DE102013217728A1 - coil assembly - Google Patents

Abstract

The invention relates to a coil arrangement (10), in particular for a charging device for the wireless energy - technical coupling of a power source, with a coil (14) having a connection surface (12), which coil (14) has a winding (18) and a plurality of turns (16) a ferromagnetic body (20) at least partially encompassed by the winding (18), at least a portion of the winding (18) providing the bonding surface (12), the coil assembly (10) engaging the ferromagnetic body (20). thermally coupled heat conducting element (22), which terminates substantially flush with the connecting surface (12).

Description

The present invention relates to a coil arrangement, in particular for a charging device for wireless energy-related coupling of a power source, having a coil having a connection surface, which coil has a multi-turn winding and a ferromagnetic body, which is at least partially surrounded by the winding, wherein at least one Area of the winding provides the connection surface. The invention further relates to an electrically drivable vehicle having a drive device which comprises an electric machine, an electrical energy store for supplying the electric machine with electrical energy in a driving operation of the vehicle and a charging device for supplying electrical energy to the electrical energy store. Furthermore, the invention relates to a charging station for an electrically driven vehicle, with a connection for an electrical energy source, a converter and a converter connected to the coil arrangement for wireless energy technology coupling a charging device of the electrically driven vehicle to supply energy to the vehicle.

Charging devices for wireless energy-related coupling of an energy source are basically known, so that it does not require a separate documentary evidence for this. An electrical device, for example an electrically drivable vehicle, has a charging device so that energy can be supplied to the device, in particular the vehicle, which is stored in an energy store of the device or of the vehicle for the purpose of carrying out an intended operation. The energy is usually provided by means of a charging station, which in turn is connected to an electrical energy source, for example to a public power grid, to an electric generator or the like.

One way of supplying the energy from the charging station to the charging device is that an electrical connection is made by means of a cable between the device and the charging station. In addition, it is known, according to another possibility to produce a wireless energy technology coupling, which avoids a complex mechanical connection by means of cable. For this purpose, a coil arrangement is generally provided on the charging station side and the device side, in each case, which are arranged opposite one another and which enable an energy-technological coupling using an alternating magnetic field. Such an arrangement is for example from the KR 10 2012 0 016 521 A known.

In order to form the power engineering coupling as low as possible, the coils usually have ferrites, by means of which the magnetic alternating field can be performed to improve the energy technology coupling. In certain coil designs, the ferrite of the device-side or vehicle-side coil is heavily loaded in the energy transfer by means of the alternating magnetic field due to a high magnetic flux density. The high magnetic flux density causes a correspondingly high power loss in the ferrite. This power loss causes a high temperature stress of the ferrite, which can affect its physical properties. It is therefore desirable to keep the temperature stress of the ferrite as low as possible.

This results in the object of the invention to provide a coil assembly and an electrically driven vehicle and a charging station, in which the temperature stress of the ferrite can be reduced.

As a solution, a coil arrangement according to the independent claim 1 is proposed with the invention. On the vehicle side, an electrically drivable vehicle according to the further independent claim 11 is proposed. Finally, a charging station according to the further independent claim 12 is proposed on the charging station side. Further advantageous embodiments of the invention will become apparent from the dependent claims.

Energy-technical coupling in the sense of the invention is a coupling for the purpose of transmitting energy, which makes it possible to transmit energy from an energy source to an energy sink, at least unidirectionally. But it can also be provided a bidirectional energy transfer, that is, an energy transfer alternately in both directions. Among other things, this purpose is served by the charging station, which receives its energy, which is to be transmitted to the device or the electrically driven vehicle, from an energy source to which it is electrically connected.

Wireless energy-technical coupling in the sense of the invention means that between the charging station and the device, in particular the electrically driven vehicle, no mechanical connection needs to be provided for the production of the electrical coupling. In particular, the production of an electrical connection by means of a cable can be avoided. Instead, the energy-related coupling essentially takes place solely due to an energy field, preferably an alternating magnetic field.

The charging station is therefore configured to generate a corresponding energy field, in particular a magnetic alternating field. On the device side or on the vehicle side, it is correspondingly provided that such an energy field or alternating magnetic field can be detected and energy is derived therefrom for the intended operation of the device or of the electrically drivable vehicle. The energy is converted by means of a charging device into an electrical energy, which can then preferably be stored in an energy store of the device or the vehicle for its intended operation. The energy-technical coupling thus essentially serves the transmission of energy and not primarily the transmission of information. Accordingly, the means for carrying out the invention are designed for a correspondingly high power throughput in contrast to a wireless communication link.

