A Short-Circuit Safe Operation Area Identification Criterion for SiC MOSFET Power Modules

Abstract

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Investigation of Fault-Tolerant Capabilities in an Advanced Three-Level Active T-Type Converter

“…That is because the short-circuit current in SiC MOSFETs rises faster than that in the Si devices. Short-circuit behavior of the SiC MOSFETs are investigated in [14]- [15] [16]. In [14], the authors explained the design procedure of a SiC MOSFET short-circuit protection that can act under 600 ns.…”

Failure Analysis of a Degraded 1.2 kV SiC MOSFET after Short Circuit at High Temperature

“…A 2.4-kV/10-kA Non-Destructive Tester is applied to perform safe short circuit tests, whose main features are summarized in the following. The tester structure includes the following parts: a high-voltage power supply V DC which charges up a capacitor bank C DC , whose energy is used to perform the tests; a series protection that switches off, breaking the circuit right after the tests in order to prevent explosions of the DUT in the case of failure and thus allowing post-failure analysis [4]. A commercial moulded discrete 1.2-kV/90-A SiC planar MOSFET has been experimentally investigated.…”

“…However, this assumption needs to be further investigated, especially for applications requiring short-circuit proof devices operating at high ambient temperatures, such in the case of motor drives applications. Many efforts have been devoted to the short-circuit robustness testing of SiC MOSFETs under non-destructive operations; while some of them investigated the ageing of the device with a Repetitive Short Circuit testing approach [1]- [3], others identified degradation mechanisms with a stressful singleevent short circuit test [4]- [6].…”

“…Another failure mode typically observed after a short circuit event is a thermal runaway failure. Two indicators have been pointed out; a large turn-off tail current [4] and an uncontrolled increase of the drain current at the end of the short-circuit pulse [5]. The uneven current and temperature distribution inside the chip has been proposed as the root cause, which in turns triggers thermal instabilities leading to leakage current increase.…”

Capacitive effects in IGBTs limiting their reliability under short circuit

“…With regard to this, the IGBT short-circuit robustness is nowadays compromised by a ringing phenomenon occurring under adverse combinations of large stray inductances under certain operation conditions. Such oscillations have only been reported for IGBTs, for example, SiC MOSFETs do not show oscillatory behaviour during short circuit [2,3]. The root cause has not been well understood yet and today's IGBTs may catastrophically fail in case that the gate voltage oscillation amplitude diverges, leading to a gate-oxide breakdown [4].…”