基于环流提取法的近似零电流换相低谐波双反星形整流器

Approximate zero-current commutation and low-harmonic double-star rectifier with circulating current extraction

变压器的漏感使得整流器的换相不能瞬时完成,在低压大电流场合会对整流器的输入输出特性产生较严重的影响。给出了能有效抑制输入电流谐波并消除换相压降时所需提取的直流侧环流类型,在此基础上分析了直流侧环流对换相过程的改善机理,发现了提取的环流产生的二次换相,建立了二次换相模式下,整流器的换相重叠角、换相压降及输入电流谐波与电路参数之间的关系表达式,分析结果表明提取的直流侧环流不仅能显著减小输入电流谐波和换相重叠角,而且使整流器工作于近似零电流换相状态,得到了一种近似零电流换相的低谐波整流器。研制了一台额定功率为1.1 kW的实验系统,实验结果验证了理论分析的正确性及其在大电流场合的应用价值。

The current commutation of rectifier cannot be instantly completed due to the leakage inductances of transformer,which may seriously influence its input/output performance in low-voltage and big-current applications. The type of circulating current required to effectively reduce the input current harmonic and eliminate the output voltage drop is given,based on which,the mechanism of current commutation improvement by circulating current is analyzed,the second commutation induced by the extracted circulating current is found,and the expressions of relationship between the overlap angle,output voltage drop or input current harmonic and the circuit parameters in the mode of second commutation are established. Theoretical analysis shows that,the extracted DC-side circulating current can not only significantly reduce the input current harmonic and commutation overlap angle,but also make the rectifier operating in an approximate zero-current commutation condition. An approximate zero-current commutation and low-harmonic double star rectifier is obtained. A 1.1 kW experimental system is designed and the experimental results validate the correctness of theoretical analysis and the application prospect of the designed rectifier in large current condition.