WO2016080841A1

WO2016080841A1 - Device and method for wireless transmission of power and communication

Info

Publication number: WO2016080841A1
Application number: PCT/NO2015/050215
Authority: WO
Inventors: Geir Olav Gyland; Audun Andersen
Original assignee: Geir Olav Gyland; Audun Andersen
Priority date: 2014-11-19
Filing date: 2015-11-18
Publication date: 2016-05-26
Also published as: NO20141391A1; NO338395B1

Abstract

The invention relates to a device for wireless transmission of power and communication. The device comprises: i) a ferrite-comprising substrate (12) having a first side (12s1) and a second side (12s2) opposite to the first side; ii) a first coil (14) for wireless power transmission, wherein the first coil (14) is provided at the first side (12s1) of the ferrite-comprising substrate (12), wherein the first coil (14) encloses a centre region (14c), and iii) a first communication channel (15, 15-1) for wireless communication, wherein the first communication channel (15, 15-1) is provided in the centre region (14c) within the first coil (14). The first coil (14) and the communication channel (15, 15-1) have been fixed to the first side ( 12s1) of the substrate (12) using a moulding 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 manufacturing such device. Such device may be used for transmitting energy and communications through air, water, plastics, glass, oil and other materials, which are not electroconductive. The device may also be used for transmission through non-magnetic electroconductive materials by operating power and communication in the frequency range of 1-50 kHz. The control signal could then be sent from the secondary side to the primary side by having the secondary side modulate the amplitude of the switching signal. More specifically, the invention relates to a device for transmission of power and communication, wherein the device comprises a primary component and a secondary component provided at a distance from each other, and wherein each of the primary component and the secondary component comprises a base (or substrate), which is at least partially provided in, a ferrite-comprising material, wherein the device further comprises an energy source and a control electronic connected at least to the primary component and a feedback electronic and load connected at least to the secondary component. The electronics enables regulation of the energy transfer.

By connecting control electronics, energy source, feedback electronic and load to both the primary- and the secondary components, transmission of energy may be obtained in both directions. This may be especially useful on implementation of an inductive battery wherein both charging and discharging takes place via the same component.

Wireless, inductive transmission of energy is known technology and is used amongst other things, to operate equipment and to pass on measuring results in situations where transmission through cables or conventional connectors is inconvenient, impossible and/or dangerous. Wireless transmission of power in order to operate equipment is generally supplemented by wireless transmission of data communication for operating the equipment and returning measuring results, etc. Transmission of communication and power is commonly done by means of two separate transmission devices, which may take up a lot of space. Known technical solutions are generally not so flexi- ble with regards to the geometrical shapes of the components, which are used for the wireless transmission of power and data, and the components are furthermore commonly vulnerable to external influences in such a way that they cannot be used in situations where they are exposed to mechanical blows and/or, high pressure.

Patent publication JP 2007142081 A discloses a component for transmission of wireless power comprising a coil, a core and a screen element, wherein the core and the screen element are provided as an integral unit by moulding of a magnetic powder and a resin binder.

Patent publication JP 2006156714 concerns a method for manufacturing of a core for a component for transmission of electrical signals, where the core is moulded with mixture of a magnetic powder and synthetic resin.

In patent publication US 2008061733 Al a battery charger is described, the battery charger comprising 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.

Similarly, patent publication US 201248878 Al discloses a battery pack comprising a coil for non-contact energy transmission, wherein the coil is moulded in a structure made from a moulding substance comprising ferrite in fine particles and a resin.

Patent publication NO 320439 Bl, corresponding to US 8125208 B2, is filed by the present applicant and concerns efficient wireless transmission of energy.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

The invention is defined by the independent patent claims. The dependent claims define 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 to the first side;

a first coil for wireless power transmission, wherein the first coil is provided at the first side of the ferrite-comprising substrate, wherein the first coil encloses a centre region, and a first communication channel for wireless communication, wherein the first communication channel is provided in the centre region within the first coil, wherein the first coil and the communication channel have been fixed to the first side of the substrate using a moulding process.

