WO2008015151A1

WO2008015151A1 - Linear motor with force ripple compensation

Info

Publication number: WO2008015151A1
Application number: PCT/EP2007/057703
Authority: WO
Inventors: Zeljko Jajtic; Christian Volmert
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-07-31
Filing date: 2007-07-26
Publication date: 2008-02-07
Also published as: DE102006035675A1

Abstract

The invention relates to a primary component (2) for an electric motor (1), wherein a) the primary component (2) is provided for arrangement with a secondary component (7), the primary component (2) and secondary component (7) are separated from each other by an air gap (δ), b) the primary component (2) is formed by at least one bundle of laminations (3) and comprises at least one flux guiding element (10) on the front faces (S1, S2) thereof to reduce the force ripple effect, c) the flux guiding element (10) has a definable width (B10) and length (L10) the width (B10) being variable and the width (B10) of the flux guiding element (10) in the region of the side facing the air gap (δ) is reduced.

Description

description

Linear motor with force ripple compensation

The invention relates to a primary part for an electrical

Machine, wherein the primary part is provided for arrangement with a Sekun ^¬ därteil and primary and secondary are spaced apart by an air gap and the primary ^¬ part is at least formed from a laminated core and at its respective end faces at least one flow-guiding ele ^¬ ment for reduction having the force ripple, wherein the flux guiding element has a predetermined width and length ^¬ , wherein the width is variable. Furthermore, the invention relates to a ^¬ linear motor with such a primary part.

Linear motors have a primary part and a secondary part. The primary part is in particular the secondary part opposite. The primary part is intended to be supplied with electric current. The secondary part has, for example, permanent magnets or energizable windings. Both the primary part and the secondary part have active magnetic means for generating magnetic fields.

Permanent-magnet linear motors have design-related power fluctuations due to motor ends, which have an adverse effect on synchronism and dynamics. The power fluctuations can be traced back to the border coil in part to a smaller induced tension ^¬ calculations.

In order to guide the magnetic flux of exciting field of the secondary part and the main field of the primary part, the toothed plates are usually used in the active winding-carrying part of the motor (primary part). Between the excitation poles and the toothed structure of the main field, a magnetic interaction takes place, which leads to parasitic detent forces, also called passive force ripple. The result is Vibra ^¬ tions, uneven running and drag error in machining processes. Furthermore, the induced voltages, ie the electromotive forces (EMF), in the initial and final coil on the front sides of the primary part due to a fe ^¬ lenden magnetic yoke usually less pronounced than in the middle coil. This has the result that the induced voltages of the motor do not form a symmetrical Sys tem ^¬ and called addition power loss of an additional current-dependent force ripple, and active force ripple results.

From US 6,831,379 B2, a linear motor is known, whose primary part at the end faces of the laminated core of the main ^¬ teeth having additional auxiliary teeth, said auxiliary teeth are spaced from the air gap between the primary and secondary parts by ei ^¬ NEN additional air gap. This reduces the passive force ripple of the linear motor, ie the latching force.

The disadvantage here is that although the latching force of the Linearmo ^¬ sector is reduced, the primary part, however, has no symmetrically induced voltages in the individual windings or coils, ie there is no reduction of the active power ripple.

Object of the present invention is therefore to develop a generic linear motor such that in addition to the reduction of the detent forces and a balancing of the electromotive forces takes place.

The object is solved by the features of claims 1 and 10. Advantageous developments are given in the Unteransprü ^¬ chen.

In contrast to rotating machines, linear motors naturally have end regions in which the electromagnetic part of the motor ends. Is a linear motor constructed, for example in short stator, will be apparent to the ^primary part two end portions which are beyond the control of the secondary ^¬ part. The ends of the primary interact with the Secondary part such that this has a significant influence on the active force ripple and passive Kraftwellig- speed (cogging force).

The primary part according to the invention is provided for arrangement with a secondary part, wherein the primary part and the secondary part are spaced apart by an air gap. The ^secondary part has a series of ge ^¬ formed by permanent magnets Poland. The primary part is formed from one or more laminations, wherein the laminated core of a

Variety of sheets is constructed. The primary part has a plurality of grooves and teeth, wherein the grooves serve to receive the primary part windings or coils. The windings are designed, for example, as a three-phase winding of a three-phase network or of a three-phase alternating current.

