Concept of a novel intelligent battery management system for electric vehicles

Proyect description

Transportation is the major contributor to emissions of greenhouse gases like CO2 and the depletion of fossil fuels. Therefore, a technological transition to an environmentally compliant and sustainable energy supply in transportation is required. While in part synthetic fuels are recommended to quickly achieve this goal, currently electrification of the drivetrain is still considered as the most promising path. This concerns both fuel cell (FCEVs) and especially battery electric vehicles (BEVs). The rapid deployment of BEVs depends on a larger customer acceptance. This requires that the battery is recharged ultra-fast with high reliability and lower cost. Fast charging is mandatory considering the limited energy density storable in Li ion batteries (which represents the best technology available at the time being). Fast charging can be detrimental to the lifetime of the batteries due to irreversible changes in the battery electrodes and electrolytes. This is the bottleneck of the fast charging development. The starting point for the NOVBATCON project is exploring a novel concept for the battery management in collaboration with renowned Chinese scientists. In general, the battery packs of the BEVs consist of hundreds or thousands of cells grouped into several battery modules to ensure the power capability. The safe and reliable operation of the battery pack is vital, thus the battery operation is monitored and controlled by a battery management system (BMS). A typical BMS measures only the total current and voltage of the battery as well as the voltages and temperatures of the individual cells in order to estimate important state parameters like the state of charge (SOC) and state of health (SOH) of the battery, to determine the available power, to control the charging process, to balance the SOC between the cells and in general to guarantee safe and reliable operation of the BEVs. A detailed and rapid information about pending changes in the individual cells and an early diagnosis of degradation onset is not reliably possible with current BMS systems.

The concept explored in NOVBATCON shall survey the internal state of each single battery cell using a special alternating current based method that permits to draw conclusions on changes in the internal state of the battery early on. The data analysis is based on a physical battery model, which will be validated by electrochemical impedance measurements on half-cells. Then, the measurements will be applied to commercial full cells with different SOH to build up the corresponding database. Modern IT methods will be integrated as well to establish efficient control strategies. This shall extend the fast charging capability and prolong the lifespan of the battery significantly. A combination with the concept of reconfigurable battery packs will also be considered. The new techniques shall be realized with low cost circuitry to prevent excessive cost for the BMS. The achievements of the project will be exploited in publications and patents and implemented in follow-up demonstration projects with the associated partners. The project shall also contribute to standardization activities in the area of electromobility.

Comtact Person

Dr. Oliver Schneide
Tel: +49 89 289 18105

Dr. Cuili Chen
Tel: +49 89 289 18073

M. Sc. Göktug Yesilbas
Tel: +49 89 289 18063