几种FFT加窗三次样条插值的间谐波检测方法的比较

Comparison of several interharmonics detection approaches based on windowed cubic spline interpolation FFT

在非整周期采样的情况下,快速傅里叶变换(fast Fourier transform,FFT)存在较大的误差。文章通过在Matlab中对构造的信号模型进行仿真,比较了几种基于三次样条插值的加窗FFT算法的间谐波检测精度,并以Blackman-Harris窗三次样条插值FFT算法为例,对其进行了公式推导,得到了该算法信号频率、幅值和相位的计算公式。仿真结果表明,文中的几种基于三次样条插值的加窗FFT算法的间谐波检测精度较高,频率平均误差可达到0.02%以内,幅值平均误差可达到0.3%以内,有效地减小了非整周期采样对FFT的影响。

In the case of non-integer-period sampling, there is a big error in fast Fourier transform （FFT）. In this paper, the precision of several interharmonics detection approaches based on win- dowed cubic spline interpolation FFT is compared through the simulation of signal model in Matlab. Taking Blackman-Harris window cubic spline interpolation FFT algorithm as an example, the formula derivation of the algorithm is done to get the computational formulas of frequency, amplitude and phase. The simulation results show that the precision of several interharmonics detection approaches based on windowed cubic spline interpolation FFT in the paper is high. The average error of frequency can be lower than 0.02 %, and the average error of amplitude can be lower than 0. 3%, thus reducing the influence of non-integer-period sampling on FFT effectively.