The invention relates to method of manufacturing a winding structure unit of a primary unit or a secondary unit of a system for inductive power transfer, in particular to a vehicle. Further, the invention relates to such a winding structure unit.

Document WO2014/037324 A3 discloses a pavement slab assembly for a route for vehicles, wherein the pavement slab assembly comprises a cable bearing element adapted to position and/or to hold a plurality of line sections of one or more electric lines, wherein the electric line or lines are arranged in the cable bearing element and the cable bearing element is embedded in the pavement material of the pavement slab assembly.

The document WO2014/027373 A1 discloses a cable bearing element adapted to position and/or to hold at least one line a section of an electric line. This cable bearing element is made of a thermoplastic material.

The document DE 10 2017 101 583 A1 discloses a receiving device of a system for inductive power transfer with a housing, wherein a winding structure is arranged within an inner volume of the housing.

The documents disclose to arrange the electric line or electric lines of a winding structure in a so - called cable bearing element which provides mechanical stability to the winding structure such that its geometric design is secured during operation. However, these cable bearing elements add cost and building space requirements to a winding structure unit.

There is the technical problem of providing a method of manufacturing a winding structure unit and such a winding structure unit of a primary unit or secondary unit of a system for inductive power transfer, wherein a weight of the winding structure unit and building space requirements are reduced although a desired mechanical stability of the geometric design of the winding structure is provided over the lifespan.

The solution to said technical problem is provided by the subject-matter with the features of claim 1 and claim 13. Further advantageous embodiments provided by the subject- matter with the features of sub claims. Proposed is a method of manufacturing a winding structure unit. The winding structure unit can denote an entity comprising a winding structure. The winding structure can be provided by or comprise at least one electric line or more than one, in particular three electric lines for a three phase system. Moreover, the entity can comprise material embedding or encasing the electric line(s). The winding structure unit can also be referred to as winding structure block.

The winding structure unit can be part of a primary unit or a secondary unit of a system for inductive power transfer, in particular to a vehicle. Said inductive power transfer is performed using two sets of windings, in particular single-phase windings. A first set is installed on the ground (primary winding structure) and can be fed by a wayside power converter (WPC). The second set of windings (secondary winding structure) is installed on the vehicle. For example, the second set of windings can be attached underneath the vehicle, in the case of trams under some of its wagons. For an automobile it can be attached to the vehicle chassis. The second set of windings or, generally, the secondary side is often referred to as pick-up-arrangement or receiver. The first set of windings and the second set of windings form a high frequency transformer to transfer electric energy to the vehicle. This can be done in a static state (when there is no movement of the vehicle) and in a dynamic state (when the vehicle moves).

The primary unit can comprise all elements which are required to generate the

electromagnetic field for inductive power transfer, in particular to a vehicle. More particular, the primary unit can comprise a housing, wherein at least one of said elements, in particular the primary winding structure, is arranged within the housing. The secondary unit can comprise all elements which are required to receive the electromagnetic field for inductive power transfer, in particular to provide a rectified DC output voltage generated from the AC voltage induced in the secondary winding structure. More particular, the secondary unit can comprise a housing, wherein at least one of said elements, in particular the secondary winding structure, is arranged within the housing.

The winding structure can be a primary winding structure for generating an

electromagnetic field for inductive power transfer from a primary unit to a secondary unit, wherein the secondary unit can be arranged on a vehicle. Alternatively, the winding structure can be a secondary winding structure for receiving an electromagnetic field (generated by a primary winding structure) and for generating an alternating current output voltage. A primary winding structure can e.g. comprise at least three electric lines and at least one winding structure per electric line. A secondary winding structure can e.g. comprise at least one electric line. An electric line can be provided by a winding structure or a vice versa.

The present invention can be applied in particular to the field of energy transfer to any land vehicle, for example track bound vehicles, such a rail vehicles (e.g. trams). Further, the invention relates to the field of energy transfer to road automobiles, such as individual (private) passenger cars or public transport vehicles (e.g. buses). The winding structure can provide a primary winding structure or a secondary winding structure of the system for inductive power transfer. The winding structure comprises a main winding structure with a first sub-winding and at least another sub-winding. A sub-winding can comprise one or more section(s) of a phase line of the main winding structure. The main winding structure can comprise one or more phase lines for carrying an electric current, e.g. three phase lines. A sub-winding can enclose a predetermined area. Also, a sub-winding can provide or form a coil, e.g. with a predetermined number of turns.

