Real-time identification of multi-component periodic signals using Online Harmonics Extraction Approach

To identify the frequency and amplitude of a periodic signal in real-time, a novel approach termed the "Online Harmonics Extraction Approach (OHEA)" is proposed in this paper. This method employs a notch filter with an adjustable center frequency to identify the frequency of periodic signals accurately. The computation of the envelope curve and phase-sensitive detection are combined to identify the signal amplitude and smooth out transient stages. By applying the extremum-seeking method, the identified results are fed back to adjust the center frequency, forming a closed-loop system. The convergence of the identification process is analyzed qualitatively, and a parallelized multi-component structure is proposed. Simulations and experimental results on a disturbance identification system verify the effectiveness and superiority of OHEA in the real-time identification of time-varying frequency and amplitude.