An Adaptive Sensorless Measurement Technique for Internal Temperature of Li-Ion Batteries Using Impedance Phase Spectroscopy

This article proposes an adaptive sensorless measurement technique for internal temperature of lithium-ion (Li-ion) batteries. The proposed technique is based on measuring the impedance phase of the battery in real time by a simple search algorithm. The proposed technique then identifies the zero-crossing frequency at which the phase of the impedance is zero. From the value of the zero-crossing frequency, the cell's internal temperature is estimated. Details on the proposed technique followed by the experimental verification using a 3.8-V/2600-mAh Samsung Li-ion battery cell at temperatures between -20 °C and +50 °C are presented.