Adaptive power allocation using artificial potential field with compensator for hybrid energy storage systems in electric vehicles

Abstract

This paper proposes an adaptive power allocation strategy using artificial potential field with a compensator for hybrid energy storage systems in electric vehicles. In the power allocation level, a potential field is constructed to guarantee the state-of-charge limitations of supercapacitors. Virtual forces of this field are mapped as the allocation ratio of load power. The cutoff frequency is obtained by cutting the real-time load spectrum with the allocation ratio. In the control level, a feed-forward compensator is designed to compensate for load variations in advance which can counteract dc-link fluctuations. Experimental tests under different supercapacitor initial state-of-charges and different driving cycles evaluate the superiority of proposed methods. The artificial potential field strategy provides lower battery capacity loss with supercapacitors state-of-charge limitations guaranteed compared with existing real-time power allocation strategies, e.g., a more than 15% reduction of battery capacity loss in the urban driving cycle. The feed-forward compensator allows the hybrid energy output to meet the load requirements better.