Numerical Simulation of Superconducting Generator Based on the T–A Formulation

Due to the excellent electromagnetic properties of superconductor materials, superconducting generators have higher efficiency, lower weight and volume than traditional rotating machines. However, it is difficult to simulate the electromagnetic behavior in the superconducting generator due to the nonlinear E - J relationship. A numerical model based on the T - A formulation and moving mesh method is adopted to simulate the superconducting rotating machine, and the electromagnetic and mechanical behaviors of the superconducting rotating machine are investigated. The fully superconducting generator investigated in this article is radial type, which consists of field windings and armature windings made from YBa
₂
Cu
₃
O
_7-δ
(YBCO) superconducting race-track coils. The anisotropic field-dependent critical current density and the E - J power law relationship are considered in our model. The “virtual tape” model is introduced to calculate the induced current in the T - A formulation. The numerical results are obtained by the finite element method. The electromagnetic results calculated by our model are compared with results from the H - A formulation. The ac losses and stress distributions in superconducting coils are presented based on the T - A formulation. The results show that the body force and stress are periodic, and the stress will concentrate on the boundary of the coil. The magnetic field in the rotor is larger than that in the stator, and the field windings suffer greater body force and stress than the armature windings. This model has acceptable relative error with the H - A model for the time saved following T - A approach and relevance to mechanical calculations. Thus, this model can aid the design of superconducting rotating machines.