DC-DC converters in railroad applications

Electronic systems are an important aspect of railroad rolling stock, affecting the comfort and safety of passengers, while at the same time providing the operator with full control over electronic components and equipment on board the rail vehicle.

The emphasis on automation and high performance of such systems is a result of rapidly developing technologies and the requirements of passengers themselves. Among the railroad systems we can distinguish, for example:

• Train Control and Management System – TCMS;
• Passenger Information System – PIS;
• Automatic Train Control system – ATC;
• Radio communication system;
• Lighting system;
• AC and heating system;
• Braking system.

Suitably matched current directly from the overhead line, redundant low voltage power supply or battery power are mostly used to power the auxiliary systems of rail vehicles.

How to match the current to the electronic systems of railroad vehicles?

DC-DC converters come to our air. These are electrical or electromechanical devices that convert direct current of specific parameters into direct current of other parameters. Converters are mostly used in power systems that cannot be fed directly to the receiver. The current passed through such a converter is appropriately increased or decreased.

We distinguish between the following DC-DC converters:

• Voltage polarity inverting converters;
• Step-up converters;
• Step-down converters;
• Buck-boost converters.

The latest solutions are using advanced DC-DC converters, whose operation can be continuously adapted to current needs.

What requirements must inverters for the railroad industry meet?

All electrical and electronic equipment must comply with certain standards in order to operate in railroad rolling stock. EN 50155 is a standard that specifies requirements for electronic equipment used in the railroad industry, including:

• Electrical requirements - voltage range, insulation strength, resistance to surges, overloads, electrostatic discharges and blackouts;
• EMC requirements - protection against electromagnetic interference;
• Environmental requirements - operating temperature, humidity level, IP and IK protection, shock and vibration resistance;
• Requirements defining the life cycle of the device and the way it should be used. 

EN 50155 compliant inverters are used in:

• In traction systems;
• In vehicle power and communication systems;
• Military and telecommunications applications;
• In equipment with difficult operating conditions.