Two-Stage Hybrid Isolated DC-DC Boost Converter for High Power and Wide Input Voltage Range Applications

A two-stage hybrid isolated dc-dc boost converter for high power and wide input voltage range applications is proposed. It can be used as a front-end dc-dc converter that can boost variable low voltage from a power source [battery (home/industrial inverter/industrial UPS application), fuel-cell or solar-PV] and interface it to a high-voltage dc-ink, which typically feeds an inverter. A detailed comparison among the different family of converter topologies for isolated dc-dc boost application is carried out that can prove to be useful for power electronics engineers to choose the correct topology for a given input voltage range. The quantitative comparison takes into account the power device utilization, transformer utilization, capacitance utilization, and inductive energy requirement. Based on the comparison, it is shown that with input voltage variation greater than +/- 20%, two-stage hybrid isolated dc-dc boost converter is superior compared to other family of converters. Design details for the two-stage converter are provided. The converter is developed and tested for a 5 KW inverter application with an input dc voltage range of 90-170 V and output ac voltage of 230 V. Theoretical analysis for loss calculations is also provided which closely matches the experimental results.