e Power
AC-DC & DC-DC Converters
Heart of Electronics system
Mathew Philip | Manager
TDK Lambda
AC-DC Converters and DCDC Converters are used to
converter a AC Input supply
or a DC Input supply
respectively to a required DC
out put. They are used in
various application as it is
considered as the heart of
any electrical or Electronics
system.
The applications where it is
used includes Medical
equipment’s, Factory
automation, Building
automations, Process control
systems, Signage displays,
Telecommunication
equipment’s, Renewable
energy, Test and Measuring
equipment’s, Defence and
Aerospace, Transportation
systems etc.
The usage of these converters in the
applications requires careful consideration
of the operating conditions, environment
and power loads. It is advised to ensure
the converter is not being continually
stressed. When selecting a converter
beware of the pitfalls in over and under
specifying the requirement. For example if
the system requires a 100w of DC power ,
it would be unwise to select a power
supply that is exactly rated for 100w
because the converter would be operating
at 100% of its capacity thereby stressing
the electronic components and will likely
fail prior to or very shortly after the
warranty period. It is hence very
important to choose a converter vendor
that employs conservative component
deratings in the design of their converter.
This means they design their converter
circuit so that components such as
semiconductors, capacitors, inductors etc.
are never stressed to their maximum
ratings. Sadly many converter vendors that
sell low cost products often design their
product such that the internal
components are working at their
maximum ratings. TDK-Lambda gives more
importance to selection of the
components such that reliability and
quality of the products is ensured and
provides a low cost of ownership.
Operating conditions:
Sometime a low cost converter is selected
for applications that require 24/7
operation. Low cost converter
construction employs low cost
components (capacitors, active
ELE Times | 28 | November, 2016
components, fans etc.) that are unsuited
for constant operation. The best solution
for 24/7 application is to find an industrial
grade converter that includes a 5 year or
longer warranty. The warranty period is a
good indication of the type of components
used on the converter construction
Environment - Ambient temperature:
One of the biggest killer of a converter is
heat. Since all converters generate Heat
due to their inherent inefficiencies they
require cooling by conduction via heat
sink, natural air or forced air cooling.
However, whichever cooling method is
employed, due consideration to prevailing
ambient air temperature range must be
included on the end equipment design.
When Fan cooled converter are employed
in corrosive or dusty environment a
scheduled maintenance program must be
established to periodically clean air filters
and replace fans. In this condition it is
wise to consider non fan cooled
converters that are cooled vis. conduction
or natural airflow.
Power Loads:
Many times industrial and control
equipment include DC motors, solenoids,
etc and these loads typically have a peak
start-up current that exceeds their steady
state current. The system designer can
select a converter that handles peak
current.
The usage of AC-DC or DC-DC converters is
becoming ever more widespread and in
some of the applications where it is used,
has semiconductor devices which must