Deadbeat Control for Hybrid Energy Storage Systems in DC Microgrids

This paper presents a simple and effective deadbeat-based method for hybrid energy storage systems, including batteries and supercapacitors, in dc microgrids. Inheriting from the nature of deadbeat control strategies, the proposed method can generate the optimal duty ratio in one control cycle, so that it can respond faster to the disturbance than various proportional-integral-based methods in previous works. With an appropriate reference assignment based on the characteristics of batteries and supercapacitors, this method can compensate the transient and steady-state power mismatches in dc microgrids while maintaining an excellent dc bus voltage regulation. Specifically, the high power density feature of the supercapacitor is fully utilized by the proposed method, and the burden on the battery can be relieved for a longer lifespan. A current observer is employed in the proposed method to eliminate the requirement of photovoltaic (PV) and load current sensors to reduce the system cost. A laboratorial setup of a dc microgrid, including the HESS and PV emulator, is built to validate the effectiveness of the proposed deadbeat-based method under various varying conditions in load power consumption, PV power generation, and bus voltage reference. The performance of the proposed method is compared with that of the previous works to show its superiority in dynamic and steady-state responses.