WO2013131795A2

WO2013131795A2 - Rotor and electrical machine

Info

Publication number: WO2013131795A2
Application number: PCT/EP2013/053913
Authority: WO
Inventors: Gurakuq Dajaku
Original assignee: Feaam Gmbh
Priority date: 2012-03-05
Filing date: 2013-02-27
Publication date: 2013-09-12
Also published as: DE102012101822A1; WO2013131795A3

Abstract

The present invention specifies a rotor for an electrical machine, which rotor comprises two rotor elements (2, 3) which each comprise at least one flux barrier (4, 5, 4', 5'). The at least one flux barrier (4', 5') of the at least one second rotor element (3) is displaced in the circumferential direction in relation to the at least one flux barrier (4, 5) of the first rotor element (2). The two rotor elements (2, 3) are combined with one another axially and/or in the circumferential direction. The invention also describes an electrical machine having the rotor.

Description

description

Rotor and electric machine The present invention relates to a rotor for an electric machine. Furthermore, the invention relates to an electrical machine with such a rotor.

Electric machines include a stator and a rotor movable relative thereto. Depending on the relative movement, a distinction is made between rotating machines and linear machines. Electrical machines can work by motor or generator, converting electrical energy into rotational energy or translational energy, or vice versa.

For example, in synchronous machines with arranged in the rotor ^¬ th permanent magnet, but also in synchronous reluctance, a ripple of the torque of the machine may occur, which is normally undesirable. Such torque fluctuations ^¬ can be the cause of vibration, noise and speed fluctuations and cause problems in the control. For permanent-magnet synchronous machines, a distinction the torque ripple and the detent torque, while at the reluctance torque Wavy ^¬ ness is significant.

This torque ripple may result from the interaction between the magnetic flux due to stator currents and the magnetic flux of the rotor. In permanent magnet ^¬ magnet synchronous machines, the torque ripple is the result of the interaction between higher harmonics of the flux density of the air gap, the rotor magnet and the Stator current is generated. The cogging torque finally is He, as a variable reluctance consists ^¬ result of an interaction between the magnetic flux emanating from the magnet and the stator geometry depending on the angular position of the rotor.

The torque ripple and the cogging torque be less than 5% and 0.5% of the rated torque For example, in applications in the automotive industry sol ^¬ len. There have so far been described different approaches to adorn these unwanted cogging or torque ripple to redu ^¬. However, previously known approaches are usually associated with a reduced efficiency of the machine and / or higher manufacturing costs.

In the patent application DE 10 2010 032 764 a stator for an electrical machine is specified, which comprises at least two parts, which each have grooves for receiving electrical Wick ^¬ lungs. The slot openings of the two stators are shifted from each other in the circumferential direction. The stators are combined with each other axially and / or circumferentially. This approach leads to an effective reduction of the cogging torque of the electric machine, largely without the above-described disadvantages of hitherto known approaches. Here ER calls this approach a change in the geometry of the Sta ^¬ tors.

Object of the present invention is to provide a rotor and a machine with this rotor, in which the torque ripple Well is significantly reduced. The object is achieved with the objects of the independent claims. Advantageous embodiments and wide Erbil ^¬ compounds are indicated in the dependent claims. In one embodiment, the rotor for an electric machine comprises a first and a second sub-rotor. These each have at least one magnet and at least ei ^¬ ne associated with the magnet flux barrier. The flux barrier is designed to inhibit the magnetic flux in the rotor. The flow barrier of the at least one two ^¬ th ^sub -rotor is arranged shifted with respect to the at least one flow barrier of the first sub-rotor in the circumferential direction of the rotor. The two sub-rotors are combined with each other in the axial direction and / or in the circumferential direction.

An asymmetrical displacement of the flow barriers in the sub-rotors relative to one another correspondingly results in a relative shift of the location of the minimum reluctance of the sub-rotors. This in turn results in a relative displacement of the torque ripple components generated by the respective sub-rotors. Combining the sub-rotors as proposed, the torque ripple can the partial rotors are mutually compensated and the total torque ripple of the ^¬-like rotor can be significantly reduced, to a cancellation.