The effects of the combination of the features of the invention are as follows. By providing the first communication channel within the centre region of the first coil and by subsequently moulding said assembly into a single moulding layer a very compact and very robust device is obtained. Simulations show that objects placed in the centre region of the first coil and the amount of ferrite in this region does not heavily infl uence the coupling factor between two components. This region has a low concentration of magnetic field during transmission of power and thus less noise will absorbed in this region. This makes this region ideal for implementing communication channels. By choosing for a moulding process for manufacturing said device, it is rendered possible to start with the coil and effectively build said device in subsequent layers. After moulding the first coil and the first communication channel the ferrite-comprising substrate may be conveniently provided a backside of the single moulding layer comprising the coil and the communication channel. It must be stressed that the first coil and the first communication channel need not be oriented in a flat orientation. The coil may be shaped to follow a cylindrical, cone or dome-structure as well, for example. Whatever shape is chosen it is only important to choose a casting mould with a shape, which matches the shape of the coil and the communication channel. It must be stressed that the claims are directed to only one of the primary and secondary components in a communication/transmission system. It must be understood that the invention may be applied on both sides or on only one of said sides of said communication/transmission systems. This means that the invention may be used on the primary side, the secondary side, or both.

In an embodiment of the device in accordance with the invention the first coil and the communication channel have been moulded in a single moulding 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, wherein the second communication channel is provided in the centre region within the first coil. In case a further communication channel is to be implemented, such communication channel may be conveniently placed within the same centre region as the first communication channel. In an embodiment of the device in accordance with the invention the second communication channel is provided in a further centre region within the first communication channel. In case the first communication channel is shaped as a coil for example that is oriented concentric with regards to the first coil, the second communication channel may be provided within a further centre region defined by the first communication channel.

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

In an embodiment of the device in accordance with 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 the device in accordance with the invention the ferrite- comprising substrate comprises a mixture of resin and ferrite powder. By using a relatively thin moulding substance a homogenous mixture with high ferrite contents may be obtained. The mixing ratio may be approximately one part moulding substance to four parts ferrite powder. Such a composition will provide good transmission properties and the desired homogeneity. Moulding with ferrite powder is a production friendly process, which does not require expensive tools or casting moulds with high precisions, at the same time as the process allows for moulding of complex shapes like plane-, cylindrical- or cone-shaped-bases (or substrates). Shaping the coil and the 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 a one part moulding paste per four parts of ferrite powder.

In an embodiment of the device in accordance with the invention the substrate is provided with two or more portions with different ferrite concentrations. By adjusting the mixing ratio of ferrite and moulding substance, and thus grading the ferrite concentra- tion of the base, the magnetic field may be focused.

In an embodiment of the device in accordance with the invention the ferrite concentration in the substrate in a portion near the coil is lower than the ferrite concentration in a portion further away from the coil. In this embodiment the transmission distance may be increased at the same time as the highly concentrated ferrite material works as a screen for the magnetic field. A skilled person will know that a lower concentration of ferrite will result in the flux lines being emitted out in a broader manner, which allows for larger transmission distances over an air gap between the primary- and secondary components.

If the coil for power transmission is at least partially moulded in the ferrite material, this could give an increased connection between the coil and the base and result in an increased induction of the coil such that the coil may be provided with a lower number of windings and thus may be manufactured 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 current and/or communication may also be completely or partially moulded into the base, which will provide a robust connection to the coil and the communication channel. In one embodiment the portion of the coil and of the communication channel, which is not surrounded by the ferrite material, may be moulded in a resin. This will provide a very good protection against blows and short-circuiting, and it will render the device more resistant to pressure. Thus, the device may for instance be used under water, for example at a seabed in connection with exploration and recovery 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 an embodiment of the device in accordance with the invention the communication channel is connected to a frequency filter. The frequency filter will make possible the use of only one pair of cables for the transmission of communication and power. The filter, which may be of a kind known per se, may have a corner frequency in the range between the switching frequency for transmission of power and the one or more frequencies, which are used for transmission of communication, such that only communication signals may be transmitted to and from the communication channel. As an a lternative or in addition, a band-stop filter may be integrated in the control electronic for filtering out interference in the frequency ranges, which the communication cha nnel uses for transmission. Both high and low frequency communication channels can be implemented on a printed circuit board. The low frequency communication channel may be provided as windings implemented as traces on a printed circuit board. The inductance of the windings may be adapted to a desired communication frequency. The traces will be able to function as an inductive coupling where the inductance is adapted to the desired communication frequency for different communication components, which one wants to connect, as will be known to the skilled person. The inductance may be adapted by means of separate components or by forming of the traces on the printer circuit board.

