The Average Junction Temperature Test Method And Thermal Analysis For LED Lamps

LED is a new kind of semiconductor light source. It has many advantages, such as, high brightness, high reliability, long life, energy saving environmental protection and small size. Therefore it is also known as the fourth most promising generation lighting source in twenty-first Century. In recent years, with the development of LED lighting technology and the national policy to support the promotion of high power, LED has become the main tool to satisfy people's need for brighter light. With the increasement of the power of LED devices, the LED light's chip junction temperature is also increasing. Therefore, the electrical characteristics, reliability and service life of the LED are seriously affected. And the thermal performance of LED has been the main problem to limit the development of the LED industry.Junction temperature and thermal resistance are the important index of the thermal characteristics of LED. The traditional measurement method is to measure the whole LED lamp or average thermal performance, for example the overall thermal resistance. We cannot test the inner structure of LED lamp, such as thermal resistance of each layer. Therefore, we can not make a definite analysis about the thermal design of LED lamp and get the best design. Or we must contribute more time and energy to get a better design. The paper makes an analysis about thermal characteristics of the LED devices and makes an accurate test of the thermal resistance and the heat capacity in each heat conduction path layer. And the paper makes a comprehensive evaluation about the thermal performance of LED products. Therefore it plays an important role in redesigning the product. At the same time, it provides thermal standards for LED enterprises for production.There are mainly six parts in this paper.1. It generalizes the thermal problems in LED industry and the traditional LED junction temperature test method.2. The paper analyses the main method to test LED devices and the thermal performance of lamps-- electrical parameter method. And it makes an analysis about the structure theory of thermal characteristics and the thermal resistance network model.3. The author tests the LED device and the K coefficient of the lamps. And the author makes an analysis about the K coefficient under different electrical connection situation. As a result, the author find the easy and convenient way to test the equivalent K coefficient of LED lamps and devices.4. The author designs LED bulb light source module and experiments to compare the bubble lamp thermal characteristics. The author also used the T3 Ster instant resistance instrument and T3 ster master software to test and analyze the data and got the structure function curve of the sample. At the same time, the author adopted the infrared thermal imaging method to test the light source component junction temperature. The experimental results verify the certainty of the accuracy of the testing method. It plays a guiding role in redesigning and optimizing thermal instrument with the combination analysis of the thermal curves.5.The paper analyzes the changes of internal thermal characteristics under different temperature and wind speed. At the same time, it analyzes the maximum thermal power capacity of LED bulb lamp and compares the thermal software.6. It also optimizes the LED lamp radiator structure and adopted the Solid Works and FLOEFD to make a structure modeling and simulation analysis about the difference between the former and the optimized one. To analyze the former lamp heat dissipation, we find that the temperature of the connected zone of the fin and the radiator body is high and the cooling effect is not good. We open up the Fin radiator body parts to solve the problem. It is better for the heat radiation compared with the former one. What's more, the optimized one saves the material.