EP3513483A1

EP3513483A1 - Segment magnet and permanent magnet motor comprising segment magnets

Info

Publication number: EP3513483A1
Application number: EP17784918.9A
Authority: EP
Inventors: Elmar Hoppach; Sunny Zhang
Original assignee: Brose Fahrzeugteile SE and Co KG
Current assignee: Brose Fahrzeugteile SE and Co KG
Priority date: 2016-10-06
Filing date: 2017-10-04
Publication date: 2019-07-24
Also published as: WO2018065455A1; CN109891710A; DE102016219395A1; JP2019530421A; CN109891710B

Abstract

The invention relates to an optimized segment magnet for a permanent magnet motor. By establishing a magnetization profile within the segment magnet in accordance with a continuous cyclic function, optimized operating characteristics for the electric motor can be achieved with a reduced use of material. The cyclic formation of the magnetization direction in the segment magnet can also be combined with shaping in accordance with a further cyclic function, in order to intensify this effect further.

Description

Segment magnet and permanent magnet motor with segment magnets

The present invention relates to a segment magnet, in particular a segment magnet for a permanent magnet ^¬ motor, and a permanent magnet with segment magnets.

State of the art

The course of the magnetic field in an air gap ei ^¬ nes electric motor between the rotor and stator influenced in a decisive way the performance of the engine. In particular, is affected by the variation of the magnetic field, the Leis ^¬ tung dense, the torque uniformity and Ge ^¬ the noise levels of the engine. It is the goal of a permanent magnetic excitation of the magnetic field in the air gap to maximize the flux fundamental while minimizing interfering upper fields.

Magnetic segments with radial and parallel magnetization are known for permanently excited electric motors. The increase in the flux density at the edges of the magnets crying, ^¬ more than an increase in power density non-uniform moment forth, which is connected to a noise. This effect is particularly pronounced at radially magnetized Magnetseg ^¬ elements, wherein opposite paral lel magnetized magnet ^¬ a higher flux linkage can be achieved in this case.

To improve the noise development in the engine, the edges of the magnet segments are variously beveled. This leads to a reduction of the magnetic flux density. As a result, the utilization of the refrigerator to favor ^¬ a lower noise emission decreases. In addition to a purely parallel and radial magnetization of the magnet segments, a variety of courses for the magnetic flux can be realized in recent times. A possible course is described, for example, by the so-called Halbach structure. Here, a magnet array of several sub-segments of permanent magnets is assembled, the magnetization direction is tilted against each other by 90 ° in the direction of a longitudinal axis. The field lines move closer together on one side, while on the opposite side the field lines are farther apart and the magnetic field is weakened.

Although conventional methods can reduce the noise of a motor, which usually leads to a poorer utilization of the magnetic material used.

There is therefore a need for a permanent-magnet segment magnets for electric motor, which allows an optimized utilization of the magnetic material at the same time improved Be ^¬ operating characteristics, such as reduced noise. In particular, there is a need for segment magnets which can be parameterized as freely as possible, the parameterization of which can be supplied both to a field calculation in the design of the electric motor and to the required manufacturing method for the corresponding segment magnet.

Disclosure of the invention

The present invention, in one aspect, provides a segment magnet for a permanent magnet motor. The segment magnet is characterized in that a magnetization vector of the segment magnet ^¬ along an outer edge of the Seg ment ^¬ magnets having an angle-dependent direction. This angle-dependent direction is described here by a continuous, cyclic function.

According to a further aspect, the present OF INVENTION ^¬ dung relates to a permanent magnet motor. The permanent magnet motor comprises a stator and a rotor rotatably mounted on the stator. Rotor or stator comprise a magnet with multiple magnetic poles. In particular, the magnet of the rotor or stator includes several inventive segment Magne ^¬ te.

Advantages of the invention

The present invention is based on the recognition that conventional segment magnets, as they are widely used in permanent magnet motors, due to constructive measures to minimize the noise in general, the magnetic material used can exploit only Unzu ^¬ reaching. In particular, constructive measures ^{¬ taken} , such as the bevel of the edges of the magnet lead to a reduced magnetic flux density.

