A simple structure of LLC resonant DC-DC converter for multi-output applications

Multi-output LLC resonant topologies with asymmetrical structures dedicating to multi-output power supply systems, having limitation of lowest load, are presented in this paper. According to output power level, different configuration of secondary output end can be flexibly adapted. Consequently, the presented topology is a favorable candidate for such application as whose outputs are not symmetrical, i.e. compared with auxiliary output, power level of main output is comparatively higher. In addition, all switches of the very topology operate under the condition of ZVS and therefore it is applicable to such occasion as high frequency, high power density. Asymmetrical operating principle and ZVS operation are analyzed in detail, moreover key parameter design considerations are presented. Finally, the analysis above is verified both by simulation and experiment.