2004 Volume 124 Issue 9 Pages 893-900
A newly proposed “Active Noise Filter" is implemented to reduce both normal and common mode conducted EMI noise generated by inverter system. The Active Noise Filter detects the conducted noise through high pass filter, controls the EMI noise voltage by feedback loop with operational amplifiers and low-voltage-rated transistors. It does not have any common mode transformers, therefore there is no problem of the iron core saturation. The EMI noise with an inverter system is measured using a line impedance stabilization network (LISN), and it is shown that both normal and common mode noise currents are significantly reduced. Moreover, conducted EMI noise measured at the LISN is reduced by 20 dB in the hundreads kHz of the frequency range. The results explain that the conducted EMI noise can be attenuated without any filter reactors using iron cores which predominantly decide the size of EMI noise filters.