Design Of High Frequency Isolation Auxiliary Inverter For Urban Rail Vehicles

As an important part of urban rail vehicle,auxiliary inverter is mainly responsible for providing stable electric energy for auxiliary load equipment on the vehicle,which is an important guarantee for the safe operation of the vehicle.Therefore,the research and design of auxiliary inverters for urban rail vehicles is of great significance.According to the requirements of the designed auxiliary inverter,this paper proposes a set of high frequency isolation auxiliary inverter topology,and carries out simulation verification.Firstly,the topology of the auxiliary inverter is compared and selected,and the high frequency isolation scheme is adopted.The main circuit is divided into DC/DC converter and DC/AC inverter,which mainly includes the staggered and parallel Buck converter,full-bridge converter and three-phase four-bridge arm inverter.Then according to the technical parameters of the auxiliary inverter,the main circuit of the components of the selection and design.Secondly,according to the small signal model of Buck converter,the interleash parallel Buck converter and full bridge converter are modeled,the relevant transfer function is derived,the closed-loop controller is designed,and the Bode diagram of the system is analyzed.The results show that the DC/DC converter has good static and dynamic performance.Then,on the three-phase inverter voltage imbalance principle analysis,and analyzes the various coordinates of each sequence component,using the theory of symmetrical component method and coordinate transformation will each sequence component decomposition,design the positive sequence and negative sequence components in the rotating coordinate system of the PI controller,and the static coordinate system of the zero sequence components in the PR controller.Three-dimensional space voltage vector modulation(3D-SVPWM)in static coordinate system is selected as the control algorithm of three-phase four-bridge inverter.The3D-SVPWM algorithm is analyzed in detail and realized by simulation.The simulation results are consistent with the theory.Finally,in Matlab/Simulink software,a DC/DC converter model including interleash Buck converter and full-bridge converter,as well as a three-phase four-bridge arm inverter model are built,and the simulation verification is carried out respectively.The results show that: The DC/DC converter can meet the requirements of output voltage stability in a wide range of input voltage and load mutation conditions.The three-phase four-jib inverter can output high quality three-phase balanced voltage under balanced,unbalanced,one-phase missing and load mutation conditions.