A novel method to extract base-frequency of square wave from harmonics in spectrum

Harmonic component of square wave in spectrum is mostly responsible for electromagnetic interference (EMI). A novel method to extract base-frequency of square wave from harmonics, based on B-spline curve fitting method and histogram of frequency interval, is proposed, in which the obtained parameters can locate EMI sources and guide electromagnetic compatibility (EMC) design. Finally, experimental results in different situations are demonstrated, which show that the proposed method is feasible and improved.