Loss evaluation and simulation of superconducting magnetic bearings

Static and dynamic behaviors of axial flux SC magnetic bearings are very important for motor-generator design. Stability and losses were investigated both theoretically and experimentally, and spin down curves were calculated and measured. We derived the dynamic mechanical equations for axial SC bearings, and gave a mathematical frame which can include different spin-down models and loss components in which only macroscopic factors were taken into account. The elasticity of the bearings (lateral displacement) was taken into account on the basis of static force measurements. We suggested a mathematical description for the deceleration also, where each loss component was described by one appropriate coefficient. We also made a rather simple but effective superconductor model, which can be used in 2D or 3D finite difference or finite element methods. In this the superconductor was characterized by a maximum flux density gradient which has a close relation to the pinning forces, and is equivalent with a J_c value in 1D.