Iron-core superconducting magnet design and test results for Maglev application

摘要

Design and test results are presented for a superconducting electromagnet for levitating and propelling Maglev vehicles at high velocities. A U-shaped iron core carries a superconducting magnet around its back leg and a normal control coil around each leg of the U-core. The open side of the U-core is bridged by an iron rail through a large airgap between the poles of the U-core and the iron rail. The superconducting magnet is nominally designed to operate in a steady-state DC mode with current variations limited to rates less than 1 Hz. Faster flux variations due to gap changes are accommodated by current changes in the normal control coils. A feedback controller using the airgap and acceleration inputs controls current variations in the superconducting coil. Grumman has designed, fabricated and tested such an electromagnet. This test magnet is 2/3 of the full-size magnet that Grumman specified in their 1992 Concept Definition Study for the National Maglev Initiative. The purpose of these tests is to demonstrate the feasibility of operating and controlling a superconducting electromagnet in the specified environment. This paper discusses static magnet levitation characteristics as functions of airgap length and superconducting magnet excitation. Good correlation is observed between the calculated and measured performance.