Optimal Charge Equalization Controller

Electric vehicles (EV) contribute in part to solve the global environmental issues as alternative to the conventional internal combustion engine-based transportation. EV demands a compact drive train architecture with elevated energy storage system of high capacity and efficiency such as lithium-ion battery pack. However lithium-ion battery needs protection from being undercharged or overcharged that causes rapid reduction of its life and efficiency. This book presents an optimal charge equalization controller (CEC) for monitoring and balancing the voltage levels of lithium-ion battery cells. The proposed equalization algorithm processes the CEC operation for balancing both the overcharged and undercharged cells via a bidirectional flyback DC-DC converter. The equalization by charging and discharging employs CC-CV charge PI control and DCM discharge control techniques. The particle swarm optimization algorithm is applied to optimize the PI controller parameters for generating regulated PWM signal to the converter so that a high capacity lithium-ion battery charging is maintained.