In order to realize the frequency and phase of output voltage synchronized with input voltage when UPS works, in the paper, a digital phase locked loop based on MCU with high precision is presented.

• 为了实现不问断电源(UPS)运行时输入输出电压频率和相位保持一致,本文结合锁相环的原理,利用单片机实现高精度的数字锁相环。