The present invention is therefore based on the idea to take this finding into account and provide a Segmentmag ^¬ net for a permanent-magnet electric motor, in addition to optimized operating characteristics, such as a reduced noise, improved utilization of the required magnetic material and thus a high magnetic flux density in relation to allows the used magnetic material. Further, the present invention provides a segment magnet whose Para ^¬ metrization be described mathematically. In this way, the parameters of the segment magnet can be easily supplied to a field calculation, for example, for the development or construction of electric motors, and moreover, the parameters of such a segment magnet can also be easily fed to a manufacturing process. As a result, both time and cost advantages can be realized.

The angle-dependent variation of the magnetization vector according to a continuous cyclic function allows a suitable parameterization of the direction of the magnetization vector.

In particular, by an angle-dependent orientation of the magnetization vector, the magnetization direction can be well adapted to the contour of a motor housing.

According to one embodiment, the cyclic function for describing the direction of the magnetization vector along the outer curve of the segment magnet comprises a sum of a plurality of cyclic terms. Cyclic terms are special ^¬ periodic functions, such as a sine or cosine function.

According to one embodiment, the cyclic function for describing the direction v (φ) of the magnetization vector along the outer edge of the segment magnet is formed according to the following formula: n

ν (φ) = ^ _fc s (pk <p)

k = l

In this case, the angle of a radius vector with respect to a predetermined direction is described by φ. ν (φ) represents the angle of the direction of the magnetization vector towards ^¬ above the respective radius vector. p corresponds to the number of pole pairs to be realized permanent magnet motor, n is an integer modeling degrees for the Magneti ^¬ sierungsvektor on. ak are the modeling coefficients of the magnetization vector. The above-described formula thereby describes a Fourier representation of the direction of the magnetization vector along the outer edge of the Seg ment ^¬ magnets.

According to one embodiment, the first modeling ^¬ coefficient ai an angular range between 10 degrees and 50

Degrees. The other modeling coefficients a2 to a _n are preferably smaller than the first Modellie ^¬ approximately coefficient ai. By such a parameterization of the segment magnet segment magnets are achieved with very good operating characteristics with optimized utilization of the magnetic material used.

In one embodiment, an outer edge of the Seg ment ^¬ magnet on an angle-dependent outer radius. The angle-dependent outer radius is described by a further cyclic function. By forming an angle-dependent direction of the magnetization vector and simultaneously adapting the outer edge of the segment magnet according to cyclic functions, the direction of the Magnetization vector and outer edge are optimally matched.

According to one embodiment, the further cyclic function for describing the radius for the outer edge of the segment magnet comprises a sum of a plurality of cyclic terms. Cyclic Terme include, as already explained above, the special ^¬ periodic functions, such as a sine function or a cosine function.

According to one embodiment, the further cyclic function for describing the radius R (cp) of the outer edge for the segment magnet is formed according to the following formula: m

d ₀ T ¹

R (<p = y + _, ^h k ^sin (P ^k Ψ)

k = l

In this case, φ describes an angle of the radius vector with respect to a given direction. R (cp) represents the angle-dependent function of the radius of the outer edge of the segment Magne ^¬ th. P indicates the number of pole pairs of the permanent magnet motor, for which the segment magnets are used sol ^¬ len, m defining an integer modeling degree of

Radius function, bk are the modeling coefficients of

Radius function, do indicates an inner diameter of a pole pot of the permanent magnet motor. The formula described above describes a Fourier representation for the development of the shape of the outer edge of the segment magnet.

According to one embodiment, the first modeling ^¬ coefficient bi of the radius function in a range of values from 0.03 to 0.12. In addition, the others can Modeling coefficients b2 to b _m the radius function preferably be smaller than the selected first Modellie ^¬ coefficient approximately the radius function.

The above embodiments and developments can, as far as appropriate, combine arbitrarily. Further embodiments, further developments and implementations of the invention include not explicitly mentioned COMBINATION ^¬ NEN previously or hereinafter described with respect to the embodiments, features of the invention. In particular, the expert will thereby also add individual aspects as verb ^¬ serungen or supplements to the respective basic forms of the present invention.

