基于三线DFT的航空电源频率实时检测算法

摘要

针对航空变频电源的频率（360～800Hz）检测,提出了一种基于三线离散傅里叶变换（DFT）的实时检测算法。首先对采样序列加汉宁窗,通过DFT计算基波频率主瓣区域的离散谱线幅值,推导出基波频率与3条离散谱线幅值的数值关系。其次结合电力系统的基波和谐波特点,分析了该算法无主瓣频谱泄露的采样点数选择方法;采用旋转坐标法计算离散谱线幅值,使三线DFT计算量得以显著减小;通过迭代法估计频率初值,对航空电源宽范围连续变化值进行检测,克服栅栏效应。仿真和实验结果表明,该算法具有良好的实时性,阶跃响应好,稳态精度高。%A real-time frequency estimation algorithm based on 3-line discrete Fourier transform(DFT) is presented in this article for variable frequency measurement in aircraft power system.The signal is firstly weighed by means of Hanning window,and the spectrum amplitude in main lobe area is calculated via DFT.The numerical value relation between fundamental frequency and 3-spectrum amplitude is then derived.According to the features of power system,the number of samples in the algorithm is determined,which has no main lobe spectrum leakage.The spectrum amplitude is extracted in rotating reference frame to effectively reduce the computation effort.Iterative calculation of initial frequency is introduced to perform continuously long-range frequency estimation with no fence effect.Simulation and experimental results show that the proposed technique can simultaneously track the frequency with fast step response and high steady-state accuracy.