Double adaptive power allocation strategy in electric vehicles with battery/supercapacitor hybrid energy storage system

Abstract

This paper proposes a new energy management strategy (EMS) for electric vehicles (EVs) with battery/supercapacitor hybrid energy storage systems (HESS). Firstly, the battery/supercapacitor HESS configuration and obtaining the load current from the driving cycle are comprehensively explained. Secondly, fixed and adaptive frequency-based (AFB) EMS are discussed in detail. In the proposed method, the current demanded by the load is separated into low and high-frequency components with the help of an adaptive low-pass filter (A-LPF). In addition, adaptive battery current (ABC) is generated according to the supercapacitor (SC) state of charge (SoC), and a double adaptive power allocation strategy is performed. The proposed method is compared with the AFB-EMS for load currents, load powers, DC link voltages, filter cut-off frequencies, battery, and SC SoCs on the UDDS driving cycle. When the obtained results were evaluated together, it was observed that the proposed method completed the driving cycle with a higher battery SoC and realized the adaptive cut-off frequency in a narrower band.