Influence of cable parameters on the inverter fed electrical machines transient terminal voltage

Abstract

Fast switching semiconductors are responsible for additional voltage stress onto machine winding insulations. As this may lead to an insulation breakdown and downtime of the drive, researchers worldwide have been investigating the effects leading to this overvoltage for many years already. Appropriate countermeasures should eventually avoid the insulation deterioration and drive outage. This paper studies the voltage stress in machines winding insulation affected from fast switching semiconductor (e.g. SiC) supply. It compares the measurements of the machine winding terminal voltage obtained when supplied with two different sets of cables, each 10m long, with different electrical parameters. Especially the amplitude of the machine terminal voltage turns out to be significantly different as well. This paper aims to verify these results and to explore which cable parameters have the highest influence on the machines voltage. The electrical parameters of the cables and the machine are estimated from measurements and used in a lumped-circuit model for the cables and the machine. The simulation results are then presented, and it is tried to explain the measured effects on the machine terminal voltage.