WO2018215085A1

WO2018215085A1 - Method for reducing stray fields in inductive energy transmission

Info

Publication number: WO2018215085A1
Application number: PCT/EP2018/000233
Authority: WO
Inventors: Mauricio Esguerra
Original assignee: Magment Ug (Haftungsbeschränkt)
Priority date: 2017-05-02
Filing date: 2018-05-02
Publication date: 2018-11-29

Abstract

The invention relates to a method for inductive energy transmission, wherein an alternating magnetic field (6) provided by a transmitting assembly (1) magnetically interacts with a receiving assembly (7). In order to reduce stray fields, the transmitting assembly (1) is at least partially provided with stray-field-shielding layer (12) of metamaterial in the region of the transmitting assembly that faces away from the receiving position of the receiving assembly. Said layer is formed from a plurality of identically constructed coil antenna elements (14), which are applied to a polymer film in planar, regular arrangement and which each comprise conducting tracks (16) forming a coil, having an integrated capacitor (18). By adjustment of the inductance and capacitance, the permeability of the layer (12) can be set in such a way that, at the operating frequency of the alternating magnetic field, a shielding effect and thus an effective reduction in the transmission losses due to stray fields are achieved. The coil antenna elements can be favorably designed in the manner of modified RFID elements.

Description

Method for reducing stray fields during inductive energy transmission.

The invention relates to a method for reducing stray fields in the inductive energy transmission, in which a by a transformer coil containing

Transmitter arrangement provided, having a substantially constant operating frequency having alternating magnetic field in magnetic interaction with a brought into a receiving position, preferably a receiver coil containing

Receiver arrangement occurs, wherein the Übertrageranordnung in its the receiving position of the receiver assembly remote area has a stray field shielding layer of metamaterial. The invention further relates to a transformer arrangement and a receiver arrangement for carrying out such a method, the use of the metamaterials in such a method or in Übertrageranordnung or the receiver assembly, and the use of the metamaterials in the inductive

Energy transfer by means of magnetic alternating fields, which have a substantially constant operating frequency.

A method of the type mentioned is known from US 2013/0088090. In this case, a system is used, which basically consists of three main components, namely a

Power source, a magnetic transformer assembly and a receiver assembly is constructed. The described transformer arrangement comprises a ferrimagnetic

Component, a coil and a shield. The latter has the task of blocking unwanted stray fields and thereby enabling improved energy transfer. As shielding materials according to this application materials with

diamagnetic behavior, superconducting material, metamaterial, superconducting metamaterial, an actively excited circuit or other diamagnetic material are proposed. The metamaterial can be designed inter alia as a so-called split-ring resonator, for example as a ring coil structure on a printed circuit board. At high frequencies, the resonance of the inductance of the ring with its own parasitic capacitance may be sufficient to achieve the desired resonant frequency. At low field frequencies it may be necessary to bring the material into the resonant structure required for the action as a metamaterial by adding an external capacitor with an inductive coil. The described systems are intended for use in static or dynamic charging of electrically powered vehicles. Although the superconductors proposed in the cited application fundamentally represent a low-loss diamagnetic material, they show the desired behavior only at low temperatures and are therefore out of the question in practice for use because of the expense for the cooling required. Less expense for cooling would require the use of metal shields due to the induced

Eddy currents at high frequencies may also have effective diamagnetic behavior. However, the eddy currents inevitably lead to a disadvantageous for the efficiency reduction of the coil quality. The mentioned in the said application also as a possible shielding

Metamaterial requires, especially when it comes to the shielding of larger areas, the use of a variety of in their inductance and capacitance exactly to the frequency of the alternating magnetic field matched individual elements. It is difficult and associated with the production of correspondingly great effort to comply with these parameters with the required accuracy for each of the individual elements of such a variety. This applies in particular if the metamaterial, as proposed in the cited application, is designed as a so-called split-ring resonator, for example as a printed circuit board with a conductive coil with a gap and a capacitor connected to the coil ends. Such arrangements also have a non-negligible thickness, which is disadvantageous in some applications where space is limited.

The object of the invention was based on this prior art, a

Specify metamaterial for use in the process and in a transformer assembly and a receiver assembly, which allows effective shielding of stray fields in a small footprint, can be produced with little effort and allows precise compliance with the parameters inductance and capacity.

This object is achieved by a method having the features of claim 1. In the method according to the invention the layer of metamaterial is formed by a plurality of identically constructed coil antenna elements, which are applied in a planar, regular arrangement on a polymer film and each forming a coil

Include interconnects with integrated capacitor whose inductance and capacitance are coordinated so that the layer at the operating frequency of the alternating magnetic field stray field has shielding effect. Preferred embodiments of the method according to the invention are shown in the dependent claims.

In the method according to the invention can be used to form the shielding layer of metamaterial advantageous coil antenna elements, which in principle similar to those in RFID technology (RFID = radio-frequency identification, by means of electromagnetic waves) as a transponder (often referred to as radio tag) conventional passive coil antenna elements are designed. Such passive

Coil antenna elements have the advantage of being in contrast to active ones

Coil antenna elements for their function not on their own energy sources such.

