Differential-mode oscillations between parallel IGBTs in power modules

Large IGBT modules often consist of many IGBTs connected in parallel in order to achieve high current ratings. In the ideal case, current is shared equally between these IGBTs. However, in real power modules parasitic oscillations between the IGBTs can occur, which can lead to EMC issues or even damage the power module. In this paper, two different oscillation circuits are presented which have been observed in different power modules. Only self-exciting, differential mode oscillations are treated in this work. Measures to reduce or avoid these oscillations are discussed. As one technique to analyze the properties of the oscillations, the stability of the circuits is analyzed by calculating the poles of linearized networks.