High-frequency isolation UPS with novel SMR

This paper concerns a newly developed 2 to 5 kVA, high-frequency isolation type UPS (uninterruptible power system). This UPS features a novel SMR (switch mode rectifier) that is applied to the input converter section and a newly developed low-loss IGBT (insulated gate bipolar transistor) that is employed in both inverter and converter sections. The SMR, as a single converter, has functions for high-frequency isolation, enhancement of input power factor and stabilization of DC output voltage. In the case of a new type of DC-clamped SMR (DCC-SMR), the number of current flowing devices in the frequency changer has been reduced to 1/2 of those compared with systems using a conventional SMR, and simplification of the snubber discharge circuit has also been achieved. Owing to the above, this newly developed UPS not only has small volume and weight, about 1/2 of that of commercial frequency isolation type UPSs, but also provides high efficiency-at least equivalent to that of the latter UPS