Intelligent and Modular Battery Management System (IMBMS)

Batteries are the popular devices known to store energy for later use (in the true meaning of the word). They are an indispensable part of almost all portable gadgets we routinely use at home or in work place. As the storage capacity of batteries grew, it gave rise to the intention of using them for much greater loads such as electric cars. With the increasing awareness within the society for environmental causes the pressure has piled up on car manufactures to produce cars which are powered by batteries other than fossil fuel. The- se batteries are actually a cluster of connected battery cells. They contain many modules which in turn contain a number of cells connected in series. For optimal usage of a Bat- tery the energy stored in each cells need to be balanced. The need of balancing is more pronounced in serially connected battery cells, since the maximum out put a module can give is limited to the output of the weakest cell in it. There are two common ways of ba- lancing energy among cells: passive balancing and active balancing. The former balances a module by dissipating energy from the most charged cell, while the latter transfer it to the lowest charged cell. By so doing not only will it be ensured that the battery is at its optimum but also it will have a longer life. But a Battery Management System is not only about mere balancing of cells. It is a much wider context in which a batte- ry system is continually monitored, monitoring results are communicated and decisions are automatically taken based on the interpretations of monitoring data. In this project such an intelligent battery management system has been developed which addresses the points enumerated above. To this end both the hardware and software components of the system were developed tailored to the requirements encompassed within the scope of this thesis work. The designed hardware passed through rigorous checks which in some cases necessitated modification to the hardware logic. The communication between the software and hardware is ensured through repeated testing while charging and dischar- ging battery cells in a module. Apart from the continuous control of the health of the battery using a number of parameters, evaluation of the BMS Tests showed that the efficiency in the capacity can be increased by 10% in active balancing compared to a similar test without active balancing. This constitutes a significant improvement to the battery life. Although effort has been made to exhaustively compare the improvements due to the implemented BMS, it was not possible to run a large number of tests due to the time consuming nature of the tests. The conducted four tests, however, show a substantial improvement with respect to efficiency, storage capacity, battery life etc.