New high voltage pulse generator for Type I wire wound winding of electrical machines

Abstract

The adoption of switching electronic converters for squirrel cage motor drives can lead to some critical issues during operation. Among the others, one of the most deeply investigated problems is the early failures of the stator winding insulation. When the motors are supplied by power electronic converters the stator insulation system is indeed subjected to some peculiar electrical stresses; the fast transients lead to an uneven distribution of potential along the windings and to the presence of over-voltages at the motor terminals when the connection cable between the converter and the machine is longer than few meters, usually ten or more. Since one of the parameters that has a major influence on such phenomena is the voltage rise time of the inverter output pulses, the stress for the insulation is enhanced by the adoption of ultra fast IGBT switching devices. The aim of this research activity is to realize a new high voltage pulse generator so that both the peak voltage of the generated pulses and their rise times can be varied in order to characterize Type I insulating systems of the electrical machines windings.