Uninterruptible power supply for the back up of ac-power supply

The present invention relates to an uninterruptible power supply to an apparatus, and more particularly, to uninterruptible power supply of AC power backup system using an electric double layer capacitor as an energy storage element device. The uninterruptible power supply according to the present invention is a direct current from the switch to the direct current and stored in this energy storage device, and the power is interrupted or when the instability of the power of the energy storage device by using the AC / DC converter to the AC input from the AC power source in the input to an uninterruptible power supply of AC power backup system device provided to the output load by switching to the exchange by using a DC / AC inverter, and the energy storage element is electric double-layer capacitor, the charging voltage of the electric double-layer capacitor and the DC / It characterized by setting the ratio of the minimum driving voltage of the AC inverter to 1.3 times or more. The uninterruptible power supply is capable of performing energy efficiency and power backup time is significantly increased by the same power source into a direct current compensation is less than the power backup system energy.