Transient magnetic modeling and measurements of sensorless controlled induction machines

For the design of modern standard AC machines, it is sufficient to consider only the fundamental wave behavior of the machine. This is usually achieved by means of standard calculation programs and, in some cases, even finite-element calculation. However, in some applications such as high speed drives, or speed sensorless drives, both the transient electrical behavior of the machine as well as the transient magnetic behavior (including hysteresis of the lamination) are important and, thus, have to be taken into account in the design process of the machine. On modern computers, finite-element calculation would take an extensive amount of calculation time even if only the transient electrical behavior is considered. The only acceptable way is, thus, to combine a transient magnetic simulation with an electrical model of the machine. One important fact is that this combination is the estimation of the different electrical, mechanical, and magnetic parameters of the resulting simulation model. In this paper, a combined transient electrical and magnetic model of an induction machine is shown, and the determination of the different model parameters from measurable parameters of the lamination material, as well as the geometry of the lamination and winding scheme, is presented. Thus, it is possible to cover even transient hysteresis effects in inverter fed machines.