Objective As a critical safety guarantee signal for metro train operation, the zero-speed signal is widely used in vital control circuits including traction authorization, vehicle door control, and emergency braking. The zero-speed signal fault may result in failures of key train control circuits, train delays, triggering passenger complaints, all severely impact the normal operation of trains on main lines. Therefore, research on reliable zero-speed signal control is of great necessity.

Method The sources of zero-speed signals and their faults are analyzed, with a focus on their impact on traction authorization, vehicle door control and emergency braking. Furthermore, schemes to optimize the zero-speed signal output circuit and increase redundancy measures for the zero-speed control circuit are explored, as detailed below: installing a power-off delay relay at the zero-speed output source; adopting internal-unit OR logic and inter-unit AND logic for the zero-speed signal braking system; and adopting optimized design approaches for critical control circuits, including staggered arrangement for door zero-speed signals, series-then-parallel topology for traction authorization zero-speed signals, and parallel-then-series topology for emergency braking zero-speed signals. These optimization methods enable reliable zero-speed signal output and effective operation of the train's zero-speed control circuits.

Result & Conclusion  The proposed optimization methods have successfully applied to metro train projects in multiple regions, significantly reduced the probability of train rescue incidents caused by zero-speed signal faults, and improved service quality and operational efficiency, guaranteeing the safe operation of trains effectively.