WO2009050625A2

WO2009050625A2 - Power transfer system

Info

Publication number: WO2009050625A2
Application number: PCT/IB2008/054174
Authority: WO
Inventors: Remco H. W. Pijnenburg; Bruno Motte
Original assignee: Nxp B.V.
Priority date: 2007-10-15
Filing date: 2008-10-10
Publication date: 2009-04-23
Also published as: WO2009050625A3

Abstract

The present invention refers to a power transfer system which comprises a power transfer device (10) as well as at least one portable device (20). The power transfer device (10) includes at least one coil arrangement (CA) for generating or receiving a magnetic field, and a first controller (15) coupled to the coil arrangement (CA) for driving the coil arrangement (CA) to supply power to the portable device (20) placed upon the power transfer device (10), via the generated magnetic field. The portable device (20) includes a further coil (23) for generating and receiving a magnetic field, a battery power source (21), and a second controller (22) coupled to the further coil (23) for supplying power received via the magnetic field generated by the power transfer device (10), to charge the battery power source (21). Specifically, the first controller (15) and the second controller (22) are adapted to respectively drive the coil arrangement (CA) of the power transfer device (10) and the further coil (23) of the portable device (20) to establish between the power transfer device (10) and the portable device (20) a near field communication link (NFC link) (32) for transferring data, and a power transfer link (31) for supplying power for charging the battery power source (21) of the portable device (20).

Description

POWER TRANSFER SYSTEM

FIELD OF THE INVENTION

The present invention relates to a power transfer system for transferring electric power from a power supply device to a portable device.

BACKGROUND OF THE INVENTION

Portable devices, and in particular electronic equipment, such as mobile phones or small hand-held computers and wireless devices include secondary power cells for power supply which are usually provided in the form of rechargeable power cells (rechargeable batteries) saving the user the costs and the inconvenience of regularly having to purchase new (not rechargeable) cells. Rechargeable cells are preferred due to economical and environmental reasons.

A charging operation of the rechargeable cells can be performed by using an adaptor or charger which takes power from a public electrical power network (mains power supply) or other adequate sources of power. The adaptor or charger connected to the mains power supply is further connected by a supply line and a suitable connector to the portable device, and charging starts immediately upon connecting these devices. When the charging operation is completed, this is usually displayed on the display means of the portable device, and charging may be stopped or reduced.

Conventional adaptors or chargers exhibit a number of problems when used for recharging secondary cells of any arbitrary portable device.

The adaptors and chargers usually require the users to plug a connector into the device, and the devices cannot be used in wet environment due to the possibility of corroding or shorting out the contacts, and also such devices cannot be used in flammable gaseous environment due to the possibility of creating electrical sparks. The problems above can be solved by replacing the conventional chargers or adaptors by inductive chargers for transmitting the electric energy for charging the batteries of a device by means of a magnetic field and a direct magnetic coupling without a physical electrical connection. Since the inductive chargers for wireless charging remove the need to have open electrical contacts in conjunction with a cable connection it is possible to use such chargers in wet or dusty environments since both the chargers and the device to be charged can be provided as sealed devices. The basical principal of such inductive chargers involves magnetic cores with a coil wound around the cores, and a generated magnetic field penetrating through the air gap or a region of non-magnetic material between the devices and forming a magnetic inductive link for power transmission.

The arrangements as mentioned above, however, lead to a non-uniform flux distribution of the magnetic field so that the charging effectivity is largely dependent from the correct placement of the portable device on the inductive charger.

According to further developments there is provided a planar inductive battery charger, an example of which is disclosed in prior art document WO 03/105308 Al. On a charging surface of a planar charging module is at least one planar coil or a plurality of planar coils arranged to generate a planar magnetic field. By means of this planar magnetic field an inductive coupling to a device placed thereon is established when this device (a portable device such as a mobile phone) is also equipped with a corresponding magnetic coil. The battery included in the portable device can be charged when the portable device is placed on the planar surface of the charging module and the magnetic field of the charging module is coupled to the coil of the portable device. That is, when the portable device is placed on the charging module which constitutes a docking station with integrated inductive link for power transfer, this also poses several other problems. For almost every portable device there is the need of having a different docking station, since the shape of the devices may vary considerably from device to device and manufacturer to manufacturer, and the users need to have several different docking stations for different devices in use. Moreover, every docking station or every charging module needs to be plugged into sockets of a mains power supply, and when several docking stations are used together, they take up space in plug strips and create a messy and confusing tangle of wires. To overcome such limitations of inductive power transfer systems, which require that secondary devices need to be placed on predefined positions on the charging module thereof, power transfer pads have been developed, these pads generating an electromagnetic field over a large area, and preferably the whole pad area. The user can simply place one or more devices the batteries of which are to be charged on the pad with no requirement to place them accurately or at a predetermined position.

