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Energy harvesting devices (EHD) utilize small-scale components with low power losses. Key parts, the electric power transformers (EPTs) are to convert the voltage/current electromagnetic parameters from the primary, energy harvesting stage, to the secondary, storage and delivery power levels. Magnetic colloidal nanofluids seem to be a sound solution for building the magnetic circuit of such EPTs, enabling miniaturized constructions, whose implementation may benefit of LIGA fabrication technology. Because the magnetic cores of EPTs are, at least in part, fluid, the occurring magnetization body forces may result in complex flows that need to be known. Along this line, this paper presents mathematical models and numerical simulation results for a miniature, planar, spiral EPT with hybrid, ferrite-magnetic nanofluid core. Several electric powering schemes are envisaged and the pending flows investigated.

Energy harvesting devices (EHD) utilize small-scale components with low power losses. Key parts, the electric power transformers (EPTs) are to convert the voltage/current electromagnetic parameters from the primary, energy harvesting stage, to the secondary, storage and delivery power levels. Magnetic colloidal nanofluids seem to be a sound solution for building the magnetic circuit of such EPTs, enabling miniaturized constructions, whose implementation may benefit of LIGA fabrication technology. Because the magnetic cores of EPTs are, at least in part, fluid, the occurring magnetization body forces may result in complex flows that need to be known. Along this line, this paper presents mathematical models and numerical simulation results for a miniature, planar, spiral EPT with hybrid, ferrite-magnetic nanofluid core. Several electric powering schemes are envisaged and the pending flows investigated. [ABSTRACT FROM AUTHOR]

A new approach is presented in order to determine copper losses from measurements or simulations of planar inductors. Copper losses are modelled with a series resistance r(f) that depends on the frequency. Measured or simulated admittances of the inductors are used to determine the model parameters of the inductors. The resistance r(f) is determined in three frequency domains: (i) at very low frequencies (or DC); (ii) at low frequencies (capacitive couplings are negligible); (iii) at resonant frequencies, i.e. high frequencies. The presented approach is different as those encountered in literature and allows the series resistance from measured or simulated Sij parameters to be determined. [ABSTRACT FROM AUTHOR]