This paper presents the analysis and design methodology for a LLC resonant converter controlled using two different control methods, switching frequency and VI (Variable Inductor). In order to compare both control techniques a battery charger is analyzed and simulation results are presented. In order to control the converter gain, the converter is regulated in the first case by varying the switching frequency and, in the second case, is regulated through a variable resonant tank. The design methodology is presented and simulation results were obtained and compared with the theoretical ones considering a simple battery charger application.