A fast pre-heating method for lithium-ion batteries by wireless energy transfer at low temperatures

- Lithium-ion batteries (LIBs) are required to be preheated at low temperatures in advance to ensure their normal operation. Alternating current (AC) heating is an effective heating method with little damage to the batteries. This study develops a new method to obtain onboard AC power by improving the wireless charging system based on the inductance and double capacitances-series compensation topology, which heats the battery by high-frequency AC on the secondary side of the wireless charging system. Heating experiments of a single cell under different frequencies, states of charge and current amplitudes and the battery packs with different numbers of battery cells in series were conducted. Experimental results indicate that this method can heat the battery from −20 °C to 0 °C in 142s at an root mean square value of 3C and an average heating rate of about 8.5 °C/min with 85 kHz AC. The proposed heating system can provide fast heating of LIBs for electric vehicles.