Reconfigurable Line-side Converter for DC Voltage Matching and Ripple Suppression in Multisystem Locomotives

The multisystem locomotive traction drive system (MLTDS) is fed by different kinds of railway traction power supply systems (TPSS). The direct connection of the DC TPSSs and the traction inverter are broadly adopted. However, the DC-link voltage is influenced by the variable and fluctuant catenary voltage, therefore wasting the capacity of the devices, complicating the wiring of motor as well as reducing the reliability of system. In this paper, the line-side converter, which is used as an AC/DC four-quadrant converter in AC supply system, is reconfigured as a DC/DC chopper for DC voltage matching in DC supply systems. The quadruple interleaved structure is adopted to eliminate the current ripple caused by the chopper. Firstly, structures and corresponding switching method of the reconfigurable line-side converter are introduced. With help of modal analysis, the principle of chopper operation, the mechanism and influencing factors of current ripple suppression are revealed. The system control method and configuration switching algorithm for voltage matching and stabilizing are then presented. Finally, the proposed conceives are validated by hardware-in-the-loop experiments.