Power Supply System Design For Railway Maintenance Camping Car

With the development of high performance digital chips such as DSP, FPGAappears, and as its powerful data processing ability and high running speed, DSPattracts widespread attention among the academic and engineering circles. Studies ofrailway maintenance camping car power supply system, based on DSP control, havereceived more and more concern at home and abroad. For railway maintenancecamping vehicle power system, in this paper, on the basis of the hardware frameworkof the system, DC filter and AC filter parameter design has been made by bothengineering experience and simulation combination method, and for the DC filtersmoothing inductance and smoothing capacitor parameter design, and two kinds ofpractical design ideas have been put forward. System enable its rectifier module,charging module and inverter module to be in digital control using incremental PIalgorithm, simulation and experimental results show that the rationality of the systemdesign of the filter parameters and incremental PI control algorithm. For power system,the harmonic content is a core measure of the power quality. For its popularization andapplication, study of system hardware and software design and the realization of theharmonic suppression has important practical significance.This paper first introduces research background of camping car power supplysystem, and then its different power supply modes are compared, and then currentsituation and progress of the research on contact net power supply system.The overallcontrol thought and the system hardware framework has been put forward based onsystem control requirements and the design goal. Then the paper introduces thetopology structure and design of main parameters, including rectifier module,charging module, and inverter module. This paper puts emphasis on introduction ofthe DC filter and AC filter parameter design method, and the simulation experiment tovalidate its feasibility.The article then explains working principle of phase-lockedfrequency dividing circuit, to accurately capture the synchronous voltagezero-crossing synchronous, also two digital input and output interface circuits, andanalog ones.Secondly, this paper introduces in detail the digital PID algorithms, and gives arectifier module PID control algorithm aiming at the camping vehicle power system.At the same time, introduced the concrete realization of three-phase inverter SPWMalgorithm with DSP, gives control flow diagrams and description of main modules. Then, the harmonic distribution of single phase half-control rectifier has been putforward to the point, based on the basic Fourier analysis theory. In the meantime, adetailed derivation for harmonic distribution has been shown, on the SPWM wave ofthree-phase full-control bridge. For rectifier module and inverter modules，practicalmethods for harmonic suppression have been presented.Finally, according to the correspondence of three-phase SPWM inverterswitching function and phase voltage, balance equation of phase voltage under staticcoordinates has been achieved. According to the coordinate transformation theory,mathematical mode of the three-phase inverter has been got in a two-phasesynchronous rotating coordinate system, and then draws the PI of three-phase SPWMinverter with constant frequency and voltage based on the synchronous coordinate.In order to verify the harmonics distribution, experiments in three cases has been puton, including load balancing along with fixed carrier frequency three-phase,three-phase unbalanced load along with fixed carrier frequency, balanced three-phaseload along with different carrier frequencies. At the end of the article, harmonicanalysis on railway maintenance camping vehicle power supply system experimentalprototype have been given.