An AC Processing Pickup for IPT Systems

This paper presents a new type of inductive power transfer (IPT) pickup that directly regulates the power in ac form, hence producing a controllable high-frequency ac source suitable for lighting applications. The pickup has significant advantages in terms of increasing system efficiency, reducing pickup size, and lowering production cost compared to traditional pickups that also produce a controlled ac output using complex ac-dc-ac conversion circuits. The new ac processing pickup employs switches operating under zero-voltage-switching conditions to clamp parts of the resonant voltage across a parallel tuned LC resonant tank to achieve power regulation over a wide load range. The operation of the pickup is analyzed and the circuit waveforms have been verified by experimental results. A complete IPT system using the ac processing pickup was tested on a 500-W lighting system and an efficiency of 96% was obtained when delivering 500 W to multiple resistive light bulbs.