由于交流发光二极管（AC-LED）在实际应用中无需交流/直流整流变压器，它的发展越来越被关注。随着器件功率的增大，芯片结温升高，对器件的光通量、光功率及寿命等产生负面影响，所以精确掌握AC-LED的温升规律就成为芯片设计的关键。运用FloEFD有限元软件进行模拟仿真1 W白光AC-LED分别在直流和交变功率驱动下的瞬态热特性，结果表明在加载交变信号情况下，器件结温会以直流信号的结温为中心周期振荡，振荡的频率与输入功率频率相同，但有明显的相位移动。同时，AC-LED在不同的输入功率和频率下的结温变化显示稳态时的平均结温和结温振荡幅度都随功率的增大而线性上升，但随着频率的增大而降低。

Alternating current light emitting diodes (AC-LED) have attracted more and more attentions due to the advantage of free of alternate current (AC)/direct current (DC) converter in practical application. With the increase of input power, the rising junction temperature will have negative influence on the the luminous flux, the optical power, the lifetime and other parameters of LED. Therefore, the understanding of the principle of accurate temperature rise of AC-LED is the key to the chip design. The finite-element analysis software (FloEFD) is used to simulate the transient thermal properties of 1 W white AC-LED driven by DC and AC power respectively. The results show that the junction temperature of AC-LED driven by AC power, fluctuates periodically around that driven by DC power and the fluctuation frequency is the same as that of the input signal, but with an apparent phase shift. Meanwhile, the variation of junction temperature of AC-LED driven at different powers and frequencies shows that the average junction temperature and its fluctuation amplitude increases linearly with the input power at steady state, however, decreases with the increase of frequency.