Switching ruggedness and surge‐current capability of diodes using the self‐adjusting p emitter efficiency diode concept

Abstract

The surge-current ruggedness of freewheeling diodes can be improved by implementing the self-adjusting p emitter efficiency diode concept (SPEED). Simulations indicate that the switching ruggedness is reduced because of the occurrence of cathode-side filaments during reverse-recovery. Experiments confirm the weak switching performance of such a diode in comparison to a conventional diode. By implementing the controlled injection of backside holes concept cathode-side filaments can be suppressed. However, this measure is not sufficient to regain the switching ruggedness of a conventional diode. It is also necessary to fully embed the p +-areas of the SPEED anode in the low-doped p-type area to avoid high electrical field strengths at the p + p-junction and pinning of anode-side filaments. However, anode-side adjustments for improving the switching ruggedness can reduce the benefit of the SPEED concept regarding the surge-current capability.

Protection Scheme for Modular Multilevel Converters Under Diode Open-Circuit Faults

“…The diode open-circuit fault may occur owing to various reasons, e.g. overcurrent, high temperature fatigue, and mismatch of coefficients of thermal expansion between silicon and aluminum [24][25][26] would result in bond wire lift-off failure and cause diode open-circuit fault, which is one of the important fault issues for MMCs [14] and may seriously affect the performance of the MMC. In this paper, the fault characteristics of the MMC under diode open-circuit fault are analyzed and an effective protection scheme is proposed.…”