摘要
三端口隔离DC-DC变换器(TAB)作为分布式光伏接入直流配电系统的一种积极探索与尝试,具有控制灵活性高及供电可靠性好的优势。传统移相控制方法下,当移相角发生突变时,各端口电感的高频链电流及高频变压器的励磁电流中存在暂态冲击和直流偏置现象,进而可引起开关管电流应力增加,导致变压器单向饱和,威胁变换器的安全运行。该文在量化TAB暂态直流偏置的基础上,从开关管驱动信号出发,剖析暂态直流偏置的形成机理,构建可抑制直流偏置分量的驱动信号数学模型,提出了两种典型的驱动信号组合方法。不同于占空比恒定的移相控制策略,该文通过改变各端口方波电压的占空比或加入与移相角相关的零电压阶段,进而可在一个开关周期内同时抑制各端口高频链电流及变压器励磁电流的直流偏置分量。通过模拟移相角跳变及输出功率突变,对比分析了传统移相控制策略与该文所提直流偏置抑制策略下各端口的响应特性。仿真及实验结果表明,该文所提方法不仅适用于移相角的多步阶跃跳变,在移相角连续变化的过程中也是有效的。
The application of three-port isolated DC/DC converter has been driven largely by the increasing demand for distributed photovoltaic in the field of DC distribution system.It has the advantages of high control flexibility and good power supply reliability.Due to the phase shift angle changes,conventional phase-shift control methods will cause transient impulse and DC bias in the high-frequency chain current of inductance and magnetizing current of the transformer,further increasing the current stress of switches and threating the safe operation of converter.Based on the quantification of the transient DC bias of TAB,the formation mechanism of transient DC bias is analyzed from the driving signals,and the mathematical model of DC bias suppression is constructed.Two typical driving signal methods are proposed.Different from the phase shift control strategy with constant duty cycle,the duty cycle is changed or the zero-voltage stage is added according to the change of phase shift angle.The DC bias of high-frequency chain current and transformer magnetizing current can be suppressed simultaneously in one switching period.The converter transient responses under the conventional phase shift control strategy and the proposed control strategy are compared and analyzed during the step change of phase shift angle and mutation of load power.The simulation and experimental results show that the proposed method is not only suitable for multi-step change of phase-shift angle,but also effective in the continuous change of phase-shift angle.
作者
余雪萍
涂春鸣
肖凡
刘贝
Yu Xueping;Tu Chunming;Xiao Fan;Liu Bei(National Electric Power Conversion and Control Engineering Technology Research Center Hunan University,Changsha 410082 China)
出处
《电工技术学报》
EI
CSCD
北大核心
2020年第9期1962-1972,共11页
Transactions of China Electrotechnical Society
基金
国家重点研发计划资助(2018YFB0904100).