Batteries or batteries are dependent, which do not remain unlimited in time. The essential constituents include those used according to the invention

Coil antenna elements usually a thin, advantageously flexible carrier film

Polymer material with printed conductors in the form of a flat coil with integrated capacitor. An essential modification to most common passive RFID coil antenna elements is that they can be stored in

Transmission or readout of information transistor chips are integrated, while the coil antenna elements used in the method according to the invention need not contain such transistor chips, as these are not required for the present invention desired function, namely the extensive or complete shielding of stray fields.

The planar, regular arrangement of the coil antenna elements on a polymer film is ultimately an array of resonators whose resonant frequency is tuned by tuning the available inductance and capacitance, i. essentially on the design of the tracks and dimensioning of the capacitors, in certain desired

Areas can be brought. Accordingly, can be at given

Operating frequency of an alternating magnetic field, the inductance and capacitance of the tracks and capacitors of each identically constructed coil antenna elements so coordinated that they represent resonators in a frequency range in which no or only low permeability for the necessarily the operating frequency of the alternating magnetic field having stray fields is to be expected. In this

Frequency range, which is usually well below the operating frequency of the alternating magnetic field and typically also above the resonant frequency of the individual Coil antenna elements is, therefore, the respective present collective of the coil antenna elements can act as a metamaterial, which is able to effectively shield the stray fields. The frequency ranges suitable for this purpose can be estimated, for example, with the aid of the curves which determine the frequency dependence of the permeability for the respective metamaterial

Ueff ''). Such curves can, for example, by

Measurements, but often also be created with the help of simulation calculations. Under Uef 'is the real component, under Uefr "to understand the imaginary component of the effective permeability.The term" effective permeability "is to be used in the context of the present application in the sense of those meaning of

J.B. Pendry was developed for metamaterial structures and, for example, in J.B. Pendry et al., IEEE TRANSACTIONS ON MICRO WAVE THEORY AND

TECHNIQUES, VOL. 47, NO. 11, NOVEMBER 1999, Magnetism from Conductors and Enhanced Nonlinear Phenomena. For the achievement of a stray field shielding effect, it has proved to be advantageous to match the inductance and capacitance to each other so that at the operating frequency of the alternating magnetic field an effective permeability of Ueff '<1, preferably between 1 and 0, in particular between 0.2 and 0. With particular advantage inductance and capacitance are tuned so that metamaterial in the frequency at which the intersection of the curve of Ueff 'and Ueff "is approximately equal to the operating frequency of the alternating magnetic field.However, it is not necessary that these frequencies exactly In most cases, a tolerance range of + 20%, advantageously + 10%, is sufficient to ensure a low permeability of the metamaterial for the present magnetic field and thus also an effective

Shielding of stray fields to achieve.

The method according to the invention can be used over a wide frequency spectrum and is used particularly favorably in areas where magnetic fields with standardized operating frequencies are provided. Examples of such applications are the inductive energy transfer in the field of electromobility, where operating frequencies of the magnetic fields have proven between 10 kHz to 100 kHz, which was determined by convention as the standard operating frequency 85 kHz. In the field of heat generation, on the other hand, as essentially constant operating frequencies, those which are mostly selected from the range of 10 kHz to 50 MHz are used. It is not excluded to lower the lower limit to about 50 Hz. In general, it has proved to be advantageous if the operating frequency of the alternating magnetic field is subjected to the smallest possible fluctuations. Thus, the respectively intended operating frequency should expediently be maintained with an accuracy of at least + 5%, preferably at least + 2%, particularly preferably + 1%. The advantages of the invention are usually particularly noticeable when high amounts of energy are transferred, so that energy losses caused by stray fields and / or risks with regard to electromagnetic environmental compatibility are not negligible. This applies to a large extent, for example, for the inductive energy transfer in the field of electromobility.

An advantage of using coil antenna elements which are in the nature of

modified RFID coil antenna elements, is that you can rely on the available and proven in RFID technology for their production process. These production methods are known to the person skilled in the art; as an example, reference is made to the methods described in US 2006/0043199 A1. As a rule, during production, the respectively selected coil patterns are applied in a manner known per se in the form of printed conductors to a polymer carrier film, to be precise by means of printing or etching processes. This can be done for example with particular advantage by printing processes using conductive inks, such as stamp printing or inkjet printing, but also by etching, for example dry etching of metallized carrier films, or by electrodeposition, sputtering or photolithographic processes.

