The five dimming control methods of LED high bay light are explained in detail. The light-emitting principle of LED is different from traditional lighting. It relies on P-N junction to emit light. The LED high bay light source of the same power has different current and voltage parameters because of the different chips used, so its internal wiring The structure and circuit distribution are also different, resulting in different requirements for the dimming drive of the light sources of various manufacturers. Therefore, the mismatch between the control system and the light source electrical appliances has become a common problem in the industry. At the same time, the diversification of LED high bay lights Control systems also present higher challenges. If the control system and lighting equipment are not matched, it may cause the light to go out or flicker, and may cause damage to the drive circuit and light source of the LED high bay light. There are five LED high bay lighting control methods on the market:
1. Frontier Phase Cut (FPC), SCR dimming
2. Rear edge phase cut (RPC) MOS tube dimming
3. 1-10VDC
4. DALI (Digital Addressable Lighting Interface)
5. DMX512 (or DMX)
1. Frontier phase-cut control dimming
Leading edge dimming is to use thyristor circuit, starting from AC phase 0, the input voltage is chopped, and there is no voltage input until the thyristor is turned on. The principle is to adjust the conduction angle of each half-wave of the alternating current to change the sine waveform, thereby changing the effective value of the alternating current, so as to achieve the purpose of dimming.
Leading-edge dimmers have the advantages of high adjustment accuracy, high efficiency, small size, light weight, and easy long-distance manipulation. They are dominant in the market, and most manufacturers' products are this type of dimmer. The leading edge phase control dimmer generally uses thyristor as the switching device, so it is also called thyristor dimmer.
The advantages of using FPC dimmers on LED high bay lighting are: low dimming cost, compatibility with existing wiring, and no need for rewiring. The disadvantage is that the dimming performance of FPC is poor, which usually leads to a reduction in the dimming range, and will cause the lowest required load to exceed the rated power of a single or a small number of LED high bay lights. Because of the properties of the thyristor half-controlled switch, it only has the function of turning on the current, but cannot completely turn off the current. Even if it is adjusted to the lowest level, there is still a weak current passing through. After a large amount of light exists, the LED high bay light still emits weak light after it is turned off, which has become a difficult problem in the promotion of this wiring-free LED high bay light dimming method. The cutting-edge phase-cut LED high bay light dimming driver developed by E-Linker has solved this problem very well. The "C-TURN OFF" technology of the drive circuit is optimized to avoid "continuous off" and "flickering bad lights", etc. problem. All kinds of lamps and lanterns that match the dimming drive of E-Linker front-cut LED high bay light can be perfectly matched with other thyristor dimming systems, saving the wire and wiring man-hours for users, and solving the dimming of thyristor LED high bay lights. Matching and unstoppable chaos.
2. PWM 2. Trailing edge phase-cut control dimming
The trailing edge phase-cut control dimmer is made of field effect transistor (FET) or insulated gate bipolar transistor (IGBT) devices. The trailing edge phase-cut dimmer generally uses MOSFET as the switching device, so it is also called MOSFET dimmer, commonly known as "MOS tube". MOSFET is a fully controlled switch, which can be controlled both on and off, so there is no phenomenon that the thyristor dimmer cannot be completely turned off. In addition, the MOSFET dimming circuit is more suitable for capacitive load dimming than the thyristor, but because of the high cost and the relatively complex dimming circuit, which is not easy to be stabilized, the MOSFET dimming method has not been developed, and the thyristor dimming method has not been developed. Optical devices still occupy the vast majority of the dimming system market.
Compared with the leading edge phase-cut dimmer, the trailing edge phase-cut dimmer is applied to LED high bay lighting equipment, because there is no minimum load requirement, it can achieve better performance on a single lighting equipment or very small load However, since MOS tubes are rarely used in dimming systems, they are generally only made into knob-type single-lamp dimming switches. This low-power post-cut dimmer is not suitable for engineering. And many lighting manufacturers use this dimmer to do dimming tests on their own dimming drivers and lamps. And then push their own dimming products to the engineering market, which often leads to the situation of phase-cut dimming driving after modulation with thyristor dimming system in engineering. This mismatch of dimming methods leads to dimming flickering, which can quickly damage the power supply or dimmer.
