Multiple-Input Soft-Switching DC-DC Converter to Connect Renewable Energy Sources in a DC Microgrid

This paper presents a new multiple-input soft-switching DC-DC Cuk converter for clean and renewable energy sources. The proposed converter can buck and boost the different voltages of renewable energy sources to produce a constant DC output voltage in a DC microgrid. In the proposed converter, edge-resonant soft-switching modules are used to perform better than the conventional multiple-input Cuk converter. All switches in the edge-resonant soft-switching modules can realize zero-current switching turn-on and zero-voltage switching turn-off. By using these modules, the proposed converter can achieve lower current stress of the switches, wider soft-switching range, and higher power efficiency than the conventional multiple-input Cuk converter. These advantages are achieved in the edge-resonant modules, which optimize soft-switching states and costs. In addition, the soft-switching states can be easily achieved because the edge-resonant soft-switching modules have a wide soft-switching range. Furthermore, the proposed converter can independently transfer the generated power from renewable energy sources to the DC microgrid. In this article, the operation principles and performance of the proposed converter are discussed in detail. The theoretical analysis is validated by experimental results obtained from a laboratory-scale prototype and full-scale real-time hardware-in-the-loop experiments.