高功率LED熱逸散因子之實驗量測研究

Experimental Investigation of Heat Dissipation Factors for High-Power LEDs

黃正宏(Zheng-Hong Huang)

指導教授 ： 周榮源

國立虎尾科技大學/工程學院/機械設計工程研究所/碩士(2013年)

摘要

散熱問題一直以來都是高功率LED使用上需要被克服的一大議題。高功率LED在提供較高的光通量同時，亦會產生大量的熱能，其接點溫度的提高，使LED光通量大幅降低，亦會影響LED的可靠性與使用壽命。
熱逸散因子Kh，被定義為輸入電功率所產生的熱能。若能精確的獲得Kh值，將有助於定義與分析LED於照明中的熱特性。在本研究中，提出一實驗量測方法量測熱逸散因子。改變LED輸入功率，利用儀器擷取並記錄實驗中暫態過程到穩態的變化。實驗結果顯示，兩種不同品牌之LED其熱逸散因子不相同，其光通量亦受到熱逸散因子的影響。利用此一簡單量測方法得到熱逸散因子可計算出理論光通量，與由正向電流模型和接點溫度模型計算出之光通量相較，其誤差值低於10%。由此可知熱逸散因子將有助於設計與探討LED之光、電、熱之耦合特性。

關鍵字

熱逸散因子 ； 高功率LED ； 量測方法 ； 光通量

並列摘要

Heat generations were inevitable transport phenomenon of high-power LED lighting. While high-power LEDs in operation can produce high luminance, but they also generate significant heat at the same time. The optical output of the LED is sharply degraded with the increase in junction temperature because the high temperature significantly influences the reliability and durability of the LED.
The heat dissipation factor, Kh, for a lighting device is defined as heat dissipation from the lighting to total electrical input power of the lighting. It will be beneficial and critical to modeling and simulate thermal designs of lighting if the Kh factor of the specific LEDs is precisely obtained. In this study, a methodology is proposed and experiments are conducted to find the LEDs heat dissipation factors. Experiment procedures are changing the input powers to LEDs, and then gathering information by related instruments for the whole transient to steady states. Experimental results showed that, for two different brands of LEDs under test, different values of heat dissipation factor were found, and the optical outputs of luminous flux were affected by the value of heat dissipation factor. By using the simple method to measure the heat dissipation factor, the theoretice luminous flux can be evaluated; and comparing it to the luminous flux evaluated by the method of using a forward current model and a junction temperature model, the absolute error between these two results is less than 10%. It is expectable that the measured Kh factor will be helpful to thermal designs and characterizations of optical-thermal interdependence of LED lightings.

並列關鍵字

Heat dissipation factors ； High-power LED ； Light intensity ； Experimental measure

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