An Accurate Power Loop Stray Inductance Extraction Method for SiC MOSFETs Based on Forced Resonance With Decoupling Capacitor

To better instruct the optimal operation of silicon carbide mosfets in converters, accurate estimation of the power loop stray inductance is essential, preventing unacceptable voltage overshoots and EMI noises during switching transients. This letter presents a stray inductance extraction method based on forced low-frequency resonance of the target stray inductance and the dc-link decoupling capacitance, which can be skillfully triggered by applying a switch in the dc bus. An ideal resonant tank can be created by selecting a Class I ceramic capacitor as the stable decoupling capacitor, enabling the precise result to be calculated. The extraction accuracy of this proposed method is verified through experiments, showing a relative error of 2.9% compared with the measurement using a professional impedance analyzer E4990A. Furthermore, unlike existing methods relying on high-frequency resonance with device junction capacitance at the fast-switching ringing stage, this method only requires low bandwidth test equipment, making it attractive for applications limited by costly measuring probes.