Energy efficient SMPS devices have become crucial in electronic machinery designs

February 21, 2015: With electronic machinery becoming more compact and efficient, SMPS unit manufacturers are facing the challenge of providing continuous technological and design upgradations

By Gunjan Piplani

A Switched Mode Power Supply (SMPS) is a device that converts the available unregulated AC or DC input voltage to a regulated DC output voltage. For example, electricity from the grid is transmitted in the form of AC, while electronic circuits need DC voltage.

The device operates as a regulator when transferring electricity from the mains to the circuits that require well stabilised low level fixed voltages. Moreover, an SMPS also acts as a safety isolator in most applications where the outputs have to be isolated from the input.

SMPSs are used in power handling machines that are switched on and off frequently in order to transfer electric energy via energy storage components (inductors and capacitors). By varying the duty cycle, frequency or a relative phase of these transitions, the average value of the output voltage or current is controlled. The operating frequency range of commercial SMPS units varies typically from 50kHz to several MHz.

Application areas for SMPS units include the machine tool industries, security systems (especially CCTVs), PLC controllers, personal computers and mobile phone chargers.

According to the report ‘AC-DC Power Supplies: Worldwide Forecasts’ submitted by experts from the Darnell Group that’s based in California, USA, the global market for AC-DC power supplies and power converters will grow by an average of 5.6 per cent annually for the next five years, from a turnover of US$ 1.7 billion in 2011 to US$ 2.2 billion in 2016. The sales of new devices for developing power electronics applications are forecast to increase by 18 per cent in 2016, globally.

The report suggests that as a result of the technical and engineering developments in the power electronics field, it will now be possible to achieve the core design objectives of increasing the power density of devices, as well as improving their efficiency and reliability.

What’s new in SMPSs?

This product is absolutely necessary for equipment operating on or transferring electricity. The latest in terms of technology for SMPSs includes better efficiency, modular designs and operating optimally in varied temperature ranges.

Going green: EOS Power has incorporated the ‘no load’ feature in its latest SMPS launches, including the (M)WLP350 and the (M)WLP225 series. This feature ensures that the equipment it is used in is energy efficient.

Sanjay Pusalkar, senior manager, engineering, EOS Power India Pvt Ltd, shares, “With being green becoming a key issue, SMPS units are now equipped with ‘no load’ or ‘standby power’. Efficiency has become a growing concern in recent years, and as is well known, this has led to international power efficiency initiatives, such as the Energy Star programme from the US Environmental Protection Agency (EPA).”

Modular designs that are easy to mount: With machinery becoming more and more compact, the components used in them have also reduced in size. Understanding this phenomenon, Omron has developed technology that uses thermal simulation for the design of its S8VK series, the latest in its SMPS range. The S8VK offers high power density in a compact package. Besides, installing it is easy—all the user has to do is click onto a standard DIN rail using one hand to mount it in a flash. In addition, the S8VK features a double set of DC output terminals (three for the negative terminal), which means less time is spent on wiring.

According to Suvvala Gopi Krishna, director, Emsys Electronics Pvt Ltd, “SMPSs have a wide range of applications. But the latest technology used to manufacture SMPSs is ZVS (Zero Voltage Switching). This reduces the losses in a power supply. SMPSs manufactured using ZVS require smaller sized heat sinks due to low power dissipation, which helps to reduce the size of the power supply.”

Should operate across a wide temperature range: SMPS units these days need to be designed such that they can be used across a wide range of temperatures. The machine designer should keep in mind the external and internal temperatures of the machinery, which vary.

An SMPS unit that can operate in extreme temperatures can be incorporated in electric equipment used in outdoor applications, including CCTVs.

“These SMPS units are also designed keeping in mind the temperature inside the panel, which is higher than the external temperature. Such SMPSs are used in hotter temperature zones,” informs Sameer Gandhi, managing director, Omron Automation India.

Omron’s S8VK range is designed to operate across wide temperature variations. It offers reliable performance in temperatures ranging between -40º Celsius and 70º Celsius, ensuring stable operation in environments where other power supplies may be found lacking.

How to make a purchase decision

Efficiency of the product is key: The product purchase decision should be based on the efficiency of the product. Currently, the benchmark on the efficiency front in India is 93 per cent, which EOS Power’s latest launches measure up to, closely followed by Omron’s latest innovation, which offers 92 per cent efficiency. Nippon’s upgraded Meanwell series offers 91 per cent efficiency.

“Product efficiency is key to the purchase decision, because that’s what defines a product’s capability to convert the power. The higher the efficiency, the lower is the chance of wasting energy during conversion. And the less wastage there is, the lower the electricity rentals. This choice is better made by the machine designer and not the person who simply makes a purchase decision,” says Sameer Gandhi.

Certifications: While choosing SMPS units, certain certifications have become mandatory, which include global certifications like UL, CE certification, etc. Lloyd’s Register (applicable for marine usage) and Safety for Extra Low Voltage (SELV) are some other special case certifications.

Installation: Suvvala Gopi Krishna says, “The user must know if the load is used continuously or not. For example, if the load is continuously used and consumes 12V 3A, then it is better to choose a 12V 5A power supply as it will last for a long period. If the load is not continuous, then choose a power supply that supports the actual need. If the application is crucial, or has many features that change periodically, then follow the operational specifications given by the manufacturer.”

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Nippon India’s MeanWell RST-10000

• 3-phase AC input

• Built-in active PFC function

• High efficiency up to 91 per cent

• Voltage can be trimmed between 20~120 per cent

• Dimensions (L×W×H): 540×424×83.5mm

• Protections: Overload, short circuit, over voltage and over temperature

• Built-in remote ON/OFF control and remote sense function

• Built-in 12V/0.1A auxiliary output for remote control

Omron’s S8VK-T series

• Three-phase power supply with power ratings ranging from 120W to 960W

• Operates under weather conditions ranging from -40º Celsius to 70º Celsius

• The product complies with the standards set by Lloyd’s Register, thus making it suitable for marine applications

• Power boost of 120 per cent

• Efficiency rate up to 92 per cent

EOS Power India’s (M)WLP225

• Packs in 225W of power in 5.08×10.16×2.54cms

• Typically, no-load power consumption is 0.5W

• No minimum load requirement

• Efficiency levels of 94 per cent

• Applicable for medical devices

EOS Power India’s (M)WLP350

• Packs in 350W of power in 7.62×12.7×2.54cms

• No minimum load requirement, has voltage adjustability via an onboard pot

• Efficiency levels of 93 per cent

• Designed to operate with single-phase (3-wire) universal input with a 0.95 or better power factor at a rated continuous output power of up to 350W

• Ideal for medical equipment and factory automation

What users must know prior to a purchase decision

• Know how much power or wattage is required for the load to power up, and the type of connectors needed for it

• Be aware of the peak current required for the load and if the power supply supports it

• Know the continuous load current required, whether the power supply supports it and the efficiency it has

• Understand if the SMPS is designed for open air or enclosed housing

• Check if the input operating range is as needed