Thermal Uncertainty Simulation on LED Lighting Boards of Heavy Duty Transportation Vehicles

Abstract

Lighting of heavy duty vehicles like trucks, buses and trains has been mainly implemented with fluorescent lamps and inverters, and is being now upgraded to LED (Light Emitting Diode) new technology. Given the normative lighting requirements (measured in lux), added to the aggressive environment of automotive application and its specifications, the high flux, improved efficiency mid and high power LED's are becoming the most practical and smart solution for city and coach transportation. One of the relevant factors on PCB design of LED lighting is LED junction temperature, which depends on the type of power supply employed, pad temperature and construction factors. This paper aims to shows the uncertainty on junction temperature measurements through Monte Carlo method. This technique uses randomly generated input variables in a mathematically built model (plant), to obtain the combined uncertainty output estimation. After the evaluation of all uncertainty factors that influence the LED and its switched power supply's thermal behavior, the model is extensively simulated showing that the significance of the junction temperature variation is finally taken, in terms of the input manufacturing and environmental parameters