Hybrid-Type Intelligent State of Charge Observer of Li-Ion Batteries

This paper proposes a new approach to estimate the state of charge of Li-ion batteries, the hybrid-type intelligent state of charge observer. The proposed observer has the combination structure of a sliding mode observer and a fuzzy PI observer and adopts the expert system based on Takagi–Sugeno fuzzy reasoning to switch those two nonlinear observers. This scheme embodies the advantages; the fast dynamic response by the sliding-mode observer and the chattering attenuation in steady state by the fuzzy PI observer. Some comparative simulation verifies and demonstrates the performance and the superiority of the proposed observer.