Isolated High Step-Up DC-DC Converter Based on Quasi-Switched-Boost Network

In this paper, a new isolated high step-up dc-dc converter is proposed based on the quasi-switched-boost network. The proposed converter has the following features: 1) continuous input current; 2) reduced turn ratio of the isolated transformer; 3) increased reliability, as it can operate in either short-circuit mode or open-circuit mode without causing damage to the power converter; and 4) unchanged primary and secondary voltage waveforms of the transformer, although the shoot-through duty cycle is variable. Compared to the quasi-Z-source-based isolated dc-dc converter, the proposed converter uses fewer passive components. The operating principles, analysis, parameter design guideline, and comparison with the quasi-Z-source-based isolated dc-dc converter are presented. A 450 W prototype is built to test the proposed converter. The proposed converter is applicable for distributed power generation applications where a varying low dc input voltage is converted to a high stabilized dc output voltage with a galvanic separation requirement.