Eddy Current Losses in Soft Magnetic Materials

Abstract

Magnetic losses in static and rotating electrical machine cores, most commonly assembled from electrical steel strip or laminations, consume more than 5% of all the generated electrical energy. The origins of the losses and the merits and pitfalls of traditional approaches to separation into classical eddy current and hysteresis components are described. Physical and structural characteristics of nonoriented and grain‐oriented electrical steels that have the greatest influence on their losses are discussed. Limitations of present‐day approaches to measurement or computational analysis of flux distributions and losses in electrical machine cores are summarized prior to explaining the occurrence of additional eddy current losses due to practical factors, such as flux harmonics, mechanical stress, sheet edge burrs, and rotational magnetization occurring in core joints.

Graphite Felt-Sandwiched Ni/SiC Catalysts for the Induction Versus Joule-Heated Sabatier Reaction: Assessing the Catalyst Temperature at the Nanoscale

“…Assuming the methanation exothermicity as independent from the nature of the adopted heating setup, under IH, the electrically conductive and magnetic nickel deposits (catalyst active phase) undergo dedicated heating paths . In particular, eddy currents (or Foucault currents) , flowing through the larger metal aggregates and hysteresis loss , phenomena can induce local heating directly at the metallic phase. Hysteresis loss depends from the specific saturation magnetization ( M s ) of the metal particles.…”

“…d Specific saturation magnetization (M s ) determined for the different Ni particle sizes on the basis of eq 4 and assuming a mean NiO layer of 0.5 nm in accordance with the TEM analysis on the samples of this study. Foucault currents) 47,48 flowing through the larger metal aggregates and hysteresis loss 49,50 phenomena can induce local heating directly at the metallic phase. Hysteresis loss depends from the specific saturation magnetization (M s ) of the metal particles.…”

“…Assuming the methanation exothermicity as independent from the nature of the adopted heating setup, under IH the electrically conductive and magnetic nickel deposits (catalyst active phase) undergoes dedicated heating paths. 48 In particular eddy currents (or Foucault currents) [49][50] flowing through the larger metal aggregates and hysteresis loss [51][52] … where ρNi = 8.8 g cm -3 , ρNiO = 6.827 g cm -3 , σ s bulk = 57.50 emu g -1 , R = mean radius of Ni NPs from XRD analysis and r = (R -average thickness of NiO thin layer).…”

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

“…Eddy currents or Foucault currents are generated by an oscillating electromagnetic field that penetrates the resistance of a magnetically conducting receiver and releases energy through the Joule effect [ 21 – 22 ]. The heating power in eddy currents is directly correlated with the square of the applied frequency and field amplitude.…”

Induction Heating: An Enabling Technology for the Heat Management in Catalytic Processes

“…When a susceptor is immersed in an alternating magnetic field, rf energy is directly targeted to the material and locally transformed into heat with only minor energy losses due to convection, conduction, or thermal radiation. There are three main electromagnetic dissipation phenomena responsible for rf energy conversion into heat, whose occurrence depends on the susceptor nature: (1) the hysteresis heating in the case of ferromagnetic (FM) materials, cycling through their magnetic hysteresis loops, , (2) the magnetic field heating mechanism by relaxation losses ( Néel relaxation mechanism ) taking place in superparamagnetic (SPM) nanoparticles, , and (3) the Joule heating due to eddy currents , (or Foucault currents) occurring on electrically conductive samples.…”