A new bidirectional soft-switching multi-input dc-dc converter for automotive applications

In the next future, hybrid electric vehicles and electric vehicles will be more and more hybridized using different electrical storage devices. Traditionally in a vehicle having many energy storage systems, several independent power electronic converters were utilized. Due to their reduced part count, control simplicity and better efficiency, multi-input dc-dc converters seem to be a promising choice in hybridizing energy systems, therefore in literature many solutions have been proposed. In the paper, a new bidirectional soft-switching multi-input dc-dc converter for automotive applications is proposed. Such configuration is obtained as combination of two individual half-bridge dc-dc converters feeding a common dc bus. The soft-switch capability is achieved adding a simple auxiliary active clamping circuit for each leg. Such auxiliary circuit is operational regardless of boost or buck mode operation. The configuration guarantees fixed switching frequency, active clamped zero voltage switching operations of the main switches and bidirectional power flow. ZVS operations are guaranteed with wide load range. Reverse recovery effects are minimized and the drop voltage occurred over the switches is significantly reduced. In the paper the operating principle, soft-switching conditions and steady state analysis are presented. A 500 W prototype has been built and experimental results to verify the theoretical analysis are provided.