Converters, also known as switch mode power supplies (SMPS), convert the alternating current (AC) from the mains to a direct current (DC), and are used in a wide variety of applications, such as controlling DC motors for household or industrial use (machinery). The power range of these converters is from a few milliwatts (as in a mobile phone) to hundreds of megawatts (in a HVDC transmission system). These AC-DC or DC-DC converters provide regulated DC power to a circuit. The output can be either single or multiple, and of different voltage and current ratings. Most modern electronic devices often demand different voltages to function; therefore, modern power supplies also contain one or more DC-DC converters. A DC-DC converter changes one DC voltage level to another, higher or lower DC voltage level, and is used with a power supply to prevent the need for a second AC-DC supply.
By Sandhya Malhotra
Friday, March 11, 2011: The growing demand for modern high performance applications, as well as the increasing use of a clean power supply with stringent power efficacy, is growing rapidly in the industrial, telecom and medical segments. These needs are giving rise to a growing demand for converters. According to industry experts, the total market size of AC-DC as well as DC-DC converters in India is approximately Rs 8-10 billion, including the market for battery chargers and other DC power supplies.
Application areas
Power electronic systems are found in virtually every electronic device. DC-DC converters are used in most mobile devices to maintain the voltage at a fixed value, whatever the voltage level of the battery is. These converters are also used for electronic isolation and power factor correction, whereas AC/DC converters are used every time an electronic device is connected to the mains. These converters may simply change AC to DC or can also change the voltage level as part of their operation.
According to Mathew Philip, business development manager, TDK, Lambda Singapore Pte Ltd (India), the major application areas driving the demand for converters are telecom, automation, medical electronics, computers, process instrumentation, railways, industrial controls and data acquisition systems, among others.
What companies are offering
The converter market is predominantly flooded with international companies such as TDK Lambda, Murata Power Solutions, Mornsun Power, Minmax Technologies and RECOM Power Solutions, that operate in India through their distributors. There are also a few manufacturers in India like Powercube, Gallant Electronics Controls and Span Controls.
Minmax is a leading provider of DC-DC converters and AC-DC power modules. “All our products are lead-free and fully RoHS compliant. The DC-DC converters are available in a wide range of more than 1000 standard models with 1 to 40 watts of output power, and in a variety of package configurations like SMD, DIP or SIP. The AC-DC power modules come in the 1 to 60 watt range of output power and are used in PCB and chassis mounting,” says P Anand, regional sales and marketing manager, Unified Electro-Tech Ltd, the sole distributor for Taiwan based Minmax Technology Pvt Ltd.
TDK Lambda offers AC-DC and DC- DC converters, DC-DC power modules, LED drivers, DC programmable power supplies and line filters. “Our AC-DC converters are available in a wide input range, with safety and EMI/EMC approvals. The DC-DC converters have an input range covering 5V, 12V, 24V, 48V, 110V and 280V, and power modules are available in full brick, half brick, quarter brick, eighth brick and sixteenth brick variants,” explains Philip.
Murata Power Solutions has extended its HPQ range of high power quarter brick isolated DC-DC converters with the introduction of the HPQ-12/25-D48, a 300W model with 12V output. The new model features a wide 2:1 input range of 36V to 75V and output of 12V, plus a high output current of up to 25A. It boasts of a high efficiency of up to 94.5 per cent.
Technological innovations
Converters have been undergoing many technological innovations. The new types of converters available are digitally controlled power supplies with improved performance, smaller sizes and with peak power capability. Converters are now available with single output power supplies and with front end power supplies.
In modern systems, the conversion is performed with semiconductor switching devices such as diodes, thyristors and transistors. Evidence of this can be seen in the complexity of today’s electronics applications, which use an increasing number of voltage rails, making multiple output power supplies impractical in many devices. This can be seen in applications ranging from personal computers and plasma TVs to servers and Ethernet switches.
“High end devices present even more opportunities for the use of converters, as modern telecommunications and data communications are deploying AC front ends as the primary means of converting AC mains voltage to the more usable voltages required by logic devices, auxiliary/peripheral devices and DC-DC converters,” explains Rajendra N Gajendragadkar, CEO, Powercube.
Adds Philip, “The emergence of LED lighting as a major application area is another instance where single output power supplies will have a strong positive impact on the market. High power LEDs used in small displays and in mainstream lighting applications require power levels of 100W or more. At the same time, demand for lower wattage LED power supplies will also remain strong. Given this increasing demand for LED lighting applications, a growing number of companies are introducing AC-DC power supplies designed exclusively for high brightness LED lighting applications.”
“Digital power conversion has become a mainstream technology and is being used as a source of product differentiation by more and more makers of AC-DC power supplies. Digitally controlled architectures for power conversion and power management have emerged as an accepted technology,” says Anand. Used primarily in higher end applications, digital power has created a number of new design opportunities. Digital power is also more efficient in applications featuring power factor correction, as these applications often require voltage and current profiling and are better implemented in digital rather than in analogue systems.
Power electronic converters are linked to new soft switching techniques that enable efficient operation at high switching frequencies, thereby permitting the miniaturisation of transformer and filter components. The work also embraces new fabrication methods for power converters and magnetic components. “The footprint of converters is shrinking due to use of higher switching frequencies, use of surface mount components and technology advances in magnetics. In view of the concerns over line pollution due to EMI, more and more AC-DC converters are employing a PFC front end,” informs Gajendragadkar.
Buying tips
Whether one obtains converters from a manufacturer or distributor, there are some issues to be considered before making the purchase. Listed below are some guidelines that will help you to make the right choice
- The majority of buyers in India demand low cost products while ignoring the most important point — that converter failure would result in failure of other products. Hence, converters should be of good quality
- Today, many companies with inadequate expertise in power supply design are in the market. They sell at dirt cheap prices and provide no post sales support, claiming the product’s failure was due to bad input supply. Hence, customers should buy from authorised distributors
- While choosing a power supply vendor, the buyer should look at the professional standing of the potential vendor and check whether the product’s features match up to the declared data
- One should thoroughly test samples to verify published product specifications for at least 100 hours continuously, before placing bulk orders
- Before buying, one should check if the converters have features like a wide input range, good line and load regulation, low ripple, and noise and standard protection against over voltage, overload and short circuits
- Selecting the best isolated brick DC/DC converter for an application can be a challenging task for customers. Factors that influence the purchase will be transient response, efficiency, environmental conditions or mechanical packaging
Source: Powercube
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