| Because LED street lamps are gradually becoming smaller and lighter,in order to ensure the light and heat performance of street lamps,COB chips are gradually being applied to street lamps.Based on the existing chip packaging technology and the principle of LED street lamp heat dissipation,this research encapsulates a COB light source with better light and heat performance to meet the needs of street lamp lighting.Then through simulation calculation,the influence of various factors of the radiator on the heat dissipation performance of the street lamp is studied,and the priority order of each factor is comprehensively considered,and the final heat dissipation optimization parameters of the street lamp are obtained.The main contents of the subject are as follows:(1)Based on the existing COB chip packaging technology,several 50 W COB light sources were obtained through experiments,and the influence of soldering temperature,solder paste type and substrate type on the photothermal performance of COB light sources during the chip soldering process was analyzed.The results show that when the soldering temperature is 270 ℃ and the solder paste is Sn96.5Ag3.0Cu0.5,the void ratio of the COB light source is only 5.1%,the junction temperature is 76.52 ℃,and the luminous flux and luminous effect reach 6215.88 lm and 123.58 lm/W,respectively.In addition,the temperature uniformity of COB light sources with different powers is also studied and the life expectancy is estimated through aging tests.The results show that the temperature distribution of the COB light sources packaged in the experiment is uniform and the service life is about 25249 h,which can meet the needs of road lighting.(2)Based on the engineering heat transfer theory,this paper builds a street lamp thermal test platform,and uses the thermocouple temperature measurement method to install the experimentally packaged COB light source on the street lamp radiator to test its thermal performance and influencing factors to verify its usability and actual performance.The result shows that its junction temperature is about 14 ℃ lower than that of traditional street lamps.And when there is no obvious air flow,the heat dissipation effect of the vertical fin radiator is the best,and its junction temperature is only 69.7 ℃.With the continuous increase of air flow rate and the heat exchange of the radiator reaches equilibrium,the street lamp temperature basically no longer changes.The installation angle of the street lamp can be set to 10-15°when in use.In addition,according to the experimental data,the experimental results are verified by simulation calculation and compared with traditional street lamps,and the heat flow,temperature distribution and heat dissipation capacity of different radiators are analyzed.The results also prove that the vertical fin radiator has the best heat dissipation effect.(3)Based on the current street lamp heat dissipation technology and the actual model of the street lamp,the influence of the chip position,the thickness and volume of the radiator base body,the fin height,thickness,spacing and number on the heat dissipation capacity of the radiator is studied by the method of simulation calculation.The fin parameters were optimized by the cross test method,and finally the optimized solution for 100 W COB LED street lights was that the base thickness of the heat sink was 3.5 mm,and the height,thickness,spacing and number of fins were 30 mm,2 mm,12 mm,and 19,respectively.Compared with the initial model,the maximum temperature of the street lamp drops to 59.57 ℃,and the heat dissipation effect is significantly improved. |
