Real-time frequency estimation of aircraft power source based on 3-line DFT

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.