The high frequency communication channel may be provided as a trace or pad implemented on a printed circuit cardboard. The traces or pads will be able to function as a capacitive coupling where the impedance is adapted to the desired communication frequency for different communication components, which one wants to connect, as will be known to the skilled person. The impedance may be adapted by means of separate components or by forming of the lines on the printer circuit board .

Thus, the transmission of communication may be either of a low-frequency type or of a high-frequency type or both.

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

In a second aspect the invention relates to a method for manufacturing the device according to any one of the preceding claims. The method comprises:

providing the first coil and the first communication channel in a casting mould; fixing the first coil and the communication channel to the ferrite-comprising substrate in using a moulding process. The advantageous and effects of the method of manufacturing the device of the invention are tightly connected with those of the device itself. Yet some further advantages will be mentioned with regards to the embodiments.

In an embodiment of the method in accordance with the invention the ferrite- comprising substrate is also formed with a moulding process. A moulding process is a very flexible way of forming the ferrite-comprising substrate. Ferrite powder is conveniently mixed with resin before it is cast into the casting mould. More details about the method and its embodiments will be given in the detailed description of the figures.

In an embodiment of the method in accordance with the invention the step of fixing and the step of forming the ferrite-comprising substrate is done in the same moulding process. This embodiment is very advantageous, because a casting mould of the moulding process can be effectively reused in the process, i.e. the method of this embodiment has less method steps and will therefore be cheaper.

In an alternative embodiment of the method in accordance with the invention the ferrite-comprising substrate is attached (glued, taped or fastened with other similar methods) to the first coil and the first communication channel. The advantage of this embodiment is that it renders 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 ensure the required specifications that are 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 is said "primary side", this may be exchanged with "secondary side" and vice versa. Quite often in bidirectional communication and/or transmission it is quite arbitrary to define which side is primary and which side is secondary.

In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein :

Fig. 1 shows, seen from above, a primary component of a device in accordance with the present invention;

Fig. 2 shows in perspective, the primary component in Fig. 1 ;

Fig. 3 shows, seen from the side, a device in accordance with the present invention;

Fig. 4 shows, seen from the side, cross-sections of two components in accordance with the present invention;

Fig. 5 shows, seen from the side, differently shaped bases, which are used in a device in accordance with the present invention; Fig. 6 shows, seen from the side, an embodiment of a primary component of a device in accordance with 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 of a device in accordance with the present invention; and

Fig. 9 shows, seen from the side, an embodiment of a primary component in accordance with the present invention.

Fig. 10 illustrates with a top view and a cross section view from the side, a stage of the method of manufacturing the device of the invention;

Fig. 11 illustrates with a top view and a cross section view from the side, a further stage of the method of manufacturing the device of the invention;

Fig. 12 illustrates with a top view and a cross section view from the side, yet a further stage of the method of manufacturing the device of the invention, and

Fig. 13 illustrates a cross section view from the side of another embodiment of the method of manufacturing in accordance with the invention.

It should be noted that the above-mentioned embodiments and the ones 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 parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a cla im. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Hereinafter, the reference numeral 1 denotes a device for transmission of power and communication in accordance with the present invention, as indicated in the Figs. 3 and 4. The figures are shown schematically and simplified, and the same reference numeral refers 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 are for sake of simplicity of the drawings not shown. The device

I for transmission of 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.

Fig. 1 shows a primary component 11 comprising a base 12 (this element is also being referred to as substrate in this description), wherein a coil 14 for inductive transmission of wireless power is arranged. The base 12 is in the shown embodiment provided with a circular cross-section with a hole 25 in the middle. The coil 14, which is provided concentrically around the hole of the base 12, could be partially moulded into the base 12 as described in the general part of this application. The primary component

I I further comprises a channel 15 for 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 of the base 12. The base 12 is at least partially provided in a ferrite-comprising material 121.

Fig. 2 shows the same primary component 11 seen in perspective, wherein it can be seen that the base 12 is shaped as a short cylinder.

