Abstract: Methods and systems for controlling an output voltage of a resonant converter during a light load condition. One such method includes generating a normalised conduction time of the resonant converter that varies inversely with a switching frequency of the resonant converter by continuing to operate the resonant converter in a Pulse Frequency Modulation mode at a low switching frequency that is similar to the resonant frequency. The method also includes controlling a power level delivered to a secondary winding of a transformer positioned between a resonant tank and an output rectifier of the resonant converter by regulating the normalised conduction time, where the delivered power level is variable based on load conditions. The method further includes generating an output voltage using the output rectifier wherein the magnitude of the output voltage corresponds to the power level delivered to the secondary winding.

Abstract: Methods and systems for balancing output currents of parallel connected resonant converters are disclosed. One such method includes matching switching frequencies for a pair of resonant converters. The method also includes carrying AC output currents of resonant tanks of each of the resonant converters through a current controlled voltage source that is coupled to each of the resonant converters of the pair of resonant converters at an AC side of each of the resonant converters of the pair of resonant converters. The method further includes inducing, for the pair of resonant converters, a voltage that is proportional to a difference in the AC currents carried through the current controlled voltage source by passing the AC currents through the current controlled voltage source. The induced voltage is oriented to oppose the greater of the AC currents and to increase the smaller of the AC currents.