Hybrid Modulated Bidirectional Resonant DC/DC Converter for High-Voltage Bus-Based Energy Storage Systems

In high-voltage bus-based energy storage systems, an isolated bidirectional dc/dc converter is required to link the low voltage energy storage unit and the high-voltage bus. This paper proposes a series resonant dc/dc converter for this specific application. In the proposed converter, the step-up ratio is boosted by an active voltage quadrupler rectifier on the high voltage side. Thus, a transformer with a moderate turns ratio can be employed. Moreover, the voltage stresses of high voltage side MOSFETs are significantly reduced in comparison with conventional active rectifiers. This facilitates an easier selection of low-cost and highly-reliable Si MOSFETs. To optimize the converter performance, a unique phase-shift and frequency hybrid modulation scheme are proposed. The frequency modulation tightly regulates the output power, while the phase-shit modulation minimizes the conduction loss. A 500 W converter prototype, linking an 80 V-120 V battery pack and 760 V dc bus, is designed and tested to verify the concept.