NO20141391A1 - Device and method for wireless transmission of power and communication - Google Patents

Abstract

The invention relates to a device for wireless transmission of power and communication. The device comprises: i) a ferrite-enclosing substrate (12) having a first side (12s1) and a second side (12s2) opposite the first side; ii) a first wireless power transmission coil (14), wherein the first coil (14) is arranged at the first side (12s1) of the ferrite-enclosing substrate (12), wherein the first coil (14) encloses a center region (14c), and iii) a first wireless communication channel (15, 15-1), the first communication channel (15, 15-1) being arranged in the center region (14c) within the first coil (14). The first coil (14) and the communication channel (15, 15-1) have been attached to the first side (12s1) of the substrate (12) using a molding process.

Description

DEVICE AND METHOD FOR WIRELESS TRANSMISSION OF POWER AND COMMUNICATION

The invention relates to a device for wireless transmission of power and communication. The invention further relates to a method for producing such a device. Such a device can be used for the transmission of energy and communications through air, water, plastic, glass, oil and other materials that are not electrically conductive. The device can also be used for transmission through non-magnetic electrically conductive materials when operating power and communication in the frequency range 1-50 kHz. The control signal can then be sent from the secondary side to the primary side by letting the secondary side modulate the amplitude of the switching signal. More specifically, the invention relates to a device for transmitting power and communication, where the device comprises a primary component and a secondary component arranged at a distance from each other, and where each of the primary component and the secondary component comprises a base (or substrate), which is at least partially arranged in a material comprising ferrite, where the arrangement further comprises an energy source and a control electronics connected at least to the primary component, and a feedback electronics and load connected at least to the secondary component. The electronics enable regulation of the energy transfer.

By connecting control electronics, energy source, feedback electronics and load to both the primary and secondary components, transfer of energy can be achieved in both directions. This can be useful in implementations of an inductive battery where both charging and discharging take place via the same component.

Wireless inductive transfer of energy is a known technology, and is used, among other things, to operate equipment and to forward measurement results in situations where transmission through cables or conventional connectors is impractical, impossible and/or dangerous. Wireless transmission of power to operate equipment is generally supplemented by wireless transmission of data communication to operate the equipment and return measurement results, etc. Transmission of communication and power is usually done by means of two separate transmission devices, which can record a lot of space. Known technical solutions are generally not so flexible with regard to the geometric shapes of the components used for the wireless transmission of power and data, and the components are furthermore usually vulnerable to external influences in such a way that they cannot be used in situations where they are exposed to mechanical shocks and/or high pressure.

Patent publication JP 2007142081 A discloses a component for transmitting wireless power comprising a coil, a core and a shield element, where the core and the shield element are arranged as an integrated unit by molding a magnetic powder and a resin binder.

Patent publication JP 2006156714 relates to a method for producing a core for a component for transmitting electrical signals, where the core is molded by mixing a magnetic powder and synthetic resin.

In patent publication US 2008061733 Al, a battery charger is described, where the battery charger comprises a coil for wireless transmission of energy, where the coil is placed in a groove in a material made of a synthetic resin and a ferrite powder.

In a similar manner, patent publication US 201248878 A1 describes a battery pack comprising a coil for contactless energy transfer, where the coil is molded in a structure made of a molding substance comprising ferrite in fine particles and a resin.

Patent publication NO 320439 Bl, corresponding to US 8125208 B2, has been submitted by the present applicant and relates to efficient wireless transmission of energy.

The purpose of the invention is to remedy or to reduce at least one of the disadvantages of known technology, or at least to provide a useful alternative to known technology.

The purpose is achieved by features that are specified in the description below and in the subsequent requirements.

The invention is set out in the independent patent claims. The dependent claims set forth advantageous embodiments of the invention.

