An Improved Droop Control Method for Full-Load-Range Current Sharing in Multi-Stack Fuel Cell Systems

In multi-stack fuel cell systems (MFCS), current sharing is crucial for maintaining operational consistency and reliability. However, uneven line resistances often lead to unbalanced output currents among paralleled stacks. Droop control offers an effective means to achieve current sharing without communication links. Traditional linear droop control tends to cause significant bus voltage deviation and exhibits poor current sharing accuracy under heavy-load conditions. Although typical nonlinear droop methods improve performance in heavy load with reduced voltage drop, they suffer from degraded current sharing accuracy in light-load regions. To address these limitations, this paper proposes an improved droop control method that synergistically combines linear and nonlinear droop characteristics. Simulation results of the MFCS validate that the proposed approach maintains high current sharing accuracy across the entire load spectrum while minimizing bus voltage variation.