Improved Extraction of Parasitic Common-Mode Capacitances in IGBT Modules Based on Resonance of External Inductor

Half-bridge insulated-gate bipolar transistor (IGBT) modules are widely used in power electronic devices, and the high-speed switching of IGBTs in the modules can cause serious electromagnetic interference (EMI) through parasitic common mode (CM) capacitances in modules. Therefore, accurately extracting the parasitic CM capacitances of IGBT modules is significant for modeling and evaluating the EMI of power electronic equipment. Considering that the original extraction based on the resonance of the external inductor is affected by using asymmetric terminal measurements, this letter proposes an improved extraction method for parasitic CM capacitances of IGBT modules. The calculation method for parasitic CM capacitances of IGBT modules based on impedance measurement is presented. The impact of nonlinearity in junction capacitances during impedance measurements is greatly eliminated. The improved method is validated through measurements.