On Silicon-Integrated Micro-Transformers and Their Applications in Quasi-Resonant Flyback Converters

作者：Mengjie Cheng, Lei Liu, Zhenyu Liao, Junchao Yu, Shanfeng Peng, Zhengmin Zhang, Tincong Ye, Ningning Wang · 发表于：IEEE Transactions on Magnetics · 年份：2022 · DOI：10.1109/tmag.2022.3166696 · 被引用次数：10 · 研究领域：Advanced DC-DC Converters、Silicon Carbide Semiconductor Technologies、GaN-based semiconductor devices and materials

This article has shown the design and characterization of silicon-integrated thin-film micro-transformers and their application in a quasi-resonant flyback converter. Two micro-transformers with different turn ratios of 4:4 and 3:3 were designed. The micro-transformers in this study have elongated spiral shape windings sandwiched between two layers of the thin-film magnetic core, and this structure can leverage the anisotropic core property. The micro-transformers were built on a silicon substrate using micro-electro-mechanical systems (MEMSs) fabrication process to ensure a high integration level and high power density. The inductance of 4:4 and 3:3 micro-transformers are 57.3 and 31.5 nH, respectively, their coupling coefficients are 90.5% and 82.7% at 30–40 MHz, and the measured quality factors are 7.82 at 21 MHz and 8.94 at 35 MHz, respectively. A resonant flyback converter topology deploying with a high electron mobility transistor [Gallium nitride (GaN)] was used to evaluate the electrical performance of two micro-transformers. Two resonant flyback converters operating at zero voltage switching (ZVS) reached the maximum conversion efficiency of 46.4% (3:3) and 45.7% (4:4), respectively, with 3.3 V input. The 3:3 micro-transformer developed in this work achieved the highest power density of 128 mW/mm2with a similar efficiency compared to other cored micro-transformers. The loss analysis of the flyback conversion circuit shows that the main losses in the circuit are the c...