Hybrid Droop-Based Control for Parallel Operation of DC-DC Converters in a DC Microgrid

Connecting multiple converters in parallel to meet load demands in a DC microgrid leads to power sharing and circulating current issues. These issues are due to mismatches in the cables that connect the parallel converters to the load bus. Conventional droop control methods lack good dynamic performance and power sharing accuracy, requiring advanced methods to overcome these issues. This paper proposes a hybrid droop control strategy that uses an adaptive integral-based controller to improve the dynamic performance and overcome the power sharing issue. In this method, a correction term is integrated with the conventional droop method using the adaptive controller, which dynamically adjusts the reference voltage using only local measurements and a single data point over a low-bandwidth communication link. In addition, a delay compensation method is introduced to address the impacts of communication delay. The proposed controller combined with delay compensation reduces the settling time and overshoot in the current waveform. In addition, the impact of power sharing on circulating current is analyzed mathematically, and a solution is provided to reduce the circulating current. The proposed method is simple in design and easy to implement. Simulation and experimental studies validate the effectiveness of the proposed method.