Zero Voltage Switching Condition in Class-E Inverter for Capacitive Wireless Power Transfer Applications

Fabio Corti, Alberto Reatti, Ya-Hui Wu, Dariusz Czarkowski and Salvatore Musumeci
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Fabio Corti: Department of Information Engineering, DINFO, Università degli Studi di Firenze, 50129 Florence, Italy
Alberto Reatti: Department of Information Engineering, DINFO, Università degli Studi di Firenze, 50129 Florence, Italy
Ya-Hui Wu: Department of Electrical and Computer Engineering, NYU Tandon School of Engineering, New York, NY 11201, USA
Dariusz Czarkowski: Department of Electrical and Computer Engineering, NYU Tandon School of Engineering, New York, NY 11201, USA
Salvatore Musumeci: Energy Department, PEIC, Politecnico di Torino, 10129 Torino, Italy

Energies, 2021, vol. 14, issue 4, 1-20

Abstract: This paper presents a complete design methodology of a Class-E inverter for capacitive wireless power transfer (CWPT) applications, focusing on the capacitance coupling influence. The CWPT has been investigated in this paper, because most of the literature refers to inductive power transfer (IWPT). However, CWPT in perspective can result in lower cost and higher reliability than IWPT, because it does not need coils and related shields. The Class-E inverter has been selected, because it is a single switch inverter with a grounded MOSFET source terminal, and this leads to low costs and a simple control strategy. The presented design procedure ensures both zero voltage switching (ZVS) and zero derivative switching (ZDS) conditions at an optimum coupling coefficient, thus enabling a high transmission and conversion efficiency. The novelties of the proposed method are that the output power is boosted higher than in previous papers available in the literature, the inverter is operated at a high conversion efficiency, and the equivalent impedance of the capacitive wireless power transfer circuit to operate in resonance is exploited. The power and the efficiency have been increased by operating the inverter at 100 kHz so that turn-off losses, as well as losses in inductor and capacitors, are reduced. The closed-form expressions for all the Class-E inverter voltage and currents waveforms are derived, and this allows for the understanding of the effects of the coupling coefficient variations on ZVS and ZDS conditions. The analytical estimations are validated through several LTSpice simulations and experimental results. The converter circuit, used for the proposed analysis, has been designed and simulated, and a laboratory prototype has been experimentally tested. The experimental prototype can transfer 83.5 W at optimal capacitive coupling with operating at 100 kHz featuring 92.5% of the efficiency, confirming that theoretical and simulation results are in good agreement with the experimental tests.

Keywords: capacitive wireless power transfer; Class-E inverter; resonant converter; zero voltage switching (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (6)

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