A Congolese young woman, Ngalula Mubenga, an electrical engineer at the University of Toledo, has developed a new alternative technology designed to equalise battery power referred to as a “bilevel equalizer.”
The innovation could lead to longer-life batteries for EVs and is also relevant to grid stations, satellites and other energy storage systems. The device combines the high performance of an active equalizer with the low cost of the passive variety.
The technology arranges cells into sections where each is balanced by a passive equalizer as the entire section is balanced by an active equalizer. Mubenga said the solution could help electric vehicle batteries hold their charge longer.
Lithium-ionBatteries are constructed in a series of cells but one bad cell can disable an entire energy storage system. Balancing the battery load often requires an equalizer consisting of either a passive circuit, which can be inefficient or an active circuit, which is far more expensive.
“If there are 120 cells in a battery, divide the cells into 10 groups of 12. Then you only need nine active equalizer units and 120 passive equalizer units using the bilevel equalizer,” Mubenga says.
With current active equalizers, manufacturers would have to use 120 active equalizers. For manufacturers that can’t afford to use only active equalizers, the bilevel equalizer is the solution to the problem, she says.
Mubenga who is originally from Democratic Republic of Congo had a serious problem and promised herself that if she made it out alive, she would work to find a solution so people wouldn’t die because of lack of electricity.
Mubenga, an assistant professor, collaborated on the project with Tom Stuart, professor emeritus in the UT Department of Electrical Engineering and Computer Science, who had the idea for the bilevel equalizer. The UT researchers say they are licensing the hybrid equalizer and retrofit kit to manufacturers.