A nonlinear adaptive observer approach for state of charge estimation of lithium-ion batteries

A state of charge estimation method for lithium ion batteries is presented. First, the problem is formulated, and existing literature is reviewed. Then an equivalent circuit is used to model the battery, and an indirect nonlinear adaptive observer approach is developed to estimate the state of charge. Parameter identification and state estimation scheme are discussed. Simulation result based on real-world battery test data is shown to support the validity of the proposed method. Issues related to production code implementation are also addressed.