MOSFET-Oriented Current Sharing Control Strategy for Scalable Parallel DC/DC Converters

Parallel DC/DC converter modules provide a feasible approach for achieving power scalability in various power conversion systems. This paper investigates an MOSFET-based lagging leg series diodes phase-shift full-bridge (LLSD-PSFB) converter and proposes a three-loop current-sharing control strategy for coordinated parallel operation. The strategy incorporates a voltage loop, a current loop, and a current-sharing loop to mitigate load current imbalance caused by MOSFET parameter mismatches and module inconsistencies. The operating principle and parameter design of the single-module LLSD-PSFB converter are analyzed, and an averaged model is established. Based on this model, a small-signal model of the parallel system is derived to evaluate system stability and current-sharing performance. Simulation results demonstrate that the proposed control scheme effectively improves current-sharing accuracy and dynamic response. An experimental prototype is developed to validate the theoretical and simulation results. The experimental results confirm that the proposed three-loop control strategy achieves high current-sharing precision and stable operation, demonstrating its effectiveness for parallel DC/DC converter systems and its potential for scalable high-power applications.