Levitation Performance Evolution of HTS Maglev Systems Under Thermally Induced Magnetic Irregularities in Permanent Magnet Guideways

The flux pinning between the high-temperature superconducting (HTS) bulks and the permanent magnet guideway (PMG) ensures the stable levitation of HTS maglev. Environmental parameters impact the temperature field of the HTS maglev rail beam, while thermal-magnetic effects cause magnetic field decay and fluctuations above the PMG, leading to additional excitation on the HTS maglev vehicle. This paper develops a heat transfer model based on three months of PMG temperature measurements from an HTS maglev test line. A thermal-magnetic coupling model for the PMG is also constructed to link environmental parameters with HTS maglev levitation performance. The analysis presented here identifies 22.69% irreversible demagnetization and 5.72% reversible magnetic field fluctuations, contributing to periodic changes in levitation performance. The proposed calculation method and measurement approach provide valuable references for the state identification, operational maintenance, and safety management of maglev systems.