Article

Kontaktlose Energieversorgung mobiler Geräte durch induktive Nahfeldkopplung

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Abstract

Die kontaktlose Energieübertragung hat Dank ihrer Vorteile ein weites Anwendungsspektrum und wird seit Jahrzehnten mit Erfolg eingesetzt. Sie kann einerseits zur Steigerung des Kom-forts eingesetzt werden oder ermöglicht vollkommen neue Anwendungen. Dieser Artikel be-schreibt die physikalischen Grundlagen und die technischen Grenzen dieser Technologie. Es wird erklärt, warum heute die kontaktlose Energieübertragung nur auf kurze Distanzen effi-zient und sicher genutzt werden kann. Die Kombination von Leistungselektronik und digitaler Signalverarbeitung steigert dabei nicht nur die Energieeffizienz sondern ermöglicht auch die Bereitstellung einer stabilisierten Spannungsversorgung für das zu betreibende Gerät. Die physikalische Grundlage für die kontaktlose Energieübertragung im Nahfeldbereich ist entweder die kapazitive oder die induktive Kopplung. Die Ausgangsbedingungen für die kapazitive Energie-übertragung sind wegen des großen Unterschiedes zwischen Permeabilitäts-und Dielektrizi-tätskonstante wesentlich ungünstiger. Die bei kapazitiver Kopplung benötigten Treiberspannungen und Frequenzen führen bereits bei der Übertragung vergleichsweise niedriger Leistungen zu hohen Verlusten. Demgegenüber sind die zu überwindenden technischen Schwierigkeiten bei induktiver Kopplung weitaus geringer mit der Folge, dass induktive Energieübertragungssysteme deutlich effi-zienter sind.

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Chapter
In vielen Steuerungs-, Regelungs-, Überwachungs- und Abrechnungsprozessen muss eine Messgröße übermittelt werden, ohne dass ein Kabel zwischen der Auswerteelektronik und ihren zugehörigen Messwertaufnehmern gelegt werden kann oder soll. In diesen Fällen werden energieautarke, drahtlose Sensorsysteme (Funksensoren, engl. Transponder) eingesetzt, die von ihren Lesegeräten (engl. Reader) über eine Funkverbindung ausgelesen werden. In diesem Beitrag werden die unterschiedlichen Funktionsprinzipien funkauslesbarer Sensoren erläutert.
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