Tag Archives: isolated solar power system

1141–1151 V. Papez and S. Papezova,
Optimization of the balancer for LiFePO4 battery charging
Abstract |
Full text PDF (415 KB)

Optimization of the balancer for LiFePO4 battery charging

V. Papez¹ and S. Papezova²,*

¹ Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Electrotechnology, Technicka 2, CZ166 27 Pague 6, Czech Republic
² Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamycka 129, CZ165 21 Prague 6 ˗ Suchdol, Czech Republic
*Correspondence: papezovas@etf.czu.cz

Abstract:

Balancers of various constructions are currently used for the operation control of the batteries connected in series. Unidirectional balancers ensure proper charging of all battery cells in a way that the first loaded cells should not be overcharged. Active balancers distribute the power, supplied to already-charged cells, to other cells; the power is further consumed by the passive balancers. Bidirectional balancers enable distributing the power between the cells during the discharge process, as well. This process thus protects the fastest discharging cells against the deep discharge. Passive balancers are most often used in batteries charged by the currents up to 20 A. If there are not big differences between individual cells in the battery, passive balancers reduce the efficiency of the charging process by only a few percent. They are the cheapest and most reliable. Optimally adjusted balancers with very low internal resistance deteriorate the efficiency only by about 1%. Commercially available balancers, working on the principle of a switch, periodically connecting the load resistor to the cell, deteriorate the efficiency to a greater extent, by about 5%. Optimized balancers, whose construction is described in the paper, work on a principle of a linear feedback controller. They can work with a maximum charging current up to 20 A, they have very low dynamic resistance of about 1 mW, and are absolutely stable. Their properties are further compared both with previously used circuits and commercial circuits.

Key words:

, ,