EP2792054A1

EP2792054A1 - Electric motor

Info

Publication number: EP2792054A1
Application number: EP12707269.2A
Authority: EP
Inventors: Martin Hoffmann; Gerhard Huth
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2012-02-28
Filing date: 2012-02-28
Publication date: 2014-10-22
Also published as: US9806588B2; WO2013127436A1; US20150061451A1; KR20140140056A; CN104137394A; JP2015510751A; KR101682408B1

Abstract

The invention relates to an electric motor (10) comprising a rotor (12) which has a plurality of permanent magnets (16) arranged along a circumferential direction (22), a stator arrangement with a winding arrangement which surrounds, at least in parts, the permanent magnets (16). Said stator arrangement comprises a first stator (14) having a plurality of windings and the stator arrangement comprises a second stator (18), the windings of the first and second stators (14, 18) being embodied, respectively as frame-shaped coils (20, 28), said coils (20) of the first stator (14) being arranged in the radial direction (24) on the outside of the permanent magnets (16), the coils (28) of the second stator (18) being arranged in the radial direction (24) inside the permanent magnets (16), and the coils (20, 28) are arranged along the winding axis thereof (26) in the radial direction (24) and the permanent magnets (16) are arranged along the magnetization direction thereof (40) in the radial direction (24).

Description

description

Electric machine

The present invention relates to an electric machine having a rotor which has a plurality of permanent magnets which are arranged along a circumferential direction and a stator arrangement having a winding arrangement which surrounds the permanent magnets at least in regions.

Electric machines in the form of small drives, which have a low energy consumption, are becoming increasingly important. One application for such small drives, for example, small pump and fan drives in Au ^¬ tomatisierungsgeräten. Furthermore, such small drives are preferably used in medical technology. The pro ^¬ project planning of small drives is usually for the maximum occurring drive parameters. Usually, however, these small drives are operated in the so-called part-load range. For the applications of these small drives mentioned above, the drive function is integrated directly into the process in the sense of a mechatronic system. The elekt ^¬ innovative machine is in this case an integrated installation component.

In addition to these structural constraints, these

Small drives be designed to be variable in speed. Thus the drive can for example be formed Converter-fed and have a voltage intermediate circuit with a pulse inverter on ^¬. In the case of portable devices, it is also possible to replace the voltage intermediate ^circuit by a DC voltage source, for example a battery. Particularly for applications in medical technology usually electrical machines are desirable, which can be ^¬ provide a high torque and at the same time have a low Ge ^¬ weight, high energy efficiency, low heating and high smoothness. To achieve this, today usually permanent-magnet AC servomotors are used in conjunction with a pulse converter. In these electrical machines, the stators are usually designed with a wound laminated core, so that with increasing speed Magneti ^¬ sierungsverluste or iron losses increase dominant. Be ^¬ Sonder at partial load lead the virtually load-independent iron losses to a significant deterioration in energy efficiency. In addition, the active parts of such electrical machines usually comprise components made of iron, which represent an undesirable weight component and which can lead to cogging torques.

From EP 1 858 142 A1 a linear motor with a secondary part with permanent magnets and a movable primary part with current-carrying multiphase windings is known. To increase the achievable driving forces, the permanent magnet ^¬ are arranged such that their north and south poles are arranged in the movement direction homonymous succession. In addition, the coils of the polyphase windings are designed such that they surround the permanent magnets of the secondary part at least partially.

The principle of the linear motor described in EP 1 858 142 A1 can likewise be transferred to a rotary motor. In this case, the rotor has a plurality of Permanentmag ^¬ Neten, which are arranged in the circumferential direction. The stator has a winding arrangement which surrounds the permanent magnets at least in regions. For this purpose, the stator has, for example, U-shaped bent coils. However, a production of these coils is very expensive, especially for small rotor diameters.

It is therefore an object of the present invention to provide an electrical machine of the type mentioned, which can be operated energy-efficient and can be manufactured easily and inexpensively. This object is achieved by an electric Ma ^¬ machine according to claim 1. Advantageous Wide Erbil ^¬ compounds of the present invention are given in the subclaims.

The electric machine according to the invention comprises a Ro ^¬ gate having a plurality of permanent magnets disposed along a circumferential direction, a statora ^¬ UTHORISATION with a coil arrangement which surrounds the permanent magnet at least partially, wherein the Statoranord ^¬ voltage a first stator having a plurality of windings and wherein the stator arrangement comprises a second stator, the windings of the first and the second stator are each formed as frame-shaped coils, the coils of the first stator are arranged in the radial direction outside the permanent magnets, the coils of the second stator in the radial direction are arranged inside the permanent ^¬ magnets, the coils are arranged along its winding axis in the radial direction and the Permanentmag ^¬ Neten along their magnetization direction are arranged in the radial direction.

