A Pareto-Optimized, Capacitively Isolated SEPIC Converter for Wide Load Ranges and High Frequency Power Conversion

This paper presents a resonant, capacitively isolated single-ended primary-inductor converter (SEPIC) suitable for high frequency power conversion operating at 10 MHz. Instead of an extensive manual parameter sweeping, parametric loss models are used to perform a Pareto optimization of the converter design. It is shown that this design approach is highly beneficial. The converters high efficiency of 90 % and its wide voltage range sets it apart from similar designs. It achieves voltage conversion ratios from zero (buck) to eight (boost) and throughout most of this range the converter can maintain soft switching conditions. The concept demonstrates that at such high frequencies a galvanic isolation can simply be implemented with capacitors instead of a transformer. Within the analysis, two circuit board prototypes with different technologies, FR4 and insulated metal substrate, are compared with respect to their electrical and thermal performance.