Persistent Current HTS Magnet for Maglev Applications

Abstract

Synopsis:This paper describes a persistent current HTS magnet that has been developed for Maglev applications. The HTS coil for the magnet consists of 12 single-pancake coils wound with four parallel Ag-sheathed Bi2223 wires. The HTS coil is connected with a persistent current switch (PCS) made of YBCO films and cooled below 20 K by a two-stage GM pulse-tube cryocooler. Detachable current leads are used to reduce heat leakage to the 1st stage of the cryocooler. The initial target for the current decay rate of the magnet was 10%/day. In order to achieve the target, wires with n-value of more than 14 in a range of 10 -9 -10 -6 V/cm at 77 K, 0 T were selected and coil winding processes were improved. As the result, a current decay rate of 0.44%/ day was obtained under persistent current operation of the HTS magnet. To observe the mechanical capability of the magnet, mechanical vibration tests up to ±15 G and electromagnetic vibration tests were carried out.

Magnetic Suspension System with Large Distance of 82 mm Using Persistent Current in Superconducting Coil

“…The electric circuit for the persistent current mode is shown in Figure 3. A superconducting coil, a persistent current switch (SW) and a DC power supply are the main components of the electric circuit [13]. After the persistent current SW is turned off, the DC power supply applies a constant current to the superconducting coil as shown in Figure 3a.…”

<b>Experimental Production and Evaluation of Racetrack Coils for REBCO On-board Magnet</b>

“…If a magnet is continuously energized with a power supply, the heat input through a pair of optimized current leads is approximately 0.1 W/A. With two pairs of 500 A current [5] leads, the heat input is 100 W (two sources of power supply per magnet). The heat input of 100 W is larger than the other heat inputs, such as radiation or conduction through support structures.…”

Optimal Control for a Superconducting Hybrid MagLev Transport System with Multirate Multisensors in a Smart Factory

“…This type is suitable for the above manufacturing process because all electromagnetic devices are installed on the track, so the electromagnetic impact of the system on transport logistics such as wafers and display panels is relatively low [ 12 , 13 , 14 ]. Additionally, the SH-EMS system allows for fast current control due to the lower electrical resistance of the superconductor compared to conventional formats, making it easy to compensate for the inherent instability of the MagLev system [ 15 , 16 , 17 ].…”