Within the method, in particular in a first step, a casting mold is provided. The casting mold is used to receive the at least one electric line of the winding structure and casting material. In other words, the casting mold can have a receiving volume for receiving the winding structure and the casting material.

The casting mold can be designed and/or configured such that a desired geometry of the winding structure unit is provided, in particular after casting material which is casted into the casting mold is cured. The casting mold can have multiple elements, in particular a bottom element and a cover element. These elements can enclose the receiving volume. The casting mold can allow a series production of multiple winding structure units.

Further, in particular in a second step, at least one electric line is arranged within the casting mold. The at least one electric line can e.g. be provided by a braid. The at least one electric line can provide a phase line of the winding structure. Further, it is possible that the at least one electric line is arranged within the casting mold in a predetermined geometric design. The at least one electric line can be an electrically insulated or a non- insulated line. It is possible that the casting mold is adapted to position and/or to hold at least one line section of the at least one electric line, in particular such that the predetermined geometric design of the winding structure is provided. It is e.g. possible that the casting mold provides at least one guiding channel for the section the at least one electric line.

Further, in particular in a third step, at least one additional mechanical element is arranged within the casting mold, in particular within the receiving volume of the casting mold. The at least one additional mechanical element can, as will be explained later, be a fastening element for fastening the winding structure unit to a carrying structure or a reinforcement element of the winding structure unit. The at least one additional mechanical element can be arranged at predetermined location within the casting mold, e.g. within its receiving volume, in particular such that the winding structure unit comprises the at least one additional mechanical element at a predetermined location and or with predetermined orientation after casting material has been cured. It is possible that a casting mold is adapted to position and/or to hold the at least one additional mechanical element. In particular, the casting mold can provide fixation means for the at least one additional mechanical element. The at least one additional element can be made of a non- magnetic material, in particular made of plastic.

Further, in particular in a fourth step, a casting material is casted into the casting mold, in particular into the receiving volume of the casting mold in which the at least one electric line and at least a part of the additional mechanical element is arranged. Casting the casting material into the casting mold can be performed under a vacuum. The casting material can be a resin, in particular an injection resin.

The casting material can be casted into the casting mold such that at least the electric line (s) are fully coated or covered by the casting material. Further, at least a section portion of the or the complete additional mechanical element can be fully or partially coated or covered by the casting material. Further, the casting material can be casted such that the electric lines and the additional mechanical elements are glued together.

Further, in particular in a fifth step, the casting mold can be removed. The casting mold can be removed after the casting material has been cured. After removal of the casting mold, the winding structure unit is provided by the cured entity comprising the cured casting material, the at least one additional mechanical element and the at least one electric line.

Due to the cured casting material, a predetermined geometric design of the at least one electric line is secured in a stable manner. Since no additional cable bearing element is needed, manufacturing costs and building space requirements are advantageously reduced.

As the casting mold can allow a series production, it can be assured that the mechanical shape of the winding structure unit is kept the same in such a series production of the winding units, with the advantages of keeping same inductance of the system. Forming windings with same inductance is the greatest advantage for a resonant wireless charging system.

In another embodiment, the at least one electric line is arranged with a desired geometric design. This advantageously allows to generate an electromagnetic field with desired, predetermined characteristic for inductive power transfer or to receive an electromagnetic field with a predetermined way, in particular with a predetermined effectivity.

The at least one phase line of the primary winding structure can be designed such that a course of the phase line provides an even or uneven number of sub-windings which are arranged adjacent to each other. In this context, a sub-winding can denote a, preferably complete, conductor loop which encloses a predetermined area. The conductor loop can provide or comprise one turn or multiple turns of the respective sub-winding. Adjacent to each other means that central axes of the sub-windings, in particular the axes of symmetry, are spaced apart from one another, e.g. with the predetermined distance, along the common straight line. The common straight line can be parallel to a longitudinal axis of a reference coordinate system and can correspond to a direction of extension of the primary winding structure. This means that a phase line of the primary winding structure can extend in a direction of extension, wherein a predetermined number of sub- windings is provided along said direction of extension.

Neighboring or adjacent sub-windings can be counter-oriented. In this context, counter- oriented can mean that a current flow in a first sub-winding is oriented clockwise, wherein the current flow in the neighboring or adjacent second sub-winding is oriented counter- clockwise. The clockwise direction can be defined with respect to the parallel central axes which point into the same direction. If a current flows through the said of sub-windings, adjacent sub-windings can generate a magnetic field of the same magnitude but oriented in opposite directions. In such a winding structure configuration, electromagnetic forces can be generated in the windings. The proposed method advantageously allows securing the configuration such that it withstands thermal stress, mechanical weight and vibration and electromagnetic forces together.

