CAJ | 학술논문

提出了一种基于LLC谐振变换器的三级型降压式电力电子变压器(PET)拓扑结构。所述结构的输入侧高压级为二极管钳位三电平整流电路，以降低开关器件耐压等级；隔离级采用了三电平LLC串联谐振型DC/DC变换器，其每个主开关电压应力是输入电压的一半，并且在全负载范围内工作在软开关状态，可降低PET的损耗，提高其效率；输出侧低压级为两电平三相四桥臂逆变电路，以应对大量存在的不平衡和非线性负载。对所述的 PET 结构进行了控制方案设计，并做了仿真研究。仿真结果表明：该PET结构在实现了传统变压器隔离、变压和能量传递等功能的基础上，还具备电能质量调节功能，可有效避免系统与负载之间因不平衡或畸变而对彼此产生的影响。
제출료일충기우LLC해진변환기적삼급형강압식전력전자변압기(PET)탁복결구。소술결구적수입측고압급위이겁관겸위삼전평정류전로，이강저개관기건내압등급；격리급채용료삼전평LLC천련해진형DC/DC변환기，기매개주개관전압응력시수입전압적일반，병차재전부재범위내공작재연개관상태，가강저PET적손모，제고기효솔；수출측저압급위량전평삼상사교비역변전로，이응대대량존재적불평형화비선성부재。대소술적 PET 결구진행료공제방안설계，병주료방진연구。방진결과표명：해PET결구재실현료전통변압기격리、변압화능량전체등공능적기출상，환구비전능질량조절공능，가유효피면계통여부재지간인불평형혹기변이대피차산생적영향。
A three-stage buck power electronic transformer (PET) topology based on the LLC resonant converter is proposed. In the proposed PET,the high voltage stage on the input side is a diode-clamped three-level rectifier for use in reducing the voltage withstanding grade of switching devices.The isolation stage adopts a three-level LLC series resonant DC-DC converter, the voltage stress of each of whose main switches is half the input voltage.It can realize soft-switching from no-load to full load,which will reduce losses and improve efficiency.The low voltage stage on the output side is a two-level three-phase four-leg inverter to cope with the huge imbalance and nonlinear loads.A control scheme is designed and simulation is performed to verify the performance of the proposed PET.Simulation results show that the proposed PET not only has the basic features of isolation,voltage transformation and energy transmission as does the traditional transformer,but also carries out the power quality regulating function,which can avoid the mutual influence between system and load due to imbalance and distortion.