Random Modulation Schemes for Conducted-EMI Mitigation on Sepic Converter

摘要

This paper proposes new random modulation schemes to mitigate conducted Electromagnetic Interference (EMI) in Single-ended Primary-inductor converter (SEPIC). The effectiveness of randomization on spreading the dominating frequency was studied by carrying out simulations using the MATLAB software and by estimating output power spectral density (PSD). Furthermore, the effect of using the proposed randomization techniques on conducted- EMI characteristics of the SEPIC converter is simulated and experimentally investigated. A comparative study has been carried-out to understand the effect of proposed schemes on PSD and conducted-EMI mitigation. Experimental results confirm the validity of the estimated and simulation results, and demonstrate the effectiveness of applying the randomization schemes in reducing the conducted-EMI. The class- B International special committee on Radio Interference (CISPR 22) standard has been adopted for measurements. Both simulated and measured results agree well, based on which Constant Trailing Edge, Randomized Duty ratio and Randomized Pulse Position Modulation with Fixed Carrier Frequency (CTERDRPPMFCF) scheme was contemplated for adoption.