Harmonic reduction in d.c.-ripple reinjection

A d.c.- ripple reinjection principle is described which reduces the harmonic content produced by static convertors. It is shown by theory and experiment that, using this principle, a six-pulse convertor configuration can be made to operate as a twelve-pulse convertor from the point of view of a.c. and d.c. system harmonics. The reinjection circuit includes a feedback convertor in series with the d.c. output. This convertor provides automatic adjustment of the reinjected current as the load changes and improves the efficiency of the overall system.