Based on the practice of designing single phase uninterruptable power supply(UPS), this paper introduces design of phase locked synchronous circuit for off line square wave UPS, on line USP equipped with and without output transformer.

• 通过单相不间断UPS电源的设计实践 ,介绍了后备式方波输出UPS、带输出变压器在线式UPS和无输出变压器在线式UPS锁相同步电路的设计。