A three-port three-phase isolated DC-DC converter feasible to PV connection on a DC distribution system

This paper presents a current-fed three-phase, three-port dc-dc converter with high-frequency isolation and bidirectional capability. Port I is fed by a battery bank, port II employs a set of photovoltaic (PV) modules and port III is connected to a dc link. The topology uses three single-phase full-bridge converters in the primary side and a three-phase full bridge converter in the secondary one. High-frequency isolation is realized by three single-phase transformers connected in open delta-wye configuration. The theoretical analysis is performed considering the fundamental component of the voltage across the transformers. Maximum power point tracking (MPPT), the battery current and power flow between the primary and secondary sides are controlled by the duty cycle variation of the primary-side switches and the phase shift variation between the primary and secondary bridges. In order to validate the study, computer simulations of the proposed system considering a 380-V dc link and rated power of 3.5 kW are carried out.