Seamless Switching Control for Dual-Source Power in Low-Speed Electrified Railway Service Vehicles

In electrified railway systems, there are sections within the phase-separated areas that lack power supply. Traditional electric locomotives rely on regenerative braking to maintain auxiliary power, which requires higher operating speeds. However, engineering service vehicles generally operate at speeds below 20 km/h, making it difficult to maintain the DC bus voltage through regenerative micro-braking. This can lead to a risk of power loss for traction and auxiliary loads in the phase-separated areas. To address the issue of reliable power supply under low-speed, heavy-load conditions, this paper proposes a seamless switching control strategy based on a dual-source power system consisting of the overhead contact line and a diesel generator. By constructing a hybrid power system topology that integrates a permanent magnet synchronous generator (PMSG), and designing an adaptive excitation control method, the system ensures stable DC bus voltage during the switching process. An automatic over-phase switching process triggered by track magnets enables automated and continuous power supply. A simulation platform based on MATLAB/Simulink is established to verify the system’s performance under typical full-load operating conditions. The results indicate that the voltage fluctuation of the DC bus during the switching process is less than ±4%, and the power supply to both traction and auxiliary loads is continuous, validating the feasibility and engineering applicability of the proposed solution in low-speed phase-separated areas.