DC-DC converter implementation with wide output voltage operation

A direct current (DC) to DC converter with soft switching and high efficiency is developed for industry power units with a wide range of output voltage applications. A series resonant converter is the main circuit on the primary side to accomplish the soft switching characteristics for the active devices and rectifier diodes without switching loss or reverse recovery current loss. To overcome the drawback of the limited operation input or output voltage range in conventional LLC converters, a hybrid resonant converter including a half-bridge circuit and a full-bridge circuit with auxiliary windings is developed to achieve 8:1 (V-o,V-max = 8V(o,min)) output voltage characteristics for a wide range of output voltage applications. To achieve this function, two AC power switches are used in the developed circuit. Since a single-stage hybrid resonant converter is presented instead of a two-stage converter to realize wide voltage range operation, the developed circuit has better efficiency when compared to conventional LLC converters and two-stage DC-DC converters. To confirm the circuit analysis and effectiveness, a prototype with a 400 W rated power was built and tested.