考虑变温度影响的SiC MOSFET建模与分析

为了准确反映SiC MOSFET在不同温度下的电气特性,对影响SiC MOSFET电气特性的关键参数进行了分析,提出了一种SiC MOSFET等效电路模型。首先,根据SiC MOSFET阈值电压和跨导随温度变化的规律,采用函数拟合的温控电源模型对SiC MOSFET的阈值电压和漏极电流进行补偿;其次,考虑寄生电容与极间电压的关系,采用电容子电路和可变电容模型对SiC MOSFET的寄生电容进行等效模拟,根据SiC MOSFET体二极管对其静、动态特性的影响,利用独立二极管模型描述体二极管特性,进而建立SiC MOSFET的等效电路模型。最后,在不同温度条件下,对该模型进行了仿真并与实验测试结果进行了对比。结果表明所建模型较为准确地描述SiC MOSFET在较宽温度范围内的静、动态特性,验证了模型的有效性。

Modeling and Analysis of SiC MOSFET Considering Variable-temperature Effect

To accurately reflect the electrical characteristics of silicon carbide(SiC) MOSFET at different tempera-tures, the key parameters affecting its electrical characteristics were analyzed in this paper, and a novel equivalent circuit model of SiC MOSFET was proposed. Firstly, according to the temperature-dependent rules of SiC MOSFET''s threshold voltage and transconductance, the threshold voltage and drain current of SiC MOSFET were compensated by the temperature-controlled power model based on function fitting. Secondly, considering the relation of parasitic capacitance versus the voltage between electrodes, the parasitic capacitances of SiC MOSFET were equivalently simulated by the model of sub-circuits and variable capacitances. Besides, according to the influences of SiC MOSFET''s body diode on its static and dynamic characteristics, its novel equivalent circuit model was established by using the model of independent diode to describe the characteristics of the body diode. Finally, this model was simulated at different temperatures, and the simulation results were compared with the experimental data, showing that the novel model can more accurately reflect the static and dynamic characteristics of SiC MOSFET in a wider temperature range. Therefore, the validity of the proposed model was verified.