Reliability assessment of EV fast chargers

Project description

Urgent efforts towards global decarbonization are leading to the massive increase in the number, variety, and complexity of power electronic components and systems. Nevertheless, the transition from fossil fuel to electric vehicles (EV) is held back by concerns about their long charging times and limited durability. The development of fast-charging EVs is putting significant pressure on the power converters since the converter and its components need to conduct more power, which leads to increased thermos-mechanical stresses and failures. The semiconductor devices are fragile components of the power electronic systems because they undergo large thermal cycles and are build from stacked layers with different coefficient of thermal expansion (CTE).

Silicon-carbide MOSFETs have in general a better efficiency, smaller size, higher allowable voltage rating and temperature operations. However the failure mechanisms and reliability will be different and must be investigated more. Furthermore, the integration of smart sensors are helping to increase system sustainability by monitoring the conditions and degradation of the power electronic components. A part of this project is to assess the end-of-life of the MOSFETs and predict the remaining useful lifetime of the components and systems. The power cycling test is available to accelerate the thermos-mechanical degradation and obtain practical information.

The research questions associated with this PhD project are as follows:

• What are the failure mechanisms and reliability differences between silicon and silicon-carbide MOSFETs?
• Which electric and thermal parameter of the MOSFET is best suited for tracking the degradation process?
• How do AC/DC converter topologies for large power EV charging station compare in terms of reliability?
• Which strategies can be applied to prolong the remaining useful lifetime of the converter?

PhD Candidate
Ir. Margo Molenaar – M.Molenaar-1@tudelft.nl

Supervisor
Dr. ir. Aditya Shekhar - A.Shekhar@tudelft.nl

Promotor
Prof. dr. ir. Pavol Bauer - P.Bauer@tudelft.nl