On the Parallel Operations of Triport UPS Systems

Operations of parallel-connected Triport UPS systems are discussed. The parallel operation becomes important (1) for increasing the rated kVA of the system and (2) for realizing a redundant system to improve the system reliability. In this paper, we consider the typical parallel operation of two Triports under the normal mode and analyze the current balance conditions which make the ratio of output currents equal to that of the kVA ratings. Experimental results are shown about the current sharing characteristics at steady state, the output voltage transient characteristics for load current variation and so forth.