Stochastic Modeling of Soft Magnetic Properties of Electrical Steels: Application to Stators of Electrical Machines

Abstract

To take account of the uncertainties introduced on the soft magnetic materials properties (magnetic behavior law, iron losses) during the manufacturing process, the present work deals with the stochastic modeling of the magnetic behavior law B-H and iron losses of claw pole stator generator. Twenty eight (28) samples of slinky stator (SS) coming from the same production chain have been investigated. The used approaches are similar to those used in mechanics. The accuracy of existing anhysteretic models has been tested first using cross validation techniques. The well known iron loss separation model has been implemented to take into account the variability of the losses. Then, the Multivariate Gaussian distribution is chosen to model the variability and dependencies between identified parameters, for both behavior law and iron loss models. The developed stochastic models allow predicting a 98% confidence interval for the considered samples.

Uncertainty propagation of iron loss from characterization measurements to computation of electrical machines

“…In both cases, 10% variation of the quantities is taken as uncertainty range. The first approach thus describes the propagation of uncertainties from the parameters of the model to the computed losses through the FE simulation and loss model, whereas the second approach describes this propagation from measurements to computations as described in (Ramarotafika et al 2012). The uncertainty itself is quantified using the Sobol indices (Sobol 1993) and the stochastic sensitivity analysis.…”

Identification of Synchronous Machine Magnetization Characteristics From Calorimetric Core-Loss and No-Load Curve Measurements

“…Both [3] and [4] approached the problem in a forward manner, meaning that the experimentally or analytically determined degraded material properties were input to finiteelement (FE) models as parameters, and the core losses were obtained as the outputs from the models. On the contrary, a stochastic approach was presented in [5], in which probabilistic models were developed for the magnetization curves and iron-loss coefficients of a stator core material by utilizing experimental data from 28 stators.…”

Estimation of additional losses due to random contacts at the edges of stator of an electrical machine

“…The burrs formed at the edges of the sheets are random in nature and introduce uncertainties in the solution. There are studies done in (Ramarotafika, et al, 2012) where uncertainties due to measurement in permeabilities are considered. The interlaminar resistance distribution due to punching is discussed in (Schmidt & Beiler, 1947) which states that losses due to interlaminar currents are no more than one percent of the total core loss.…”