1-D and 2-D Loss-Measuring Methods: Optimized Setup Design, Advanced Testing, and Results

Abstract

Accurate measurements of magnetic losses in laminations are a prerequisite for their theoretical assessment, as well as for satisfying calculations of energy dissipation in engineering systems. The standardized and universally applied measurement method, used as a reference for the definition of the material quality in the specification standards, is based on the Epstein test frame magnetizer. Its success relies on the reproducibility of the performed measurements. Its limitations come, on the one hand, from cumbersome sample preparation and, on the other hand, from a certain divergence of the measured loss figures from the true loss figures. Similar systematic differences between measured and true loss values are also observed with the standard Single Sheet Tester method. In both cases, measurements under bi-dimensional induction are or cannot be envisaged. The design of new measurement setups and magnetizers overcoming the drawbacks of the Epstein and Single Sheet Tester methods and possibly becoming recognized Standards in the future is welcome, but challenging. This paper is devoted to a comprehensive discussion of the state of the art in the alternating and two-dimensional measurements of energy losses in soft magnetic materials for electrical applications. We will summarize, in particular, measuring solutions proposed in the current literature and we will discuss in detail recent developments achieved in the authors' labs regarding 1D measurements with compensated permeameters and 2D measurements at high inductions and high frequencies.

Skin Effect and Losses in Soft Magnetic Sheets: From Low Inductions to Magnetic Saturation

“…To reach the kHz range at reasonably high Jp values (e.g. Jp > 1.0 T) a specific 2D magnetizer, based on digitally controlled threephase supply and wattmetric setup was developed, as discussed in detail in [49]. The interest in the response to rotational fields of low-carbon steels brought at high induction values relates to their still pervasive applications in rotating machines.…”

A new hysteresis simulation method for interpreting the magnetic properties of non-oriented electrical steels

“…During the measurement, the magnetic field 𝐻(𝑡) is generated by the input electrical current 𝑖(𝑡) of the primary winding. Meanwhile, the waveform of the secondary induced voltage for sinusoidal excitation is maintained as sinusoidal as possible, achieved using a PID feedback controller [24]. Then, the magnetic flux densities 𝐵(𝑡) are derived according to Faraday's law and Lenz's law.…”

Influence of the geometric parameters of a vertical rotational single-sheet tester on sample field homogeneity

“…First, its ease of implementation due to similarities to the standardized SST. Second, a better homogeneity of H and B in the middle of the test sample (de la Barriere et al, 2018). Third, it allows to reach higher flux density levels in the test sample than the horizontal SST (Fonteyn and Belahcen, 2008;Miyagi et al, 2009).…”

“…From the 80s, numerous works have been done on the subject, and several two-dimensional characterization devices can be found in the literature (de la Barriere et al , 2018), each one having its pros and cons. An unfortunate consequence of that large variety of devices, in terms of topologies and geometries, is that it is difficult to set a standard, such as those that exist for the single-sheet tester (SST) (IEC, 1992) or the Epstein frame (IEC, 2008).…”