In the above-described planar charging module of document WO 03/105308 Al an array of planar coils is provided and only coils which are needed are activated. The electromagnetic field generated is perpendicular to the pad and only around the position where the portable device is placed. The relative location of the portable device on the planar charging module can be sent and a control unit can then activate the appropriate coils to deliver power to these coils which in turn deliver power via the magnetic field to the portable device. In view of a charging efficiency when the portable device is placed on the charging module or docking station for enabling a wireless charging of the portable device the user must provide a setting of the charging module or docking station to obtain an optimized charging process with the highest effectivity and the minimum time duration for successfully completing the charging process. This is, however, cumbersome for the user as the different portable devices the batteries or rechargeable cells of which have to be charged again by means of the charging module or docking station need different settings depending on the kind of portable device in use. It is therefore likely that a less effective charging process is started which takes a longer time than necessary, and an overcharging of the battery or the rechargeable cells and a deterioration thereof can hardly be avoided.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention, to provide a power transfer system and a method of controlling a power transfer system which ensure a correct charging operation depending upon the kind of portable device to be charged. According to the present invention, the object is accomplished by a power transfer system and a method of controlling the power transfer system as put forward in the appended claims.

The power transfer system of the present invention comprises a power transfer device as well as at least one portable device. The power transfer device includes at least one coil arrangement for generating or receiving a magnetic field, and a first controller coupled to the coil arrangement for driving the coil arrangement to supply power to the portable device placed upon the power transfer device, via the generated magnetic field. The portable device includes a further coil for generating and receiving a magnetic field, a battery power source, and a second controller coupled to the further coil for supplying power received via the magnetic field generated by the power transfer device, to charge the battery power source.

Specifically, the first controller and the second controller are adapted to respectively drive the coil arrangement of the power transfer device and the further coil of the portable device to establish between the power transfer device and the portable device a near field communication link (NFC link) for transferring data, and a power transfer link for supplying power for charging the battery power source of the portable device.

Hence, according to the present invention, the power transfer system consists of the power transfer device which can generate a magnetic field to transmit power via this magnetic field, and corresponding coils arranged in the power transfer device and in the portable device, as well as of this portable device which is designed so that an inductive link between the power transfer device and the portable device can be established. To this end, each of the power transfer device and the portable device comprises a controller (respective first and second controller), and the first controller of the power transfer device is connected to a coil arrangement and drives this coil arrangement for generating or receiving a magnetic field. Similarly, the second controller arranged in the portable device is connected to a further coil arranged in the portable device, and drives this coil for generating or receiving a magnetic field.

Moreover, each of the first and second controllers can drive the respective coil for establishing a data communication link in the form of a near field communication (NFC) as well as for establishing a power transfer link for transferring electric power via the magnetic field generated in the power transfer device to the portable device placed on the power transfer device for charging the rechargeable cells or the battery power source in the portable device. In both cases, i.e. for either establishing a data communication link via near field communication (NFC) or a power transfer link the second controller drives the coil arranged in the portable device, and in a similar manner the first controller drives the coil arrangement in the power transfer device, so that the coil arrangement and the coil, respectively, are used for both the data communication link via near field communication (NFC) and the power transfer link. The data communication link on the basis of the near field communication

(NFC) establishes a link for versatile data communication, the link being automatically established when the portable device comes into the near field communication range of the power transfer device. When the data communication link based on the near field communication is established, data peculiar to the properties of the portable device can be transmitted to the power transfer device so that an automatic setting of the power transfer device depending upon the kind of portable device used can be performed.

According to the method of controlling a power transfer system which includes a power transfer device and at least one portable device, the method includes a step of driving the coil arrangement by the first controller and the further coil by the second controller to establish a data communication link based on a near field communication, exchanging data between the power transfer device and the portable device by the near field communication, and driving the coil arrangement by the first controller and the further coil by the second controller to establish a power transfer link for supplying power to the portable device for charging the battery power source.

That is, when any portable device which is equipped for performance of near field communication (NFC) and having the battery power source thereof requiring recharging, is placed on the power transfer device, the portable device and the power transfer device are arranged close to each other which is in the near field communication range, so that automatically on the basis of the near field communication a data communication link is established and a data exchange can be performed. Specifically, data peculiar to the portable device and reflecting the technical properties thereof can be transmitted to the power transfer device by means of the near field communication (NFC) so that depending upon the detected kind of portable device the charging operation can be set in the power transfer device to ensure an optimized and gentle charging of the battery power source (rechargeable cells) of the portable device.

In this connection, the various portable devices of different kind and charging requirements owned by the user and having a near field communication (NFC) functionality can be easily charged without the requirement of a manual setting of the power transfer device to obtain an optimized charging process. By means of the automatic establishment of a data communication link by means of near field communication manual operations and supervision by the user are reduced to a minimum while a maximum of operability can be obtained.

The data exchange between said portable device and said power transfer device includes data peculiar to the portable device, and may include identification data of said portable device.

