詳細介紹了開關電源的設計,再励磁回路串接约为励磁绕组电阻值10倍的附加电阻来构成闭合电路，把同步电动机的定子直接接入电网，使之按异步电动机启动，当转速达到亚同步转速（95%）时，再切除附加电阻。-details of the switching power supply design, another exciting loop SERIES excitation winding resistance of about 10 times the value of additional resis