一种双向谐振型高频直流变压器通用参数设计方法

交流微电网和直流微电网之间多通过电力电子变压器(PET)构成交直流混合微电网以减少额外的电能转换环节。但是PET中高频变压器的谐振参数常常限值了效率的提升,且谐振拓扑的细微变化也会进一步加剧参数设计的难度。针对该问题,提出一种面向交直流混合微电网(HADM)的双向谐振型高频直流变压器(HFT)通用型参数设计方法,明确只有在谐振电流与输入方波电压基频部分同频同相时传输的平均功率最高。并指出当变压器励磁电感与漏感之比大于一定值时,CLLC、LLC和CLL谐振型高频变压器均可工作在双向功率传输状态,且获得的标幺化增益和效率均满足HADM系统要求,CLLC更有利于功率的有效传输。最后,搭建了一台采用SiC器件的6 kW实验样机,实验结果进一步验证了所提设计方法的可行性和有效性。该样机在双向工作模式下的最高效率大于97%。

A generalized parameter design approach for bidirectional resonant high frequency DC transformers

DC micro-grids and AC micro-grids are usually connected with a Power Electronic Transformer(PET)to operate as a Hybrid AC/DC Micro-grid(HADM)and reduce energy conversion.However,the resonant parameters of a High Frequency Transformer(HFT)limit the efficiency of a PET,and a slight variation of the topology poses a big challenge on parameter design.Therefore,a generalized parameter design approach is proposed for a bidirectional high frequency DC transformer.It is derived that the maximum transmission power of an HFT is ensured by keeping the resonant current in phase with the fundamental part of the input voltage.Meanwhile,the resonant HFT with CLLC,LLC or CLL will successfully transmit power bi-directionally and satisfy the requirement of normalized gain and efficiency of an HADM system,when the ratio between the magmatic inductance and the leakage inductance is larger than a certain value.The CLLC topology is conducive to the power transmission.Finally,a 6 kW experimental prototype with SiC is established to verify the feasibility and effectiveness of the proposed approach.The maximum efficiency is more than 97%in the bidirectional operating mode.