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Five dimming methods for LED lighting

- Sep 21, 2018-

Today's LED lighting problems are mostly caused by the mismatch between the control system and light source appliances, which has become a common fault in the industry, and LED diversification also poses a higher challenge to the control system。 Because the principle of LED is different from the traditional lighting, it relies on P-N junction。 The same power LED light source uses different chips and different current and voltage parameters, so its internal wiring structure and circuit distribution are different, resulting in different manufacturers'requirements for dimming driver。 If the control system and lighting equipment do not match, it may cause the lights to go out or flicker, and may damage the LED drive circuit and light source。

 

There are five LED lighting control modes on the market: _

1, front tangent (FPC), silicon controlled dimming_

2, rear tangent (RPC) MOS tube dimming_

3, 1-10 VDC_X

4, DALI (digital addressable lighting interface)

5, DMX512 (or DMX)

  

1. Front-end phase-controlled dimming
Front-end phase-controlled dimming is the use of SCR circuit, starting from AC phase 0, input voltage chopper, until the SCR turn on, voltage input. It
Its principle is to adjust the conduction angle of each half wave of alternating current to change the sinusoidal waveform, thereby changing the effective value of alternating current, so as to achieve the purpose of dimming. It
_front dimmer has the advantages of high adjusting precision, high efficiency, small volume, light weight, easy long-distance control and so on. It occupies the leading position in the market. Most manufacturers'products are this type of dimmer.
Apparatus。

 

Front-end phase-controlled dimmers generally use silicon-controlled as switching devices, so they are also called silicon-controlled dimmers in LED lighting using FPC dimmers have the advantages of low dimming costs, compatibility with existing lines, without rewiring. The disadvantage is that FPC dimming performance is poor, usually resulting in a narrow dimming range, and will lead to a minimum load exceeding a single or a small number of LED lighting rated power.

 

Because of the properties of SCR semi-controlled switch, only the function of switching on the current can not turn off the current completely, even at the lowest level there is still a weak current passing through, and the characteristics of LED micro-current luminescence, making a large number of SCR dimming LED still has a weak luminous phenomenon after turning off, become the current wiring-free LED tuning. The difficulty of light propagation. It

E-Linker Professional research and development of cutting-edge LED dimming driver to solve this problem very well, through the drive circuit of the "C-TURNOFF" technology to optimize the avoidance of "off" and "flashing bad lights" and other problems。

All kinds of lamps and lanterns matched with E-Linker easy-to-connect pre-tangent LED dimming drive can be perfectly matched with other SCR dimming systems, saving wire and wiring time for users, and resolving the confusion of SCR LED dimming matching and non-turning off。

 

2。 Rear-end phase-controlled dimming


Rear-end
phase-controlled dimming is made of field effect transistor (FET) or insulated gate bipolar transistor (IGBT) equipment. Back-edge tangent dimmer generally uses MOSFET as a switch device, so it is also called MOSFET dimmer, commonly known as "MOSFET". It
MOSFET is a fully controlled switch, which can be controlled on or off, so there is no phenomenon that the SCR dimmer can not be completely turned off. It
In addition, MOSFET dimming circuit is more suitable for capacitive load dimming than thyristor dimming circuit, but because of the high cost and relatively complex dimming circuit, it is not easy to do stable characteristics, so that MOSFET dimming mode has not developed, thyristor dimmer still occupies most of the dimming system market. Compared with the front tangent dimmer, the rear tangent dimmer can achieve better performance in a single illumination device or a very small load because it has no minimum load requirement. However, since MOS transistors are seldom used in dimming systems, they are generally made into knob-like single-lamp dimmers. Switch, this small power post phase dimmer is not suitable for engineering.est. Then put their own dimming products into the engineering market, resulting in the project often appear in the use of silicon controlled dimming system modulation after the tangent dimming drive. It
The mismatch of this dimming method causes dimming flicker, which can seriously damage the power supply or dimmer quickly.

 

3. 1-10V dimming


1-10V dimming device has two independent circuits, one is a common voltage circuit, used to turn on or off the power supply to lighting equipment, the other is a low voltage circuit, which provides a reference voltage, telling lighting equipment dimming level, 0-10V dimming controller used to dimming control of fluorescent lamps, now, because A constant power supply is added to the LED drive module and a special control circuit is provided, so the 0-10V dimmer can also support a large number of LED lights. It
However, the application shortcomings are also very obvious, low voltage control signals need to add an additional set of lines, which greatly improves the construction requirements.

 

4, DALI
The DALI standard has defined a DALI network that includes the largest 64 units (independent addresses), 16 groups, and 16 scenarios. Different lighting units on DALI bus can be flexibly grouped to realize different scene control and management. It
In practical applications, a typical DALI controller controls up to 40 to 50 lights, which can be divided into 16 groups and can handle some actions in parallel. In a DALI network, 30~40 control instructions can be processed per second. This means that the controller needs to manage 2 dimming instructions for each lighting group per second. It
DALI is not a real point to point network. It controls the ballast in place of the 1 ~ 10V voltage interface. Compared with the traditional 1-10V dimming, DALI has the advantage that each node has a unique address code, and with feedback, more remote dimming does not appear as 1-10V signal attenuation, but in engineering practice this distance should not exceed 200 meters.

Obviously, DALI is not suitable for LED lighting control, and a DALI network can only control 21.
Color LED lamps and lanterns. DALI is oriented to the traditional lighting control, focusing on the static control of the system and reliability, stability, compatibility. It
The scale of LED lighting system is much larger than that of DALI system. It mainly pursues the artistic effect of lamps and lanterns and takes into account the intelligence of the system properly. This requires the system to connect to a larger bus network, with unlimited expansion ability and high scene refreshing ability.

Therefore, the DALI system is often incorporated into other bus systems as a subsystem in large lighting projects. E-Linker's COS system can be perfectly compatible with the DALI system. The advantages of DALI dimming do not need to be repeated. The disadvantages are still annoying signal line layout and high price. It is worth mentioning that the current DALI dimming drive in order to ensure that the microcontroller is always on standby, it still needs to be standby power consumption when the light is off. The dimmer equipped with E-Linker is able to turn off the lights when the light is turned off, and avoid energy loss during standby.

5, DMX512 dimming


The DMX512 protocol was first developed by USITT (the American theater Technology Association) from the console.
Use standard digital interface to control dimmer. It
DMX512 is beyond the analog system, but it can not completely replace the analog system. The simplicity, reliability (if properly installed and used) and flexibility of DMX512 make it a choice of protocol when funding allows.

 

In practical applications, the control mode of DMX512 usually involves the design of power supply and controller. It
DMX512 controller controls 8-24 lines and directly drives the RBG line of LED lamps. But in the building lighting project, because of the weakness of the DC line, a controller is required to be installed about 12 meters. The control bus is in parallel mode. Therefore, the controller can not even be constructed in many occasions. It
The DMX512 receiver needs to set an address so that it can receive the dimming instructions clearly, which is very inconvenient in practical applications. Multiple controllers interconnect to control complex lighting schemes, and the design of operation software will be more complicated.

From this analysis, we can see that DMX512 is more suitable for occasions where lamps are concentrated together, such as stage lighting. In summary, the main drawbacks of the DMX controller described above are that it requires a special wiring layout and type, and a certain amount of programming to set the basic colors and scenes, which is for later maintenance.
The cost is greater.

 

 


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