In a first aspect, the invention relates to a device for wireless transmission of power and communication. The device comprises: a ferrite-comprising substrate having a first side and a second side opposite the first side;

a first coil for wireless power transmission, wherein the first coil is disposed at the first side of the ferrite-comprising substrate, wherein the first coil encloses a center region, and

a first communication channel for wireless communication, where the first communication channel is arranged in the center area inside the first coil, where the first coil and the communication channel have been attached to the first side of the substrate using a mold casting process.

The effects of the combination of features according to the invention are as follows. By arranging the first communication channel inside the center area of the first coil, and by subsequent molding of said assembly into a single molding layer, a very compact and very robust device is achieved. Simulations show that objects placed in the center area of the first coil and the amount of ferrite in this area do not have a major influence on the coupling factor between two components. This area has a low concentration of magnetic fields during transmission of power, and thus less noise will be absorbed in this area. This makes this area ideal for implementing communication channels. By choosing a mold casting process for manufacturing said device, it is possible to start with the coil and effectively build said device in successive layers. After molding of the first coil and the first communication channel, the ferrite-comprising substrate can be suitably arranged on a backside of the single molding layer comprising the coil and the communication channel. It must be emphasized that the first coil and the first communication channel need not be oriented in a flat orientation. The coil can, for example, also be shaped to follow a cylindrical structure, cone structure or dome structure. Regardless of which mold is chosen, it is only important to choose a mold with a shape that matches the shape of the coil and the communication channel. It must be emphasized that the requirements are only directed at one of the primary and secondary components of a communication/transmission system. It must be understood that the invention can be used on both sides or on only one of said sides in said communication/transmission systems. This means that the invention can be used on the primary side, the secondary side or both.

In an embodiment of the device according to the invention, the first coil and the communication channel have been molded in a single molding layer on the first side of the substrate.

An embodiment of the device in accordance with the invention further comprises a second communication channel for wireless communication, where the second communication channel is arranged in the center area inside the first coil. In the event that a further communication channel is to be implemented, such communication channel can suitably be placed within the same center area as the first communication channel.

In an embodiment of the device in accordance with the invention, the second communication channel is arranged in a further center area inside the first communication channel. In the event that the first communication channel is shaped like a coil which is, for example, oriented concentrically with respect to the first coil, the second communication channel can be arranged inside a further center area delimited by the first communication channel.

In an embodiment of the device in accordance with the invention, the device comprises a through hole which extends through the substrate. In embodiments where the first coil and the communication channel are arranged as concentric coils, a through hole may be provided within the further center region as in this embodiment, which may suitably be used for the provision of other components such as mechanical shafts, cables or communication channels.

In an embodiment of the device according to the invention, the first coil is at least partially buried in the ferrite-comprising substrate. Simulations have shown that burying the first coil and/or said communication channel partially within the ferrite-comprising substrate increased the coupling between the primary coil/communication channel and the secondary coil/communication channel.

In an embodiment of a device in accordance with the invention, the ferrite-comprising substrate comprises a mixture of resin and ferrite powder. By using a relatively thin molding substance, a homogeneous mixture with high ferrite contents can be achieved. The mixing ratio can be approximately one part molding substance to four parts ferrite powder. Such a composition will provide good transfer properties and the desired homogeneity. Molding with ferrite powder is a production-friendly process, which does not require expensive tools or molds with high precision, while at the same time the process allows for the molding of complex shapes such as planar, cylindrical or cone-shaped bases (or substrates). Shaping the coil and ferrite is typically done to achieve a higher coupling between the primary side and the secondary side.

In an embodiment of the device in accordance with the invention, the ferrite-comprising substrate comprises one part molding compound per four parts ferrite powder.

In an embodiment of the device according to the invention, the substrate is provided with two or more parts with different ferrite concentrations. By adjusting the mixing ratio for ferrite and molding substance, and thus grading the ferrite concentration in the base, the magnetic field can be focused.

