Battery State Estimation using AC analysis

Batteries are becoming an integral part of daily life because of increased portable appliances, DC UPS systems and green power generation. Importance of on-line battery monitoring of available energy, state of charge (SOC) and state of health (SOH) is becoming essential for efficient use of the battery systems and energy management. All known off and on-line battery monitoring methods use load tests for determining battery condition and/or battery model parameters which indicate SOC and SOH. This paper discusses the on-line impedance based method to determine the SOC and SOH. The sine, square and pulse waveforms are analyzed to determine the deterioration of battery model elements. It is concluded that pulse waveform effectively determines variation of battery model elements and also charges the battery rather than using the energy of the battery to determine the state.