Patent ID: 7868730

Claim:
A filtering device connected to an AC power supply, comprising: a common-mode inductor comprising a winding on each line of the power supply; and a magnetic core made up of a first torus and a second torus, the first torus being juxtaposed with respect to the second torus, wherein the first torus is made from a first nanocrystalline material having a first magnetic permeability and the second torus is made from a second material having a second magnetic permeability; a saturation induction of the first material is substantially equal to or greater than a saturation induction of the second material, and the first magnetic permeability is equal to or greater than three times the second magnetic permeability at a frequency of 10 kHz of a current flowing through the windings to prevent the common-mode inductor from saturating in a resonant frequency range of the filtering device.