Bel Fuse
Bel Fuse
The Future of Railway Power Conversion – The RCM500E
This article first appeared in the Railway-News Magazine Issue 4 2024.
Introduction
Power conversion in railway applications forms a critical component in power distribution and safety, ensuring that energy is efficiently transformed and managed to support various onboard systems.
Choosing the right partner for power conversion equipment can significantly benefit engineers by ensuring reliability and performance enhancements, while maintaining an edge with the latest innovations. Bel’s next generation of DC-DC converter under the Melcher brand, the RCM500E, does just that. Using modern technologies and manufacturing, this converter delivers all the same rugged and efficient design expected of the Melcher brand, while significantly reducing cost and form factor. This article investigates the design and innovations inside the latest railway DC-DC converters.
The Challenges of DC-DC Conversion
The challenges faced by DC-DC converters are well documented, and yet, the need for their use remains constant. Some of the biggest challenges faced by DCDC converters by far are the tradeoffs between size and efficiency.
The size of reactive components, such as transformers and capacitors, are all frequency-dependent and shrink with increasing frequency. However, switching losses go up with frequency, lowering efficiency and giving designers a choice between designing a small converter or an efficient converter. At the same time low efficiency means more thermal management, which can negate any power density gains from increased frequency.
The high-frequency make/break of inductive currents through transformers can also induce large voltage spikes which can damage components. This is often compensated for with larger, less efficient switches and makes them more expensive. These spikes can also lead to EMI and require additional large magnetic filtering components to mitigate. All of this can make a DC-DC supply larger and heavier, which can negatively affect an application with physical constraints.
A lot of research has gone into developing new methods and topologies that can limit switching losses, enable higher switching frequencies and reduce form factors.
