Estimation of model parameters for simulation of inverter-fed electrical machines’ transient terminal voltage

Abstract

This paper studies the voltage stress in machine windings of traction motors fed by voltage source inverters equipped with fast switching semiconductors like SiC-power MOSFET, resulting in steep-fronted inverter output voltages. The voltage stress of the insulation system is caused by different factors, e.g. voltage overshoot, non-linear voltage propagation or parasitic electrical components influencing the electrical voltage and current characteristics in the machine winding. The measured terminal voltage on the machine was simulated with a lumped model of the motor cable and a high-frequency model of the machine. With the simulation model the parameters were identified which have the highest influence on the machines voltage. The experimental results on a test bench are verified by a simulation model and the relevant parameters are determined for the measured voltage characteristics. The experimental validation of the model was conducted using a purpose-made traction machine with form-wound three-phase winding stator and a power rating up to 1.5 MW.