Thermal Model Design and Analysis of High-Power LED Headlamp Cooling Device Based on the Thermoelectric Effect

In view of the characteristics of high-power light-emitting diodes (LEDs), such as strict junction temperature (Ti) control, the enhanced cooling models based on the thermoelectric cooler (TEC) were presented to meet the thermal demand of high-power LED headlight. The cooling performance of different devices (air cooling and TEC, and liquid cooling and TEC) was evaluated and compared by measuring the LED case temperature. The details of the heat transfer performance, particularly, the startup performances of the TEC cooler as well as the influence of the fan rotate speed or liquid velocity on the system thermal performance, were obtained. It was found that the thermal performance had been elevated dramatically due to the reduction in hot-side temperature, and the TEC was more sensitive to the external fan speed or liquid velocity than purely air cooling or liquid cooling. In addition, the optimal current for air cooling and TEC was 3 and 5 A for liquid cooling + TEC. The investigations of the simulated ambient temperature on junction temperature, forward voltage, and output light were conducted. The results indicated that the case temperature changed linearly basically with the increase in heating power or the simulated ambient temperature. When the ambient temperature was within its severe level (60°C-65°C), the junction temperature could be calculated to 59.5°C, and the corresponding output light was 1607.3 lm.