Non linear inductor design for improving light load efficiency of boost PFC

With the increasing focus on energy efficiency and the enforcement of regulations such as IEC61000-3-2 that specifies the harmonic current limits in the line, power factor correctors (PFCs) are increasingly being used in power supplies. However, under light load conditions, the efficiency of various PFC topologies is poor. This paper illustrates a simple solution to improve light load efficiency through the use of a non linear inductor with a higher inductance at light load. The non linear inductor can be designed to satisfy efficiency requirements, or to get the best efficiency improvement with given size and cost constraint. In this paper, the analysis of losses in boost PFC circuit, the design of a non linear inductor with a given core characteristics for efficiency improvement, and experimental results are provided.