A Novel Full-Bridge Boost LCL-Type DC/DC Converter With a Constant Off-Time: Analysis, Design, and Experimental Results

This article presents a full-bridge boost LCL-type dc/ac/dc converter with an isolation transformer. In the proposed converter, the output voltage is regulated by controlling frequency with a constant turn-off time of the switches. Traditional capacitor works under resonant function so that the dc-bus capacitor is eliminated. Under this design, the converter works under zero voltage switching condition in the entire operation range without auxiliary circuits. To minimize the energy dissipation, the waveform of the tank voltage has been modulated. A Fourier's mathematical description is exploited to help the design, and detailed power simulation (PSIM) results are presented to verify the performance of the designed converter at varied input voltage. Additionally, a laboratory prototype converter with 50−162 V input and 200-V/400-W output is built to confirm the proposed design. The experimental results show that the converter has a wider input-voltage range with a narrow switching frequency range.