Analysis and Design of Load-Independent Series Resonant Power Amplifier With Constant Current Output and Its Application for WPT System

• Published in: IEEE transactions on power electronics Vol. 39; no. 5; pp. 6515 - 6525
• Main Authors: Komiyama, Yutaro, Komanaka, Ayano, Zhu, Wenqi, Konishi, Akihiro, Nguyen, Kien, Sekiya, Hiroo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Constant current (CC); Design analysis; Harmonic analysis; Harmonic distortion; Inductance; inverse class e amplifier; Load fluctuation; Load resistance; load-independent (LI); Power amplifiers; Power harmonic filters; Reactance; Rectifiers; Switches; Switching frequency; total harmonic distortion (THD); Voltage; wireless power transfer (WPT); Wireless power transmission; Zero current switching
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2024.3367373

This article presents an analysis and design of a load-independent (LI) series resonant (SR) power amplifier with constant current (CC) output, along with its application for an MHz wireless power transfer (WPT) system. A novel inverse Class E power amplifier is introduced, which essentially produces a sinusoidal output current even with a low-<inline-formula><tex-math notation="LaTeX">Q</tex-math></inline-formula> SR filter. Besides, the proposed amplifier achieves zero-current switching and CC output simultaneously, regardless of the load resistance. The LI operation is obtained for a specific set of component values, whose design conditions are clarified analytically in this article. The experiment was carried out with a WPT system incorporating the proposed amplifier as a transmitter and the Class D rectifier as a receiver. Although the input reactance of the Class D rectifier changed against dc-load variations due to the parasitic capacitances, the proposed amplifier showed consistent CC operation by using the low-<inline-formula><tex-math notation="LaTeX">Q</tex-math></inline-formula> SR filter. Also, the proposed WPT system maintained a low total harmonic distortion of the transmission current over the wide load range, even with the low-<inline-formula><tex-math notation="LaTeX">Q</tex-math></inline-formula> output filter. The prototype WPT system with the proposed amplifier achieved 88% power-delivery efficiency with 60 W output power at 3.39 MHz transmission frequency. The experimental results showed the effectiveness of the proposed amplifier.