As materials, which ensure the electrical conductivity of the conductor tracks, are preferably metals, in particular aluminum or copper, but also silver, gold or nickel, optionally also in the form of alloys in question. Experience has shown that in printing or electrodeposition processes copper or silver have proven useful, for example for conductive inks, while etching is often used in aluminum. For cost reasons, aluminum is often preferred. However, this information is not intended to be limiting; In some cases, it may also be expedient, for example, to use conductive tracks based on conductive polymers. The conductor tracks are advantageously applied to the carrier foil in such a way that they are located on the periphery of the coil antenna elements in their respectively provided surface form, while the central region of the elements is kept free of conductor tracks. This not only has the advantage of saving material but has also been found to be beneficial for reducing and shielding stray fields. Basically, however, too

Embodiments are not excluded in which the traces utilize the entire available surface area of the coil antenna elements. It has continued to prove itself in the

Corner area to run the tracks curvy and tips to avoid. The surface shape of the coil antenna elements is suitably chosen so that a

Variety of them can be brought into a dense planar arrangement to each other. Favorable are therefore rectangular or square as well as trigonal or hexagonal shapes, with which an approximately complete area coverage can be achieved if the elements are arranged in rows in rows and these rows next to or above or below each other. In cases where such full area coverage is not mandatory, circular, oval or polygonal, e.g. octagonal coil antenna elements are used. In general, it has proved to be advantageous to apply a plurality of coil antenna elements in each case to a carrier film web. While for the production of RFID tags still a singulation step

can be made, such a separation of the elements is usually waived when it comes to use as a metamaterial. This requires a regular, for example, periodic arrangement of the coil antenna elements. It is therefore particularly advantageous to apply the plurality of individual elements already in the arrangement to one another on the carrier film web, as provided and required for use as a metamaterial. Experience has shown that the number of individual elements should be at least 4, so that the shielding effect of the metamaterials comes into play. However, it may in many cases be significantly higher, for example, when shielding surfaces that are significantly larger than the area of a single coil antenna element by the layer of metamaterial. In general, one will also select the surface shape and area extent of the coil antenna elements to the effect that they on the one hand, the conductor tracks in the required length and the

Capacitor can record, and on the other hand allow the fullest possible use of the film width. In this case, the distance of the individual elements from each other can be kept low and can often be reduced to up to 1.5 mm. In many cases it is it is possible to maintain conventional patterns for the course of the interconnects in RFID elements, while only the capacitor is adapted to achieve a resonator behavior suitable for use as a metamaterial, which can be effective at the frequencies of the alternating magnetic field used for inductive energy transmission. In some cases, it may also be necessary to electrically connect each two or more adjacent individual elements, for example by parallel connection, in order to reduce the resulting resistance. It may also be appropriate to use a bilaterally provided with coil antenna elements carrier film web, the conductor tracks z. B. interconnected by conductive through holes (vias).

Experience has shown that the number of composite elements produced in this way should then be at least four in order to ensure the shielding effect of the metamaterial.

The film thickness of the carrier film is suitably in the range of 10 to 300 μηι, advantageously 20 to 250 μπι, in particular 25 to 125 μιη. As a film material usually used in RFID technology polymers are used, such as those based on polyethylene, polypropylene, polyimide or preferably polyethylene terephthalate. In the case of the production of the printed conductor pattern by etching processes, it may be expedient to use as starting material a metallized polymer film, for example an aluminum-coated polyethylene terephthalate film.

By dimensioning the tracks in terms of length, cross-section and distance from each other and the number of turns, the inductance of the coil formed can be adjusted. It usually depends on the given

Operating frequency of the alternating magnetic field, the resulting

Resonance conditions, and the expected currents and voltages.

For example, for magnetic fields whose operating frequency is in the range of 10 kHz to 100 kHz of interest for applications in the field of electromobility,

Printed conductors with a width of 0.5 to 5 mm and a length of 0.1 to 10 m,

preferably 0.5 to 5 m proven, the number of turns is suitably between 2 and 20, favorably chosen between 2 and 12. Often, for reasons of space, the

Upper limit of 12 turns should not be exceeded. In general, the optimum dimensioning can be determined, for example, by simulation calculations, possibly in conjunction with preliminary tests. The capacitance required by the individual coil antenna elements for generating the frequency response leading to the desired shielding effect of the metamaterial can be conveniently provided by conventional capacitors.

Conveniently, as flat as possible or small-volume capacitors are selected to, if they are integrated to form the coil antenna elements in the interconnects to keep the supernatant on the film surface and thus their unevenness as low as possible. For example, ceramic capacitors, in particular ceramic multilayer capacitors (MLLC) or polymer capacitors, have proven to be useful, since they are available on the one hand in a small size and, on the other hand, also have a high degree of robustness against high current intensities which sometimes occur. The capacitors are usually integrated in such a way that their supply lines with the endpoints of the in

Coil form applied conductor tracks are connected. The respective required capacity can be estimated, for example, with the help of simulation calculations and, if necessary, optimized in connection with preliminary tests. As a guide, e.g. that capacitance range can be used within which, in conjunction with the present inductance, a behavior of the resonators results, which causes an effective permeability of Ueff '<1 at the operating frequency of the alternating magnetic field. To a defined, reproducible and uniform behavior of the individual