3. 1-10V dimming
There are two independent circuits in the 1-10V dimming device, one is a common voltage circuit, which is used to turn on or off the power supply to the lighting equipment, and the other is a low-voltage circuit, which provides a reference voltage and tells the lighting equipment the dimming level , 0-10V dimming controller was commonly used in the dimming control of fluorescent lamps. Now, because a constant power supply is added to the LED high bay light drive module and there is a special control circuit, the 0-10V dimmer is also Can support a large number of LED high bay lighting. However, the application disadvantages are also very obvious. The low-voltage control signal requires an additional set of lines, which greatly improves the construction requirements.
4. DALI
The DALI standard has defined a DALI network, including the largest 64 units (which can be independently addressed), 16 groups and 16 scenes. Different lighting units on the DALI bus can be flexibly grouped to achieve different scene control and management. In practical applications, a typical DALI controller controls up to 40 to 50 lamps, which can be divided into 16 groups, and can process some actions in parallel. In a DALI network, 30 to 40 control commands can be processed per second. This means that the controller needs to manage 2 dimming commands per second for each lighting group. DALI is not a real point-to-point network, it is a control ballast instead of a 1~10V voltage interface. Compared with the traditional 1-10V dimming, the advantage of DALI is that each node has a unique address code and has feedback. The longer-distance dimming will not experience signal attenuation like 1-10V, but in engineering practice, this distance is still Should not exceed 200 meters.
Obviously DALI is not suitable for LED high bay lighting control, a DALI network can only control 21 full-color LED high bay lamps. DALI is for traditional lighting control, focusing on the static control and reliability, stability and compatibility of the system. The scale of the LED high bay lighting system is much larger than that of the DALI system. It mainly pursues the artistic effect of lamps and lanterns, and properly takes into account the intelligence of the system. This requires the system to be connected to a larger bus network, with unlimited expansion capabilities and high The scene refresh ability. Therefore, DALI systems are often incorporated into other bus systems as a subsystem in large lighting projects. The COS system of the E-Linker is perfectly compatible with the DALI system.
The advantages of DALI dimming need not be repeated, the disadvantages are still annoying signal wiring layout and high price. It is worth mentioning that the current DALI dimming driver still needs standby power consumption when the light is turned off in order to ensure that the microcontroller is in a standby state at any time. Dimmers equipped with E-Linker can physically power off when lights are turned off, avoiding energy loss during standby.
5. DMX512 dimming
The DMX512 protocol Z was first developed by the USITT (American Society of Theatre Technology) as a standard digital interface for consoles to control dimmers. DMX512 surpasses the analog system, but cannot completely replace the analog system. The simplicity, reliability (if properly installed and used) and flexibility of the DMX512 make it the protocol of choice when money allows. In practical applications, the control method of DMX512 is generally to design the power supply and the controller together. The DMX512 controller controls the 8-24 lines, and directly drives the RBG line of the LED high bay light fixture. However, in the building lighting project, due to the large weakening of the DC line, it is required to install a controller about 12 meters. The control bus is Parallel mode, therefore, the wiring of the controller is very large, and it is even impossible to construct in many occasions. The receiver of DMX512 needs to set the address so that it can receive the dimming command explicitly, which is also very inconvenient in practical application. Multiple controllers are interconnected to control complex lighting schemes, and the design of operating software will also be more complex. Therefore, DMX512 is more suitable for occasions where lamps are concentrated together, such as stage lighting. To sum up, the main disadvantage of DMX controller is that it requires special wiring layout and type, and requires certain programming to set basic colors and scenes, which is costly for later maintenance.
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