Conceptual Design of Isolated Power for Quench Detection System With Highly Insulating Stability Under Super High Field Magnets Using Wireless Power Transfer Technology

Abstract

The super high field magnets using superconducting wires have been promisingly applied for thermonuclear fusion power generation such as Korea Superconducting Tokamak Advanced Research (KSTAR) and International Thermonuclear experimental reactor (ITER) systems. The quench detection system (QDS) is essential for high reliability in the super high field magnet facilities. Generally, the quench voltage detection system, which uses resistive voltages, has been adopted. Such an ITER magnet, the maximum operation current and voltage of superconducting keeps over 60kA and 50 kV DC. Generally, in the case of medium power, the power transformer has been adopted for QDS as an isolated power due to stable insulating and durable characteristics. However, unfortunately, the magnetic saturation of electric steel for power transformer remained fragile as well as the volume is increased under super high field magnet. From this reason, authors suggest the electron quench detection device (EQDD) module. The main functions of EQDD are to convert high voltage signals of magnet into voltage-drop, and then send into quench monitoring system through optic cable. The EQDD module needs to isolate power system since EQDD module should be operated under high voltage insulation. From this reason, authors apply the wireless power system for EQDD module as a reasonable option instead of power transformer since the wireless power system can transfer power through any non-metallic media between resonance antenna (Tx) and receiver (Rx) coils. In this study, authors describe the possibility of conceptual design for quench detection system with high insulation under super high field magnet using wireless power transfer technology. As the EQDD including isolated wireless power should be electrically shielded, the shielding effects for Tx coil is investigated under different intervals of shielding barrier. Additionally, to expand the delivery distance between Tx and Rx coils, the operation and thermal characteristics for transfer efficiency are investigated under 370 kHz and 750 kHz RF generators, respectively.