Warm and new knowledge: five kinds of dimming methods for LED lighting

Intelligent lighting has occupied an important position in the smart home industry due to its market advantages such as high efficiency, energy saving, simple management and diversified control. However, the technical problem that smart lighting is difficult to solve at present is LED dimming. What is the current dimming mode of LED lighting equipment?

There are five LED lighting control methods on the market:

Front 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-cut control dimming

principle:

The leading edge dimming is to use a thyristor circuit. Starting from the AC phase 0, the input voltage is chopped until the thyristor is turned on. That is to say, the leading edge is turned on, and the light is dimmed by means of a natural zero-off.

LED fluorescent lamp power front dimmer has the advantages of high adjustment precision, high efficiency, small size, light weight and easy remote control. It is dominant in the market, and most manufacturers' products are this type of dimmer. However, the front cut dimmer is prone to loud noise, and this dimming method is not recommended when the requirements are high.

Rear edge phase-cut control dimming

principle:

LED fluorescent lamp power supply rear edge dimming uses a triode circuit, the dimmer chopping the input voltage waveform. Turn off from one phase and turn on at 180 degrees.

LED fluorescent lamp power supply trailing edge dimming: MOS/IGBT technology with zero-crossing and trailing edge turn-off solves the problem of grid interference and noise.

Compared with the front-end phase-cut control dimming mode, the backward edge tangential control dimming has better compatibility, but the internal circuit structure is more complicated and the control cost is relatively high.

1-10V dimming

principle:

The principle of 1-10V dimming mode can correspond to the following figure. The relationship between the abscissa control voltage and the right ordinate luminous flux is: when the control voltage is 1V, the luminous flux is at least 1%, and when the control voltage is 10V, the luminous flux is 100% max. In this dimming process, the two are linear.

For example: there are a lot of lights in a room, we have a set of 1-10V control lines less than 50 meters for each lamp, and connected to the controller. When the controller is adjusted, the voltage on the control line changes and the lamp is dimmed or dimmed.

The disadvantage of 1-10V dimming is that multiple sets of luminaires on a control panel can only change at the same time. If you want to achieve different control of each lamp, you can only make the control panel and the luminaires correspond one by one. When you get more, it will obviously become very troublesome to operate.

DALI dimming

When multiple lamps need to be dimmed, DALI dimming can be used instead of 1-10V dimming. DALI dimming is a typical digital control method.

principle:

DALI (Digital Addressable Lighting Interface) is an internationally-recognized lighting control communication protocol with a communication speed of 1200 BPS ± 10%. Mainly used for dimming control of multiple fluorescent lamps and LED lighting. DALI can form a network with a maximum of 64 short addresses and 16 group addresses. A host can control one or more slaves to communicate in half-duplex mode.

DALI has four letters each with meaning: Digital number, Addressable addressable, Lighting, Interface interface.

DALI can dim each luminaire with DALI drive, and different lighting units on the DALI bus can be flexibly grouped for different scene control and management. Compared with other dimming methods, the advantages of DALI dimming are:

1. Digital dimming, precise and stable dimming;

2, DALI can communicate in two directions, can feedback the situation of the lamp to the system;

3. DALI control is more flexible;

4, DALI anti-interference ability.

DMX512 dimming

The DMX512 protocol was first developed by USITT (American Theatre Technology Association) as a way to use the standard digital interface from the console to control the dimmer. The DMX512 goes beyond analog systems but does not completely replace analog systems. The simplicity, reliability (if properly installed and used) and flexibility of the DMX512 make it an option for funding.

principle:

The DMX512 is controlled by a combination of power and controller. The DMX512 controller controls the 8 to 24 lines and directly drives the RBG lines of the LED lamps.

In the architectural lighting project, because the DC line is weak, it is required to install a controller at about 12 meters, and the control bus is in parallel mode. Therefore, the controller has a lot of wiring, and even in many occasions, it is impossible to construct. The receiver of the DMX512 needs to set the address so that it can explicitly receive the dimming command, which is also very inconvenient in practical applications. Multiple controllers are interconnected to control complex lighting solutions, and operating software design can be complex. Therefore, DMX512 is more suitable for occasions where lamps are concentrated, such as stage lighting.

The main disadvantage of DMX controllers is the need for special wiring layouts and types, and the need for programming to set basic colors and scenes, which is costly for later maintenance.

DMX512 features:

Each output loop supports a maximum of 512 channels;

Each output loop supports a maximum of 512 channels. Depending on the number of channels occupied by the device, the maximum number of devices that can be carried per port is determined.