Patent ID: 9692291
Date: 2017-06-27
CPC Classifications: H02M

Claim:
1. A noise filter connected to an external terminal through which an electric power conversion circuit is connected to an external device, the noise filter comprising a housing casing made of metal electrically grounded, and a first capacitor and a second capacitor which are accommodated in the housing casing, wherein a first electrode of each of the first capacitor and the second capacitor is electrically connected to the external terminal, a second electrode of each of the first capacitor and the second capacitor is electrically connected to the housing casing, and a current loop consists of the first capacitor, the second capacitor, the external terminal and the housing casing so that a first area and a second area is formed in the current loop, and a magnetic flux of an alternating magnetic field generated in a part of the electric power conversion circuit penetrates in the first area and the second area, a first induced noise current is induced in the current loop when the magnetic flux of the generated magnetic field penetrates in the first area, and a second induced noise current is induced in the current loop when the magnetic flux of the generated magnetic field penetrates in the second area, and the first induced noise current flows in a reverse direction to the second induced noise current.