Online Battery Electrochemical Impedance Spectroscopy Measuring and Applying Method

To enhance the absorption capacity of renewable energy, energy storage systems are needed to stabilize the fluctuation power of renewable energy. Among existing energy storage systems, battery energy storage systems have significant advantages and have therefore developed rapidly. However, a major problem faced by battery energy storage systems lies in the large number of batteries and differences in battery parameters, which can lead to state deviations during system operation, further leading to short board effects, circulating currents, and even battery failures. Accurate estimation of battery status is crucial for improving the economic and safety performance of energy storage systems. Among them, as the electrochemical impedance of the battery itself is an internal parameter of the battery, it can directly map the battery state, and its characteristics are manifested externally as electrical characteristics, so it can be used to achieve accurate state estimation. This article proposes an accurate measurement method for battery impedance and a state estimation method based on battery electrochemical impedance spectroscopy, and verifies the state identification accuracy of the two methods. It can be obtained that the deviation of state of charge (SOC) < 4%, and the deviation of state of health (SOH) < 5%.