Research On Rectifying Control System Of Electric Locomotive Auxiliary Converter

On modern electric locomotives,the power supply system on modern can be divided into two parts:traction converter system and auxiliary converter system.As an important part of electric locomotive,the normal operation of auxiliary converter system plays a very key role in whether the electric locomotive can operate normally or not.The research object of this paper is to study the rectifier system of electric locomotive auxiliary converter based on single-phase PWM rectifier,this paper mainly studies the mathematical model of PWM Rectifier and its control strategy,then improves the power factor of rectifier system by improves on the basis of indirect current control.On the basis of summarizing the research status of PWM rectifier at home and abroad,this paper analyzes and establishes the mathematical model of PWM rectifier.Aiming at the shortcoming that the indirect current control strategy relies too much on the main loop parameters and the reactive power consumption is too large,this paper introduces the current decoupling controller to decouple the AC side input current into active current and reactive current,reduce the reactive current of the input side to 0 by modulating the compensation coefficient,thus reducing the reactive power and improving the power factor of the system.In the control process,the most important part is the selection of compensation coefficient,If improper compensation may cause system shock.For that this paper propose a new indirect current control strategy based on current decoupling,which corrects the compensation coefficient by segmented nonlinear control according to the different range of the current power due value,so as to achieve a stable and rapid reduction of the phase difference between the voltage and current on the AC side,and then improve the power factor of the whole rectifier system.On the basis of theoretical analysis,MATLAB is used to build the simulation of the traditional indirect current control strategy and the improved strategy in this paper,the simulation results show that the advantages of the improved control strategy proposed in this paper.Finally the hardware design and software program of rectifier control system are completed,the small power experiment is completed on the test bench based on DSP-FPGA,the experimental results verify the feasibility of the improved control strategy proposed in this paper.