Implementation of artificial frequency modulation in boundary mode power converters for EMI reduction

Reduction of EMI content of a power converter is a very important phase of the design of a commercial product. To do so, passive filtering can be used, but both the efficiency and volume constraints can be affected. Applying artificial frequency modulation techniques that spread the noise energy over a wider range of frequencies and, consequently, reducing the peak of the interfering signal is a proven approach for EMI reduction. These techniques are commonly implemented in fixed frequency converters, but the same benefits can also be achieved in variable frequency converters. This article describes the validation, implementation and verification of different techniques to obtain frequency modulation in boundary mode power converters.