热学特性是影响功率型LED光学和电学特性的主要因素之一，设计了一套基于脉冲式U-I特性的功率型LED热学特性测试系统，可以测试在不同结温下LED工作电流与正向电压的关系，从而获得LED的热学特性参数。该系统通过产生窄脉冲电流来驱动LED，对其峰值时的电压电流进行采样，同时控制和采集LED的热沉温度，从而获得不同温度下LED的U-I特性曲线。与其他U-I测试系统相比，文中采用了窄脉冲(1 μs)工作电流，LED器件PN结区处于发热与散热的交替过程，不会造成大的热积累，大大提高了测量精度。实验中，对某功率型LED进行了测试，获得了该器件的电压、电流和结温特性曲线，并利用B样条建立该器件的U-I-T模型，进而实现了对其结温的实时在线检测。

Thermal performance is one of the main factors which affect the optical and electrical performance of high power LED. The thermal performance testing system for high power LEDs based on voltage-current characteristics with pulse injection was designed in this paper, which can test the relationship between the operating current and forward voltage of LED under different junction temperatures, thereby obtaining LED thermal characteristics parameters. The system worked by generating a controlled narrow pulse current to drive the LED, and sampling the peaks of voltage and current of LEDs with LED heat sink temperature control and acquisition, thereby obtaining the voltage-current characteristic curve in different junction temperatures. Compared with other voltage-current testing systems, the designed system adapts the narrow pulse duty cycle(1 μs), so the PN junction of LED devices is always in the process of alternately heating and cooling, which can avoid large heat accumulation and greatly improve the accuracy of measurement. In the experiment, a power LED device was tested by the system and the voltage-current-temperature curve was obtained. Then the B-spline based U-I-T model of the LED was established, so the real-time online detection of LED device was achieved.