中文摘要：

基于现代调制理论，首先对整流器和逆变器进行统一调制建模，通过分析其交直流侧的频率变换关系，揭示交流侧谐波、间谐波的产生过程。将谐波和间谐波的分析统一起来。并指出直流侧的纹波信号是变流器产生问谐波的直接原因。通过分析交直交变流系统两侧的交流信号在直流侧的互调产物，考虑两侧变流器之间的相互影响，针对不同的运行工况，特别是考虑系统三相不平衡、存在背景谐波等非理想情况下，详细推导各种情况下交直交变流系统的直流侧的纹波频率特征，利用交直流侧频率转换规则，很好地揭示交直交变流系统中的间谐波产生机理。仿真实验验证理论推导的正确性和有效性。

英文摘要：

Based on modern modulation theory, the uniform modulation model of rectifier and inverter was given, and through the deduction of the frequency transform rules between the AC and DC sides of the converter, the generation course of harmonic and interharmonic can be revealed, and the harmonic and interharmonic analysis can be unified. Considering the interaction between the AC signals of two sides in AC/DC/AC system, the intermodulation production in DC side was analyzed. The frequency trait of the ripple in DC side was deduced detailed under different conditions including ideal and nonideal conditions, utilize frequency transform rules the generation mechanism of interharmonic in the AC/DC/AC system can be analyzed elaborately. Finally, simulation experiments were presented, and the outcome proved the validity of the theory reasoning.