A Self-heating and Charging Coordinated Strategy for Low-temperature Lithium-ion Batteries based on a Novel DAB-LC Converter

The charging capability of lithium-ion batteries (LiBs) is inherently limited at low temperatures, resulting in less charging current rates. In this regard, preheating LiBs before charging has been suggested as a solution, however, this requires separate control and additional switching mechanisms. Moreover, this approach cannot simultaneously produce alternating current (AC) and direct current (DC), resulting in reduced charging efficiencies. To overcome these challenges, this research proposes a self-heating and charging coordinated strategy. Furthermore, we propose a dual-active-bridge LC (DAB-LC) converter designed to facilitate simultaneous AC and DC output. A dual-closed-loop controller ensures that the converter can output the maximum acceptable DC of LiBs at the current temperature and state of charge (SOC) and superimposes adaptive AC within the battery safety threshold, thereby substantially enhancing the charging speed. Experimental results demonstrate that the proposed strategy can charge LiBs to 80% SOC in 1.55 h at -10°C, which is 6.65-times faster than the conventional little-current charging method.