Multi-objective methodology to find the optimal forward current to supply light emitting diode (LED) lightings

Light emitting diodes (LEDs) are commonly expected to be the future of lighting because of a high luminous efficacy, a long lifetime and a high color rendering index (CRI). Nevertheless, the performance and the reliability of an LED are strongly dependent on the LED junction temperature. This paper presents a multi-objective methodology to find the optimal forward current subject to the annualized cost of the luminaire (initial capital cost, replacement cost, operation and maintenance cost...) and the annualized energy consumption. A simple LED model based on empirical data has been developed and takes into account optical, electrical, thermal and ageing behaviour. Three different white LEDs have been evaluated through several combinations of forward currents and heatsinks to satisfy a given mission profile. A set of optimal solutions has been determined by Pareto optimization.