Battery Integrated Three-Port Soft-Switched DC-DC PSFB Converter for SPV Applications

This paper proposes a three-port soft-switched DC-DC converter integrating solar photovoltaic (SPV) source, battery energy storage system (BESS), and DC load. The proposed converter modifies the basic phase-shifted full bridge (PSFB) DC-DC converter topology with the addition of a link inductor to create a three-port converter structure and it uses a secondary passive clamp circuit to minimize the unwanted circulating current loss suffered by the conventional PSFB converters. The load port is isolated from the SPV and BESS port through a high frequency transformer. All semiconductor switches and diodes of the converter change their switching states under soft conditions. The proposed converter uses closed loop controller for maximum photovoltaic power extraction, charge/discharge control of BESS and load voltage regulation. Detailed steady-state operation of the converter with design guidelines of power and control circuits are presented in this work. Finally, real-time performance of the converter under different solar irradiance and load conditions is successfully validated through laboratory testing of a hardware prototype.