H∞ Control for Battery/Supercapacitor Hybrid Energy Storage System Used in Electric Vehicles

This paper proposes a control strategy of a hybrid energy storage system (HESS) based on simplified 2th-order model. The HESS uses a bidirectional DC/DC converter to connect the supercapacitors (SC) with the battery. Two control objectives, the output current of the SC during the traction procedure and the charging current of the SC while regenerative braking, are regulated by using the DC/DC converter. Two H∞ controllers are designed to control the output and charging current of the SC to their reference values, which are generated by the energy management strategy (EMS). Experimental results show that the proposed control method achieves a satisfactory performance, including a low steady-state tracking error and high response speed when the load power varies in a wide range.