Research On Key Technology Of High Power And High Density Dc Power Supply Based On LLC Converter

The development of power electronics technology puts forward higher requirements of power level,power density,modularization and greening of the high power switch supply.LLC resonant converter,with its high efficiency and nearly sinusoidal low harmonic input current,becomes the first choice of the design of high-power DC-DC topology at present.However,the LLC resonant converter has many problems,such as complex design parameters,multi-iterative design process,serious nonlinear phenomena of components,difficulties in high-efficient heat dissipation,which has become the bottleneck of increasing the power density of high power supply.This thesis takes the 15 KW / 3U high-power high-density switching power supply as the research object,LLC resonant network parameter optimization and heat dissipating system design as key research contents,aiming at solving the key technological problems of high-power high-density DC power supply—efficiency and power density.This research mainly performs the following aspects:(1)Based on the first harmony analysis(FHA),this thesis summarizes the simplified process of the LLC resonant converter from the actual working circuit to the equivalent mathematical model,points out the key conditions of the LLC to realize the soft switch,and simulates the time domain waveform of the resonant converter in different working modes,provides guidance for engineering design.(2)To solve the problems of more resonant network parameters,unclear design flow and the mutual restriction of the high efficiency and the wide gain range in the LLC resonant converter,this thesis puts forward a new calculation method and flow of the resonant network parameter optimization,which is oriented towards application requirements in different occasions and provides a new way for the design of the resonant network.(3)Faced with the challenge that high-density high-power switching power supply needs high-efficient heat dissipation,this thesis designs a heat radiation structure oriented to high-density high-power switching power supply by the iterative optimization and rational distribution of air volume and fins based on multi-physics simulation tools.This heat radiation structure can better meet the dissipating requirements of high-density high-power switching power supply.Based on the research contents above,this research designs and builds the prototype of the power module and makes system test,in which the experimental prototype shows the working waveform of the LLC,the working temperature and so on,and validates the validity of the design theory.