Optimization of Current Total Harmonic Distortion in Series-Connected Rectifiers

Abstract

An innovative method for reducing current total

harmonic distortion on the AC side of twelve-pulse series

connected AC/DC rectifiers is simulated in this paper. The

principle of the method is to modify the current waveforms on

the DC side of the converter by using self-commutated

switches. An averaging inductor is added to the series

connected converters and thus simplifies the pulse

multiplication significantly. This method can make a 12-pulse

double bridge converter to operate at 24, 36 and 48 pulses. A

reinjection transformer is also used in series-connected

converters to reinject a current to the main rectifier.

Minimum value for the total harmonic distortion of AC

current can be achieved by selecting an appropriate value for

turn ratio of reinjection transformer. Genetic Algorithm (GA)

has been used to calculate the optimal value for turn ratio of

reinjection transformer. The total harmonic distortion of AC

current has been calculated for different values of the turn

ratio of reinjection transformer, and the minimum value of

THD is obtained at turn ratio of reinjection transformer

calculated by GA for 24, 36 and 48-pulse operation modes.