A Nonisolated ZVS Asymmetrical Buck Voltage Regulator Module With Direct Energy Transfer

This paper presents a new nonisolated asymmetrical buck voltage regulator module. A transformer is used to extend the extremely low duty cycle of a conventional buck converter. Turn-off losses can be significantly reduced due to the extension of duty cycle, and there are no turn-on losses owing to the zero-voltage turn-on condition. At the same time, the voltage stress over the synchronous rectifier MOSFETs is also reduced. Therefore, the reverse-recovery losses of the body diode can be reduced. Furthermore, the MOSFETs with lower voltage rating and lower R-DS(on) can be used to reduce the conduction losses. In order to reduce the turn-off losses above the switching frequency of 1 MHz further, a new current-source driver is also proposed, which is suitable to this new topology. A 12-V input prototype with the switching frequency of 1 MHz was implemented. Simulation and experimental results verify the functionality and benefits of the proposed topology.