In an embodiment of the device according to the invention, the ferrite concentration in the substrate in a part close to the coil is lower than the ferrite concentration in a part further away from the coil. In this embodiment, the transmission distance can be increased while the highly concentrated ferrite material acts as a screen for the magnetic field. A person skilled in the art will know that a lower concentration of ferrite will result in the flux lines being emitted in a wider manner, allowing greater transmission distances across an air gap between the primary and secondary components.

If the power transfer coil is at least partially molded in the ferrite material, this can provide an increased connection between the coil and the base and result in an increased induction in

the coil, so that the coil can be supplied with a lower number of windings, and thus can be produced at a lower cost. Lower number of windings also reduces the losses in the coil and reduces the generation of heat. Cables for transmission of power and/or communication can also be completely or partially molded into the base, which will provide a

robust connection to the coil and the communication channel. In one embodiment, the part of the coil and the communication channel that is not surrounded by the ferrite material can be molded in a resin. This will provide very good protection against shocks and short circuits, and it will make the device more resistant to pressure. The device can thus, for example, be used underwater, for example at a seabed in connection with the search for and extraction of hydrocarbons.

In an embodiment of the device in accordance with the invention, the device further comprises a capacitor connected in series with the first coil.

In one embodiment of the device according to the invention, the communication channel is connected to a frequency filter. The frequency filter will make it possible to use only one pair of cables for the transmission of communication and power. The filter, which may be of a type known per se, may have a cut-off frequency in the range between the switching frequency for transmitting power and the one or more frequencies used for transmitting communication, so that only communication signals can be transmitted to and from the communication channel. As an alternative or in addition, a band stop filter can be integrated in the control electronics to filter out interference in the frequency ranges that the communication channel uses for transmission.

Both high-frequency and low-frequency communication channels can be implemented on a printed circuit board. The low frequency communication channel can be provided as windings implemented as contact lines on a printed circuit board. The inductance of the windings can be adapted to a desired communication frequency. The contact lines will be able to function as an inductive coupling where the inductance is adapted to the desired communication frequency for different communication components that one wishes to tie together, which will be known to the person skilled in the art. The inductance can be adapted using separate components or by forming the contact lines on the printer circuit board.

The high frequency communication channel can be provided as a contact line or contact plate implemented on a printed circuit board. The contact lines or contact surfaces will

be able to function as a capacitive coupling where the impedance is adapted to the desired communication frequency for different communication components that one wishes to tie together, which will be known to the person skilled in the art. The impedance can be adapted using separate components or by forming the lines on the printer circuit board.

The transmission of communication can thus either be of a low-frequency type or of a high-frequency type, or both.

Alternatively, the channel for transmitting communication may be provided as a coil of wire independent of a printed circuit board.

In a second aspect, the invention relates to a method for manufacturing the device according to any of the preceding claims. The method comprises: arranging the first coil and the first communication channel in a mold;

attaching the first coil and the communication channel to the ferrite-comprising substrate using a mold casting process. The advantages and effects of the method for manufacturing the device according to the invention are closely linked with those of the device itself. Nevertheless, some additional advantages will be mentioned with respect to the embodiments.

In an embodiment of the method according to the invention, the ferrite-comprising substrate is also formed with a mold casting process. A die-casting process is a very flexible way of forming the ferrite-comprising substrate. Ferrite powder is suitably mixed with resin before it is cast in the mold. More details of the method and its embodiments will be provided in the detailed description of the figures.

In an embodiment of the method according to the invention, the step of fixing and the step of forming the ferrite-comprising substrate are done in the same mold casting process. This embodiment is very advantageous, because a mold for the mold casting process can be effectively reused in the process, i.e. the method according to this embodiment has fewer method steps and will therefore be cheaper.

In an alternative embodiment of the method according to the invention, the ferrite-comprising substrate is attached (glued, taped or attached by other similar methods) to the first coil and the first communication channel. The advantage of this embodiment is that it makes the process cheaper.

