Development Of A 28V Input 50W Output DC/DC Module

With the development of technology,smaller size and lower power loss have become the developing trends for the electronic instruments.So,the technology of power supply should keep developing towards higher integration and higher efficiency.Improving power density has always been a hot issue in research field and it is of great significance to develop a high power density DC/DC module with high performance.To develop a wide-temperature operation(-45-105?),50 W output,high-power-density DC/DC module,this paper focuses on the improvements of efficiency and dynamic response as well as the increase of operation frequency.First,the active-clamp-forward converter is adopted,the multi-layer structure with aluminum substrate is designed,and a planar transformer is developed to reduce the volume of the DC/DC module.Then,the first round prototype is fabricated and tested,while with a efficiency not high enough and poor dynamic response.In order to solve the problems above,the efficiency and the dynamic response of the DC/DC module are improved through loss analysis and loop characteristics analysis.Firstly,based on the overall loss analysis,the planar transformer is selected as the object of loss optimization.Secondaly,the number of turns and the winding distribution of the planar transformer are optimized for lowing copper loss,and the optimization results of the efficiency characteristics are verified by the theoretical analysis,the Maxwell simulation and the experiments.And then,the influences of the power stage,magnetic reset stage and control stage circuit parameters on the loop characteristics are analyzed,and the comparison between transient time domain waveform and frequency domain index is carried out.Finally,the optimization design of the loop parameters is given.As a result,the shutdown problem is solvedAnd the dynamic response is improvedIn addition,to increase the power density further,the switching frequency is increased from 300 to 800 kHz,and the Si device is replaced by GaN device.The issue of oscillation,soft switching and magnetic parts in high frequency are analyzed,too.Finally,a high-frequency prototype is developed to verify the analysis of high-frequency oscillation and soft-switching characteristics.Besides,the power density is increased by about 50%,and the highest efficiency is nearly 91%.