Power Factor Improvement with a Modified Phase-Controlled Converter

A modified phase-commutated converter with an improved power factor (PF) is presented and is analyzed for both rectifying and inverting modes. The optimal power factor firing control is formulated while taking into account commutation overlaps. Different modes of converter operation are identified and are analyzed in terms of reactive power requirements, power factor, and harmonic distortion on both ac and dc sides. The results are used to compare critically the new converter with a conventional six-pulse bridge.