A Neodymium permanent magnet fault current limiter for use in the FREEDM project

A novel Neodymium (NdFeB) based fault current limiter for the National Science Foundation´s FREEDM Project is presented in the paper. The proposed device incorporates a fast mechanical contact switch in parallel with the NdFeB core. The proposed fault current limiter exploits the nonlinear characteristics of the ferromagnetic core. The hysteretic properties of the ferromagnetic core are modeled by the Preisach method of Hysteresis. Finite Element Analysis is performed on the coils of the proposed device and the results are displayed. A low voltage simulation is done to determine the feasibility of the proposed device and to determine the correct operation. The simulations show the NdFeB fault current limiter can limit the potential fault current by the required 50%. Also, harmonic analysis is performed and is determined the NdFeB fault current limiter does not inject any additional harmonics into the FREEDM system.