Application of 12-pulse converters to reduce electrical interference and audible noise from DC motor drives

Typical drives, which utilize six-pulse bridge converters or six-pulse four-quadrant dual converters, produce commutation notches in the line voltages, harmonic line currents of fifth, seventh, etc. order, and 360 Hz armature-current ripple. Technical and cost comparisons are made between six-pulse drives with AC and DC side filters and 12-pulse drives that reduce both electrical and audible noise. A 12-pulse midpoint converter using thyristor armature reversing switches for four-quadrant elevator drive services is described, and construction and harmonic measurements are reported