In the highly emulative UPS market, every renowned UPS manufacturer is trying to ameliorate their UPS performance and reliability steadily. This increasing demand will only be satisfied if the components used can keep pace. IGBTs are considered as one of the best choices for medium and high-power UPS because of their simple control, great switching characteristics and excellent reliability. Especially in terms of efficiency, acoustic noise, size and weight, they remarkably uplift UPS performance. In high power UPS where the inverter operates between 2 and 4 kHz, the main benefit of the IGBT is simplification of transistor control (increased reliability). Its efficiency is equal to that of bipolar transistors. In medium power UPS often installed in computer rooms, the acoustic noise criterion makes it necessary to remove the 50 or 60 Hz transformer and to add an inverter operating at a frequency of 16 kHz, thus making the IGBT absolutely indispensable both due to the lessening in number of components required to control it and due to the gain in weight and in total dimensions. Production of new products calls for a prudent, meticulous choice of new components. We are frequently informed about the announcements of new elements as the IGBT is still in the growth stage. Present studies should not be questioned as authorized approval of a power semiconductor is long and expensive.