Fig 1:Driving profile executed on CEA’s test bench
Electric vehicule are bring into focus to be a green and clean car. New concept of car with more safety, comfort and reliability. The mains challenges on the subject are the price and autonomous. Ihecobatt project keeps focus on these two aspects. These can be upgrade by eco-conception and energy management. The battery pack needs to have a thermal management. The goal of a thermal management system is to deliver a battery pack at an optimum average temperature. CEA works consist in characterizing, understanding and optimizing the new heat exchanger management with CIDETEC. The efficient and eco conception of the hardware part are realized by MIBA with AUDI and CEA support.
To better understand this optimisation aspect, we need to know what is the power consumption of the thermal management with the actual commercial heat exchanger. The first part of the work was to make an evaluation of the current one to be able to evaluate the improvements. During the tests campaign the BP was tested in several conditions. To illustrate the thermal management requirement we will use one of this test. The first graph below showed the cooling power applied during the test. The second show the evolution of the temperature inside the battery pack, on the cells.
Fig 2: Temperature evolution during drive cycling profile
The instant demand of cooling grown until 4kW of cooling power. The maximum temperature of the cells rises to more than 50 ° C. The cooling power consumption are approximately 6.4 kWh, that represent 10% of the Battery pack capacity. This represents several tens kilometres of autonomy. One goal of the project is to improve overall powertrain energy efficiency up to 5% and reduce this part of cooling power needed. This will increase the efficiency and autonomy of the vehicle.
