2013 Volume 133 Issue 11 Pages 1097-1103
Levitation characteristics of an electrodynamic suspension device using AC electromagnets driven by a high frequency current are influenced by the skin effect. The skin depth depends on the frequency of the exciting current, thickness of the nonmagnetic conductor, and electrical conductivity. The frequency that enables the levitation is estimated by measuring frequency characteristics of the lift force and the secondary copper loss and then calculating the temperature rise per second from the secondary loss when the nonmagnetic conductor thickness and electrical conductivity are changed. In addition, the thickness of the nonmagnetic conductor suitable for each drive condition is determined from the frequency characteristics. The measurement results of the frequency characteristics of the levitation device showed that the levitation frequency depends on the conductor thickness and the electrical conductivity. The results also show that the suitable frequency for each drive condition depends on the electrical conductivity of the nonmagnetic conductor.