Multiple Cell AC/DC Smart Battery Design

Traditional multi-cell battery packs use a fixed configuration to connect multiple individual battery cells in fixed configurations to achieve pre-determined voltage and current. Even with modern advances in battery chemistry and greater power density, this fixed configuration results in low reliability, low fault tolerance, and non-optimal energy conversion efficiency. This system of manufacture is hindering advances in battery performance. This paper proposes a novel scheme to manufacture batteries by individualizing cells. By changing the packaging and adding low cost circuitry, a single cell in a battery pack will be able to control its orientation with other cells in a system. The idea has potential to revolutionize the way in which battery systems are developed and controlled. By using Texas Instruments value line MSP430 microcontrollers, the cost of the system can be minimized. The use of these low cost microcontrollers makes it possible to monitor voltage and temperature levels on individual cells. Also, by utilizing the same microcontroller, the individual cell is capable of shifting individual battery cells from off state, to a positive or negative polarity. The ability to switch single cells will make it possible to create a multi-level DC output. This independent switching scheme will also make it possible to create a modified sine wave AC output. The possibilities of switching to negative polarity will double the peak-to-peak voltage of the AC waveform. The battery will also be capable of identifying and implementing only the cells that are in optimal condition. Using cells at optimal temperature and state of charge will prolong the life of each cell. A battery system that individualizes each cell into a replaceable package makes replacement of “dead cells” possible. These are the cells that currently cause traditional battery packs to be replaced. With such systems available, not only will efficiency of large multi-cell battery systems increase, but with replaceable cells the cost of ownership of a complete battery pack will decrease over the lifetime of the system.