Antenna arrangement for inductive energy transmission and use of the antenna arrangement

Translation of description of equivalent WO 2005112192 A1

Description ÄNTENNENANORDNUNG FOR INDUCTIVE ENERGY TRANSFER AND USE OF THE ANTENNA ARRANGEMENT

The invention relates to an antenna arrangement with an open magnetic core and a winding.

The invention is in the field of used for inductive energy transfer magnetic antennas. In principle, it is possible to transmit energy and information by means of electric or magnetic dipoles. In this case, electromagnetic waves, or even Ü predominantly electrical or magnetic fields are generated depending on the driving circuit. It may be desirable, zustrahlen no electromagnetic waves off, but being limited to the generation of magnetic fields in order to avoid, for example, the effect on organic tissue in the aerial environment. In particular, relatively high energies without a galvanic coupling can be transmitted by the radiation of magnetic fields or the inductive coupling to a magnetic antenna. The effect of such a coupling is smaller on a narrow spatial area than about the limits. Nevertheless, a variety of applications for such a transfer result.

In principle, most of the known soft magnetic powder composites can be used here as pressed magnet cores alongside common soft ferrites. For example, these consist of iron powder. With such magnetic cores is effective permeabilities between 10 and 30 can be achieved. According achievable saturation inductions are about 1.0 to 1.4 T. There also are powder composites of soft magnetic crystalline Iron-aluminum-silicon alloys and iron-nickel alloys are known which use frequencies can be up to about 100 kHz achieved.

The disadvantage of such composite materials and ferrites is that the pressing technologies allow only simple geometric shapes and that the resulting magnetic cores are relatively brittle and susceptible to breakage. In addition, the corresponding magnetic properties are highly temperature dependent, which complicates the use of resonant circuits.

DE 19846781 Al magnetic cores are known which are produced by injection molding of an injection-mouldable plastic and a nanocrystalline alloy.

Corresponding nanocrystalline alloys are known for example from EP 0271657 A2 and EP 0455113 A2. Such alloys are, for example, by means of Rascherstar- improvement technology in the form of thin alloy ribbons manufactured that are initially amorphous and which are subjected to heat treatment for formation of a nanocrystalline structure. Such alloys can be ground to alloy powders smaller than 2mm in particle sizes. Preferably, so-called flakes formed with thicknesses from 0.01 to 0.04 mm and widths or lengths of 0.04 to

1mm per particle. These flakes can be processed by means of synthetic resins for composites, in which saturation magnetization can be realized more than 0.5 Tesla and permeabilities between 10 and 200. A production method for such magnetic cores, for example, shown in 0191141 AI WO. From EP 0762535 AI antennas for transponders are known which are also made of soft magnetic powder composites, such as amorphous alloys. Such antennas are used there to exchange information. This leads to the fail-safe operation of the exchange of information in a spatial region of a few meters, and low susceptibility to metal objects in the environment to antenna.

The present invention is, however, the object of providing an antenna arrangement for use in the inductive transmission of energy.

The present invention is directed attention to the effective energy transmission in the near field and the reliable functioning independently of a precise positioning of the antenna arrangement with respect to a receiver to which the E nergy to be transferred inductively through. To this end, the setting of very specific magnetic properties, in particular a sufficient flow with suitable exhaust is radiation characteristics necessary for the antenna array.

It is to be transmitted from a transmitter to one receiver nem over a distance between about 0.5 and 50 cm by means of a generic antenna assembly services between about 1 and 100W. Application examples are all devices that need to be wirelessly temporarily or permanently energized. It is because of the inductive coupling only a frequency range of 10 kHz to 150 kHz because of the availability of this frequency band and the Di ene sionierungsrandbedingungen particularly suitable. In addition, a magnetic flux of at least 20 μWb in the magnetic core to realize. Since such antennas, such as those used in the present antenna assembly, mostly representing the inductive part of the resonant circuit, is to optimize the energy gieabstrahlung high quality antenna of at least 50, preferably even 100 in the range of operating frequency is desirable. In addition, a temperature-independent permeability is required, which is the optimum flux guidance between 30 and 200. At higher permeability the flow bundling is basically so good that side, too low a flux component exiting the core and the field strength along the core, that is, in the receiver area is highly inhomogeneous.

The task underlying the present invention is based, can not be satisfactorily resolved with the known magnetic devices, magnetic cores and materials.

It is achieved by an arrangement according to claim 1 and a use of such an arrangement according to entitlement. 13 Refinements and developments of the invention are the subject matter of dependent claims.

According to the invention, the magnetic core as a composite material, a soft magnetic component of finely divided particles and a plastic component, wherein the magnetic core has an initial permeability between 20 and 200 and a saturation induction> 0.6 T.

The soft magnetic component is advantageously made of the aforementioned flakes of a nanocrystalline material. This has a saturation magnetization of about 1 to 1.6T and permeabilities> 30,000. By mixing with a plastic component of the magnetic circuit is formed by interrupted the microscopic gaps between the flakes and it can be lower effective permeabilities of 30 to 100 at a high quality and temperature stability adjust. Nevertheless, a high flux density achievable yields greater than 0.6 T, also typically greater than 0.9 T. The soft magnetic component of the magnetic core also has advantageously the property that the particles berflächenschicht individually by one O are electrically isolated. This can be realized for example by 'surface oxidation or plastic coating. The particle size can advantageously less than 2 mm, respectively, wherein the particle thicknesses may be less than 0.5mm. This configuration of the particles particularly low hysteresis losses and therefore a particularly high quality of the antenna are away.The mechanical properties are relative depending on the type and proportion of the plastic used in the fracture toughness and flexibility, as well as their dependence on temperature adjustable.