The first controller of the power transfer device includes a driver circuit for driving the first and second coils to first establish the data communication link and then establish said power transfer link, and the second controller of the portable device includes a driver circuit for driving said further coil to first establish said data communication link and then establish said power transfer link. Upon establishment of said data communication link said second controller of said portable device are adapted to transmit identification data to said power transfer device for a data matching, and upon verification of said identification said first controller being adapted for starting wireless power transfer to the portable device.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows the basic concept of the present invention in the form of a schematic diagram.

Fig. 2 shows an embodiment of the present invention with more details of the power transfer device and the portable device shown in Fig. 1.

Fig. 3 shows a circuit arrangement for driving magnetic coils arranged in the power transfer device as well as the portable device as shown in Fig. 2.

Fig. 4 shows a flow chart of a data communication process carried out for establishing a data communication link. Fig. 5 shows the basic arrangement of the power transfer system according to a second embodiment of the present invention.

Fig. 6 shows a third embodiment of the power transfer system according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

A first embodiment of the power transfer system according to the present invention is now described in detail in conjunction with Fig. 1 to 3.

Fig. 1 shows the basic arrangement of the present invention in the form of a schematic diagram in which a power transfer device 10 is provided as a charging device or a charging pad for a portable device 20 which includes a battery power source 21 in the form of a rechargeable battery which is to be charged by the power transfer device 10. That is, the portable device 20 is powered by the battery power source 21.

The power transfer device 10 receives power from a mains power supply network PS which is usually provided in the form of a public power supply network. In case the power transfer device 10 is connected to the mains power supply PS, the power transfer device 10 is able to deliver electric power to the portable device 20 or charging the battery power source 21 of the portable device 20.

In general, the portable device 20 must be placed on the power transfer device 10 or must be located very close to the power transfer device 10. This is the precondition for obtaining a magnetic coupling (inductive coupling) between the power transfer device 10 and the portable device 20.

As is shown in Fig. 1, a communication data link 32 on the basis of a near field communication (NFC) is established between the power transfer device 10 and the portable device 20.

In addition to the basic structure of the power transfer system according to the present invention as is shown in Fig. 1 further details of the structure of each of the power transfer device 10 and the portable device 20 are shown in Fig. 2 which is based on the structure shown in Fig. 1. Moreover, the power transfer device 10 and the portable device 20 have a magnetic coupling for establishing a power transfer link 31 for supplying power to the portable device 20 for charging the battery power source 21, as well as a data communication link 32 based on the near field communication (NFC).

The power transfer device 10 is basically a planar power transfer device 10 having a coil arrangement CA as shown in Fig. 2. A first power transfer coil 11, a second power transfer coil 12 as well as a data communication coil 13 constitute the coil arrangement CA of the power transfer device 10.

The different coils of the coil arrangement CA are connected to a first controller 15 arranged in the power transfer device 10 for driving the coil arrangement CA to establish and obtain the power transfer link 31 as well as the communication link 32 based on near field communication, that is, the coils involved are adapted for generating or receiving a magnetic field.

In a similar manner the portable device 20 comprises a second controller 22 which receives power from the battery power source 21 and is further connected to a coil 23 which serves for establishing a power transfer link for receiving power from the power transfer device 10 and for establishing the data communication link 32 based on near field communication (NFC). That is, the second controller 22 of the portable device 20 drives the coil 23 to establish either the power transfer link 31 or the data communication link 32 between the portable device 20 and the power transfer device 10, that is, the coil 23 is adapted for generating or receiving a magnetic field.

For establishing the power transfer link 31 and the communication link 32 as is shown in Fig. 1 and 2 between the power transfer device 10 and the portable device 20, the portable device 20 must be arranged closely to the power transfer device 10 so that a magnetic field generated by the coil arrangement CA of the power transfer device 10 can penetrate the coil 23 of the portable device 20, and a magnetic field generated by the coil 23 of the portable device can penetrate the coil arrangement CA of the power transfer device 10 to obtain the necessary magnetic or inductive coupling.

Fig. 2 shows the first and second power transfer coils 11 and 12 of the power transfer device 10, but the power transfer device 10 is not limited to this coil arrangement shown in Fig. 2 which only constitutes an explanatory example, and further power transfer coils can be arranged on the power transfer device 10 if needed or appropriate. When further power transfer coils are provided in addition to the power transfer coils 11 and 12 in the power transfer device 10 shown in Fig. 2, plural portable devices 10 can be placed on or close to the power transfer device 10 provided that the magnetic coupling between the coil arrangement CA of the power transfer device 10 and the coil 23 of the respective portable device 20 is assured.

Hence, both the power transfer device 10 and the portable device 20 include a coil arrangement or a coil, respectively, to establish between the power transfer device 10 and the portable device 20 a communication link 32 on the basis of a near field communication for exchanging data, and the power transfer link 31 for supplying power from the power transfer device 10 to the portable device 20 for charging the battery power source 21 of the portable device 20.

Regarding the technology of near field communication (NFC) forming the basis for the communication link 32 between the power transfer device 10 and the portable device 20, both devices need to have the near field communication functionality (NFC functionality) so that a communication link on the basis of the near field communication can be initiated and established.

