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

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.