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

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.