A novel LLC resonant converter for wide input voltage and load range

Nowadays, some applications require high efficiency under wide load range and wide input variation. In order to get high voltage gain characteristics in a wide input and load ranges, the conventional LLC resonant converter requires a small magnetizing inductance, and a lot of losses by the higher magnetizing current can be generated in the switches and transformer. The proposed LLC resonant converter with two resonant tank circuits and auxiliary switches, even though large magnetizing inductance of the transformer is used, can get the high voltage gain characteristics in a wide input voltage and load ranges. Also, due to the reduced magnetizing current, losses and efficiency characteristics can respectively be reduced and improved. The proposed LLC resonant converter is described and verified through a 500W experimental prototype.