A Unit Step Direct Model Predictive Control for a Battery/Supercapacitor Hybrid Energy Storage System

This paper proposes a single-step finite control set model predictive controller (FCS-MPC) for current and voltage regulations of a hybrid energy storage system (HESS) in vehicular applications. The HESS consists of a battery pack and a supercapacitor (SC) as the main and secondary energy storage devices, respectively. The voltage and current references to the SC are generated using a rule-based (RB) power split strategy and the vehicle's speed. To implement these references, a single-step FCS-MPC is utilized to ensure that the SC is ready to absorb the braking power or to help the battery pack to boost the power during the acceleration. An adaptive weighting factor algorithm ensures the battery pack's charging current limit is respected. The proposed control algorithm does not require future driving cycle knowledge. The control method is simulated and compared to a reconstructed conventional RB power split strategy with PI current regulator. The results showed a reduced overall battery RMS current, and better SC voltage tracking in urban dynamometer driving schedule (UDDS) cycle.