Model for Conducted Emission of SiC Power Modules for automotive traction Inverter-Comparison to behaviour-based Model

This paper presents a simulation approach to predict conducted electromagnetic emission of silicon carbide power modules applied in automotive inverters for electric drivetrains. The proposed time domain model is developed for standard circuit simulators and is directly adapted to the standardized measurement procedure of CISPR 25 from 150 kHz to 108 MHz. The main purpose of the paper and the presented model is, to verify the quality, the accuracy and the level of confidence of a faster, behaviour-based approach, which uses idealized switching transients instead of detailed semiconductor models. Thus, the focus is on the detailed modeling of the power modules, the semiconductors and their switching behaviour, but not on the overall inverter characteristics. As a consequence the inverter is reduced to a buck converter. For the silicon carbide semiconductors, the provided accurate supplier MOSFET models are used. The electric environment of the converter is modeled by simplified equivalent circuits. Besides the differences due to the smoother waveforms of the accurate MOSFET models, the great impact of the voltage dependent drain source capacitance is identified and analysed. This results in a non-linear system behaviour. Finally, the model and the findings are verified by measurements.