说明：  这是一个用MATLAB/simulink搭建的AC-DC模型，先将220V交流电降压后，经过整流、滤波后变为平直的直流电，然后经过一个Buck电路，通过调节占空比，将输出电压、电流稳定在25V、5A
(This is a AC-DC model built with MATLAB/simulink. After the 220V AC is depressurization, after rectification and filtering, it becomes straight DC, and then through a Buck circuit, the output voltage and current are stabilized in 25V and 5A by adjusting the duty cycle.)