In this paper, we explore the power supply requirements and classifications of rail transit vehicle equipment. We analyze the standards outlined in EN50155-2007 for in-vehicle electronic systems and provide detailed guidelines for selecting DC/DC converters. These include isolation requirements, input voltage ranges, operating temperature limits, and essential performance characteristics. Finally, we offer a practical guide for choosing isolated DC/DC power modules to ensure reliable operation in rail applications.
As one of the countries with the largest high-speed rail network in the world, China has set ambitious targets during its 13th Five-Year Plan (2016–2020). By 2020, the country aimed to expand its total railway network to 150,000 kilometers, with high-speed railways reaching 30,000 kilometers. This represents an increase of 29,000 kilometers overall, with 11,000 kilometers added to the high-speed rail system. The investment in high-speed rail during this period is expected to exceed 4 trillion yuan, while the locomotive sector will see around 800 billion yuan in funding.
Internationally, China’s high-speed rail projects have made significant progress. Construction has begun on the Jakarta-Bandung High-Speed Railway in Indonesia, as well as the China-Laos Railway. In Serbia and Hungary, sections of the Sino-Thai and Hungarian railways are under development, and the Moscow-Kazan High-Speed Railway in Russia has been officially confirmed. Railways have become a symbol of China's technological advancement, playing a key role in the "Belt and Road" initiative. Developing countries like India also present substantial opportunities for future railway expansion.
The integration of automotive electronics in rail systems has increased significantly due to the need for improved reliability and passenger comfort. Most in-vehicle electronic devices are powered by the auxiliary power supply system, which includes the battery and other non-traction loads. Under normal conditions, the charger provides low-voltage bus power, while the battery system supports critical functions such as the Train Control and Management System (TCMS) and lighting. It also acts as an energy buffer in case of charger failure.
Vehicle electronics typically consist of systems like TCMS, signaling, passenger information, and air conditioning control. To ensure reliable operation, each subsystem must be isolated to prevent faults from spreading. Many devices communicate via a train communication bus, allowing the driver to control various systems remotely through the onboard controller. The growing use of intelligent technologies increases the demand for isolated power supplies.
In-vehicle electronic devices must meet strict standards, including EN50155, to ensure they operate reliably in harsh railway environments. Key requirements include environmental resilience (temperature, humidity, vibration), electrical isolation, surge protection, electromagnetic compatibility (EMC), and long-term reliability. For example, devices must withstand surges up to 1.4 times the nominal voltage and pass rigorous EMC tests. Reliability testing often involves simulating extreme conditions over extended periods.
When selecting power supplies for rail applications, several factors must be considered. Shock and vibration resistance is crucial, as railway vehicles experience constant movement. Potting techniques can enhance the mechanical stability of power modules. Input voltage ranges must accommodate fluctuations caused by auxiliary equipment or inductive loads. Isolation requirements depend on the battery voltage, with higher voltages necessitating stronger dielectric strength. Temperature and humidity resistance is also essential, especially for long-distance trains operating in diverse climates.
Special surge protection measures are required to handle transient overvoltages, which vary by region. For instance, British standards specify that equipment must tolerate two types of surge waveforms. Active clamp circuits are often used to manage these surges effectively. Additionally, power interruption and drop requirements may necessitate the use of larger capacitors to maintain stable operation.
In conclusion, this paper provides a comprehensive analysis of in-vehicle electronic equipment requirements and offers practical guidance for selecting DC/DC isolated power modules. These insights are vital for ensuring the reliable and safe operation of railway power systems.
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