Modified Sequence-Control Technique for Improving the Performance of Regenerative Bridge Converters

A modified sequence-control technique for series-connected regenerative bridge converters, for improving the performance at line and load terminals, is described. The reactive power is minimized by operating the fully controlled converters with the half-controlled characteristic, grading the input voltages to the bridge converters, and adopting the control strategies such that the converter with minimum input voltage operates over the full range of thyristor firing angles, whereas the firing angles of other converters are restricted to values corresponding to their ratings. Two control strategies are described. The comparative evaluation of the proposed technique with the existing techniques is also presented.