AC-DC & DC-DC Converters Heart of Electronics system


AC-DC Converters and DC-DC 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.

Mathew Philip, Manager, TDK Lambda
Mathew Philip, Manager, TDK Lambda

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 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 operate at low voltages while handling large currents and supporting high speed operation. This is realized by positioning converters in close proximity to load devices and hence a technique known as Distributed Power Architecture (DPA). TDK-Lambda offers a broad line up in this area. The products suitable for DPA system include front-end power supplies, bus converters and Point of Load (POL).

The features of DPA: It supports more compact and more efficient systems, lower operation voltages, higher currents, higher response speed of semiconductor devices and Digital control. An example of DPA system is shown in the picture below:
Front end power converters are that convert AC Source or a DC source which can be of low voltage or high voltage to core required DC voltage. Bus converters are isolated converters that converts the core voltage to the intermediate voltage required by subsequent stage POL (Point of load). POL is a High efficiency, fast response dc-dc converter that is placed close to the load and converts the intermediate voltage into the voltage required by semiconductor devices.


Some of the interesting applications of TDK-Lambda Power supplies

A) Sonar Application
Sonar systems installed on surface ships, sonar is also fitted extensively on submarines and other submersible vessels. Navigation underwater is usually calculated using the vessel’s distance travelled and direction, but this does not identify the position of other submarines or the existence of a drilling rig. As radar cannot be used below the surface, sonar is the alternative.TDK-Lambda’s compact Z+ programmable power supplies are now being used in sonar systems on submersibles due to their proven reliability

B) Process control
TDK-Lambda HWS series / DRF series is widely used in distribution control system as these offers relay contact and Class1 Div2 certification especially to be used in harsh environment. Optional conformal coated PCB available to use in harsh/humid environment

C) Automotive Instrument cluster test Jig
Automotive Instrument Clusters undergo a demanding test regime to ensure high reliability. A manufacturer that assembles and tests these units is now using the TDK-Lambda Z+ programmable DC power supply on its test rig

D) UHF/VHF Radio
Baseplate cooled PFE500SA AC-DC power modules are used in a number of deployable equipment applications around the world. The need for rugged and dependable operation is paramount. A manufacturer of UHF/VHF radios designed in the 28V version of the PFE500SA for their integral power source, because of proven field reliability and technical support.

E) LED Video Display
Advertising has been radically changed with the extensive use of eye catching LED video displays. These signs are often positioned outside and the reliability of power supplies is one essential factor for manufacturers. TDK-Lambda’s converters are used in high profile displays because of their specification, and the availability of printed circuit board coating to avoid failures due to condensation or humidity.

F) Renewable Energy – Micro Grid
The 2500W ,EZA2500-32048, bidirectional DC-DC converter is ideal for solar or wind powered energy storage systems. This power supply can automatically, and continuously, change conversion direction from “grid side” 320Vdc nominal to “battery side” 48Vdc nominal. The EZA2500 is also designed to be used for energy recovery; recycling previously wasted power from battery testers, robots, cranes, elevators and autonomous ground vehicles. When a 300 to 380 high voltage dc source is available, for example from solar panels during daytime, the converter can be programmed to charge 48Vdc rechargeable lithium-ion battery banks. At night the stored energy can then be converted back to high voltage dc to power either DC-AC inverters or dc-input electrical/electronic devices.