Coupled Finite Element and Micromagnetic Modeling of Iron Losses in Tape Wound Magnetic Cores
Paakkunainen, Elias (2022)
Paakkunainen, Elias
2022
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2022-03-22
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202203142519
https://urn.fi/URN:NBN:fi:tuni-202203142519
Tiivistelmä
A new model is developed to predict iron losses in tape wound magnetic cores. The model aims to accurately predict the losses at high excitation frequencies and take into account the geometry of tape wound cores better than already existing methods. There is a demand for accurate models of magnetic components at high frequencies, for example, due to the development of power electronics towards higher switching frequencies. The increased complexity of the developed model is expected to lead to longer simulation times.
Three different methods are utilized to study relevant phenomena. These include the models developed in this thesis: the 1D micromagnetic model with eddy currents (1DMMEC) and the coupled 1D micromagnetic -- 2D FE model (1DMMEC--2DFE). Additionally, 3D micromagnetic simulations with MuMax3 are carried out. The iron losses are determined with all of these methods. Suitable numerical implementation of micromagnetic theory is also chosen. The 1DMMEC model introduces an approach where the tape material is modeled with micromagnetic theory, and the solution of the eddy current problem is approximated using a cosine series. The input to the model is the magnetic flux density, and the model is derived for a single strip of tape. The 1DMMEC--2DFE model is derived to consider better the cross-section geometry of tape wound cores. The model couples the 1DMMEC model to a 2D FEM formulation. The resulting model allows expanding the micromagnetic description of the tape material over the cross-section of tape wound cores.
The 3D micromagnetic simulations with MuMax3 cannot accurately model the iron losses. Direct simulation of the tape is not possible due to the computational burden, and small-scale simulations do not give satisfactory results. However, some magnetization processes in the tape can be examined through 3D micromagnetic simulations. The iron losses predicted with the 1DMMEC model are in good agreement with similar models from the literature. This motivates to attempt to couple the model with the 2D FEM to obtain a more general description of tape wound cores. The iron losses predicted with the 1DMMEC--2DFE model achieve good agreement with measured losses. In some situations, the predicted losses describe the measurements more accurately than the 1DMMEC model. The accuracy of the prediction seems to decrease slightly with thinner tape thicknesses. On the other hand, the simulation parameters were not varied to achieve the best fit to the measured losses in every situation. The computational burden of the 1DMMEC--2DFE model is significant with small excitation frequencies.
Three different methods are utilized to study relevant phenomena. These include the models developed in this thesis: the 1D micromagnetic model with eddy currents (1DMMEC) and the coupled 1D micromagnetic -- 2D FE model (1DMMEC--2DFE). Additionally, 3D micromagnetic simulations with MuMax3 are carried out. The iron losses are determined with all of these methods. Suitable numerical implementation of micromagnetic theory is also chosen. The 1DMMEC model introduces an approach where the tape material is modeled with micromagnetic theory, and the solution of the eddy current problem is approximated using a cosine series. The input to the model is the magnetic flux density, and the model is derived for a single strip of tape. The 1DMMEC--2DFE model is derived to consider better the cross-section geometry of tape wound cores. The model couples the 1DMMEC model to a 2D FEM formulation. The resulting model allows expanding the micromagnetic description of the tape material over the cross-section of tape wound cores.
The 3D micromagnetic simulations with MuMax3 cannot accurately model the iron losses. Direct simulation of the tape is not possible due to the computational burden, and small-scale simulations do not give satisfactory results. However, some magnetization processes in the tape can be examined through 3D micromagnetic simulations. The iron losses predicted with the 1DMMEC model are in good agreement with similar models from the literature. This motivates to attempt to couple the model with the 2D FEM to obtain a more general description of tape wound cores. The iron losses predicted with the 1DMMEC--2DFE model achieve good agreement with measured losses. In some situations, the predicted losses describe the measurements more accurately than the 1DMMEC model. The accuracy of the prediction seems to decrease slightly with thinner tape thicknesses. On the other hand, the simulation parameters were not varied to achieve the best fit to the measured losses in every situation. The computational burden of the 1DMMEC--2DFE model is significant with small excitation frequencies.