RBF Neural Network and Modified PID Controller Based State-of-Charge Determination for Lead-Acid Batteries

State of Charge (SOC) determination is an increasingly important issue in battery energy storage system. Precise knowledge of SOC allows the controller to confidently use the battery pack's full operating range without fear of over- or under-charging cells. Taking into account of some transformed parameters like voltage and current, this paper describes a novel adaptive online approach to determinate SOC for lead-acid batteries by combining modified PID controller with RBFNN based terminal voltage evaluation model, which is used to simulate battery's behavior while it is under load. Results of lab tests on physical cells, compared with model prediction, are presented. Results show that the ANN based terminal voltage evaluation model simulates battery system with great accuracy, and the prediction value of SOC simultaneously converges to the real value quickly within the error of +/- 1% as time goes on.