Harmonics Phase Shifter for a Three-Phase System with Voltage Control by Integral-Cycle Triggering Mode of Thyristors
I. Badran, A.L. Mahmood and M.T. Lazim
DOI : 10.3844/ajassp.2008.1580.1587
American Journal of Applied Sciences
Volume 5, Issue 11
In integral-cycle triggering mode of voltage control, subharmonic as well as higher order harmonic components are generated in the load voltage waveforms of a three-phase system. These harmonic components are found to be unbalanced in phase displacement. The correction of the unbalanced phase displacement angles of a particular subharmonic or higher order harmonic for this type of triggering is investigated to solve the limitation of use of this important type of control as a drive and many other industrial applications. In this research a new phase shifting technique is proposed to correct the unbalanced phase displacement angles in the three-phase system. This technique depends on shifting the waveforms of either phase B or phase C or both by multiples of 2π. A microprocessor-based harmonic phase shifter is designed and tested with three-phase resistive and induction motor loads. It is found that there is a well agreement between the theoretical and experimental results and it is believed that the major problem of harmonics phase unbalances associated with the integral-cycle triggering mode of thyristors when used with three-phase circuits have been solved in the present research.
© 2008 I. Badran, A.L. Mahmood and M.T. Lazim. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.