摘要
相较于隔离型电力电子变压器(PET),非隔离电力电子变压器(NI-PET)取消了中间级隔离DC-DC变换器,具有功率密度高、变换级数少的优点。但该拓扑存在的直流电容短路路径限制了其应用领域且对可用开关状态和矢量边界产生的影响尚不明确。因此,该文首先分析单相-单相NI-PET矢量边界与调制度、前后级相位差的关系;其次结合贯通牵引供电系统需求,提出一种适配既有牵引变压器的两相-单相非隔离电力电子变压器,并提出一种规避所提拓扑短路矢量的三维空间矢量脉宽调制(3D-SVPWM)策略;最后结合Vv牵引变压器仿真和实验验证了所提拓扑应用于牵引供电系统的可行性,以及所提调制策略规避短路路径的有效性。结果表明,所提拓扑在保证系统输入输出特性良好的基础上,彻底取消隔离环节,降低了牵引供电系统成本。
Electrical isolation in advanced power supply systems typically relies on power frequency transformers or high-frequency isolation DC-DC converters.However,the transformers result in multiple converter stages and increase the system’s complexity and cost.To reduce the cost of advanced traction power supply system,this paper proposes a two-phase to single-phase non-isolated power electronic transformer(NI-PET)topology based on the existing traction transformer and has the advantages of fewer transformation stages and higher system efficiency.Some switch states can result in short-circuit paths of the DC-link capacitance in NI-PET topology.The traditional modulation strategy fails to avoid the short-circuit paths.A three-dimensional space-vector pulse width modulation(3D-SVPWM)strategy is proposed based on the 3D space vector distribution diagram,taking the vectors of three ports as the coordinate axis.According to the number of available vectors,the 3D space is divided into different ranges.In addition,the proposed strategy determines the range of reference voltage vectors and selects available space vectors to complex the demanded reference vector.Finally,based on the V-v traction transformer,the simulation model and experimental platform are built.Simulation and experimental results show that compared to the traditional space pulse width modulation(SPWM)strategy,the proposed modulation strategy can realize the stable operation of the system.When the load and grid-side voltage fluctuate repeatedly in a short period,the two-phase to single-phase NI-PET system restores a steady state within 0.2 s,the grid-side power factor remains above 0.99,and the THD of input and output current is less than 3%.With the same load,the three-phase current unbalance degree of the proposed topology is about 45%less than the traditional power supply system.It is verified that the proposed topology and modulation can adapt to harsh conditions such as continuous load and grid-side voltage fluctuations.Compared to PET,NI-PET avoids the loss caused by the isolation stage,thus significantly improving the efficiency.In the low-power experimental platform,the efficiency of NI-PET is about 10%higher than PET.The following conclusions can be drawn.(1)The proposed two-phase to single-phase NI-PET topology can adapt to the harsh conditions of advanced traction power supply systems.It has the advantages of low cost and good power quality.(2)Compared to the traditional modulation strategy,the proposed one can avoid the short-circuit paths of DC-link capacitance.There is no short-circuit current that is much larger than the load current on the cascade line.(3)The proposed topology can achieve about 10%efficiency improvement in a low-power experimental platform and is expected to increase the efficiency by about 2%in industrial PET.
作者
王悦
孟令辉
吕霄
徐寄望
舒泽亮
Wang Yue;Meng Linghui;LüXiao;Xu Jiwang;Shu Zeliang(School of Electrical Engineering Southwest Jiaotong University,Chengdu 610031 China;Sichuan Aerospace Fenghuo Servo Control Technology Corporation,Chengdu 611130 China)
出处
《电工技术学报》
北大核心
2025年第8期2547-2559,共13页
Transactions of China Electrotechnical Society
基金
国家重点研发计划(2021YFB2601500)
国家自然科学基金(52077183)资助项目。
关键词
非隔离电力电子变压器
两相-单相
规避短路矢量
三维空间矢量脉宽调制策略
Non-isolated power electronic transformer
two-phase to single-phase
avoiding short-circuit vectors
three-dimensional space vector pulse width modulation(3D-SVPWM)strategy
