谐波滤除器Harmonic filter 谐波和无功的产生和危害 Occurrence and harm of harmonics and reactive power 现代工业和家电业的技术发展，使得电力电子设备被广泛使用，电力电子设备中大量使用了半导体开关器件， 这些器件只允许电流在整个周期的某一部分导通，从而使用户端电网侧电流不连续，造成电流波形的失真。另外对于三相四线制系统，如果三相负荷不平衡，会造成三相电流的不对称。 Nowadays the power and electronic equipment are widely used, these equipments adopted many semi-conductive components, which allow some section of a full current wave only, and result in discontinuous current, namely current distortion. Also for the 3-phase 4-wire system, if the three-phase load is unbalanced, it will lead to asymmetrical current. 根据傅里叶 (Fourier) 定理，任何周期函数可以分解为一个直流量和一系列正弦量 (频率为 原始周期函数频率的整数倍) 的和，频率等于是原始周期函数的正弦量称为基波，频率等于基波频率“n”倍的正弦量波形称为“n”次谐波。可见纯正弦化的电流波形不含谐波电流成分，而前述的失真的电流波形则含有谐波电流成分。 According to Fourier theorem, any periodical function can be decomposed as DC content and the sum of series of sinusoidal contents (its freq is integer multiple of original periodical function), the sinusoidal wave with freq same as original periodical function is basic wave, “n” times of the freq of basic wave is N power harmonic, consequently pure sinusoidal current wave does not contain harmonics, distorted current has harmonic contents. 下图为典型变频器的输入侧电流波形及傅里 The following figure is a typical case current wave of input side in inverter and Fourier 未滤波的线电源%基波值 Basic wave value of unfiltered line power source 未滤波的线电源 Unfiltered line power source 一般通过波形的“总谐波畸变率简称THD) ”来定义波形的失真程度和谐波含量： Generally total harmonic distortion rate (abbreviation: ...
