| Abstract |
Single-phase, low power Static Uninterruptible Power Supplies (SUPS) based on the Parallel design concept have been known for some years. However, at ratings above 10 kVA, three-phase systems based on a Series design are almost universally used. Despite its common usage, the Series SUPS has a number of disadvantages which may be effectively overcome by the application of the Parallel design concept. This mode of operation allows the inverter to run lightly loaded even when the SUPS itself is supplying its full rated output. In addition, the input rectifier required by the Series type is eliminated, leading to increased efficiency and virtually no input voltage distortion. A method of applying the Parallel concept to the design of higher power (220 kVA) three-phase SUP's, offering the advantages mentioned above, is presented. |
