Pre-heating Method Employing Pulse Current Excitation for Effective Charging of LiB in Low-Temperature Environment

The charging efficiency of lithium-ion batteries becomes significantly low in the cold environment since its impedance increases while its capacity reduces. To enhance the charging efficiency, the lithium-ion battery (LiB) pack must be pre-heated before every fast-charging process. The conventional methods utilize the external heater or the existing equalizer to heat the LiB pack based on the energy dissipation scheme, but the processing time is longer. This paper proposes a rapid internal pre-heating method to heat the LiB pack by using the pulsed-current (PC) driving scheme, which can be embedded into the existing charger. A thermal model of the heating process under the pulsed-current driving is introduced in order to re-enact the process. The performance of the proposed method is verified by various test scenarios on the Matlab/Simulink platform. The proposed method can increase the battery temperature from -20 °C to 0 °C after 30s and to 25 °C after 376s, respectively. The proposed method can be implemented directly by the existing system without any additional circuit.