Reliability Prediction of Integrated LED Lamps with Electrolytic Capacitor-Less LED Drivers

AC-DC LED drivers may have a lifespan shorter than the lifespan of LED chips if electrolytic capacitors are used in their construction. Using film capacitors solves this problem but, as their capacitance is considerably lower, the low-frequency ripple will increase. Solving this problem by limiting the output ripple to safe values is possible by distorting the input current using harmonic injection technique, as long as these harmonics still complies with Power Factor Regulations (Energy Star). This harmonic injection alleviates the requirements imposed to the output capacitor in order to limit the low-frequency ripple in the output. This idea is based on the fact that LEDs can be driven by pulsating current with a limited Peak-To-Average Ratio (PTAR) without affecting their performance. By considering the accurate model of LEDs, instead of the typical equivalent resistance, this paper presents an improved and more reliable calculation of the intended harmonic injection. Wherein, its orders and values can be determined for each input/output voltage to obtain the specified PTAR and Power Factor (PF). Also, this harmonic injection can be simply implemented using a single feedback loop, its control circuit has features of wide bandwidth, simple, single-loop and lower cost. A 21W AC-DC buck converter is built to validate the proposed circuit and the derived mathematical model and it complies with IEC61000 3-2 class D standard.

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High-Efficiency Asymmetrical Half-Bridge Converter Without Electrolytic Capacitor for Low-Output-Voltage AC–DC LED Drivers

IEEE Transactions on Power Electronics ◽

10.1109/tpel.2012.2213613 ◽

2013 ◽

Vol 28 (5) ◽

pp. 2539-2550 ◽

Cited By ~ 76

Author(s):

M. Arias ◽

Marcos Fernández Diaz ◽

D. G. Lamar ◽

D. Balocco ◽

Almadidi Aguissa Diallo ◽

...

Keyword(s):

Output Voltage ◽

High Efficiency ◽

Electrolytic Capacitor ◽

Led Drivers

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A Novel Synchronous Current-Doubler Rectifier for LED Drivers Without Electrolytic Capacitors

Journal of Circuits System and Computers ◽

10.1142/s0218126619501755 ◽

2019 ◽

Vol 28 (10) ◽

pp. 1950175

Author(s):

Jianguang Ma ◽

Xueye Wei ◽

Liang Hu ◽

Junhong Zhang

Keyword(s):

High Efficiency ◽

Light Emitting Diode ◽

Low Cost ◽

Electrolytic Capacitor ◽

Storage Capacitor ◽

Led Driver ◽

Large Space ◽

Light Emitting ◽

Short Lifespan ◽

Led Drivers

High-brightness light-emitting diode (LED) lamps have attracted much attention because of their high efficiency, simple structure, energy conservation and environmental protection aspects, and long lifetime. Thus, an LED driver must have a long lifespan, high density, and compact space. However, conventional LED power supplies use an electrolytic capacitor as the storage capacitor in the holdup time, which has a short lifespan and occupies large space. In this paper, a novel synchronous current-doubler rectifier (SCDR) method is proposed as an LED driver. The reasonably designed circuit is used to control the output voltage ripple in the normal range without adding a complicated control circuit. The proposed topology is designed using few components, has no electrolytic capacitor, and has a low cost for high-output current LED driver applications. Circuit operating principles and detailed theoretical analysis are provided in this paper. A 200-W prototype has been established and tested, and the experimental results are presented to highlight the merits of the proposed circuit.

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