Harmonic Phase Shifter for Discrete Amplitude Modulation Technique

Abstract

In discrete amplitude modulation orintegral-cycle control, subharmonic and higherorder harmonic components are generated inthe three phases of a three phase system.These harmonic components are found to beunbalanced in phase displacement. Thecorrection of the unbalanced phasedisplacement angles of a particularsubharmonic or higher order harmonic for thistype of triggering is investigated to solve thelimitation of use of this important type ofcontrol as a drive and many other industrialapplications. The multiple of 2 phase shiftingtechnique is used to correct unbalanced phasedisplacement angles produced in a three-phasesystem. A computer-based harmonic phasecorrector is designed and tested with threephaseresistive and induction motor loads. It isfound that there is a well agreement betweenthe theoretical and experimental results and itis believed that the major problems associatedwith the integral-cycle triggering mode withthree-phase circuits have been solved in thepresent work.