A Double Uneven Power Converter-Based DC-DC Converter for High-Power DC Grid Systems

This paper presents a novel double uneven power converter-based dc-dc converter and its design and control methods. The main objectives are to reduce the power losses in the power semiconductor devices and to reduce the output filter inductance in a high-power (megawatt-level) dc-dc converter. The proposed converter utilizes two full-bridge converters in a special way to realize zero-current switching and to reduce the output filter inductance. The advantages of the proposed converter become more significant for high-power applications. A comparative simulation for a dc-grid wind farm application has been performed to verify the effectiveness of the proposed converter in high-power applications. It has been shown that the proposed converter not only requires less filter inductance but also has less power losses in the semiconductor devices. A small-scale prototype has been built to verify the operational principle of the proposed converter.