Models for simulation of diode (and IGBT) switchings which include the effect of the depletion layer

A diode model which can be used in a complete circuit with a general-purpose circuit simulation program (KREAN) is developed. The diode is the basis in an IGBT (insulated-gate bipolar transistor) model. This diode model shows a reverse recovery current that is independent both on di/dt and on the voltage at turn off. A dynamic forward voltage drop is also included. This is achieved by including the following mechanisms: carrier injection which modulates the conductivity, carrier lifetime, and a voltage-dependent depletion layer that includes the mechanism of isolating carriers at turn-off with low voltage and giving a tail current at high voltage. Combining two diode models and a MOSFET characteristic in one model, an IGBT model that gets both bipolar and MOSFET currents is obtained, which the authors take as proof of the accuracy of the theory behind the diode model. Laboratory measurements are included to verify the simulations of the IGBTs