In integral-cycle triggering mode of voltage control, subharmonics and higher order harmonic components are generated in the three phases 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 the integral - cycle triggering mode of control is investigated to solve the limitation of use of this important type of control as a drive and many other industrial applications. Three phase shifting techniques were proposed in this work to correct unbalanced phase displacement angles produced in a three - phase system with voltage control by integral - cycle triggering. The first technique depends on using combination of the integral - cycle and phase - angle triggering modes of control. The second one depends on shifting the waveforms of either phase B or phase C or both by multiples of 2л. The third technique uses a combination of the two techniques. Theoretical and practical investigations reveal that when the first and third techniques are used to correct the unbalanced phase displacement angles, the harmonic amplitude spectrum is highly distorted. However, only the use of second technique causes a balance in both phases and amplitude. Therefore, it was implemented practically using a microprocessor - based system.. A prototype harmonic phase corrector system is designed and built in the laboratory. The system is tested with three - phase resistive and induction motor loads. The design of the circuit is simple, inexpensive, and can be assembled easily using commercially available components. It is found that there is a well agreement between the theoretical and experimental results and it is believed that the major problems associated with the integral - cycle triggering mode with three - phase circuits have been solved in the present work.