The flow barriers of the rotor can be designed, for example, as air-filled cavities of the rotor.

Preferably, the flow barriers directly adjoin the magnets in the circumferential direction on opposite sides. Displacement, in one embodiment, means that a flux barrier that attaches to a magnet is expanded in the circumferential direction, that is, enlarged, while the opposite flux barrier on this magnet can be reduced by the corresponding amount.

As indicated above, the displacement of the flux barriers relative to one another is designed such that the minimum of the reluctance of the rotor is shifted relative to one another, that is to say in comparison with the two sub-rotors.

Rotors of electric machines can be described with the d-q-axis theory. The d-axis lies in the middle of a rotor pole, and the q-axis lies between two rotor poles. The q-axis is shifted by 90 ° with respect to the d-axis.

In permanent magnet excited machines, for example with inserted or with buried magnets in the rotor, the d-axis represents the location with the highest reluctance and the q-axis the place with the lowest reluctance.

In synchronous reluctance machines, too, the d-axis represents the region of highest reluctance and the q-axis represents the region of least reluctance.

As discussed above, circumferential flow barriers asymmetrically shifted to the right or left will cause the minimum reluctance area of the rotor to also shift to the left and right circumferentially, respectively. Flow barriers are preferably regions of non-magnetic and non-electrical material, such as air. You can, for example, as a cavity in the Rotor laminated core be realized. This cavity borders be ^¬ vorzugt of the magnet and is enclosed by the way the iron of the Ro ^¬ tors. In the dq-axis theory, the described Ver ^¬ shift the range of minimum reluctance of the rotor acts out so that the q-axis is also displaced and located in the middle of the minimum of the range of minimum reluctance rotor. In other words, the asymmetric displacement of the flux barriers causes the q-axis to be ^shifted by an angle.

It is proposed to disassemble the rotor into at least two sub-rotors, wherein in one rotor the q-axis is shifted to the right by a certain angle and to the left by a certain angle to the other rotor. Instead of the terms right and left, the terms clockwise and counterclockwise can alternatively be used. Since with the displacement of the q-axis in each case a shift of the components of the torque ripple of the sub-rotors is accompanied, it is possible in this way, the ge ^¬ total torque ripple of the rotor significantly re ^¬ ducieren, up to an extinction of these Residual ripple components of the torque.

In one embodiment, the shift angles of the q-axes of the sub-rotors are equal in magnitude to a rotor with conventional flux-barriers, but have a different sign.

In one embodiment, the sub-rotors each have at least one magnetic north pole and a magnetic South Pole on. The north pole and the south pole per each have ge ^¬ genüberliegende flux barrier, wherein the gegenüberlie ^¬ constricting flow barrier of the North Pole, as well as the south pole with respect to a respective axis of symmetry of a conventional rotor are designed asymmetrically.

Partial rotors are preferably combined with each other, which apart from the described asymmetric displacement of the flow barriers have the same structure, in particular the same rotor geometry. When the sub-rotors are combined in the axial direction, the sub-rotors may even have a completely identical structure, but are not axially combined in the same sense, but one of the sub-rotors is combined in the opposite direction with the other.

Preferably, the first and the second part rotor, in the embodiment with permanent magnets, at least one of the following types: magnets used in grooves, buried magnets, such as buried tangential magnets or buried V magnets, or a buried Mehrschichtstruk ^{¬ structure} . Preferably cuboid magnets are used.

Alternatively or additionally, the rotor may be designed as a reluctance rotor, in which case the first and second part-rotors are also designed as reluctance rotors.

In another embodiment, an electric machine is provided with a stator and a rotor described above. The stator may be designed to receive electrical windings, for example in stator slots. In this case, the stator for receiving a three-phase electrical Be provided system, but there are other current systems ^¬ me possible.

The invention will be explained in more detail by means of several exemplary embodiments with reference to drawings.

