High efficiency single-stage llc resonant converter for wide input voltage range

Abstract

In this paper, a new single-stage LLC resonant converter with relay for wide input voltage is proposed. According input voltage, connection of proposed converter is changed by relay. According to input voltage, turn ratio of proposed converter is changed. Lm of proposed converter is designed higher than conventional converter. Proposed converter is operated series connection at high input voltage. Proposed converter has lower peak of magnetizing current and lower primary RMS current at high input voltage. So proposed converter has low conduction loss and low switching loss at high input voltage. Proposed converter is operated parallel connection at low input voltage. Proposed converter has lower resistance of primary wire of transformer at low input voltage. So proposed converter has low conduction loss at low input voltage. The feasibility of the proposed converter was verified by experimental results with a prototype of 60W, 90Vac~264Vac input, and 16.5V- 3.65A output. The proposed converter shows high efficiency, low cost and similar size than conventional converter.