MPC-based Constant Temperature charging for Lithium-ion batteries

During fast charging of Lithium-ion (Li-ion) batteries, the high currents may lead to overheating, decreasing the battery lifespan and safety. Conventional approaches limit the charging current to avoid severe cell overheating. However, increasing the charging current is possible when the thermal behavior is controlled. Hence, we propose Model Predictive Control (MPC) to generate fast charging current maintaining the cell's core temperature constant. For this, the cell's electro-thermal limitations and the thermal dependencies should be included in both the charging strategy generation and the internal states estimator. A battery (Samsung INR18650-20R) electro-thermal model is generated and corroborated through several laboratory experiments. Then, a BMS is built and programmed to provide the internal states of the cell via the Unscented Kalman Filter (UKF). Finally, the closed-loop operation and electro-thermal regulation is achieved with MPC.