Application And Research On Bidirectional Converter Of Traction Power Supply For Urban Rail Transit

With the development of economy and the acceleration of urbanization,the population and motor vehicles in big cities are more and more,which makes the traffic pressure and the environmental pressure are larger and larger.The evelopment of subway,light rail and other urban rail transit has become an effective measure to alleviate the problem.However,the power supply of urban rail transit is still used the diode rectifier and braking resistor,which caused serious waste of the energy resources.PWM converter is a very good solution,but there are still many technical problems need to be solved.This paper summarizes the research process and industrial application of the bidirectional inverter for traction power supply of rail transit.According to the requirements of working conditions,it gradually develops around several major technical problems and research focuses,mainly involving multiple parallel technology,the optimization design of three-level main circuit topology,system communication and control method,device selection and hardware design,hybrid power supply control strategy,system simulation,the type testing and field-industrial application.In order to reduce the floor space of the bidirectional converter,the system scheme of the bidirectional converter is discussed firstly.Aiming at the optimization design of the three-level main circuit topology,the multiple parallel technologies of bridge parallel,unit parallel and cabinet parallel are developed.The synchronous pulse trigger and carrier phase-shift modulation strategy are adopted in the pulse control,and the high power density cabinet is developed successfully.In the system control scheme,the communication scheme and control strategy between DSP,PLC and HMI are mainly researched and developed,and the optimization design of the software is carried out in order to adapt the working conditions and protections.In the third chapter,the system hardware and key components are designed and selected,mainly includes the selection of IGBT,capacitor and high impedance split winding transformer,and verifies the rationality of component selection through thermal simulation.At the same time,the hardware board is designed and manufactured,and the system control is simulated by MATLAB to check the rationality of the software and hardware design of the system.After the successful manufacture of the prototype,the hardware and software design of the bidirectionalconverter is tested through double-pulse test of the module,electrical performance test and electromagnetic compatibility test.The fourth chapter of this paper focuses on the hybrid-power supply strategy of the bidirectional converter,which lays the foundation for the field application of the bidirectional converter.At the end of this paper,the operation and test data of the bidirectional converter after its application in the field are discussed in detail.The characteristics of the bidirectional converter's hybrid power supply mode and the stabilized voltage power supply mode are analyzed.The influence of the bidirectional converter's application in the field on the power distribution,cross-area power supply,rail position and contact network voltage fluctuation is tested and analyzed.At the same time,the bidirectional converter is also tested and analyzed of the peak capacity,the datas of power supply and feedback and distributed reactive power compensation capability of the device are verified.The measured data show that the bidirectional converter has the ability to replace the diode rectifier unit and energy-feedback device.It has the advantages of small floor area,small DC network voltage fluctuation,optimization of quality at power supply,reduction of the cross area power supply,reduction of the loss,reduction of rail potential and so on.It has high promotion and application value.