基于寄生参数的功率MOSFET数学建模及损耗分析

Mathematic Modeling and Loss Analysis of Power MOSFET Based on Parasitic Parameters

为了精确地描述功率金属氧化物半导体场效应管(MOSFET)的开关特性,建立了一种基于MOSFET的寄生参数(Miller电容和寄生电感)的数学模型。该模型中采用拟合法分别构建Miller电容的数学表达式和转移特性的数学表达式,并详细推导了开关过程中电压和电流的数学表达式。针对关断后出现的电压、电流振荡建立的物理等效电路进行了分析。越精确的电压和电流数学表达式越能准确地反映功率MOSFET的开关损耗。仿真实验验证了本文数学分析模型和物理等效电路的正确性和有效性。

In order to accurately describe the switching characteristic of power metal-oxide semiconductor field-effect transistor （MOSFET）, a model based on parasitic parameters （Miller capacitance and parasitic inductance） was proposed in this paper. The mathematical expressions of both Miller capacitance and transfer characteristic were established by means of fitting method, respectively, and the mathematical expressions on voltage and current were also derived in detail. Moreover, the analysis on equivalent physical circuit was made for the voltage and current oscillation after being turned off. The more precise both voltage and current mathematical expressions are, the more accurate the reflection on loss of power MOSFET is. The simulation results verify the effectiveness of the proposed mathematical analysis model and equivalent physical circuit.