Research On270VDC Input500VA Three-phase Aeronautic Static Inverter

A two-stage three-phase Aeronautical Static Inverter (ASI) is being researched in this thesis.Based on the comprehensive investigation of the advantages and disadvantages of different strategies,and in order to meet the demand of wide input voltage range, high efficiency and high power densityof middle and low power ASI, the front end employs half-bridge LLC resonant converter; the secondstage selects three-phase dual buck topology as the DC-AC stage. The front end LLC resonantconverter is highlighted in this thesisFirstly, the disadvantages of low voltage DC power supply are analysed so that the high voltageDC power supply is obviously better. Then, by comparing some common insulated DC-DC converters,the asymmetric half-bridge LLC resonant converter is chosen for the front end. Owing to the resonantcharacteristics of itself, the converter can synchronously realize soft voltage switching of the powerswitches on primary and soft current switching of the diodes on secondary side without additionalbuffer circuit. Therefore, it can realize high efficiency and high power density. Moreover, it is alsoapplicable for wide input voltage range, low and middle power grade application and simple instructure. Secondly, by introducing three kind of resonant converters (SRC, PRC and SPRC)operation principles and analyzing the merits and demerits, the thesis makes preparation for inducingthe LLC resonant converter. Then the operation modes of the converter are presented by locating theswitching frequency in two conditions: fs>fr and fm<fs<fr. On that basis of equate the converter as atwo-port network, a completely improved precise parameter design strategy comes out in terms offrequency domain and time domain analysis.Besides, several ways to achieve high efficiency and high power density and stability arepresented. The integrated magnetics technique is analyzed by simulation on electro-magnetic fieldsimulation software. Also, over current protection technique is analyzed.Then, a550W LLC half-bridge resonant converter prototype is built, which involves detailedparameter design. Variable wavegraphs under different load verify the feasibility of the theoreticalstrategy. Finally, the two-stage debugging and efficiency test experiments are carried out. Theexperimental results verify the validity of analysis and design.