An embodiment of the method in accordance with the invention further comprises a step of providing a mechanical pressure barrier layer on the ferrite-comprising substrate. Some applications require a pressure barrier layer to provide the required specifications dictated by the application.

In a third aspect, the invention relates to a system for wireless transmission of power and communication comprising a device in accordance with the invention. The invention may be used on the primary side, on the secondary side or both. The latter forms an advantageous embodiment of the invention. Consequently, wherever in this description it says "primary side" this can be replaced by "secondary side", and vice versa. Quite often in two-way communication and/or transmission, it is quite arbitrary to define which side is primary and which side is secondary.

The following describes an example of a preferred embodiment illustrated in the accompanying drawings, where: Fig. 1 shows, viewed from above, a primary component of a device in accordance with the present invention; Fig. 2 shows, in perspective, the primary component of Fig. 1; Fig. 3 shows, seen from the side, a device in accordance with the present plan invention; Fig. 4 shows, seen from the side, a cross-section of two components in accordance with the present invention; Fig. 5 shows, seen from the side, differently shaped bases, which are used in an device ning in accordance with the present invention; Fig. 6 shows, seen from the side, an embodiment of a primary component of a device according to the present invention; Fig. 7 shows, seen from the side, another embodiment of a primary component of a device in accordance with the present invention; Fig. 8 shows, seen from the side, a further embodiment of a primary component nent of a device in accordance with the present invention; and Fig. 9 shows, seen from the side, an embodiment of a primary component in sam answer with the present invention. Fig. 10 illustrates, with a ground plan and a cross-sectional view from the side, a step forward the procedure for manufacturing the device according to the invention; Fig. 11 illustrates, with a ground plan and a cross-sectional view from the side, a further step in the method for manufacturing the device according to the invention; Fig. 12 illustrates, with a ground plan and a cross-sectional view from the side, yet another step in the method for manufacturing the device according to the invention, and Fig. 13 illustrates a cross-sectional view from the side of another embodiment of the method for manufacturing in accordance with the invention.

It should be pointed out that the above embodiments and those discussed below illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between brackets shall not be interpreted as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those set forth in a claim. The article "a" or "an" before an element does not exclude the presence of a plurality of such elements. In the device requirement that lists several means, several of these means can be given concrete form by one and the same item of hardware. The mere fact that certain measures are listed in mutually different dependent claims does not indicate that a combination of these measures cannot be advantageously used.

Hereinafter, reference number 1 denotes a device for transmitting power and communication in accordance with the present invention, as shown in fig. 3 and 4. The figures are shown schematically and simplified, and the same reference numbers refer to the same or similar elements. Electronic components connected to the device 1, both on the primary side and the secondary side, are considered to be known in the art, and for reasons of simplicity are not shown in the drawings. The device 1 for transmitting power and communication in accordance with the present invention comprises a primary component 11 and a secondary component 13. In most of the figures, only the primary component 11 is shown. Figure 1 shows a primary component 11 comprising a base 12 (this the element is also referred to as substrate in this description), where a coil 14 for inductive transmission of wireless power is arranged. In the embodiment shown, the base 12 is provided with a circular cross-section with a hole 25 in the middle. The coil 14, which is arranged concentrically around the hole in the base 12, may be partially molded into the base 12, as described in the general part of this application. The primary component 11 further comprises a channel 15 for the transmission of communication, hereinafter referred to as a communication channel 15. The communication channel 15 is formed with a smaller diameter than the coil 14, and is concentric with this around the hole 25 in the base 12. The base 12 is in the smallest partially provided in a ferrite-comprising material 121. Figure 2 shows the same primary component 11 seen in perspective, where it can be seen that the base 12 is shaped like a short cylinder. Figure 3 shows a device 1 in accordance with the present invention. The primary component 11 is arranged at a distance A from the secondary component 13. The distance A is defined from the distance between the coils 14 of the primary component 11 and the secondary component 13. Figure 4 shows a cross section from the side of the device 11 and the device 13 in accordance with the present invention. On the left side of the figure, a cable 20a is shown which connects the coil 14 on the primary component 11 with a control electronics and an energy source (not shown), which can be a frequency controllable power supply, while the coil 14 on the secondary component 13 can be connected to a feedback electronics and load (not shown). Reference is made to the above-mentioned patent publication NO 320439 B1, corresponding to US 8125208 B2, for a more detailed description of the technology. To the right of the figure, a cable 20b is shown, which for example connects the communication channel 15 to a communication electronics not shown. The figure also illustrates the hole 25 as discussed with reference to fig. 1. Figure 5 shows bases 12 provided with alternative geometries. Molding with ferrite powder and mixed with a resin, such as epoxy or polyurethane, gives great flexibility, and thus gives access to forming bases of almost any geometry. The figures show bases with conical shapes and cylindrical shapes.

