Electric vehicles and their batteries are complex systems and therefore issues with respect to range anxiety, cost, safety and reliability have to be addressed on system level: materials, cells, system design, battery management system (BMS) and ultimately on the vehicle level...
Electric vehicles and their batteries are complex systems and therefore issues with respect to range anxiety, cost, safety and reliability have to be addressed on system level: materials, cells, system design, battery management system (BMS) and ultimately on the vehicle level and in the interaction with its environment.
Current state-of-the-art battery management systems predominantly react to â€˜symptomsâ€™. They have only a rudimentary knowledge of the battery state and use rules-of-the thumb to manage the battery state. Due to this approximate and reactive way of working, the safe operating range of the battery has to be significantly narrowed down to ensure safe and reliable operation. This leads to inefficient use of the battery and still doesnâ€™t give a 100% guarantee to prevent unsafe situations or circumstances that are damaging to the battery.
The overall objective of EVERLASTING is to develop model-based, flexible, modular, cost-effective battery management technologies based on an in-depth understanding of the internal state of the battery enabling pro-active control at the cell-level. This â€œnext-generationâ€ model-based and pro-active battery management system will help in solving the issues of range anxiety, cost, reliability and safety of EV battery systems. Developing techniques to cost effectively monitor batteries and manage important performance measures while predicting battery aging and failure remains a key technological challenge. No single innovation will completely solve the challenges of battery management. However, comprehensive solutions that combine data from a multitude of novel sensors with advanced models and efficient thermal and load management techniques can drastically enhance the utilization and rate capabilities of battery systems within safe limits while extending their lifetime and reliability. An energy management system that successfully addresses all these needs would be a game changer.
By intelligently combining the more accurate battery information with road, vehicle and driver data, we intend to offer a more accurate higher-level driver feedback. This will give the driver a bigger trust and hence a lower range anxiety.
The second objective of EVERLASTING is to develop a standardized BMS architecture (hardware, software and interfaces) and to develop reliability testing procedures for BMS to further increase reliability. This information will be publically accessible, so that the whole EV community can benefit from this standardization work. This standardized BMS architecture which will be proposed to appropriate standardization working groups outside of EVERLASTING, so that this will be the starting base for further standardization work to the benefit of the whole EV community. Such standardization will lead to a cost reduction due to interchangeable components, specialization, competition and economies of scale.
The project is well on track to achieve its foreseen goals. All research work packages are now going to its validation phase.
Objective 1: develop model-based, flexible, modular, cost-effective battery management technologies based on an in-depth understanding of the internal state of the battery enabling pro-active control at the cell-level.
The EVERLASTING partners have selected a Li-ion battery cell (NMC chemistry) which has been characterized in detail and on which ageing and safety tests are being executed. This data is needed for the development of all different battery models and algorithms for the BMS.
A complete safety testing tool-set has been defined and many safety tests have been conducted. Some test methods have been improved like e.g. the abuse method to create a soft internal short circuit within a tested cell. The capacity to detect a thermal runaway precursor is a key point to improve safety. The capacity to detect those precursors has been evaluated and demonstrated at early stage (early warning diagnostic algorithm using efficient parameters generated from the battery voltage and current measurements) and at middle and late stage (using acoustic and strain sensors). The ageing tests (life & drive cycling and calendar ageing) are performed using representative charge and discharge profiles. Based on the results of these aging tests, the developed algorithms, models and tools are now being validated.
To improve the lifetime of batteries, EVERLASTING is studying thermal management designs and is investigating load management strategies for balancing circuits and battery reconfiguration topologies. For the thermal management a combined active/passive cooling solution (air + PCM) is being evaluated on a dedicated lab test setup. For the load management strategies, the evaluation focused more on the dissipative balancing which showed more promising results.
EVERLASTING aims to extend the driving range without changing the battery size. This can be done by expanding the operational limits of the battery itself, of course always staying within the safety limits. Also the energy management system of the whole driveline of an electric vehicle has an important impact. EVERLASTING developed and validated simulation models of all main components and ran several vehicle tests. First simulation results look promising and the range predictor and optimizer will now be validated on the electric bus demonstrator.
Significant progress has been made on virtual test benches within Simcenter Amesim supporting advanced BMS research (from MiL, SiL to HiL). This will allow a fast and efficient way to consider battery ageing when developing BMS strategies, as well as ways to protect the battery or deal with subsystems faults.
Objective 2: develop a standardized BMS architecture and develop reliability testing procedures for BMS.
For the latter, a public deliverable D2.5 has been finished which will be updated at the end of the project. For the first, a very detailed analysis of the state of the art on BMS systems on the market (D6.1) and on the requirements for research and prototyping (D6.2) has been finished. A dedicated workshop on BMS Standardization has been organized to disseminate first results and to collect input from key industrial players and standardization bodies. All information has been summarized and made public via D6.7 â€œBattery Management System standardâ€.
EVERLASTING has been very active in disseminating the research results in scientific journal/conference publications and on the project website: 10 journal papers, 11 refereed conference papers, 34 non-refereed conference/workshop publications, 9 white papers and 19 public deliverables.
Objective 1: Going into validation phase in different lab test setups, in the VDL electric bus demonstrator and in the EVERLASTING battery pack demonstrator in the VOLTIA eVan. First preliminary research results look promising. Final results will be described at end of the project.
Objective 2: Continue contacts with relevant stakeholders to further support standardization activities outside of EVERLASTING project. Update of deliverable for reliability testing procedures for BMS at end of project.
Impact: Raising awareness of vital and positive role of battery management systems. EVERLASTING consortium is well-balanced which leads to impacts on different levels from commercial exploitation, high-quality scientific research and updated student courses.
More info: http://everlasting-project.eu/.