The plastic component can all generally within the

Gießharztechnologie processable thermoplastic or thermosetting plastics, such as polyamide, polyacrylate, polyacetal, polyimide, or epoxy resin may be selected depending on the desired mechanical and thermal properties.

In the simplest case, the antenna array as a magnetic core a rod or plate which are provided with a winding. There are certain core cross sections necessary to make the arrangement for the effective transfer of energy used. Set in a central core

Flow of at least 20 μWb be achieved, then an induction of 400 mT results in a cross section of 0.5 cm², This corresponds to about half the cross-section which would be necessary with the use of a soft ferrite.

It should, to view the magnetic core to increase the flow ef- fectively can, the coil length of the coil be greater than their diameter, preferably large compared to the diameter. An essential characteristic of the material used in the invention is the mechanical resistance to shock or vibration and the free shaping as part of the preparation or subsequent flexibility. The material used in the invention allows for its magnetic properties also small in size, as is desirable for cost, space and design reasons, in many applications.

To realize the desired radiation or flux guide of the antenna arrangement, it may be advantageous that several coils are arranged on the same magnetic core, wherein the longitudinal axes of the coils at an angle> 0 °, for example 90 ° to each other. The windings can be driven simultaneously or alternately out of phase in order to reach the receiver of the inductive energy transfer in different positions. Characterized the energy transfer more reliable and as to the relative positioning of transmitter and receiver is sensitive. The invention also refers to various operating processes of the antenna device according to the invention with intermittent operation of the various windings or the aforementioned phase-shifted simultaneous control of the different windings.

In order to achieve such an increased acceptance in the positioning of transmitter and receiver, it is also conceivable bar that several windings are provided on various magnetic cores of the type mentioned, wherein the emission characteristic of individual magnetic cores is shaped differently or aligned. This measure is the optimal positioning of a receiver of the transmitted energy increases.

Since the antenna assembly according to the invention is also geared to be space-saving, it may additionally be sensible to provide a recess within a magnetic core, in the electronic components such as the drive circuit of the antenna array, can be accommodated. The flow guide within the magnetic core is hardly affected negatively by such recesses when they are not too large. In addition, the antenna array can be prefabricated advantageous to the driving circuit and simply used as an integral unit in a device.

The invention is explained in greater detail using the exemplary embodiments illustrated in the drawing figures. It shows:

1 shows a plate-shaped rectangular configuration of a magnetic core with a winding,

Figure 2 shows a corresponding magnetic core with two windings,

Figure 3 is a stabför strength magnetic core with a winding,

Figure 4 is a bar-shaped magnetic core with an integrated coil and pole pieces, 5 shows a magnetic core with a recess and

Figure 6 is an application of the antenna arrangement with two magnetic cores.

1 shows a sheet-like magnetic core 1 with a He winding 2, wherein the dimensions of the magnetic core, for example, 20 x 10 x may be 0.2 cm. The base of the core is preferably as large as the target to be covered space of a receiver. Due to the configuration of the winding, for example, a compaction of the turns towards to the winding ends, one above the core surface as homogeneous as possible strong flux density is generated. For special design of the flow direction and the radiation in the figure 2 one ne combination of two perpendicular windings 3.4 on a running nearly as square plate magnetic core 5. The two coils can be alternately in succession or simultaneously against each driven phase.

With a suitable choice of the plastic component, the entire arrangement according to Figure 1 or 2 may be flexible. But in any case it is less sensitive than break, for example, an antenna with a ferrite core or a core of other usual materials.

Particularly suitable for the transmission of energy to a moving receiver, the arrangement shown in Figure 3 with a rod-shaped magnetic core, the direction of movement, as well as the antenna of the receiver is directed parallel to the longitudinal axis 6 of the winding 7th 6 shows two different magnetic cores 8, 9 are shown, each having a separate winding and whose longitudinal axes are perpendicular to each other to enable various flux densities and emission characteristics. This is an alternative embodiment to that shown in Figure 2 shown with a plurality of windings on a single magnetic core.

4 shows an arrangement in which the winding 10 is integrated into a magnetic body 11 in so far as the

Magnetic core 11 itself passes through, so that a lower portion of the magnetic core 11 in the Figure 4 forming a yoke that short-circuits the magnetic flux on the bottom. This and the pole pieces 12, 13 a shielding effect in a direction (downward) is achieved in still good upward stray.

For preparing such an arrangement, the casting process is illustrated in WO 0191141 AI particularly suitable, in which the winding may be cast in the manufacture of the magnetic core with.

5 shows in the magnetic core 14 has a recess 15, which allows there components of an electronic circuit, for example, to drive the winding 16, accommodate.

6 shows an example of use of the antenna assembly of the invention device with a mobile Kommunikationsendge-, for example, a mobile phone or a cordless phone 17 that has a non-illustrated receiving means for inductive coupling to the antenna array 18th The antenna assembly 18 includes a GE housing 19, the two magnetic cores on 8, 9, which are each provided with a winding and can inductively transmitted energy to the receiver in the terminal 17th In the terminal 17, a capacitor or rechargeable battery for storage of the transmitted energy is provided in addition to the receiver.

Despite the specialization of the antenna arrangement described in the transfer of energy, the same arrangement also for retransmission of information, or a sig- may Nals serve that is either also transmitted inductively, üsste are being switched between transmission and reception, or by evaluating the energy drain of the receiver ,

It is also the practice of the invention in the transfer of energy from a mobile device imaginable to a stationary device, for example in railway technology for transmitting signals and / or energy from a fixed to a vehicle device to a stationary sensor in a control room / a signal box for traffic monitoring.