A Proposed Fast Charging and High-Power System for Wireless Railway Trains Adopting the Input Voltage Sharing Topology and the Balancing Control Scheme

In this article, we deal with the onboard fast energy conversion system (FECS) that is installed in a wireless railway train (WRT), which receives electrical energy not from the wayside device but from the onboard device when traveling between stations, after getting such energy stored by fast charging during its stopping time at a station. The adopted input-series and output-independent architecture and the interleaving topology can reduce the size and weight of onboard FECS for 1500 V, which is double the operating voltage of the existing 750 V operating voltage. This allows 1200 V class insulated-gate bipolar transistor applications to increase switching frequency and reduce passive component volume. In addition, in order to secure system stability, which is important in any transportation system, a WRT must operate on the basis of simple control. Through a simple and efficient balance control based on a variable current limiter, the input voltage unbalance caused by the input voltage sharing is resolved. Also, it can control charging and discharging based on the energy moving characteristic of the train operation pattern and connection with a high-power energy storage pack. The performance of the onboard FECS at 1500 V with the proposed method is experimentally verified on a 600 kW prototype system.