To ensure coil antenna elements as resonators within the plurality and thus of the metamaterials overall, it is advantageous to make sure that the specified capacitances are subject to the lowest possible fluctuations in the selected capacitors and are kept within close tolerances as accurately as possible. As a rule, fluctuations of about ± _5% are still acceptable; however, it is advantageous if the fluctuations amount to only ± 2%, in particular only + 1%. In most cases, the shielding effect of the metamaterial is reduced when the capacitances of the individual capacitors within the plurality are + 10% or more apart. It has proven useful to provide the coil antenna elements with one or more protective layers, for example, by covering the top and / or bottom with one or more further film layers. Conveniently, the capacitor is enclosed by the protective film. The protective films can be glued or laminated, for example. Although for them basically the same polymer material as for the Carrier film can be used, this is not mandatory. Thus, as protective films not only those based on polyethylene, polypropylene, polyimide or

Polyethylene terephthalate are used, but also those based on, for example, organosilicon polymers. It is also possible to apply one or more protective lacquer layers instead of or in addition to protective films. This can be useful, for example, if the film surface is also to be rendered hydrophobic or color-coded. By using coil antenna elements provided as such with protective films and / or protective lacquer as the metamaterial, the method according to the invention can also be used under conditions in which the material can be exposed to high mechanical, thermal or climatic stresses, as for example in some applications in the field of electromobility.

It is known that in inductive energy transmission by the use of metamaterial in addition to the shielding effect described above, a focus of the respective provided magnetic field can be achieved. This effect, which is sometimes referred to as "magnetic lens" can also improve the efficiency of the inductive energy transfer of a

Transformer arrangement can be used on a receiver assembly. Such

Use is possible for metamaterial e.g. in IEEE TRANSACTIONS ON MICRO W AVE THEORY AND TECHNIQUES, VOL. 64, NO.5, MAY 2016, p. 1644-1654. The article refers in particular to the fact that the high space requirement of the previously known metamaterial cells precludes their widespread use, and presents as a solution to the problem a comparatively compact arrangement in which metamaterial with

Thickness dimensions in the centimeter range in the manner of a magnetic lens in the space between the transformer and receiver coil is introduced, thus causing an improvement in the inductive energy transfer.

However, the space requirements of such metamaterials with thickness dimensions in the

Centimeter range still too high for some applications. A further object of the invention was therefore to specify a metamaterial which, with a small space requirement, focusses the magnetic field provided by the transformer arrangement

Alternating field allows and in this way further improves the inductive energy transfer to the receiver. This object is achieved by an embodiment of the method according to the invention, in which the Übertrageranordnung in their the receiving position of

A receiver facing the array has a magnetic alternating field focusing layer of metamaterial, which is formed by a plurality of identically constructed coil antenna elements, which are applied in a flat, regular arrangement on a polymer film and each comprise a coil-forming conductor tracks with integrated capacitor whose inductance and capacitance are matched to one another such that the layer has the magnetic field focusing effect at the operating frequency of the alternating magnetic field. This effect can be achieved if the operating frequency of the alternating magnetic field for the layer

Metamaterial results in an effective permeability of Ueff '<0.

An advantage of this embodiment is that it is necessary for the focusing of the

Magnetic metamaterial may be constructed analogous to the metamaterial described above for use in shielding the stray fields.

In principle, therefore, the features explained in the introduction for the screening metamaterial, e.g. in terms of production, structure, materials and the like., Analogously transferred to the metamaterial used with focusing effect. These statements made above apply mutatis mutandis to the present embodiment, so that can be dispensed with a new explanation.

However, as an essential difference from the shielding metamaterial, it should be noted that the metamaterial used with the focusing effect has the

Conductors and the capacitor with respect to inductance and capacitance are to be designed so that at the operating frequency of the alternating magnetic field an effective

Permeability with negative sign, i. Ueff '<0, preferably between -0.5 and -1, in particular between -0.8 and -1. Even in these cases, the appropriate

Design and dimensioning of the tracks and capacitors of the

Coil antenna elements advantageously determined by simulation calculations and optimized on the basis of preliminary tests.

The invention further includes a transducer assembly suitable for use in the method of the invention. Such transformer arrangements essentially have a transformer coil, which consists of a molded body of a magnetizable material is surrounded, wherein the transmitter coil is embedded in the receiving position of the Empfangeranordnung open recesses of the shaped body and the molded body is provided in its receiving position of the receiver assembly remote area at least partially with at least one shielding layer of the metamaterial. In a

According to an embodiment of the invention, the transmitter arrangement can be provided with a magnetic material-focusing layer of the metamaterial in the region facing the receiver position of the receiver arrangement. As already explained above in the method according to the invention for the metamaterial used, the flat, periodic arrangement of a multiplicity of identically constructed coil antenna elements described therein is used as the metamaterial, which are respectively constructed of conductor tracks applied to a polymer film, forming a coil, and a capacitor integrated therein , whose inductance and capacity are coordinated so that in the

