The most common dimming control for medium power LED systems is triac dimming, which
constitutes the major problem of input current waveform being significantly distorted due to
chopping and the resulting system having high total harmonic distortion (THD) values along
with low driver efficiencies. The Electromagnetic Compatibility standard EN 61000-3-2-2014
defines THD limits for lighting equipment above 25 W. However, the standard does not specify
a limit for systems below 25 W, making triac dimmers appealing for dimming low power LED
systems even though the resulting THD, efficiency and power factor values are unsatisfactory.
This study aims at evaluating the dimming properties of a flyback LED driver below 25 W,
therefore not limited by the EMC standard. For this aim, dimming is separately performed
through triac dimming, primary side DC link control with and without power factor correction and
the results are analysed.