Power-split strategy based on average power method for semi-active hybrid energy storage system in small electric vehicles

In this paper, a simple power-split strategy based on an average power method is proposed for a semi-active hybrid energy storage system (HESS) in small electric vehicles. With the proposed power-split strategy based on the average power method, the supercapacitor (SC) in the semi-active HESS can act as an adaptive power filter. On this basis, the battery only needs to provide the constant/optimal power or compensation power to the motor inverter. Simulation model is established in Matlab/Simulink. Compared to the conventional power-split strategy based on real-time power demand, the operating current/power frequency and the current amplitude of the battery can be improved. In addition, the mode switch frequency of the semi-active HESS can also be improved. The SC can absorb extra output power from the battery or provide the peak power to the load. Therefore, the battery safety can be guaranteed and the battery cycle life can be effectively extended.