By Candra Marcey, Contributor, BizLED Bureau
June 11, 2015: The electronics part of an LED?the driver?seems to be an indispensable part of it. But it?s no longer so. According to experts, drivers are no longer needed to power an LED light. It can now be powered directly from AC mains. These LEDs are also called driver-free AC LEDs.
AC LED technology makes LEDs work directly by AC100/240v, without any driver. These LEDs can be connected directly to normal power supplies (usually 110V at 60Hz or 230V at 50Hz). The sinusoidal waveform circuit means that at each particular time half the LEDs are off while the other half is on, emitting light. This stage is reversed and repeated continually and, thus produce a constant stream of light.
AC LED light fixtures can also operate directly from the normal power supply and work on voltages from as low as 12V to up to 240V. Common models use a 55V peak for the rising edge or a 110V trailing edge. Many modern AC LED units use a high performance electronic transformer which is capable of a very high intensity signal (typically over 1,000Hz), meaning that flicker is not problem and the light is continuous.
How it works
LED is a diode and its properties can be used to get rid of the electronic circuitry. When two strings of LEDs are connected directly to the mains outlet,and switched in serial, their total forward voltage meets the line voltage. But the added reverse voltages in each single LED must not exceed their added breakdown voltages. For example, if a number of LEDs are placed in a series, the array will become compatible with the mains voltage.
The concept being accepted
Today, many manufacturers favour the idea of driverless LEDs. e:lumix, for instance, developed a LED chip structure with inherent overload protection and LEDs with this semiconductor structure could be used as a building block for driverless AC LEDs.
Driver-free AC LEDs are also cheaper and more reliable than LED-driver combo. They are also dimmable?a common feature in today?s products. When the minimal driver circuit is placed on the circuit board that hosts the LEDs, no separate driver module is needed. In fact, the latest implementations combine up to 93% electrical efficiency with low cost and no perceptible flicker.
Some are against the idea
However, all manufacturers do not like the concept of driverless LED lighting. Also, the driver manufacturers feel threatened by this concept. They believe that this idea will not have good potential. Drivers not only regulate switching power but also provide the correct voltage. It also protects the LEDs against over current, over voltage, transients and voltage peaks.
An AC-LED light engine has many advantages. For example, without an LED driver it becomes a flat and compact design. Flicker is also a common problem, but there are driver-less LED light engine that produces less flicker and offers higher efficiency than many existing products. The new technology results in prototype light engines with essentially no perceptible flicker at 120 Hz and demonstrated electrical efficiency of 93%. This design is being used in a light engine manufactured by ERG Lighting.
It remains to be seen how viable the concept will be in the coming years.
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