An essential element for a wireless energy technology coupling, in particular by means of an alternating magnetic field, is the coil arrangement comprising at least one coil, occasionally also a plurality of coils, the device side or vehicle side of the energy field, in particular the magnetic flux in an alternating magnetic field as an energy field flooded and provide electrical power at their respective terminals. Accordingly, the coil arrangement is electrically charged with an alternating current on the charging station side so that the coil arrangement provides a magnetic alternating field by means of its coil or coils. About the magnetic alternating field, the coil assembly of the charging station is coupled to the coil assembly of the device or the electrically driven vehicle.

In general, the coil has a winding with a plurality of turns of an electrical conductor, wherein the winding usually includes or encloses a ferromagnetic body, which is often formed by a ferrite. By means of the ferrite, the magnetic flux can be guided in the desired manner, so that the effectiveness of the magnetic coupling between the coil arrangements of the charging station and the device or of the electrically driven vehicle can be enhanced. In principle, however, the ferromagnetic body can also be formed from another material which has the greatest possible magnetic permeability and the lowest possible electrical conductivity. Frequently, the ferromagnetic body extends at least along the winding, occasionally also protruding beyond the winding. The turns of the winding are preferably wound around the ferromagnetic body and insulated from each other and formed opposite to the ferromagnetic body.

The mounting of the coil usually provides that a connection surface is formed, which allows to fix the coil to a holding device. In coils for generic coil arrangements, a connection surface is usually provided by the winding. For the intended use cooling of the coil takes place at least partially via the connecting surface and the holding device. The connection surface is preferably defined by a plane defined by an outer side of the electrical conductor of the winding in its position or at least partially formed by the outside of the electrical conductor itself. The bonding area may also be determined by a shape of a conductor cross-section of the conductor. The bonding surface may also be at least partially defined or formed by an outer circumference of the winding.

In particular with an encapsulated coil arrangement, the essential cooling of the coil can be provided via the connection surface. Often a direct thermal coupling of the ferromagnetic body for the purpose of cooling is not possible. It is therefore provided according to one aspect of the invention that a thermally coupled to the ferromagnetic body heat conduction is provided, which is substantially flush with the connection surface. For this purpose, the ferromagnetic body is not covered by the winding of the coil at least in a region, so that the heat-conducting element can be attached. Preferably, a plurality of areas not covered by the winding are provided, so that correspondingly many heat-conducting elements can be provided. This makes it possible to significantly improve the thermal coupling of the ferromagnetic body to the heat sink, namely the holding device, which is connected to the connection surface. The temperature stress of the ferromagnetic body can therefore be significantly reduced.

The heat-conducting element can be designed, for example, as a heat-conducting pad and be formed from a thermally highly conductive material. Preferably, the heat-conducting element is designed to be electrically insulating. Suitable materials include, for example, alumina, but also thermally highly conductive plastics, composites and / or the like in question. Preferably, the heat-conducting element is designed such that it forms the connection surface together with the winding. The Connecting surface thus also forms the surface over which the heat from the coil can be derived. Therefore, the holding device is preferably designed accordingly, so that it makes possible thermal contact with the entire connecting surface. In this way it is possible to achieve a good cooling or heat dissipation from the coil.

According to a further aspect, it is proposed that the heat-conducting element is arranged between two adjacent turns. For this purpose, the adjacent turns are spaced apart from each other, so that a space is created in which the heat-conducting element can be arranged. Of course, a plurality of turns spaced from each other can be arranged, between each of which a heat conducting element can be arranged. Thereby, the heat dissipation from the ferromagnetic body can be further improved.

According to a further aspect of the invention it is proposed that the windings contact the ferromagnetic body, in particular are arranged thermally contacting and together with the heat-conducting element form the connecting surface. The windings can contact the ferromagnetic body completely or partially. Preferably, a substantially continuous, in particular closed connection surface is created. The heat-conducting elements preferably have a height dimension substantially corresponding to a diameter of the electrical conductor forming the turns of the winding. It proves to be particularly advantageous if the electrical conductor has a rectangular cross-sectional shape, and the cross-sectional shape of the heat-conducting element is adapted accordingly in order to form a connection surface that is as homogeneous as possible. When using a high-frequency strand as an electrical conductor, the conductor can also be adapted by shaping in the desired manner.

