Sensorless Current Estimation of LiFePO4 Battery using an Unknown Input Observer

This paper presents an unknown input observer (UIO) to estimate the input current and state of charge (SOC) of a LiFePO
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pouch cell. The 1-RC battery model was developed to determine the dynamic behavior of a real battery. Battery characterization was done using the hybrid pulse power characterization (HPPC) test. To evaluate the proposed method, validation of the battery model and UIO with reference to the coulomb counting method is done. Traditional methods estimate SOC by sensing the battery voltage, current, and by using a mathematical model of the battery, where the accuracy of the SOC depends on the accuracy of the current sensor. The suggested strategy estimates SOC by eliminating the current sensor and utilizing UIO. The proposed UIO-based SOC estimation technique has the potential to significantly reduce the cost and complexity of battery management systems while improving the reliability and accuracy of SOC estimation. The technology has broad implications for a wide range of applications, including electric vehicles, renewable energy systems, and portable gadgets, where accurate and consistent battery management is critical for optimum system performance.