Investigation of EMI reduction in buck converter by using external chaos generator

DC-DC converters widely employed in various electrical and electronic appliances, release electromagnetic emissions and thus form prominent sources of Electromagnetic interference due to their inherent fast switching. By operating the converters in chaotic mode EMI can be reduced without adding any filters. In this paper, voltage controlled buck converter is analyzed by FFT for EMI reduction under chaotic mode operation is proposed. The chaos is induced externally into the buck converter by using Wien bridge oscillator as its exhibits various forms of chaotic behaviour when operated in oscillatory mode. Simulations are performed using PSpice for observing chaos for the variation of input voltage. EMI reduction is observed for both conventional model of buck converter operating in chaotic mode for certain voltage range and proposed model of buck converter using FFT by spreading the spectra of the output signals over the whole frequency band. A protype model has been tested and hardware results shows the significant reduction of EMI in chaotic mode operation of buck converter.