The linear motors are formed in particular with Bruchlochwicklungen and tooth coils in the primary part, wherein the Nuttei- ment of the primary part is not equal to the pole pitch of the secondary part. For example, the ratio of Nuttei ^¬ ment to pole pitch (slot pitch / pole pitch) = 8/12, 10/12, 11/12, 13/12, 14/12, 16/12.

A flux guiding element for reducing the Kraftwel ^¬ ligkeit depending ^¬ weils arranged on the end sides of the sheets or of the laminated core. The flux-guiding element has a front ^¬ can be predetermined width and length, the width over the length is variable. The width of the flux guiding element is reduced in the area of the air gap facing side. The flow-guiding element is for example designed such that it has a taper in the direction of the air gap. The length of the flux-guiding element corresponds to the length of the remaining teeth of the primary part.

The flux-guiding element is attached to the end faces of the single ^¬ NEN sheets or of the entire laminated core and be ^¬ takes place at or next to the respective last of the groove or last wound tooth of the primary part. The flux guiding element itself carries no winding or coil.

By attaching such a flux-guiding element, in addition to the reduction of the passive power ripple, also a reduction of the active force ripple possible by the flux linkage with the last coil by shaping, ie reduced width of the flux guiding element in Luftspaltbe ^¬ rich, is selectively influenced. The induced voltages in the winding-carrying end teeth of the primary part are raised, in which case the aim is a uniform possible EMF in all coils of the primary part.

Preferably, the width of the flux guiding element is reduced by bevels in the direction of the air gap. The flux-guiding element can take a variety of geometric shapes in the region of the air gap supplied ^¬ facing side. If, for example, two partial surfaces are assigned to the flux-guiding element, with the first partial surface facing the air gap and the second partial surface facing away from the air gap, the first partial surface is, for example, triangular or arrow-shaped. By chamfering a reduced width is easy to implement. Usually comprise a plurality of individual sheets to such sloping flux guiding element, so that then a flux guiding element in ^¬ play results over several hinte purely ^¬ other arranged sheets in the form of a pyramid, a truncated pyramid or a prism.

In a further embodiment, the flux-guiding element is designed so that it partially or completely rests on a neigh ^¬ beaten winding or coil for heat exchange. As a result, an improved cooling of the winding or coil takes place.

Advantageously, the laminated core is integrally formed together with the flux ^¬ leading element. The flux guiding element is already formed when making the sheets, that is, there is a one-piece metal section, whereby a simple and cost-effective production of the individual sheets with flux-conducting elements is possible.

Laminated core with flow-guiding element can also be formed in two parts, wherein the flux-guiding element is non-positively, material or form-fitting attachable to the laminated core. The flux guiding element itself can also be formed in two parts.

Furthermore, the flux-guiding element to the or to be wound ^¬ adjacent teeth of the laminated core to a distance. Advantageously, the distance of the flux-guiding element to the or the adjacent teeth is selected so that it corresponds to the pole pitch of the secondary part, so ei ^¬ ne highest possible Flußverkettung with the last coil and thus a deliberate increase in the induced voltage of the last coil.

For a space-optimized design of the linear motor, a minimum width and the smallest possible distance of the flux-guiding element are sought. This results in an optimum distance of the flux guiding element from the adjacent wound tooth, which is smaller than the pole pitch of the secondary part.

For example, a high attraction force between primary and secondary part aimed at, for example for the purpose of biasing force ^¬ at an air storage, the optimal distance of the flux guiding element of the adjacent tooth is greater than the pole pitch of the secondary part formed.

Preferably, the air gap facing surface of the flux guiding element is rounded. The flux-guiding element has, for example, with a predetermined radius abgerunde ^¬ te corners. This measure contributes to the reduction of the locking ^¬ forces. It is possible not to provide each sheet with a flux guiding element. For example, only every second sheet has a flux guiding element. In a ^¬-part primary parts, ie primary parts package having only one sheet metal, it is possible that each plate has only one flux guiding element at an end portion of the sheet. The individual sheets can then be joined together, for example, to the laminated core, that by rotating the individual sheets, the flux-guiding element is aligned once to the left or to the right. The force ripple is thus sufficiently reduced compared to the previously known possibilities, wherein in addition a lower mass of the primary part is achieved by plates without flux-conducting elements.

