Simulation Research On Application Of Thermoelectric Cooling Technology In LED Thermal Management

LED is a light source with high luminous efficiency,high service life.It quickly occupied the lighting market in the early 20th century.However,highpower LEDs have high heat generation and high heat flux density,resulting in high temperature in the pn junction of high-power LEDs,which greatly reduces the use effect and lifetime of LEDs.The existing LED heat dissipation methods still cannot totally reduce the pn junction temperature to the safe temperature,which limits the research and application of high power LEDs.Thermoelectric cooling technology is a kind of heat transfer effect which transfers heat from a low temperature zone to a high temperature zone.It is characterized by an inverse temperature difference along the heat flow direction,which can effectively reduce the temperature of electronic components in the field of electronic heat dissipation.In this paper,the application of thermoelectric cooling technology in LED thermal management is studied.The work includes the establishment of a thermal resistance model containing thermoelectric cooling based on the basic theory of heat transfer and thermoelectric effect.The thermal resistance model is compiled by Matlab software to study the relationship between thermoelectric cooling parameters needed by thermoelectric cooling technology and LED junction temperature reduction effect,combined with ANSYS simulation to study the junction temperature reduction effect of thermoelectric cooling applications on high-power LED headlights.The main contents and results are as follows:(1)An LED thermal resistance model with or without thermoelectric cooling structure is established.And the corresponding LED junction temperature equation is derived.Through the thermal resistance model and the junction temperature equation,the minimum number of thermoelectric arm pairs and the range of thermoelectric cooling input current required for thermoelectric cooling to reduce the junction temperature of the LED are obtained;and the thermoelectric cooling input current value corresponding to the minimum junction temperature of the LED is found.The analysis model shows that:The maximum heat sink thermal resistance required for thermoelectric cooling to reduce the LED junction temperature increases with the increase of the number of thermoelectric arm pairs;LED junction temperature reduction value increases with the decrease of heat sink thermal resistance,and increase with the increase of the number of thermoelectric arm pairs;the COP of thermoelectric cooling decreases with the decrease of heat sink thermal resistance.When the LED input power is 25W and the ambient temperature is 25℃,the minimum number of thermoelectric arm pairs is 45 pairs;when the number of thermoelectric arm pairs is 150 pairs,the maximum LED junction temperature reduction value is 40.89℃.(2)The thermal resistance model is used to study the influence of the minimum number of thermoelectric arm pairs,the maximum heat sink thermal resistance,the LED junction temperature reduction value and the COP of the thermoelectric cooling which are required for the thermoelectric cooling to reduce the junction temperature of the LED.The results show that minimum number of thermoelectric arm pairs decreases with the increase of ambient temperature,and the maximum heat sink thermal resistance and LED junction temperature reduction value and the COP of thermoelectric cooling increase with the increase of ambient temperature.When the LED input power is 25W and the ambient temperature rises to 55℃,the minimum number of thermoelectric arm pairs decreases to 37 pairs;when the number of thermoelectric arm pairs is 150 pairs,the maximum LED junction temperature reduction value is 51.62℃..(3)A 30W high-power LED headlight was selected,and the temperature distribution of the LED lamp and the LED junction temperature of the lamp under different heat dissipation conditions(ambient temperature and wind speed)were simulated by ANSYS software.The results show that when the ambient temperature is higher than 50℃ the maximum LED junction temperature cannot be reduced below 110℃ by forced convection.According to the simulation results,the thermal resistance model of the high-power LED lamp is established,and it is determined that the thermoelectric cooling structure for the LED lamp has 130 pairs of thermoelectric arms.Calculate the junction temperature of the LED headlight with thermoelectric cooling structure.The calculation results show that the thermoelectric cooling structure can reduce the junction temperature to 97.47℃ at an ambient temperature of 50℃,and the junction temperature can be reduced to 106.51℃ when the ambient temperature is 60℃.