Brief description of the drawings

The present invention will be explained in more detail with reference to the exemplary embodiments indicated in the schematic figures of the drawings. Showing:

1 shows a schematic representation of a cross section through a permanent magnet motor with segment magnets according to an embodiment;

Figure 2 is a schematic representation of a cross section through a segment magnet according to an embodiment; and

Figure 3 is a schematic representation of a field curve for a magnetic field in a permanent magnet motor with ^¬ segment magnets according to an embodiment. 1 shows a schematic representation of a Perma ^¬ nentmagnetmotors according to an embodiment. The Perma ^¬ nentmagnetmotor comprises a housing 2 are arranged at the four segment magnets. 1 These four segment magnets 1 bil ^¬ here the stator of the motor. Further, the permanent magnet motor 2 comprises a rotatable rotor 3. In the embodiment shown here is a four-pole motor. However, the following description of a four-pole motor is for illustrative purposes only and does not limit the present invention to a predetermined number of poles.

The facing in the direction of the rotor 3 inside of Seg ^¬ ment magnets 1 has an at least approximately circular surface, so that each segment magnet 1 in the direction of the rotor 3, the surface of a cylinder segment.

The shape of the facing in the direction of the housing outside of the segments 1 is formed in accordance with a steady cyclic function ^¬ cally. This steady cyclical radio ^¬ tion is explained below in more detail. In particular, the housing 2 is adapted to the housing 2 facing side of the segment magnets 1.

In the case of the cyclic function which describes the outer side of the segment magnets 1 facing the housing 2, it can be, in particular, a shape which according to a Fourier representation can be described as the sum of a plurality of cyclic terms. The configuration of this Fourier representation will be described below with reference to FIG. In this case, the distance R (cp) of the outer edge of the housing 2 side facing the segment magnet 1 to a center of the motor according to the following formula be written ^¬ m

d ₀ T ¹

R (<p = y + _, ^h k ^sin (P ^k Ψ)

k = l

In this case, the angle φ describes the angle between a current radius vector and a center axis of the segment magnet 1 shown in dashed lines in FIG. 2. The number of pole pairs of the motor is described by d, d0 describes the inside diameter of a pole pot of the motor to be realized. The coefficients bk represent Modellierungskoeffi ^¬ coefficient represents the radius function R (cp), which describes the the housing 2 of the engine-facing side of the segment magnets. 1 The upper limit m of the summation function represents the degree of modeling. As a rule, a ^single- digit modeling degree of, for example, three, four or five coefficients is sufficient here. In addition, however, any higher modeling levels are possible.

The first modeling coefficient bi may preferably be in

Range between 0.03 and 0.12 are chosen. In particular, values of 0.05, 0.07 or 0.1, for example, are suitable for a first modeling coefficient bi. The others

Modeling coefficients b2 to b _m generally indicate

Values which are smaller than the values of the first one

Modeling coefficients b_. For example, the

Modeling coefficients with increasing atomic number a decreasing value. In addition to the previously described shaping of the segment magnets 1, the direction of the magnetization vector in the segment magnets can also be represented by a cyclic function, in particular by a Fourier series. The here asked before ^¬ magnetization direction of the segment magnets 1 differs from conventional doing magnetization ^¬ insurance forms, such as a radial, parallel or Halbach magnetization.

Figure 3 shows a schematic representation of a Magneti ^¬ tion of a magnetic circuit using the example of a four-pole motor. The direction ν (φ) of the magnetization vector ent ^¬ long an outer edge of the segment magnet 1 can be ^¬ example described according to the following formula: n

ν (φ) = ^ _fc s (pk <p)

k = l

Here φ describes the angle of the radius vector. The ^¬ Rich processing of the magnetization vector in relation to the Radiusvek ^¬ gate is described by ν (φ). Analogously to the description of the outer geometry of the segment magnet 1, here too, p represents the number of pole pairs of the electric motor

Modeling coefficients for the direction of the magnetization vector described, and n represents the Modellierungs ^¬ degree for the direction of the magnetization vector.

For a suitable design of the direction of magnetization in the segment magnet 1, the first model ^¬ lierungskoeffizient ai, for example, a value between 10 degrees and 50

Have degree. For example, values of 20 degrees, 30 degrees or 45 degrees are possible. The other modeling features As a rule, coefficients a2 to a _n can be chosen to be smaller than the first modeling coefficient ai. In ^¬ game example, it is possible that the Modellierungskoeffi ^¬ coefficients each having smaller values with increasing atomic number.