Specifically, the near field communication NFC is a very short-range wireless technology, for distances measured in centimeters, and is optimized for intuitive, easy and secure communication between various devices, such as the above power transfer device 10 and the portable device 20, without any configuration to be carried out by the user. To obtain the data communication link between two devices in question, it is necessary for the user to bring these devices close together or even to make them touch. The NFC interfaces or circuits arranged in the particular devices will automatically connect and configure themselves to form a peer-to-peer network.

Devices to communicate via a data communication link 32 on the basis of the near field communication (NFC) must therefore be equipped with the circuits and magnetic coils for establishing the data communication link 32, and such NFC circuits and coils can be included, for example, in wireless mobile communication devices like mobile phones, PDAs and the like. Confidential data and data with presenting value can be stored in a secure memory area and can always stay in the portable device (mobile device). The NFC functionality included in the portable device, for example in a PDA or a mobile phone can be transmitted as the data transmission or data communication and can be encrypted by a secure NFC functionality using a private encryption key stored on the mobile phone. Furthermore, in case an NFC functionality is implemented into a portable device such as any wireless mobile communication device like a mobile phone, further application can be provided, such as for example a virtual stored transport ticket or an access key to any building. The technology of near field communication (NFC) involves a frequency standard of 13.56 MHz frequency and which is in general used for any radio frequency identification (RFID). The standard of near field communication (NFC) is referenced in prior art document WO 2006/085246 Al.

Referring back to the present invention as shown in Fig. 2, the portable device 20 includes the coil 23 which serves for both establishing a data communication link 32 based on near field communication, as well as for establishing the power transfer link 31 which serves for transmitting power in a wireless manner from the power transfer device 10 to the portable device 20. Both links 31 and 32 require magnetic coupling which is provided by respective magnetic coils in both devices for which an interconnection is to be provided, and the magnetic coupling requires an arrangement of both devices close to each other, and preferably that the portable device 20 is placed on a planar surface or adequate surface on the power transfer device 10. The short distance of the data communication link 32 based on near field communication lies between 0 and 0.1 m.

Fig. 3 shows the basic structure of a circuit arrangement which can be provided in the portable device 20 and specifically in the controller 25 thereof for driving the coil 23 which is a single coil and which serves for both establishing or supporting the data communication link 32 as well as the power transfer link 31 between the portable device 20 and the power transfer device 10 when both devices are located within the very small distance of the power supply range which is smaller than the transmission range for near field communication.

It is therefore necessary to only provide in a suitable manner one particular coil, such as coil 23, in the portable device 20 for both power transmission to charge the battery power source 21 as well as for data communication to exchange various data with the power transfer device 10. In Fig. 3 the inductor Ll corresponds to the coil (loop coil) 23 of the portable device, and may have, for example, an inductivity of about 3 μH. At resistor Ra a 50 Ohm asymmetric port is provided, and the further inductor L2 (which may have an inductivity of 10 μH) only serves as a choke coil to decrease the loading on the 50 Ohm port. By means of a circuit arrangement as is for example shown in Fig. 3 the coil

23 of the portable device is driven in either case of data communication or power transfer. The coil (loop coil) Ll which corresponds to coil 23 of the portable device 20, is active when at terminal SV in Fig. 3 a higher voltage level (of for example +12 V) is applied. The diode D2 is conducting and diode Dl is off. The loop is tapped with capacitors towards 50 Ohm impedance to achieve matching to 50 Ohms. The coil Ll is not active and tuned to a lower frequency (which may have a value of about 3.6 MHz) when a lower voltage is applied to terminal SV (having for example -5 V). In this case, the diode D4 is non-conducting, and diode Dl is conducting and the capacitor Cl is switched in parallel to the coil Ll (loop coil, coil 23 of portable device 20). The voltages are controlled by the second controller 25 of the portable device 20.

In summary, the coil 23 of the portable device which is a single coil is used for both purposes of data communication and power transfer (via magnetic field from the power transfer device 10) and is depending upon the kind of link to be established (data communication link 32 or power transfer link 31) driven in a different and appropriate manner. The data communication link based on near field communication requires a tuning of the circuit and the coil (loop coil) 23 to the frequency range of about 13.56 MHz, whereas a frequency range for the power transmission can for example be about 460 kHz, or may have a range of approximately 430 kHz to approximately 1.8 MHz.

Since the data communication (such as for example radio frequency identification RFID) requires a different frequency range (standard) than the power transfer link 31 for transferring charging power from the power transfer device 10 to the portable device 20 for charging the battery power source 21 thereof, the circuit arrangement shown in Fig. 3 provides a different tuning or setting of the second controller 25 for driving the single coil 23 for the data communication link 32 based on near field communication (NFC) and for the power transfer link 31.

