Common mode filtering can suppress fast transiented group interferences problems with repetition rates of several kilohertz at certain user positions It can filter out single or more harmonics in the power supply and purifying the direct current power supply The circuit consists of three parts, the first part is a single-stage filter circuit, the second part is a common mode filter, and the third part is a two-stage filter circuit Efficient filtering, combined with filters, effectively suppresses common mode and harmonics filter, commonly known as passive filter, is a traditional direct current harmonics compensation device compose of inductance and capacitance