Capacitive Wireless Power Transfer System with Inductorless Receiver Side

Xu Chen*, Jiasheng Huang, Yi Dou, Zhe Zhang, Dennis Oland Larsen, Pere Llimos Muntal, Michael A.E. Andersen

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review


    In a capacitive wireless power transfer system, due to the pF-level coupling capacitance, resonant inductors are commonly used at the primary side to boost voltage and at secondary side to boost the current. However, the inductors are bulky, in particular when it comes to integration, thereby not preferred by some space-sensitive applications like smartphones, smart glasses and headphones. This paper proposes a capacitive wireless power transfer architecture with no inductors at the receiver side. A high conversion ratio step down switched capacitor converter (SCC-CPT), rather than inductors, is used to compensate for the impedance mismatch between the secondary side of the capacitive coupler and the load. The analysis method and its associated design procedure of the SCC-CPT system is developed with the target of clarifying the tradeoffs among the secondary side efficiency, coupler voltage stress, receiver side integrability, and the primary side compensation network gain. Finally, a 7.5 W, 12 MHz SCC-CPT prototype was constructed to validate the proposed analysis and design. The measured system efficiency is 75.6 % at 7.5 W output, and the secondary side switched capacitor converter efficiency is 96.4 %.

    Original languageEnglish
    JournalIEEE Transactions on Circuits and Systems I: Regular Papers
    Issue number3
    Pages (from-to)1372-1380
    Publication statusPublished - 1 Mar 2022


    • Capacitive wireless power transfer
    • Ladder topology
    • Switched capacitor converter


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