Ys. Tzeng, HARMONIC-ANALYSIS OF PARALLEL-CONNECTED 12-PULSE UNCONTROLLED RECTIFIER WITHOUT AN INTERPHASE TRANSFORMER, IEE proceedings. Electric power applications, 145(3), 1998, pp. 253-260
The author presents a harmonic analysis of a parallel-connected 12-pul
se uncontrolled bridge rectifier without an interphase transformer (IP
T). Five normal operating modes of the specific rectifier circuit are
classified, using an analytical method by deriving instantaneous AC cu
rrent and DC voltage waveform equations. The discrete Fourier transfor
mation algorithm is then carried out to obtain both current and voltag
e harmonic contents. Both the AC current and DC voltage harmonics for
rectifiers with and without an IPT have been investigated to discuss t
he influence of the IPT on rectifier harmonics. Simulation results rev
eal that discrepancies in harmonic contents of both AC current and DC
voltage of the two rectifier circuits are marked. It is noted that, fo
r extremely light load up to rated load conditions, the total harmonic
distortion (THD) of line-supply current is reduced, while the THD of
DC output voltage is increased when the IPT is deleted from rectifier
circuit.