LLC Resonant Converter With Topology Morphing Rectifier for Wide Output Voltage Range Application

LLC is one of the most popular DC/DC converters in electric vehicle chargers, however, the change of state of charge requires output voltage range as wider as nearly four times between the upper and lower limits, and always forces the switching frequency to swing outside the preference region. Based on LLC resonant converter, a novel topology morphing rectifier, which can be operated either as full bridge rectifier or as voltage doubler rectifier, is proposed in this paper. This rectifier offers a cost and controllability competitive alternate for wide output voltage range applications. The average efficiency of prototype converter was measured to be more than 95% at a peak power of 0.5 kW, and furthermore the output voltage from 50V to 200V verified the concept of topology morphing.