EMTP modeling of IGBT dynamic performance for power dissipation estimation

A new approach to the modeling of insulated gate bipolar transistors (IGBT's) for electromagnetic transients program (EMTP) simulation is developed. Other commercially available simulators, such as PSPICE, model the devices on an exact semiconductor physics basis. They suffer from large amounts of CPU time for sinewave pulsewidth modulation (PWM) inverter applications which require a complete cycle simulation at fundamental frequency with a small time step to cover the details of IGBT switching transients. This approach uses a curve-fitting method, combined with the point-by-point user-defined function available in EMTP, to model the dynamic characteristics of IGBT's. Since there is no device physics modeling required, the simulation is much faster than the conventional approach. The proposed method is applicable to both static and dynamic modeling, on a cycle-by-cycle basis, which is important for dynamic power dissipation and thermal analysis. The simulation includes IGBT turn-on and turn-off transients, IGBT saturation, free-wheeling diode forward voltage, and reverse recovery characteristics. The simulation results are verified by comparison with experimental measured data. Measurements show a close agreement with simulations.