Researchon Control Strategies Of Electric Locomotive Auxiliary Converter

Auxiliary converter system of electric locomotives is an important part of electric locomotives, whether its working well or not affects the working state of the main traction converter circuit directly which is the key to the locomotive to run stably and safely. Based on the context of university-enterprise cooperation projects “Improvement of DJ1 electric locomotive auxiliary inverter”, more details is as follows:(1) Explains the classification and the topological structure of the front-end rectifier of electric locomotive auxiliary inverter. Analyses the working principle and modulation method of the four-quadrant PWM rectifier. And then, established the corresponding mathematical modes according to the switching function defined.(2) According to the modeling analysis, adopting the double closed loop control strategy, For PI current inner loop control unable to realize tracking the AC signal with no error, proportional resonant(PR) controller was designed to replace it. The MATLAB simulation and experimental results show that the PR controller can greatly improve the ability of current inner loop tracking sine signal. For the four quadrant PWM rectifier net side current distortion, the composite controller was adopted to replace the PI current inner loop controller. The MATLAB simulation and experimental results show that the composite control strategy can restrain harmonic current, improve the quality of electric current effectively.(3) Analyzed the influence of the ac component of the dc side voltage on the net side current, and designed digital notch filter according to the characteristic of the ac component. The MATLAB simulation results show that the notch filter can effectively filter out twice the fundamental frequency ac component and optimize the current inner loop control. At the same time, designed the digital phase locked loop(DPLL) based on FPGA and replaced the traditional two integration cycle as the delay link with one integration cycle to build the virtual orthogonal coordinate system. The MATLAB simulation results show that the digital phase-locked loop can track the input voltage signal quickly, and obtain strong anti-jamming capability.(4) Through the mechanical characteristics of asynchronous motor, got the control key of the constant voltage frequency ratio(V/f) control. Then built simulation model of SVPWM variable frequency speed regulation based on the five sections use the MATLAB/SIMULINK. The simulation results show that the V/f control based on space vector control can make the motor achieve better output characteristic.(5) Calculating the parameters of the power circuit devices of DJ1 electric locomotive auxiliary inverter, design the hardware and software of the electronic control box based on DSP + FPGA architecture. Then make the related experiment on prototype,verified the correctness and feasibility of the presented theory furtherly.