Modeling of Transient Overvoltages in Inverter-fed Machines with Hairpin Winding

Abstract

The voltage stress of inverter-fed electrical machines increases when fast-switching wide-bandgap semiconductors are used. For the design of reliable electrical machines, it is therefore becoming increasingly important to analyze these voltage stresses in the winding system in more detail in order to design a correspondingly robust insulation system that can withstand the stresses. Of high importance is the modeling of transient overvoltages, which can be many times the DC link voltage and are a common cause of partial discharges that damage the insulation system of electrical machines. Since in hairpin windings the position of each conductor is known special precautions can be taken to prevent transient overvoltages. In this paper, a universally valid and automatable methodology is presented to model the voltage distribution in hairpin windings and identify transient overvoltages.