By the formation of a segment magnet 1 with the above-described external geometry and magnetization direction of the segment magnets may be formed of a permanent-magnet electric motor which can be achieved with a reduced use of materials for the magnetic material optimized Betriebsei ^¬ properties for an electric motor. In particular, for example, the running properties, such as the noise, can be improved.

By combining an external geometry in the form of a cyclic function and simultaneously adjusting the direction of the magnetization vector according to a further cyclic function, optimized properties can be achieved. In addition, however, it is also possible to form only the direction of the magnetization vector in the form of a cyclic function, while for the outer geometry of the segment magnet conventional form to currency ^¬ len. In this case, an optimization of the segment magnets 1 can be achieved even with a conventional shaping by the configuration of the direction for the magnetization vector. Due to the remaining conventional shape such optimized segment magnets 1 can be installed in existing engine geometry. Here ^¬ by optimized operating characteristics can be achieved even for existing engine geometries. In summary, the present invention relates to an optimized segment magnet for a permanent magnet motor. By setting a magnetization curve intra ^¬ half of the segment magnet according to a continuous cyclic function can be achieved with reduced use of material-optimized operating characteristics for the electric motor. The cyclic formation of the direction of magnetization in the segment magnet can moreover be combined with a shaping according to a further cyclic function in order to further enhance this effect.

Claims

claims

Segment magnet (1) for a permanent magnet motor, wherein a magnetization vector of the segment magnet (1) along an outer edge (10) of the segment magnet (1) has an angle-dependent direction according to a continuous cyclic function.

The segment magnet (1) of claim 1, wherein the cyclic function of the direction of the magnetization vector comprises a sum of multiple cyclic terms.

Segment magnet (1) according to claim 1 or 2, wherein the cyclic function of the direction of the magnetization ^¬ vector is formed according to the following formula: n

ν (φ) = ^ _fc s (pk <p)

k = l

With :

φ: angle of a radius vector,

v (φ): angle of the magnetization vector with respect to

Radius vector,

p: pole pair number of the electric motor,

n: integer modeling degree of magnetization approximately ^¬ vector, and

ak: modeling coefficients of the magnetization vector ^¬;

Segment magnet (1) according to claim 3, wherein the first Mo ^¬ dellierungskoeffizient ai has a value range between 10 degrees and 50 degrees. Segment magnet (1) according to claim 4, wherein the further modeling coefficients a2 - a _{n are} smaller than the first modeling coefficient ai.

Segment magnet (1) according to one of claims 1 to 5, wherein an outer edge (10) of the segment magnet (1) ei ^¬ NEN angle-dependent outer radius according to another cyclic function.

7. segment magnet (1) according to claim 6, wherein the further cyclic function for the radius of the segment magnet (1) comprises a sum of a plurality of cyclic terms.

8. segment magnet (1) according to claim 6 or 7, wherein the further cyclic function for the radius of an outer edge (10) of the segment magnet (1) is formed according to the following formula: m

d ₀ T ¹

R (<p = y + _, ^h k ^sin (P ^k Ψ)

k = l with:

φ: angle of the radius vector,

R ((p): angle dependent function of the radius of the

Outer edge of the segment magnet,

p: pole pair number of the electric motor,

m: integer modeling degree of

Radius function,

bk: modeling coefficients of the radius function, do: inside diameter of a pole pot of the Perma ^¬ nentmagnetmotors.

9. Segment magnet (1) according to claim 8, wherein the first bi Mo ^¬ the radius function has dellierungskoeffizient a range of values from 0.03 to 0.12.

10. segment magnet (1) according to claim 9, wherein the further modeling coefficients b2 - b _{m of} the radius function are smaller than the first modeling coefficient bi of the radius function R (cp).

11. Permanent magnet motor (2) with a stator and a rotor rotatably mounted on the stator, wherein the stator or the rotor comprises a magnet having a plurality of magnetic poles, and wherein the magnet comprises a plurality of segment ^¬ magnets (1) according to one of claims 1 to 10 ,