Currently, the railway locomotive and vehicle auxiliary power supply adopts an advanced centralized DC 600V power supply system followed by a decentralized variable frequency power supply for passenger cars. Both locomotives and passenger cars require a control power supply that converts from DC 600V to DC 110V. This direct-to-direct conversion is achieved using high-frequency isolation frequency converters. The present achievement has developed a 15kW high-frequency isolation direct-to-direct converter with a 110V control power supply for use on locomotive and EMU vehicles. By simply raising the blocking voltage level of the IGBT devices in the scheme, an appropriate transformation can be made to develop a high-frequency isolation DC/DC 110V control power supply for urban subway and light rail vehicles.