中文摘要：

UPS逆变输出与电网同步性是衡量UPS的一个重要指标。探讨一种UPS逆变输出相位反馈控制策略。通过软件锁相获取电网相位，作为逆变输出相位基准，再经反馈控制使逆变输出相位精确跟踪基准相位。在理论分析基础上设计了逆变器输出相位反馈控制的补偿网络，并在三电平UPS逆变器平台上对该控制方法进行验证，结果表明该方法能够实现逆变输出与电网同步。

英文摘要：

The synchronization of the UPS output and the grid is an important indicator to measure the UPS. An UPS inverter output phase feedback control strategy was studied, which could obtain the grid phase by software phase-locked loop to become the phase reference of the inverter output phase. Then the feedback control was used so that the inverter output phase could track the reference phase precisely. Based on theoretical analysis, a compensation network of output phase feedback control was designed. The control method was verified on the three-level UPS inverter platform, the experimental results show that the inverter output is able to synchronize with the grid through this method.