DC-DC Bidirectional 4-Switch Cúk Converter with Voltage-Doubler Concept for Interfacing Batteries in Microgrids

This paper presents the theoretical analysis and design equations of a dc-dc bidirectional Cúk converter with voltage-doubler concept. The converter is suitable for connecting a battery energy storage system in a dc microgrid. Due to the voltage-doubler concept, the voltage stress on semiconductors is reduced by a factor of two, when it is compared with the conventional Cúk converter. Moreover, due to the input and output current source characteristics, the converter presents advantages as draining/injecting currents of the dc microgrid and charging/discharging the battery energy storage system with low-ripple currents. Furthermore, the theoretical analysis is verified by experimental results, which are obtained from a converter with 250 V in input voltage, 360 V in output voltage, 1000 W rated power and 20 kHz switching frequency.