Disadvantages of using TRIAC dimming in LED lighting

It is not a good choice to dim LED lighting fixtures using TRIAC dimmers. The reason why semiconductor suppliers generally launch LED drivers that support TRIAC dimming is not because this dimming method has any particularly excellent performance, but because consumers want convenience. Because many European and American home markets today generally use TRIAC dimmers to dim incandescent lamps, they hope to use LED lamps to directly replace incandescent bulbs without any modification to the existing infrastructure, that is, without any rewiring work.

The problem is that TRIAC dimmers have five adverse effects on LED lighting fixtures with capacitive loads, so strictly speaking this is not a good dimming technology.

The first major adverse effect is that TRIAC dimming will inevitably destroy the power factor because it uses a chopping wave method for dimming. Especially when deep dimming is used, the power factor will become very low, which will in turn affect the quality of the entire power grid.

The second major adverse effect is that TRIAC dimming will produce serious EMI interference. This is because when the load is capacitive, the turn-on and turn-off of the thyristor will produce a strong surge in the output current waveform, and this surge current will cause serious EMI interference.

The third major adverse effect is that TRIAC dimming will cause low power conversion efficiency of the entire lamp. When deep dimming is performed, the efficiency will be less than 20%.

The fourth major adverse impact is that TRIAC dimmers are not compatible with LED lighting fixtures, which can easily cause output light flickering, affecting consumer experience and even causing health problems.

The fifth adverse impact is that TRIAC dimmers can cause serious THD problems, and international energy standards such as EN61000-3-2 are beginning to require strict THD specifications.

In short, it is not a good choice to use TRIAC dimmers for dimming LED lighting fixtures. Dr. Liu Guanghua, general manager of Taiwan New Green Technology, pointed out: "Strictly speaking, TRIAC dimmers are a low-quality product that is increasingly difficult to correct for energy conservation and environmental protection, power systems and general consumers. It is recommended that everyone use other intelligent dimming technologies."