Analysis and Reliability Evaluation of a High Step-Up Soft Switching Push–Pull DC–DC Converter

摘要

In this article, a new soft switching isolated push–pull dc–dc converter using a three-winding transformer is proposed. The proposed hybrid resonant and pulse width modulated converter employs a conventional push–pull structure in the primary side, a voltage doubler in the secondary side, and a bidirectional switch besides the transformer, altogether help offering a high efficiency over a wide range of input and output voltage signals with an unsophisticated fixed-frequency control mechanism. The primary-side switches are commutated under zero voltage switching with low switching current and the secondary-side diodes are commutated under zero current switching. In this article, we first present an in-depth analysis of various operation modes and design constraints. Our analysis is further complemented with a comprehensive reliability evaluation of the proposed converter under various short circuit and open circuit fault scenarios. Different from the previous research, the derated operating states of the proposed converter are detailed and characterized in the reliability evaluations. A comparison study is then provided to evaluate the performance of the proposed converter against other similar converters from the operation, components count, efficiency, and reliability perspectives. Finally, the theoretical analyses are verified via tests and experiments performed on a 280?W/34.7?kHz prototype.