Quasi-Flying Gate Concept Used for Short-Circuit Detection on SiC Power MOSFETs Based on a Dual-Port Gate Driver
Mathis Picot-Digoix, Frédéric Richardeau, Jean‐Marc Blaquière, Sébastien Vinnac, Stéphane Azzopardi, Thanh-Long Le
Abstract
The proposed dual-port gate driver architecture relies on a quasi-flying gate concept to protect SiC power <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s against short-circuit events. Hard switching faults (HSFs) extract charges from the gate by causing a leakage current toward the source, while faults under load (FUL) lead to charge injection into the gate through the reverse transfer capacitance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> ). Such phenomena lead to perturbations of the gate–source voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> ), which are amplified by the gate resistor, acting as an enhancer of short-circuit signatures. Thus, a small gate resistance is used to ensure high switching dynamics, while a larger one is switched <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> during pulsewidth modulation <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state operation to identify possible faults. A dual-port gate driver is then proposed to ensure fast switching with HSF and FUL monitoring. The fault detection scheme relies on comparing two thresholds to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> relative changes to the nominal gate voltage. Experimental results using TO-247 package 1.2-kV/36-A SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s exhibit promising inverter leg short-circuit detection and protection against faults in less than 300 ns.