Multi‐megahertz quasi‐square‐wave flyback converter using eGaN FETs. Issue 10 (14th June 2017)

• Record Type: Journal Article
• Authors: Zhang, Zhemin; Ngo, Khai D.T.
• Is Part Of: IET power electronics. Volume 10:Issue 10(2017)
• Page Start: 1138
• Page End: 1146
• Publication Date: 2017-06-14
• Subjects: zero voltage switching -- switching convertors -- field effect transistors -- gallium compounds; multimegahertz quasi‐square‐wave flyback converter -- FET -- constant frequency ZVS quasi‐square‐wave mode -- telecommunication application -- charge conservation method -- capacitor nonlinearity -- soft switching -- leakage inductance -- eddy losses -- parasitic capacitance -- high‐frequency PCB windings -- nickel‐zinc ferrite material -- finite‐element simulation; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2016.0782
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : As the fast development of the better figure‐of‐merits gallium nitride (GaN) devices, the switching frequency of isolated flyback converter could be pushed to multi‐megahertz to evaluate the improvement of the power density. A constant frequency zero‐voltage switching (ZVS) quasi‐square‐wave (QSW) mode is applied to the 30 W flyback in telecommunication application, and a charge conservation method including capacitor non‐linearity is proposed to design the coupled inductors for soft switching over entire input and load range. Leakage inductance, eddy losses and parasitic capacitance were quantified and optimised in the design of high‐frequency PCB windings. A 98% coupling planar‐coupled inductors by utilising nickel‐zinc ferrite material with EI‐shaped core were designed by finite‐element simulation. To validate all the analysis, a 30 W flyback converter was fabricated and measured with peak efficiency of 90.6% operating at 5 MHz. The coupled inductors consumed almost 2.5% of the output power with the area of 180 mm 2 occupied 30% of the power stage.