The primary part of the linear motor may consist of several successively arranged in BEWE ^¬ supply direction laminated cores. Accordingly, the centrally arranged laminated cores have no flux-conducting elements, but according to the invention only flux-guiding elements are arranged at the respective ends, thus the end faces of the primary part. In this case, for example, by turning a sheet with rechtsseitigem element a sheet with left-sided element, so that on the front sides of these primary parts gapless elements are present. For primary parts with only one laminated core, ie one-piece primary parts, flux-conducting elements must be provided at each end.

In a further embodiment of the invention, the flux-guiding element is not formed over the entire width of a Blechpa- kets. The width of the laminated core extends transversely to the direction of movement of the primary part. Thus, for example, the flux-guiding element extends only over a part ^¬ area of the laminated core, wherein the flux-guiding element may then be arranged for example centrally in the laminated core. Due to the formation of only partially flux guiding elements, the adaptation between passive and active force ripple can be made according to the requirements of the linear motor. The flux guiding element serves to reduce the latching force over the length of the primary part and to increase the useful force of the linear motor.

The primary part according to the invention is preferably provided for a linear motor. However, the primary part can also be used in rotary machines, wherein the stator has end regions, such as segmented rotato ^¬ rische motors.

In the following description, further features and details of the invention in conjunction with the accompanying drawings will be explained in more detail by means of exemplary embodiments. In this case, features and relationships described in individual variants can in principle be applied to all exemplary embodiments. In the drawings show:

1 shows a side view of a linear ^motor according to the invention with a first embodiment of a flux-guiding element;

2 shows a section of a primary part of a Linearmo ^¬ sector of FIG 1 with a second embodiment of the flux-conducting element.

3 shows a section of a primary part of a linear motor according to FIG 1 with a third embodiment of the flux-conducting element;

4 shows a section of a primary part of a Linearmo ^¬ sector according to FIG 1 with a fourth embodiment of the flux-conducting element; 5 shows a section of a primary part of a Linearmo ^¬ sector according to FIG 1 with a fifth embodiment of the flux-conducting element;

6 shows a detail of a primary part of a Linearmo ^¬ sector according to FIG 1 with a sixth embodiment of the flux-conducting element.

1 shows a side view of a principle ^{dargestell ¬} th synchronous ^linear motor 1, the one or more laminated cores 3, whose respective sheets are layered parallel to the plane of the drawing and which form the primary part 2. The BEWE ^¬ supply direction of the linear motor 1 is attached give ^¬ by the arrow R. The primary part 2 also has the coils 4. The coils 4 enclose the teeth 5 of the primary part 2 in such a way that different coils 4 are located in a groove 6. Furthermore, the linear motor 1, the secondary part 7 with the permanent magnet 8. The secondary part 7 is positioned on a machine bed, not shown. The permanent magnets 8 are arranged with the pole pitch τ _M. The pole pitch τ _M can also be formed by electrical excitation of an exciter winding arranged in the secondary part 7. Primary part 2 and secondary part 7 are spaced apart by the air gap δ. At the end faces Sl and S2 of the laminated core 3, a flux guiding element 10 for reducing the force ripple is arranged in each case.

The flux guiding element 10 has the predeterminable width Bi ₀ , wherein the width Bi _{0 of} the flux guiding element 10 extends in the direction of movement R of the primary part 2. The mush ^¬ te Bio of the flux guiding element 10 is reduced in the region of the air gap δ side facing. For example, the flux guiding element 10 is designed such that it has a taper in the direction of the air gap .delta. In particular, the flux-guiding element 10 is δ in the region of the air gap ^¬ with a predetermined radius of rounded design. The length Li _{0 of} the flux-guiding element 10 corresponds to the tooth length L _{5 of} the remaining teeth 5.

