In the development of switching power supply, electromagnetic interference(EMI) should be much attended. This paper investigated the transmission mechanism of conducted common-mode(CM) noise in a-single-switch forward converter. Based on the analysis, a CM transmission mode can be built. Through theory analysis, methods of designing circuit structure and transformer construction can improve CM noise. Experimental results validated the proposed model and the developed CM noise reduction techniques.

Conducted common-mode noise;electromagnetic interference(EMI);forward converter;distributed capacitance