Fig. 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 on the primary component 11 and the secondary component 13.

Fig. 4 shows a cross-section from the side of device 11 and device 13 in accordance with the present invention. On the left side of the Fig. is shown a cable 20a connecting the coil 14 on the primary component 11 with a control electronic and an energy source (not shown), which may be a frequency-controllable power supply, while the coil 14 on the secondary component 13 may be connected to a feedback electronic and load (not shown) . It is referred to the above-mentioned patent publication NO 320439 Bl, corresponding to US 8125208 B2, for a more detailed description of the technology. To the right in the figure, is shown a cable 20b, which for instance connects the communication channel 15 to a not shown communication electronic. The figure illustrates also the hole 25 as discussed with reference to Fig. 1.

Fig. 5 shows bases 12 provided with alternative geometries. Moulding with ferrite powder and mixed with a resin, as for instance epoxy or polyurethane, gives great flexibility and thus allows shaping of bases of almost any geometry. Shown in the figure are bases of conical- and cylinder-shapes.

In Fig. 6 is shown 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 may be found in said patent publication NO 320439 Bl, 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 a capacitor 16 connected in series with an inductor 14 will form a voltage resonance circuit, the shown embodiment will allow the potentially high voltage part of the system to be moved away from the not shown control electronics, and thereby make it easier to fulfil the safety requirements and it reduces the voltage isolation requirements on the cable and connectors.

Fig. 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 may be of a type known per se, has a corner frequency in the range between the switching frequency for transmission of power and the one or more frequencies which are used for transmission of communication, such that only communication signals are transmitted to and fro the communication channel 15. This allows for the use of a common cable for transmission of communication and power between the component and connected electronics. Reducing the number of cables reduces the cost.

Fig. 8 shows an embodiment of the primary component 11, which is a combination of the embodiments shown in the Figs. 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 a primary component 11 is shown with a base 12 provided with two different portions 122a, 122b, with high and low ferrite content, respectively. "High" and "low" may be defined from a standard mixing ratio of four parts ferrite powder to one part moulding substance. The advantages of graded ferrite content in the base 12 are described above and include amongst other things good screening and relatively large transmission distance.

Hereinafter, three potential methods of manufacturing (production processes) the device of the invention are described for coils are described. The process chosen depends on allowable cost, but also on the application requirements. The inventors have identified three different requirement sets relating to different applications:

subsea or down-hole applications where the device must stand high pressures; harsh environment applications 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 manufacturing will be discussed hereinafter. It must be stressed that the description hereinafter and the corresponding figures focus on only one side of the system (primary or secondary side).

Subsea or down-hole applications

Figs. 10 to 12 illustrate an embodiment of a method of manufacturing a device for subsea, down-hole or other high or low-pressure applications.

In a first step, as illustrated by Fig. 10, the coil 14 is wound, in this example a circular coil. The coil 14 has an outer diameter 14od and an inner diameter 14id. The coil defines a centre region 14c as shown on the left side of Fig. 10. The respective electrical terminals 20a are also shown in the figure. In this embodiment both on the same side of the coil, but that is not essential to the invention. Depending on the amount of windings that are needed the thickness 14t of the coil 14 increases. The following considerations may apply when making the coil 14:

a. For low-power and/or low-efficiency applications a single strand wire is being used with its diameter calculated based on the amount of power to be transferred . For high-power and/or high-efficiency applications, Litz wires are being used with its diameters and number of strands being calculated based on the transmission frequency and the maximum amount of power to be transferred. A self-bonding wire may be used to wind up an air coil.

b. Diameter, thickness and number of turns of the coil is calculated based on transmission distance and amount of maximum power to be transferred .

c. The wire end on the finished coil is isolated with heat shrink or similar to obtain good isolation when moulded into the ferrite-comprising substrate (base). This also prevents mechanical stress on the wire at the exit point of the moulded ferrite.

