A DC-bus voltage control technique for grid-connected AC/DC converters used in smart energy storage units

This paper presents a new voltage control technique for grid-connected single-phase AC/DC converters used in an energy storage power conditioning system. The energy storage unit is intended to be used in a single-phase distributed generation. The proposed control system is able to significantly improve the performance of the closed-loop control system of the converter by using a nonlinear signal processing technique to extract the DC-value of the DC-bus voltage. The proposed technique is able to completely eliminate the impact of double-frequency ripple inherent to single-phase power conditioning systems in the closed-loop control system. Thus, a high bandwidth controller can be used to improve the performance of the voltage control system. Simulation and experimental results demonstrate the superior performance of the proposed closed-loop control system compared to the conventional ones.