Multi-Parallel Asymmetrical Cycloconverter Having Improved Power Factor and Waveforms

A newly developed cycloconverter having improved power factor is presented. The cycloconverter is composed of three or six converters connected in parallel through interphase reactors. To reduce reactive power, the thyristors in the bridge are controlled to have the minimum number of phase controlled thyristors and the other thyristors are kept the states turn-on or off. To compensate the unbalance input current of the bridge, the input terminals of three or six bridges are parallel connected and twisted each other. Owing to multi-parallel configuration, the cycloconverter fits for relatively low voltage and high current rating. The method enables to realize almost the same power factor and harmonic contents as the conventional high performance cycloconverters. Both of the experimental and simulation results show that the power factor of above 0.8 is obtained in 70% of its operating area at load power factor 0.8. Besides this paper describes the microcomputer based gate control circuit and compared results with the conventional cycloconverters.