DESIGN & PRODUCTS POWER MANAGEMENT
Power supplies for railway applications:
On the rails to 2020
By IPatrick Le Fèvre n a study presented at the international rail exhibition, Innotrans
2016 in Berlin, the European Rail Industry summarized
the state of the business as representing a market size estimated
to reach 185 billion Euro by 2020. For sure, the power
supplies share of that amount is marginal compared to heavy
rolling stock or infrastructure. Though without power supplies,
nothing would be possible and so power designers are actively
engaged in railway modernization. As we approach the next
edition of Innotrans, it is both relevant and interesting to take
a minute to consider the many challenges that power supply
manufacturers are facing in their quest to make railways safer,
coupled with the highest service levels for passengers.
From conservative to progressive
For decades, the railway sector has been an important area
for the power supply industry to develop very specific power
solutions to meet the requirements of this complex market.
The sector consists of three main categories: new equipment,
modernization, and the maintenance and upgrading of
Fig. 1: The range of railway applications is very wide and consists
of a large number of applications requiring simple proximity control
point-of-load (POL) to converters or inverters of several hundred
kilowatts powering the motors of traction engines and other
traction vehicles.
equipment that entered service 10 years ago or more. Each
of these categories represents particular demands on the part
of the developer and requires skills specific to each case.
Although the railway sector is very conservative and priority is
given to reliability and robustness, the new generation of “digital
technology trained” engineers involved in the development of
new rail systems are increasingly integrating digital control and
encouraging the implementation of energy-efficient topologies
such as the Gallium Nitride transistors. In the railway sector this
approach is quite new, requiring more extensive qualification
work during product development, bringing new constraints for
engineers responsible for guaranteeing durable solutions for the
next twenty years. This is a very interesting aspect for design
engineers and a great opportunity to cooperate directly with the
design offices of major railway customers.
From point-of-load to multi kilowatts -
with compliance
The range of railway applications is very wide and consists of
a large number of applications requiring simple proximity voltage
regulators point-of-load (POL) to converters or inverters
of several hundred kilowatts powering the motors of traction
engines and other traction vehicles – see figure 1. In term of
overall railway market, if we exclude the service part of the
segment, rolling stock represents the majority of applications,
followed by infrastructure and finally, track side and signalling.
Each of these sub-segments has its own requirements that are
specific to its environment. For example, converters for vehicle
(e.g. locomotive) startup control, so called Low Battery Voltage
Starter (LBVS) are connected to high voltage catenaries to
deliver a low battery voltage, requiring very high insulation and
high-level safety constraints – see figure 2. In addition, all onboard
equipment must comply with general standards such
as EN50155, which covers electronic equipment used in rolling
stock (a standard that incorporates many other standards such
as EN 50121-3-2 for electromagnetic compatibility). The railway
field is highly standardized and each development begins with
an analysis of the application case and related standards.
In addition to the traditional standards governing operating
quality, operational parameters and safety, after more than 20
years of evaluation and its publication in 2013, this year the
EN45545 standard (resistance and fire behavior) has become
mandatory for all rolling stock. This standard aims to eliminate
the risk of fire during a technical incident and all toxic fumes
resulting from combustion of the product. For power supply
manufacturers, this means selecting components that meet this
standard and carrying out additional tests to ensure full compliance
with the various
chapters of EN45545.
Apart from the large
number of standards,
one of the specificities of
the railway sector is the
fact that many applications
have very specific
requirements in terms of
housings and connectors,
often resulting in products
that are dedicated to a
particular customer. While
the trend is towards the
standardization of card
modules such as DC/
Fig. 3: Standardized DC/DC modules
are reducing time-to-market and
simplifying inventory management and
maintenance.
DC converters shown in figure 3, for more complex products
such as locomotive starter converters or decentralized battery
chargers, the on-demand product remains the norm.
Patrick Le Fèvre is Chief Marketing and Communications
Officer at Powerbox - www.prbx.com
42 News May 2018 @eeNewsEurope www.eenewseurope.com
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