High-Power Multilevel Step-Up DC/DC Converter for Offshore Wind Energy Systems

This paper presents a multilevel step-up DC/DC converter for DC grid-based offshore wind energy conversion applications. The main features of the proposed multilevel converter are as follows: 1) the voltage stress of the power devices can be lowered, making it suitable for high-voltage applications; 2) the boost inductor can be significantly reduced which leads to the outstanding dynamic performance; and 3) it can reach a high-voltage gain, which is well suited for high-gain applications. The theoretical analysis is carried out for a four-level step-up converter. Therefore, the converter can be extended to any arbitrary number of levels. The proposed four-level converter is verified by a simulation and evaluated to the conventional multilevel DC/DC converter in terms of component stress and power device count. The developed topology has been implemented on a 2-kW prototype converter to confirm its feasibility.