Turn-on oscillation damping for hybrid IGBT modules

In a hybrid IGBT module with SiC diodes as free-wheeling diodes, high frequency oscillation occurs during turn-on due to the fast switching transient of SiC diode and the resonance between circuit parasitic inductances and the junction capacitance of SiC diode. Such oscillation causes EMI noise which may affect the performance of the system. Methods to mitigate the turn-on oscillation are studied. Firstly, the effect of gate drive parameters on turn-on oscillation is investigated with respect to different gate voltages and gate charging currents. Then a novel turn-on oscillation suppression method is proposed with combination of damping circuit and active gate driver. The proposed oscillation suppression method can achieve the lowest EMI noise while remaining the advantage of lower switching loss brought by SiC diodes. Detailed theoretical analysis of the turn-on oscillation is conducted, and experimental results are given to verify the effectiveness of the proposed oscillation suppression method.