Proposal of an active common-mode filter capable of reducing radiated EMI from power cables

Power electronics devices can cause serious electromagnetic interference (EMI) because of their high-speed switching. Such switching disturbances then propagate along power cables, which can act as antennas to radiate noise. Typically, a passive filter composed of inductors and capacitors is used to reduce EMI. However, when a power cable is connected to the passive filter, the cable acts as a distributed constant line that worsens the attenuation characteristic of the passive filter at the anti-resonant frequencies of the cable. This study proposes a solution to this problem in the form of an active common-mode filter that uses a high-speed amplifier. Experimental results show that the proposed filter improves the attenuation characteristics of the passive filter and reduces radiated noise from the cable over a wide range of frequencies from 10MHz to 100 MHz.