In fig. 6 shows an embodiment of a primary component 11 where a capacitor 16 is connected in series with the coil 14. A more detailed description of this can be found in said patent publication NO 320439 B1, corresponding to US 8125208 B2. The capacitor 16 will move the resonance segment away from the not shown control electronics and to the coil 14 in the base 12. Since capacitor 16 is connected in series with an inductor 14 will form a voltage resonance circuit, the embodiment shown will allow the potentially high voltage part of the system, the control electronics (not shown) are moved away, thus making it easier to meet the safety requirements, and it reduces the requirements for voltage isolation for the cable and connectors. Figure 7 shows an embodiment of the primary component 11 with a frequency filter 17 integrated with the communication channel 15. The frequency filter 17, which can be of a type known per se, has a cut-off frequency in the range between the switching frequency for transmitting power and the one or more frequencies used for the transmission of communication, so that only communication signals are transmitted to and from the communication channel 15. This allows the use of a common cable for the transmission of communication and power between the component and the connected electronics. Reducing the number of cables reduces the cost. Figure 8 shows an embodiment of the primary component 11, which is a combination of the embodiments shown in fig. 6 and 7, the primary component 11 being provided with both a capacitor 16 and a frequency filter 17. The advantages are the same as described above.

In fig. 9 shows a primary component 11 with a base 12 provided with two different parts 122a, 122b, with respectively high and low ferrite content. "High" and "low" can be defined from a standard mixing ratio of four parts ferrite powder to one part mold casting substance. The advantages of graded ferrite content in the base 12 are described above and include, among other things, good shielding and a relatively large transmission distance.

Hereinafter, three possible methods for manufacturing (production processes) of the device according to the invention are described for coils. The chosen process of depends on the permitted cost, but also on the requirements for the application. The inventors have identified three different sets of requirements related to different applications: underwater or downhole applications where the device must withstand high pressures;

applications in harsh environments where the device must be very robust, and cost-optimized applications, where performance and production costs must be balanced.

These three applications and their implications for the method of manufacture will be discussed below. It must be emphasized that the following description and corresponding figures focus only on one side of the system (primary or secondary side).

Underwater or downhole applications

Figures 10 to 12 illustrate an embodiment of the method for manufacturing a device for underwater, downhole or other high-pressure or low-pressure applications.

In a first step, as illustrated in fig. 10, the coil 14, in this example a circular coil, is wound. The coil 14 has an outer diameter 14od and an inner diameter 14id. The coil defines a central area 14c, as shown on the left side of figure 10. The respective electrical clamps 20a are also shown in the figure. In this embodiment both on the same side of the coil, but this is not essential to the invention. Depending on the extent of windings required, the thickness 14t of the coil 14 increases. The following considerations may apply when the coil 14 is made: a. For low power applications and/or low efficiency applications, a wire with a single conductor cord is used, where its diameter is calculated based on the amount of power to be transmitted. For high-power and/or high-efficiency applications, Litz wires are used, where their diameters and number of conductor cords are calculated based on the transmission frequency and the maximum amount of power to be transmitted. A self-tying wire can be used to wind up an air coil. b. Diameter, thickness and number of turns for the coil are calculated based on the transmission distance and the amount of maximum power to be transmitted. c. The wire end of the finished coil is insulated with heat shrink or the like to achieve good insulation by molding into the ferrite-comprising substrate (the base). This also prevents mechanical stress on the wire at the starting point from the molded ferrite.

