Open AccessAdjusting the frequency of an autonomous push–pull converter for wireless power transfer through a voltage-controlled variable capacitor structure
Author(s) -
Jie Tian,
Patrick Hu
Publication year - 2017
Publication title -
wireless power transfer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.275
H-Index - 11
ISSN - 2052-8418
DOI - 10.1017/wpt.2017.3
Subject(s) - variable capacitor , capacitor , capacitance , wireless power transfer , electrical engineering , voltage , maximum power transfer theorem , inductor , power (physics) , engineering , physics , electromagnetic coil , electrode , quantum mechanics
This paper proposes a Voltage-controlled Variable Capacitor Structure (VVCS) to adjust the frequency of an autonomous push–pull converter. Unlike traditional switch mode capacitors or inductors where active switches are used, the equivalent capacitance of the VVCS varies with the on/off periods of a diode controlled by a DC voltage. The frequency of the autonomous push–pull converter can be controlled by this DC voltage when the VVCS is used as a variable resonant capacitor. As no active switching is involved in the VVCS, the circuit operates more smoothly than its switch mode counterpart so as to provide a simple way to adjust the operating frequency of the autonomous push–pull converter for high frequency and low electro magnetic interference operations. Mathematical model is developed for the relationship between the equivalent capacitance of the VVCS and the DC control voltage, and is verified by experimental results at more than 900 kHz with an approximately 12 W inductive power transfer system.