Patent ID: 6897718

Claim:
An active filter comprising: a boosting converter circuit comprising: a switching element; a coil provided with a magnetic core generating a back electromotive force when the switching element breaks a DC current, wherein the magnetic core comprises molded article of a mixture of a glassy alloy powder and an insulating material, the glassy alloy powder having a texture primarily composed of an amorphous phase and exhibiting a temperature difference ΔT x , which is represented by the equation ΔT x =T x −T g , of at least 20° K. in a supercooled liquid, wherein T x indicates the crystallization temperature and T g indicates the glass transition temperature; a rectifying element connected in series in the forward direction to the coil provided with the magnetic core for rectifying a current generated by the back electromotive force; and a capacitor for smoothing the rectified current; and a control unit for controlling the switching interval of the switching element of the boosting converter circuit.