Capacitive Wireless Power Transfer System With Inductorless Receiver Side

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 pr...

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Bibliographic Details
Published in:IEEE transactions on circuits and systems. I, Regular papers Regular papers, 2022-03, Vol.69 (3), p.1372-1380
Main Authors: Chen, Xu, Huang, Jiasheng, Dou, Yi, Zhang, Zhe, Larsen, Dennis Oland, Llimos Muntal, Pere, Andersen, Michael A. E.
Format: Article
Language:English
Subjects:
Capacitive wireless power transfer
Capacitors
Conversion ratio
Couplers
Couplings
Design analysis
Efficiency
Electric potential
Impedance
Inductors
ladder topology
Receivers
Resistance
Smartphones
switched capacitor converter
Topology
Voltage
Wireless power transmission
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Summary: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 %.
ISSN:1549-8328
1558-0806
DOI:10.1109/TCSI.2021.3135458