请问谐波测试设备的测试原理是什么？

terrycjb

  据个人愚见，谐波测试要想得到基波的谐波电流，只能有两种方法：1）采用硬件方法，即对每次谐波设计一个带通滤波器，虑除（衰减掉）其他（测试）不需要频率的电流波形，从而获得相应的谐波电流；2）就是通过FFT（即快速傅立叶变换）来进行数学处理，这需要将基波周期之内的全部电流波形采样后就行傅立叶数学分析后计算除各次谐波电流。不知道实际使用方法到底是什么？？请大侠告知，谢谢！

sysop

这个也很easy，去看一下DFT、FFT的原理就知道了（本科时就该学过的课程）。
1。指定T（周期）；
2。采样系统，自动以最大的T作为周期。

chess_yen

电源产生谐波的主要原因，一是开关电源中普遍采用电容滤波型桥式整流电路，造成输入电流波形畸变；二是电源电路中的开关器件（二极管、三极管）及感性负载工作于高频开关状态而产生尖峰脉冲。

kopro

Total Harmonic Distortion (THD) Analyzers ...calculate the total distortion introduced by all the harmonics of the fundamental frequency wave. In most cases THD is the amount that is required to calculate, rather than distortion caused by individual harmonics. This type of analysis is very important in systems (e.g. Audio) in which filters having an extremely small passband/ stopband is desired, such as a notch filter.

The applied input wave is impedance matched with the rejection circuit with the help of an attenuator and an impedance matcher. This signal is then applied to a pre-amplifier which raises the signal level to a desired value. The following section consists of a Wien bridge. The bridge is tuned to the fundamental frequency by frequency control and it is balanced for zero output by adjusting the bridge controls, thus giving a notch in the frequency response of the rejection section. After the Wien Bridge, a bridge amplifier follows that simply amplifies low harmonic voltage levels to measurable higher levels. A feedback loop is formed from Bridge Amp o/p to the Pre-Amp i/p thus eliminating even the slightest effect of fundamental frequency. This filtered output is then applied to a meter amplifier which can be an instrumentation amplifier. This amp raises the voltage levels to the compatibility of the meter scale/digital meter which follows. Thus the total voltage obtained at the meter output shows the amount of distortion present in the wave due to harmonics of fundamental.

foxwolf

是不是用滤波的方法呀

curoky

什么是谐波，为什么C类产品第二次有限值，然后就一直是奇次有限值，偶次没有？ [s:15]  很想知道，求各位大侠帮忙解答下啊 [s:28]