By using one and the same coil in the portable device 20 (coil 23 as shown in Fig. 2) the circuit arrangement can be simplified since the coils for power transfer or data transmission require coils with certain dimensions, and when using only one single coil for both purposes, this reduces the size of the portable device 20, the hardware and costs. That is, the coil which is usually used for providing a magnetic coupling to a wireless charging system is also used for establishing a data communication link, such as the data communication link 32 shown in Fig. 1 and 2, and can be further used for radio frequency identification RFID. When any portable device 20 the battery power sources of which have to be charged by a wireless charger such as the power transfer device 10 according to the present invention, and when a near field communication functionality is implemented in both devices, only one coil for the portable device to reduce the dimensions thereof is provided. Regarding the data communication, when both the power transfer device 10 and the portable device 20 have implemented therein the near field communication functionality (NFC functionality), then a predetermined data exchange can take place when the data communication link 32 has been established in a stable manner. When according to the near field communication standard (NFC standard) the data communication link 32 has been established, it is possible for the power transfer device 10 to identify the kind of portable device 20 and even a particular individual portable device, after establishing the data communication link 23 (when the portable device 20 is placed on or closely to the power transfer device 10), data stored in the portable device 20 can be transmitted from the portable device 20 to the power transfer device 10 via near field communication (data communication link 32) under control of the second controller 25 of the portable device 20 and by means of the magnetic coupling to the coil 23. The data transferred from the portable device 20 to the power transfer device

10 may include an identification number, an individual production number or any further predetermined data which allow an identification of a group of portable devices or an individual portable device (such as a mobile phone with NFC functionality). Moreover, an information about the charging conditions of the battery power source 21 of the portable device 20 can be transmitted to the power transfer device 10 to optimize the charging conditions (strength of the magnetic field generated in the power transfer coils 11 and 12) in view of voltage and current for charging the battery power source 21. In this connection, the individual portable device may send data regarding a particular charging condition or may submit data which allow the particular portable device 20 to be assigned to a certain category of charging conditions, such as, for example, category 1 : charge type IW, category 2: charge type 2W (fast charge), and category 3 : charge type xx W, indicating any further category.

Further identification data may be a brand name, a device type, a serial number and corresponding data. The transmitted information in the form of data may also include an information about communication ports available for the portable device 20, for example Bluetooth, IR, USB, and other corresponding communication ports. The transmitted data may further include the battery type as well as power coil dimensions which allow a suitable setting of the power transfer device 10 for optimize power transfer to the portable device 20. Such data can be stored in an appropriate storing means in the second controller 25 of the portable device 20 and can be provided according to a standardized format for such stored data so that easy data evaluation is possible when transmitted via the NFC functionality (data communication link 32) to the power transfer device 10, and in particular for handling of such data in the first controller 15 which receives the communication data via a magnetic coupling between the coil 23 of the portable device 20 and the communication coil 13 in the power transfer device 10.

Moreover, the first controller 15 of the power transfer device may temporarily store such data and may compare such data transmitted via the near field communication from the portable device 20 with data stored before hand in the power transfer device (in conjunction with the first controller 15) to determine an authorization for charging the specific portable device, or to determine further conditions, such as the allowance of further data transmission.

The transmitted data can be evaluated by the first controller 15 in the power transfer device 10 in view of plausibility, and for identification purposes particular data or values can be compared with prestored corresponding data and values in the power transfer device 10. In case of data matching identification can be performed and an authorization for further data transmission or for a subsequent wireless charging process can be determined. In this case, the controller 15 of the power transfer device 10 drives the power transfer coils 11 and 12 so that power can be transmitted via the generated electromagnetic field to the portable device and can be received by the coil 23 due to magnetic coupling. The battery power source 21 of the portable device 20 can be charged in a suitable and optimized manner by wireless charging.

The data stored in the portable device 20 and the data stored in the power transfer device 10 for the purpose of data matching and data evaluation can be programmed at the manufacturing process of the devices, where a suitable electronic chip (memory, tag IC) is programmed or written with corresponding data. After completion of the programming process at the manufacturer the electronic chip or memory should be set for "write protected" to avoid any later customer problems or accidental erasure of necessary data. Hence, such data support technical conditions or administrative conditions. When the portable device 20 is placed near or set on the wireless charger, such as the power transfer device 10 according to the present invention and both devices have NFC functionality, a quick establishment of the data communication link is carried out, thereby referring to the standard for NFC functionality (protocol). A corresponding data communication is shown in Fig. 4. The process includes plural steps for data communication and evaluation thereof.

When the portable device 20 is placed on the power transfer device 10, an automatic establishment of the data communication link 32 via NFC functionality is carried out (step Sl). When the data communication link 32 is established, according to step S2 an identification process regarding the portable device 20 in question is carried out, resulting in defining three categories of the kind of portable device 20.

In category A when proceeding from step S2 the portable device is according to step S 13 identified as a portable device having an NFC functionality so that a data communication link 32 via NFC and a subsequent power transfer link 31 (charging) can be established. In particular, after data communication is basically completed charging of the battery power source 21 of the portable device 20 can be carried out.