The turns forming the electrical conductor is often formed as a so-called Hochfrequenzlitze, that is, it consists of a plurality of mutually electrically insulated individual conductors, which are summarized forming the conductor. This ensures that in frequency applications, a current displacement effect is reduced or substantially avoided.

If the conductor forming the windings of the winding is formed by a high-frequency strand, it can additionally be achieved with the invention that ferrite-side strand sections of the conductor are cooled via the ferromagnetic body and the heat-conducting elements. This is particularly advantageous because in the case of strands, the thermal conductivity across the electrical conductivity is reduced due to the insulation of the individual strands and, as a result, ohmic losses of a single strand can only be dissipated from the conductor formed by the strands with poor thermal coupling. As a result, the invention can also provide improved cooling of a high frequency strand forming the electrical conductor.

A development of the invention proposes that the heat-conducting elements substantially fill the spaces between the adjacent turns. Thus, it can be achieved that not only the ferromagnetic body itself is thermally improved coupled, but also complementary to the turns of the winding forming electrical conductor. As a result, the coil can be cooled better overall and thus is more resilient. In addition, the coil can thereby be constructed more compact, so that construction volume and weight can be saved.

A further aspect of the invention provides that the connection surface can be thermally coupled to a heat sink. For this purpose, the connecting surface is substantially flat, so that a good thermal coupling to the heat sink, for example, the holding device can be achieved. For this purpose, the connecting surface may further be provided with a heat transfer reducing surface structure, for example with an elasticity that allows to compensate for unevenness of the surface and the heat sink to be coupled and to allow a good thermal connection.

According to a further aspect, it is proposed that the coil has a substantially cuboid shape and the mounting surface is formed by one of the cuboid surfaces. This makes it possible to achieve a compact construction and at the same time be able to achieve a simple thermal coupling with a large connection area. At least one of the two largest opposite surfaces of the cuboid are particularly advantageous as connecting surfaces. At the same time is achieved with this design of the coil, that by design already a flat connection surface is provided, which is particularly simple and inexpensive to couple thermally.

An advantageous development of the invention provides that a heat conducting layer is applied to the connecting surface. The heat-conducting layer can be formed, for example, in the form of a heat-conducting foil, an applied thermal paste, an applied thermal-adhesive, combinations thereof and / or the like. Particularly advantageously, the heat conducting layer is formed with such a formability that it unevenness, Pores, surface structures and the like for good thermal coupling can compensate. Thereby, the thermal coupling can be further improved and further a temperature gradient in the plane of the connection surface can be further reduced.

According to a further aspect of the invention, the coil arrangement has a housing in which the coil is arranged. The coil assembly can be protected in this way from external influences. In addition, an easily manageable unit can be created by the housing. The housing is preferably formed of an electrically non-conductive material. In addition, the housing is preferably formed from a non-ferromagnetic material. It can thereby be achieved that the housing essentially does not influence the function of the coil arrangement.

A further development provides that the connecting surface is thermally conductively connected to a housing cover of the housing. The housing cover thus provides the heat sink which serves to cool the coil assembly. For this purpose, the housing cover may have a different material than the rest of the housing. Thus, the housing cover may for example be formed of a metal, but also of a thermally highly conductive ceramic material, such as alumina and / or the like. Thus, the housing cover, for example, copper, aluminum, alloys thereof and / or the like may be formed. Preferably, the housing cover on the housing side has a contact surface which is adapted to the connection surface and allows a good thermal and mechanical coupling of the coil to the housing cover. If the mounting surface is a surface of a coil formed in cuboidal shape, then the housing cover is preferably formed by a metal sheet, a flat plate or the like which at least reaches, preferably exceeds, the dimensions of the connecting surface. This makes it possible to connect the housing cover in a simple manner with the housing at the edge regions such that the coil arrangement can be enclosed by the housing.

On the vehicle side, it is proposed with respect to the electrically driven vehicle that the charging device for wireless energy-related coupling of a power source has a coil arrangement of the invention. In the case of the electrically drivable vehicle, the charge device serves to convert energy supplied to the vehicle into electrical energy in such a way that it can be stored in the energy store of the vehicle for its intended operation. The same applies to applications in devices in general and for the charging station according to the invention.

Thermal coupling in the context of the invention means that a very small thermal resistance is achieved by a combination of two bodies, so that a temperature gradient between the thermally coupled bodies is as low as possible. Preferably, it is provided for this purpose that the bodies touch each other mechanically and a surface structure in the area of the contact is as smooth as possible or permits a transfer of large amounts of heat at low or small temperature gradients.