Showing:

1 shows an embodiment of an electrical machine with a first part rotor according to the proposed principle,

FIG. 2 shows an exemplary embodiment of an electrical machine with a second partial rotor according to the proposed principle,

FIG. 3 shows an embodiment of a rotor in which the first and second part-rotors according to FIGS. 1 and 2 are combined axially with one another,

Figure 4 shows a conventional rotor with V-shaped buried

magnets

Figures 5A and 5B embodiments of the magnetic

Flow lines of respective sections of the examples of Figures 1 and 2,

FIG. 6 shows an example of a diagram of torque ^profiles ,

Figures 7A and 7B embodiments of two partial rotors with buried tangential magnets according to the proposed principle, and 8A and 8B are exemplary embodiments of two embodied as Reluk ^¬ dance rotor part-rotors according to the principle proposed.

1 shows an embodiment of an ^electrical machine having a stator 1 and a rotor, wherein a first portion rotor 2 is shown in FIG. 1 The first part rotor 2 has buried V-shaped arranged magnetic poles, which are formed as north pole N and south pole S. Insge ^¬ velvet are two magnetic pole pairs, that is a total of four buried magnets S, N provided, opposite magnets are each of the same polarity. At the respective opposite ends of the legs of the V-shaped magnets is followed in each case by a flux barrier 4, 5, which is realized as an air-filled cavity. In each case in the clockwise circumferential direction of the respective magnetic S, N, starting the magnetic flux barrier 5 increases, currency ^¬ rend the flow barrier Neten 4 counterclockwise from the starting Mag- is reduced. This results in an un ^¬ symmetrical distribution of the flux barriers 4, 5 at the respective buried V-shaped magnet S, N.

In other words, the flux barrier 4, 5 respectively cavities in the iron core of the rotor which adjoin the permanent magnets ^¬ S, N are.

If the electrical machine is viewed in a dq-axis representation with a d-axis and a q-axis perpendicular to it in an electrical angle, the d-axis passes through the center of a rotor pole N, while the q-axis is electrically perpendicular to it and in the middle between the north pole N and an adjacent south pole S runs. by virtue of the fact that in the example two pairs of poles are provided, the geometric angle is not 90 °, but only half of it, namely 45 ° between the d-axis and q-axis. At the same time, the d-axis represents the region of maximum reluctance of the rotor, while the q-axis represents the region of least reluctance. This ideal angle of 45 ° applies to symmet ^¬-driven arrangement of the flux barrier, as shown later in FIG. 4 In the present Figure 1, however, there is a shift of the q-axis by an angle _r clockwise. This is due to the displacement of the area ge ^¬ ringster reluctance in the rotor by the same angle _r due to the asymmetry of the flux barrier. 4, 5

FIG. 2 shows an electric machine with a second partial rotor 3 on an exemplary embodiment. The structure and the geometry of the two sub-rotors of Figures 1 and 2 are completely identical, except for the asymmetry of the flux barriers, which are not clockwise in Figure 2, but in the counterclockwise direction. This results in the example of Figure 2, a displacement of the q-axis counterclockwise, by an angle _r . The displacement angle _r of the examples of Figures 1 and 2 is moderate be ^¬ supporting the same, but in opposite directions. If the partial rotors 2, 3 according to FIGS. 1 and 2 are combined axially one after the other to form a common rotor, the result is a rotor according to the embodiment of FIG. 3. Here, the second partial rotor 3 according to FIG. 2 is behind the first part Rotor shown in FIG. The stator 1 is not shown in the illustration of Figure 3 for the sake of clarity. It can be seen that the resulting q-axis of the entire rotor of Figure 3, which is characterized by superposition of the q-axis ql of the first part of the rotor 2 and the q-axis q2 of the second sub-rotor 3 results, just again at an angle of electrically 90 ° to the d-axis of the Ge ^¬ samtrotors. The d-axis of the overall rotor is identical to the dl-axis of the first sub-rotor and the d2-axis of the second sub-rotor. Function and advantages of this ^{Ausgestal ¬} tion will be explained later with reference to Figure 6.

Figure 4 shows a conventional rotor with V-shaped buried magnets S, N and symmetrically at the outer

Limb ends adjoining flow barriers.

