Comparison of active filtering with multipulse input current shaping techniques for AC-DC converters

AC-DC converters are used in a variety of power supply systems. The simple diode bridge rectifier realizes a six-pulse AC-DC converter circuit to feed R-L and R-C equivalent loads at its DC bus. However, the diode bridge rectifier suffers from the problem of current harmonics. There are two main stream techniques emerging that solve the problem of current harmonics. These are active current shaping and passive current shaping. The multipulse converters fall within the category of passive current shaping, and the active filter method falls within the category of active current shaping. The active current shaping methods also include a variety of boost AC-DC converters. This paper proposes a variety of multipulse current shaping methods followed by a detailed mathematical modeling of multipulse AC-DC converters. Performance of multipulse AC- DC converters is compared with that of active filter based current shaping.