Operating frequency of the alternating magnetic field for the layer of metamaterial results in a stray field shielding effect (ie an effective permeability of Ucfr '<1, preferably between 1 and 0, in particular between 0.2 and 0), and for the according to said embodiment optionally present layer from metamaterial a magnetic field focusing effect (ie an effective permeability of Ueff '<0, preferably between -0.5 and -1, in particular between -0.8 and -1). Magnetisable concrete is preferably used as the magnetizable material for the shaped body. This usually contains particles of one or more soft magnetic materials, which are preferably selected from the group of soft ferrites, the nanocrystalline metals, the amorphous metals and the metallic powder. The particles are usually incorporated into a matrix of a binder which can be used for concretes, for which advantageously solidified hydraulic cement, white cement, Portland cement or bitumen is selected. The proportion by weight of each selected soft magnetic material is favorably at least 80 weight percent, preferably 85 to 95

Weight. In some cases, however, the weight fractions up to one

Lower limit of about 60 weight percent lowered or increased to an upper limit of about 98 weight percent. The weight proportions suitable for the respective application are expediently determined with the aid of preliminary tests. As a rule, for reasons of cost, the upper limit will not exceed the value at which the magnetic saturation occurs, while the lower limit can be the value at which sufficient magnetization is still achieved. In most cases, the highest possible degree of filling of the soft magnetic material in the magnetizable concrete is desired. This can be achieved, for example, favorably, that soft magnetic materials with certain

Grain size distributions are selected to a dense packing of the

To achieve material particles. It has proven useful to present a soft magnetic material, for example a soft magnetic ferrite, in two or more particle size fractions. In particular, a first fraction with a middle

Grain diameter from 2 to 10 mm with a particle size distribution between 0.5 and 20 mm and a second fraction with a mean grain diameter of 0.1 to 0.5 mm are combined with a particle size distribution of 0.01 to 5 mm. Usually, such fractions are presented in approximately equal proportions by weight, with deviations of up to about 20 weight percent up or down can be accepted. Such combinations of different fractions of soft magnetic ferrites are

For example, from EP 1 097 463 and can according to this document for

Manufacture of magnetizable products are inter alia embedded in a matrix of hydraulic cement, which is shaped and finally solidified.

In the transformer arrangement according to the invention, the shaped body has its surface

Reception position of the receiver assembly side facing recesses, which serve to receive the transmitter coil. The recesses can, for example, in the

Frame of a casting process or by machining, e.g. Milling, grinding or cutting, as well as by joining correspondingly shaped modules are generated. The transformer coil as such will be provided in accordance with the respective one to be provided

alternating magnetic field according to the usual and known to those skilled criteria and selected according to the predetermined boundary conditions. Will the in the

Traversed by windings of the transformer coil flows through an alternating current, so forms a corresponding magnetic alternating field with a certain operating frequency. This can interact magnetically with a receiver coil brought into the reception position and thus effects an inductive energy transmission.

The occurring magnetic stray fields can be inventively significantly reduced by the fact that the molding in its receiving position of

Receptor arrangement remote area at least partially, but preferably is completely provided with a shielding layer of the invention to be used metamaterial. For example, in the case of a rectangular shaped body, a particularly effective reduction of the stray fields is achieved if all side surfaces and the base surface are covered with the metamaterial and only the surface facing the receiving position remains free of shielding metamaterial. Such

however, full coverage is not mandatory; sometimes a partial cover may be sufficient. Experience has shown that it is possible to determine through preliminary tests which base and side surfaces are to be provided with the metamaterial in order to achieve the desired reduction of stray fields.

Because of the small thickness and the correspondingly small space requirement of the

Advantageous embodiments of the transformer arrangement according to the invention can be provided which are difficult or impossible to implement with conventional metamaterials and, moreover, are often associated with high costs.

According to a first advantageous embodiment, the transformer arrangement is provided with a second shielding layer of the metamaterial, in which conductor tracks and capacitors of the coil antenna elements are matched in their inductance and capacitance to each other so that at a further, second operating frequency of the alternating magnetic field for this second layer from metamaterial gives an effective permeability Ueff '<1. This can be a simple way even then

Reduce the stray fields, when an operation of the transformer arrangement is provided at a second operating frequency of the alternating magnetic field, to which the metamaterial of the second layer is cut. In particular, this is also a

Switching between two operating frequencies possible without loss of energy due to stray fields. There are in this context, further developments of

Transformer arrangement not excluded, which are provided with further layers of the invention to be used metamaterials, which are adapted in their resonance behavior, for example, to other possible operating frequencies of the alternating magnetic field. Such developments are particularly advantageous when the transformer assemblies are permanently installed, for example, by being integrated into a roadway structure, and can be dispensed with costly and costly expansion and installation measures when changing the operating frequency. In a second advantageous embodiment, the transmitter arrangement is provided with a magnetic material-focusing layer of metamaterial in the area in the reception position of the receiver arrangement. In such a layer, as explained above, the coil antenna elements are each made of a polymer film

applied, a coil-forming conductor tracks and a capacitor integrated therein, whose inductance and capacitance are coordinated so that at the operating frequency of the alternating magnetic field for the focusing layer

Metamaterial an effective permeability with a negative sign, i. Ueff '<0 returns. Such an arrangement has the advantage that the focusing of the field, the energy transfer can be further improved without the between transformer and

Receiver arrangement available free space significantly

limit. This advantage comes especially in inductive charging of

Electric vehicles to bear, where in some variants, a transformer assembly is integrated into the road and a minimum distance to the in-vehicle

Receiver arrangement is to be observed.

