Modeling of Lithium-Ion Battery Management System and Regeneration Control Strategy for Hybrid Electric Vehicles

Battery management system (BMS) plays a key role in the power management of hybrid electric vehicles (HEV). It measures the state of charge (SOC), state of health (SOH) of the battery, protects the battery package and extends cells' life cycles. For HEV applications, lithium-ion battery is usually selected as electric power source due to its high specific energy, high energy density, and long life cycle. However, the non-linear characteristic of a Li-ion battery, complicated electro-chemical model, and environmental factors, raises the difficulties in the real-time estimation of the SOC for a Li-ion battery. To address this challenge, a BMS for HEVs is modeled with MATLAB/Simulink. In addition, a regenerative braking control strategy is proposed to determine the magnitude of the regenerative torque based on the battery SOC. The motor-generator system is optimized and modeled with regard to the operating time and power contribution of the e-motor during acceleration and the regeneration behavior of the generator during braking for maintaining the battery SOC within a proper range to achieve the longest battery life cycle and stable performance.