Research On Cascaded Aeronautic Static Inverter With Dual Output

In recent years,with the continuous development of the aviation industry,aeronautic static inverters in low voltage aircraft power system continue to move towards high efficiency,high power density and high reliability.At the same time,in specific applications,these aeronautic static inverters also need to have the ability of high voltage gain and adapt to a wide range of input voltage.Therefore,the design of this kind of aeronautic static inverter is challenging.This paper takes the aeronautic static inverter with 28V DC input and 115V/400Hz?26V/400Hz AC output as the research object.The scheme selection of main power circuit of the aeronautic static inverter is carried out,and the working principle of all the converters are introduced.Aiming at the power backflow problem of synchronous rectifier Boost converter in the front stage of aeronautic static inverter,a power backflow suppression strategy based on recursive least square(RLS)method and kernel density estimation(KDE)is proposed.Aiming at the full bridge inverter,the design of power circuit,control system,the damping strategy of resonant peak in LC filter are studied.Finally,the feasibility of the hardware and software parameter design is verified by experiment.The specific research contents are as follows:1.According to the requirements of related index,after analyzing the advantages and disadvantages of the feasible scheme for main power circuit,the scheme of interleaving Boost converter?two independent full-bridge LLC resonant converter+two independent full bridge inverters is selected.The working principles of interleaving Boost converter,full-bridge LLC resonant converter and full bridge inverters are introduced.2.Aiming at the problem of power backflow in front-stage synchronous Boost converter under no load and light load,the circuit modes and working characteristics are analyzed when power backflow exists,and the basic power backflow suppression strategy is given.In order to ensure the accuracy and efficiency of the strategy,RLS and KDE are introduced on the basis of the power backflow suppression strategy.RLS and KDE reduce the influence of inductance errors and sampling errors on strategy accuracy.3.The main power circuit parameters of the full bridge inverter are designed.The control diagram of the full bridge inverter is analyzed.The transfer functions of the control loop of the full bridge inverter are obtained according to the control diagram,and the parameters of the PR controller are designed based on the bode diagram.Aiming at the problem of waveform distortion and stability decrease of control loop caused by resonant peak of LC filter in bode diagram when full bridge inverter is in no-load mode,an active damping strategy based on capacitor current is proposed to suppress the effect of the resonant peak.4.According to the design parameters,an experimental platform of cascaded dual-output aeronautic static inverter is built.The anti-interference measures of the hardware circuit are studied and the hardware circuit of the inverter is designed.This paper introduces a method of soft startup in software design and a software method for short circuit protection of 26V/400Hz output and the block diagram of system program.Finally,the main project indexes are tested on the experimental platform.The feasibility of the power backflow suppression strategy of synchronous Boost converter based on RLS and KDE and the control strategy based on incomplete differential capacitor voltage of active damping are verified.