Engineering design of step-up transformer for inverter type high voltage DC power supply

The neutral beam injection system in the Chinese Fusion Engineering Test Reactor(CFETR) is used for auxiliary heating of the plasma, it is necessary to create an acceleration grid power supply to provide energy for the plasma. The high voltage power supply adopts the inverter type power supply scheme, in which the step-up transformer plays the role of voltage isolation and power transformation between the primary and secondary sides, and is the key equipment to determine the voltage level and safety of the high voltage power supply. In addition to the general characteristics of large capacity and high voltage class, the transformer also needs to meet the requirements of operating under unusual frequency and high harmonic input. According to the requirements of step-up transformer, this paper reports the engineering design of the transformer, including the calculation of key parameters, the design of the main electromagnetic structure, such as core and winding of transformer, simulation of transformer insulation level for the standard input voltage, research about winding loss and temperature rise caused by higher harmonic. It lays the foundation for the future construction of CFETR N-NBI system.