Part 1 of this article explains the challenges associated with implementation of large Li-Ion battery packs for automotive applications and highlights the advantages of active balancing vs. passive balancing methods. Passive balancing has dominated Li-ion battery packs in the past. Economic pressures are forcing automotive OEMs to choose more advanced, active balancing systems to squeeze out every drop of energy from the battery pack.
The electrification of automobiles has finally reached the tipping point as indicated by the rapid growth of the number of hybrid-electric (HEV) and electric vehicles (EV) entering or planned to be introduced to the market.
The major hurdle to the success of the EVs is the battery. Recent progress in Li-ion battery technology increased the power and energy density of battery cells and reduced their cost. In order to mitigate the “range anxiety” plaguing early EVs and being the main concern of potential customers, further improvements are needed.
The battery pack is one of the most expensive and potentially least reliable components of the EV. A high performance Battery Management System (BMS) is the answer to the weaknesses of HEV and EV battery packs.
Charging of battery packs consisting of tens and in some cases thousands of cells w/o overcharging a single cell while balancing all cells during charging, idle and discharging states and mitigating the effects of cell charge and capacity mismatch requires state-of-the-art active BMS.
Active BMS lowers the overall cost of battery pack by eliminating the need to oversize the pack to account for the effects of cell-to-cell parameters variation and uneven ageing. The system plays a crucial role when the old cells are replaced with new ones and the pack becomes mismatched—allowing use of cells with larger spread in their parameters which results in increased manufacturing yield. Cost of warranty and maintenance is also reduced. The active BMS enhances performance, reliability, and safety of the battery pack while helping to reduce the cost.
Read the full article here, courtesy of Automotive Designline Europe.
Part 2of this article reviews common active balancing methods and gives details of a unique active cell balancing battery management system.