In a further step, as illustrated in fig. 11, the coil 14 and the communication channel 15 located in the center area 14c of the coil 14 are molded into a single molding layer 30. In this example, the communication channel 15 comprises a low-frequency communication channel 15-1, which is arranged on a PCB 60. Thus PCB 60 may include additional circuitry and components, or may even include an additional communication channel as shown with the high frequency communication channel 15-2. The PCB 60 is connected via a connection cable 20b. When implementing a filter on the communication channel, a common cable can be used to transmit data to both the high-frequency and low-frequency communication channels. The following considerations may apply when molding the coil 14 and the communication channel 15: a. The coil 14 and the communication channel 15 which is preferably chosen (PCB-based, coil-based and/or optical) are placed in a mold 50. It may be advantageous to have positioning marks or contours in the mold 50 to ensure accurate alignment. The mold 50 does not need to be removed from the coil 14, but can act as a protective material in the final product. However, the invention is not limited to this embodiment. b. During the molding process, a low viscosity resin and, if applicable, a hardener is poured into the mold 50 until the coil is covered or the desired insulation thickness is achieved. The correct level can be controlled by marks or contours in the mold 50 or by using an automatic dosing system. c. Vacuum can be used to remove air from the resin and between the conductor cords in the coil 14. This provides a massive device. Possible air pockets can cause conductor cords and windings to move with pressure changes. Movements of conductor cords can destroy the insulation layer of each conductor cord and cause a short circuit. Removal of air also ensures creepage distances and avoids cracking of the device due to compressive strain.

d. After pouring the resin, the resin is cured.

In a further step, as illustrated in fig. 12, a ferrite-comprising substrate 12 is applied using a molding process as well as a mechanical pressure barrier layer 70. Figure 12 further illustrates what is meant by "first side 12sl" and "second side 12s2" in the claims. The following considerations may apply when applying the ferrite-comprising substrate 12: a. Ferrite powder is mixed with a low-viscosity resin, and hardens if applicable. The ratio can be 80% ferrite powder and 20% resin, i.e. 4 parts ferrite to 1 part resin. The required ratio also depends on the desired field distribution from the coil.

b. A flexibility agent (plasticizer) can be mixed with the resin to make the cured ferrite a little softer and to make it more robust against impact. c. The ferrite mixture is poured into the mold 50 on top of the molded coil 14, 30. The correct level can be controlled by a marker or contours in the mold or by using an automatic dosing system. The thickness of the ferrite layer is calculated based on the maximum amount of power to be transmitted. d. Vacuum can be used to remove all the air from the ferrite mixture. This ensures a massive device that does not contain air.

e. After pouring the ferrite mixture, the ferrite mixture is hardened.

f. The mechanical pressure barrier layer 70 is placed on top of the mold 50 with the coil 14 and the ferrite. Aluminum or other metals are usually used as a pressure barrier, and the shape and size are adapted to fit on top of the coil and mold. The dimensions of the pressure barrier must be calculated to meet the pressure requirement for the application, so that the electronics can be placed in an atmospheric environment. Said respective cables 20a and 20b from the coil 14 and the communication channels 15 are pulled through holes in the barrier layer 70. A resin is poured into small holes in the mechanical pressure barrier layer 70 to fill the gap between the ferrite encompassing substrate 12 and the barrier layer 70, and to form a massive share.

