Real-time optimal fast charging of Li-ion batteries with varying temperature and charging behaviour constraints

To expand the adoption of battery-operated portable consumer products and reduce the fear of running out of charge, the manufacturers and researchers have developed various health-aware fast-charging protocols. However, the different health-conscious fast charging algorithms only generates a pre-defined charging profile based on initial operating boundary conditions without having the option of real-time controls. In this work, a real-time optimal fast charging protocol is implemented by using Pontryagin's Minimum Principle (PMP) to solve the optimal control framework having a trade-off between charging time and ohmic heat generation. Modifying the control concepts of costate jump conditions and from extensive offline optimization results, the real-time optimal fast charging protocol is examined for varying operating constraints. The effect of different boundary conditions, mainly due to charging behaviours, on the charging profile and other sensitive parameters are also investigated and compared with a standard CCCV charging algorithm. Finally, the comparison between a typical optimal fast charging profile and a standard 2C CCCV protocol is experimentally examined.