The electric machine includes a rotor in which the permanent magnets are arranged side by side along the circumferential direction of the electric machine. The rotor can be coupled to a corresponding shaft, at which the torque of the electric machine can be tapped. Furthermore, the electric machine comprises a first, outer stator and a second, inner stator. The first and the second stator comprise respective windings in the form of coils, which are each arranged adjacent to each other in the circumferential direction. Thus, the permanent ^{magne ¬} th in the rotor from two sides are surrounded by coils. Thus, a high magnetic force can be provided.

The electric machine can also be designed such that it has only one outer stator or an inner stator. having stator with the associated coils. Alternatively, the electric machine can in addition to the Spu ^¬ len of the first and second stator coils further aufwei ^¬ sen that the permanent magnet at least partially converted ^¬ ben.

The coils of the first and second stator essentially have a frame-shaped form. The coils best ^¬ hen from a wire winding and are in particular constructed as an air ^¬ coils, being so arranged in the ^electrical machine, to be arranged along the winding axis in the radial direction. In other words, the coils have passage openings along which the coils are arranged in the radial direction of the electric machine. These coils can ge ^¬ be fabricated and arranged in the electrical machine as a separate component easy. This type of coils is particularly suitable for the use of electrical machines with a small diameter or small electric drives. Thus, the electric machine needs no grooves and no iron yoke. Thus, no frequency-dependent magnetization losses occur. Furthermore, no cogging torques occur due to the fluctuation of the magnetic conductivity of the stator.

Preferably, the permanent magnets are arranged such that the magnetization directions of juxtaposed permanent magnets are directed in the opposite direction in the radial direction. The magnetization direction of the respective permanent magnets extends from their south pole to their north pole. By such an arrangement of the permanent magnets, a compact design can be achieved in a simple manner. In addition, the permanent magnets can be manufactured as individual parts easily and inexpensively and also a simp ^¬ cher construction of the electrical machine is thus possible.

In one embodiment, the coils have a greater spatial extent in a direction perpendicular to the winding axis than in the direction of the winding axis. In other words, sen the respective coils m the first and the second stator on a flat design. The coils are designed in particular as flat coils. The coils have in the direction perpendicular to the winding axis the greatest possible spatial Aus ^¬ expansion. Thus, an increased force ^¬ effect can be generated on the permanent magnet by the coils. In particular, the coils should be designed such that the ratio of the electrical power introduced into the winding to the mechanical power generated by the electrical machine is reduced. Thus, the higher electromagnetic utilization can produce higher force and torque at a constant current density. In this way, a high torque can be provided with the ^electrical machine.

In one embodiment, the coils in the first and / or in the second stator have a curvature along the circumferential direction of the electric machine. In this case, the coils of the second stator can have a greater curvature in the circumferential direction than the coils of the first stator. Due to the curvature of the coils in the circumferential direction, the electric field of the coils and the magnetic field, which is generated by the permanent magnets of the rotor, perpendicular zueinan ^¬ arranged. Thus, a very high force component in the circumferential direction can be generated, whereby a high torque can be generated with the electric machine.

In a further embodiment, a number of turns and / or a cross-sectional area of a wire of the turns of the coils in the first stator differ from a number of turns and / or a cross-sectional area of a wire of the turns of the coils in the second stator. Thus, depending on the number of turns and / or the wire cross-section, the electric field generated by the coils can be easily adjusted. Likewise, the number of turns and / or the wire cross-section of the coils in the first and second stator can be adapted to the electrical current applied to the coil. Preferably, the permanent magnets are substantially in the form of a hollow cylinder segment. If the electric ^¬ cal machine is designed as a linear motor, cuboid permanent magnets can be used. Permanent magnets, which have such a geometry that can be produced simply and kos ^{¬-effectively.} Also, the permanent magnets ^¬ may have a cylindrical shape. In addition, it is conceivable that the permanent magnets have a curvature in the circumferential direction. This allows a simple and cost- ^effective production of the electrical machine.

Preferably, the number of coils in the first and second stator is a multiple of three. In this case, a coil of the first stator and a coil of the second stator, which are arranged in alignment with one another in the radial direction of the electric machine, are electrically connected in series. ^{Alternatively} , a coil of the first stator may be electrically connected in parallel with a coil of the second stator, so that identical induced voltages result in the first and in the second stator. In this case, the direction of the electric current which is directed in a coil of the first stator and in a coil of the second stator, which are assigned to the same winding segment, directed in opposite directions. Thus, the coils can be easily operated with a three-phase power supply.

