Digital Control Low Power DC-DC Modular Power Supply Design

With the development of switching power supply technology,power supplies are required to have smaller size,higher power density,expandability,data communication functions,and the like.This leads to the development of power supply towards modularization,high frequency and digitization.Module power technology emerges as the times require.With high power density,light weight and flexible use,it has gradually become the mainstream mode of equipment power supply.Based on the advantages of modular power supply,this thesis studies and designs a modular power supply which can input 3 80VDC bus voltage of single-phase power factor correction unit and output 28VDC.It can be used in aviation,military and other fields.The designed module power supply uses half-bridge LLC resonant topology and adopts digital control mode,which has high power density and efficiency.Firstly,this thesis introduces the research background of current module power supply,briefly describes the research status of low-power DC-DC module power supply at home and abroad,and analyzes two commonly used soft-switching resonant topologies,namely phase-shifted full-bridge topology and half-bridge LLC resonance topology.Half-bridge LLC resonant topology is selected as the main circuit topology.The working principle and working process of the half-bridge LLC resonant converter are studied.The unified FHA equivalent model of the half-bridge LLC resonant converter is established by the fundamental wave method.Using Matlab to draw the gain formula curve,find the factors affecting the gain of the LLC resonant converter,and provides a basis for the calculation of main circuit parameters.Secondly,the main circuit parameters of half-bridge LLC resonant converter are calculated to complete the selection of devices.Ansys Maxwell is used to simulate and design the planar transformer,and a planar transformer which meets the requirements of this design is made.According to the characteristics and parameters of the digital power supply control chip UCD3138A,the peripheral parameters of the digital control power supply are configured.The state machine digital power control algorithm is designed,and the power state,power protection and state switching program in power control are compiled.Finally,the correctness of the calculation and design of the resonant circuit parameters is verified by simulation,and the experimental prototype is made.The test results of the experimental prototype show that the design meets the expected indicators and can be further developed.