Five ways to dim LED lighting
Five ways to dim LED lighting
Nowadays, most LED lighting problems are caused by the mismatch between the control system and the light source appliances, which has become a common problem in the industry. At the same time, the diversification of LED lamps and lanterns also put forward a higher challenge to the control system. The LED light-emitting principle is different from traditional lighting. It is by P-N junction light, and the same power LED light source; the current and voltage parameters are different because of the other chips used. Hence, its internal wiring structure and circuit distribution are also different, resulting in the light source of the manufacturers of dimming drive requirements are not the same. If the control system and lighting equipment do not match, it may cause the lights to go out or flicker and may cause damage to the LED lighting driver circuit and light source.
There are five types of LED lighting equipment control methods on the market.
1, leading-edge phase cutting (FPC), silicon controlled dimming
2, trailing edge phase cutting (RPC) MOS tube dimming
3, 1-10VDC
4, DALI (digital addressable lighting interface)
5, DMX512 (or DMX)
1, cutting-edge phase control dimming
Frontier dimming uses a silicon-controlled circuit, starting from the AC phase 0, the input voltage chopper until the silicon controlled conductive voltage input.
The principle is to adjust the conduction angle of each half-wave of AC power to change the sinusoidal waveform, thereby changing the RMS value of AC to achieve the purpose of dimming.
Frontier dimmers have the advantages of high regulation accuracy, high efficiency, small size, lightweight, easy to manipulate over long distances, etc., dominate the market. Most manufacturers of products are this type of dimmer.
Frontier phase control dimmers generally use silicon-controlled as a switching device, so also known as silicon-controlled dimmers on LED lighting using FPC dimmers have the advantage of the low cost of dimming, compatible with existing wiring, no rewiring. The disadvantage is that FPC dimming performance is poor, usually resulting in a reduced dimming range, and can lead to the minimum required load is more than a single or a small number of LED lighting power ratings.
Because of the properties of silicon controlled semi-controlled switch, only the function of turning on the current, but not entirely off the present, even if adjusted to the lowest, still have a weak current through, and LED micro-current light characteristics, so that a large number of dimming with silicon controlled LED off there is still a weak light phenomenon, which has become the current problem of the promotion of this wiring-free LED dimming method.
E-Linker professional research and development of cutting-edge phase LED dimming driver is an excellent solution to this problem, through the drive circuit "C-TURNOFF" technology optimization to avoid "off constantly" and " strobe bad light" and other issues.
Matching E-Linker easy to link before cutting phase LED dimming driver of various types of lamps and lanterns can be perfectly matched with other silicon dimming systems, saving the user wire and wiring hours, solving the silicon LED dimming matching and not of the confusing pattern.
2, the back edge of the phase-cut control dimming
Back edge phase control dimmer uses field-effect transistor (FET) or insulated gate bipolar transistor (IGBT) equipment. Rear-edge tangential dimmers generally use MOSFET as a switching device, also known as MOSFET dimmers, commonly known as "MOS tube.
MOSFET is a complete control switch; both controls can also be controlled off, so no silicon dimmers can not completely shut down the phenomenon.
Another MOSFET dimming circuit is more suitable for capacitive load dimming than silicon, but because of the high cost and dimming circuit is relatively complex, not easy to do stability and other characteristics, making the MOS dimming method did not develop, silicon dimmers still occupy the majority of the dimming system market.
Compared with the front cut phase dimmer, after the edge of the cut phase, dimmer is applied to LED lighting equipment because there are no minimum load requirements so that you can achieve better performance on a single lighting device or a minimal load, but because MOS tubes are rarely used in dimming systems, generally only made into a knob-type single light dimmer switch, this tiny power after the cut phase dimmer does not apply to the engineering field.
And many lighting manufacturers apply this dimmer to their dimming drivers and lamps to do dimming tests. Then their dimming products to the engineering market, resulting in engineering often appear with silicon dimming system modulation after the cut phase dimming driver.
This dimming mismatch leads to dimming flicker; serious will quickly damage the power supply or dimmer.
3, 1-10V dimming
1-10V dimming device within two separate circuits, one for the ordinary voltage circuit, used to turn on or off to the power supply of the lighting equipment, the other is a low-voltage circuit, which provides a reference voltage to tell the lighting equipment dimming level, 0-10V dimming controller previously commonly used in the dimming control of fluorescent lamps, now, because the LED driver module with a constant power supply, and a unique control line, so 0-10V dimmers can also support a large number of LED lighting.
But the application of disadvantages is also self-explanatory; a low voltage control signal requires an additional set of lines, which significantly increases the requirements for construction.
4, DALI dimming
DALI standard has defined a DALI network, including a maximum of 64 units (can be independently addressed), 16 groups, and 16 scenes. Different lighting units on the DALI bus can be flexibly grouped to achieve other scenes control and management.
In practical applications, a typical DALI controller controls up to 40-50 lights, divided into 16 groups while simultaneously handling several actions. In a DALI network, 30 to 40 control commands can be processed per second. This means that the controller needs to manage two dimming orders per second for each lighting group.
DALI is not really a point-to-point network; it is instead of 1-10V voltage interface control ballast. Compared to the traditional 1-10V dimming, DALI's advantage is that each node has a unique address code. With feedback, more distance dimming will not be as 1-10V signal attenuation, but the engineering practice of this distance or should not exceed 200 meters.
DALI is not suitable for LED lighting control; a DALI network can only control 21 full-color LED lamps and lanterns. DALI is oriented to traditional lighting control, focusing on the static control of the system and reliability, stability, compatibility.
The scale of the LED lighting system is much larger than the DALI system, which mainly pursues the expressiveness of the artistic effect of the lamps and lanterns and takes into account the intelligence of the system appropriately, which requires the system to access a more extensive bus network with unlimited scalability and higher scene refresh capability.
Therefore, the DALI system in large lighting projects is often incorporated into other bus systems as a subsystem. e-Linker COS system can be perfectly compatible with the DALI system. the advantages of DALI dimming need not be repeated. The disadvantage is still annoying signal line arrangement and high prices.
It is worth mentioning that the current DALI dimming driver, to ensure that the microcontroller is always on standby when the lights are turned off, still needs to standby power consumption. Equipped with E-Linker dimmers can be physically powered off when the lights are turned off to avoid energy loss on standby.
5, DMX512 dimming
DMX512 protocol was first developed by USITT (United States Theatre Technology Association) to become a standard digital interface from the console to control the dimmer.
DMX512 is beyond the analog system but can not wholly replace the analog system. dMX512 simplicity, reliability (if it can be installed and used correctly), and flexibility to make it a protocol of choice when funds are available.
In practice, the DMX512 control method, generally the power supply and controller are designed together.
Controlled by DMX512 controller 8 to 24 lines, direct-drive LED lamps RBG line. Still, in the building lighting project, due to the DC line weakening significantly, it requires about 12 meters to install a controller, control bus for parallel mode; therefore, the controller alignment is very much, many occasions even can not be constructed.
DMX512 receiver needs to set the address to receive dimming instructions, which is also very inconvenient in practice. Multiple controller interconnections to control complex lighting schemes, the functional software design will also be more complicated.
This analysis shows that DMX512 is more suitable for lamps and lanterns together, such as stage lighting. In summary, the main drawback of the DMX controller is the need for a particular wiring layout and type. It requires a certain amount of programming to set the primary colors and scenes, which is more costly for later maintenance.
