Correlation of line current distortion, DC voltage ripple frequency and pulse number in six-pulse bridges cascaded multipulse rectifier topologies

The pulse number which is the number of dc voltage pulsations corresponding to a time period of the input ac voltage is an important parameter of any rectifier topology. There is a definite correlation of the pulse number with the line current distortion and dc voltage ripple. Line current distortion is quantified by various parameters including total harmonic distortion (THD), distortion factor (DF), and total demand distortion (TDD) while the DC voltage ripple is quantified by parameters such as ripple frequency, ripple factor, etc. Multipulse rectifier topologies that provide dc voltage with a higher pulse number are regarded as improved power quality ac-dc converters (IPQC) because their ac utility line currents have low distortion levels compliant with contemporary power quality standards. The multipulse IPQC´s yield dc voltages with high frequency ripple with low ripple factor, thus, facilitating simple, compact and economical DC filters. This paper uses MATLAB to validate the correlation of the pulse number with the various rectifier parameters such as THD, DF, TDD, ripple factor etc.