Analysis Of DC/DC Converter In Maglev Train 24V Power Supply And Improve Design For Spare Parts

The localization for spare parts in Shanghai high-speed maglev train has not been implemented.So maintenance costs for maglev train is high.The damage rate of DC\DC converter for the 24V power supply system is high.Therefore,research and analysis for the converter based on half bridge zero voltage switched multi-resonant converter converter has obvious significance.On this basis,the original converter topology can be improved based on the theory of LLC converter.It will be conducive to further reduce the weight and cost.In this paper,the improved design for the 24V DC/DC converter based on LLC converter and maximum current automatic current sharing method is studied.Firstly,this paper analyzes the working states and theoretical waveforms of the main circuit of the half-bridge multi-resonant converter topology used in the vehicle power converter,and studies the principle of droop current sharing and input voltage feedforward control.Due to the parameters of this board are difficult to directly determine,in this paper,based on the theoretical analysis,the parameters of the main circuit and the parameters of the control and current sharing circuit are recalculated and selected.And then in the completion of the circuit simulation on the basis of a trial prototype to experiment.Through the experiment to verify the correctness of the circuit design,will be conducive to the maintenance of the spare parts and deep study.In view of the original power design stereotypes early,there are some problems of the original converter such as the high hardware costs,the high weight,rectifier diodes may have duty cycle loss,and the speed of diodes switching may be slow and other issues.This paper introduced the LLC converter to replace the original half bridge multi-resonant topology.This paper analyzes the working principle and characteristics of the main circuit of the LLC converter,and calculates the main circuit parameters and completes the component selection.In view of the current power panel droop method are simple flow,the problem of low voltage regulation rate,this paper introduces the principle of maximum current automatic current sharing method and selects chip UC3907 to improve current sharing control circuit,selects chip ICE2HSOIG to improve control circuit.Finally,this paper improves the monitoring and protection of the circuit structure,this circuit can provide more protection measures and more monitoring object for converter.In this paper,a multi-module parallel simulation is carried out by PSIM software,and a 400W LLC dual-module parallel experimental platform is built.The correctness of theory and design is verified by experiments.The experimental results show that the power efficiency improvement board based on LLC structure developed in this paper can achieve high efficiency and current sharing accuracy.Under the rated input voltage and rated load conditions,the prototype can achieve a maximum efficiency of 92.5%and 2.31%of the current sharing error.The development of the power prototype to achieve the desired purpose,for the 24V grid equipment,a comprehensive domestic research has laid a solid foundation.