Review of Energizing High Power Medium Voltage AC Drives

This paper first introduces the well known high power medium voltage AC drive topologies. Starting with types using a capacitive DC link voltage source inverter fed from a drive isolation transformer and multi-pulse rectifier the many approaches of initial energization techniques are summarized. Therewith, a common knowledge basis is established and the adverse reactions of direct on line energizing at full-voltage are exemplified in regards to the magnetic and DC link capacitive inrush. Based on that, the energizing of a three-level neutral point clamped topology using a soft-magnetization technique that mitigates the aforementioned stresses on the equipment is presented.