Dr. Mihil Kruger, an expert at Philips Lumileds, recently published an article on accurate and efficient calculation of LED heat, detailing the accuracy and sensitivity of white LED thermal analysis. process. The following is the full text of the article published by Dr. Mihil Kruger.
Today, thermal analysis of white LEDs is still an unfinished science. Most LED luminaire and luminaire manufacturers can only rely on insufficient, inaccurate or ambiguous data to determine the performance of LED devices in related applications, which can often lead to over-engineering their heat sink designs.
Power conversion efficiency (WPE) methods are commonly used in the industry to calculate the power required to convert an LED into optical radiation, as well as the amount of heat actually produced by the LED. The drawback of WPE is that the results obtained between LED devices in the same product category vary widely, making it difficult for luminaire and luminaire manufacturers to compare LED products . Moreover, WPE usually has a lot to do with the operating environment. We will introduce a simple and clear calculation method based on radiant luminous efficiency (LER) for LED calorific value. The LER of the most advanced, fluorescent-converted white LEDs is generally kept constant, so illuminator designers can use this formula to quickly estimate the amount of heat generated by LED devices.
LED and heat dissipation
In thermal simulation experiments, LEDs are sometimes modeled as simple resistive heaters, and all electrical power that enters the LED is assumed to be converted into heat and conversely dissipated from the illuminator. But there is a problem with this assumption, that is too conservative: high-brightness fluorescent-converted white LEDs typically convert 30% of incoming electrical power into light, while royal blue LEDs can convert power by much more than 50%. Therefore, the total power required to heat a high-brightness LED is typically lower than the total electrical power entering the LED.
LED definition
Distribution of WPE and LER
Comparison of WPE and LER
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