A model of a LED for street illumination — Simulations and measurements

The goal of this paper is to find the best model for LEDs used in simulations for street lighting. The model of LED has three parameters: V_LED, I_LED and R_LED. First, it is presented a model of LED extracted from the I-V characteristic given in the datasheet of producer. This model will be called MDS (Model from the Data Sheet). Secondly, for the same LED the I-V characteristic is raised through measurements. After the equation is established, the parameters of the LED are calculated with simple equations; this model is called MPM (Model Proposed from Measurements). The third model is obtained from averaging the measurements of parameters values for many series LEDs; this model is called MPA (Model Proposed from Averaging). All models are introduced in simulations. After that, the results are compared with the measurements. The errors obtained with the model proposed MPM are less than the errors obtained with the MDS and MPA model. This model is the best for simulations. The LED used in this paper is OSLON SSL 150 from OSRAM. The parameters of MDS are: V_LED=2.944V, I_LED=350mA and R_LED=555mΩ. The parameters of MPM are: V_LED=2.934V, I_LED=350mA and R_LED=642mΩ. The errors with the MDS are less than 13.33%, and with the MPM are less than 7.88%. The errors with the MPA are less than 25%. For simulations and measurements is used the driver MP4021A from Monolithic Power Systems (MPS) for two parallel strings of 16 series LEDs (32W). The software used is MPSmart 7.20 from MPS and for measurements are used Fluke 8808A digital multimeters.