Design and Analysis of Modified Series–Parallel Quasiresonant Half-Bridge DC/DC Converter for Renewable Energy Applications

This article presents a half-bridge current-fed modified series–parallel quasiresonant dc/dc converter for renewable energy sources. A modified series–parallel resonant tank obtains partial resonance at on period of the semiconductor switches. As a result of the partial resonance, the switches experience natural commutation before the withdrawal of the gate signal. Thus, the semiconductor switches achieve zero current switching (ZCS) at a turn-
off
instant, which reduces the switching losses. Hence, the high-frequency operation is feasible, which improves the converter's efficiency and power density. In addition, high-frequency transformer, two boost inductors, and voltage doubler are used for higher voltage gain. In this converter, less frequency variation is required to regulate the constant output voltage over a wide range of load and input source variation. The voltage stress across each
mosfet
is lower compared to output voltage. Thus, the need for a snubber circuit is eliminated, and switches of low
$R_{\text{DS}(\text{on})}$
can be chosen for this converter. Due to common ground sharing, a high-side gate driver circuit is not required. In this converter, ZCS is obtained for varying input voltage and wide load ranges with less variation in the operating frequency. The performance of frequency-modulated converter is verified through laboratory testing of a 500-W hardware prototype. The steady-state waveforms and experimental results confirm the converter's proof of concept.