Frequency varying heating strategy for lithium-ion battery rapid preheating under subzero temperature considering the limitation of on-board current

The electrical performance of lithium-ion battery gradually deteriorates with the temperature decrease. Alternating current (AC) heating is an efficient manner to improve the lithium-ion battery (LIB) discharge ability at low temperature. This paper proposes an effective method to quickly preheat battery under low temperature based on sinusoidal AC. An electrothermal coupled model is established to precisely characterize the battery electrical and thermal behavior characteristics. Subsequently, the impedance characteristics of large format prismatic LIB are investigated through electrochemical impedance spectroscopy testing. The amplitude and frequency of sine wave current exploited for battery pack heating are optimized at different temperatures and SOC based on the analysis of AC impedance. Finally, the sinusoidal AC heating for battery pack is achieved leveraging the designed full bridge inverter circuit-based heater and the heating efficiency with respect to different amplitudes and frequencies are comprehensively compared. On this basis, a frequency varying heating strategy with fixed amplitude considering the current limitation of hardware circuit is proposed. The experimental results show that the battery pack can be rapidly heated from −30 °C to 0 °C with the maximum average temperature rise rate of 3.78 °C/min, and the heating energy consumption rate is less than 0.27% SOC/°C with the proposed strategy. On this account, the battery pack discharge capacity under frigid environment can be distinctly enhanced based on the proposed heating strategy.