Research On Low Power DC/DC Converter With High Frequency And High Efficiency

Distributed power system(DPS) consist of power generation system, primary electrical power supply and secondary electrical power supply. While the secondary electrical power supply provides power to electrical equipment directly, that is the module power supply that can be fixed to the PCB of this electrical equipment. As distributed power supply system is applied in the aerospace field, the module power supply is used more widely in the aerospace field, and request the module with smaller and high-efficiency.This thesis focuses on the domestic low power DC/DC module power supply, in which the fly-back topology or forward topology with resonant reset technology are applied, while the MOSFET is on the hard switching condition, resulting in the low efficiency and big size. On the one hand, with application of soft switch technology, the switching losses of high frequency greatly reduce; on the other hand, application of the synchronous rectification technology, the rectification losses greatly reduce, especially on the higher output current condition. We can make full use of the technology to improve the efficiency of the converter and reduce the power supply; it is good to realize the modularity of the switching power supply. This thesis is devoted to study the high-frequency and low power DC/DC module power supply, the study meet the development of module power supply, is of great significance for improving the repetitiveness of product.Firstly, after comparing of several different isolated DC/DC converters, Low-side active clamp forward converter has been selected to be the main circuit topology of the second power supply. And detail operation principle is presented.Secondly, the main circuit, control circuit and feedback circuit are designed, after introduces the concept of synchronous rectification, different types of synchronous rectification circuit are analyzed, give the dive solutions of synchronous rectification in the module power supply.Then, the simulation was built in the Saber according to the results of the various designed parameters to analyze and optimize the design.At last, the experimental results based on a 50 W power supply module with 18-36 V input, 5V/10 A output and the switching frequency of 300 k Hz are given to demonstrate the performance characteristics, the typical efficiency is over 90%. The prototype’s various property indexes meet the design demands.