Battery module performance improvement using active cell balancing system based on Switched-Capacitor Boost Converter (S-CBC)

In this research, we developed an active cell balancing system to improve battery module performance. The active cell balancing system is based on Switched-Capacitor Boost Converter (S-CBC) method which consists of capacitors and DC-DC boost converters. The developed active cell balancing system will select the highest battery cell energy then transferred it to the lowest cell energy. From the analytical result, the optimum energy transferred in the active cell balancing system was using 1.1 F capacitor capacity, 5 Ohm resistance, and 5 Volt of the capacitor upper-lower voltage difference which shows the 0.5 Hz frequency and 50% duty cycle. The active cell balancing system experiment was conducted in two stages using valve regulated lead acid (VLRA) batteries with the nominal voltage 12 Volt and the nominal capacity 7 Ah. The first experiment was conducted by comparing the performance of the active cell balancing system with a conventional switched capacitor circuit in 2 battery series connection which shows that the developed system was 4.6 times faster than the conventional circuit at 0.5 Hz frequency with 81% efficiency. The second experiment was conducted to investigate the battery module performance when discharging process occurred with 1 A applied to 4 battery series connection. The result shows that the voltage differences between battery voltage differences without using cell balancing shows above 0.2 V and continues to expand to 0.8 V and by using the developed system the voltage difference were able to achieved below 0.1 Volt. It also shows 7.5 % performance improvement of the average battery system capacity and energy.