Floating high step-down stacked dc-dc converter based on buck-boost cells

In some high power dc-dc applications, where high voltage is present, a converter with high step-down ratio is required in order to provide an isolated low power auxiliary supply. This requirement represents a challenge and many topologies are currently being researched. The analysis of a non-isolated, unidirectional, high step-down voltage-ratio converter based on a stack of buck-boost converters is demonstrated. The converter is intended to be applied as a floating non-isolated power supply, which can be connected to one or more isolated converters. A design example is detailed and validated with simulations, and experimental results for a 200 W, 2.8 kV input voltage and 350 V output voltage converter.