Optimal design of air-core inductor for medium/high power DC-DC converters

Inductors are one of the largest and heaviest components of the DC-DC converter in medium/high power applications. As volume/weight of the converter becomes more important, high frequency is considered in the design of the converter and inductors with low inductance and high currents are required. Air-core inductors can be considered as good alternative, since they are not subject to saturation problems and may provide a reduction on total weight and losses of the converter if an appropriated design is performed. This paper presents an analysis of air-core inductors for DC/DC converters. First, a simplified inductor design is proposed to optimize the power losses by using litz wire winding. Then, results from the proposed design methology are compared with commercial iron-core inductors byusing metaparameterisation approach. A comparative analysis is performed between commercial iron-core inductors and air-core inductors regarding power losses, volume and weight for a bidirectional DC-DC converter. Because the number of parameter that influence the selection of the inductance in a DC-DC converter, then the comparison is done by use desicion chart, which help to define when a type of inductor is better than the other. Air-core inductor will left more benefit for power rating higher than 1MW.