Research On 270V/28V Aviation Bidirectional DC/DC Converter

Owing to the extensive use of electric actuator instead of hydraulic equipment and pneumatic equipment,the more/all electric aircraft can effectively reduce the pollution of the environment,together with the improvement of the performance,reliability,maintainability when compared with the traditional aircrafts.Bidirectional DC/DC converters,as the crucial component of the more/all electric aircraft power supply system,are of great importance to the development of the more/all electric aircraft.Therefore,the research on high efficiency,high power density bidirectional DC/DC converters admits of no delay.In this paper,a bidirectional LLC resonant converter based on bidirectional full-bridge DC/DC converter and LLC resonant technique is studied.The working principle and basic characteristics of the converter are analyzed,depending on which a parameter design method is proposed and the design procedure of the aviation 270V/28 V bidirectional DC/DC is given.Also,the small signal model of the converter is established using the first harmonic approximation.Since it is difficult to obtain the analytic solution of the output transfer function from the seven-order small signal model,the small signal model is reduced.Based on the obtained open-loop transfer function,the dynamic and steady-state characteristic of the system is analyzed.Also,the system control block diagram is established.Then,to meet the application of bidirectional LLC resonant converter under low voltage and high current circumstance.The digital Implementation of Synchronous Rectifier Driving Scheme is studied.The influence of synchronous rectification duty cycle to the output voltage is measured,and a synchronous rectification strategy based on the output voltage sampling and variable step disturbance observation method without additional sensor is given.Finally,a simulation model is built in MATLAB/SIMULINK and a 270V/28 V 1kW prototype is fabricated to verify the theory.The experiment shows that the peak efficiency can reach up to 96%.