Research On Grid-Side Converter Of High-Speed Emu

With the rapid development of railway, research on technology related high-speed is gaining more and more attention. As an important component of the traction system of the high-speed EMU, Network-side converter is important guarantee for reducing the harmonic pollution on railway power grid and stable and safe operation of high-speed train. Therefore, it is necessary to indepthly study network-side converter of high-speed train.High Speed Network-side converter uses the four-quadrant PWM rectifier with high power factor and low harmonic pollution, which uses mainly three-level and two-level Rectification technology. In this paper,the single-phase three-level and two-level four-quadrant rectifier was used as the research object, with the analysis and research of transient current and predictive control of two different control methods in the two rectification application.Firstly, this paper introduced the single-phase three-level rectifier and the two single-phase rectifier with the working principle,operating mode, and the establishment of the mathematical model.Secondly, this paper introduced several control strategy applied pulse rectifier, and researched mainly the transient current and predictive control, and analysised SPWM modulation techniques used in the two rectifiers.The mid-point balancing methods used in three-level rectifier was described, which ensures the three-level rectifier good work performance. Simultaneously, this paper analysis the carrier phase shifting method of duplicate rectifier, which descreases current harmonic distortion rates in the transformer primary side. The effects of some of important parameters in rectification was introducted and the parameters of AC inductors, DC capacitors and DC filter meeting the steady state performance and dynamic response was obtained by theoretical analysis.The simulation model of the two rectification technology based on the transient current and predictive current control were established and analyzed by using the MATLAB/SIMULINK software.Through the analysis and comparison, The simulation results show that predictive controlling with good dynamic response, stable performance and simple structure can be also applied to high-power AC drive occasions as the transient current controlling. The two-level and three-level rectifier show high power factor, stable DC voltage and smooth switching between the traction and regeneration and grid voltage conditions. The three-level rectifier descreases current harmonic distortion rates and the switch stress is small, but need to balance the neutral-point voltage, and the system controlling is relatively complex; The two-level rectifier is relatively simple and effective switching frequency is high with the large output capacity. but it show higher current harmonics rates than the three-level rectifier.