换流回路的寄生参数对碳化硅MOSFET开关特性的影响

Influence of Parasitic Parameters of Commutation Path on Switching Characteristics of Silicon Carbide MOSFET

为有效评估换流回路的寄生参数对碳化硅MOSFET开关特性的影响,首先建立了考虑换流回路寄生参数的完整的碳化硅MOSFET开关暂态电路模型,该模型考虑了换流回路负载电感的寄生电容,并将换流回路的寄生电感分为二极管支路电感和其他串联电感两部分,基于所建立的模型分析了器件的开关特性。然后搭建了碳化硅MOSFET动态特性测试平台并提取了对应的等效电路计算模型,通过解析与计算模型的结合分析了换流回路各部分寄生参数对碳化硅MOSFET开关特性的影响。最后通过实验验证了分析结果的正确性。结果表明,在考虑负载电感寄生电容的情况下,换流回路中二极管支路电感与其他串联部分电感对碳化硅MOSFET开关特性的影响不同,且二极管支路电感对关断电压过冲的影响更大。在此基础上,针对电压过冲与绝缘击穿问题,对高压碳化硅MOSFET动态特性测试平台的布局优化与寄生参数设计提出建议。

To accurately access the influences of the parasitic parameters of the commutation path on the switching characteristics of the silicon carbide MOSFET,a complete model of silicon carbide MOSFET switching transient circuit in which the parasitic parameters of the commutation path are taken into consideration is established.In the model,the parasitic capacitance of load inductance of the commutation path is taken into consideration,and the parasitic inductance of the commutation path is divided into the diode branch inductance and the other series inductance.Based on the new model,the switching characteristics of the device are analyzed.Then a test platform for the silicon carbide MOSFET device dynamic characteristic is built,and the corresponding equivalent circuit calculation model is extracted.Through the combination of analytical analysis and calculation model,the influences of the parasitic parameters of each part of the commutation path on the silicon carbide MOSFET switching characteristics are analyzed.Finally,the correctness of the analysis results is verified by experiments.The results show that when the parasitic capacitance of the load inductor is taken into account,the diode branch inductance and other series inductances in the commutation path have different effects on the switching characteristics of the silicon carbide MOSFET,and the effect of the inductance of diode branch on turn off voltage overshoot is more remarkable.Based on this,the layout optimization and parasitic parameter design of the high voltage silicon carbide MOSFET dynamic characteristic test platform are proposed for the problems of voltage overshoot and insulation breakdown.