Effective switching mode power supplies common mode noise cancellation technique with zero equipotential transformer models

In this paper a transformer construction technique is proposed that effectively cut off the Common Mode (CM) noise voltage passing across the isolated primary and secondary windings. This technique employs the Zero Equipotential Line theory to construct an anti-phase winding. It effectively cuts down CM noise by eliminating the noise voltage across the isolated primary and secondary windings. The concept of maintaining an equipotential line along the bobbin and quiet node connections are justified by analysis. A well considered transformer design with the proposed CM noise cancellation technique can achieve high conversion efficiency as well as good CM noise insulation.