In a further step, as illustrated by Fig. 11, the coil 14 and the communication channel 15 that is placed in the centre region 14c of the coil 14 are moulded into a single moulding layer 30. In this example, the communication channel 15 comprises a low frequency communication channel 15-1, which is provided on a PCB 60. Such PCB 60 may comprise further circuitry and components, or may even comprise a further communication channel as indicated by the high frequency communication channel 15- 2. The PCB 60 is connected via a connection cable 20b. By implementing a filter on the communication channel a common cable can be used to transfer data to both the high and low frequency communication channels. The following considerations may apply when moulding the coil 14 and the communication channel 15:

a. The coil 14 and the communication channel 15 of choice (PCB based, coil based and/or optical) are placed in a casting mould 50. It may be beneficial to have positioning marks or contours in the casting mould 50 to ensure precise alignment. The casting mould 50 does not have to be removed from the coil 14, but could act as a protecting material in the final product. However, the invention is not limited to this embodiment.

b. During the moulding process a resin with low viscosity and a hardener, if applicable, is being poured into the casting mould 50 until the coil is covered or desired isolation thickness is achieved. The proper level could be controlled by a marks or contours in the casting mould 50 or by using an automatic dosing system.

c. Vacuum may be used to remove air from the resin and between the strands in the coil 14. This ensures a solid device. Potential air pockets could cause strands and windings to move with pressure changes. Movements of strands can destroy the insulation layer on each strands and cause shortening. Removing air also ensures creep- age distances and avoids cracking of the device due to pressure strain.

d. After pouring in the resin, the resin is hardened .

In a further step, as illustrated by Fig. 12, a ferrite-comprising substrate 12 is applied using a moulding process as well as a mechanical pressure barrier layer 70. Fig. 12 further illustrates what is meant with "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 hardener if applicable. The ratio may be 80% ferrite powder and 20% resin, i.e. 4 parts ferrite on 1 part resin. The required ratio also depends on the desired field distribution from the coil.

b. A flexibilizer (plasticizer) might be mixed in with the resin to make the hardened ferrite a bit softer and to be more robust to impact.

c. The ferrite mix is poured into the casting mould 50 on top of the moulded coil 14, 30. The proper level could be controlled by a marks or contours in the casting mould or by using an automatic dosing system. The thickness of the ferrite layer is calculated based on the maximum amount of power to be transferred.

d. Vacuum may be used to remove all the air from the ferrite mix. This ensures a solid device not containing any air.

e. After pouring in the ferrite mix, the ferrite mix is hardened.

f. The mechanical pressure barrier layer 70 is being placed on top of the casting mould 50 with the coil 14 and the ferrite. Aluminium or other metals are commonly used as a pressure barrier and the shape and size are adapted to fit on top of the coil and the casting mould. The dimensions of the pressure barrier must be calculated to meet the pressure requirement of the application such that the electronic can be placed in an atmospheric environment. Said respective cables 20a and 20b from the coil 14 and the communication channels 15 are being 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-comprising substrate 12 and the barrier layer 70 and to make a solid part.

Simulations show that objects placed in the centre region 14c of the first coil 14 and the amount of ferrite in this region 14c does not heavily influence the coupling factor between two components. This region 14c has a low concentration of magnetic field during transmission of power and thus less noise will absorbed in this region 14c. This makes this region 14c ideal for implementing communication channels 15. There is no rotational orientation requirements when mating two circular shaped coils for wireless transmission of power. Thus by implementing a communication channel 15 in the centre region, which do not have rotational orientation requirements the component for wireless transmission of power and communication will have the benefit of having no rotational orientation requirements. The communication channels described can be implemented without rotational orientation requirements.

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

In an alternative embodiment of the method, the barrier layer 70 is placed in the casting mould before the ferrite mix is poured in, i.e. before the ferrite-comprising substrate 12 is made. Then the ferrite mix will fill the gap between the moulded coil 14, 30 and the mechanical pressure barrier layer 70. Likewise, vacuum may be being used to remove all the air from the resin or ferrite mix. This ensures a solid device not containing any air, which is shown in Fig 12. After pouring in the ferrite mix, the ferrite mix is hardened. Harsh environment applications

The main difference between this embodiment and the embodiment from Figs. 10 to 12 is that here the coil 14 is not moulded before the ferrite-comprising substrate 12 is applied. Fig. 13 illustrates a similar stage of the process as Fig. 12. It can be observed that the casting mould 50 has been adapted in that it now is shaped with a thicker bottom having a recess for receiving the coil 14 as well as the PCB 60. The method now comprise two main steps instead of three, namely the manufacture (or winding) of the coil (including the provision of the PCB) and the subsequent moulding step.

