New Concept of the DC-DC Converter Circuit Applied for the Small Capacity Uninterruptible Power Supply

This paper discusses about a new concept of the DC-DC converter for the small capacity Uninterruptible Power Supply (UPS) systems. In the UPS system, the DC-DC converter is used to boost battery voltage up to the inverter's input voltage when UPS is operating in the backup mode. While the conventional small capacity UPS use the push-pull DC-DC converter which has low efficiency and high surge voltage, the new concept which uses the CLC Resonant Type Full-Bridge DC-DC converter is proposed. In this concept, the surge voltage of the main switches and the second-side rectifier diodes is reduced, which helps to improve the efficiency and allows using the low-voltage devices. In the experiment, the efficiency of the DC-AC conversion system which uses the CLC resonant type full-bridge DC-DC converter is measured. As a result, the max efficiency is about 90%, so the usability of the proposed CLC resonant type full-bridge DC-DC converter can be confirmed.