The accurate and reliable SOC (state of charge) estimation is difficult, although it is a core factor especially for battery energy storage system. Current studies of SOC estimation theories and models are mainly focused on voltage model, current model, resistance model, intelligent algorithm model, and hybrid model. Specific attentions were paid to estimate the model and their impact factors on SOC. Then, a critical review of available literature on major SOC issues was presented. Influencing factors on SOC were studied and analyzed, such as dynamic hysteresis characteristics, temperature, aging, self-discharge, and rate of charge/discharge. The economy and practicability of the SOC estimation are analyzed and compared objectively.
Received 14 September 2012Accepted 01 February 2013Published online 27 March 2013
This work was financially supported by National Natural Science Foundation of China (No. 51206175).
Article outline: I. INTRODUCTION II. INFLUENCING FACTOR ANALYSIS A. The dynamic hysteresis characteristics B. Temperature C. Aging D. Self-discharge E. Rate of charge and discharge III. SOC ESTIMATION MODELS A. Voltage models 1. Discharge model 2. Open-circuit voltage model 3. Load voltage model B. Current models 1. Ampere hours model 2. Peukert model C. Resistance model D. Intelligent algorithm model 1. Kalman filter model 2. Artificial neural network model 3. Fuzzy logic model E. Hybrid algorithm IV. SOC ESTIMATION MODEL OF BATTERY PACK V. CONCLUSIONS