1. Winding of coil :

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

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

The same considerations apply as for the subsea or down-hole applications. The main differences are that the components on the PCB and exposed metal should be electrically isolated from the ferrite. The casting mould 50 mould must have a shape that ensures that proper shaping of the ferrite and that the coil is not fully immersed into the ferrite after moulding.

Cost-optimized applications

Similar considerations apply as for the subsea or harsh-environment applications. A main difference is that there is a separate step of fastening the coil 14 and the communication channel to the ferrite by gluing, taping or using similar fastening methods. An isolation sheet could be placed between the ferrite and the coil to improve isolation.

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

PCB based communication channel

The communication channel is obtained by designing a PCB. The following considerations apply:

For low frequency communication channels traces are made up on the PCB to form a coil with an inductance that is adapted to the desired communication frequency. Typical frequencies are from 2MHz to 40MHz. One or several layers on the PCB could be used to form the coil.

For high frequency communication channels a circular trace, a centred pad or similar shapes that has the same transmission properties is implemented to form a short-range capacitive antenna. Typical frequencies are from 100MHz to 150GHz. One or several layers on the PCB could be used to form the communication channel.

The coil, trace and filter must be designed such that it does not absorb energy from the nearby coil, which transfers power.

The low and high frequency communication channels can be connected by a filter solution made up of discrete components. This makes it possible to connect one common coax cable or another type of wire pair for both the low frequency and the high frequency signals.

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

A coax cable is connected to the PCB.

Optionally, the PCB can be designed with just one of the communication channels.

Optionally, the PCB can be designed with a hole in the centre to allow combination with optical transmission channel or other objects in the centre.

Coil based communication channel

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

Optical based communication channel

1. Any type of commercial available optical transceiver (laser diode, LED diode, light-sensitive diode) with lenses that ensures desired transmission distance can be put in the centre of the coil to obtain optical communication.

2. Optical communication channel can be combined with both PCB and coil based communication channel .

Claims

C l a i m s

1. Device (1) for wireless transmission of power and communication,

c h a r a c t e r i s e d i n that the device (1) comprises:

a ferrite-comprising substrate (12) having a first side (12sl) and a second side (12s2) opposite to the first side;

a first coil (14) for wireless power transmission, wherein the first coil (14) is provided at the first side (12sl) of the ferrite-comprising substrate (12), wherein the first coil (14) encloses a centre region (14c), and

a first communication channel ( 15, 15-1) for wireless communication, wherein the first communication channel ( 15, 15-1) is provided in the centre region (14c) within the first coil (14),

wherein the first coil (14) and the communication channel ( 15, 15-1) have been fixed to the first side (12sl) of the substrate (12) using a moulding process.

2. Device (1) according to claim 1, wherein the first coil ( 14) and the communication channel (15, 15-1) have been moulded in a single moulding 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, wherein the second communication channel (15-2) is provided in the centre region (14c) within the first coil (14).

4. Device (1) according to claim 3, wherein the second communication channel is provided in a further centre region within 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) extending 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 one 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, wherein the ferrite-comprising substrate (12) comprises a one part moulding paste per four parts of ferrite powder.

9. Device (1) according to any one of the preceding claims, wherein the substrate (12) is provided with two or more portions (122a, 122b) with different ferrite concentrations.

10. Device (1) according to claim 9, wherein the ferrite concentration in the substrate (12) in a portion (122b) near the coil (14) is lower than the ferrite concentration in a portion (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 one of the preceding claims, wherein the communication channel (15) is connected to a frequency filter (17).

13. Method for manufacturing the device according to any one of the preceding claims, c h a r a c t e r i s e d i n that the method comprises: providing the first coil (14) and the first communication channel ( 15) in a casting mould (50);

fixing the first coil ( 14) and the communication channel ( 15) to the ferrite-comprising substrate (12) in using a moulding process.

14. Method according to claim 13, wherein the ferrite-comprising substrate ( 12) i also formed with a moulding process.

15. Method according to claim 14, wherein the step of fixing and the step of form ing the ferrite-comprising substrate (12) is done in the same moulding process.

16. Method according to any one of claim 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.