LAUSR

Abstract In electric vehicles, Battery Management System (BMS) plays a significant role in cell voltage equalization. In the passive cell voltage balancing method, strong cells dissipate excess energy through resistors in the form of heat. So, this will increase the overall battery pack temperature, which may damage the battery pack when it exceeds its permissible temperature limit. Whereas in the active cell balancing method, the extra energy will be stored in energy storage elements and that stored energy will be transferred to the lowest voltage cells to equalize the cells voltages among all the cells in the battery pack. The existing active cell voltage balancing methods have some disadvantages like low efficiency, bulk in volume, less reliable and more time taking for cell voltage equalization. To overcome these disadvantages in the active cell voltage balancing, in this paper, a new optimized active cell voltage balancing method based on a closed-Loop Switched-Capacitor Structure (CLSCS) has been proposed. The proposed method attains the shortest path from one cell to another cell in the battery pack. Consequently, it will improve the voltage equalization, speed and overall efficiency of the battery pack, as well as it will reduce the cost of the battery pack. This method is robust and adaptive for the imbalance of the cell voltages. Both simulation and experimental results are presented to validate the proposed work. The simulation work is carried out on a MATLAB environment. The overall cell voltage balancing speed is improved with the proposed method and the efficiency of the proposed converter structure is up to 95%.