Variable-Frequency Pulse Width Modulation Circuits for Resonant Wireless Power Transfer

Li-Chuan Tang, Shyr-Long Jeng, Edward-Yi Chang and Wei-Hua Chieng
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Li-Chuan Tang: Department of Mechanical Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Shyr-Long Jeng: Department of Mechanical Engineering, Lunghwa University of Science and Technology, Taoyuan City 333326, Taiwan
Edward-Yi Chang: Department of Material Science and Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Wei-Hua Chieng: Department of Mechanical Engineering, College of Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan

Energies, 2021, vol. 14, issue 12, 1-25

Abstract: In this paper, we develop a variable-frequency pulse width modulation (VFPWM) circuit for input control of 6.78-MHz resonant wireless power transfer (WPT) systems. The zero-voltage switching control relies on the adjustments of both duty cycle and switching frequency for the class-E amplifier used in the WPT as the power transmission unit. High-frequency pulse wave modulation integrated circuits exist, but some have insufficiently high frequency or unfavorable resolution for duty cycle tuning. The novelty of this work is the VFPWM circuit design that we put together. A voltage-controlled oscillator (VCO) of radio frequency and capacitor-coupled difference amplifiers are used to simultaneously perform the frequency and duty cycle tuning required in resonant WPT applications. Different circuit topologies of VFPWM are compared analytically and numerically. The most favorable circuit topology, enabling independent control of the frequency and duty cycle, is employed in experiments. The experimental results demonstrate the validity of the novel VFPWM, which is capable of operating at 6.78-MHz and has a duty ratio adjustable from 20% to 45% of the range applicable in the resonant WPT applications.

Keywords: wireless power transfer (WPT); class-E amplifier; voltage-controlled oscillator (VCO); variable-frequency pulse width modulation (VFPWM); difference amplifier (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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