Reduced chip sizes and the increasing constant pressure per watt of lumens is forcing LED chip manufacturers to retrofit LED drivers that come with the latest technology. These drivers are highly efficient and have built-in protection.
By Baishakhi Dutta
Most of us are now familiar with the long life and energy saving aspects of LEDs. But very few are aware that these innovative light sources require an LED driver (also known as the LED power supply) for operation, which is similar to the ballasts for fluorescent lamps. LEDs require drivers for two purposes:
- The LEDs are designed to operate at a low voltage (12V-24V DC). However, most places offer higher voltages (120V-277V AC). LED drivers convert a higher voltage, alternating current into low voltage, direct current.
- The LED driver also protects the LED from voltage or current fluctuations. A change in voltage can cause a change in the current supplied to the LED. Its light output is proportional to its current supply, and the LED is rated to operate within a specific current range (measured in amps). Therefore, due to the higher temperature within the LED, too much or too little current can cause the light output to change or decrease more quickly.
Next-generation LED lighting requires new technologies and solutions to meet the changing industry demands. Emerging trends in the LED driver industry include the development of visible light communication (VLC) LED drivers and of colour-adjustable drivers.
Types of LED drivers
There are two main types of external LED drivers—constant current and constant voltage, and a third type called an AC LED driver, which will also be discussed here. Each type of driver is designed to operate LEDs with different electrical requirements. When replacing a driver, the input/output requirements of the old driver must match that of the new one as far as possible. The key differences between the main types of drivers are listed below.
- Constant current drivers: Constant current drivers power LEDs that require a fixed output current and a range of output voltages. There is only one specified output current, labelled in amperes or mA, and a series of voltages that vary depending on the LED load (wattage).
- Constant voltage drivers: Constant voltage drivers power LEDs that require a fixed output voltage and maximum output current. In these LEDs, the current in the LED module has been regulated by a simple resistor or internal constant current driver. These LEDs require a stable voltage, typically 12V DC or 24V DC.
- AC LED drivers: AC LED drivers are actually minimum load transformers, which means they can technically operate low voltage halogen or incandescent bulbs. However, LEDs cannot work with conventional transformers because these cannot detect low wattage LEDs.
AC LED drivers are typically used with light bulbs that already contain an internal driver, which converts current from AC to DC. So the function of the AC LED driver is to lower the voltage to meet the voltage requirements of the bulb, typically 12V or 24V. AC LED drivers are generally used to power 12V-24V AC input LED MR16 bulbs, but they can be used with any 12V-24V AC input LED bulb too.
Miniaturised LED drivers
LED technology has revolutionised the lighting market on many counts—efficiency, form factor, longevity and controllability, and continues to offer new lighting solutions. LED drivers have improved and been optimised over the past decade, but the basic problem is that power conversion technology has remained largely unchanged since the introduction of switch mode power supplies in the 1970s.
In terms of size, life and control, LEDs have surpassed the drivers that power them. One way to narrow this gap is to dramatically increase the switching frequency. The idea is not new, but the possibility of doing so in a commercially viable way is. The technique of increasing the switching frequency reduces the size of the passive energy storage component. Therefore, it reduces the size, weight and hence the cost of the LED driver, while improving its reliability and life.
The latest technology
Since LEDs have different power ratings, drivers must generate different constant currents to run them. Sudhakar Poul, CEO, RB Eco Power LLP confirms that customers usually demand inbuilt surge protection for the drivers. For homes and offices, the most suitable will be 6kV (kilovolt), and for outdoor applications like streetlights and floodlights as well as industrial applications, it should be 10kV. In its products that use the latest technology, RB Eco Power LLP has introduced 440 volts, higher and lower voltage cut-off, and a high power factor of up to 0.98.
When asked about the advantage of using the new technology, Poul replies that the company has improved efficiency by up to 95 per cent. “We are working on the development of dimmable driver controls through the mobile app as well as on human-centric light control and management,” says Poul. He adds that the new technology will help save energy, avoid damages from high voltage and current surges, and control lights remotely.
When talking about some of the latest developments in the industry that consumers should be aware of, Sandeep Agarwal, director of iLux Electricals Pvt Ltd, mentions drivers for high wattage luminaires (120W and 165W linear drivers), LEDset interfaces (resistors), SELV drivers and NFC technology.
“Constant improvements in design are always required. While various kinds of protection should be in place to provide a robust design, drivers need to be more reliable and provide better efficiency to save more energy,” says Sundeep Kandoi, director of Quaser Electronics Pvt Ltd. He believes that with the new technologies, manufacturers can improve the reliability and the efficiency of the drivers.
A key factor to remember when making a purchase decision is whether the product is a constant current or a constant voltage type. It is very important to consider the climatic conditions in India. If used locally, the driver must be designed as a universal input, since high voltage fluctuations can cause instrument failure.
Poul suggests that the reliability and quality of the products, the delivery time, the warranty period, the service of the supplier when it comes to replacements, the sharing of knowledge and the technology of the drivers—all play a crucial role in determining the right product before making an investment call. Other factors that people should look for are low voltage and high voltage protection, as well as the isolation and non-isolation techniques used.
Supporting Poul, Kandoi says that the priority for buyers should be reliability and efficiency (power saving), which are the key reasons to opt for LED lighting. “Reliability is important to reduce the maintenance costs, as the manpower costs are always increasing,” Kandoi adds. According to him, buyers should update themselves with all the aspects of the drivers before making a purchase decision. Most end users are not guided properly about the need for high quality LED drivers, and end up buying low quality products based on their low initial cost.
Agarwal adds that a long lifetime of up to 100,000 hours, a low ripple current, ENEC certification, a five-year warranty, and qualified component suppliers are some of the other crucial factors that a buyer should check before making an investment.
A promising future
Market research firm, Reportlinker has reported that the future of the LED driver market looks attractive, with opportunities in the residential, commercial, industrial, and automotive lighting sectors. The global LED driver market is expected to reach an estimated US$ 16.1 billion by 2023 with a CAGR of 15.5 per cent from 2018 to 2023. The major growth drivers for this market are increasing building and construction activities, favourable government regulations to improve energy efficiency, and the increasing adoption of LED lighting in emerging countries.
LED driver manufacturers believe that in the next few years, the field will witness suppliers that adopt a more integrated approach. This will make future LED drivers significantly different from what we see today. Higher levels of efficiency will become the norm, and drivers will also deliver improved performance and power monitoring. In addition, the higher integration of chip systems (SoCs) will continue to reduce the size of the final product while maintaining the overall design reliability.
The Indian government’s decision to replace 35 million streetlights with LED lights by March 2019 under the Street Lighting National Programme (SLNP) is expected to result in high spending on LED drivers in the outdoor lighting industry. Digital signage is another market segment that is creating huge demand for LEDs and the drivers.