Phased control reciprocating airflow cooling strategy for a battery module considering stage of charge and state of health inconsistency

Abstract

The thermal management of lithium-ion batteries has attracted attention in the field of electric vehicles (EVs) and hybrid electric vehicles (HEVs). However, the batteries are usually connected in series and parallel to build a battery module or pack, and the consistencies in state of charge (SOC) and state of health (SOH) during the service life affect both the performance and thermal safety. Therefore, this paper proposes a phased control reciprocating airflow cooling strategy for battery modules considering SOC and SOH inconsistencies. The electric and thermal models of a single battery and module are established, and the SOC and SOH of the batteries in the module are obtained by the recursive least square-dual extended Kalman filter (RLS-DEKF) algorithm. Furthermore, the heat generation rate of batteries in the module is estimated according to the SOC and SOH estimation and voltage measurement results. Finally, a phased control reciprocating airflow cooling strategy is proposed according to the estimated heat generation rate of batteries in the module, in which the flow direction of the cooling airflow is periodically reversed. The proposed cooling strategy is verified with the worst case of consistency. Compared with the unidirectional cooling strategy, the maximum temperature and maximum temperature difference of the SOC-inconsistent battery module under the phased control reciprocating airflow cooling strategy are reduced by 11 % and 42 %, respectively, and those for the SOH-inconsistent battery module are reduced by 4 % and 32 %, respectively.