LLCC Resonant Converter With Wide ZVS Range and Low Voltage and Current Stress

To address the problems of narrow soft-switching range and high voltage/current stress on resonant components in LCC resonant converters operating in phase-shift control mode, this article proposes a LLCC resonant converter with wide soft-switching range and low voltage/current stress. The converter adds a parallel auxiliary inductor at the input of LCC resonant tank, which widens the zero voltage switching range of the converter in phase-shift control mode and reduces the current stress on the resonant inductor. Meanwhile, the series-parallel resonant capacitors are designed on the low-voltage side of the converter, and the voltage stress on the resonant capacitors is lower than that of the traditional LCC resonant converter under the same operating conditions. In addition, improved fundamental harmonic approximation is used to model the steady state operating process of the LLCC resonant converter, and a set of parameter design scheme is given in the article. The value of the filter inductor obtained by this scheme is smaller, and the power density and dynamic response performance of the converter are better. Finally, a 500Wprototype is built, and the feasibility and effectiveness of the LLCC resonant converter and the design method are verified through simulation and experiment.