Experimental Investigation of Droop Control for Power Sharing of Parallel DC-DC Converters in Voltage and Current Mode Control

This article presents an experimental study that evaluated droop control strategies in DC microgrids with parallel-connected converters. In a decentralized control scheme, it is critical to ensure voltage regulation and load sharing in each converter to maintain a stable operation. Two scenarios are considered: the first involves two converters operating in parallel as voltage mode control, a conventional method discussed in the literature. In the second scenario, a less commonly used method is presented, in which one converter operates in voltage mode control and another operates in current mode control. The proposed decentralized control method is experimentally validated in a DC microgrid using parallel-connected lithium-ion batteries and converters. Load sharing results are examined under conditions with equal droop coefficients, demonstrating equivalent outcomes for specific load steps in both scenarios. However, in the case of different droop coefficients, the alternative method proves to be highly satisfactory, particularly for a broader range of load variations. The results confirm the efficacy of the control method in load sharing and voltage regulation among each converter, as well as the equivalence of control between both scenarios.