In step S 14 such an information can be displaced on a display means arranged on the portable device 20 and/or on the power transfer device 10 (not shown in the Figures) so that the user can be informed about the kind of portable device and the further operating conditions, that is, what kind of process is actually running.

In step S 15, after identification has been completed, data transmission as well as charging is allowed.

According to category B proceeding from step S2 in Fig. 4, it is identified a particular portable device 20 which has no NFC functionality so that any data communication and, thus, any identification regarding an individual portable device cannot be carried out. Hence, only a manual setting is possible (step S21). In step S22 such an information is displayed to inform the user about the detected conditions. After a corresponding manual setting of the power transfer device 20 by the user a charging operation can be carried out (step S23). According to category C when proceeding from step S2, in step S31 of Fig. 4 it is verified that the kind of portable device 20 placed on or near the power transfer device 10 has implemented an NFC functionality but requires no charging. According to step S32, such an information is displayed, and after an identification of the individual portable device 20 base on the NFC functionality, only data transmission is possible and can be carried out. No charging is performed, i.e. the power transfer coils 11 and 12 of the coil arrangement CA of the power transfer device 10 are not driven, and only the communication coil 13 is used and driven to establish and support the data communication link 32 via the NFC functionality. Category C is applicable in case a passive device such as a tag with NFC functionality is available having no individual power supply, or when for any other reasons any charging is not to be carried out or cannot be carried out due to technical reasons.

The display means of a portable device, not shown in the Figures, such as the display section of a mobile phone, may notify the user of any data detected or exchange or any prevailing conditions. Corresponding information can also be displayed on a display means of the power transfer device 10. Such an information may refer to the start and the end (completion) of the charging process, any feedback information about the actual battery status (state of charge of the battery), and when the portable device 20 is ready to initiate a rapid exchange of data (further data exchange) via a specific port, or may, for example, display any error messages helpful for the user.

The data handling and evaluation process and in particular the identification operation when the data communication link 31 has been established provides each of both devices involved with necessary or helpful data so that the identification operation helps to avoid that a non-compliant device is charged since charging a non-compliant device may lead to deterioration or malfunction thereof. Furthermore, a specific kind (brand) of power transfer device may not wish to charge specific or non-specific portable devices. The identification of the portable device by data exchange and data matching in the power transfer device 10 supports an adaptation of the behavior or service of the power transfer device 10 in view of specific charging parameters, data transfer conditions and specific services between the portable device 20 and the power transfer device 10.

In this connection, the power transfer device 10 in view of further and optimized data exchange and data evaluation can be connected to any local network (LAN) or any other computer system or host computer or server. This would extend or upgrade the services offered. The data communication can be carried out according to a certain identification protocol or data storage standard which has to be implemented in both controllers regarding the program (sequence of steps to be carried out) and the data format stored.

The protocol distinguishes between the priority of the two devices for which a data communication link is to be established, one device constituting the initiator and the other device constituting the target. In the present case the power transfer device 10 forms the initiator and the portable device 20 forms the target from which data are requested and from which upon output of a pertinent request such data are transmitted to the initiator (power transfer device 10). The data exchange may also be used for registration of individual portable devices 20 and for billing purposes according to the electric energy drawn from the charger in the form of the power transfer device 10 in public places (such as, for example, waiting rooms at the airport) or in view of the amount of data exchange in conjunction with the near field communication (NFC). Specific conditions such as time and costs or other information necessary or helpful for the user can be displayed.

In case of a connection of the power transfer device 10 to a computer, local network or host computer, depending upon the user's intention and in case the portable device 20 is provided in the form of a mobile phone, a time table, a calendar, an appointment book, a real time setting and other general notings can be transferred to and from the computer connected to the power transfer device 10 so that the user after charging and data communication of the mobile device can easily go over his notes in a computer connected thereto (such connection can be wireless or by cable).

The above-described embodiment of the present invention in conjunction with Fig. 1 to 4 facilitates the wireless power transfer to portable devices 20 when both the portable device 20 and the power transfer device 10 (charger) need to contain relative large coils to create the inductive link. In the portable device 20 one single coil is used for multiple purposes, that is for power transfer and for data communication, such as a near field communication (RFID) so that an additional coil to provide the NFC functionality is not necessary. Even the integration of two separate coils would in contrast thereto consume a large volume and would make the dimensions of the portable device 20 bigger and would raise the costs. Hence, the embodiment above exhibits the advantage of using an implemented power transfer coil in the portable device 20 in an efficient manner also for a data communication link (NFC functionality, RFID functionality).