Said second advantageous embodiment can also be modified such that a second focusing layer of metamaterial is provided, in which the conductor tracks and capacitors of the coil antenna elements are cut to a second possible operating frequency of the alternating magnetic field. Analogous to the

In connection with the embodiment described above, further layers of the metamaterial can also be provided, which in each case become effective at further operating frequencies for focusing the alternating magnetic field.

At times transmitter arrangements installed in the vicinity of magnetic field sensitive devices may be required to further enhance the shielding effect by providing one or more metallic shielding layers, if any. This is especially true when the

Method is operated in areas where high demands on the

electromagnetic compatibility and / or the electromagnetic environmental compatibility are made. For the implementation of the method according to the invention, in principle, the receiver arrangements customary for the respective purpose are suitable. In many cases, a receiver coil is provided in these for interaction with the magnetic alternating field provided by the transformer arrangement, by means of which, for example, an inductively transmitted charging current for a battery or an accumulator can be generated. However, such a receiver coil is not mandatory for all applications; for inductive heating or inductive heating, for example, flat metal parts may be provided for receiving the inductively transmitted power. Analogous to the embodiment described above for the transformer arrangement, the receiver arrangement may comprise a molded body of magnetizable material, in particular magnetizable concrete, which is provided with recesses open towards the receiving position, in which the receiver coil is embedded. According to a further embodiment of the invention, the receiver arrangement has a stray field shielding layer of metamaterial in its region remote from the receiving position. According to the invention, the layer is, as already described above in the method according to the invention and also suitable for carrying it out

Transformer arrangement for the metamaterial used, formed by a plurality of identically constructed coil antenna elements, which are applied in a flat, regular arrangement on a polymer film and each forming a coil

Including interconnects with integrated capacitor whose inductance and capacitance are coordinated so that the layer at the operating frequency of the alternating magnetic field has a stray field shielding effect (i.e., an effective

Permeability of Ueff '<1, preferably between 1 and 0, in particular between 0.2 and 0). The practical provision of the metamaterial takes place in the manner described in connection with the method according to the invention and the transformer arrangement and should not be repeated again for reasons of concise presentation. The inventive use of the metamaterial based on coil elements, which are applied in a flat, regular arrangement on a polymer film and each comprise a coil-forming printed conductors with integrated capacitor, can be both in the method described above, as well as in the transformer assembly and / or the receiver arrangement an improved efficiency of the inductive Achieve energy transfer. This applies equally to the use of coil elements, which are applied in a planar, regular arrangement on a polymer film and each comprise a coil-forming conductor tracks with integrated capacitor, as a metamaterial in the inductive energy transfer by means of magnetic alternating fields having a substantially constant operating frequency.

The inventive method as well as suitable for its implementation

Transformer arrangement and / or receiver arrangement can be used with particular advantage for inductive energy transfer for the purpose of static, stationary or dynamic charging of batteries in electric and / or hybrid vehicles, or for the direct drive such vehicles, or for the purpose of inductive heat generation.

The invention will be explained in more detail with reference to the figures.

FIG. 1 a schematically shows a method for inductive energy transmission in which a transformer arrangement is used which does not use metamaterial.

FIG. 1b schematically shows the otherwise identical method, in which, however, in the case of FIG

Transformer assembly in the manner according to the invention shielding metamaterial is used.

Figure 2 shows schematically the structure of a single one of the coil antenna elements, which arranged in plurality form the metamaterial used in the invention.

Figures la and lb:

In Figure la, a transformer assembly 1 is shown, which may be integrated, for example, in a roadway structure 2 and which has a molded body 3 made of magnetizable material, such as a magnetizable concrete. The molded body is provided with recesses 4, in which a transformer coil 5 is embedded with their turns. If these are flowed through by current, an alternating magnetic field 6 is formed whose course is schematically indicated by field lines. If a receiver arrangement 7, which has, for example, a receiver coil 8 and can be provided in an electrically operated vehicle not shown here, is brought into a receiving position in the region of the alternating field, the alternating field 6 enters into magnetic interaction with the receiver arrangement 7, for example by excitation the receiver coil 8, thereby causing the inductive transmission of energy. However, the efficiency of the energy transfer is affected by the fact that facing away from the receiving position Surfaces of the molding, ie its side surfaces 9 and possibly also the base 10, stray fields 11 occur.

FIG. 1b shows how, with an otherwise identical structure in the manner according to the invention, the side surfaces 9 and the base surface 10 of the molded body 3 are provided with shielding metamaterial 12, for example by gluing. In the present illustration, the thickness of the used metamaterial 12 is greatly increased for the sake of clarity; in practice, the metamaterial used according to the invention leads only to minimally increased space requirements because of its small thickness. If the metamaterial 12 has an effective permeability of Ueff '<1 at the operating frequency of the alternating magnetic field 6, then it has

shielding effect and thus causes the leakage of stray fields 11 on side and bottom surface of the molded body 3 is significantly reduced or completely prevented. Thus, the energy losses occurring by the stray fields are also minimized, and a larger proportion of the magnetic alternating field 6 provided by the transformer arrangement 1 according to the invention compared to FIG

Receiver arrangement 7 and the interaction with the receiver coil 8 are available.

