Electro-Magnetic Design of a 3MJ YBCO Magnet

The electro-magnetic design of two 3 MJ superconducting magnetic energy storage (SMES) magnets with YBCO conductor are presented. One magnet is with solenoidal geometry composed of double pancake coils, and the other one is with toroidal geometry. According to the magnetic field simulation results, the perpendicular componet of the magnetic field of the toroidal magnet could be extremely reduced compared with the solenoidal geometry. Therefore, a lower YBCO conductor requirement could be expected due to the dependence of Jc vs B performance of the YBCO conductor. Besides, the lower leakage magnetic field is important for application. A SMES system of 3 MJ is considered, and the coil is made of multiple identical D-type pancake coils. The critical current of the used YBCO conductor at 30K is 270A under 1 T perpendicular magnetic field. The inner radius of the D-type curve is 500 mm, and the outer radius is 1000 mm. The SMES magnet is made of 96 pancake coils, where the rated operating current is 975 A and the maximum perpendicular and parallel magnetic flux density are 0.5 T and 4.0 T, respectively. Further more, the maximum hoop stress and radial stress are 283 MPa and 78 MPa.