A Hybrid Modular DC/DC Converter for HVDC Applications

摘要

Recently, remarkable progress has been made in the voltage-source-converter-based high-voltage direct current (HVdc) transmissions. For the upcoming need to interconnect multiple dc transmission lines with different voltage levels, high-voltage and large power dcdc converters are necessary. This article investigates a nonisolated bidirectional dcdc converter that is composed by cascaded half-bridge submodules, series-connected diodes, and mechanical disconnectors. This hybrid topology presents very attractive features, such as low cost, high efficiency, and light weight. Operation principle, parameter design, and dedicated control strategies are developed. Simulation of a 150-MW, 200 kV300 kV dcdc converter has been performed to verify its performance and evaluate the efficiency. Moreover, a downscaled three-phase prototype rated at 500 V300 V 4.5 kW has been built and tested. The experimental results further confirm the effectiveness of the proposed dcdc converter.