LED lighting design and manufacturing company, Once Innovations, Inc. (ONCE) has introduced initial AC LED lighting products with ONCE proprietary conditioning circuitry that dramatically improves both total harmonic distortion (THD) and power factor (PF) relative to existing AC LED lights.

ONCE believes that its new SCD conditioning circuitry is a key enabling technology for small platform AC LED lighting. SCD conditioning adds a few low cost discrete components to the simple resistive light engine. Products using SCD technology have demonstrated dramatic improvements in efficiency, system luminous efficacy and power quality. In newly introduced AC LED lines with SCD technology, ONCE readily achieved system efficacies above 75 lumens per watt at 2950K and 84 CRI, THD levels under 20%, and PF above 0.98 with the ability of smooth, pseudo-linear dimming from 5-100%. Unlike other existing conditioning technologies, SCD boosts luminous efficacy by about 15% over simple resistive circuits. SCD technology adds no appreciable EMI, thus eliminating the need for filters or shielding.

Zdenko Grajcar, ONCE CTO, compares the emergence of solid-state lighting today with the computer industry several decades ago. "When computers were rapidly proliferating in the '80s and '90s, their non-linear load characteristic had a very low power quality. The large number of low power quality loads on the grid drew the unprecedented attention of utilities and standard setting bodies, and resulted in de facto regulations such as EN61000-3-2. Similarly, poor power quality could impact the viral growth potential of the LED Lighting industry.”

Power quality is already an issue being considered by ENERGY STAR and ENERGY SAVING TRUST. ONCE believes the industry should attain power quality levels of THD under 20% and PF of at least 0.95 for all LED based lamps over 3W. Tests were recently conducted in the ONCE lab regarding the power quality of a number of existing AC LED lights that use either switch mode power supply (SMPS) or simple resistive circuits to condition the current. Regarding those tests, Mr. Grajcar summarized, "It was very troubling to discover that the worst results in power quality were found in products made by some of the largest lighting brands. We have seen some existing SMPS type conditioning circuits that draw a severely distorted current waveform, with THD above 87%. These same SMPS conditioning circuits further degrade power factor by phase shifting the current relative to the sinusoidal line voltage, which usually results in PF around 0.6 or even worse. Power factor correction (PFC) may improve the power quality, but with substantial additional cost and complexity.”

“We do not claim to have developed the most efficient solution,” Mr. Grajcar added, “however, our SCD conditioning technology has proven to be a very robust, compact, and a surprisingly affordable solution – one that may enable AC LED lighting to meet the strict power quality standards at the lowest possible cost. We plan to use the newly developed and patent pending SCD conditioning technology in all ONCE products currently in development, and to offer licensing options to major lighting and LED manufacturers.”