Bidirectional Power Flow Control in a DC Microgrid Through a Switched-Capacitor Cell Hybrid DC-DC Converter

This paper focuses on a bidirectional hybrid dc-dc converter suitable as an interface between two dc voltage buses in various applications including microgrids. The switched-capacitor cell, incorporated in the converter topology, gives the advantage of high voltage conversion ratio without using a transformer. This paper analyses the converter operation and the stability in the step-up and stepdown operating modes through the state-space averaging method and through the pulse width modulation switch model method applied on an equivalent circuit model. The converter employs a current controller designed in frequency domain based on the Bode plot, using the K factor method. The simulation results obtained by means of an average and a detailed switching model prove, in good correspondence, that the controller is able to track the reference current waveform with good dynamic performance. Experimental results obtained from a 2 kW converter prototype confirm the theoretical considerations and the simulation results.