Optimal thermal management for electrified vehicles in cold weather: an investigation of battery pre-conditioning strategies before fast charging using V2X connectivity information

The e-mobility paradigm comes with new possibilities and difficulties to overcome. The vehicle is now an entity that actively interacts with other vehicles, with the cloud and with the environment and a lot of information can be gathered for electronic horizon reconstruction so that the thermal management system uses the least electrical energy as possible while keeping all the systems in an optimal temperature range. This study investigates the possibility and the effectiveness of developing predictive control strategies for the thermal management of electrified vehicles in cold weather, exploiting V2X connectivity information in order to minimize fast-charging duration. The starting point was the existing CRF virtual test rig of the Fiat 500e, and this work tries to address some areas of improvements of the thermal management model and strategies. In particular, the full potential of fast charge is not exploited at all temperatures and the implemented thermal management strategies are not predictive. The work is therefore articulated in three branches: ??The development of a standalone and integrated GT-Suite model starting from the initial coupled GT-Suite/ Simulink virtual test rig. ??Battery preconditioning is performed to keep the battery temperature in an optimal window prior to fast charging in order to minimize the charge duration by allowing higher C-rates, decrease the risk of lithium plating, and slow the battery aging process. ??In order to exploit the information made available by V2X and to improve thermal efficiency a predictive controller is designed to minimize the required heating/cooling power. The analysis showed a significant reduction in charging time when performing battery preconditioning: heating the battery allows to exploit the full potential of fast charging, but it comes at the cost of the energy spent by the heater. Performing battery warm-up enhances the performance of regenerative braking and reduces the battery internal resistance and, consequently, resistive losses. These benefits are especially noticeable when employing a heat pump system instead of the conventional resistive PTC heater. A predictive controller was developed in order to get the battery ready for fast charging at the expected time (e.g., the predicted time of arrival at the fast-charging station). It might also be used to preheat the cabin or the battery when the car is still connected to the electric grid, prior to departure, in order to increase the range and improve passengers’ comfort.