Preferably, the winding structure can be 8-shaped. This can mean that a course of the at least one phase line is 8-shaped. In this case, the phase line can comprise two e.g.

circular-shaped or rectangular-shaped sub-windings which are arranged adjacent to each other along the direction of extension according to the aforementioned explanation. In this case, the main winding structure can also be referred to as double

D-winding structure.

Preferably, the primary winding structure can comprise three phase lines, wherein each phase line can comprise or provide multiple, in particular two, sub-windings which extend along a common direction of extension.

Alternatively, a phase line of a winding structure can have a meandering course. In this context“meandering” means that the phase line of the primary winding structure extends along a track or route in a meandering manner, i.e. sections of an electric line which provides the phase line which extend in a longitudinal direction of the winding structure are followed in the course of the conductor by section which extends transversely to the longitudinal direction (i.e. in a lateral direction of the winding structure). In the case of a multiphase system with at least two electric phase lines, this preferably applies to all the phase lines.

In another embodiment, the at least one additional mechanical element is a fastening element for fastening the wining structure unit to a carrying structure. The carrying structure can be a carrying structure provided by a primary unit or provided by a secondary unit. The carrying structure can in particular be a housing for the winding structure. It is possible that the fastening element is designed as a threaded bar or an element providing a thread or a through hole. The fastening element can e.g. be configured, e.g. designed and/or arranged, such that a force-fitting and/or form-locking mechanical connection to the carrying structure can be provided. Further, the fastening element can be configured such that a detachable mechanical connection to the carrying structure can be provided.

This advantageously allows to provide a winding structure unit which can be easily installed in a primary unit or in a secondary unit.

In another embodiment, the at least one additional mechanical element is a reinforcement element for the winding structure unit. The reinforcement element can be configured, e.g. arranged and/or designed, such that the mechanical stability of the winding structure unit with said reinforcement element is higher than a winding structure unit without such a reinforcement element. This advantageously provides a high mechanical stability.

In another embodiment, the reinforcement element is provided as grid or a mat. The reinforcement element can be fully or partially covered or coated by the casting material. Providing the reinforcement element as a grid or a mat allows to provide a very high mechanical stability of the resulting winding structure unit.

In another embodiment, the at least one additional element is a thermal coupling element for providing a thermal connection between the winding structure and an external or exterior volume. The thermal coupling element can be an element for transferring thermal energy. The thermal coupling element can e.g. be made of ceramics. This advantageously allows to transfer thermal energy from the winding structure unit, in particular the at least one electric line, to the external volume and thus increases an operational safety of the winding structure unit.

In another embodiment, the at least one additional mechanical element is a magnetic flux guiding element. The magnetic flux guiding element can be made of a magnetic material.

It advantageously allows to provide a desired course of a magnetic flux which leads to a more efficient inductive power transfer.

It is also possible that the at least one additional mechanical element is an electric insulation element which can e.g. be arranged between the at least one electric line and a further electric or electrically conductive element. The insulation element can have a C- shape, wherein the at least one electric line can be arranged at least partially or fully within the volume enclosed by the C-shaped insulation element.

In another embodiment a first quantity of casting material is casted into the casting mold. Further, a second quantity of casting material is applied to the first quantity of casting material after the first quantity is cured. It is e.g. possible that a second quantity of casting material is casted into the casting mold after the first quantity is cured, in particular fully or to a certain extend but not fully. It is also possible to remove the casting mold after the first quantity is cured and then apply the second quantity. It is further possible to remove the casting mold after the first quantity is cured and to arrange the winding structure unit in a further casting mold and then apply the second quantity, e.g. by casting the second quantity into the further casting mold. After the second quantity has been applied, in particular cured, it is possible to remove the further casting mold.

A casting material of the first quantity can be the same casting material as the casting material of the second quantity. It is, however, also possible that the casting material of the second quantity is different from the casting material of the first quantity.

Applying casting material in two steps advantageously allows to adjust characteristics of the resulting winding structure unit, in particular mechanical characteristics, in a broader range.

In another embodiment, the at least one additional element is arranged within the casting mold before the second quantity of casting material is applied. In particular, the at least one additional element can be arranged within the winding structure unit, in particular within the casting mold or further casting mold, after the first quantity of casting material has been casted into the casting mold. This advantageously allows to provide a stable arrangement of the additional element during the application of the second quantity since it is possible to fully cure the first quantity wherein the additional element can be arranged at least partially within first quantity of casting material. Thus, the additional element is fixed within the first quantity.

