Better Efficiency with Linear-Regulator compared to Flyback-Converters in LED Lamps at AC Grids
Conference: PCIM Asia 2015 - International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management
06/24/2015 - 06/26/2015 at Shanghai, China
Proceedings: PCIM Asia 2015
Pages: 5Language: englishTyp: PDF
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Authors:
Jaschke, R.; Hoffmann, K. F. (Helmut Schmidt University / University of the Federal Armed Forces Hamburg, Faculty of Electrical Engineering, Power Electronics, Holstenhofweg 85, 22043 Hamburg, Germany)
Abstract:
LED lamps replace conventional lighting sources because of longer operating life, no mercury problems and genial luminous efficacy. Conventional LED power supplies at AC grid have a constant LED current regulation with a switched Flyback converter powered of a DC link capacitor, B2-bridge and line filter. Here we take a simple topology with a linear regulator transistor [1] with DC capacitor, B2-bridge without filter. Our LED lamp consists of filament LEDs (100 series LEDs) with a high LED voltage who is a little bit under the minimal capacitor voltage. We show the circuit dimensioning for ?10% grid voltage variation and LED-voltage changing with measured negative voltage temperature coefficients. With measurements and simulations we get efficiencies of 85% to 96%. With a 4 Watt filament LED lamp at the 230V/50Hz grid we have the best efficiency 91% (20deg C) and 96% (-20deg C) with a 108 LED filament lamp and a bigger DC-capacitor. The luminous efficacy goes from 120 Lumen/Watt to 130 Lumen/Watt, that is certificated in the European Area with the Index A++.