Simulations show that objects placed in the center area 14c in the first coil 14 and the amount of ferrite in this area 14c do not have a strong influence on the coupling factor between two components. This area 14c has a low concentration of magnetic field during transmission of power, and thus less noise will be absorbed in this area 14c. This makes this area 14c ideal for the implementation of communication channels 15. There is no requirement for rotational orientation with the joining of two circularly shaped coils for wireless transmission of power. When implementing a communication channel 15 in the center area, which has no requirement for rotational orientation, the component for wireless transmission of power and communication will thus have the advantage of having no requirement for rotational orientation. The described communication channels can be implemented without requirements for rotational orientation.

The present description does not disclose in detail how the coil 14 and the communication channel 15 are to be connected within the system for wireless power transmission and communication, and which technology can be used for this. Such knowledge and technology is considered to be well known to the person skilled in the art. To position the components within the transfer area, different guiding and joining systems can be used, such as mechanical guiding and locking systems that hold the component in place when they are aligned, or magnets that will pull the components together.

In an alternative embodiment of the method, the barrier layer 70 is placed in the mold before the ferrite mixture is poured in, i.e. before the ferrite-comprising substrate 12 is made. Then the ferrite mixture will fill the gap between the molded coil 14, 30 and the mechanical pressure barrier layer 70. Likewise, vacuum can be used to remove all the air from the resin or ferrite mixture. This provided a solid device that does not contain air, which is shown in fig. 12. After pouring the ferrite mixture, the ferrite mixture is hardened.

Applications in harsh environments

The main difference between this embodiment and the embodiment from fig. 10 to 12 is that here the coil 14 is not molded before the ferrite-comprising substrate 12 is applied.

Figure 13 illustrates a similar step in the process as fig. 12. It can be observed that the mold 50 has been adapted in that it is now shaped with a thicker bottom with a recess for receiving the coil 14 as well as the PCB 60. The process now comprises two main steps instead of three, namely the manufacture (or winding ) of the coil (including the provision of the PCB) and the subsequent molding step.

1. Coil winding:

Similar considerations apply as for the underwater or downhole applications. A main difference is that in this embodiment the coil can be treated with an electrically insulating coating or other insulating material to achieve electrical isolation from the ferrite base at a later stage in the process.

2. Preparation of the ferrite-comprising substrate 12 (moulding):

The same considerations apply as for the underwater or downhole applications. The main differences are that the components on the PCB and bare metal should be electrically isolated from the ferrite. The casting mold 50 mold must have a shape that ensures correct shaping of the ferrite and that the coil is not completely immersed in the ferrite after mould-casting.

Cost-optimized applications

Similar considerations apply as for the underwater or harsh environment applications. A main difference is that there is a separate step of attaching the coil 14 and the communication channel to the ferrite by gluing, taping or using similar attachment methods. An insulating sheet can be placed between the ferrite and the coil to improve the insulation.

There are different options that can be used as communication channels: PCB-based communication channel, coil-based communication channel and optical communication channel. Some considerations for the manufacturing process are described below.

PCB-based communication channel

The communication channel is achieved by designing a PCB. The following considerations apply: For low-frequency communication channels, contact lines are formed on the PCB to form a coil with an inductance matched to the desired communication frequency. Typical frequencies are from 2 MHz to 40 MHz. One or more layers of the PCB can be used to form the coil.

For high-frequency communication channels, a circular contact line, a centered contact surface, or similar shapes having the same transmission characteristics are implemented to form a short-range capacitive antenna. Typical frequencies are from 100 MHz to 150 GHz. One or more layers on the PCB can be used to form the communication channel.

The coil, contact line and filter must be designed so that it does not absorb energy from the nearby coil, which is transmitting power.

The low-frequency and high-frequency communication channels can be connected with a filter solution consisting of discrete components. This makes it possible to connect a common coaxial cable or other type of wire pair for both the low-frequency and high-frequency signals.

