A Novel Transformerless Common-Ground AC/DC Switching Converter with Integral Fault Protection utilizing Active Isolation Techniques

This paper presents a novel transformerless common-ground AC/DC switching converter with integral fault protection utilizing Active Isolation (AI) techniques. The power converter employs a standard buck-boost topology but isolates the converter by the addition of lateral active switch devices on the low-side power path. Compared to transformer isolation, this active isolated converter has reduced size and cost with increased efficiency. The paper includes a detailed discussion of circuit operating principles, modeling, fault detection, and experimental results. A 300W, $120 V_{ac}-to-19 V_{dc}$ converter is prototyped and experimental measurements are correlated to calculated results. The proposed fault protection solution is found to properly protect the converter in the event of a switch short failure on and switch device.