Fig. 5 shows a second embodiment of the present invention. The schematic view shown in Fig 5 basically corresponds to the arrangement shown in Fig. 1 and 2, and the difference between the structure shown in Fig. 5 and that of Fig. 1 and 2 lies in the omission of a separately provided communication coil (communication coil 13 in Fig. 2) in the power transfer device 10. According to the second embodiment of the present invention the coil arrangement CA of the power transfer device 10 now includes a first coil 11 and a second coil 12 which serve for purposes of power transfer to a portable device 20 in the manner as described in conjunction with the first embodiment (power transfer link 31), and also for establishing a data communication link 32 based on NFC technology (NFC functionality). A coil 23 of the portable device 20 is identical to the coil 23 of the first embodiment and serves for power transfer from the power transfer device 10, as well as for establishing and supporting the data communication link 32. The first and second coils 11 and 12 of the coil arrangement CA of the power transfer device 10 according to the second embodiment of the present invention can also be used for the purposes of data transmission and power transfer so that the additional coil (communication coil 13 in Fig. 2) can be omitted.

The general function of the power transfer system according to the second embodiment is basically the same as that of the first embodiment with the exception that a circuit arrangement as shown in Fig. 3 for driving coil 23 which is used for data transmission and for power transfer and implemented in the second controller 25 of the portable device 20 is also implemented in the first controller 15 of the power transfer device to drive the first and the second coils 11 and 12.

The provision of one coil (for example the first coil 11 or the second coil 12 according to Fig. 5) of the power transfer device 10 makes it possible to arrange a plurality of such multi-purpose coils in the power transfer device 10 so that on the power transfer device 10 plural portable devices 20 can be placed for data communication and for charging purposes, if the individual properties of the portable device 20 allow or require charging.

Since in a similar manner as it is carried out according to the first embodiment and according to the second embodiment the identification of an individual portable device 20 is checked and allowance of further data communication or charging is permitted or not depending on the result of the identification process, the individual charging conditions or data transmission conditions can be set in the power transfer device 10 for optimized data communication and charging of the battery power source 21 of the particular portable devices 20. According to Fig. 5 the first controller 15 of the power transfer device 10 may have a drive circuit such as shown in Fig. 3 to drive the first and the second coils 11 and 12 of the coil arrangement CA. The structure in Fig. 5 only shows two coils, whereas depending upon the necessary size of the power transfer device 10 a higher number of coils, such as coils 11 and 12 can be implemented, and these plural coils are driven by a circuit as shown in Fig. 3. In this case the driving of the particular coils has to be controlled by the controller (first controller 15) and a continuous scanning of all coils is carried out so that every coil implemented is activated and driven as is explained above in conjunction with the circuit arrangement of Fig. 3. That is, in subsequent activation each coil is driven. Investigations reveal that in case it takes about 100 ms to activate each coil (loop coil) when driven by the first controller 15, and when it is assumed that the power transfer device 10 contains 16 individual coils, the scan repetition rate is 1.6 sec for all coils so that within this period of time each of the plurality of coils of the power transfer device 10 can be activated.

The different coils of the power transfer device 10 (see Fig. 2 and 5) of the coil arrangement CA are presented in these Figures in a schematic manner, and the coils can be provided in the power transfer device 10 representing the kind of charging pad within arrangement departing from that schematic representation shown in the Figures without deteriorating the function and advantages obtained by the power transfer system according to the present invention. In view of the power transfer link 31 for charging the battery power source of the portable device both devices have to be arranged very closely to each other, whereas the near field communication (NFC) can be established within a short distance range up to approximately 0.1 M. Hence, when the portable device 20 is placed on or closed to the power transfer device 10, the NFC distance is fulfilled.

Basically, the power transfer system according to the third embodiment of the present invention also involves a power transfer device 10 and a portable device 20 having a battery power source 21 and the possibility of obtaining a power transfer link 31 as well as a data communication link 32 based on near field communication (NFC functionality). In the third embodiment the power transfer device 10 as such, which receives power from a mains power supply PS such as a public power supply network, does not have an NFC functionality, but the NFC functionality is provided to the power transfer device 10 in the form of an NFC retrofit kit 40. This NFC retrofit kit is mounted to the power transfer device 10 in a mechanical manner to be close to the area or surface of the power transfer device 10 on which or closed to which the portable devices 20 are arranged or placed. The NFC retrofit kit 40 is in view of power supply and data transmission directly connected to the power transfer device 10 and is specifically linked with the first controller 15 shown in Fig. 2 and 5. Moreover, the NFC retrofit kit 40 includes the coil for only data transmission, so that a magnetic coupling is provided on the one hand between the power transfer coils of the power transfer device 10 for power transfer to the portable device, and on the other hand from the multi-purpose coil of the portable device 20 to the NFC retrofit kit 40 for data communication.

The further functions are the same as that of the first and second embodiments in view of data exchange and power transfer from the power transfer device 10 to the portable device 20 via the power transfer link 31. Based on the data exchange via the data communication link 32 based on NFC, the NFC retrofit kit 40 receives the data and supplies these data to the first controller 15 of the power transfer device 10, and is also able to transmit corresponding data to the portable device 20. Hence, in order to upgrade an existing power transfer device 10 having no

NFC functionality with an additional NFC functionality to exhibit the advantages presented above in conjunction with the first and second embodiments when a portable device in question is equipped with an NFC functionality, the NFC retrofit kit 40 can be supplemented. The advantages obtained are the same as discussed in conjunction with the first embodiment.

