부산대학교 도서관

The self-heating caused by the heat entering through the current supply conductor from the outside to the inside of the cryostat and by the energizing current in the power supply unit of the high-temperature superconducting coil magnet (hereafter referred to as HTS magnet) causes an increase in the cooling load of the cryocooler. As a countermeasure, a technique was devised to increase the superposition of the incoming current on HTS magnet current by multiple control of the time-division drive of a multi-parallel chopper installation inside the cryostat in order to reduce the energizing current of the conductors. The circuit simulation results confirmed that the circuit is valid for stable increase of magnet current up to the target value, including at startup, and for low ripple current values. In addition, the size of the main circuit board for magnet current 300A was also confirmed by a schematic design in combination with the short circuit of the HTS magnet using a parallel connection of low ON resistance MOSFETs. Excitation power supply for HTS magnet under study is intended for use with high-temperature superconducting non-insulated (NI) coil, but it may also be used for metallic superconducting magnets.