Frequency-Variable Resonant Self-Heating Technique for Lithium-Ion Batteries at Low Temperature

This article presents a frequency-variable resonant self-heating technique for improving the heating speed of lithium-ion batteries at very low temperatures. In contrast to the conventional heating method with a fixed current and frequency, the proposed technique can increase the battery heating current by determining the minimum impedance of the lithium-ion batteries. Then, through a variable charging/discharging frequency operation, this technique can increase the heating speed without inducing a temperature plateau because of impedance reduction. A lithium-ion battery with improved self-heating performance at low temperatures was developed and used to verify the proposed self-heating technique. A simulation model and self-heating device (dc/dc converters) were also designed and tested at –30-°C ambient temperature. The proposed frequency-variable resonant self-heating technique achieved a heating speed four times faster (from 2784 s to 717 s) than the conventional self-heating technique. Thus, lithium-ion batteries can be used at cryogenic temperatures (–30 °C) by quickly raising the battery temperature with this technique.