A generic in-circuit modeling approach for electrochemical batteries

A modeling approach for the electrochemical batteries, which is suitable for in-circuit parameter extraction is presented. The charge flow in an electrode reaction is governed by the mass transport regime within the cells. For sufficiently higher charge flow rates, the mass transport rate decides the limit. Hence modeling the battery, centered around the mass transport mechanism can have the benefits of dynamic and run-time behavior modeling, using the model parameters extracted from the dynamic in-circuit behavior of the battery. The electrical equivalent circuit model presented, captures the diffusion characteristics and the resulting over potential by way of segment wise diffusion modeling. The number of segments for diffusion modeling is restricted to three, for ease of in-circuit computation. The model provides scope for enhancement by addition of coupled behavior with the thermal domain. This modeling method is suitable for a real time model based Battery Management System (BMS). Practical experiments for extracting the model parameters for a lithium-ion LG1850 cell are carried out and the result is analyzed indicating the feasibility of the proposed modeling approach.