NONISOLATED MULTIPHASE HALF-BRIDGE-BUCK TOPOLOGY WITH INHERENT CURRENT SHARING CAPABILITY AND SOFT-SWITCHING AND COUPLED-INDUCTORS CURRENT-DOUBLER

Abstract

Point-of-load DC–DC converter requirements and design are increasingly becoming stricter than ever. This is due to the required tight dynamic tolerances allowed for supply voltages and high dynamic performance demand coupled with very high power density. Moreover, as the required converter output voltage becomes smaller, higher voltage step-down ratio is required, which results in smaller switching duty cycle in the nonisolated topologies. Step-down transformer with large turns ratio is used in the isolated topologies to step-down the voltage and keep larger duty cycle. Most of the nonisolated DC–DC topologies are buck-derived and unfortunately work at hard-switching which degrades the efficiency. DC–DC interleaved buck topologies were proposed but are highly sensitive to interleaved phases asymmetry and require high performance current sharing loop. In this paper, a nonisolated multiphase nonisolated half-bridge-buck topology is presented. This topology makes it possible to achieve soft-switching, works at larger switching duty cycle with lower output voltages, and does not require current sharing loop because of the inherent current sharing capability. Moreover, a coupled-inductor current doubler topology is also presented in this paper allowing higher step-down ratio and lower output current ripple. Theoretical analysis and experimental results are presented.