An Optimized Dual Active Bridge Converter for EV On-board Charger

Currently, limited full-electric mileage and unsatisfactory charging time are the two main barriers in fast deployment of electric vehicles (EVs). In order to overcome the mileage limits, significant work and development have been devoted on improving the battery performance. Taking the newly released Tesla Semi truck as an example, the capacity of the battery pack is estimated around 1MWh which can be seen as a breakthrough of energy level. However, a larger battery capacity also means a longer charging time. Consequently, high power EV chargers are needed to balance these two parameters to achieve the goals of fast on-board charging and ultra-fast off-board charging.
Usually, the higher power rating of a converter, the larger size it takes for the power components to undertake the voltage or current stress. Increasing the power density is therefore necessary for the power converters, especially for the on-board chargers. Nevertheless, the thermal density is also increased, which may deteriorate the lifecycle of the charger. For this reason, the reliability should also be accounted in the design phase.
The aim of this PhD project is to design a universal and optimized robust charger for EVs, including the following aspects:
1)Develop a compact structure for the on-board charger to boost the charging power density
2)Optimize the control and modulation method to improve the charging efficiency
3)Broaden the operating range of the charger so that it can work universally in varying grid voltages and battery pack voltages.
4)Electro-thermal analysis of the designed charger to cope with the thermal stress issue
Finally, reliability assessment and simultaneous simulation will be performed and a practical on-board charger will be established to validate the theoretical analysis.

Funding: CSC Scholarship