The PCB is manufactured and components are assembled. Standard PCBs and laminates can be used.

A coaxial cable connects to the PCB.

The PCB can optionally be designed with only one of the communication channels. The PCB can optionally be designed with a hole in the center to allow access for combination with optical transmission channel or other objects in the center.

Coil-based communication channel

The communication channel is obtained by winding a coil similar to that already explained with reference to fig. 10 to 13. The number of turns to be made is adapted to the desired communication frequency. Typical frequencies are from 2 MHz to 40 MHz.

Optically based communication channel

1. Any type of commercially available optical transceiver (laser diode, LED diode, photosensitive diode) with lenses providing the desired transmission distance can be placed in the center of the coil to achieve optical communication. 2. Optical communication channel can be combined with both PCB and coil-based communication channel.

Claims (18)

1. Device (1) for wireless transmission of power and communication, characterized in that the device (1) comprises: a ferrite-comprising substrate (12) with a first side (12sl) and a second side (12s2) opposite the first side; a first coil (14) for wireless power transmission, wherein the first coil (14) is disposed at the first side (12sl) of the ferrite-comprising substrate (12), wherein the first coil (14) encloses a center region (14c), and a first communication channel (15, 15-1) for wireless communication, where the first communication channel (15, 15-1) is arranged in the center area (14c) inside the first coil (14), where the first coil (14) and the communication channel ( 15, 15-1) has been attached to the first side (12sl) of the substrate (12) using a mold casting process. 2. Device (1) according to claim 1, where the first coil (14) and the communication channel (15, 15-1) have been molded in a single molding layer (30) on the first side (12sl) of the substrate (12) . 3. Device (1) according to claim 1 or 2, further comprising a second communication channel (15-2) for wireless communication, where the second communication channel (15-2) is arranged in the center area (14c) inside the first the coil (14). 4. Device (1) according to claim 3, where the second communication channel is arranged in a further center area inside the first communication channel (15-1). 5. Device (1) according to any one of claims 1 to 4, wherein the device (1) comprises a through hole (25) which extends through the substrate (12). 6. Device (1) according to any one of the preceding claims, wherein the first coil (14) is at least partially buried in the ferrite-comprising substrate (12). 7. Device (1) according to any of the preceding claims, wherein the ferrite-comprising substrate (12) comprises a mixture of resin and ferrite powder. 8. Device (1) according to claim 7, where the ferrite-comprising substrate (12) comprises one part molding compound per four parts ferrite powder. 9. Device (1) according to any of the preceding claims, where the substrate (12) is provided with two or more parts (122a, 122b) with different ferrite concentrations. 10. Device (1) according to claim 9, where the ferrite concentration in the substrate (12) in a part (122b) close to the coil (14) is lower than the ferrite concentration in a part (122a) further away from the coil (14). 11. Device (1) according to any one of the preceding claims, wherein the device further comprises a capacitor (16) connected in series with the first coil (14). 12. Device (1) according to any of the preceding claims, where the communication channel (15) is connected to a frequency filter (17). 13. Method for producing the device according to any of the preceding claims, characterized in that the method comprises: arrangement of the first coil (14) and the first communication channel (15) in a mold (50); attaching the first coil (14) and the communication channel (15) to the ferrite-comprising substrate (12) using a molding process. 14. Method according to claim 13, where the ferrite-comprising substrate (12) is also formed with a mold casting process. 15. Method according to claim 14, wherein the step of fixing and the step of forming the ferrite-comprising substrate (12) are done in the same mold casting process. 16. Method according to any one of claims 13 to 15, further comprising a step of providing a mechanical pressure barrier layer (70) on the ferrite-comprising substrate (12). 17. System for wireless transmission of power and communication comprising a device (1) according to any one of claims 1 to 12. 18. System according to claim 17, wherein both the primary as well as the secondary side comprise the device (1) according to any one of claims 1 to 12.