In the third embodiment the coils arranged in the power transfer device are only driven to provide and support the power transfer link 31 suitable for charging the battery power source 21 of the portable device 20. The additional provision of the NFC retrofit kit 40 makes it possible for the user to avoid any manual setting when charging of any portable device having NFC functionality is necessary and when a data matching in an identification operation can be determined.

Referring in general back to Fig. 4, regarding category A when proceeding from step S2 in Fig. 4, this case represents an active NFC mode of communication between the devices involved. It is assumed that the power transfer device 10 is the initiator of the near field communication (NFC) and starts communication at a selected transfer speed. The portable device 20 which is powered by the battery power source 21 receives the data or communication information transmitted from the power transfer device 10 and answers at the same transfer speed. Based on these initial steps the data transmission can be carried out until sufficient data are exchanged or data transmission is completed. Category C when proceeding from step S2 in Fig. 4 represents the passive

NFC mode which means that the portable device 20 is not powered by any individual battery power source. In this case, the initiator of the NFC which is assumed to be represented by the power transfer device 10 starts communication at a selected transfer speed. The portable device 20 not powered by any battery power source answers by using load modulated data at the same transfer speed upon reception of the data transmitted from the power transfer device 10.

It is further to be noted that the description of the power transfer system according to the present invention has been illustrated and described in detail in the drawings and the description above, but the illustration and description are considered to be illustrative or exemplary and are not restrictive. By contrast, the invention is not limited to the disclosed embodiments described above but can be varied within the scope of the appended claims.

Moreover, the method steps do not exclude other elements or steps covered by the scope of the appended claims and may be changed in their sequence without departing from the present invention. Furthermore, reference signs are not to be construed as limiting the scope.

Claims

CLAIMS:

1. Power transfer system, comprising power transfer device (10) and at least one portable device (20), said power transfer device including: at least one coil arrangement (CA) for generating or receiving a magnetic field, and a first controller (15) coupled to said coil arrangement for driving said coil arrangement to supply power to said portable device (20) placed on said power transfer device, via said generated magnetic field, said portable device (20) including: - a further coil (23) for generating and receiving a magnetic field, a battery power source (21), and a second controller (25) coupled to said further coil for supplying power received via said magnetic field generated by said power transfer device to charge said battery power device, wherein said first controller (15) and said second controller (25) being adapted to respectively drive said coil arrangement (CA) of said power transfer device (10) and said further coil (23) of said portable device (20) to establish between said power transfer device and said portable device a data communication link (32) based on near field communication for exchanging data, and a power transfer link (31) for supplying power to said portable device for charging said battery power source (21).

2. Power transfer system according to claim 1, wherein said data exchange between said portable device (20) and said power transfer device (10) includes data peculiar to the portable device.

3. Power transfer system according to claim 1, wherein said data exchange between said portable device (20) and said power transfer device (10) includes identification data of said portable device.

4. Power transfer system according to claim 1, wherein said second controller

(25) includes a driver circuit (26) for driving said further coil (23) to first establish said data communication link (32) and then establish said power transfer link (31).

5. Power transfer system according to claim 1, wherein said first controller (15) includes a driver circuit (26) for driving said first and second coils (16, 17) to first establish said data communication link (32) and then establish said power transfer link (31).

6. Power transfer device according to claim 1, wherein upon establishment of said data communication link (32) said second controller (25) of said portable device (20) being adapted to transmit identification data to said power transfer device (10) for a data matching, and upon verification of said identification said first controller (15) being adapted for starting wireless power transfer to the portable device (20).

7. Method of controlling a powered transfer system including a power transfer device (10) and at least one portable device (20), said powered transfer device including at least one coil arrangement (CA) for generating and receiving a magnetic field, and a first controller (15) coupled to said coil arrangement, for driving said coil arrangement to supply power to said portable device (20) placed upon said power transfer device, via said generated magnetic field, said portable device (20) including: a further coil (23) for generating and receiving a magnetic field, a battery power source (21), and - a second controller (25) coupled to said further coil for supplying power received via said magnetic field generated by said power transfer device, to charge that battery power source, said method comprising the steps of: driving said coil arrangement by said first controller and said further coil by said second controller to establish a data communication link based on near field communication, exchanging data between said power transfer device and said portable device by said data communication link, and driving said coil arrangement by said first controller and said further coil arrangement by said second controller to establish a power transfer link for supplying power to said portable device for charging that battery power source.

8. Method according to claim 7, wherein the step of exchanging data between said power transfer device and said portable device includes at least one of data peculiar to the portable device and identification data of said portable device.

9. Method according to claim 7, further comprising the steps of: transmitting, upon establishment of said data communication link, identification data to said power transfer device, carrying out a data matching on the basis of the identification data in said power transfer device by verifying said identification data, and starting the wireless power transfer to the portable device by the power transfer device.