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

摘要： 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 bipolar dc grid. To handle this requirement and to maintain high efficiency, a new four-port, dual-input-dual-output (DIDO) converter topology is proposed for interfacing the solar PV and fuel cell (FC) sources to a low-voltage BDCMG. The proposed topology is unidirectional, efficient, and compact. It has fewer circuit elements with only one inductor as compared to the conventional non-isolated dc-dc converters. The proposed converter regulates one of the pole voltages of the dc bus and also ensures MPPT of the PV source. Further, the converter can be operated as a single-input-dual-output (SIDO) 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 modelling 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.