Smart uninterruptible power supply capable of high efficiency operation and method of controlling uninterruptible power supply

PURPOSE: An intelligent uninterruptible power supply operating with high efficiency and a controlling method thereof are provided to obtain a sufficient reserve rate of input power by estimating the optimum operation condition in the given environment. CONSTITUTION: A PWM rectifier(31) converts an AC voltage from a system into a DC voltage. An inverter(35) converts the DC voltage from the PWM rectifier and a battery into the AC voltage and supplies the AC voltage to a load. A bypass switch(34) operates when system power is directly supplied to the load. A controller(37) receives an input voltage, input power, and a load amount and controls the operations of the bypass switch and the inverter. The controller includes a measuring unit(40), a data storage unit(38), and a control unit(39). [Reference numerals] (30) System; (31) PWM rectifier; (32) Battery charging and discharging unit; (34) Bypass switch; (35) Inverter; (36) Load; (38) Data storage unit; (39) Control unit; (40) Measuring unit; (AA) Controller