基于容性能量转移原理的高压大容量DC/DC变换器

随着基于电压源型换流器的柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)技术的快速发展,十几年间世界范围内已建成数十个各种不同电压等级的VSC-HVDC工程。根据交流电网的发展历史,未来构建大规模直流电网是必然趋势。然而直流电网必须采用DC/DC变换器来充当直流变压器的角色,因此高效率、低成本的高压大容量DC/DC变换器是直流电网技术中亟待攻克的关键基础性课题。该文针对不同电压等级直流输电线路互联的技术需求,对经典低压DC/DC拓扑进行改造,推演出一系列基于容性能量转移原理的高压大容量DC/DC变换器拓扑,并揭示此类拓扑的演化规律和换流原理。相比传统变换器方案,该拓扑可降低器件数量,提升拓扑转换效率以及减小变换器体积重量。最后,通过仿真和实验验证基于容性能量转移原理的DC/DC变换器的可行性。

Capacitive Energy Transfer Principle Based High-voltage High-power DC/DC Converters

With the rapid development of voltage source converter based high voltage direct current(VSC-HVDC) transmission, dozens of VSC-HVDC projects with different voltage ratings have been built worldwide during the last decade. According to the development history of AC grids, it is an irresistible trend to develop large-scale HVDC grids. However, DC/DC converters must be utilized to act as DC transformers in HVDC grids. Therefore, highly efficient and low-cost high-voltage high-power DC/DC converter is currently one of the key fundamental techniques needed by the HVDC grids. In order to satisfy the technical requirements of interconnecting HVDC lines with different voltage ratings, this paper developed a series of capacitive energy transfer(CET) principle based DC/DC topologies by modifying the classic low-voltage DC/DC converters. The topology evolution rules and current commutation mechanism were presented. Compared to conventional DC/DC converter topologies, the CET topologies were able to reduce the component count, improve conversion efficiency, and reduce the weight and size of the converter. At last, simulation and experimental results validated the effectiveness of the CET principle based DC/DC converter.