Small knowledge sharing of SCR dimming power source for LED

- May 25, 2017-

LED dimming power supply with the continuous development of technology, there are many kinds of technology can be realized, the most common and one is the SCR dimming. The derivative of the LED dimming power source is also a lot of, below we only introduce the SCR tunable photoelectric sources.

Before we know the LED dimming power supply, we first know what is the SCR dimming? Here is a little personal summary of some of the small knowledge, to share. SCR is also called thyristor, consisting of four layers, a total of three pn knots.

The working principle of SCR dimming is to generate a tangential output voltage waveform after the waveform of the input voltage is "through the conduction angle. By applying the tangential principle, the effective value of the output voltage can be reduced to reduce the power of the ordinary load (resistive load). The advantages of controllable silicon dimming are high efficiency and stable performance. However, with the rise of LED lamps and lanterns, there is a compatibility problem between TRIAC dimming and led.

Not all phase controllers are cut off in the same direction as the AC sine wave. The three-terminal bidirectional controllable silicon device is used for incandescent lamp and halogen light dimming, which is cut off from the front phase of the sine wave, at the cut-off point, the input voltage is just over 0 and the input current is just reversed. Therefore, it is also called the cutting-phase control dimmer, which is the front-end SCR dimmer, and the front-phase control dimmer produces an electric current spike at the beginning of the conduction, which causes the beep and increases the pressure of the electronic drive.

The inverse-phase control dimmer (i.e., the rear-tangent dimmer) is also said to be able to avoid the above problems after the SCR dimming, because it is from the second half of the AC sine wave or the back of the start off the dimmer. The inverter-controlled dimmer is conductive when the input current has just changed direction, allowing the voltage to gradually rise and then cutting it in the next half of the cycle. The inverse-phase control dimmer is also called the Electronic Low-voltage (ELV) dimmer, which is used to improve the performance of halogen lamps using electronic transformers.

Therefore, in theory, the SCR dimming power supply is more suitable for led dimming.

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