An Improved Feed-Forward Load Compensation Method for Hybrid Energy Storage Systems

Battery-supercapacitor hybrid energy storage systems typically suffer from bus voltage fluctuations under varying loads in electric vehicles. To address this issue, this paper proposes an improved feed-forward load compensation method for hybrid energy management system to suppress voltage fluctuations. First, an active buck-boost topology is considered, where a low-pass filter is applied to allocate load currents for batteries and supercapacitors. Then we design a feed-forward load compensator with the objective of suppressing the DC bus voltage fluctuations. Different from existing studies, the expressions of the compensator and the low-pass filter have been built analytically. NEDC driving cycle is applied to verify the effectiveness of the proposed method. Experimental results show that the proposed load compensator significantly reduces bus voltage fluctuations when compared with conventional methods.