Characteristic-Based Design of an LCC Resonant Converter With a Capacitive Filter

The
LCC
resonant converter with a capacitive output filter is a popular topology for variable load applications, although the simultaneous design requirements of wide load range, soft switching, and low conduction loss are not clearly tackled in available design strategies. In this article, the existing time-domain analysis of the converter is extended in a normalized design-oriented fashion. The proposed extension to boundary modes lends itself to the derivation of critical converter characteristics such as the soft switching range. A dimensionless converter and load characteristic-based design algorithm with parameter decoupling is developed to meet the load requirements. The design algorithm reduces the converter rms current while meeting practical requirements of zero-voltage switching and constraints on switching frequency across the load range. The proposed design method is validated using circuit simulations incorporating series dissipative nonidealities and the transformer magnetizing inductance, and also on a 160-W laboratory prototype with switching frequency within the designated limits and
$>96\%$
experimental efficiency.