In another embodiment, the at least one additional element is arranged within the casting mold before the first quantity of casting material has been cured, in particular such that the additional element is at least partially coated or covered by the first quantity of casting material. This advantageously allows a flexible and thus easy-to-provide arrangement of the additional element within the first quantity.

In another embodiment, a first quantity of casting material is casted into the casting mold such that at least a section of the electric line is fully or at least partially covered by a ribbed structure of the casting material. It is e.g. possible that the casting mold in particular an element such as a bottom and/or cover element of the casting mold is configured e.g. designed and/or arranged, such that the first quantity provides a ribbed structure after curing. The ribbed structure can e.g. be provided at external surfaces of the cured casting material. The ribbed structure can e.g. comprise or provide a layer of casting material with a varying thickness. The thickness can vary stepwise or gradually. Providing a ribbed structure advantageously increases mechanical stability of the winding structure unit. A distance between two adjacent rib sections along a direction of extension of the electric line can be chosen application-dependent.

In another embodiment, a thickness of section of the ribbed structure which provides rib is equal to or higher than half the minimal isolation distance between the electric line and a further electric or electrically conductive element. Said minimal isolation distance can be an application-dependent distance, e.g. a distance smaller than 1 mm. It can e.g. be determined depending on characteristics of the at least one electric line and/or characteristic of operating parameters, e.g. the current and/or voltage provided to the at least one electric line. A rib can e.g. be provided by a protruding section of a layer of the first quantity of casting material covering or coating the at least one electric line. A rib can e.g. have the form of a bar. The bar can e.g. have a rectangular cross section area in a cross section plain perpendicular to a central access of the bar.

The thickness of said section can e.g. depend on the material used and the voltage difference between the electric line and the electric element between which the ribbed structure is arranged. If the voltage difference is small, e.g. if the electric line and the further electric element are part of the same (sub)winding, the thickness can be smaller than in the case that the electric line and the further electric element are part of the different (sub)windings. In another embodiment, a distance between two adjacent rib sections along a direction of extension of the electric line is chosen such that the at least one electric line does not plunge into a deepening with said width, in particular if the at least one electric line extends across the deepening.

It is, for instance, possible that the casting mold, in particular a bottom element and/or a cover element of the casting mold, has at least one deepening which, when casting material is casted into the deepenings, provide a rib section of the ribbed structure. By choosing the aforementioned width of such a deepening, it is advantageously avoided that the geometry of the electric line changes due to plunging into said deepenings before or during casting material is casted into the casting mold.

Further, a distance or gap can be provided between two adjacent rip sections along the direction of extension of the at least one electric line. Said distance or width of such a gap can be chosen depending on the size of the winding structure.

Further, the quantity of casting material can be applied such that the gaps between two rip sections are partially or fully filled by the casting material of the second quantity. More particular, the second quantity of casting material can be applied such that a layer with a constant thickness, e.g. in the range of 1 mm to 14 mm, in particular in the range of 1 mm to 3 mm or 7 mm to 14 mm, more particular with a thickness of 2 mm, covers or coats the at least one electric line. The thickness can be chosen application-dependent.

This advantageously increases a mechanical stability and also provides an improved operational safety of the winding structure unit since the electric lines are fully enclosed by an insulation layer with constant thickness provided by the first and the second quantity of casting material.

Further proposed a winding structure unit of a primary unit or a secondary unit of a system for inductive power transfer, in particular to a vehicle. The winding structure unit is obtainable by a method according to one of the embodiments disclosed in this disclosure.

One characteristic of the resulting winding structure which is obtainable, in particular directly obtainable, by the said method is that the winding structure unit comprises a block of cured casting material, at least one electric line which it at least partially or fully embedded within the casting material, in particular with a desired geometric design, and at least one additional mechanical element which is also at least partially embedded within the casting material. A further characteristic can be the presence of two quantities of casting materials, more particular the presence of a ribbed structure.

This in corresponding advantages have been disclosed before.

In another embodiment the winding structure comprises two layers of casting material.

This and corresponding advantages have been disclosed before. The two layers can be made of the same casting material or made of different casting materials.

In another embodiment at least one layer of casting material has ribbed structure. This and corresponding advantages have been disclosed before.

In another embodiment at least one additional mechanical element is at least partially casted within the casting material. This and corresponding advantages have been disclosed before.

The invention will be disclosed with reference to the attached figures. The figures show:

Fig. 1 a schematic flow diagram of a method according to the invention and

Fig. 2 a schematic longitudinal section of winding structure unit according to the invention.

