Active Power Control of Retrofit LED Tube Lamps for Achieving Entitled Energy Savings in View of the EU Ban on Mercury

The performance of commercially available retrofit LED tubes intended for the replacement of linear fluorescent lamps is measured and analyzed with respect to "real-world" installed electronic ballasts, as ascertained through field recovery from installed bases, such as office buildings, parking garages, and industrial installations in western Europe from 2018 to 2020. Results show a wide variation in lamp power draw, which not only thwarts the energy-saving and climate protection aspects of the LED retrofit solution but also poses potential safety risks. Given the EU's goals under the Restriction of Hazardous Substances (RoHS) directive to phase out mercury-containing fluorescent lighting, starting from September 2023, the situation is alarming. We show that this lamp power spread is due to the fundamental differences in impedance between fluorescent lamps and LEDs, in combination with the passive nature of the driver electronics that are currently employed in commercially available LED tube lamps. In response to this disparity, a novel driver topology including active power control (APC) is introduced, which shows that the power-spread problem can be avoided, and we offer a manufacturable solution. A prototype retrofit LED tube lamp incorporating this APC driver technology is shown to deliver safe and predictable energy savings, outlining a path toward guaranteeing the expected return-on-investment and positive environmental impact of the solid-state lighting replacement of mercury-containing linear fluorescent lamps.