The magnet-free transition regions 9 are comparatively large in this embodiment compared to that of FIG. Axis symmetries are shown in this embodiment along the mirror axes A, A 'and A''.

The embodiment according to FIG. 11 represents a so-called oblique arrow. For example, this arrow bevel is again filled with gaps, wherein the pole cover degree α in this embodiment is again 85%. The arrow bevel shows an axis symmetry which runs in the circumferential direction U of the rotor 4 and thereby along the axial pole width b centrally between the pole edges 7,8 of the magnetic poles N, S.

The course of the rotor field L _B common to the embodiments according to FIGS. 9 to 11 is shown in the diagram shown in FIG. 12, on whose abscissa the circumference U of the rotor 4 in radians and at its ordinate the induction B are plotted. The axially averaged rotor field L _B again shows a trapezoidal field profile. The field profile of the rotor field L _B according to FIG 12 shows in the zero crossings at π / 4, 3 / 4π and 5 / 4π each a slight offset of the trapezoidal half-waves. The reason for this disturbance of the rotor field L _B are the magnet-free gaps or transition regions 9 between adjacent magnetic poles N, S. However, the advantage of these embodiments is the comparatively low demand for magnetic material of the individual Magnetic poles N, S due to the relatively low Polabdeckungsgrades α.

In principle, in all the embodiments according to FIGS. 3 to 7 and 9 to 11 the pole cover degree α lying below 100% leads to a correspondingly reduced requirement for magnetic material for the magnetic poles N, S. On the other hand, geometric shapes of the magnetic poles N, S according to FIG and 9 and FIG 7 comparatively easy to produce. Common to all embodiments according to FIGS. 2 to 7 and 9 to 11 is a reliable suppression or reduction of the above-mentioned interference effects while at the same time avoiding undesired axial tensile forces.

In addition, the embodiments according to FIGS. 2 to 7 and FIGS. 9 to 11 show geometries or arrangements of the magnetic poles N, S respectively of a trapezoidal pole arrangement which result at least in part from specific or targeted combinations or subcombinations of other arrangements shown, whereby further geometries and / or Trapeze pole arrangements are conceivable.

The embodiments according to FIGS. 13 and 15 to 18 show rounded or rounded geometries of the magnetic poles N, S, which in their arrangement on the rotor surface 4b leads to a sinusoidal field profile of the rotor field L _B according to FIGS. 14 and 19. In this case, in the diagrams according to FIGS. 14 and 19, the circumference U of the rotor 4 is again plotted in radians against the axially averaged induction B (rotor field L _B ).

While in the case of a meander pole arrangement representing embodiment of FIG 15, the magnetic poles N, S itself a si- Nus-shaped geometry with each magnetic pole N, S having the geometry of a sine half-wave corresponds to the geometry of the magnetic poles N, S in the sine-pole arrangement representing embodiments of FIGS 13 and 16 of the enclosed by two opposing sine waves surface geometries.

13 and 16, the arrangements according to FIGS. 13 and 16 differ by a gap-like or gapless arrangement of the magnetic poles N, S on the rotor surface 4b. The embodiment according to FIG. 17 differs from that according to FIG. 16 in that the sine waves or sinusoidal waves enveloping the magnetic poles N, S are slightly distorted and / or offset from one another.

In the embodiment according to FIG. 18, each magnetic pole N, S is formed by two individual magnets each having the same pole orientation, the geometric shape of the magnetic poles N, S being at the vertex of a sine half-cycle or one

Part of such a lie together. The embodiment according to FIG. 18 again has an axis symmetry on a mirror axis A 'formed thereby, again centrally between the pole edges 7, 8 in the circumferential direction of the rotor 4. In addition, each individual magnetic pole N, S has an axis symmetry along a mirror axis A extending axially in the z-direction. A further axis symmetry exists along a mirror axis A ", which in turn extends axially in the z-direction between adjacent magnetic poles N, S.

In the embodiments according to FIGS. 15 and 16, the pole edges k of the magnetic poles N, S are partially or at least approximately completely matched to the sinusoidal shape. In the case of According to FIG. 17, the course of the pole edges k deviates slightly from the sinusoidal shape. The edge course of the pole edges k of the embodiments according to FIGS. 13 and 18 is semicircular or quarter-circle-shaped.

While the embodiments according to FIG. 15 have axis symmetries with respect to the pole-specific mirror axis A defined above, FIGS. 16 and 17 show an axis symmetry with respect to the previously defined mirror axis A ". The embodiment according to FIG. 16 also shows, like the embodiment according to FIG. 13, an axis symmetry to the previously defined mirror axis A '.

While in the embodiment of FIG 15, the Polabdeckungsgrad analogous to the embodiment of FIG 2 α = 100%, the Polabdeckungsgrad α in the embodiments of Figures 13 and 16 to 18 again analogous to the embodiments of Figures 3 to 7 and 9 to 11 less than 100%. Thus, the Polabdeckungsgrad α in the embodiment of FIG 16 even only 63.7%. In the embodiment according to FIG. 13, the pole cover degree α is even smaller than 63.7% due to the gapy sine pole arrangement shown there. The comparatively low pole coverage α of the embodiments shown in FIGS. 13 and 16 to 18 leads to a again comparatively low requirement of material for the magnetic poles N, S.

