Taylor-Series-Expression-Based Equivalent Circuit Models of LED for Analysis of LED Driver System

This paper presents the Taylor series expression based light-emitting-diode (LED) model for the analysis of the LED driver system. In order to precisely describe the nonlinear V -I curve of LEDs, Taylor series can be utilized to express the Shockley equation of LEDs for the derivations of the dc and small-signal equivalent models. Based on the proposed LED models, the LED array with M paralleled strings of N LEDs in series can be constructed. Furthermore, the equivalent resistances of the N × M LED array can be derived. Finally, one LED array with eight paralleled strings of 15 LEDs in series is constructed to verify the equivalent small-signal resistance with the measured results.