Design and analysis of a solid state direction relay : Compact Electrical Solution: SiC Relay Module

Sammanfattning

The increasing demands for reliability, longevity, and efficiency in railway signaling systems have driven the need to replace traditional electromechanical components with solid-state alternatives. This thesis explores the feasibility of implementing a Solid-State Direction Relay (SSDR) using Silicon Carbide (SiC) MOSFET technology as a substitute for electromechanical relays in Alstom’s motor control board for railway signaling systems. Electromechanical relays suffer from limitations such as wear and tear, high failure rates, limited temperature range (-40°C to +85°C), and restricted current handling (up to 16A). These factors impact system reliability and increase maintenance costs. The project investigates whether an SSDR can overcome these limitations while maintaining compatibility with existing control logic. The research follows a two-phase approach: Evaluating commercially available solid-state relays (SSR) to determine their limitations regarding current capacity and temperature resistance, and designing and prototyping a custom SSDR solution based on SiC MOSFETs. The proposed relay design addresses key challenges such as insulation between logic and high-voltage sides, power dissipation, thermal management, bistability function, and failure detection mechanisms. The prototype undergoes LTspice simulations, thermal analysis, and PCB design, ensuring compliance with Alstom’s operational and environmental standards. The study concludes that SiC MOSFET-based relays offer significant advantages in durability, switching speed, and reliability, potentially extending the lifetime of railway control systems. The results provide valuable insights for further integration of solid-state technologies into railway infrastructure, reducing long-term maintenance costs and improving operational efficiency.