Measurement of Magnetic Materials at Room and Cryogenic Temperature for Their Application to Superconducting Wind Generators

Compact, lightweight, and large-scale generators are desired for offshore wind energy application due to transportation and installation requirements. In order to reduce the levelized cost of wind energy, ever-larger wind turbines are under research and superconducting wind generators are proposed as they have high power density and light weight. Due to the still high price of the superconductor, an iron core is usually employed to reduce consumption of the superconductor as well as to divert the flux direction away from superconductor. However, in many designs and studies, losses and permeability of the silicon lamination sheets used at cryogenic temperature are taken from the values at room temperature, which is not appropriate. Hence, the performance of the silicon lamination sheets at low temperature is essential. Magnetic properties tests of toroidal cores at both room temperature and 77 K with four different materials were made and the results show that the permeability of silicon sheets and losses are higher at 77 K than room temperature.