Isolated High Step-Up DC-DC Converter With Low Voltage Stress

WOS: 000332013100032Fuel cell stacks and photovoltaic panels generate rather low dc voltages and these voltages need to be boosted before converted to ac voltage. Therefore, high step-up ratio dc-dc converters are preferred in renewable energy systems. A new Z-source-based topology that can boost the input voltage to desired levels with low duty ratios is proposed in this paper. The topology utilizes coupled inductor. The leakage inductance energy can efficiently be discharged. Since the device stresses are low in this topology, low-voltage MOSFETs with small RDS (on) values can be selected to reduce the conduction loss. These features improve the converter efficiency. Also, the converter has a galvanic isolation between source and load. The operating principles and steady-state analysis of continuous and discontinuous conduction modes are discussed in detail. Finally, experimental results are given for a prototype converter that converts 25 V dc to 400 V dc at various power levels with over 90% efficiency to verify the effectiveness of the theoretical analysis.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [111E176]This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under the project contract 111E176. Recommended for publication by Associate Editor Y.-M. Chen