Current-Sharing Control Method for Parallel LLC Resonant Converters

In sectors such as more electric aircraft and electric vehicles, the requirement for DC power is escalating, leading to heightened interest in DC-DC converters. LLC resonant converters, noted for their high efficiency and power density, are extensively employed within these fields. To satisfy the demands for high power output, multiple LLC converters are frequently connected in parallel. However, parameter mismatches between modules in a parallel system inevitably result in current imbalance issues. This paper proposes two current-sharing control strategies for parallel systems to mitigate this issue. During the soft-start phase, current compensation is incorporated into the traditional phase-shift soft-start technique to facilitate current sharing. In the steady-state operating phase, current sharing is achieved via adaptive droop control. The proposed current-sharing control strategies diminish the risk of overload for individual converters and enhance power conversion efficiency. The effectiveness of these proposed control methods is confirmed through extensive simulation experiments.