Automated Measuring Station for Accumulator Testing
¹Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamycka 129, CZ 165 21, Prague 6 ˗ Suchdol, Czech Republic
2Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Electrotechnology, Technicka 2, CZ 166 27 Pague 6, Czech Republic
*Correspondence: papezovas@tf.czu.cz
Abstract:
The paper describes the design and implementation of the system allowing the testing of the lithium-iron-phosphate (LiFePO4) cell parameters during long-term loading. Manufacturers and retailers, in particular, accentuate their beneficial properties – the possibility of charging and discharging by high currents, minimum influence of the discharge time on capacity, long durability. At the same time, their operational conditions are a lot more strictly defined than those for other types of accumulators. The proposed testing system enables loading the accumulators, consisting of several cells, by periodic discharging and charging processes with various operating currents and various levels of cell discharging. The charging and discharging process control is fully automated; the measuring of the cell operational state is performed automatically during charging and discharging. The data is recorded, and continuously evaluated for the purposes of process management. The measurements enable the comparison of the catalogue data with the parameters of the real products. The testing system design is based on the application of a digital control block, which is completed with an analog control block. The core of the digital control unit is a control computer equipped with a multifunctional input-output card and an array of logically controlled circuit breakers. An accumulator management algorithm, implemented as a control program of the computer, ensures the operation of the accumulator in subsequent charging and discharging periods. The actual accumulator control is based on the evaluations of voltage levels at the cell terminals.
Key words:
Ah capacity, LiFePO4 accumulator, limit parameters, testing