Article

# A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer

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Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637141, Singapore
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Vestas Wind System A/S, Hedeager 42, 8200 Aarhus N, Denmark
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Department of Energy Technology, The Faculty of Engineering and Science, Aalborg University, 9220 Aalborg, Denmark
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Author to whom correspondence should be addressed.
Energies 2019, 12(2), 328; https://doi.org/10.3390/en12020328
Received: 14 December 2018 / Revised: 14 January 2019 / Accepted: 18 January 2019 / Published: 21 January 2019
Medium-frequency (MF) transformer has gained much popularity in power conversion systems. Temperature control is a paramount concern, as the unexpected high temperature declines the safety and life expectancy of transformer. The scrutiny of losses and thermal-fluid behavior are thereby critical for the design of MF transformers. This paper proposes a coupled, semi-numerical model for electromagnetic and thermal-fluid analysis of MF oil natural air natural (ONAN) transformer. An analytical model that is based on spatial distribution of flux density and AC factor is exploited to calculate the system losses, while the thermal-hydraulic behavior is modelled numerically leveraging the computational fluid dynamics (CFD) method. A close-loop iterative framework is formulated by coupling the analytical model-based electromagnetic analysis and CFD-based thermal-fluid analysis to address the temperature dependence. Experiments are performed on two transformer prototypes with different conductor types and physical geometries for validation purpose. Results suggest that the proposed model can accurately model the AC effects, losses, and the temperature rises at different system components. The proposed model is computationally more efficient than the full numerical method but it reserves accurate thermal-hydraulic characterization, thus it is promising for engineering utilization. View Full-Text
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MDPI and ACS Style

Tian, H.; Wei, Z.; Vaisambhayana, S.; Thevar, M.; Tripathi, A.; Kjær, P. A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer. Energies 2019, 12, 328. https://doi.org/10.3390/en12020328

AMA Style

Tian H, Wei Z, Vaisambhayana S, Thevar M, Tripathi A, Kjær P. A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer. Energies. 2019; 12(2):328. https://doi.org/10.3390/en12020328

Chicago/Turabian Style

Tian, Haonan, Zhongbao Wei, Sriram Vaisambhayana, Madasamy Thevar, Anshuman Tripathi, and Philip Kjær. 2019. "A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer" Energies 12, no. 2: 328. https://doi.org/10.3390/en12020328

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