A fixed-frequency LCL-type series resonant converter with capacitive output filter using a modified gating scheme

A fixed frequency, modified (or LCL-type) series resonant converter (SRC) with capacitive output filter using a modified gating scheme is proposed. Steady-state analysis of the converter using approximate complex ac circuit analysis method is presented. Based on the analysis, a simple design procedure is given and illustrated with a design example of a 22 to 41 V DC input, 1 kW, 380 V. Due to the increased number of switches operating with zero-voltage switching, this converter with the modified gating scheme gives higher efficiency as compared to that with the regular phase-shift gating scheme. With minimum input voltage this converter requires a narrow variation in pulse-width for a wide variation in the load current while the peak current through the switches decrease with the load current. Detailed PSIM simulation results are presented to substantiate the performance of the designed converter for varying input voltage and load conditions. Also, an experimental converter of input voltage 50 to 100 V, 200 W, 200 V has been built and waveforms obtained using the experimental setup are presented.