Practical Aspects of Instantaneous Magnetization Power Functions of Silicon Iron Laminations

Abstract

Magnetic energy loss P of SiFe steel represents a key factor for the efficiency of soft magnetic machine cores. Traditionally, they are operated with 50 Hz (or 60 Hz), a frequency value that yields rather balanced portions of hysteresis loss and eddy current loss. In equivalent circuits of transformers, P tends to be represented by a magnetic power resistance RM, as a constant. For the most important case of sinusoidal induction B of 50 Hz, this would correspond to an instantaneous magnetization power function p(t) that is sinusoidal as well, however, with 100 Hz (or 120 Hz). On the other hand, from complex, non-linear mechanisms of hysteresis, it is obvious that p(t) should be strongly non-sinusoidal, even for exactly sinusoidal B(t). So far, almost all corresponding instantaneous investigations were restricted to calculated modelling of loss portions and transient modelling. On the other hand, for the first time, the present study was focussed on functions p(t) as measured at IEC-standardized samples of industrially relevant steel. Practical evaluations are discussed with respect to the revealed “history” of magnetization processes, as well as for product characterization. For these tasks, a novel digitized “Low-mass Single Sheet Tester” was developed that was applied for both non-oriented steel (NO) and grain-oriented steel (GO), for 50 Hz. Interpretations proved to be favoured by relating p(t) to total P, according to an instantaneous power ratio. As a result, both steel types revealed strongly non-sinusoidal power functions, with short durations of negative p. Negative p proved to be most pronounced for NO steel, as a measure for the onset of reversible turns of atomic moments. As a consequence, p(t) comprises strong upper harmonics of 200 Hz and even 300 Hz. Based on theoretical considerations, we split p(t) in a dissipative loss power function pL(t) and in a potential energy power function pP(t). Finally, we used p(t) to determine the corresponding power resistance RM(t) that proves to be a distinctly nonlinear function as well. It resembles a rectified co-sinus, also exhibiting short negative spikes that reflect the crystallographic dis-orientation of the polycrystalline material.

A Methodology for Calculating the R-L Parameters of a Nonlinear Hysteretic Inductor Model in the Time Domain

“…Instantaneous powers in the circuit are determined upon the identification of circuit parameters, as shown in Figure 2. The instantaneous power of a hysteretic inductor has also been recognised as an important subject in a number of recent research papers [5,6,17,[19][20][21]. Bramerdorfer et al carried out a comprehensive review of state-of-the-art methods for the characterisation of The instantaneous power of a hysteretic inductor has also been recognised as an important subject in a number of recent research papers [5,6,17,[19][20][21].…”

“…The instantaneous power of a hysteretic inductor has also been recognised as an important subject in a number of recent research papers [5,6,17,[19][20][21]. Bramerdorfer et al carried out a comprehensive review of state-of-the-art methods for the characterisation of The instantaneous power of a hysteretic inductor has also been recognised as an important subject in a number of recent research papers [5,6,17,[19][20][21]. Bramerdorfer et al carried out a comprehensive review of state-of-the-art methods for the characterisation of soft magnetic materials used in the magnetic circuits of electric machines [5].…”

New characteristic parameter of energy loss in permalloy

“…The two properties determine the energy conversion efficiency of SMMs within working frequency. As a result, metallic SMMs with high storage and loss of energy such as Si steel [12,13], are widely used in the Hz range, while metallic soft magnetic composites [14][15][16] and amorphous nanocrystals [17] can be used in the kHz range. With the development of sustainable and electrified world, none of SMMs can release full potential of efficient power conversion based on wide bandgap semiconductors [18,19].…”