Study on coil winding configuration for Superconducting Magnetic Energy Storage

Superconducting Magnetic Energy Storage (SMES) is very promising for the future power storage system because of fast response, low loss and high efficiency. Strong magnetic field is very favorable for SMES because it promises a compact device. However, the huge electromagnetic forces caused by strong magnetic fields and coil current becomes a serious problem. We propose the Force-balanced Coil (FBC) concept for the SMES which drastically reduces the huge centering forces by balancing it with the hoop forces induced by the toroidal current. Superconductor stress, length, maximum field and stored energy were surveyed. The results were compared with the toroidal type configuration and ordinary helical type one, It is shown that Force-balanced Coil is more compact than the others in view point of electromagnetic force and per-unit length stored energy of the superconductor and has a potential for simplifying the supporting structure, making the facility compact.