It can be seen that in the case of the conventional rotor of FIG. 4 the same angle exists between the d-axis and the q-axis as in the combination of partial rotors with circumferentially displaced flow barriers according to FIG.

Figures 5A and 5B show the field curves for the magneti ^¬ rule flux in the rotor and stator, wherein Figure 5A 5B is an exemplary detail of Figure 1 and Figure is an exemplary detail of FIG 2 with respect to the rotor and Statorgeo ^¬ geometry. One clearly recognizes the effect of the respective lo ^¬ cal enlarged flow barriers 5, 5 ', which locally reduce the magnetic flux significantly. This effect ultimately results in the shift of the region of minimum reluctance, which can be illustrated by the respective displacement of the q-axis by an angle _r .

The effect of the combination of the partial rotors according to FIG. 3 will be clear from the graph of FIG. In Schau- image of Figure 6 is T ge ^¬ shows the electromagnetic torque, the torque is plotted against the Rotorpo ^¬ sition in electrical degrees. The curve marked X denotes the torque curve of the electric machine of Figure 1, when the rotor is formed only from the first part of rotor 2, while the torque curve denoted by 0 represents the torque of the machine when the rotor is formed only with the second part of the rotor 3 of Figure 2. It can be seen that each of these torque curves X, 0 taken by itself has a high torque ripple.

The resulting torque curve - is drawn in dashed lines ^¬ and applies to the overall arrangement of Figure 3. In this case, the total rotor is half formed from the sub-rotors 2 and 3. It can be clearly seen that the total torque ripple is very clearly reduced in the circumferential direction as a result of the proposed combination of partial rotors 2, 3 with flow barriers displaced relative to one another in the circumferential direction. This is accompanied by a significant reduction in the

Consequences of a high torque ripple, for example, ^¬ a significant reduction of vibrations of the electric machine during operation and the operating noise and ultimately a significant improvement in efficiency.

Thus, the electrical machine described in ^¬ example, especially for the automotive sector.

FIGS. 7A and 7B show a further embodiment of the proposed principle with buried, tangential permanent magnets based on respective examples of two partial rotors. The embodiment is based in its structure, the function ^{¬ way} and the advantageous mode of action on that ge ^¬ according to the figures 1 to 3 and will not be described in this respect again. Here, however, instead of the V-shaped magnets are introduced in a tangential design in the sub-rotors. The tangential magnets S, N in turn are followed by flux barriers 4, 4 ', 5, 5', wherein these in the 7A and 7B are again shifted in different directions of rotation, so that the asymmetry already explained above with the corresponding axial displacement of the q-axes of the partial rotors ql, q2 results. These sub-rotors according to FIGS. 7A and 7B can in turn be combined axially with each other to form an overall rotor having the advantages explained above and a reduced torque ripple. Figures 8A and 8B show partial rotors according to an application of the proposed principle to a pure reluctance rotor without permanent magnets. The provided with a conventional Reluk ^¬ tanzrotor doubly v-shaped introduced areas with missing iron, that is, air, go into unbalanced flow barriers at the respective ends of the V-shaped areas. This asymmetry in the circumferential direction results in the first part rotor according to Figure 8A again a shift of the q-axis clockwise to the axis ql, while in the second part rotor of Figure 8B a shift in the counterclockwise direction, again by the same

Angular amount, is provided so that the new q-axis q2 results.

These sub-rotors according to FIGS. 8A and 8B can in turn be combined axially with one another to form an overall rotor having the advantages explained above and a reduced torque ripple.

The electrical machine described requires no changes to the stator. It is sufficient to carry out the measures described in the rotor. The asymmetrical design of the flux barriers 4, 5 can be done in a simple manner by punching the laminated core of the rotor, wherein for the realization 3, only a single punching tool is required, since the rotors of FIGS. 1 and 2 can be manufactured very inexpensively by turning over the laminations and twisting axially combined according to FIG.

