High-power LEDs created a center of attention due to their applications in energy-saving lighting systems, display, and many other fields. Therefore, the optical and electrical characteristics of LEDs at forward bias have a significant research value [1,2]. And majority of research papers on the characteristics of LEDs focuses on their optical and electrical properties under the DC mode. However, more requirements on LED illumination under the AC condition is undoubtedly increasing due to the emerging AC LED systems into the market these days. It is generally known that the AC driving is more efficient way of generating and transmitting power systems compared with the DC mode. With proper design considerations, LEDs can be driven more efficiently under AC operation than under DC operation. By this reason, there found some
research activities recently on the AC driven LEDs [3,4]. However,
most of researches on AC driven LEDs focus on circuit design issue
and it is hardly found reports on thermal behavior of LEDs under
the AC operation.