Power-saving line interactive uninterruptible power system

A power-saving line interactive UPS has a power switch set (10), a low-frequency transformer (11), a full-bridge switching circuit (12), a main controller (13), a charge and discharge mode controller (14), a rechargeable battery (15) and a high-frequency charging circuit (16). The high-frequency circuit is connected between an AC power input terminal and the rechargeable battery (15) to convert the AC power into a DC power and charge the rechargeable battery (15). Therefore, when the AC power is normally supplied and the power capacity of the rechargeable battery (15) is not full, the high-frequency charging circuit (16) is activated to charge the rechargeable battery (15) without charging the rechargeable battery (15) through the low-frequency transformer (11) and the full-bridge switching circuit (12), thereby effectively reducing overall power consumption.