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

Haonan Tian, Zhongbao Wei, Sriram Vaisambhayana, Madasamy Thevar, Anshuman Tripathi and Philip Kjær
Additional contact information
Haonan Tian: Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637141, Singapore
Zhongbao Wei: Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637141, Singapore
Sriram Vaisambhayana: Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637141, Singapore
Madasamy Thevar: Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637141, Singapore
Anshuman Tripathi: Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637141, Singapore
Philip Kjær: Vestas Wind System A/S, Hedeager 42, 8200 Aarhus N, Denmark

Energies, 2019, vol. 12, issue 2, 1-16

Abstract: 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.

Keywords: electromagnetic analysis; thermal-hydraulic analysis; oil natural air natural; medium frequency transformer (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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