A more comprehensive understanding of LED lighting, just these five dimming methods!
Release date: 2018-05-04 Source: Lighting industry information sharing: 
The principle of LED illumination is different from that of traditional illumination. It is based on P-N junction illumination. The same source of LED light source has different current and voltage parameters due to different chips. Therefore, its internal wiring structure and circuit dispersion are different, resulting in The manufacturer's light source has different requirements for dimming drive. Therefore, the mismatch between the control system and the light source and electric appliance has become a common problem in the industry. The diversification of LED also poses a higher challenge to the control system. If the control system and lighting equipment are not matched, it may form a light to extinguish or shine, and may cause damage to the LED drive circuit and light source.
There are five ways to control LED lighting equipment in the mall:
1. Leading edge phase cut (FPC), thyristor dimming
2. Rear edge phase-cut (RPC) MOS tube dimming
3. 1-10V dimming
4. DALI (Digital Addressable Lighting Interface)
5. DMX512 (or DMX) dimming
Front edge phase-cutting control dimming
The leading edge dimming is to select the thyristor circuit. From the beginning of the communication phase 0, the input voltage is chopped until the thyristor is turned on. The principle is to adjust the conduction angle of each half wave of the communication to change the sinusoidal waveform, and then change the effective value of the communication current to complete the dimming intention.
Leading edge dimmers have the advantages of high precision, high efficiency, small size, light weight, and easy remote operation. They are dominant in the market, and most manufacturers' products are this type of dimmer. The leading edge phase control dimmer generally uses a thyristor as a switching device, so it is also called a thyristor dimmer.
The advantages of using FPC dimmers on LED illuminators are: low dimming cost, compatibility with existing lines, and dimming along phase-cutting without rewiring. Downwind is the poor performance of FPC dimming, which generally leads to a reduction in dimming planning, and will result in the minimum required load exceeding the rated power of a single or a few LED lights. Because of the characteristics of the thyristor half-control switch, as long as the function of the current is turned on, and the current cannot be completely turned off, even if the current is adjusted to a minimum, there is still a weak current passing through, and the characteristics of the LED micro-current illuminating make the thyristor dimming many exist. After the shutdown, the LED still has a weak light-emitting phenomenon, which has become a difficult problem in the current wiring-free LED dimming method.
Rear edge phase-cutting control dimming
The trailing edge phase-cutting dimmer is made of a field effect transistor (FET) or an insulated gate bipolar transistor (IGBT) device. The trailing edge phase-cut dimmer generally uses a MOSFET as a switching device, so it is also called a MOSFET dimmer, commonly known as a "MOS tube." The MOSFET is a fully controlled switch that can be operated either on or off, so there is no thyristor dimmer that cannot be completely turned off. Another MOSFET dimming circuit is more suitable for capacitive load dimming than thyristor, but because of the high cost and dimming circuit, it is not easy to make stability and so on, so the MOS tube dimming method has not developed, thyristor Optics still occupy the vast majority of dimming system stores.
Compared to leading-edge phase-cut dimmers, trailing-edge phase-cut dimmers are used in LED lighting because there is no minimum load requirement and then better performance can be achieved in a single lighting device or on a very small load, however, Because MOS tubes are rarely used in dimming systems, they are generally only made into knob-type single-lamp dimmer switches. This low-power post-cut phase dimmer is not suitable for engineering applications. Many lighting manufacturers use this dimmer to do dimming tests on their own dimming drivers and luminaires. Then, the dimming products were pushed to the engineering mall, which led to the situation that the phase-cut dimming driver was modulated by the thyristor dimming system. This mismatch in dimming methods results in dimming, which can quickly damage the power supply or dimmer.
1-10V dimming
The 1-10V dimming device has two independent circuits, one is a common voltage circuit for turning on or off the power to the lighting device, and the other is a low voltage circuit that supplies the reference voltage to tell the lighting device the dimming level. The 0-10V dimming manipulator was previously used in the dimming control of fluorescent lamps. Now, because a constant power supply is added to the LED driver module, and there is a special control circuit, the 0-10V dimmer can support the same. Many LED lights. However, the application of defects is also very obvious, the low-voltage control signal needs to be rated to add a set of lines, which greatly increases the requirements for construction.
DALI dimming
The DALI specification has defined a DALI network that contains a maximum of 64 units (independent addresses), 16 groups and 16 scenes. Different lighting units on the DALI bus can be flexibly grouped to handle and handle different scenarios. In practice, a typical DALI manipulator can control up to 40 to 50 lights, and can divide 16 groups, and can process some actions in parallel. In a DALI network, 30 to 40 manipulation commands can be processed per second. This means that the manipulator handles 2 dimming commands per second for each lighting group. DALI is not a true peer-to-peer network. It is a ballast that operates in place of a 1 to 10V voltage interface. Related to the traditional 1-10V dimming, the advantage of DALI is that each node has only the address code, and with feedback, the far-distance dimming will not appear as the signal attenuation like 1-10V, but this interval in engineering practice It is still not suitable to exceed 200 meters.
Obviously DALI is not suitable for LED lighting control, a DALI network can only control 21-inch full-color LED lamps. DALI is oriented to traditional lighting control, focusing on the system's static control and reliability, stability and compatibility. The planning of the LED lighting system is far greater than the DALI system. It is mainly to seek the expressive power of the lighting art and the intelligentization of the appropriate overall planning system. This requires the system to access a larger bus network, with unlimited expansion capabilities and higher scenarios. Rewrite talent. Therefore, the DALI system is often incorporated into other bus systems as a sub-system in large-scale lighting projects.
The advantages of DALI dimming need not be described, the defects are still annoying signal line placement and high prices. It is worth mentioning that the current DALI dimming driver still needs standby power consumption when turning off the lights in order to ensure that the MCU is on standby at any time.
0DMX512 dimming
The DMX512 protocol was first developed by USITT (American Theatre Skills Association) as a method for manipulating dimmers from a console with a standard digital interface. DMX512 has crossed the imitation system, but it cannot completely replace the imitation system. The simplicity and reliability of the DMX512 (assuming it can be properly installed and used) and its flexibility make it an option for funding.
In practice, the DMX512's control method generally plans the power supply and the controller together. The DMX512 controller controls 8 to 24 lines and directly drives the RBG line of the LED lamps. However, in the construction of the lighting project, because the DC line is weak, it is required to install a controller at about 12 meters, and the control bus is a parallel method. Therefore, the manipulator has a lot of wiring, and many occasions can not be constructed. The DMX512 receiver needs to set the address so that it can receive the dimming command clearly, which is also very inconvenient in practice. Multiple manipulators are interconnected to handle cluttered lighting schemes, and operational software planning can be messy. Therefore, DMX512 is more suitable for occasions where lamps are gathered together, such as stage lights.
In summary, the primary drawback of DMX manipulators is the need for special wiring layouts and types, and the need for proper programming to set the underlying color and scene, which is more costly for later protection.
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