Research on the secondary pulse suppression technology of DC voltage for Hybrid EMU

Due to the single-phase power supply characteristics of electrified railway, the traction system-front four-quadrant rectifier input instantaneous power will have secondary pulsation, resulting in the DC link to generate the corresponding secondary pulsation voltage. Aiming at the disadvantage of passive secondary resonant branch to eliminate voltage pulsation, this paper adopts active power decoupling circuit to achieve good filtering effect and effectively resist the interference of network side frequency offset. In this paper, the mechanism and influence of the secondary voltage pulsation of the intermediate DC bus are analyzed firstly. Then, based on the established Buck APF mathematical model, the current closed-loop design based on the quasi-PR controller and the voltage outer loop design based on the PI controller are completed according to the control objectives. Finally, the effectiveness of the proposed method is verified by simulation and experiment.