AC/DC变换器的谐波分析简化方法

以6脉波AC/DC变换器为例,采用调制理论法对其进行了谐波分析,针对变换器输入电压以及开关函数,分别对它们进行了序量分解以及序特性分析,并在此基础上利用三相序量乘积特性对变换器的谐波计算进行了有效简化。利用简化方法对变换器直流侧电压以及交流侧电流进行了谐波分析,并且与仿真结果进行比较,分析情况包括:电压无畸变、输入电压不平衡、电压畸变以及开关函数不平衡。结果表明当存在电压谐波畸变时会根据畸变次数不同产生不同次谐波电流,而当系统出现电源不对称或者开关不对称情况时,都会在其交流侧产生3、9、15等次谐波。该方法适用的范围广,简单易行,可推广到12脉波或更高脉波变换器中,但是对单相电路并不适用。

Simplified method of harmonic analysis for AC/DC converter

The modulation theory is introduced to the harmonic analysis for six-pulse AC/DC converter.Sequence decomposing and analysis are processed on its supply voltages and switching functions,based on which,the multiplication characteristics of three-phase sequence vectors are used to simplify the harmonic analysis of converter.Harmonic analysis is performed for the DC voltage and AC current of converter,and the result is compared with that of simulation for different conditions:voltage without distortion,unbalanced supply voltage,voltage distortion and asymmetric switching function.When there are voltage distortions of different orders,harmonic currents of different orders are generated accordingly.When there are unbalanced supply voltages or asymmetric switching functions,harmonics of 3rd,9th,15th,etc.will arise at AC side.Being simple and practical,this method can be applied to 12-pulse and above converters, but is inapplicable to single-phase circuit.