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

This paper 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 experimental verification using a 3.8V/2600mAh Samsung Li-ion battery cell at temperatures between -20 and +50 deg C are presented.