Magnetic core effects on the high-frequency behavior of transformers

Journal Article (2024)
Author(s)

Farzad Nasirpour (TU Delft - Intelligent Electrical Power Grids)

Mohamad Ghaffarian Niasar (TU Delft - High Voltage Technology Group)

Marjan Popov (TU Delft - Intelligent Electrical Power Grids)

DOI related publication
https://doi.org/10.1016/j.ijepes.2024.110035 Final published version
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Publication Year
2024
Language
English
Volume number
159
Article number
110035
Downloads counter
139
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Abstract

This paper investigates the high-frequency transformer losses attributed to eddy currents in both conductors and the core. A comprehensive model of a transformer winding is presented, meticulously incorporating skin and proximity effects. The winding resistance increase due to these effects is determined by applying analytical and finite element methods. The investigation highlights that eddy current losses in the magnetic core notably increase the resistance of each winding section in low frequencies. However, the impact of these losses diminishes as the winding length approaches the voltage wavelength at high frequencies. Consequently, the net magnetomotive force and flux in the core become negligible. As a result, the high-frequency impedance characteristics are remarkably similar for windings with and without a magnetic core. These findings are substantiated through rigorous simulations and empirical measurements.