一种连续函数描述的高精度SiC MOSFET模型

A High-Precision SiC MOSFET Model with Continuous Function Description

传统SiC MOSFET模型为提高精度,通常采用分段函数对不同工作区进行建模,但这带来了模型收敛性不足的问题,难以应用于高频仿真电路。该文提出一种连续函数描述的、具有高精度和强收敛性的SiC MOSFET数学模型。构建单一连续函数描述SiC MOSFET在线性区和恒流区内的静态特性;提出带有收敛电阻的非线性电容模型,并针对不同寄生电容构造相应的拟合函数进行建模;此外,体二极管的建模考虑了结温和栅源电压的影响。仿真结果与手册实测数据的对比分析表明,静态模型仿真结果的皮尔逊相关系数大于0.99,寄生电容拟合的平均相关系数达到0.994 8,体二极管模型与实际伏安特性高度匹配。在室温(TJ=25℃)和高温(TJ=150℃)两种条件下基于C2M0025120D进行了300 V/30 A双脉冲实验,对比验证了仿真模型与实验结果在开断特性方面具有良好的一致性。最后将模型应用在级联H桥多电平逆变器,验证了其在复杂电路仿真中的收敛性。

An accurate and effective SiC MOSFET device model forms the foundation for engineering circuit pre-design and analysis.Currently,most well-developed MOSFET models are based on Si.Due to the differences in their physical structures,Si-based modeling approaches are only partially suitable for SiC MOSFET modeling and often encounter convergence issues.It is noted that most manufacturers'simulation models are comparatively basic and significantly deviate from the genuine features of SiC MOSFETs.This paper proposes a high-precision SiC MOSFET simulation model described by continuous functions to improve accuracy and convergence simultaneously.Additionally,the required data for modeling can be obtained directly from the datasheet,reducing modeling complexity.A method for constructing a continuous function for SiC MOSFET static drain current is proposed based on the shape characteristics of the static characteristic curves.Sub-functions of the model are considered separately based on output and transfer characteristic curve features,and a target function for the model is obtained through mathematical methods.The continuous function model ensures the convergence of the model.Traditional parasitic capacitance fitting functions are improved to address significant slope variations in the transfer capacitance curve that are difficult to fit.An equivalent circuit model for parasitic capacitance with a convergence resistor is proposed.Parameterization is applied to the diode model current source expression,considering temperature and gate-source negative voltage.All these model parameter extraction methods are based on the Levenberg-Marquardt algorithm and a general global optimization method.In addition,accurate extraction of the SiC MOSFET datasheet’s operating curves is required.Comparisons with the operating curves in the datasheet verify the accuracy of the static model.Experimental results from a 300 V/30 A dual-pulse test for C2M0025120D at different operating temperatures(25℃and 150℃)confirm the consistency between the dynamic model and the actual dynamic characteristics.Furthermore,the developed model is successfully applied in a cascaded H-bridge seven-level inverter using PSpice simulation,confirming the model’s convergence.In conclusion,the following findings can be drawn:(1)The model obtained through the proposed static modeling method can accurately describe the actual static characteristics of SiC MOSFET devices.The Pearson correlation coefficient for the static model exceeds 0.99.(2)Introducing the convergence resistor in the parasitic capacitance model effectively improves the model’s convergence.(3)The improved transfer capacitance fitting function can accurately describe the transfer capacitance characteristics,reducing fitting errors.The Pearson correlation coefficient of the fitting is 0.9887.(4)The body diode model considering junction temperature and gate-source negative voltage can enhance model accuracy and applicability.(5)The turn-on errors of the drain-source voltage and drain current are approximately 3%,while the gate-source voltage error is around 8%.