Experimental Validation of Improved Power Quality in Unidirectional Multipulse AC - DC Converters due to Higher Pulse Number

Deployment of ac-dc converters invariably entails injection of current harmonics into the ac utility; and voltage ripple and hence, harmonics on the dc side. Multipulse unidirectional ac-dc converters are essentially rectifiers that have a high pulse number. The correlation of pulse number of an ac-dc converter and its power quality parameters on both the ac and dc sides is well established, however, in this paper the mathematical expressions of the instantaneous line current and load voltage and hence, their harmonic constituents, have been derived from the first principles for the most fundamental topologies and have been extrapolated to determine those of the higher pulse ones. This is important in the design of current harmonic and voltage ripple filters. Also, the correlation of pulse number with harmonic current distortion is theoretically established and experimentally validated with data from the three-, six- and twelve-pulse rectifiers.