A High-Efficiency Isolated-Type Three-Port Bidirectional DC/DC Converter for Photovoltaic Systems

Abstract

This paper proposes a novel high-efficiency isolated three-port bidirectional DC/DC device for photovoltaic (PV) systems. The device contains a high step-up converter for PV modules to supply power to the DC bus, and a bidirectional charge/discharge control circuit for the battery with an improved boost-flyback converter. When the PV modules supply sufficient energy, their output can be stepped up and energy supply to the DC bus and charging of the battery can be achieved simultaneously. However, when the energy supplied is insufficient, the battery provides energy to the DC bus. When the proposed converter is operated in the step-down mode, the DC-blocking capacitor on the high-voltage side is used to reduce the voltage on the transformer and achieve high step-down performance. Moreover, to improve the overall efficiency of the system, the energy stored in the leakage inductance is recycled and supplied to the DC-blocking capacitor during operation in the step-up mode. Finally, to verify the feasibility and practicability of the proposed devices, a 500 W three-port bidirectional DC/DC devices was implemented. The highest efficiencies achieved for operation in different modes were as follows: high step-up mode for the PV modules, 95.2%; battery step-up mode, 94.2%; and step-down mode, 97.6%.

A Multifunctional Isolated and Non-Isolated Dual Mode Converter for Renewable Energy Conversion Applications

“…The converter had relatively low efficiency at the high-conversion-ratio isolated modes due to the reduction of the entire efficiency when the converter works in cases of high ratio, which uses twostage circuits in series. Table 3 presents a comparison between the proposed converter with another related bidirectional non-isolated converter studied in [47] and the isolated converter described in [48]. The proposed converter in this paper had better features including diversified operation modes, adjustable electrical isolation non-isolation, and wider voltage conversion ratios.…”

“…Table 3 presents a comparison between the proposed converter with another related bidirectional non-isolated converter studied in [47] and the isolated converter described in [48]. The proposed converter in this paper had better features including diversified operation modes, adjustable electrical isolation non-isolation, and wider voltage conversion ratios.…”

A Nonisolated Three-Port DC–DC Converter with Continuous Input and Output Currents Based on Cuk Topology for PV/Fuel Cell Applications

“…The isolated TPC uses a transformer with a high-frequency nonisolated converter topologies. The isolated TPC uses a transformer with a high-frequency to provide magnetic coupling and electrical isolation between the source and load [6][7][8]; partially isolated converters use a common DC bus along with magnetic coupling [9]. A nonisolated TPC uses common DC bus and finds applications where the isolation is not needed between the ports [10][11][12].…”

Slope Compensation Design for a Peak Current-Mode Controlled Boost-Flyback Converter

“…High step-up power converters are some of the main devices used in photovoltaic applications [15][16][17][18][19] due to the low output voltage of solar panels. With such applications, efficiency is a key issue, so single-stage converters are preferred over more complex converters [17,18].…”