The Design and Analysis of a Capacitively-Isolated Series-Parallel Converter

Series-input, parallel-output power converters are an effective solution for applications requiring high power density and large conversion ratios. Hybrid switched-capacitor topologies are a compelling alternative to the traditional magnetics-based topologies commonly used in stacked converters. One required feature of these series-input, parallel-output converters is the ability to achieve electrical isolation between the input and output grounds. Capacitor-based isolation enables low passive volume, indicating the potential for use in weight-and volume-constrained application spaces. This work presents a capacitively-isolated variant of the series-parallel hybrid switched-capacitor converter capable of at-and above-resonance operation. Analysis and operation for symmetric and asymmetric variants of the capacitively-isolated series-parallel converters are presented. The converters presented in this work are compared to existing capacitively-isolated hybrid switched-capacitor converters via passive volume and switch stress analysis. Experimental results of a prototype of the 4:1 capacitively-isolated series-parallel converter validate the analysis.