A Three-Phase to Single-Phase AC-DC-AC Topology Based on Multi-Converter in AC Electric Railway Application

An AC-DC-AC topology based on multi-converter is proposed in this paper. It can match the capacity of the converter for high voltage and large power applications. This structure is not only suitable for solving the power quality problems of electrified railways, but also has its own superiorities. Its architecture and advantages in the traction application are analyzed in depth, and the design calculation of the main elements is presented. The control system of the proposed topology is designed, where dc current feedforward control is adopted to relieve the impact of the load mutation on the system. Its modular structure and simple current sharing control provide convenience for the capacity expansion. The software simulation and experiment based on a 45kVA prototype validate the proposed structure, and they are all compared with the traditional power supply systems. The simulation results indicate that this topology can not only satisfy the voltage and power requirements of traction load and solve the power quality problems, but also have its own superiorities in the application of electrified railways. The experimental results verify the correctness and validity of the scheme.