FIG. 2:

FIG. 2 schematically shows the construction of one of the coil antenna elements which can be used as a meta material according to the invention as a multiplicity in a planar, periodic arrangement. The coil antenna element 14 shown here as, for example, rectangular individual element comprises a thin polymer film 15, running parallel in its outer region in the form of a rectangle with rounded corners

Printed conductors 16 applied, for example, are printed. The conductor tracks 16, which, for example, as 1-2 mm wide, at a distance of 1-2 mm from each other

Aluminum or copper tracks can be designed are connected to each other at its two end points 17 via a preferably low-volume capacitor 18. This arrangement corresponds to a resonator which can be designed in terms of its properties such that an effective permeability, which is smaller than 1 or even has a negative sign, results in a certain frequency range. This has the advantage that the desired resonance behavior of the coil antenna elements and thus of the metamaterial can be tailored precisely to the operating frequency of the alternating magnetic field. The following embodiment serves to illustrate the invention and is not to be construed as a limitation.

Exemplary embodiment:

For the provision of a transformer arrangement was made of a mixture of about 50

Mass% soft magnetic ferrite with a grain size with average grain diameter of about 5 mm, about 40 mass% soft magnetic ferrite with a grain size with average grain diameter of about 0.25 mm (determination of the mean grain diameter in each case by sieve analysis), about 5 mass - Portland cement, about 0.5 mass% of liquefier and about 4.5% by mass of water by pouring into a mold and then curing a cuboid shaped body with 75 cm in length, 55 cm wide and 2.5 cm in height

made of magnetizable concrete. The molding was provided on its upper outer surface with recesses into which a transformer coil was inserted. This was connected via leads to an inverter, via which the current for the provision of the alternating magnetic field was fed. The operating frequency of the alternating field was set to a value of 85 kHz. This value is currently envisaged in the field of electromobility as a standard based on SAE standard J 2954.

For comparison purposes, a receiver coil having the identical dimensions as the transmitter coil has now been placed in the receiving position as a receiver arrangement, i. It was positioned as close as possible to the transmitter coil at a distance of 30 cm. Using a standard vector network analyzer, it was then measured at the receiver coil what percentage of the power provided by the transmitter coil was inductively transmitted to the receiver array. This percentage was about 88%.

Subsequently, for the actual exemplary embodiment, the metamaterial to be used according to the invention was glued to the base surface as well as all side surfaces of the shaped body so that only the surface provided with the recesses remained free. For the metamaterial, 50 successively arranged rows of 10 each were arranged side by side on a 200 .mu.m thick polyethylene terephthalate film by etching according to a method customary for the production of passive RFID labels

Coil antenna elements have been generated. The individual elements each consisted of a quadrangular section of the film, on its periphery parallel to its Outside edges four parallel aluminum conductors (width about 1mm, spacing about 1.5 mm) were formed with rounded corners. The tracks ended in two round endpoints, which were connected by a flat capacitor. From the operating frequency of the alternating magnetic field of 85 kHz was determined by resonant circuit calculation, that a suitable effective permeability Ueff '<1 can be achieved with a resonator whose inductance about 5 μΗ and whose rated capacity is about 10 μ ¥. As for the provision of this capacity suitable capacitors conventional flat ceramic capacitors corresponding specification could be used. In order to provide the appropriate adjusted inductance, the tracks were designed so that each individual element gave a total length of 1.2 m.

On the provided with the thus designed conductor tracks and equipped with the capacitors surface of the polymer film was finally a protective film

Polyethylene terephthalate applied. The resulting metamaterial was cut to size and adhered to the side surfaces and the base of the molded article.

Now again the transformer coil was inserted into the recesses of the molding and connected to the inverter. Analogously to the procedure described above for comparison purposes, the receiver coil with the identical dimensions as the transmitter coil was brought into the receiving position as a receiver arrangement, i. It was positioned as close as possible to the transmitter coil at a distance of 30 cm. The

provided alternating magnetic field was operated as in the comparison arrangement with an operating frequency of 85 kHz.

With the aid of the vector network analyzer, it was again measured at the receiver coil which percentage of the power provided by the transmitter coil was inductively transmitted to the receiver arrangement. This percentage was about 93%. The inventive use of coil antenna elements, which consists of a

Polymer film applied, a coil-forming conductor tracks and a capacitor integrated therein are constructed as a metamaterial thus allows for a small space requirement and low production costs a significant improvement in the efficiency of the inductive energy transfer.

