Input switched high performance three phase Buck-Boost controlled rectifier

Input current and power factor improvement of single and three-phase rectifiers by switch mode regulators are usually achieved by switching the output of rectifiers. The output switching makes input current high frequency switched, which is filtered by a small filter to get low input current THD at near unity power factor. In this paper a three phase Buck-Boost rectifier is proposed which is regulated at the input side by a three phase bi-directional switch. Direct input current switching ensures current displacement with input voltage always in phase. The number of diodes to achieve bi-directional input switching and output stage of the three-phase buck-Boost circuit increases. Comparison is made between proposed and conventional circuit under same loads and operating conditions. Results show that the proposed circuit has better performance for variable loads at constant frequency switching. The effect of increasing the number of semiconductor components have not been investigated completely.