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Zheng, Changjiang

PhD student Changjiang Zheng

PROJECT TITLE: Insulation Evaluation and Design in Power Electronic Components and Systems 

PhD period: 2019.09.01 – 2022.08.31.
Section: Power Electronic Systems
Research Programme: Modern Power Transmission Systems
Supervisor: Claus Leth Bak
Co-Supervisors: Qian Wang and Huai Wang
Contact Information

Collaborator: To be announced later.
Funding: Self-financing.

ABSTRACT

Modern power electronics is playing an increasingly important role in energy transmission systems, with the rapid growth of renewable energy. The evolution of modern power electronic components and systems (including power modules, passive components-capacitors and inductors, medium/high frequency transformers, etc.) develops in the direction towards higher voltage, higher frequency, more compact package and more severe operation conditions (high temperature, humidity, etc.), causing problems in the reliability of power electronic components and systems, especially to the reliability of their insulation system.

The reliability of electrical insulation systems under AC electrical stress has been investigated for decades. However, the insulation systems of power electronic components and systems are exposed to high frequency voltages with distortions due to application of high-frequency switch devices (IGBT modules, for instance). The high frequency voltages with fast fronts can cause more severe problem for an insulation system, compared with power frequency AC voltages. Distorted high frequency voltages can accelerate intrinsic aging of insulation through electro-mechanical fatigue. Also, high frequency voltages lead to increase of dielectric and ohmic losses in the insulation which causes localized overheating. What’s more, partial discharge activities in the insulation will be intensified under distorted high frequency voltages with fast fronts. As a consequence, the insulation issue is one of the key factors that limit the evolution of modern power electronic components and systems. Therefore, the insulation evaluation and design in power electronic components and systems is of great importance and significance.

The overall objective of this research program is to develop reliable theories, models and methods to evaluate and design the insulation in power electronic components and systems. The detailed objectives are showing as follows:

  • Simulation of electric field distribution and maximum electric field magnitude in various power electronic components and systems;
  • Development of reliable testing methods to measure and evaluate the partial discharge behavior in power electronic components and systems;
  • Establishment of lifetime model of various power electronic components and systems in terms of insulation failure;
  • Development of design guides and tools (software-based) for insulation in various power electronic components and systems.

PAPERS

Publications in journals and conference papers may be found at VBN