Thermo-electrical battery test stand

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Research oriented tests of batteries, fuel cells and redox flow batteries and those tests accompanying their development are typically conducted independently on cell level and on system level (serial-parallel connection or stack). Thus, a separation of cell-to-cell variation and effects of inhomogeneities during operation of cells are not possible. Goal of the proposed project is to analyse the electrochemical and electro-thermal behaviour as well as the degradation behaviour of single cells and modules such that both the statistical effects and the amplifying effects due to the inhomogeneous operation are identified and quantified. Necessary prerequisite is a tight coupling of tests on cell level (6 V channels) with tests on module level (60 V channels). The coupling incorporates the applied current profiles, the cut-off limits (voltage limitations), the adaption of load profiles over the life time of the devices under test (changed capacities and power capabilities), time synchronisation (e.g. same rest periods, same test interrupts for reference tests) as well as same temperature profiles in a climate chamber. All of the above are crucial test conditions for the targeted analysis. The necessary coupling will be guaranteed in the proposed test setup by a system-encompassing control software that allows a programming of test cycles across all test channels and voltage levels. The second goal of the batter test stand is the realisation of an aging minimal fast charging control of battery modules based, first, on a coupled usage of pilot cell and, second, on an embedded digital twin. In the first case, the pilot cell undergoes a detail diagnosis. The results gained online are utilized for a derating of the charging current of the battery module. In the second case, model-based information on the electrochemical behaviour of a single cell is incorporated via software-in-the-loop into the feed-back control loop of the charge control in real time.