Analysis and design of a high frequency isolated full bridge CLL resonant DC-DC converter for renewable energy applications

In this paper, a new PWM gating scheme is proposed for fixed frequency full-bridge DC-DC CLL resonant converter with capacitive output filter. An approximate complex ac circuit approach is used for the steady state analysis of the converter. The optimum design of the converter is described with the help of design curves for a sample converter of rating 200 W, 40-80 V DC input and output DC voltage of 200 V. By applying the proposed gating scheme, higher conversion efficiency is obtained due to zero-voltage-switching of the converter switches for wide variations in input voltage and the load. PSIM simulations are performed to verify theoretical predictions about the performance of the converter for variations in load and input voltage. The theoretical and simulation results are given and discussed.