Optimal Design of Passive Light-Emitting Diode (LED) System

Abstract

Existing LED driver usually consists of semiconductor switches, electrolytic capacitors and control board. These will increase the circuit complexity and reduce the energy efficiency and stability of the circuit. Therefore, new design of Passive Light-Emitting Diode (LED) driver is introduced. It only uses 11 components including 2 inductors, 2 capacitors and 7 diodes. It can provide a smooth current from ac power supply to drive LED strings. Also, this LED driver has the advantages of high power efficiency, longer lifetime and environmentally friendly. To confirm the validity of the design, both series and parallel LED strings are verified by experiments. In addition, a feedback assisted Self-configurable current mirror circuit is applied to further optimize the parallel LED strings. Furthermore, a photo-electro-thermal theory is used to increase the luminous flux and reduce the LED flux changes. High power efficiency of series and parallel LED strings are achieved 95.16% and 91.06% respectively.