Online battery monitoring using model based approach – impedance

Batteries are becoming integral part of day to day life with increase in local generation. A more effective battery monitoring and Management techniques are required to maintain the batteries. Impedance based monitoring is becoming a very effective procedure to do the same. Various techniques have been proposed. The Randels model is the most appropriate circuit to explain the phenomenon of the battery. Determining the elements or their change can help us determine the SOC and SOH of the battery.

The proposed method determines the change of Rs (electrolyte resistance) and Cd (capacity representation) to understand the variation of State-of-charge (SOC) and State-of-health (SOH). The varying resistance approach implemented through a boost chopper is implemented to determine the change in Rs. The FFT analysis data is extracted from the voltage and current waveforms of the battery to implement the Electrochemical Impedance Spectroscopy (EIS) in the modified form. This is a good experimental technique for online determination of battery SOC and SOH. The implementation is done using MATLAB Simulink.