Passive, microprocessor switch, and magnetic filters for power electronic drives

Multiple converter thyristor drives in a power system must generally satisfy standard G5/3. The authors discuss the problem in terms of a 7 drive system with each drive operating an identical time-displaced duty cycles. Four methods of passive or switch-filtering have been compared in the context of a 14 converter drive in a food-processing plant. Microprocessor switch-filtering has been shown to be very effective, but sensitive to system disturbances. Magnetic harmonic cancellation in double-dual-converter drives is to be preferred if the correct firing relationships can be maintained by the central microprocessor