An Intelligent Electronic Fuse for Selective Isolation of Faulty Switching Cells in Power Electronic Converter Legs to Guarantee Continuous Operation

This article proposes a novel device designated as an intelligent electronic fuse (iFuse) intended to be connected in series with any current-bidirectional voltage-unidirectional active switch present in a power converter. The iFuse duty is to selectively isolate its series-associated switch from the rest of the converter circuit immediately after detecting that this switch has failed in short circuit. Nonetheless, it maintains the reverse (free-wheeling) current path originally offered by the failed switch. The failure detection is typically performed when the failed switch causes a shoot-through event. Therefore, the iFuse is able to block large currents. The iFuse allows increasing the power-converter fault tolerance and reliability with regard to switch short-circuit failures (SCFs), as in converters featuring switches in parallel, redundant legs, and multilevel neutral-point-clamped topologies. The reliability model analysis of a two-level converter leg with two parallel switches per position reveals that its reliability can be increased up to four times when an iFuse is implemented in series with each switch. The iFuse device feasibility and good performance are verified through experimental tests, proving that it can detect and isolate the associated-switch failure in 6
$\mu \text{s}$
, while stopping short-circuit currents of up to 1 kA without incurring in harmful di / dt values.