In the following, the same reference numerals denote elements with the same or similar technical features.

Fig. 1 shows a schematic flow diagram of a method of manufacturing a winding structure unit 1 (see Fig. 2) according to the invention. The winding structure unit 1 can be a sub unit of a primary unit or a secondary unit of a system for inductive power transfer, in particular to a vehicle.

In a first step S1 , a casting mold is provided. The casting mold can e.g. be provided by plastic element(s). The casting mold can be designed for series production of the same winding structure geometry. The casting mold can have different elements, in particular a bottom element and a cover element. The casting mold can be designed such that a geometric design of the winding structure unit 1 , in particular of a first quantity of casting material and/or of a second quantity of casting material, is provided if said casting material(s) which is casted into the casting mold is/are cured.

In a second step S2, at least one electric line 2, in particular in form of a braid, is arranged within the casting mold. The at least one electric line 2 can be configured or provided with a predetermined geometric design. The geometric design can be chosen depending on desired characteristics of an electromagnetic field which is to be generated by the winding structure or which is to be received by the winding structure. The casting mold can be designed such that it determines a geometric shape of the winding structure provided by the at least one electric line 2.

In third step S3 at least one additional element is arranged within the casting mold. The at least one additional element can be a fastening element for fastening the winding structure unit 1 to a carrying structure. Alternatively or in addition a reinforcement element for the winding structure unit 1 can be arranged within the casting mold as an additional element. Further additionally or alternatively a thermal coupling element for providing a thermal connection between the winding structure and an external volume can be arranged within the casting mold as an additional element. The additional element can be arranged within the casting mold before casting material 7, 8 is casted into the casting mold or after first quantity of casting material 7, 8 is casted into the casting mold.

In a fourth step S4 casting material 7, 8, in particular injection resin, is casted into the casting mold.

The fourth step can comprise two sub steps. In first sub step, a first quantity of casting material 7 is casted into the casting mold. In a second step a second quantity of casting material 8 is applied to the first quantity of casting material 7. This can e.g. be performed after the first quantity has been fully cured or not fully but to a certain extend. The second quantity can e.g. be casted into the casting mold or into a further casting mold, wherein the arrangement comprising the electric line 2, the at least one additional element and the first quantity of casting material 7 is removed from the casting mold and arranged in the further casting mold.

The casting mold can e.g. be designed such that the first quantity of casting material 7 provides a ribbed structure of casting material 7 around the at least one electric line 2 after curing. In other words, a ribbed structure can cover the at least one electric line 2 after casting of the first quantity.

Then, a second quantity of casting material 8 can be applied to first quantity of casting material 7, in particular after that first quantity has been cured. The second quantity has e.g. be applied such that recesses of the ribbed structures are fully filled by the second quantity and/or such that an isolation layer of constant thickness is provided around the electric line 2 by the combination of the first and second quantity of casting material 7, 8.

In a fifth step S5 the casting mold or the further casting mold can be removed. The fifth step S5 can e.g. be performed after the casting material 7, 8, in particular the second quantity of casting material 8 is cured. The fifth step S5 can be an optional or a mandatory step of the method.

Fig. 2 shows a schematic longitudinal section of a winding structure unit 1 according to the invention. Shown is an electric line 2 which is provided by a braid. Further shown is a first layer 3 of casting material 7 in particular injection raisin, which coats or covers the electric line 2. The first layer 3 of casting material 7 can be provided by first quantity of casting material.

Further shown is a second layer 4 of casting material 8, wherein the second layer 4 can be provided by second quantity of casting material 8. The casting material 7 of the first quantity can be equal to or different from the casting material 8 of the first quantity.

Further shown is that the first layer 3 has a ribbed structure. In particular shown are rib sections 5 which have a rectangular cross section. A thickness D5 of a rib section is chosen such that it is equal to or higher than half of a minimal isolation distance between the electric line 2 and a further electric element, in particular a further electric line 2 of the winding structure. Further shown is that a width B5 of rib section which is chosen such that the at least one additional electric line 2 does not plunge into a deepening with said width B5 if the electric line 2 is laid across such a deepening. Further shown is that the second quantity of casting material 8 fills the recesses 6 between two adjacent rib structures fully and additionally covers the rib sections 5. Further indicated is a thickness D of a resulting coating layer of the electric line 2 which comprises the casting materials 7, 8 of the first quantity and the second quantity and also the ribbed structure of the first layer 3. The thickness D can e.g. be equal 2 mm.