In one embodiment, the first and / or the second stator has a carrier structure with a plurality of carrier elements, which are designed to wind up the coils. By the support elements is a kind of winding aid bereitge ^¬ provides. Thus it can be manufactured on simp ^¬ surface, the first and the second stator. Preferably, the support structure and the support members of an electrically insulating material, in particular egg ^¬ NEN material which has a relative permeability of one on ^¬ are made. Due to the electrically insulating material, around which the coils or the windings are arranged, no eddy current losses are caused. Thus, a particular ^¬ DERS energy-efficient operation of the electrical machine can be made possible. In addition, if a material with a relative permeability of μ _Γ = 1 is used, no magnetic reversal losses occur.

The above-described principle of the electric machine and its advantages and developments can also be transferred to egg ^¬ nen linear motor.

The present invention will now be explained in more detail with reference to the accompanying drawings. Showing:

1 shows a schematic perspective view of an arrangement of permanent magnets of a rotor and of coils of a first stator of an electrical machine;

2 shows a representation of the arrangement of the permanent magnets and the coils in a development;

3 shows a sectional side view of the electrical

Machine;

4 shows a plan view of the electrical machine;

5 shows a perspective view of the electric machine;

FIG 6 is a side view of the second stator and the Ro ^¬ tors of the electrical machine;

7 shows a perspective view of an arrangement of the spool of the first and the second stator; and

8 shows a plan view of a support structure of the second

Stator. The embodiments described in more detail below represent preferred embodiments of the present invention.

1 shows in a schematic perspective view of the on ^¬ order of permanent magnets 16 of the rotor with respect to the coils 20 of a first stator of an electrical machine. The permanent magnets 16 have a cuboid shape. The permanent magnets 16 are arranged side by side along the circumferential direction 22. In this case, the permanent magnets 16 are arranged along their magnetization direction 40, which extends from the south pole S to the north pole N, along the radial direction 24. In this case, the permanent magnets 16 are arranged such that the magnetization directions are directed oppositely 40 ne ^¬ by side arranged permanent magnets 16th

The coils 20 of the first stator have a substantially frame-like shape. The coils 20 are arranged in Radia ^¬ ler direction 24 outboard of the permanent magnet 16. In addition, the coils 20 are arranged such that their winding axes 26 are arranged in the radial direction 24 of the electric machine.

2 shows the arrangement of permanent magnets 16 and coils 20 in a development. The electric machine is so formed from ^¬ that the number N * of the coil 20 is a multiple of the number three. Thus, the coils 20 can be connected to a dreipha ^¬ sigen power supply. Thus, an electric machine with the base pole number 2p is formed. The following rules apply:

The number of frame coils N * must be divisible by three:

n For the quotient of the constant p / n, it must hold that p / n is an integer, in which case it must hold that n Φ 3, 6, 9 ^ · · · »If z is an even number, then every winding phase exists from 2p / n coil groups each with z / 2 frame coils.

In the present case, the abovementioned laws for a 10-pole design of the electrical machine are shown. Thus the basic pole number is 2p = 10. This results from the quotients of the constants z / n = 2/5. Each winding side then consists of N * = ^ ^ ^Z = ^ ^ ^ = 6 frame coils.

n 5

Each of the three winding phases consists of 2p / n = 10/5 = 2 coil groups each with z / 2 = 2/2 = 1 frame coils.

In the illustrations in Figures 1 and 2 respectively the arrangement of the permanent magnets 16 and the coils 20 is shown by an electric machine having a first, outer stator. The electric machine preferably also comprises a second, internal stator, in which the coils are arranged in the radial direction 24 on the inside of the permanent magnet 16.

3 shows a sectional side view of an electric machine 10 having ten poles. The electric machine 10 comprises a rotor 12, which is mechanically connected to a shaft 30. Moreover, the rotor 12 includes a plurality of permanent magnets 16 disposed on a radial disk and an axial hollow cylinder. Furthermore, the electric machine 10 comprises a first

Stator 14 having a plurality of coils 20. In addition, the electric machine comprises a second stator 18 having a plurality of coils 28. The coils 20 of the first stator 14 and the coils 28 of the second stator have a curvature in the circumferential direction 22 of the electric machine 10 on. Likewise, the permanent magnets may have a curvature along the circumferential direction 22. 4 shows the electrical machine 10 according to FIG 3 in a plan view. In this case, the rotor 12 of the electric machine can be seen, which has ten permanent magnets 16. In addition, the first stator 14, which has six coils 20, is shown. The coils 20 of the first stator 14 are arranged in the radial direction 24 of the electric machine 10 outside of the permanent magnets 16 of the rotor 12. Likewise, the second stator 18 comprises six coils 28. In this case, the coils 28 of the second stator 18 are arranged in the radial direction 24 inside the rotor 12.

