Performance Evaluation of Single-phase Solid-State Transformer for High-Speed Railway Propulsion

Abstract

For the supply of electric power to the High-speed Railway vehicle, the 25kV/60Hz AC source is connected to the power conversion system in the vehicle through a pantograph. The power conversion system in the high-speed railway vehicle consists of a bulky low-frequency transformer, which is used to step down the high AC voltage, and a DC/DC converter. Finally, the converted DC voltage is supplied to the inverter for motor traction. Thanks to the advance of power semiconductors and magnetic components, the power converter efficiency of the converter can be increased with reduced size. Therefore, a new concept of the transformer, called a Solid-State Transformer (SST), has been studied in recent years, substituting the bulky low-frequency transformer and DC/DC converter. In this paper, a 4.2MW SST is established, and the control method is proposed. The soft-start method of SST to diminish the inrush currents is also presented. The control and soft-start method is validated in the test setup with the reduced scale of SST. In addition, the thermally stable operation of the established module is also verified. © The Institution of Engineering & Technology 2024.