The advantage of the sine-pole arrangements according to FIGS. 13 and 15 to 18 is that, by means of a corresponding geometric configuration of the magnetic poles N, S and their arrangement on the rotor surface 4b, an at least approximately exactly sinusoidal axially averaged rotor field L _B or a sinusoidal axially averaged induction B is reached or generated. In addition, the axial width b of the magnetic poles N, S in the circumferential direction U of the rotor 4 also varies or changes in these sinusoidal pole arrangements according to the embodiments according to FIGS. 13 and 15 to 18. Further, in these embodiments, the magnetic poles N, S and / or their arrangement on the rotor surface 4b at least one axis symmetry.

Again, the embodiments of FIGS. 13 and 15 to 18 represent geometries or arrangements of the magnetic poles N, S in special sine or meander pole arrangements, which may result at least in part from specific or targeted combinations or subcombinations of other arrangements shown also other geometries or sine-pole arrangements are conceivable.

It is common to the embodiments according to FIGS. 2 to 7, 9 to 11, 13 and 15 to 18 that certain field components of the rotor field, ie specific harmonics, each cause certain of the mentioned interference effects, due to the special geometries of the magnetic poles N, S or additionally can also be avoided, reduced or completely eliminated by one or more of the axis symmetries A, A ', A''shown. Thus, it is recognized that virtually any desired, low-harmonic rotor field L _{B can be produced} solely by the geometry of the magnetic poles N, S and by special axis symmetries A, A ', A "on the basis of specific arrangements, in particular a sine pole arrangement or a trapezoidal pole arrangement, whereby field effects leading to disturbing effects are eliminated.

Claims

claims

1. Permanent-magnet synchronous machine (1) with a stator winding (U, V, W) for generating a stator field having stator (2) forming an air gap (3) a rotor (4) with a to a rotor axis (4a) radially surrounds a spaced-apart rotor surface (4b) on which in the circumferential direction (U) one of the number of poles (2p) corresponding number of magnetic poles (N, S) arranged with one of two opposite Polrändern (7,8) limited axial Polbreite (b) are, wherein the axial pole width (b) of the magnetic poles (N, S) varies in each case in the circumferential direction (U).

2. Permanent magnet synchronous machine (1) according to claim 1, wherein the arrangement of the magnetic poles (N, S) on the rotor surface (4b) shows at least one axis symmetry (A, A ^λ , A ^λλ ).

3. Permanent-magnet synchronous machine (1) according to claim 1 or 2, wherein adjacent magnetic poles (4b) to a in the direction of the rotor axis (4a) oriented mirror axis (A ^λλ ) are formed symmetrically.

4. Permanent magnet synchronous machine (1) according to one of claims 1 to 3, wherein each magnetic pole (N, S) on the rotor surface (4b) shows an axis symmetry (A).

5. Permanent magnet synchronous machine (1) according to claim 4, wherein each magnetic pole (N, S) symmetrical to a circumferential direction (U) of the rotor (4), preferably in the middle, between the pole edges (7,8) extending mirror axis (A ^λ ) is formed.

6. Permanent magnet synchronous machine (1) according to one of claims 1 to 5, wherein the axial pole width (b) of the magnetic poles (N, S) to the Polrändern (7,8) decreases towards.

7. Permanent-magnet synchronous machine (1) according to one of claims 1 to 6, wherein between the polar edges (7,8) extending pole edges (k) of each magnetic pole (N, S) are inclined in opposite directions to each other.

8. Permanent-magnet synchronous machine (1) according to claim 7, wherein the pole edges (k) of adjacent magnetic poles (N, S) extend in the same direction or in opposite directions obliquely.

9. Permanent-magnet synchronous machine (1) according to one of the preceding claims, wherein between the pole edges (7,8) the pole edges (k) of each magnetic pole (N, S) to each other in the same direction and the pole edges (k) of adjacent magnetic poles (N, S) to each other run obliquely in opposite directions.

10. Permanent magnet synchronous machine (1) according to one of claims 1 to 8, wherein the magnetic poles (N, S) have the shape of a hexagon.

11. Permanent magnet synchronous machine (1) according to any one of claims 1 to 9, wherein the axial pole width (b) of the magnetic poles (N, S) in the circumferential direction (U) varies sinusoidally.

12. Permanent magnet synchronous machine (1) according to claim 10 or 11, wherein the magnetic poles (N, S) in the circumferential direction (U) outer Polecken (s), which are arranged between the two pole edges (7,8).

13. Permanent magnet synchronous machine (1) according to any one of claims 1 to 12, wherein the magnetic poles (N, S) are composed of magnetic plates chen.

14. Permanent magnet synchronous machine (1) according to one of claims 1 to 13, wherein the Polabdeckungsgrad (α) of the arrangement of the magnetic poles (N, S) on the rotor surface (4b) is less than or equal to 100%, preferably 60% to 95% ,

15. Permanent magnet synchronous machine (1) according to one of claims 1 to 14, wherein the stator (2) has a single tooth winding.

16. Permanent magnet synchronous machine (1) according to any one of claims 1 to 15, wherein the axial pole width (b) of the magnetic poles (N, S) in the circumferential direction (U) varies such that the magnetic fields of the north pole (N) and the south pole (S) in the axial direction (z) do not cancel each other.

17. Hybrid vehicle with a permanent-magnet synchronous machine (1) according to one of claims 1 to 16.