· · · Repository hosted by TU Delft Library

Wireless power transfer allows a convenient, easy to use battery charging of mobile phones and other mobile devices. No hassle with cables and plugs, just place the device on a pad and that’s it. Such asystem even has the potential to become a standard charging solution. Where are the limits for such a solution and which are the side conditions to consider? What are the possibilities to realize such a system? To make the whole idea a success, it is definitely necessaryto come to widely accepted standard. Therefore, in 2009 the WirelessPower Consortium was founded with meanwhile more than 60 internationalcompanies as members. The consortium recently released the first worldwide standard on wireless power for mobile devices of to 5W. The contribution presents details of this standard and the rationale behind.

This report summarizes the activities related to the public funded project “Vollintegrierte leistungselektronische Systeme in der Automobilelektronik – VISA” (Fully Integrated Power Electronic Systems in Automotive Electronics). Aim of the project is to investigate the integration of components into printed circuit boards (PCB) for automotive power applications. For Philips, this technology is interesting for integrated LED drivers as used e.g. in automotive head lamps. The project is funded by the German government BMBF under Förderkennzeichen (funding number) 13N9698 and run 3 years from 1.May 2008 until 30.April 2011. It is run by a consortium of the following project partners: Conti Temic microelectronic GmbH (coordinator), Philips Technologie GmbH Forschungslaboratorien, VAC Vacuumschmelze, Schweizer Electronic AG, Chemnitzer Werkstoffmechanik GmbH, Fraunhofer PYCO Teltow, Technische Universität Berlin, RWTH Aachen ISEA and the associate partner Daimler AG. The contributions by Philips Research to the project are to derive a circuit concept and create a demonstrator circuit for an automotive LED headlight driver. Further contributions are the design of integrated magnetic components and the characterization of related soft-magnetic materials. For the LED driver, a resonant converter is selected to minimize switching losses. The demonstrator driver is built as a multilayer PCB with functional layers. It includes winding and soft-magnetic layers for the inductive component and PCB integrated power FETs. The 15W converter has a size of 34 mm x 66 mm with PCB thickness of about 4 mm. It converts an input voltage of 9 V to 18 V to the output of 1 A and about 15 V. The losses are mainly determined by the magnetic component, which are still too high because of the limited properties of the PCB integrated soft-magnetic material. To investigate the properties of soft-magnetic layers, a measurement setup is designed and built, which is used to measure the magnetic permeability of thin layers. 47 samples of Ferrite Polymer Compound (FPC), which were manufactured by the project partner PYCO, are characterized. It was possible to improve the magnetic permeability to μr = 40 and still using PCB compatible polymers. Metallic particles of a material delivered by the partner VAC are used. Furthermore, a measurement setup to measure magnetizing losses is designed and built in cooperation with the partner ISEA. Only the most interesting samples of FPC are characterized. It showed that magnetizing losses could not be improved compared to materials existing before. Concluding, the technology of PCB integration is promising, but the materials needed for a commercial application of this technology need to be developed further.

In inductive wireless power transmission system a lateral displacement of the receiver coil to the transmitter coil leads to a change ofthe coupling factor and thus an unwanted variation of the power transfer. Here, an algorithm to determine the turn distribution to achieve homogeneous coupling between coils of different diameter is described. As long as the coils overlap, the variation of the coupling factor is very low. To achieve a lateral displacement over an even larger area, an array of transmitter coils can be used. The size of the receiver coil is selected such that it always covers a complete transmitter coil. If only the covered transmitter coil is activated by a suitable detection circuit, the power transmission area can be arbitrary large with homogeneous magnetic coupling.

Um die mobile Geräte wie z.B. Mobiltelefone, Music-Player, Digitalkameras Kommunikationsmittel mit Energie zu versorgen, wird gerade fürMassenanwendungen in letzter Zeit häufig induktive kontaktlose Energieübertragung vorgeschlagen. In diesem Artikel werden nun Limitierungen in Hinblick auf die Energie-Effizienz solcher Systeme untersucht. Als Schlussfolgerung ist festzuhalten, dass induktive Energieübertragung in einen größeren Raum (z.B. in einem ganzen Zimmer) sehr ineffizient ist. Hingegen kann induktive Energieübertragung an einer Oberfläche so effizient wie konventionelle Stromversorgungen sein. Darauf basierend wurde ein Pad zur induktiven Energieübertragung entworfen und gebaut, mit dem Ziel, die Batterien von Mobilgeräten aufzuladen. Es kann eine beliebige Anzahl von Geräten aufladen und erlaubteine freie Positionierung auf dem Pad. Um eine genügende kommerzielle Basis für ein solches Produkt zu schaffen, wurde das „Wireless Power Consortium“ gegründet mit Ziel, einen internationalen Industriestandard zum kontaktlosen Laden von Mobilgeräten zu schaffen.

Wireless power transfer by magnetic induction offers a simple to use way to recharge mobile devices like e.g. mobile phone, music players or medical sensors. As shown by a previous report and an existing Power Pad demonstrator, wireless inductive power transfer is possible with a good power efficiency and low magnetic radiation only on a surface and with local activation underneath the mobile device. However, compared to the existing Power Pad, an improved detection method for the local activation is needed. This report investigates the use of RF-ID tags for the position detection. It addresses the problem to multiplex the RF-ID signal to a number of neighboured powercells to locate the device and the simultaneous transfer of power and information. To investigate the solution, a demonstrator is designed and built. This first circuit can activate 4 neighboured and overlapping cells. The circuit consists of a NFC/RF-ID PN511 con-troller by NXP, an analogue multiplexer to direct the RF-ID signal to the cells and FETs as switches to switch the power signal to each cell. The system operates at 500 kHz for the power transmission and at 13.56 MHz for the RFID data transmission. The circuit is controlled by an external computer using a dedicated software developed with LabView.