Voltage relaxation curve‐based state of charge estimation method with reduced measurement time

Abstract

Abstract This paper proposes a method for estimating a battery's State of Charge using voltage relaxation curves. This method offers advantages over the conventional State of Charge estimation methods by reducing the measurement time of the Open Circuit Voltage method and eliminating the need for specialized equipment required in Electrochemical Impedance Spectroscopy. The influence of battery parameters on voltage relaxation curve was analyzed through simulations, and based on this relationship, battery parameters were obtained by fitting the voltage relaxation curve. The State of Charge was estimated using the battery parameter look‐up table for each State of Charge prepared in advance, and the measurement time could be shortened through graph fitting for the initial section of the voltage relaxation curve. The proposed method allows for a reduction in measurement time compared to the traditional Open Circuit Voltage method, while achieving State of Charge estimation with an error rate of less than 5.00 percentage.

Keywords

• battery management systems
• charge measurement
• curve fitting
• state estimation