Intrinsic Propensity of IGBTs to High-Frequency Short-Circuit Oscillations

摘要

TCAD device simulations of a circuit with just one IGBT structure, an ideal driver and an ideal DC-link voltage source demonstrate that IGBTs may have an intrinsic propensity to high-frequency short-circuit oscillations (SCOs). Simulations of a one-dimensional n-p-n-p structure without a classic MOS gate reveal that the fundamental oscillation mechanism is caused by the periodic storage and release of charge carriers across the device, and not by a varying charge accumulation at the silicon-oxide interface. Simulations with different IGBT structures and corresponding n-p-n-p structures show a comparable voltage range with short circuit oscillations, which verifies that the occurrence of high-frequency short-circuit oscillations depends strongly on the vertical distributions of the charge-carrier densities and the electric-field strength in the drift zone.