Iron loss modelling which includes the impact of punching, applied to high-efficiency induction machines

Within the market evolution towards higher efficiency machines, there is a need for more precise modelling tools, taking also higher frequency power supplies into account. This paper implements the effect of cut edge degradation, due to punching, on the local magnetization curve and local losses, aiming at improved calculation of magnetization current and machine iron losses. For an induction machine, defined by Leroy Somer and a high efficiency electrical steel, selected from ArcelorMittal´s range, this study combines advanced material characterization with improved modelling techniques, and is validated by selected machine testing procedures. For the sake of clear loss separation a machine with slotless rotor was characterized at two conditions regarding speed and excitation. The loss model, including already the effect of rotational losses and higher harmonics, was enhanced with the punching effect, which led to a model accuracy of 86% at synchronous speed when compared to the measured losses. This study also led to further insights in local magnetization behaviour, to be used in further design optimization.