Furthermore, the flux-guiding element 10 to the Benach ^¬ disclosed wound tooth 5 of the laminated core 3 at a distance τ _F on. Advantageously, the distance τ _F is chosen equal to τ _M , so that the highest possible flux linkage with the last coil 4 and thus a desired increase in the induced voltage of the last coil 4 takes place. For a space-optimized design of the linear motor 1, a minimum width Bi ₀ and the smallest possible distance τ _{F of} the flux- ^guiding element 10 to the adjacent tooth 5 are aimed for. FIGS. 2 to 6 show different embodiments of the flux-conducting element 10.

2 shows a flux guiding element 10, the width Bi ₀ in the direction of the air gap δ is reduced by a bevel on the front side S2.

3 shows a flow-carrying element 10 whose width B is ₀ δ in the direction of the air gap sheet reduc- by two chamfers, resulting in an arrow-shaped or triangular FLAE ^¬ che or shape results.

In FIG 4 it is shown that the element has two different widths ^¬ Liche Bi ₀ without chamfers.

Figures 5 and 6 show elements 10, which are formed ^¬ jüngend δ on the one hand to ver in the direction of the air gap and on the other hand, ^¬ a variable distance τ _F have the neighboring wound tooth. 5

In the region of the side facing away from the air gap δ, the element 10 extends along the adjacent coil or winding 4, whereby improved cooling of the last coil or winding 4 is achieved.

Claims

claims

1. primary part (2) for an electrical machine (1), wherein a) the primary part (2) for arrangement with a secondary part (7) is provided and primary part (2) and secondary part (7) by an air gap (δ) spaced from each other is b) are ge forms, the primary part (2) of at least one laminated core (3) ^¬ and (at its respective end faces Sl, S2) at least one flux guiding element (10) for reducing the force ripple has, c) the flux-guiding element (10 ) has a predefinable width (Bi ₀ ) and length (Li ₀ ), wherein the width (Bi ₀ ) is variable, characterized in that the width (Bi ₀ ) of the flux guiding element (10) in Be ^¬ rich the the air gap (δ ) facing side is reduced.

Second primary part (2) according to claim 1, characterized in that the primary part (2) has a plurality of teeth (5) with a tooth length (L ₅ ), wherein the length (Lio) of the flux guiding element (10) of the tooth length (L ₅ ) ent ^¬ speaks.

3. primary part (2) according to claim 1 or 2, characterized in that the width (Bi ₀ ) of the flux-guiding element (10) by chamfers in the direction of the air gap (δ) is reduced.

4. primary part (2) according to one of claims 1 to 3, char - characterized in that the flux ^¬ leading element (10) partially applied to an adjacent Wick ^¬ ment or coil (4).

5. primary part (2) according to one of claims 1 to 4, char - characterized in that the Blechpa ^¬ ket (3) with the flux-conducting element (10) is formed in one piece or in two parts.

6. primary part (2) according to one of claims 1 to 5, since ^{¬ characterized in} that the flux ^¬ leading element (10) non-positively, material or positively on the laminated core (3) is attachable.

7. primary part (2) according to one of claims 1 to 6, since ^{¬ characterized in} that the flux ^¬ leading element (10) by a predetermined distance (τ _F ) from an adjacent main tooth (5) of the primary part (2) is spaced, wherein for the distance (τ _F ) applies: τ _F ≤ X _M , where ^¬ at τ _{M is} the pole pitch of the secondary part (7).

8. primary part (2) according to one of claims 1 to 6, since ^{¬ characterized in} that the flux-guiding element (10) by a predetermined distance (τ _F ) from an adjacent main tooth (5) of the primary part (2) is spaced apart, wherein for the distance (τ _F ) applies: τ _F > τ _M , where ^¬ at τ _{M is} the pole pitch of the secondary part (7).

9. primary part (2) according to one of claims 1 to 8, as ^¬ by in that the air gap (δ) facing surface and / or corners of the flussfüh ^¬ leaders element (11) are rounded with a predetermined radius.

10. linear motor (1) having at least one primary part (2) and at least one secondary part (7), wherein primary part (2) and secondary part (7) by an air gap (δ) are spaced from each other, and the primary part (2) at least one Sheet metal packet (3) is formed and at its respective front ^¬ sides (Sl, S2) at least one flux guiding element (10) for reducing the power ripple, characterized in that the linear motor (1) is a primary part (2) according to one or more of the claims 1 to 8.