A model of semiconductor converter-fed asynchronous machines taking into account energy losses and thermal processes

A model of a semiconductor converter-fed dual-stator windings induction machine of the adjustable-speed propulsion drive is built up by decomposing the system into sub-circuits with lumped parameters which are coupled together by means of dependent voltage/current sources. Measurements of frequency responses of the driving point impedance of the stator windings have shown a strong impact of the skin effect on machine parameters. In the proposed model, electric and magnetic skin effects are reproduced by means of RL-ladder networks incorporated into the stator and rotor sub-circuits. A thermal model is described in terms of average temperatures and heat flows in the body of an induction machine. The paper concludes by examining the electromechanical and thermal responses of the motor energized by voltage sources of different waveforms.