Design of a Relay-Free Driving Module for DC Signal Machines in Distributed Railway Systems

The centralized control architecture for railway signal drivers often experiences unstable supply voltage and insufficient drive current due to the extended length of signal cables. Furthermore, the high inrush currents during the operation of conventional electromechanical relays can damage signal machines and reduce their service life. To address these issues, this paper presents a relay-free drive module for DC signal machines based on a distributed system. The module integrates remote communication and safety control technologies, enabling the deployment of safety execution units trackside. It utilizes power-driven DC-DC conversion technology, replacing relay-based control circuits to ensure safe driving of DC signals. Based on the "fail-safe"principle, the module incorporates circuit self-testing and closed-loop drive control to guarantee secure and reliable operation. The intelligent control core employs a heterogeneous dual-channel (2oo2) architecture using System-on-Chip (SoC) technology to enhance security and mitigate common-cause failures. Experimental verification confirms that the proposed module delivers highly stable and programmable DC output voltage across a wide input range, demonstrating excellent voltage regulation and controllability via Pulse Width Modulation (PWM). The all-electronic design eliminates contact arcing and inrush current, while integrated real-time monitoring and self-diagnostic capabilities ensure operational safety and reliability. These results underscore the module's strong potential for practical application in modern distributed trackside control systems, offering advantages in system simplification, maintenance reduction, and enhanced equipment longevity.