C. Zöller, M. Vogelsberger, T. Wolbank:
"Inverter-fed Drive Stator Insulation Monitoring Based on Reflection Phenomena Stimulated by Voltage Step Excitation´";
Talk: IEEE International Energy Conversion Congress and Exposition (ECCE), Milwaukee, USA; 09-18-2016 - 09-22-2016.

Reflected wave transient phenomena in voltages and currents of inverter-fed drives caused by voltage source inverters (VSI) operating with pulse width modulation (PWM) with high dv/dt rates are well known and analyzed in many studies. The reflection phenomena occurring at the machine terminals, resulting in high overvoltages are one reason for the stress and aging mechanism of AC machines insulation system. The motivation of this work arises out of the need for a continuous monitoring of the insulation health state for traction drives systems in order to ensure high reliability of the drive over many years of operation. With a voltage step initiated by a switching transition, the inverter elicits a response in the drive system. By using the information of the resulting transient effects, conclusions can be drawn on basis of the oscillation behavior which are indicative for a change in the insulation system. Investigations in this work show that an alteration in the shape of the system transients, in peak

transient phenomena, inverter-fed drives, voltage source inverters

http://publik.tuwien.ac.at/files/publik_257096.pdf