Analysis of DC-DC Converter with High Step-Down Ratio for Self-Extraction System of DC Distribution Network

A DC distribution network self-powering system needs to power electric equipment without relying on external AC power grids. However, this type of system faces challenges such as high-voltage DC input and low-rated voltage require-ments for the electrical equipment. To address the problems of switching device stress and cost caused by high input voltages, we have designed input series flyback converter with shared magnetic core. Compared with traditional single-ended flyback converters, this topology can effectively reduce the voltage stress on the switching devices and achieve high step-down ratios for high-voltage inputs and low-voltage outputs. This paper conducted principle analysis and parameter design for the converter, and finally developed a 200W high step-down ratio flyback converter with 1500V DC input and 24V output. The performance of the converter was verified through simulation using Matlab/Simulink.