Conducted EMI suppression method based on obstructing grounding loops

For the problems of conducted EMI caused by SMPS without Y-capacitor..this paper proposed a method of obstructing conducted grounding loop, which can reduce the parasitic capacitance between primary and secondary winding of transformer effectively. A model of interference system including parasitic capacitance was built. The mechanism of the conducted EMI caused by grounding loop was discussed. And two shielding layers are applied to eliminate the parasitic capacitance. Finally, a SMPS without Y-capacitor was built and the experimental results were demonstrated to verify the effectiveness of the proposed method.