说明：  开关电源变压器磁芯多是在低磁场下使用的软磁材料，它有较高磁导率，低的矫顽力，高的电阻率。磁导率高，在一定线圈匝数时，通过不大的激磁电流就能承受较高的外加电压，因此，在输出一定功率要求下，可减轻磁芯体积。
(Switching power transformer cores are mostly used in low magnetic field of soft magnetic materials, it has a higher permeability, low coercivity, high resistivity. Permeability rate, a certain number of turns, through the small magnetizing current can withstand high voltage, therefore, a certain power in the output request, reduce the volume of the core.)