The thermal management of electrified vehicles

CESA abstract

When running on pure electric mode, electrified vehicles offer a very efficient energy conversion. Less than 3 kW in average is needed to drive an EV over an urban cruise. Consequently, the management of additional power demands of thermal functions, e.g. the cooling or the heating of the vehicle passenger cabin, or that of battery and power electronics, has a major impact on the overall vehicle power balance. A new system approach for thermal management, combining an innovative architecture, dedicated technologies and relevant control strategy, becomes decisive to offer a significant cruising range, secure the battery life time and also ensure quick engine response.
Within the scope of Vega/Thop, a cooperative project including six partners (Valeo, Renault, Saint Gobain Sekurit, Hutchinson, INSA/Cethil, LINC) funded by Ademe, a new thermal architecture was designed, prototyped and tested on benches and lab cars in order to assess the potential of such innovative thermal concept.

This paper outlines the main challenges and the outputs of this project:
- the review of thermal needs, with a focus on the passenger cabin requirements for comfort, and their associated impact on vehicle performances at system level;
- the way to drastically reduce the cabin thermal needs with same perceived comfort, combining cabin treatment, advanced air management and alternative comfort strategy;
- the setting up of a new thermal architecture that combines heat networking, recovery and storage capabilities, looking for synergies between thermal needs and heat losses so as to minimize consumption.
- the implementation of a heat pump to leverage “free” low temperature heat sources, such as ambient air or internal heat inertia and losses
- the benefit of a transient control strategy, in order to manage different operating modes and related “ramp up” or cycling phases, according to the vehicle usage profile.
As a conclusion, typical power savings compared to current serial EV will be presented on different scenarii, based on the results from tests campaigns and simulations analyses.

By Daniel Neveu (R&D program manager, Valeo Thermal Systems) and Osoko Shonda (Innovation Project Leader, Renault).