Aiming at the suppression principle of switch power supply emi , this paper designs the magnetic core of emi filter , which includes the choice of common - mode inductor ' s material and the calculation of magnetic core ' s winding 摘要针对开关电源的电磁干扰抑制原理,设计了电磁干扰滤波器磁芯,包括共模感应器材料的选择,磁芯线圈的计算。