New technique to improve the efficiency of Uninterruptible Power Supply

Uninterruptible Power Supply (UPS) equipments are used for various mission-critical systems, and the importance of UPS has increased due to the growth of IT market. Many systems are connected each other in the world, and so the systems have to work 7 days 24 hours. Power failure of one system might affect many other systems. Many kinds of circuit have been proposed and adopted for UPS equipments. For important systems such as data center server facilities, double conversion UPS are used to offer the highest reliability of power supply. Recently the environmental protection has become much important and it is required to reduce power loss for all electrical equipments. This paper explains new control method to obtain the high efficiency double conversion UPS using conventional isolation type main circuit, and introduces the related test results.