Research of Buck-Boost Converter for Trains

A new type of converter for train was designed.The input voltage of the converter is from 35 V to 90 V and the output voltage is 50 V.The rated output power of the converter is 300 W.The Buck-Boost topology was adopted in the main circuit,and the two parallel MOSFETs were driven respectively by means of complementary control.The SG3525 which can give out two complementary PWM signal was used as controller.The small-signal model of the buck-boost converter in Continuous Conduction Mode(CCM) was built by state-space average method,and the control-to-output transfer function of the power link was deduced.The bode diagrams of the open-loop transfer function were drawn using in Matlab,and the double poles-double zeros compensating network was designed and the parameters were calculated through analyzing characteristics of bode diagrams.The simulation model of the converter was established by Matlab/Simulink and the simulation result was given.Within the range of the changes of the input voltage,a series of experiments in light load and heavy load were made.The Simulation and experimental results are presented to verify the validity of and correctness of the method and the theory.