An Uninterruptible Power Supply and Its Output Voltage Stability Control Method

To address the issues of low capacity and unstable output voltage in existing Uninterruptible Power Supply (UPS) systems, a phase control method for UPS output voltage with a bypass mode is proposed. A grid-following-like control strategy (input voltage feedforward control) is adopted when the UPS operates in bypass or normal mode, while a grid-forming-like control strategy (output voltage phase-locked control) is used during input voltage fluctuations or interruptions, thereby stabilizing the output voltage of various operating conditions of the UPS.