Analysis of Frequency Characteristics of Parasitic Inductance in Power Modules and Methodology for Selection of Frequency Point

The parasitic inductance greatly impacts the characteristics of power modules, which can cause voltage spikes and oscillations. Extracting the inductance accurately is of great significance in guiding the layout design and application of power modules. The parasitic inductance is frequency-dependent owing to the skin effect and proximity effect. However, most methods ignore this phenomenon and utilize a single frequency point to extract the commutation inductance. This paper proposes a frequency-chosen method to extract the parasitic inductance and guide the users on how to extract the correct inductance by selecting the proper extraction frequency. First, finite element method (FEM) simulation is applied to extract the inductance of power modules. Then, the turn-off process of power devices is analyzed and the equivalent excitation frequencies are calculated. The proposed method utilizes the principle of the equalization of the excitation and oscillation frequencies to obtain the correct inductance. Finally, the double pulse tests are conducted to verify the effectiveness of the proposed method.