Claims

claims:

1. A method for reducing stray fields in inductive energy transmission, in which a by a transformer coil (5) containing

Transformer assembly (1) provided, a substantially constant

Operating frequency having alternating magnetic field (6) in magnetic

Interaction with a brought into a receiving position, preferably a receiver coil (8) containing receiver assembly (7) occurs, wherein the

Transducer assembly (1) in its the receiving position of the receiver assembly (7) facing away from a stray field shielding layer (12) of metamaterial, characterized in that the layer (12) of metamaterial is formed by a plurality of identically constructed coil antenna elements (14), which are applied in planar, regular arrangement on a polymer film (15) and each comprise a coil forming conductor tracks (16) with integrated capacitor (18) whose inductance and capacitance are coordinated so that the layer (12) at the operating frequency of magnetic alternating field (6) stray field has shielding effect.

2. The method according to claim 1, characterized in that the Übertrageranordnung in its the receiving position of the receiver array facing a magnetic field (6) focusing layer of metamaterial, which is formed by a plurality of identically constructed coil antenna elements (14), which in area , Regular arrangement are applied to a polymer film (15) and each comprise a coil forming printed conductors (16) with integrated capacitor (18) whose inductance and capacitance are coordinated so that the layer at the operating frequency of the alternating magnetic field (6)

Has magnetic field focusing effect.

3. The method according to claim 1 or 2, characterized in that the polymer film has a thickness of 10 μιη to 300 μπι and preferably consists of polymer based on polyethylene, polypropylene, polyimide or polyethylene terephthalate, and / or

that the conductor tracks are made of conductive material based on aluminum, copper, silver or conductive polymers, and or

that the coil antenna elements are designed as a rectangle, trapezoid, square, hexagon or circle and their number is at least 4.

4. The method according to one or more of claims 1 to 3, characterized in that the operating frequency of the alternating magnetic field with an accuracy of at least + 5%, preferably at least ± 2%, more preferably + 1% is maintained.

5. transformer assembly (1) for carrying out the method according to one or more of claims 1 to 4, which contains a transformer coil (5), of a

Mold body (3) is surrounded by a magnetizable material, wherein the transformer coil (5) in the receiving position of the receiver assembly (7) open towards recesses (4) of the molded body (3) is embedded and the shaped body (3) in its receiving position of the receiver assembly (7) is provided at least partially with at least one stray field shielding layer (12) of the metamaterial and optionally in the receiving position of the receiver assembly (7) facing region with a magnetic field (6) focusing layer of metamaterial is provided, each layer from metamaterial by a plurality of identically constructed Spulenantennen- elements (14) is formed, which are applied in a flat, regular arrangement on a polymer film (15) and each comprise a coil-forming conductor tracks (16) with integrated capacitor (18) whose inductance and capacity are coordinated so that the Schich t (12) from metamaterial at the

Operating frequency of the alternating magnetic field (6) stray field has shielding effect and optionally present layer of metamaterial has the magnetic field focusing effect.

6. transformer assembly according to claim 5, characterized in that the shaped body (3) consists of magnetizable concrete, wherein the magnetizable concrete contains particles of one or more soft magnetic materials which are selected from the group of soft ferrites, the nanocrystalline metals, the amorphous metals and the metallic powder, and these are incorporated into a matrix of one for concretes usable binder selected from the group of solidified hydraulic cement, white cement, Portland cement or bitumen.

7. transformer arrangement according to claim 5 or 6, characterized in that a second stray fields shielding and optionally a second magnetic field focusing layer are provided from the metamaterial, in which the conductor tracks and the capacitor of the respective coil antenna elements are matched in their inductance and capacitance to each other in that its stray fields shielding and optionally the magnetic field focusing effect occurs at a second operating frequency of the alternating magnetic field.

8. receiver arrangement (7) for carrying out the method according to one or more of claims 1 to 4, which in its receiving position remote area has a stray field shielding layer of metamaterial, which is formed by a plurality of identically constructed coil antenna elements (14) are applied in a planar, regular arrangement on a polymer film (15) and each comprise a coil forming printed conductors (16) with integrated capacitor (18) whose inductance and capacitance are coordinated so that the layer (12) at the operating frequency of the magnetic Alternating field (6) stray field has shielding effect.

9. Use of coil antenna elements (14), which are applied in a flat, regular arrangement on a polymer film (15) and each comprise a coil-forming conductor tracks (16) with integrated capacitor (18), as

Metamaterial in a method according to one or more of claims 1 to 4, in a transformer arrangement (1) according to one or more of claims 5 to 7 or in a receiver arrangement according to claim 8.

10. Use of the method according to one or more of claims 1 to 4, a transformer assembly (1) according to one or more of claims 5 to 7 or a receiver assembly according to claim 8 for inductive energy transfer for the purpose of static, stationary or dynamic charging of batteries in electric and / or hybrid vehicles, or for the direct drive of such vehicles, or for the purpose of inductive heat generation.

11. Use of coil antenna elements (14), which are applied in a flat, regular arrangement on a polymer film (15) and each comprise a coil forming printed conductors (16) with integrated capacitor (18), as a metamaterial in the inductive energy transmission by means of magnetic

Alternating fields having a substantially constant operating frequency.