Study On Interaction Between Converters And On-Board Electrical Equipments For AC Drive Locomotive

With high speed railways developed rapidly around the world, AC drive technology becomes the symbol of the world's high-tech traction power as well as the main developmental direction of China's railway traction in the future. As a core subsystem of AC drive system for electric locomotive, line side converter system takes charge of maintaining voltage stability of middle DC link, suppressing harmonic wave of AC side by making AC current as a sine wave, making power factor approach 1, the working condition of which is vital to the performance of drive system. Meanwhile, the insulation of traction motor has direct impact on the stability and reliability of electric locomotive. Interaction between converters and on-board electrical equipments for AC drive locomotive is studied in the theis.Firstly, simulation model of line side converter system for AC drive locomotives is built by utilizing Matlab/simulink. The coverter is quadruple PWM rectifier with the strategy of transient current control, and the DC load is simulated by a resistance. Compared with measured data, the simulation model can simulate the working condition of converter.Secondly, the influence of transformer leakage inductance and mutual inductance between windings to the performance of four-quadrant converter (4QC) is researched. To meet the performance of current tracing, limit of the maximal modulation ratio and fluctuation of catenary voltage, an integrated scheme is put forward to design the inductance parameter of AC line for 4QC. Furthermore, the results of simulation verify the feasibility and correctness of the proposed method. And it is indicated that harmonic currents of windings will increase with enlargement of winding current fluctuation when mutual inductance between windings increases.Thirdly, the copper loss and iron loss of locomotive transformer in harmonics condition is calculated. Moreover, by utilizing ANSOFT, the swirl characteristics of silicon steel sheet is analyzed, and iron loss of transformer is calculated with finite element method.Last but not least, in order to test insulation properties under continuous impulses, a new insulation aging test system is used to simulate the aging effect of converter on the winding insulation in the inverter-fed motors. The influence of impulse amplitude and frequency on insulation lifetime is investigated by using polyimide film as experimental material. Finally, an insulation electrical aging lifetime model is proposed.Research in the thesis provides theoretical basis for 4QC and transformer optimization design. At the same time, it's also the basis of further research on insulation failure mechanism of insulation material for traction motor.