Data processing, state functions and advanced BMS

In the Sensibat project, work package 4 dealt with incorporating novel technology and insights gained from the other work packages. It can be considered the culmination of all research and development performed in the framework of Sensibat. It touched two aspects of the developed battery technology:

  • Development of the Battery Management System (BMS) and all supporting hardware to read the integrated sensing technology and the construction of a demonstration platform,
  • Development of new, advanced state estimation techniques taking advantage of those novel integrated sensing matrices.

The BMS is the heart of any integrated battery system and controls its operation. To enable this, the BMS needs to be aware of the state of the battery system, which in traditional systems is limited to applied current, voltages of the cells or modules, and some thermal values. However, in Sensibat we have developed smart cells with integrated temperature and pressure sensors. This additional information is read out by the sensor readout circuit, which is the result of Task 4.1. This advanced circuit reads the sensor matrix from all cells sequentially, packages this information on the BMS-slave and transmits this to the BMS-master, both the result of Task 4.2. A demonstration module with supporting hardware for sensor verification was built during Task 4.3 and is the representation of all developed technology during the project. The module contains an advanced cooling system with which the cooling can be focused on measured hotspots on the cells surfaces, enabled by the matrices of thermal sensors inside the cell.

The integrated sensing technology provides a 2D (2 Dimensional) view on the thermal and pressure evolution of the cells over their surface. This information helped understand how the cells behave during operation, what operation conditions cause rapid heating or volume expansion. This understanding of the influence of parameters like current-rate, State of Charge (SOC) and State of Health (SOH) on the thermal and pressure behavior has led to the development of highly advanced new state estimation techniques, developed in the context of Task 4.4. These models have improved the accuracy with which we track the SOC, SOH, SOP (state of Power) and SOE (state of energy), as well as the State of Safety (SoS), which is a novel technique for quantifying the safe usage of the battery system.

Finally, the inclusion of a reference electrode in the Level 2 cells has enabled the development of improved SOC estimation methods, using the individual electrode potential measured against the reference electrode as input. This work was completed in Task 4.5 and has caused improvements in our insight in the way both electrode’s potential behavior changes over time.