设计目标：完成输入：+12VDC或者220VAC；输出: 50V两路，每路输出达4A； 15V两路，输出电流无特殊要求； 12V两路，输出电流无特殊要求。所有输出电压只有正误差，无负误差，50V误差范围为+5V以内，其他两路的误差范围在+10 以内的设计，用PROTEL 99SE绘制系统电路原理图。-The design of the circuit from the input circuit, converter, control circuit, the output circuit of four main groups Into. Input circuit, including the EMI filter circuit, including switching converter circuit, switching power supply is the main channel transformation, complete with power supply waveform chopping modulation and output.