Novel Four-Port DC–DC Converter for Interfacing Solar PV–Fuel Cell Hybrid Sources With Low-Voltage Bipolar DC Microgrids

Abstract

Bipolarity in dc microgrids is desirable as it enhances the system reliability and efficiency. However, a bipolar dc microgrid (BDCMG) demands multiple conventional dc-dc converters to feed power to both the poles of the BDCMG. To handle this requirement and to maintain high efficiency, a new four-port, dual-input-dual-output dc-dc converter topology is proposed for interfacing the solar photovoltaic (PV) and fuel cell sources to a low-voltage BDCMG. The proposed topology is unidirectional, efficient, and compact. It has fewer circuit elements with only one inductor compared to the conventional nonisolated dc-dc converters. The proposed converter regulates one of the pole voltages of the dc bus and also ensures maximum power point tracking of the PV source. Furthermore, the converter can be operated as a single-input-dual-output converter. The control complexity of the proposed converter is low as it can be operated in various modes with only one set of controllers. To design the control system for the proposed converter, a small-signal model is derived for each operating mode. Loss modeling and efficiency analysis of the proposed converter are carried out, and its efficacy and performance are validated by detailed simulation and experimental results under various operating conditions.