Sinusoidal Pulsewidth Modulation Scheme for LED Lighting to Reduce LED Flicker

A sinusoidal pulsewidth modulation (SPWM) dimming scheme for light-emitting diodes (LEDs) is proposed based on the sampling control theory. By driving tricolor LEDs, SPWMs with different block segmentations are compared with the pulsewidth modulation (PWM), whose frequency increases in multiples. The surface temperature, flicker, and harmonic components of the current waveform are investigated for LEDs driven by different current waveforms; the surface temperature of LEDs rises as the duty cycle of the driving current increases. The flicker of tricolor LEDs is analyzed in terms of RC time, and the blue LED is less likely to flicker. The experimental results demonstrate that the SPWM scheme can effectively reduce LED flicker and achieve low electromagnetic radiation interference.