Electromagnetic force behavior of superconducting bulks passing electromagnetic turnout

Abstract

High temperature superconducting (HTS) Maglev is a promising technology owing to its excellent electromagnetic properties of non-control stability and frictionless. As a critical component of HTS Maglev, the turnout poses challenges due to the use of the permanent magnet guideways (PMGs) that are difficult to switch mechanically. With simple structure and rapid responsiveness, electromagnetic turnout has become an interesting research field of HTS Maglev. The electromagnetic turnout is designed to control the electromagnetic force of the HTS bulks by adjusting the magnetic field using an electromagnetic-permanent magnetic structure. However, the magnetic field generated by the combination of the electromagnet and the PMs inevitably differs from the magnetic field above the PMGs, affecting the electromagnetic force behavior of the HTS bulks. To guarantee optimal performance of the electromagnetic turnout, the variation process of the magnetic field peak (MFP) above the turnout is analyzed. Furthermore, a three-dimensional superconducting model based on the H-formulation and motion equation is built to obtain the electromagnetic force of the HTS bulks passing the turnout. It’s concluded that higher cooling heights (CHs) in the preparation and higher working heights (WHs) in the turnout area are recommended to reduce the magnetic resistance and avoid the destabilizing effect. In addition, the smaller bulks experience greater resistance, and the longer bulks are prone to nodding, while the wider bulks are prone to shaking above the turnout. Properly matching HTS bulks with operating conditions improves electromagnetic force behavior and benefits HTS Maglev turnout passability.