基于磁路耦合的电力电子变压器直流变换技术

Improved DC Converter Based on Magnetic Coupling for Power Electronic Transformer

针对模块串联型电力电子变压器中变压器数量多、绝缘要求高的问题,设计了一种基于磁路耦合变压器的多有源桥直流变换器结构,能够提高模块化程度和减少高频变压器端口数目,提升系统功率密度。该变换器采用多磁芯高频变压器,变压器原边具有多绕组结构,对应多模块的串联,以满足输入高电压等级的要求;副边则采用单一绕组,对应全桥或多个全桥电路的并联,以承受副边较大的电流应力。改进的变换器在高压侧保持模块化结构,并且将变压器的磁芯和原边绕组集成到高压模块中,而低压侧使用统一的绕组和变换器,降低了高频变压器的设计难度。最后给出了该拓扑的等效模型和工作原理,并通过实验验证了所提变换器结构的可行性。

To overcome the problems in a series connected power electronic transformer such as a large number of transformers and higher insulation requirement,a multiple active bridge converter structure based on magnetic coupling transformer is designed in this paper,which can improve the modulation degree,reduce the number of ports of a highfrequency transformer,and enhance the system’power density.This converter adopts a multi-core high-frequency transformer.It has a multi-winding structure on the primary-side in response to the series-connection of multiple modules,thus satisfying the requirement of high-voltage level.On the secondary-side,it adopts a single winding in response to the full-bridge or the parallel connection of multiple full-bridge circuits,so as to withstand a higher current stress.The improved converter maintains a modular structure on the high-voltage side,in which the core of the transformer and primary winding are integrated.In contrast,it uses a uniform winding and converter on the low-voltage side,thus reducing the difficulty in designing the high-frequency transformer.The equivalent model of this topology and its operating principle are given.In addition,the feasibility of the proposed converter structure was verified by experimental results.