Voltage doubler application in isolated resonant converters

Two basic conditions of voltage-doubler adopted in isolated DC/DC converter are analyzed. According to the basic conditions, that voltage-doubler can be both adopted in LC series resonant converter and LLC multi-resonant converter. Operation characteristic of voltage-doubler adopted in isolated DC/DC converter is described in detail based on the analysis of voltage-doubler rectifying LLC multi-resonant converter. Advantages of voltage-doubler rectifying LLC multi-resonant converter are described in detail as follows, structure of transformer, in which one winding is involved on its secondary side, is simple, voltage stress of output capacitor is half of output and extra voltage balancing circuit is excluded. Two rectifier diodes are included on output end, voltage and current stress of diodes respectively equal output voltage and current. Therefore, the topology is a preferable candidate for such application as low-medium power level DC/DC converter with high output voltage. In addition, principle of automatic voltage balancing for output capacitor is presented, moreover design of key parameter is specified as well. Presented characteristics of the very topology are verified by a prototype, whose output is 500 V and efficiency of full load reaches 92.3%.