The effect of bipolar transistor in the switching dynamics of IGBTs in resonant converter applications

This paper reports on extensive experimental and theoretical characteristics of Insulated Gate Bipolar Transistors (IGBTs) for resonant converter applications. It is shown that di/dt dependent dynamic forward voltage saturation occurs due to conductivity modulation lag in the drift region caused by high concentration of deep-level impurities. During turn-off, temperature and dv/dt dependent elevated tail current bump was measured that is caused by the minority carrier recombination effects in the drift region. The physical mechanisms causing this anomalous behavior are studied using advanced mixed device and circuit simulators. It is shown that bipolar carrier transport mechanisms place important constraints on tradeoff among the performance and Safe-Operating Area parameters.