Fault-Tolerant B6-B4 Inverter Reconfiguration with Fuses and Ideal Short-On Failure IGBT Modules

Fault-tolerance is a common measure to improve power electronics availability and to ensure functional safety. A six-switch three-phase voltage source inverter (B6) can be reconfigured to a four-switch three-phase voltage source inverter (B4) with DC link midpoint connection after semiconductor failure. This paper presents a new reconfiguration method without active switches for ideal short-on failure IGBT modules via diodes and fuses. The ideal short-on failure behaviour of modules with sandwich structure after current stress over a longer period is investigated and verified by cross-section analysis. Details on the inverter reconfiguration and post-fault operation strategy are explained in theory and with a prototype. The new fault-tolerant inverter is less complex than known equivalents.