Investigation of Short-Circuit Characteristics in Marine DC/DC Converters

The ship’s DC integrated power system is central to onboard propulsion and electrical supply. Its stability and reliability are crucial for safe vessel operation, as DC short-circuit faults can rapidly damage equipment. Existing equivalent models for DC/DC converter short-circuits, however, fail to accommodate varying fault-transition resistances and overlook the duty cycle’s ability to regulate short-circuit current, leading to inaccuracies in fault-characteristic analyses. This paper investigates the short-circuit behavior of DC/DC converters and provides a theoretical basis for fuse coordination by constructing a MATLAB/Simulink equivalent model. It also analyzes the effects of transition resistance and duty cycle on short-circuit current. A state-space averaged mathematical model under short-circuit conditions is derived and simulated. Additionally, the influence of parasitic parameters (such as capacitor ESR and ESL) is examined. Simulation results indicate that as transition resistance increases from 0.01 mΩ to 1 Ω, the mathematical model remains highly adaptable with an error margin below 5%. This model outperforms the equivalent model in accuracy, while the effects of capacitor ESR and ESL on short-circuit current are minimal.