Characteristic Input Harmonics of DC-DC Converters and their Effect on Input Filter Design

Design curves are presented from which the individual harmonics generated at the input to a dc-dc chopper can be determined. The effect of the chopper output ripple current on the input harmonics is included. These generalized curves can be used to determine the input filter component ratings as well as to compute the harmonics injected into the source. Using harmonic superposition, the input current and voltage waveforms as a function of time are determined and thus the peak voltages and current stresses are obtained. A practical example illustrates the use of the curves and serves to verify the analysis.