Further advantages and features will be apparent from the following description of an embodiment with reference to a FIG. In the FIG identical components and functions are designated by the same reference numerals.

The single FIGURE shows a schematic cross-section of a coil arrangement 10 according to the invention. The coil arrangement 10 is present component of a charging device for wireless energy technology coupling a power source of an electrically driven vehicle, which is not shown in the FIG. The coil arrangement 10 has a connection surface 12 having coil 14 on which coil 14 a several turns 16 having winding 18 and a ferromagnetic body 20 made of ferrite.

The ferrite 20 is from the winding 18 completely encompassed by the turns 16 the winding 18 around the ferrite 20 wrapped around and these are arranged mechanically contacting. The in the FIG above the ferrite 20 arranged turns 16 make the connection area 12 ready. With the interface 12 becomes the coil 14 both thermally and mechanically coupled.

From the FIG is not apparent that the turns 16 the winding 18 forming electrical conductor is formed from a high-frequency strand, which is formed from a plurality of individual, mutually insulated wires or strands and which shows due to their structure in normal operation substantially no current displacement effect. The use of such a Hochfrequenzlitze is useful in the intended use of the coil assembly, since the energy technology coupling is done by means of an alternating magnetic field whose frequency in the range of a few hundred Hertz up to a few kilohertz, for example in the range of 25 to 200 kHz, preferably in one area from 130 to 140 kHz, or even in a range of about 85 kHz, or the like. So one As even current distribution on the individual wires of the strand can be achieved, a twisting of the individual wires is usually provided. The twisting may also include forming bundles of a certain number of the individual wires which are twisted in themselves and these bundles, forming the electrical conductor, are also twisted.

In the FIG, the conductor is the turns 16 the winding 18 forms, provided with a round cross-section. The individual turns 16 the winding 18 are spatially spaced from each other so that adjacent turns 16 rooms 24 form. In these rooms 24 are thermal pads 22 arranged as Wärmeleitelemente having a substantially cuboidal structure and with one of its surfaces on the ferrite 20 issue. As a result, they are thermal with the ferrite 20 coupled. In order to achieve the best possible heat transfer, it can be provided that the heat-conducting 22 Ferrite side are provided with a heat transfer reducing coating. This coating may be formed, for example, by thermal paste, thermal adhesive or the like.

From the FIG is also apparent that the heat conducting pads 22 have a height h, which is essentially the small radius of the turns 16 forming electrical conductor, so that it connects to the connection surface 12 essentially flush. The turns 16 and the thermal pads 22 thus form a connecting surface 12 ,

In a further embodiment, it may additionally be provided that the turns 16 forming electrical conductor has a rectangular cross-section and has a height equal to the height h of the Wärmeleitpads 22 equivalent. This allows a substantially decided flat surface as a connection surface 12 be formed.

The coil shown in FIG 14 has a substantially cuboid shape and the connection surface 12 is formed by one of the cuboid surfaces. This is the ferrite 20 formed as a plate which is formed by a plurality of strips, as can be seen from the FIG. The thermal pads 22 are formed by strips of material between each adjacent turns 16 are arranged. A transverse to the sectional plane in the FIG extending extension of the ferrites 20 and the thermal pads 22 is essentially the same. This ensures that the ferrite can be thermally relieved of its extension.

From the FIG it can also be seen that on the connecting surface 12 another Wärmeleitschicht 26 is formed, the present also as Wärmeleitpad 26 is trained. The thermal pad 26 may be formed by a thermal conductive film, such as a plastic film or the like. The thermal pad 26 is preferably by a continuous, over the entire connection surface 12 extending element formed, for example, by gluing or the like to the windings 16 and / or the Wärmeleitpads 22 can be coupled. As a result, on the one hand, a mechanical and, on the other hand, a thermal connection can be achieved. The thermal pad 26 In addition, it can ensure that a temperature gradient in the interface 12 can be reduced.

From the FIG is further apparent that the coil 14 in a housing cover 28 and a housing cup 30 comprehensive housing is arranged. The case mug 30 In the present case, it is formed from a plastic which on the one hand has a low electrical conductivity and, on the other hand, a low magnetic permeability. In contrast, the housing cover 28 in the present case formed from a metal, for example aluminum or copper or an alloy thereof. The housing cover 28 is with the housing cup 30 connectable such that the housing formed thereby the coil 14 completely protects against mechanical and atmospheric influences.

