Determination of Core Losses Using an Inverse Modeling Technique

Abstract

This paper presents an inverse thermal modeling technique to determine the core losses from the temperature rise inside the transformer core. For this purpose, initially, a customized printed circuit board (PCB) with thermal sensors is used to measure the temperature rise. Afterward, a 3D magnetothermal forward model is developed to validate the temperature rise. The accuracy of the forward model is checked by comparing the simulated core losses and temperature rise of the transformer with experimental measurements for different supply conditions. The results show that the forward model can accurately estimate the core losses with a maximum relative error of less than 2.7% and predict the temperature rise in the core with a maximum relative error of less than 6.2%. Lastly, after ensuring the accuracy of the forward model, an inverse modeling technique is applied to the 3D thermal model to predict the core losses of the transformer directly from the measured temperature rise. The accuracy of the inverse model in estimating the core losses is checked by comparing the results with experimental measurements. The novel approach for the PCB design besides the inverse model shows that the technique can be applied to estimate the core losses directly from the measured temperature rise inside the core with a relative error of 2.7% compared to experiments.

Core loss determination in electric machines using short‐time transient thermal measurements

“…The modelling principle is similar to the presented thermal model for a transformer geometry in ref. [31], which is based on the following heat diffusion equation:…”

“…In a previous study [31], a novel customised sensor board embedded with PT100 thermal sensors is used for the temperature rise measurements in a transformer. This reduced contact noise and increased measurement accuracy.…”

A Non-Invasive Methodology for Magnetic Characterization of Transformers and Reactors

“…In this case, the total flux is present in the magnetic core and only the magnetizing current flux is present in the primary windings. The total core losses can be separated into hysteresis losses W h , eddy current losses W f , and excess losses W e [23]- [25].…”

The Modeling and Simplification of a Thermal Model of a Planar Transformer Based on Internal Power Loss

“…As described in [11], a new SPICE ferroelectric-thermal model of ferromagnetic core is given, and the calculation methods for the relevant magnetic parameters, geometric parameters, and thermal parameters are introduced. On this basis, an inverse thermal model based on the temperature rise of the transformer core is proposed to determine core loss [12]. For this purpose, PCB with thermal sensors is initially used to measure temperature rises, whereas these models in [10][11][12] lack comprehensive comparison, and different winding structures will lead to different power loss distributions inside.…”

“…On this basis, an inverse thermal model based on the temperature rise of the transformer core is proposed to determine core loss [12]. For this purpose, PCB with thermal sensors is initially used to measure temperature rises, whereas these models in [10][11][12] lack comprehensive comparison, and different winding structures will lead to different power loss distributions inside. In order to predict the temperature distribution of each component and provide the basis for high reliability, the thermal network modeling of planar transformers is essential [13].…”