High frequency extension of non‐linear models of laminated cores

Abstract

Purpose -The paper gives a new measurement method of the parameters characterising the magnetic laminations for broadband low-level signals defined at any operational point. Design/methodology/approach -High frequency phenomena machines fed by PWM inverters are related to low-level signals corresponding to minor hysteresis loops around the instantaneous working point, which moves on the main loop at the basic frequency. The minor loops are assimilated to ellipses, which are characterised by only two parameters: the incremental magnetic permeability (m) and the electric conductivity (s).Findings -For small signals high frequency field components, the laminated steel behaviour can be described by two local parameters (m, s) and skin effect. The values of m and s do not depend on frequency up to 1 MHz, but only on the operating point.Research limitations/implications -The proposed broadband characterisation should be associated with a Priesach model that defines the operating point for computer simulation of high frequency phenomena. Practical implications -The broadband characterisation of magnetic laminations is useful for studying the behaviour of the windings of the PWM-fed machines. Originality/value -Broadband measurements are now possible on small magnetic steel lamination samples.

High-Frequency Characterization of Losses in Fully Assembled Stators of Slotless PM Motors

“…The same approach has also gained recognition when applied in the frequency domain [36], [55]. For small perturbations around a magnetic working point, core permeance in the frequency domain is characterized by the complex relative permeability µ r,e [48], [56] according to:…”

“…In this paper, the theory from [56] is combined with static 2D FEA to determine the harmonic magnetic flux density distributions in the stator iron and windings. The corresponding losses can subsequently be identified.…”

Construction of transformer core model for frequency response analysis with genetic Algorithm

“…In practice, the parameters of core lamination, such as local magnetic permeability μ r and the conductivity of the core lamination σ, are usually determined by a number of experimental tests using a lamination sample [5], [6]. However, in many occasions such tests can not be applied due to the unavailability of the lamination samples.…”

“…2. Since the complex reluctance R of each core section takes into account the eddy currents effect due to complex magnetic permeabilitŷ μ eff (equation (1)) [8], it is represented by a corresponding impedance Z in the equivalent electrical circuit in the form of an inductance L and a resistance R to reflect eddy-current losses in the core as follows [5], [6]:…”

“…permeability and eddy-current losses [5], [6]. Recently, evolutionary algorithms such as genetic algorithms (GAs) [7], were utilized to identify model parameters using limited measurement data, that offer a way to overcome such difficulties.…”