It can also be seen from the FIG. That the coil is in the state installed in the housing with the heat-conducting pad 26 the housing cover 28 contacted mechanically. As a result, a good thermal connection is ensured at the same time, so that heat over the housing cover 28 can be removed from the coil. The housing cover 28 acts in this sense as a heat sink, which is why the connecting surface 12 for thermal coupling of the housing cover 28 is designed as a heat sink. The housing cover 28 is in turn attached to a cooling device, not shown, of the electrically driven vehicle, so that the heat from the coil assembly 10 can be dissipated.

As can be seen from the exemplary embodiment, the invention enables a full-surface thermal connection of the ferrite 20 to the housing 28 . 30 to improve. For this purpose, the gaps of the turns formed by the strand winding 16 with the strip-shaped Wärmeleitpads 22 filled. The thermal pads 22 close flush with the height of the high frequency strand of the turns 16 from. To get a good heat transfer from the high-frequency strand of the windings 16 or the Wärmeleitpads 22 to the housing cover 28 In addition, a substantially full-surface thin Wärmeleitpad is complemented 26 hung up.

With these measures, a favorable heat path can be realized and the power dissipation occurring in the ferrite can be dissipated over this.

The foregoing description of the embodiment is intended only to illustrate the invention and not limit it. Of course, those skilled in the art will provide appropriate variations as needed without departing from the spirit of the invention. In particular, individual features can be combined as needed in any way with each other.

In addition, of course device features can be realized by corresponding method steps and vice versa.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• KR 1020120016521 A [0003]

Claims (12)

Coil arrangement ( 10 ), in particular for a charging device for wireless energy-related coupling of a power source, with a connection surface ( 12 ) having coil ( 14 ), which coil ( 14 ) a several turns ( 16 ) winding ( 18 ) and a ferromagnetic body ( 20 ) of the winding ( 18 ) is at least partially included, wherein at least a portion of the winding ( 18 ) the connection surface ( 12 ), characterized by a to the ferromagnetic body ( 20 ) thermally coupled heat conducting element ( 22 ) connected to the interface ( 12 ) substantially flush. Coil arrangement according to Claim 1, characterized in that the heat-conducting element ( 22 ) between two adjacent turns ( 16 ) is arranged. Coil arrangement according to Claim 1 or 2, characterized in that the turns ( 16 ) the ferromagnetic body ( 20 ) are arranged in contact and together with the heat-conducting element ( 22 ) the connection surface ( 12 ) form. Coil arrangement according to one of Claims 1 to 3, characterized in that adjacent windings ( 16 ) are arranged spaced from each other and each have a heat conducting element ( 22 ) between two adjacent turns ( 16 ) is arranged. Coil arrangement according to Claim 4, characterized in that the heat-conducting elements ( 22 ) Rooms ( 24 ) between the adjacent turns ( 16 ). Coil arrangement according to one of claims 1 to 5, characterized in that the connecting surface ( 12 ) is designed for thermal coupling of a heat sink. Coil arrangement according to one of Claims 1 to 6, characterized in that the coil ( 14 ) has a substantially cuboid shape and the connecting surface ( 12 ) is formed by one of the cuboid surfaces. Coil arrangement according to one of claims 1 to 7, characterized in that on the connecting surface ( 12 ) a heat conducting layer ( 26 ) is applied. Coil arrangement according to one of Claims 1 to 8, characterized by a housing ( 28 . 30 ), in which the coil ( 14 ) is arranged. Coil arrangement according to claim 9, characterized in that the connecting surface ( 12 ) with a housing cover ( 28 ) of the housing ( 28 . 30 ) is thermally conductively connected. Electrically drivable vehicle having a drive device, which comprises an electric machine, an electrical energy store for supplying the electric machine with electrical energy in a driving operation of the vehicle and a charging device for supplying electrical energy to the electrical energy store, characterized in that the charging device for wireless power engineering Coupling a power source to a coil assembly ( 10 ) according to one of the preceding claims. Charging station for an electrically driven vehicle, having a connection for an electrical energy source, a converter and a coil arrangement connected to the converter for wireless energy-related coupling of a charging device of the electrically driven vehicle in order to supply energy to the vehicle, characterized in that the coil arrangement ( 10 ) is designed according to one of claims 1 to 10.

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