碳化硅器件建模与杂散参数影响机理

为了更准确地评估碳化硅宽禁带半导体功率器件的性能和系统特性,需要搭建不同封装下器件的快速行为仿真模型,包括静态特性模型与动态响应模型。首先基于MOSFET器件EKV模型,舍去了原模型的漂移区电阻并赋予参数温度自由度后,实现一种仅需要器件数据手册的快速建模方法。对比原静态模型,改进模型收敛速度更快;器件转移特性和输出特性拟合精确度有明显提高;不同结温的静态特性可独立建模。其次,基于静态模型参数,校正了寄生电容和跨导,加入模块封装和层叠母排的杂散电感和分布电容参数,分阶段建立了开关过程中驱动回路和主回路微分方程,给出了器件杂散参数提取过程以及漏极电流、端电压的动态响应求解方法。最后搭建碳化硅功率模块双脉冲实验电路,结果显示模型可真实重现开关过程中的电压电流尖峰与振铃细节。

Modeling of SiC power device and study of nonlinear stray parameters impact

For accurately estimating wide bandgap silicon carbide power device characteristic and system performance,fast and accurate behavioral static and dynamic model under discrete and module packaging should be built.Firstly,a modified EKV static model was built using only curves from datasheet.Compared with the original model,the proposed one removed the drift region resistance and applied temperature degree of freedom to all parameters.As a result,the proposed model showed faster convergence speed and significant improvement on fitting transfer and output characteristics,enabling independent modeling under different temperatures.Secondly,an analytical dynamic model was set up based on static model parameters.Parasitic capacitance and nonlinear transconductance were specially modified,packaging and laminated busbar stay parameters were taken into consideration.The differential equations of the driving loop and the main loop in switching process were established by stages,and the solution of drain current and node potential and extraction method of the analytical model were given in detail.Experiment results from double-pulse test were applied to verify the proposed model,great fitness was seen with the overshoot and ringing of node voltage and drain current.