Wang, Zhaoxin

PhD student Zhaoxin Wang

PROJECT TITLE: : Study of Insulation of High-voltage High-frequency Transformers in Modern Power Electronics Based on Electro-thermal Analysis

PhD period: 2020.11.01 – 2023.10.31.
Section: Electric Power Systems
Research Programme: Modern Power Transmission Systems
Supervisor: Claus Leth Bak
Co-Supervisor: Qian Wang, Henrik Sørensen
Contact Information

Funding: China Scholarship Council (CSC)


As the key component of power electronic transformer (PET), the high-frequency high-voltage (HVHF) transformer plays an important role in electrical isolation and power transmission. In contrast to traditional line frequency transformers, HVHF transformers operate on higher switching frequencies with square voltage and in general non-sinusoidal current waveforms, depending on the characteristic of the power electronic converter topology. The effect of high-voltage, high-frequency and high-temperature will result in local temperature rise, insulation failure and accelerating insulation aging of HVHF transformer. Unlike the traditional line frequency transformers, HVHF transformers have not yet reached the technological maturity, leaving many areas open for research.

To that end, the present PhD project focuses on the technical challenges tied to multi-physics modelling and insulation electro-thermal characteristics of HVHF transformers. Firstly, a detailed multi-physics analysis model will be built to obtain electromagnetic field, temperature field and fluid field accurately of the HVHF transformer, and the results of temperature distribution will be verified by thermal test of the HVHF transformer. Secondly, partial discharge·(PD) test and breakdown test will be conducted to evaluate the electro-thermal characteristics of insulation under multi-stress of high-voltage high-frequency and high-temperature. Third, electro-thermal aging test will be conducted, and the lifetime prediction model of HVHF transformer insulation will be built based on the multi-physics simulation and electro-thermal characteristics of insulation.

The researches mentioned above would have the significances to have a deep look in the nonlinear coupled multi-physics of electro-magnetic, fluid and temperature, as well as identify the weakness of the insulation in HVHF transformers, evaluate the electro-thermal characteristics of insulation under the actual working conditions of HVHF transformer, have a better lifetime prediction of HVHF transformers insulation and provide theoretical and experimental reference for optimal design, insulation cooperation and actual operation of HVHF transformers in modern power electronics.


Publications in journals and conference papers may be found at VBN.