The Design And Realization Of High-efficient And High-precise DC-DC Electric Power Converter With Low Power

This thesis designs a High-efficient and High-precise DC-DC Electric Power Converterwith low power, it can convert a form of direct current into another form of direct current, itsmain function is to convert the given voltage and current and to charge the battery accordingto the proposed technology index.This designed DC-DC power converter is composed of three major components, thewhole bridge LLC resonant converter, crisscross Buck converter and auxiliary power. Thewhole bridge LLC resonant converter uses soft switch operation to complete the function ofvoltage matching and the isolation; Crisscross Buck converter is responsible for loweringvoltage and adjusting output voltage, which can recharge the battery; Auxiliary powerprovides all kinds of control voltage that needed by the high-efficient and high-preciseDC-DC power converter, having the extra wide range of the input voltage. This design alsouses LLC resonant converter and crisscross Buck converter in DC-DC power converter, notonly play the role of the isolation, but also improve the efficiency of the converter. Currently,the DC-DC power converter has been successfully developed to charge the battery.This thesis firstly introduces the research’s background and significance, thedevelopment of storage battery charging device and the soft switch technology. On this basis,the whole bridge with the topological structure is applied to design the high-efficient andhigh-precise DC-DC power converter. From the point of view of efficiency, the bridge typetopology is the preferred method, because it will let the primary winding loss down to theminimum and make the maximum use of transformer. In addition, the whole bridge circuit’sswitching current is only half of the half bridge circuit, which means reducing the loss of thecircuit.The overall design scheme analyzes the basic principle and function of whole bridgeLLC resonant converter and crisscross Buck converter, and designs the main loop of powerand other auxiliary circuit scheme. The whole bridge LLC resonant converter uses soft switchcontrol, which can realize ZVS and ZCS on the lord power components, reduce the openingloss and off loss of the lord power components, and improve the transformation efficiency ofDC-DC power converter; Crisscross Buck converter has two road input to make the outputcurrent ripple greatly reduced. In addition, this thesis makes selection and analysis of controlmodes of the high-efficient and high-precise DC-DC power converter.The thesis designs the whole bridge LLC resonant converter and crisscross Buck converter, and high frequency transformer is used to isolate them. The design content includesmain circuit parameter calculation, transformer design, main power components selection andloss calculation, resonant components selection and loss calculation, output filteringinductances selection and loss calculation, and the calculation of efficiency. On this basis, thecontrol circuit and drive circuit of whole bridge LLC resonant converter and crisscross Buckconverter are designed and analyzed.A battery charging device test platform is set up to make test, and to analyze the testwaveform and test data. Experimental results show that the design of the high-efficient andhigh-precise DC-DC power converter is of high performance, high efficiency, wide range ofoutput voltage etc, which can meet the expected technology index requirements.