Of course, it is within the scope of expert action, instead of the axial combination shown to make a combination of part-rotors in the circumferential direction, for example, with two part rotors, each of which geomet ^¬ cover 180 ° and can be realized as a half cylinder.

Similarly, it is within the skill of the art to use, instead of the buried V-shaped permanent magnets or buried tangential magnets shown, other rotor topologies, such as magnets inserted in grooves or buried multilayer magnets. Moreover, the proposed principle is not limited to buried Permanentmag ^¬ designated, but, for example, schichtreluktanzrotortopologien even with multi advantageously be used.

Reference sign list

1 stator

2 first part rotor

3 second part rotor

4 reduced river barrier

4 'reduced river barrier

5 enlarged river barrier

5 'enlarged flux barrier d d axis

dl axis

d2 axis

q q axis

ql axis

q2 axis

North pole

S south pole

r Displacement angle of the q-axis

Claims

Rotor for an electrical machine, the rotor ^comprising :

- a first part rotor (2) and at least one

second partial rotor (3), each of which comprises at least one flow barrier (4, 4', 5, 5'),

- wherein the at least one flow barrier (4', 5') of the at least one second partial rotor (3) is displaced in the circumferential direction with respect to the at least one flow barrier (4, 5) of the first partial rotor (2). is and

- The two partial rotors (2, 3) axially with each other

and/or are combined in the circumferential direction.

Rotor according to claim 1,

characterized in that

the displacement of the at least one flow barrier (4', 5') of the at least one second partial rotor (3) with respect to the at least one flow barrier (4, 5) of the first partial rotor (2) is designed in such a way that a minimum of the rotor reluctance of the second partial rotor (3) is shifted relative to a minimum of the rotor reluctance of the first partial rotor (2).

Rotor according to claim 1 or 2,

characterized in that

the displacement of the at least one flow barrier (4 ', 5') of the at least one second part-rotor (3) with respect to the at least one flow barrier (4, 5) of the first part-rotor (2) is designed in this way that the q-axis (q2) of the second part-rotor (3) is shifted relative to the q-axis (ql) of the first part-rotor (2), each based on a common d-axis (d). Rotor according to one of claims 1 to 3

characterized in that

the first part rotor

(2) and the at least one second partial rotor (3) each comprise at least one magnet (S, N), to which the at least one flux barrier (4, 4', 5, 5') of the first or at least one ^magnet is attached is assigned to a second partial rotor (2, 3). 5. Rotor according to claim 4,

characterized in that

- the first and second part rotors (2,

3) each comprise at least one magnetic north pole (N) and one magnetic south pole (S), each of which has an axis ^of symmetry,

- the north pole and the south pole each have opposing river barriers (4, 4', 5, 5'),

- wherein the opposite flow barriers (4, 4 ', 5, 5') of the north pole (N) are designed asymmetrically with respect to its axis of symmetry and / or

- whereby the opposite river barriers (4,

4', 5,

5') of the south pole (S) are designed asymmetrically with respect to its axis of symmetry.

6. Rotor according to one of claims 1 to 3,

characterized in that

the first and second partial rotors (2, 3) are each designed as a reluctance rotor.

7. Rotor according to one of claims 1 to 6,

in which the at least one flow barrier (4 ', 5') of the at least one second part-rotor (3) with respect to the at least one flux barrier (4, 5) of the first partial rotor (2) is displaced in the circumferential direction in such a way that the torque ripple of the partial rotors is ^mutually compensated and/or the torque ripple is reduced.

8. Rotor according to one of claims 1 to 7,

in which the at least two partial rotors (2, 3), ^apart from the displacement of the flow barriers (4, 4', 5, 5'), have the same structure, in particular the same geometry.

9. Rotor according to one of claims 1 to 8,

characterized in that

the first and second partial rotors (2, 3) have permanent ^magnets which are of at least one of the following types:

- magnets inserted in grooves,

- buried tangential magnets,

- buried V magnets,

- buried multi-layer structure.

10. Electric machine with a rotor according to one of the

Claims 1 to 9 and further comprising:

a stator (1), the rotor (2, 3) relative to

Stator is movable.