5 shows a perspective view of the electric machine 10 from the underside. In particular, the coils 20 of the first stator 14 can be seen. 6 shows a partial view of the electric machine 10 without the first stator 14. In this case, the rotor 12 of the electric machine 10 with the permanent magnet 16 can be seen. Furthermore, the coils 28 of the second stator 14 are shown.

7 shows in a perspective view the arrangement of the coils 20 of the first stator 14 and the coils 28 of the second stator 18. The coils 20, 28 each have a frame-shaped in Wesent ^¬ union structure. The coils 20, 28 are made by a wound wire and thus form a corresponding air-core coil. In this case, the coils have a smaller spatial extent along the winding axis 26 than in a direction 32 which runs perpendicular to the winding axis 26. In other words, the coils 20, 28 have a flat design. In particular, the coils 20 are intended to 28 be formed so that the ratio of the electric power, which is introduced in the winding, is reduced to the mecha ^¬ African performance. Thus, a higher power and a higher torque can be generated at a constant current density. Furthermore, the coils 20, 28 are curved along the circumferential direction of the electric machine 10. As shown in FIG. 7, the number of turns of the coils 20, 28 may differ. The coils 28 of the second stator 18 have a smaller number of windings on in this case, as the coils 20 of the first stator 14. In this case, the cross-section ^¬ surface of the wires of the coils 20 of the first stator 14 as compared to the cross-sectional area of the wires of the coils 28 be formed differently in the second stator 18.

8 shows a plan view of the support structure 34 of the 18 in ^¬ Neren stator Here, the support structure 34 has a plurality of support elements 36. The carrier elements 36 are formed by a projection in the radial direction, which has a two-sided recess 38. In this recess 38, the wire can be introduced and thus the respective coils 28 are wound. The carrier structure 34 and the carrier elements 36 are preferably formed from an electrically insulating material, which in particular has a relative permeability of one.

Reference sign list

10 electric machine

12 rotor

14 stator

18 stator

20 coil

22 circumferential direction

24 direction

26 winding axis

28 coil

30 wave

32 direction

34 carrier structure

36 entrant

38 recess

40 magnetization direction

North pole

S south pole

Claims

claims

1. Electric machine (10) with

a rotor (12) having a plurality of permanent magnets (16) arranged along a circumferential direction (22),

- A stator assembly having a winding arrangement which surrounds the permanent magnets (16) at least partially, wherein

the stator arrangement has a first stator (14) with a plurality of windings,

characterized in that

the stator arrangement has a second stator (18),

- The windings of the first and second stator (14, 18) are each formed as frame-shaped coils (20, 28), - The coils (20) of the first stator (14) in the radial direction (24) on the outside of the permanent magnet (16 ) are arranged

the coils (28) of the second stator (18) are arranged in the radial direction (24) on the inside of the permanent magnets (16),

- The coils (20, 28) along its winding axis (26) in the radial direction (24) are arranged, and

- The permanent magnet (16) along its magnetization direction (40) in the radial direction (24) are arranged.

2. Electrical machine (10) according to claim 1, characterized in that the permanent magnets (16) are arranged such that the magnetization directions (40) of juxtaposed permanent magnets (16) are directed in the opposite direction in the opposite direction.

3. Electrical machine (10) according to claim 1 or 2, characterized in that the coils (20, 28) in a direction (32) perpendicular to the winding axis (26) have a greater spatial extent than in the direction of the winding axis (26).

4. Electrical machine (10) according to one of the preceding claims, characterized in that the coils (20, 28) in the first and / or in the second stator (14, 18) have a curvature along the circumferential direction (22) of the electric machine (10).

5. Electrical machine (10) according to one of the preceding claims, characterized in that a number of turns and / or a cross-sectional area of a wire of the turns of the coils (20) in the first stator (14) of a number of turns and / / or a cross-sectional area of a wire of the turns of the coils (28) in the second stator (18).

6. Electrical machine (10) according to any one of the preceding claims, characterized in that the permanent magnets (16) have substantially a shape of a hollow cylinder segment.

7. Electrical machine (10) according to one of the preceding claims, characterized in that the number of coils (20, 28) in the first and second stator (14, 18) is a multiple of three.

8. Electrical machine (10) according to one of the preceding claims, characterized in that the first and / or the second stator (14, 18) have a support structure (34) with a plurality of support elements (36) for winding the coils (20, 28) are formed.

9. Electrical machine (10) according to claim 8, characterized in that the carrier structure (34) and the carrier elements

(36) made of an electrically insulating material, in particular of a material having a relative permeability of one, is made.