High Power LED Parametric Modelling Using a Double Polynomial Approximation

K Zaplatílek,J Leuchter

doi:10.3849/aimt.01174

Abstract

This article describes calculations for an accurate mathematical model of high power LED modules using double optimal polynomial approximation. The model is based on unique tests of various LED types in a thermal chamber, providing a comprehensive list of parametric temperature profiles. This model was then implemented into MATLAB®&Simulink® and Micro-Cap programs as a Spice compatible electronic circuit model, utilising the newly created algorithm. To define an optimal degree of approximation polynomials, Euclidean norm of residues was used. The new algorithm described in this article was verified using real-life data tested at the author’s work site, where the corresponding research takes place. To maximise the test’s efficiency, an automated data collection system was created. This article describes one particular tested LED module whose characteristic was modelled in both the absolute and the normalised form for easy comparison.

Highlights

High power LED modules have started to spread into many scientific fields and industries
The analysis has proved that the total optimal degree of the approximation polynomials is nopt = 5 (‒)
This article described the creation of a brand new algorithm for modelling high power LED modules using double optimal polynomial approximation

Summary

Introduction

High power LED modules have started to spread into many scientific fields and industries. There are many articles focusing on model identification and their optimisation [6,7,8,9] None of these resources, known to us so far, focus on approximation of thermal characteristics of these high power LED modules. The method for creating the model in this study is based on extensive tests of the high power LED modules in Vötsch VC3 7034 thermal chamber. The purpose of the below described algorithm is to calculate a random operating point COP (Calculated Operating Point) in a particular plane, i.e. to determine illumination E0 for a user-defined temperature T0 and an electrical current I0, see Fig. 1 It is done by performing double approximation using optimal polynomial.

Basic Principle of Creating the Model

IT Approximation

Model Implementation in Simulink Environment

Model Implementation in Spice Oriented Circuit Simulator

Conclusion