Exploiting the Benefits of Partially Saturating Inductors on Switch-mode Power Supplies Electro-magnetic Compatibility and Efficiency

This paper discusses - through experiments and simulations - the benefits of Partially Saturating Inductors (PSIs) in reducing the conducted Electro-Magnetic Interference (EMI) and increasing the efficiency of Switch-Mode Power Supplies (SMPSs) under Light Load Operation (LLO). The manifold SMPSs operation characteristics, power devices, control techniques, and design arrangements influencing conducted EMI have stimulated in the last decades the development of several EMI mitigation techniques, which allow facilitating compliance with Electro-Magnetic Compatibility (EMC) standards. The introduction of new integrated control techniques for the efficiency improvement under LLO and the possibility, now better understood, to use PSIs to reduce size and weight of SMPSs, make today the joined EMI and efficiency analysis particularly challenging. This paper shows that using PSIs helps achieving a good tradeoff between EMI and efficiency in an SMPS under LLO. The paper discusses practical examples regarding modeling, simulation and experimental testing of low-power non-isolated DC-DC power converters using PSIs under LLO.